liu.seSearch for publications in DiVA
Change search
Refine search result
1234 1 - 50 of 160
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • oxford
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the 'Create feeds' function.
  • 1.
    Ahlinder, Jon
    et al.
    Totalförsvarets Forskningsinstitut, FOI, Stockholm, Sweden.
    Nordgaard, Anders
    Linköping University, Department of Computer and Information Science, The Division of Statistics and Machine Learning. Linköping University, Faculty of Arts and Sciences. Swedish National Forensic Centre (NFC), Linköping, Sweden.
    Wiklund Lindström, Susanne
    Totalförsvarets Forskningsinstitut, FOI, Stockholm, Sweden.
    Chemometrics comes to court: evidence evaluation of chem–bio threat agent attacks2015In: Journal of Chemometrics, ISSN 0886-9383, E-ISSN 1099-128X, Vol. 29, no 5, 267-276 p.Article in journal (Refereed)
    Abstract [en]

    Forensic statistics is a well-established scientific field whose purpose is to statistically analyze evidence in order to support legal decisions. It traditionally relies on methods that assume small numbers of independent variables and multiple samples. Unfortunately, such methods are less applicable when dealing with highly correlated multivariate data sets such as those generated by emerging high throughput analytical technologies. Chemometrics is a field that has a wealth of methods for the analysis of such complex data sets, so it would be desirable to combine the two fields in order to identify best practices for forensic statistics in the future. This paper provides a brief introduction to forensic statistics and describes how chemometrics could be integrated with its established methods to improve the evaluation of evidence in court.

    The paper describes how statistics and chemometrics can be integrated, by analyzing a previous know forensic data set composed of bacterial communities from fingerprints. The presented strategy can be applied in cases where chemical and biological threat agents have been illegally disposed.

  • 2.
    Ali Soomro, Razium
    et al.
    University of Sindh, Pakistan.
    Hallam, Keith Richard
    University of Bristol, UK.
    Hussain Ibupoto, Zafar
    University of Sindh, Pakistan.
    Tahira, Aneela
    University of Sindh, Pakistan.
    Tufail Hussain Sherazi, Syed
    University of Sindh, Pakistan.
    Juddin, Siraj
    University of Sindh, Pakistan.
    Jawaid, Sana
    University of Sindh, Pakistan.
    Willander, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Glutaric Acid Assisted Fabrication of CuO Nanostructures and their Application in Development of Highly Sensitive Electrochemical Sensor System for Carbamates2016In: Electroanalysis, ISSN 1040-0397, E-ISSN 1521-4109, Vol. 28, no 7, 1634-1640 p.Article in journal (Refereed)
    Abstract [en]

    This work describes the fabrication of unique arrow head shaped CuO nanostructures using simple hydrothermal treatment method. The highly attractive features were obtained by the application of glutaric acid utilised simultaneous as template and functionalising agent. The functionalised nanostructures were known to possess excellent potential towards the electro-catalytic oxidation of carbofuran pesticide. The generated intense electrochemical signal with lower potential value enabled sensitive and selective determination of carbofuran up to 1 x 10(-3) mu M with wide sensing window in range of 0.01 to 0.16 mu M. The feasibility of the developed sensor system for the practical application was also studied by testing its potential in real sample extracts of various vegetables. The excellent recoveries demonstrated the analytical robustness of the developed sensor system. The sensor system utilises a new and simple approach towards sensitive determination of toxic pesticides reflecting its wide spectrum application in various fields.

  • 3.
    Ali Soomro, Razium
    et al.
    University of Bristol, England; University of Sindh, Pakistan.
    Hussain Ibupoto, Zafar
    Dr MA Kazi Institute Chemistry University of Sindh, Pakistan.
    Tufail Hussain Sirajuddin; Sherazi, Syed
    University of Sindh, Pakistan.
    Ishaq Abro, Muhammad
    Mehran University of Engn and Technology, Pakistan.
    Willander, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Practice of diclofenac sodium for the hydrothermal growth of NiO nanostructures and their application for enzyme free glucose biosensor2016In: Microsystem Technologies: Micro- and Nanosystems Information Storage and Processing Systems, ISSN 0946-7076, E-ISSN 1432-1858, Vol. 22, no 10, 2549-2557 p.Article in journal (Refereed)
    Abstract [en]

    In this study diclofenac sodium (DFS), an analgesic drug has been employed as an effective template for the synthesis of NiO nanostructures. The NiO nanostructures were synthesised using low temperature hydrothermal growth method, both in the presence and absence of the DFS drug. The synthesised nanostructures were studied for their structural, compositional and electrochemical properties using scanning electron microscopy, X-ray diffraction and cyclic voltammetry. The synthesised nanostructures were then utilised for the modification of glassy carbon electrode which were then utilised for the electro-catalytic enzyme free glucose sensing in alkaline media. The competitive experiments suggested that although, both nanostructures possess excellent capability of glucose sensing, the NiO nanoflakes modified electrode was found to be twice as much as sensitive (2584 A mu A mM(-1) cm(-2)) as nanoflowers based electrode (1154 A mu A mM(-1) cm(-2)). The NiO nanoflakes based sensor further demonstrated excellent anti-interference potential in the presence of common interferents like uric acid, ascorbic acid and dopamine. In addition, the successful application NiO nanoflakes based sensor to determine real blood glucose concentration further suggest its feasibility for real sample analysis.

  • 4.
    Ali Soomro, Razium
    et al.
    University of Bristol, England; University of Sindh, Pakistan.
    Nafady, Ayman
    King Saud University, Saudi Arabia; Sohag University, Egypt.
    Hallam, Keith Richard
    University of Bristol, England.
    Jawaid, Sana
    University of Sindh, Pakistan.
    Al Enizi, Abdullah
    King Saud University, Saudi Arabia.
    Tufail Hussain Sherazi, Syed
    University of Sindh, Pakistan.
    Sirajuddin,
    Univ Sindh, Natl Ctr Excellence Analyt Chem, Jamshoro 76080, Pakistan.
    Ibupoto, Zafar Hussain
    Univ Sindh, Dr MA Kazi Inst Chem, Jamshoro 76080, Pakistan.
    Willander, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Highly sensitive determination of atropine using cobalt oxide nanostructures: Influence of functional groups on the signal sensitivity2016In: Analytica Chimica Acta, ISSN 0003-2670, E-ISSN 1873-4324, Vol. 948, 30-39 p.Article in journal (Refereed)
    Abstract [en]

    This study describes sensitive determination of atropine using glassy carbon electrodes (GCE) modified with Co3O4 nanostructures. The as-synthesised nanostructures were grown using cysteine (CYS), glutathione (GSH) and histidine (HYS) as effective templates under hydrothermal action. The obtained morphologies revealed interesting structural features, including both cavity-based and flower-shaped structures. The as-synthesised morphologies were noted to actively participate in electro-catalysis of atropine (AT) drug where GSH-assisted structures exhibited the best signal response in terms of current density and over-potential value. The study also discusses the influence of functional groups on the signal sensitivity of atropine electro-oxidation. The functionalisation was carried with the amino acids originally used as effective templates for the growth of Co3O4 nanostructures. The highest increment was obtained when GSH was used as the surface functionalising agent. The GSH-functionalised Co3O4-modified electrode was utilised for the electro-chemical sensing of AT in a concentration range of 0.01 -0.46 mu M. The developed sensor exhibited excellent working linearity (R-2 = 0.999) and signal sensitivity up to 0.001 mu M of AT. The noted high sensitivity of the sensor is associated with the synergy of superb surface architectures and favourable interaction facilitating the electron transfer kinetics for the electro-catalytic oxidation of AT. Significantly, the developed sensor demonstrated excellent working capability when used for AT detection in human urine samples with strong anti-interference potential against common co-existing species, such as glucose, fructose, cysteine, uric acid, dopamine and ascorbic acid. (C) 2016 Elsevier B.V. All rights reserved.

  • 5.
    Alm, Johanna
    Linköping University, Department of Physics, Chemistry and Biology.
    Method development for identification of N-linked glycans by high performance anion exchange chromatography with pulsed amperometric detection and time of flight mass spectrometry2011Independent thesis Basic level (university diploma), 10,5 credits / 16 HE creditsStudent thesis
    Abstract [en]

    In the biopharmaceutical industry, identification of glycans in a glycoprotein is a regulatory requirement and is a part of the characterization of the protein. Glycans are constructed of several monosaccharides linked together. N-linked glycans, which have been studied in this project, are attached to the nitrogen atom in asparagine.

    A method for separating N-linked glycans by high performance anion exchange chromatography had already been developed at the department. To develop a method for identification of the N-glycans by mass spectrometry, a desalting method on porous graphitic carbon (PGC) columns was used and optimized resulting in the eluents A (0,05% TFA in ACN:water 5:95 v/v) and B (0,05% TFA in ACN:water 50:50 v/v). Also the sample introduction on the mass spectrometer was optimized and resulted in a sensitive on-line liquid chromatography mass spectrometry (LC-MS) approach which gave mass spectrometric peaks with high signal to noise ratios and with high mass accuracy.

    The developed procedure was then successfully used on glycans cleaved from a glycoprotein separated by high performance anion exchange chromatography with pulsed amperometric detector.

     

  • 6.
    Anwar Zainuddin, Ahmad
    et al.
    IIUM, Malaysia.
    Nurashikin Nordin, Anis
    IIUM, Malaysia.
    Ab Rahim, Rosminazuin
    IIUM, Malaysia.
    Mak, Wing Cheung
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, Faculty of Science & Engineering.
    Modeling of a Novel Biosensor with Integrated Mass and Electrochemical Sensing Capabilities2016In: 2016 IEEE EMBS CONFERENCE ON BIOMEDICAL ENGINEERING AND SCIENCES (IECBES), IEEE , 2016, 420-425 p.Conference paper (Refereed)
    Abstract [en]

    Rapid development in technology and society has generated diverse developments in many fields including biosensors in healthcare application. Here, the design of integrated biosensor comprises mass sensing (Quartz Crystal Microbalance) and electrochemistry sensing (Electrochemical Impedance Spectroscopy, EIS and Cyclic Voltammetry, CV) will be presented. The integrated sensor system is developed based on the innovative use of the top electrode of a quartz crystal microbalance (QCM) resonator as a working electrode for the electrochemistry technique. Integration of QCM with the electrochemistry technique is realized by fabricating a semicircular counter electrode near the upper electrode on the same side of the quartz crystal. CV and EIS measurement was conducted using finite element modeling, COMSOL (TM) 5.2 with the probe marker of 1 mmol L-1 of [Fe(CN)(6)](3-/4-). CV test was done to study the effect between increasing scan rate and peak current (anodic and cathodic) in observing the reversible electrochemical process. This observation is crucial in ensuring the electrochemical processes follow the Randles-Sevcik equation in characterizing the platform changes behavior. Later, EIS test was performed in order to measure the radius of the semicircle which reflects the charge transfer resistance (R-CT) of the redox marker. To show the effectiveness of this sensor, gold immobilization surface was electrochemically simulated and reported. Thus, an ultra-sensitive biosensor that capable to produce multi-analysis in the detection of biological targets in terms of electrochemical change of electrode interfaces, which is the crucial step towards the engineering of advanced bioelectronics.

  • 7.
    Arund, Jurgen
    et al.
    Tallinn University of Technology, Estonia.
    Luman, Merike
    North Estonia Medical Centre, Estonia.
    Uhlin, Fredrik
    Region Östergötland, Heart and Medicine Center, Department of Nephrology. Linköping University, Faculty of Medicine and Health Sciences. Linköping University, Department of Medical and Health Sciences, Division of Drug Research. Tallinn University of Technology, Estonia.
    Tanner, Risto
    Tallinn University of Technology, Estonia.
    Fridolin, Ivo
    Tallinn University of Technology, Estonia.
    Is Fluorescence Valid to Monitor Removal of Protein Bound Uremic Solutes in Dialysis?2016In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 11, no 5, e0156541Article in journal (Refereed)
    Abstract [en]

    The aim of this study was to evaluate the contribution and removal dynamics of the main fluorophores during dialysis by analyzing the spent dialysate samples to prove the hypothesis whether the fluorescence of spent dialysate can be utilized for monitoring removal of any of the protein bound uremic solute. A high performance liquid chromatography system was used to separate and quantify fluorophoric solutes in the spent dialysate sampled at the start and the end of 99 dialysis sessions, including 57 hemodialysis and 42 hemodiafiltration treatments. Fluorescence was acquired at excitation 280 nm and emission 360 nm. The main fluorophores found in samples were identified as indole derivatives: tryptophan, indoxyl glucuronide, indoxyl sulfate, 5-hydroxy-indoleacetic acid, indoleacetyl glutamine, and indoleacetic acid. The highest contribution (35 +/- 11%) was found to arise from indoxyl sulfate. Strong correlation between contribution values at the start and end of dialysis (R-2 = 0.90) indicated to the stable contribution during the course of the dialysis. The reduction ratio of indoxyl sulfate was very close to the decrease of the total fluorescence signal of the spent dialysate (49 +/- 14% vs 51 +/- 13% respectively, P = 0.30, N = 99) and there was strong correlation between these reduction ratio values (R-2 = 0.86). On-line fluorescence measurements were carried out to illustrate the technological possibility for real-time dialysis fluorescence monitoring reflecting the removal of the main fluorophores from blood into spent dialysate. In summary, since a predominant part of the fluorescence signal at excitation 280 nm and emission 360 nm in the spent dialysate originates from protein bound derivatives of indoles, metabolites of tryptophan and indole, the fluorescence signal at this wavelength region has high potential to be utilized for monitoring the removal of slowly dialyzed uremic toxin indoxyl sulfate.

  • 8.
    Azzouzi, Sawsen
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, Faculty of Science & Engineering. University of Sousse, Tunisia.
    Mak, Wing Cheung
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, Faculty of Science & Engineering.
    Kor, Kamalodin
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, Faculty of Science & Engineering. Iranian National Institute Oceanog and Atmospher Science, Iran.
    Turner, Anthony
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, Faculty of Science & Engineering.
    Ben Ali, Mounir
    University of Sousse, Higher Institute of Applied Sciences and Technology of Sousse, GREENS-ISSAT, Cité Ettafala, 4003 Ibn Khaldoun Sousse, Tunisia.
    Beni, Valerio
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, Faculty of Science & Engineering. ACREO SWEDISH ICE AB, Sweden.
    An integrated dual functional recognition/amplification bio-label for the one-step impedimetric detection of Micro-RNA-212017In: Biosensors & bioelectronics, ISSN 0956-5663, E-ISSN 1873-4235, Vol. 92, 154-161 p.Article in journal (Refereed)
    Abstract [en]

    Alteration in expression of miRNAs has been correlated with different cancer types, tumour stage and response to treatments. In this context, a structurally responsive oligonucleotide-based electrochemical impedimetric biosensor has been developed for the simple and sensitive detection of miRNA-21. A highly specific biotinylated DNA/LNA molecular beacon (MB) probe was conjugated with gold nanoparticles (AuNPs) to create an integrated, dual function bio-label (biotin-MB-AuNPs) for both biorecognition and signal generation. In the presence of target miRNA-21, hybridisation takes place resulting in the "activation" of the biotin-MB; this event makes the biotin group, which was previously "protected" by the steric hindrance of the MB stem-loop structure, accessible. The activated biotin-MB-AuNPs/miRNA complexes become available for capture, via supramolecular interaction, onto a nentravidin-modified electrode for electrochemical transduction. The binding event results in a decrease of the charge transfer resistance at the working electrode/electrolyte interface. The biosensor responded linearly in the range 1-1000 pM of miRNA-21, with a limit of detection of 0.3 pM, good reproducibility (Relative Standard deviation (RSD) =3.3%) and high selectivity over other miRNAs (i.e. miRNA221 and miRNA-205) sequences. Detection of miRNA-21 in spiked serum samples at clinically relevant levels (low pM range) was also demonstrated, thus illustrating the potential of the biosensor for point-of-care clinical applications. The proposed biosensor design, based on the combination of a neutravidin transducing surface and the dual-function biotin-MB-AuNPs bio-label, provides a simple and robust approach for detection of short-length nucleic acid targets, such as miRNAs.

    The full text will be freely available from 2019-02-10 10:23
  • 9.
    Azzouzi, Sawsen
    et al.
    University of Sousse, Tunisia.
    Patra, Hirak Kumar
    Linköping University, Department of Clinical and Experimental Medicine, Division of Cell Biology. Linköping University, Faculty of Medicine and Health Sciences.
    Ben Ali, Mounir
    University of Sousse, Tunisia.
    Nooredeen Abbas, Mohammed
    National Research Centre, Egypt.
    Dridi, Cherif
    Centre Research Microelect and Nanotechnol CRMN Sousse, Tunisia.
    Errachid, Abdelhamid
    University of Lyon 1, France.
    Turner, Anthony
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, Faculty of Science & Engineering.
    Citrate-selective electrochemical mu-sensor for early stage detection of prostate cancer2016In: Sensors and actuators. B, Chemical, ISSN 0925-4005, E-ISSN 1873-3077, Vol. 228, 335-346 p.Article in journal (Refereed)
    Abstract [en]

    The extremely specialised anatomical function of citrate inside the prostate, make it one of the preferred biomarkers for early stage detection of prostate cancer. However, current detection methods are seriously limited due to the very low citrate concentrations that need to be measured in order to follow disease progression. In the present work, we report a novel citrate-selective-sensor based on iron (III) phthalocyanine chloride-C-monoamido-Poly-n-Butyl Acrylate (Fe(III)MAPcC1 P n BA) modified gold -electrodes for the electrochemical determination and estimation of the pathophysiological range of citrate. The newly synthesised ionophore has been structurally characterised using Fourier transform infrared (FTIR) and UV-vis spectroscopy. Contact angle measurements and atomic force microscopy (AFM) have been used to investigate the adhesion and morphological properties of the membrane. The developed citrate-selective-electrodes had a Nernstian sensitivity of-19.34 +/- 0.83 mV/decade with a detection limit of about 9 x 10-6M and a linear range from 4 x 10(-5)M to 10(-1) M, which covered the pathologically important clinical range. Electrochemical impedance spectroscopy (EIS) showed very high sensitivity with a lower Limit of detection 1.7 x 10(-9) M and linear detection range (10(-8)-10(-1) M), which is very important not only for the early-stage diagnosis and screening procedures, but also in mapping the stage of the cancer too. (C) 2016 Elsevier B.V. All rights reserved.

  • 10.
    Baloach, Qurrat-ul-ain
    et al.
    University of Sindh, Pakistan.
    Nafady, Ayman
    King Saud University, Saudi Arabia; Sohag University, Egypt.
    Tahira, Aneela
    University of Sindh, Pakistan.
    Tufail Hussain Sirajuddin; Sherazi, Syed
    University of Sindh, Pakistan.
    Shaikh, Tayyaba
    University of Sindh, Pakistan.
    Arain, Munazza
    University of Sindh, Pakistan.
    Willander, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Hussain Ibupoto, Zafar
    University of Sindh, Pakistan.
    An amperometric sensitive dopamine biosensor based on novel copper oxide nanostructures2017In: Microsystem Technologies: Micro- and Nanosystems Information Storage and Processing Systems, ISSN 0946-7076, E-ISSN 1432-1858, Vol. 23, no 5, 1229-1235 p.Article in journal (Refereed)
    Abstract [en]

    It is highly important to explore the influence of counter anions on the morphology in order to have a desired nanostructure with unique properties. Therefore, in this research work the influence of counter anions on the morphology of copper oxide (CuO) nanostructures is presented using copper chloride and copper acetate salts. A significant role of counter anions on the morphology of CuO nanostructures is observed. The hydrothermal method is used to carry out the synthesis of CuO nanomaterial. The prepared CuO nanostructures are characterized by scanning electron microscopy and X-ray diffraction techniques. The prepared CuO nanomaterial exhibits porous nature with thin nanowires and sponge like morphologies. The dopamine sensing application was carried for exploring the electrocatalytic properties of CuO nanostructures. The presented dopamine biosensor exhibited wide linear range for detection of dopamine from 5 to 40 A mu M with sensitivity of 12.8 A mu A mM(-1) cm(-2). The limit of detection and limit of quantification were estimated in order 0.11 and 0.38 A mu M respectively. The developed dopamine biosensor is highly sensitive, selective, stable and reproducible. The common interfering species such as glucose, ascorbic acid and uric acid showed negligible change in the current when same concentration of dopamine and these interfering species was used. The fabricated biosensor could be used for the determination of dopamine from real blood samples.

  • 11.
    Baloach, Qurrat-ul-Ain
    et al.
    University of Sindh, Pakistan.
    Tahira, Aneela
    University of Sindh, Pakistan.
    Begum Mallah, Arfana
    University of Sindh, Pakistan.
    Ishaq Abro, Muhammad
    Mehran University of Engn and Technology, Pakistan.
    Uddin, Siraj
    University of Sindh, Pakistan.
    Willander, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Hussain Ibupoto, Zafar
    University of Sindh, Pakistan.
    A Robust, Enzyme-Free Glucose Sensor Based on Lysine-Assisted CuO Nanostructures2016In: Sensors, ISSN 1424-8220, E-ISSN 1424-8220, Vol. 16, no 11, 1878Article in journal (Refereed)
    Abstract [en]

    The production of a nanomaterial with enhanced and desirable electrocatalytic properties is of prime importance, and the commercialization of devices containing these materials is a challenging task. In this study, unique cupric oxide (CuO) nanostructures were synthesized using lysine as a soft template for the evolution of morphology via a rapid and boiled hydrothermal method. The morphology and structure of the synthesized CuO nanomaterial were characterized using scanning electron microscopy (SEM) and X-ray diffraction (XRD), respectively. The prepared CuO nanostructures showed high potential for use in the electrocatalytic oxidation of glucose in an alkaline medium. The proposed enzyme-free glucose sensor demonstrated a robust response to glucose with a wide linear range and high sensitivity, selectivity, stability, and reproducibility. To explore its practical feasibility, the glucose content of serum samples was successfully determined using the enzyme-free sensor. An analytical recovery method was used to measure the actual glucose from the serum samples, and the results were satisfactory. Moreover, the presented glucose sensor has high chemical stability and can be reused for repetitive measurements. This study introduces an enzyme-free glucose sensor as an alternative tool for clinical glucose quantification.

  • 12.
    Bengtsson, Katarina
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Electrokinetic devices from polymeric materials2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    There are multiple applications for polymers: our bodies are built of them, plastic bags and boxes used for storage are composed of them, as are the shells for electronics, TVs, computers, clothes etc. Many polymers are cheap, and easy to manufacture and process which make them suitable for disposable systems. The choice of polymer to construct an object will therefore highly influence the properties of the object itself. The focus of this thesis is the application of commonly used polymers to solve some challenges regarding integration of electrodes in electrokinetic devices and 3D printing.

    The first part of this thesis regards electrokinetic systems and the electrodes’ impact on the system. Electrokinetic systems require Faradaic (electrochemical) reactions at the electrodes to maintain an electric field in an electrolyte. The electrochemical reactions at the electrodes allow electron-to-ion transduction at the electrode-electrolyte interface, necessary to drive a current at the applied potential through the system, which thereby either cause flow (electroosmosis) or separation (electrophoresis). These electrochemical reactions at the electrodes, such as water electrolysis, are usually problematic in analytical systems and systems applied in biology. One solution to reduce the impact of water electrolysis is by replacing metal electrodes with electrochemically active polymers, e.g. poly(3,4-ethylenedioxythiophene) (PEDOT). Paper 1 demonstrates that PEDOT electrodes can replace platinum electrodes in a gel electrophoretic setup. Paper 2 reports an all-plastic, planar, flexible electroosmotic pump which continuously transports water from one side to the other using potentials as low as 0.3 V. This electroosmotic pump was further developed in paper 3, where it was made into a compact and modular setup, compatible with commercial microfluidic devices. We demonstrated that the pump could maintain an alternating flow for at least 96 h, with a sufficient flow of cell medium to keep cells alive for the same period of time.

    The second part of the thesis describes the use of 3D printers for manufacturing prototypes and the material requirements for 3D printing. Protruding and over-hanging structures are more challenging to print using a 3D printer and usually require supporting material during the printing process. In paper 4, we showed that polyethylene glycol (PEG), in combination with a carbonate-based plasticizer, functions well as a 3D printable sacrificial template material. PEG2000 with between 20 and 30 wt% dimethyl carbonate or propylene carbonate have good shear-thinning rheology, mechanical and chemical stability, and water solubility, which are advantageous for a supporting material used in 3D printing.

    The advances presented in this thesis have solved some of the challenges regarding electrokinetic systems and prototype manufacturing. Hopefully this will contribute to the development of robust, disposable, low-cost, and autonomous electrokinetic devices.

    List of papers
    1. Conducting Polymer Electrodes for Gel Electrophoresis
    Open this publication in new window or tab >>Conducting Polymer Electrodes for Gel Electrophoresis
    2014 (English)In: PLoS ONE, ISSN 1932-6203, Vol. 9, no 2, 0089416- p.Article in journal (Refereed) Published
    Abstract [en]

    In nearly all cases, electrophoresis in gels is driven via the electrolysis of water at the electrodes, where the process consumes water and produces electrochemical by-products. We have previously demonstrated that p-conjugated polymers such as poly(3,4-ethylenedioxythiophene) (PEDOT) can be placed between traditional metal electrodes and an electrolyte to mitigate electrolysis in liquid (capillary electroosmosis/electrophoresis) systems. In this report, we extend our previous result to gel electrophoresis, and show that electrodes containing PEDOT can be used with a commercial polyacrylamide gel electrophoresis system with minimal impact to the resulting gel image or the ionic transport measured during a separation.

    Place, publisher, year, edition, pages
    Public Library of Science, 2014
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-105901 (URN)10.1371/journal.pone.0089416 (DOI)000331711900141 ()
    Available from: 2014-04-14 Created: 2014-04-12 Last updated: 2017-08-18Bibliographically approved
  • 13.
    Beni, Valerio
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics.
    Biosensors for Food and the Environment: Is it all in the DNA?2013Conference paper (Other academic)
    Abstract [en]

    Biosensor technology not only holds great promise for the healthcare market but it is also expected to have significant impacts in other areas such as environmental and food analysis. Between the different biosensor formats nucleic acid-based biosensors are gaining increasingly importance allowing the specific identification of DNA/RNA fragments and, more recently, the detection of biological or chemical species. Direct identification of DNA/RNA fragments, via hybridisation assays (genosensors), has been shown to be a very powerful tool for the detection of pathogens in environment and food, in food contamination analysis and food allergens monitoring. Recently the discovery of aptamers, synthetic receptors based on short functional DNA/RNA chains, has opened new opportunities for oligonucleotide based biosensors and more specifically in the detection of biological and/or chemical species, such as proteins and pollutants. In this paper an overview of the most recent advances in the development and applications of nucleic acid-based biosensors for environmental and food safety/quality application will be presented with special emphasis on electrochemical and optical hybridisation genosensors and aptasensors.

  • 14.
    Beni, Valerio
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, The Institute of Technology.
    Development of an electrochemical genosensors for celiac disease predisposition analysis2013In: "Biomimetic structures and DNA technology in biosensing" / [ed] Tibor Hianik, 2013, 21- p.Conference paper (Other academic)
    Abstract [en]

    Low density DNA arrays are of growing interest in the field of fast clinical/environmental analysis; for example in clinical analysis these can find application in areas as early diagnosis of genetic diseases or as support in the diagnosis of genetically associated diseases. 

    Coeliac disease, a small intestinal inflammation triggered by the intake of gluten, has been shown to affect only genetically predisposed individuals. Relation between Coeliac disease and two Human Leukocyte Antigens (HLA) genes, DQ2 and DQ8, has been reported, with almost 100% of the affected patients carrying at least one of them.

    In this seminar the development of a low density electrochemical genosensor array for medium resolution typing of Coeliac disease associated HLA genes, is presented.                                        

    The proposed array was based on an enzymatic sandwich assay format performed at a photolitographically fabricated electrode array.                                                                            

    The optimisation of different aspects as surface chemistry, assay conditions, probe's design and single stranded DNA generation, together with real sample analysis will be present.

     

  • 15.
    Beni, Valerio
    et al.
    Tyndall National Institute, University College Cork, Ireland.
    Arrigan, Damien
    Tyndall National Institute, University College Cork, Ireland.
    Microelectrode arrays and microfabricated devices in electrochemical stripping analysis2008In: Current Analytical Chemistry, ISSN 1573-4110, Vol. 4, no 3, 229-241 p.Article in journal (Refereed)
    Abstract [en]

    In this article a comprehensive overview of the developments in the field of electrochemical stripping analysis with microelectrode arrays and microfabricated devices is presented. Due to the vastness of the topic, this mini-review deals only with the use of regular microelectrode arrays. After the description of the main fabrication methodologies employed, a large part of the review is dedicated to applications, categorised by the electrode material. Microelectrode arrays have found application in several areas of electroanalytical science including clinical and environmental analysis. They have been used for the detection of heavy metals in waters, soil extracts and blood, proving to be reliable analytical devices and bringing the advantages of low-cost, simplicity of use and easy adaptability to field measurement. In many applications, limits of detection are sub-parts per billion. Finally a short section of the review discusses miniaturised potentiostats.

  • 16.
    Beni, Valerio
    et al.
    Tyndall National Institute, University College Cork, Ireland.
    Collins, Gilian
    Tyndall National Institute, University College Cork, Ireland.
    Arrigan, Damien
    Tyndall National Institute, University College Cork, Ireland.
    Investigation into the voltammetric behaviour and detection of selenium(IV) at metal electrodes in diverse electrolyte media2011In: Analytica Chimica Acta, ISSN 0003-2670, E-ISSN 1873-4324, Vol. 699, no 2, 127-133 p.Article in journal (Refereed)
    Abstract [en]

    The voltammetric behaviour of selenium(IV) was studied at platinum and gold electrodes in sulphuricacid, perchloric acid and potassium chloride media as a basis for its voltammetric detection. The bestvoltammetric behaviour was recorded at gold electrodes with perchloric acid as the supporting electrolyte.The concomitant presence of metals, such as copper or lead, and of model biomolecules, suchas bovine serum albumin, in the solution resulted in a deterioration of the electrochemical response forselenium(IV). Quantitative detection of selenium(IV) by square wave anodic stripping voltammetry atboth a millimetre-sized gold disc electrode and a microband electrode array revealed linear responsesto selenium concentration in the ranges 5–15 M and 0.1–10 M, respectively, with 60 s preconcentration.The sensitivities were 6.4 A M−1 cm−2 and 100 A M−1 cm−2 at the disc and the microband array,respectively. The detection limit at the microband electrode array was 25 nM, illustrating the potentialityof such microelectrodes for the development of mercury-free analytical methods for the trace detectionof selenium(IV).

  • 17.
    Beni, Valerio
    et al.
    Universitat Rovira i Virgili, Tarragona, Spain.
    Gelaw, Tilahun
    Universitat Rovira i Virgili, Tarragona, Spain.
    O´Sullivan, Ciara K.
    Universitat Rovira i Virgili, Tarragona, Spain.
    Study of the combination of the deposition/stripping of sacrificial metal nano-structures and alkanethiol as a route for genosensor surface preparation2011In: Electrochemistry communications, ISSN 1388-2481, E-ISSN 1873-1902, Vol. 13, no 4, 325-327 p.Article in journal (Refereed)
    Abstract [en]

    In the reported work the combination of electrodeposition/stripping of copper sacrificial metallic nanostructuresand alkanethiol self-assembling was investigated for the preparation of a randomly nano-patternedorganised monolayer on a gold surface. Electrochemical characterisation of the process demonstrated thepotential of the proposed approach for the random nano-patterning of a chemisorbed monolayer onconductive surfaces with minimal impact on the bulk monolayer. Finally the obtained nano-structuredsurfaces were exploited as a platform for the fabrication of an amperometric genosensor for the detection ofthe DF508 Cystic Fibrosis associated mutation.

  • 18.
    Beni, Valerio
    et al.
    NMRC, University College, Cork, Ireland.
    Ghita, Mihaela
    PSiMedica, Malvern Hills Science Park, UK.
    Arrigan, Damien
    NMRC, University College, Cork, Ireland.
    Cyclic and pulse voltammetric study of dopamine at the interfacebetween two immiscible electrolyte solutions2005In: Biosensors & bioelectronics, ISSN 0956-5663, E-ISSN 1873-4235, Vol. 20, no 10, 2097-2103 p.Article in journal (Refereed)
    Abstract [en]

    The detection of dopamine by differential pulse voltammetry (DPV) and square wave voltammetry (SWV) at the interface between twoimmiscible electrolyte solutions (ITIES) has been studied. Voltammetry at the liquid/liquid (water/1,2-dichloroethane) interface provides asimple method for overcoming the major problem associated with dopamine detection by voltammetry at solid electrodes: the co-existenceof ascorbate at higher concentrations. Selectivity for dopamine was achieved by the use of dibenzo-18-crown-6 as an ionophore for thefacilitated transfer voltammetry of protonated dopamine across the ITIES. Under these conditions, ascorbate is not transferred and hence doesnot interfere in the ion transfer current for dopamine. By use of DPV and SWV, the lowest concentration detectable can be lowered from ca.0.1mM (obtained with cyclic voltammetry) to 2 M. Evaluation of the effect of some other physiologically important species (acetylcholine,sodium, potassium and ammonium ions) on the dopamine transfer voltammetry has been studied, indicating the need for improved ionophoredesigns in order to achieve practically useful selectivity.

  • 19.
    Beni, Valerio
    et al.
    Universitat Rovira i Virgili, Tarragona, Spain.
    Hayes, Karen
    Universitat Rovira i Virgili, Tarragona, Spain.
    Mairal Lerga, Teresa
    Universitat Rovira i Virgili, Tarragona, Spain.
    O´Sullivan, Ciara K.
    Universitat Rovira i Virgili, Tarragona, Spain.
    Development of a gold nano-particle-based fluorescent molecular beacon fordetection of cystic fibrosis associated mutation2010In: Biosensors & bioelectronics, ISSN 0956-5663, E-ISSN 1873-4235, Vol. 26, no 2, 307-313 p.Article in journal (Refereed)
    Abstract [en]

    Cystic fibrosis is one of the most common genetically inherited diseases in Northern Europe, consistingof an inherited defect of chloride transport in the epithelium. Of the several mutations related to CF, theF508 mutation occurs in ca. 70% of the cases. In this work the use of a gold nano-particle supportedfluorescence molecular beacon was investigated as an optical sensing platform for the detection of theF508 cystic fibrosis associated mutation. Different parameters such as molecular beacon design, Aunano-particle size, molecular beacon–nano-particle conjugation protocol, molecular beacon loading aswell as experimental conditions were evaluated. A 31-base long molecular beacon, containing a 15-baserecognition sequence specific for the mutant target, was linked via a thiol modified poly thymine linker(10 bases long) to a 13 nm gold nano-particle and was exposed to mutant and wild type targets, and aclear differentiation was achieved at target concentrations as low as 1 nM.

  • 20.
    Beni, Valerio
    et al.
    NMRC, University College, Cork, Ireland.
    Newton, Hazel
    NMRC, University College, Cork, Ireland.
    Arrigan, Damien
    NMRC, University College, Cork, Ireland.
    Hill, Martin
    NMRC, University College, Cork, Ireland.
    Lane, William
    NMRC, University College, Cork, Ireland.
    Mathewson, Alan
    NMRC, University College, Cork, Ireland.
    Voltammetric behaviour at gold electrodes immersed in the BCR sequential extraction scheme media: Application of underpotential deposition–stripping voltammetry to determination of copper in soil extracts2004In: Analytica Chimica Acta, ISSN 0003-2670, E-ISSN 1873-4324, Vol. 502, no 2, 195-206 p.Article in journal (Refereed)
    Abstract [en]

    The development of mercury-free electroanalytical systems for in-field analysis of pollutants requires a foundation on the electrochemicalbehaviour of the chosen electrode material in the target sample matrices. In this work, the behaviour of gold working electrodes in the mediaemployed in the BCR sequential extraction protocol, for the fractionation of metals in solid environmental matrices, is reported. All three ofthe BCR sequential extraction media are redox active, on the basis of acidity and oxygen content as well as the inherent reducing or oxidisingnature of some of the reagents employed: 0.11M acetic acid, 0.1M hydroxylammonium chloride (adjusted to pH 2) and 1M ammoniumacetate (adjusted to pH 2) with added trace hydrogen peroxide. The available potential ranges together with the demonstrated detection oftarget metals in these media are presented. Stripping voltammetry of copper or lead in the BCR extract media solutions reveal a multi-peakbehaviour due to the stripping of both bulk metal and underpotential metal deposits. A procedure based on underpotential deposition–strippingvoltammetry (UPD-SV) was evaluated for application to determination of copper in 0.11M acetic acid soil extracts. A preliminary screeningstep in which different deposition times are applied to the sample enables a deposition time commensurate with UPD-SV to be selected sothat no bulk deposition or stripping occurs thus simplifying the shape and features of the resulting voltammograms. Choice of the suitabledeposition time is then followed by standards addition calibration. The method was validated by the analysis of a number of BCR 0.11Macetic acid soil extracts. Good agreement was obtained been the UPD-SV method and atomic spectroscopic results.

  • 21.
    Beni, Valerio
    et al.
    Tyndall National Institute, University College, Cork, Ireland.
    Ogurtsov, Vladimir
    Tyndall National Institute, University College, Cork, Ireland.
    Bakunin, Nikolai
    Tyndall National Institute, University College, Cork, Ireland.
    Arrigan, Damien
    Tyndall National Institute, University College, Cork, Ireland.
    Hill, Martin
    Cork Institute of Technology, Bishopstown, Cork, Ireland.
    Development of a portable electroanalytical system for the stripping voltammetry of metals: Determination of copper in acetic acid soil extracts2005In: Analytica Chimica Acta, ISSN 0003-2670, E-ISSN 1873-4324, Vol. 552, no 1-2, 190-200 p.Article in journal (Refereed)
    Abstract [en]

    The development, characterisation and evaluation of a prototype portable electrochemical trace metal analyser are presented. The instrumentis a battery-powered microcontroller-based potentiostat, which implements anodic stripping voltammetry (ASV) at suitable sensor electrodes.It is capable of operating away from the laboratory, in the absence of an external power source and is usable by low-skilled personnel. Thedistinguishing feature of the instrument is its custom software, which enables sample pre-screening, data processing and sample dilution andstandard additions calculations to be carried out. The instrument has been evaluated by application of a methodology for the detection ofcopper in acetic acid soil extracts, both in the laboratory and in the field. Underpotential deposition staircase anodic stripping voltammetry(UPD-SCASV) of the copper at gold disk electrodes was used as a test method. There was good agreement between the instrument resultsand those from laboratory-based reference analytical methods for analyses carried out both in the laboratory and in the field.

  • 22.
    Beni, Valerio
    et al.
    Universitat Rovira i Virgili, Spain.
    Zewdu, Taye
    Universitat Rovira i Virgili, Spain.
    Joda, Hamdi
    Universitat Rovira i Virgili, Spain.
    Katakis, Ioanis
    Universitat Rovira i Virgili, Spain.
    O´Sullivan, Ciara K.
    Universitat Rovira i Virgili, Spain.
    Gold nanoparticle fluorescent molecular beacon for low-resolution DQ2 gene HLA typing2012In: Analytical and Bioanalytical Chemistry, ISSN 1618-2642, E-ISSN 1618-2650, Vol. 402, no 3, 1001-1009 p.Article in journal (Refereed)
    Abstract [en]

    Coeliac disease is an inflammation of the small intestine triggered by gluten ingestion. We present a fluorescent genosensor, exploiting molecular-beacon-functionalized gold nanoparticles, for the identification of human leukocyte antigen (HLA) DQ2 gene, a key genetic factor in coeliac disease. Optimization of sensor performance was achieved by tuning the composition of the oligonucleotide monolayer immobilized on the gold nanoparticle and the molecular beacon design. Co-immobilization of the molecular beacon with a spacing oligonucleotide (thiolated ten-thymine oligonucleotide) in the presence of ten-adenine oligonucleotides resulted in a significant increase of the sensor response owing to improved spacing of the molecular beacons and extension of the distance from the nanoparticle surface, which renders them more available for recognition. Further increase in the response (approximately 40%) was shown to be achievable when the recognition sequence of the molecular beacon was incorporated in the stem. Improvement of the specificity of the molecular beacons was also achieved by the incorporation within their recognition sequence of a one-base mismatch. Finally, gold nanoparticles functionalized with two molecular beacons targeting the DQA1*05* and DQB1*02* alleles allowed the low-resolution typing of the DQ2 gene at the nanomolar level.

  • 23.
    Benskin, Jonathan
    et al.
    University of Alberta, Canada.
    Ahrens, Lutz
    Institute for Coastal Research, Geesthacht, Tyskland.
    Muir, Derek
    Environment Canada, Kanada.
    Scott, Brian
    Environment Canada, Kanada.
    Spencer, Christine
    Environment Canada, Kanada.
    Rosenberg, Bruno
    Department of Fisheries and Oceans, Canada.
    Tomy, Gregg
    Department of Fisheries and Oceans, Canada.
    Kylin, Henrik
    Linköping University, The Tema Institute, Department of Water and Environmental Studies. Linköping University, Faculty of Arts and Sciences.
    Lohmann, Rainer
    University of Rhode Island, USA.
    Martin, Jonathan
    University of Alberta, Canada.
    Manufacturing Origin of Perfluorooctanoate (PFOA) in Atlantic and Canadian Arctic Seawater2012In: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 46, no 2, 677-685 p.Article in journal (Refereed)
    Abstract [en]

    The extent to which different manufacturing sources and long-range transport pathways contribute to perfluorooctanoate (PFOA) in the world’s oceans, particularly in remote locations, is widely debated. Here, the relative contribution of historic (i.e., electrochemically fluorinated) and contemporary (i.e., telomer) manufacturing sources was assessed for PFOA in various seawater samples by an established isomer profiling technique. The ratios of individual branched PFOA isomers were indistinguishable from those in authentic historic standards in 93% of the samples examined, indicating that marine processes had little influence on isomer profiles, and that isomer profiling is a valid source apportionment tool for seawater. Eastern Atlantic PFOA was largely (83−98%) of historic origin, but this decreased to only 33% close to the Eastern U.S. seaboard. Similarly, PFOA in the Norwegian Sea was near exclusively historic, but the relative contribution decreased to ∼50% near the Baltic Sea. Such observations of contemporary PFOA in coastal source regions coincided with elevated concentrations, suggesting that the continued production and use of PFOA is currently adding to the marine burden of this contaminant. In the Arctic, a spatial trend was observed whereby PFOA in seawater originating from the Atlantic was predominantly historic (up to 99%), whereas water in the Archipelago (i.e., from the Pacific) was predominantly of contemporary origin (as little as 17% historic). These data help to explain reported temporal and spatial trends from Arctic wildlife biomonitoring, and suggest that the dominant PFOA source(s) to the Pacific and Canadian Arctic Archipelago are either (a) from direct emissions of contemporary PFOA via manufacturing or use in Asia, or (b) from atmospheric transport and oxidation of contemporary PFOA-precursors.

  • 24.
    Benskin, Jonathan P.
    et al.
    University of Alberta, Canada .
    Muir, Derek C. G.
    Environm Canada, Canada .
    Scott, Brian F.
    Environm Canada, Canada .
    Spencer, Christine
    Environm Canada, Canada .
    De Silva, Amila O.
    Environm Canada, Canada .
    Kylin, Henrik
    Linköping University, The Tema Institute, Department of Water and Environmental Studies. Linköping University, Faculty of Arts and Sciences.
    Martin, Jonathan W.
    University of Alberta, Canada .
    Morris, Adam
    University of Guelph, Canada .
    Lohmann, Rainer
    University of Rhode Isl, RI 02882 USA .
    Tomy, Gregg
    Department Fisheries and Oceans Canada, Canada .
    Rosenberg, Bruno
    Department Fisheries and Oceans Canada, Canada .
    Taniyasu, Sachi
    National Institute Adv Ind Science and Technology, Japan .
    Yamashita, Nobuyoshi
    National Institute Adv Ind Science and Technology, Japan .
    Perfluoroalkyl Acids in the Atlantic and Canadian Arctic Oceans2012In: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 46, no 11, 5815-5823 p.Article in journal (Refereed)
    Abstract [en]

    We report here on the spatial distribution of C-4, C-6, and C-8 perfluoroalkyl sulfonates, C-6-C-14 perfluoroalkyl carboxylates, and perfluorooctanesulfonamide in the Atlantic and Arctic Oceans, including previously unstudied coastal waters of North and South America, and the Canadian Arctic Archipelago. Perfluorooctanoate (PFOA) and perfluorooctanesulfonate (PFOS) were typically the dominant perfluoroalkyl acids (PFAAs) in Atlantic water. In the midnorthwest Atlantic/Gulf Stream, sum PFAA concentrations (Sigma PFAAs) were low (77-190 pg/L) but increased rapidly upon crossing into U.S. coastal water (up to 5800 pg/L near Rhode Island). Sigma PFAAs in the northeast Atlantic were highest north of the Canary Islands (280-980 pg/L) and decreased with latitude. In the South Atlantic, concentrations increased near Rio de la Plata (Argentina/Uruguay; 350-540 pg/L Sigma PFAAs), possibly attributable to insecticides containing N-ethyl perfluorooctanesulfonamide, or proximity to Montevideo and Buenos Aires. In all other southern hemisphere locations, Sigma PFAAs were less than210 pg/L. PFOA/PFOS ratios were typically greater than= 1 in the northern hemisphere, similar to 1 near the equator, and less than= 1 in the southern hemisphere. In the Canadian Arctic, Sigma PFAAs ranged from 40 to 250 pg/L, with perfluoroheptanoate, PFOA, and PFOS among the PFAAs detected at the highest concentrations. PFOA/PFOS ratios (typically greater thangreater than1) decreased from Baffin Bay to the Amundsen Gulf; possibly attributable to increased atmospheric inputs. These data help validate global emissions models and contribute to understanding of long-range transport pathways and sources of PFAAs to remote regions.

  • 25.
    Berduque, Alfonso
    et al.
    Tyndall National Institute, University College, Cork, Ireland.
    Lanyon, Yvonne
    Tyndall National Institute, University College, Cork, Ireland.
    Beni, Valerio
    Tyndall National Institute, University College, Cork, Ireland.
    Herzog, Gregoire
    Tyndall National Institute, University College, Cork, Ireland.
    Watson, Yvonne
    Tyndall National Institute, University College, Cork, Ireland.
    Rodgers, Kenneth
    Tyndall National Institute, University College, Cork, Ireland.
    Stam, Frank
    Tyndall National Institute, University College, Cork, Ireland.
    Alderman, John
    Tyndall National Institute, University College, Cork, Ireland.
    Arrigan, Damien
    Tyndall National Institute, University College, Cork, Ireland.
    Voltammetric characterisation of silicon-based microelectrode arrays and their application to mercury-free stripping voltammetry of copper ions2007In: Talanta: The International Journal of Pure and Applied Analytical Chemistry, ISSN 0039-9140, E-ISSN 1873-3573, Vol. 71, no 3, 1022-1030 p.Article in journal (Refereed)
    Abstract [en]

    This paper describes the electrochemical characterisation of a range of gold and platinum microelectrode arrays (MEAs) fabricated by standardphotolithographic methods. The inter-electrode spacing, geometry, numbers and dimensions of the electrodes in the arrays were found to influencethe voltammetric behaviours obtained. Excellent correlation was found between experimental data and theoretical predictions employing publishedmodels of microelectrode behaviour. Gold MEAs were evaluated for their applicability to copper determination in a soil extract sample, whereagreement was found between the standard analytical method and a method based on underpotential deposition—anodic stripping voltammetry(UPD-ASV) at the MEAs, offering a mercury-free alternative for copper sensing.

  • 26.
    Bergman, Nina
    Linköping University, Department of Physics, Chemistry and Biology.
    Sample preparation of 8-hydroxy-2’-deoxyguanosine with solid phase extraction methodology based on molecular imprinting polymers and conventional silica based phases2011Independent thesis Basic level (degree of Bachelor), 10,5 credits / 16 HE creditsStudent thesis
    Abstract [en]

    The aim of this study was to develop methods for sample preparation for 8-OHdG in blood plasma samples with different solid phase extraction techniques using HPLC with an elec- trochemical detector. The solid phase extraction cartridges used were Chromabond® C18, Oasis® MAX, and three types of SupelMIPTM cartridges for chloramphenicol, riboflavin, and nitroimidazoles. The SupelMIPTM cartridges are based on molecularly imprinted polymers- technique. The separation of 8-OHdG in samples extracted from blood plasma was carried out with a Thermo Quest Hypersil Division ODS column (250 mm × 4 mm, 3μm I.D.) and methanol:buffer (10:90, v/v) as mobile phase. Recovery and selectivity was studied for the different solid phase extraction methods. The highest recovery was obtained using the Chromabond C18 cartridge with a recovery of 92%, and CV coefficient 9.5% (n = 4). 8-OHdG could not be extracted on MIP-cartridges for chloramphenicol or riboflavin, but was retained on MIP columns for nitroimidazoles, and the highest recovery was 49%.

  • 27.
    Berto, Marcello
    et al.
    University of Modena and Reggio Emilia, Italy.
    Casalini, Stefano
    University of Modena and Reggio Emilia, Italy; Institute Ciencia Mat Barcelona ICMAB CSIC, Spain.
    Di Lauro, Michele
    University of Modena and Reggio Emilia, Italy.
    Marasso, Simone L.
    Politecn Torino, Italy; IMEM CNR, Italy.
    Cocuzza, Matteo
    Politecn Torino, Italy; IMEM CNR, Italy.
    Perrone, Denis
    Ist Italiano Tecnol, Italy.
    Pinti, Marcello
    University of Modena and Reggio Emilia, Italy.
    Cossarizza, Andrea
    University of Modena and Reggio Emilia, Italy.
    Pirri, Candido F.
    Politecn Torino, Italy; Ist Italiano Tecnol, Italy.
    Simon, Daniel
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Berggren, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Zerbetto, Francesco
    University of Bologna, Italy.
    Bortolotti, Carlo A.
    University of Modena and Reggio Emilia, Italy.
    Biscarini, Fabio
    University of Modena and Reggio Emilia, Italy.
    Biorecognition in Organic Field Effect Transistors Biosensors: The Role of the Density of States of the Organic Semiconductor2016In: ANALYTICAL CHEMISTRY, ISSN 0003-2700, Vol. 88, no 24, 12330-12338 p.Article in journal (Refereed)
    Abstract [en]

    Biorecognition is a central event in biological processes in the living systems that is also widely exploited in technological and health applications. We demonstrate that the Electrolyte Gated Organic Field Effect Transistor (EGOFET) is an ultrasensitive and specific device that allows us to quantitatively assess the thermodynamics of biomolecular recognition between a human antibody and its antigen, namely, the inflammatory cytokine TNF alpha at the solid/liquid interface. The EGOFET biosensor exhibits a superexponential response at TNF alpha concentration below 1 nM with a minimum detection level of 100 pM. The sensitivity of the device depends on the analyte concentration, reaching a maximum in the range of clinically relevant TNF alpha concentrations when the EGOFET is operated in the subthreshold regime. At concentrations greater than 1 nM the response scales linearly with the concentration. The sensitivity and the dynamic range are both modulated by the gate voltage. These results are explained by establishing the correlation between the sensitivity and the density of states (DOS) of the organic semiconductor. Then, the superexponential response arises from the energy-dependence of the tail of the DOS of the HOMO level. From the gate voltage-dependent response, we extract the binding constant, as well as the changes of the surface charge and the effective capacitance accompanying biorecognition at the electrode surface. Finally, we demonstrate the detection of TNF alpha in human-plasma derived samples as an example for point-of-care application.

    The full text will be freely available from 2017-11-25 15:36
  • 28.
    Bohlin, Nina
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, The Institute of Technology.
    Kemiskt försvar mot havstulpanskolonisering i marina svampdjur2013Independent thesis Basic level (degree of Bachelor), 10,5 credits / 16 HE creditsStudent thesis
    Abstract [en]

    The purpose of this project is to analyze and study the absorption of the substances ivermectin, spinosad and barettin to hydrophobic and hydrophilic surfaces, and to analyze and study if the barnacle larva are effected when they try to settle on the treated surface.

    Incubation tests with barnacle larva in Petri dishes were performed as well as absorption tests on hydrophobic and hydrophilic surfaces which were tested with ellipsometry. To determine the surface thickness.

    The barnacles were placed in hydrophobic as well as hydrophilic Petri dishes that had been incubated with ivermectin, spinosad or barettin. After four to six days the larva was counted to analyze the settling. From the results conclusions could be drawn about the adsorption abilities of the substances to the different surfaces.

    The barnacles were placed in hydrophobic as well as hydrophilic Petri dishes that had been incubated with ivermectin, spinosad or barettin. After four to six days the larva was counted to analyze the settling. From the results conclusions could be drawn about the adsorption abilities of the substances to the different surfaces.

    To analyze the adsorption abilities, pieces of silicon oxide were prepared with hydrophobic and hydrophilic poly dimethyl siloxan groups, and albumine. The pieces were then analyzed with ellipsometry.

    The larva's mortality was very high in the first tests. It can be explained with them being stored too cold the first days, which might have caused their death. It might also be because of contamination from the net used to move the larva, since it was in contact with all the substances concentrations.

    The standard deviations from the ellipsometry tests are very high, most likely due to uneven adsorption of the substances to the surface. With more tests and measurements, more accurate results could have been sustained

    The purpose of this project is to analyze and study the absorption of the substances ivermectin, spinosad and barettin to hydrophobic and hydrophilic surfaces, and to analyze and study if the barnacle larva are effected when they try to settle on the treated surface.

    Incubation tests with barnacle larva in Petri dishes were performed as well as absorption tests on hydrophobic and hydrophilic surfaces which were tested with ellipsometry. To determine the surface thickness.

    The barnacles were placed in hydrophobic as well as hydrophilic Petri dishes that had been incubated with ivermectin, spinosad or barettin. After four to six days the larva was counted to analyze the settling. From the results conclusions could be drawn about the adsorption abilities of the substances to the different surfaces.

    The barnacles were placed in hydrophobic as well as hydrophilic Petri dishes that had been incubated with ivermectin, spinosad or barettin. After four to six days the larva was counted to analyze the settling. From the results conclusions could be drawn about the adsorption abilities of the substances to the different surfaces.

    To analyze the adsorption abilities, pieces of silicon oxide were prepared with hydrophobic and hydrophilic poly dimethyl siloxan groups, and albumine. The pieces were then analyzed with ellipsometry.

    The larva's mortality was very high in the first tests. It can be explained with them being stored too cold the first days, which might have caused their death. It might also be because of contamination from the net used to move the larva, since it was in contact with all the substances concentrations.

    The standard deviations from the ellipsometry tests are very high, most likely due to uneven adsorption of the substances to the surface. With more tests and measurements, more accurate results could have been sustained

  • 29.
    Bouwman, Henk
    et al.
    Northwest University, South Africa.
    Choong Kwe Yive, Nee Sun
    University of MAuritius.
    Kylin, Henrik
    Linköping University, The Tema Institute, Department of Water and Environmental Studies.
    Polder, Anushka
    Veterinary Institute, Norway.
    Organic pollutants in term eggs from Rodrigues Island – Indian Ocean.2012Conference paper (Other academic)
  • 30.
    Bouwman, Henk
    et al.
    Northwest University, South Africa.
    Kylin, Henrik
    Linköping University, The Tema Institute, Department of Water and Environmental Studies.
    van den Berg, Henk
    Wageningen University, South Africa.
    Bornman, Riana
    University of Pretoria, South Africa.
    Is precaution the way to manage the paradox of DDT use in malaria control?2012Conference paper (Other academic)
  • 31.
    Bouwman, Hindrik
    et al.
    North West University, South Africa .
    Kylin, Henrik
    Linköping University, The Tema Institute, Department of Water and Environmental Studies. Linköping University, Faculty of Arts and Sciences.
    Sereda, Barbara
    Plant Protect Research Institute, South Africa .
    Bornman, Riana
    University of Pretoria, South Africa .
    High levels of DDT in breast milk: Intake, risk, lactation duration, and involvement of gender2012In: Environmental Pollution, ISSN 0269-7491, E-ISSN 1873-6424, Vol. 170, 63-70 p.Article in journal (Refereed)
    Abstract [en]

    We investigated presence and levels of DDT in 163 breast milk samples from four South African villages where, in three of them, malaria is controlled with DDT-sprayed indoors. Mean Sigma DDT levels in breast milk were 18, 11, and 9.5 mg/kg mf (milk fat) from the three DDT-sprayed villages, respectively, including the highest Sigma DDT level ever reported for breast milk from South Africa (140 mg/kg mf). Understanding the causes for these differences would be informative for exposure reduction intervention. The Provisional Tolerable Daily Intake (PTDI) for DDT by infants, and the Maximum Residue Limit (MRL) were significantly exceeded. DDT had no effect on duration of lactation. There were indications (not significant) from DDT-sprayed villages that first-born female infants drink milk with more Sigma DDT than first-born male infants, and vice versa for multipara male and female infants, suggesting gender involvement on levels of DDT in breast milk - requiring further investigation.

  • 32.
    Bouwman, Hindrik
    et al.
    North West University, South Africa .
    Kylin, Henrik
    Linköping University, The Tema Institute, Department of Water and Environmental Studies. Linköping University, Faculty of Arts and Sciences.
    Sun Choong Kwet Yive, Nee
    Mauritian Wildlife Fdn, Mauritius .
    Loken, Katharina
    Norwegian School Vet Science, Norway .
    Utne Skaare, Janneche
    Norwegian School Vet Science, Norway .
    Polder, Anuschka
    Norwegian School Vet Science, Norway .
    First report of chlorinated and brominated hydrocarbon pollutants in marine bird eggs from an oceanic Indian Ocean island2012In: Environmental Research, ISSN 0013-9351, E-ISSN 1096-0953, Vol. 118, 53-64 p.Article in journal (Refereed)
    Abstract [en]

    We report for the first time levels of persistent organic pollutants in marine bird eggs from an oceanic island in the Indian Ocean, the worlds third largest ocean. Ten eggs each of the Common Noddy, also known as the Brown Noddy (Anous stolidus), and Sooty Tern (Sterna fuscata) were collected from Ile Cocos off the coast of the island of Rodrigues, located 560 km east of the island of Mauritius. Sigma PCBs had the highest levels (2.2 and 2.6 ng/g wm, wet mass; 20 and 19 ng/g lm, lipid mass) for common Noddy and Sooty Tern, respectively (and following), then Sigma DDT (1.9 and 3.1 ng/g wm; 17 and 23 ng/g lm), and mirex (0.96 and 0.69 ng/g wm; 8.7 and 5.0 ng/g lm). Sigma Chlordanes (0.094 and 0.15 ng/g wm; 0.48 and 0.73 ng/g lm) and Sigma toxaphenes (0.26 and 0.61 ng/g wm; 2.4 and 5.9 ng/g lm) are rare data for these compounds from this ocean. Brominated flame retardants were low (0.08 and 0.07 ng/g wm; 0.7 and 0.7 ng/g lm). Multivariate analyses indicated different contamination patterns in the prey items as Sooty Terns had significantly higher levels of mean Sigma chlordanes and Sigma toxaphenes, as well as CB105, -108 and -157. p,p-DDE had an association with thinner eggshells in the Sooty Tern. Although the contaminant levels were in all respects low, industrialisation, development on the periphery, commercial exploitation of the marine environment, and pollutants transferred over long distances by marine debris is likely to add to chemical pressure in this region. Monitoring changes in background levels of pollutants in remote regions will indicate such trends, and marine bird eggs from Rodrigues would be an excellent site.

  • 33.
    Broberg, Marina
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    FTIR method for analysis of synthesis gas2013Independent thesis Basic level (university diploma), 10,5 credits / 16 HE creditsStudent thesis
    Abstract [en]

    The research institute ETC in Piteå is working with energy technical research and development. Today, much work revolves around research about renewable sources for fuel. In one project, biomass such as wood pellet is heated up while producing synthesis gas. The synthesis gas is then analyzed using three different GC techniques. ETC wanted to be able to make all their analysis on one instrument and with a faster speed. They contacted the company Rowaco in Linköping for help with developing a method on FTIR for analysis of the synthesis gas and that has been the aim for this thesis. A method has been developed for analysis of water, carbon monoxide, carbon dioxide and methane. The results from this thesis show that the concentrations of the molecules in the synthesis gas are outside the calibration curved that has been made and that the high concentrations give much interference to other molecules. The thesis also shows that many areas in the spectrum from the process are roof absorbers and there is also a contamination of water and carbon dioxide in the system. Suggested improvements are to find the source for the contamination, to develop calibration points with higher concentrations, to reduce the length of the gas cell and to dilute the gas before entering the FTIR. 

  • 34.
    Broberg, Mikael
    Linköping University, Department of Physics, Chemistry and Biology.
    Protein i korn: En torkstudie utförd med etablerade analysmetoder på tre kornsorter2010Independent thesis Basic level (degree of Bachelor), 10,5 credits / 16 HE creditsStudent thesis
    Abstract [en]

    A study was performed to evaluate whether established methods of analysis of protein content in barley (Kjeldahl, Dumas, or NIT (short for Near Infrared Transmittance)) gives different results for wet and dried barley. This was carried out because there are concerns regarding the well-worn NIT prediction model giving different results for these conditions and that such an error causes significant price fluctuations on the market. By performing analyses of samples, both before and after drying, of the three different barley varieties Tipple, Prestige, and Quench, with all the techniques, data was obtained that could be analyzed statistically. The study showed that the NIT prediction model gives results for wet barley that is about 0.29 percentage points higher compared to dried barley. This difference was also statistically significant when a t-test was performed. The same difference was substantially smaller for Kjeldahl and Dumas and furthermore not statistically significant.

    When the difference between the different barley varieties is studied a deviation of 0.34 percentage points was obtained for Tipple, 0.18 percentage points for Prestige, and 0.30 percentage points for Quench. NIT, thereby, gave results with greatest deviation when wet Tipple was analyzed. When t-tests were performed for each barley variety, it was found that results for all varieties differ significantly between wet and dry barley.

    A study of the difference between the crude protein content determination by Kjeldahl and Dumas was also performed by calculating the mean differences between the various methods of determination. The average difference in crude protein determination was calculated to 0.07 percentage points.

  • 35.
    Carlsson, Anders
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, The Institute of Technology.
    Identification of potential plasma biomarkers of inflammation in farmers with musculoskeletal disorders: A proteomic study2012Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In this thesis we look for potential chronic inflammation biomarkers because studies have shown that farmers with musculoskeletal disorders might be affected by the environment to develop musculoskeletal disorders. Animal farmers are highly exposed to dust, aerosols, molds and other toxins in the air and environment leading to musculoskeletal disorders, respiratory disorders, airway symptoms and febrile reactions. There is reason to believe that the farmers have a constant or chronic inflammation that develops into musculoskeletal disorders. By using a proteomic approach with Two-dimensional Gel Electrophoresis and silver staining our goal was to find biomarkers by quantifying protein spots that differ significantly from farmers with musculoskeletal disorders compared to rural controls. In our study we found 8 significant proteins, two from Alpha-2-HS-glycoprotein, one from Apolipoprotein A1, three from Haptoglobin, one from Hemopexin and 1 from Antithrombin. All 5 proteins are involved in inflammation response in some way and some proteins are linked to chronic inflammation. Out of the 5 proteins Alpha-2-HS-glycoprotein, Apolipoprotein A1 and Hemopexin seem like the most likely proteins to investigate further as potential inflammation biomarkers.

  • 36.
    Carlsson, Andreas
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, Faculty of Science & Engineering. Swedish National Forens Centre NFC, Linkoping, Sweden.
    Synthesis and spectroscopic characterization of emerging synthetic cannabinoids and cathinones2016Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    The application of different analytical techniques is fundamental in forensic drug analysis. In the wake of the occurrence of large numbers of new psychoactive substances possessing similar chemical structures as already known ones, focus has been placed on applied criteria for their univocal identification. These criteria vary, obviously, depending on the applied technique and analytical approach. However, when two or more substances are proven to have similar analytical properties, these criteria no longer apply, which imply that complementary techniques have to be used in their differentiation.

    This work describes the synthesis of some structural analogues to synthetic cannabinoids and cathinones based on the evolving patterns in the illicit drug market. Six synthetic cannabinoids and six synthetic cathinones were synthesized, that, at the time for this study, were not as yet found in drug seizures. Further, a selection of their spectroscopic data is compared to those of already existing analogues; mainly isomers and homologues. The applied techniques were mass spectrometry (MS), Fourier transformed infrared (FTIR, gas phase) spectroscopy and nuclear magnetic resonance (NMR) spectroscopy. In total, 59 different compounds were analyzed with the  selected techniques.

    The results from comparison of spectroscopic data showed that isomeric substances may in some cases be difficult to unambiguously identify based only on their GC-MS EI spectra. On the other hand, GC-FTIR demonstrated more distinguishable spectra. The spectra for the homologous compounds showed however, that the GC-FTIR technique was less successful compared to GC-MS. Also a pronounced fragmentation pattern for some of the cathinones was found.

    In conclusion, this thesis highlights the importance of using complementary techniques for the univocal identification of synthetic cannabinoids and cathinones. By increasing the number of analogues investigated, the more may be learnt about the capabilities of different techniques for structural differentiations, and thereby providing important identification criteria leading to trustworthy forensic evidence.

    List of papers
    1. Prediction of designer drugs: synthesis and spectroscopic analysis of synthetic cannabinoid analogues of 1H-indol-3-yl(2,2,3,3-tetramethylcyclopropyl) methanone and 1H-indol-3-yl(adamantan-1-yl)methanone
    Open this publication in new window or tab >>Prediction of designer drugs: synthesis and spectroscopic analysis of synthetic cannabinoid analogues of 1H-indol-3-yl(2,2,3,3-tetramethylcyclopropyl) methanone and 1H-indol-3-yl(adamantan-1-yl)methanone
    Show others...
    2016 (English)In: Drug Testing and Analysis, ISSN 1942-7603, E-ISSN 1942-7611, Vol. 8, no 10, 1015-1029 p.Article in journal (Refereed) Published
    Abstract [en]

    In this work, emergence patterns of synthetic cannabinoids were utilized in an attempt to predict those that may appear on the drug market in the future. Based on this information, two base structures of the synthetic cannabinoid analogues - (1H-indol-3-yl (2,2,3,3-tetramethylcyclopropyl) methanone and 1H-indol-3-yl(adamantan-1-yl)methanone) - together with three substituents butyl, 4-fluorobutyl and ethyl tetrahydropyran - were selected for synthesis. This resulted in a total of six synthetic cannabinoid analogues that to the authors knowledge have not yet appeared on the drug market. Spectroscopic data, including nuclearmagnetic resonance (NMR), mass spectrometry (MS), and Fourier transforminfrared (FTIR) spectroscopy (solid and gas phase), are presented for the synthesized analogues and some additional related cannabinoids. In this context, the suitability of the employed techniques for the identification of unknowns is discussed and the use of GC-FTIR as a secondary complementary technique to GC-MS is addressed. Examples of compounds that are difficult to differentiate by their mass spectra, but can be distinguished based upon their gas phase FTIR spectra are presented. Conversely, structural homologueswhere mass spectra aremore powerful than gas phase FTIR spectra for unambiguous assignments are also exemplified. This work further emphasizes that a combination of several techniques is the key to success in structural elucidations. Copyright (C) 2015 John Wiley amp; Sons, Ltd.

    Place, publisher, year, edition, pages
    WILEY-BLACKWELL, 2016
    Keyword
    drug analysis; proactive; synthetic cannabinoids; synthesis; mass spectrometry
    National Category
    Pharmaceutical Sciences
    Identifiers
    urn:nbn:se:liu:diva-132473 (URN)10.1002/dta.1904 (DOI)000384806400003 ()26526273 (PubMedID)
    Note

    Funding Agencies|Swedish Contingencies Agency (MSB)

    Available from: 2016-11-13 Created: 2016-11-12 Last updated: 2016-11-24
  • 37.
    Chen, Chang
    et al.
    Huazhong University of Science and Technology, Peoples R China.
    Wohlfarth, Ariane
    Linköping University, Department of Medical and Health Sciences, Division of Drug Research. Linköping University, Faculty of Medicine and Health Sciences. National Board Forens Med, Linköping, Sweden.
    Xu, Hui
    Maternal and Child Health Hospital Hubei Prov, Peoples R China.
    Su, Dan
    Jiangxi University of Tradit Chinese Med, Peoples R China.
    Wang, Xin
    MassDefect Technology, NJ 08540 USA.
    Jiang, Hongliang
    Huazhong University of Science and Technology, Peoples R China.
    Feng, Yulin
    Jiangxi University of Tradit Chinese Med, Peoples R China.
    Zhu, Mingshe
    Bristol Myers Squibb, NJ 08543 USA.
    Untargeted screening of unknown xenobiotics and potential toxins in plasma of poisoned patients using high-resolution mass spectrometry: Generation of xenobiotic fingerprint using background subtraction2016In: Analytica Chimica Acta, ISSN 0003-2670, E-ISSN 1873-4324, Vol. 944, 37-43 p.Article in journal (Refereed)
    Abstract [en]

    A novel analytical workflow was developed and applied for the detection and identification of unknown xenobiotics in biological samples. High-resolution mass spectrometry (HRMS)-based data-independent MSE acquisition was employed to record full scan MS and fragment spectral datasets of test and control samples. Then, an untargeted data-mining technique, background subtraction, was utilized to find xenobiotics present only in test samples. Structural elucidation of the detected xenobiotics was accomplished by database search, spectral interpretation, and/or comparison with reference standards. Application of the workflow to analysis of unknown xenobiotics in plasma samples collected from four poisoned patients led to generation of xenobiotic profiles, which were regarded as xenobiotic fingerprints of the individual samples. Among 19 xenobiotics detected, 11 xenobiotics existed in a majority of the patients plasma samples, thus were considered as potential toxins. The follow-up database search led to the tentative identification of azithromycin (X5), alpha-chaconine (X9) and penfluridol (X12). The identity of X12 was further confirmed with its reference standard. In addition, one xenobiotic component (Y5) was tentatively identified as a penfluridol metabolite. The remaining unidentified xenobiotics listed in the xenobiotic fingerprints can be further characterized or identified in retrospective analyses after their spectral data and/or reference compounds are available. This HRMS-based workflow may have broad applications in the detection and identification of unknown xenobiotics in individual biological samples, such as forensic and toxicological analysis and sport enhancement drug screening. (C) 2016 Elsevier B.V. All rights reserved.

  • 38.
    Cheung, Kwan Yee
    et al.
    National University of Singapore.
    Mak, Wing Cheung
    National University of Singapore.
    Trau, Dieter
    National University of Singapore.
    Reusable optical bioassay platform with permeability-controlled hydrogel pads for selective saccharide detection2008In: Analytica Chimica Acta, ISSN 0003-2670, E-ISSN 1873-4324, Vol. 607, no 2, 204-210 p.Article in journal (Refereed)
    Abstract [en]

    A reusable optical bioassay platform using permeability-controlled hydrogel pads for selective saccharide detection has been developed. An optical glucose detection assay based on fluorescence resonance energy transfer (FRET) between dye-labeled dextran and Concanavalin A (ConA) was incorporated into hydrogel pads by entrapment. The hydrogel pads are constructed from hemispherical hydrogel attached onto hydrophobic surfaces of a microtiter plate. The resulted hemispherical hydrogel pads entrapping the sensing biological materials were further surface coated with polyelectrolyte multilayers through a Layer-by-Layer (LbL) self-assembly process to create a permeability-controlled membrane with nanometer thickness. The selective permeable LbL film deposited on the hydrogel surface allows small molecular weight analytes to diffuse into the hydrogel pads while the large molecular weight sensing biological molecules are immobilized. An encapsulation efficiency of 75% for the ConA/Dextran complex within the coated hydrogel pads was achieved and no significant leakage of the complex was observed. Glucose calibration curve with linear range from 0 to 10 mM glucose was obtained. Selective permeability of the hydrogel pads has been demonstrated by measurement of saccharides with various molecular weights. The LbL hydrogel pads could selectively detect monosaccharides (glucose, MW = 180) and disaccharides (sucrose, MW = 342) while polysaccharides (dextran, MW ∼ 70 kDa) cannot diffuse through the LbL layer and are excluded. LbL hydrogel pads allow regeneration of the FRET system with good signal reproducibility of more than 90% to construct a reusable and reagentless optical bioassay platform.

  • 39.
    Colnerud Nilsson, Emma
    Linköping University, Department of Physics, Chemistry and Biology.
    Database for targeted drug screening with Liquid Chromatography - Time-Of-Flight Mass Spectrometry, (LC-TOFMS)2010Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Today there are no fully general analytical techniques available for detection and confirmation of known and unknown substances in toxicological screening, further tools are therefore needed. The development of mass spectrometry with time-of-flight (TOF) detection is promising but there are still areas to be further developed and evaluated, both instrumentation and applications.

    During 2009 The National Board of Forensic Medicine-Department of Forensic Genetics and Forensic Toxicology, (RMV) started cooperation with the instrumentation company Waters (Manchester, UK) and the Department of Clinical Pharmacology (KI, Solna) evaluating a new TOF-instrument for toxicological screening. My assignment as a part of this project has been to create a limited and relevant database of drugs and toxics in Excel, including monoisotopic mass, used when screening for pharmaceutical substances and their metabolites most probable to be found in Swedish autopsy material.

    A limited database has been developed based on information from several sources, it ended up in 875 analytes and metabolites. A limited but complete database is more reliable in practise than a big database, by means of a lower frequency of isobars and more information included (e.g. retention time from liquid chromatography) making analysis faster. Commercial databases are generally theoretical, lacking information about for example retention time that often is an important criterion for identification.

  • 40.
    Colnerud Nilsson, Emma
    Linköping University, Department of Biomedicine and Surgery.
     Salivary cortisol and post traumatic stress symptoms  : -a ten year follow-up of Swedish UN soldiers after a 6 months mission in Bosnia2009Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This is to my knowledge the first time a ten-year follow-up study of salivary cortisol concentrations measured by immunoassays in relation to posttraumatic symptoms according to the Impact of Event Scale (IES) is made. The study was performed on 78 Swedish UN soldiers after a 6-months mission in the former republic of Yugoslavia. Follow-up investigations were performed six months, twelve months and ten years after their return to Sweden. Morning and evening salivary cortisol concentrations were determined by radioimmunoassay (RIA) and enzyme-linked immunoassay (EIA) and subjective posttraumatic avoidance and intrusion symptoms were measured with the IES (see Appendix I).

     

    This study concerns the methodological description of the EIA for determination of salivary cortisol and the comparison of the results from all three follow-up investigations. Post-traumatic stress symptoms according to IES (intrusion subscale and total score) increased significantly over ten years of time. There was an significant interrelationship between the change in both morning and evening salivary cortisol concentrations, measured with immunoassays, and changes in self-rated posttraumatic intrusive symptoms, according to IES, during ten years follow-up, after a six months mission in Bosnia in the way that salivary cortisol concentrations showed a tendency to decrease over ten years of time in subjects with a higher IES score. The rise in morning salivary cortisol, from awakening until 30 minutes later, was significantly correlated with the ratings of posttraumatic stress symptoms according to the IES ten years after the mission.   

  • 41.
    Comina, German
    et al.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, Faculty of Science & Engineering.
    Suska, Anke
    Linköping University, Department of Physics, Chemistry and Biology, Chemical and Optical Sensor Systems. Linköping University, Faculty of Science & Engineering.
    Filippini, Daniel
    Linköping University, Department of Physics, Chemistry and Biology, Chemical and Optical Sensor Systems. Linköping University, Faculty of Science & Engineering.
    A 3D printed device for quantitative enzymatic detection using cell phones2016In: Analytical Methods, ISSN 1759-9660, E-ISSN 1759-9679, Vol. 8, no 32, 6135-6142 p.Article in journal (Refereed)
    Abstract [en]

    A disposable device for quantitative enzymatic detection capable of coupling illumination and image readouts from cell phones is demonstrated. The device integrates a calibration range for glutamate detection, utilizes the phone screen as a light source, and provides the necessary actuation for autonomous operation. Custom made optics required to couple to the cell phone camera is accomplished using affordable stereolithography (SLA) 3D printers. The described method does not involve polishing, requires only two steps from design to implementation, and can be locally applied to 3D printed lab-on-a-chip (LOC) prototypes, using the same materials. Optical finishing and dimensional variability within 2% were achieved, supporting entirely arbitrary geometries for elements larger than 400 mm in radius. Representative fabrication times and costs were 20 min and $0.50 USD per prototype.

  • 42.
    Concheiro, Marta
    et al.
    NIDA, MD 21224 USA.
    Castaneto, Marisol
    NIDA, MD 21224 USA; University of Maryland Baltimore County, MD 21228 USA.
    Kronstrand, Robert
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Medicine and Health Sciences. National Board Forens Med, Department Forens Genet and Forens Toxicol, Linkoping, Sweden.
    Huestis, Marilyn A.
    NIDA, MD 21224 USA.
    Simultaneous determination of 40 novel psychoactive stimulants in urine by liquid chromatography-high resolution mass spectrometry and library matching2015In: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 1397, 32-42 p.Article in journal (Refereed)
    Abstract [en]

    The emergence of novel psychoactive substances is an ongoing challenge for analytical toxicologists. Different analogs are continuously introduced in the market to circumvent legislation and to enhance their pharmacological activity. Although detection of drugs in blood indicates recent exposure and link intoxication to the causative agent, urine is still the most preferred testing matrix in clinical and forensic settings. We developed a method for the simultaneous quantification of 8 piperazines, 4 designer amphetamines and 28 synthetic cathinones and 4 metabolites, in urine by liquid chromatography coupled to high-resolution mass spectrometry (LC-HRMS). Data were acquired in full scan and data dependent MS2 mode. Compounds were quantified by precursor ion exact mass, and confirmed by product ion spectra library matching, taking into account product ions exact mass and intensities. One-hundred pi, urine was subjected to solid phase cation exchange extraction (SOLA SCX). The chromatographic reverse-phase separation was achieved with gradient mobile phase of 0.1% formic acid in water and in acetonitrile in 20 min. The assay was linear from 2.5 or 5 to 500 mu g/L. Imprecision (n = 15) was less than15.4%, and accuracy (n = 15) 84.2-118.5%. Extraction efficiency was 51.2-111.2%, process efficiency 57.7-104.9% and matrix effect ranged from -41.9% to 238.5% (CV less than 23.3%, except MDBZP CV less than 34%). Authentic urine specimens (n = 62) were analyzed with the method that provides a comprehensive confirmation for 40 new stimulant drugs with specificity and sensitivity.

  • 43.
    Di Natale, Corrado
    et al.
    University of Rome Tor Vergata, via del Politecnico 1, 00133 Roma, Italy.
    Buchholt, Kristina
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, Faculty of Science & Engineering.
    Martinelli, E
    University of Rome Tor Vergata, via del Politecnico 1, 00133 Roma, Italy.
    Paolesse, Roberto
    University of Rome Tor Vergata, via del Politecnico 1, 00133 Roma, Italy.
    D´Amico, Arnaldo
    University of Rome Tor Vergata, via del Politecnico 1, 00133 Roma, Italy.
    Lundström, Ingemar
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, Faculty of Science & Engineering.
    Lloyd Spetz, Anita
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, Faculty of Science & Engineering.
    Investigation of the selectivity properties of metalloporphyrines self-assembled-monolayers on QMB and FET transducers2006In: Proc Eurosensors XX, 2006, T1A-P11Conference paper (Refereed)
    Abstract [en]

    Progresses of synthetic chemistry methodologies have allowed the preparation of a great variety of artificial receptors that are particularly appealing for chemical sensor development. In this paper, we investigate and compare the properties of gas sensors based on two types of devices, quartz microbalances (QMBs) and field effect transistors (FETs), which give the means to exploit the molecular recognition events occurring in non-conductive sensing layers formed by a thiol-modified cobalt tetraphenylporphyrin (CoTPPSH). Since QMB is sensitive to mass and FET is sensitive to electric dipoles, the resulting sensors are expected to exhibit different sensitivities and selectivities, although both based on the same sensing layer. In particular we show that the high sensitivity of CoTPPSH-coated FETs towards CO and NO is a consequence of the significant CoTPPSH electric dipole change after the gas coordination to the metal centre.

  • 44.
    Diacci, Chiara
    et al.
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering. University of Modena and Reggio Emilia, Italy.
    Berto, Marcello
    University of Modena and Reggio Emilia, Italy; University of Ferrara, Italy.
    Di Lauro, Michele
    University of Modena and Reggio Emilia, Italy.
    Bianchini, Elena
    University of Modena and Reggio Emilia, Italy.
    Pinti, Marcello
    University of Modena and Reggio Emilia, Italy.
    Simon, Daniel
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Biscarini, Fabio
    University of Modena and Reggio Emilia, Italy.
    Bortolotti, Carlo A.
    University of Modena and Reggio Emilia, Italy.
    Label-free detection of interleukin-6 using electrolyte gated organic field effect transistors2017In: Biointerphases, ISSN 1934-8630, E-ISSN 1559-4106, Vol. 12, no 5, 05F401Article in journal (Refereed)
    Abstract [en]

    Cytokines are small proteins that play fundamental roles in inflammatory processes in the human body. In particular, interleukin (IL)-6 is a multifunctional cytokine, whose increased levels are associated with infection, cancer, and inflammation. The quantification of IL-6 is therefore of primary importance in early stages of inflammation and in chronic diseases, but standard techniques are expensive, time-consuming, and usually rely on fluorescent or radioactive labels. Organic electronic devices and, in particular, organic field-effect transistors (OFETs) have been proposed in the recent years as novel platforms for label-free protein detection, exploiting as sensing unit surface-immobilized antibodies or aptamers. Here, the authors report two electrolyte-gated OFETs biosensors for IL-6 detection, featuring monoclonal antibodies and peptide aptamers adsorbed at the gate. Both strategies yield biosensors that can work on a wide range of IL-6 concentrations and exhibit a remarkable limit of detection of 1 pM. Eventually, electrolyte gated OFETs responses have been used to extract and compare the binding thermodynamics between the sensing moiety, immobilized at the gate electrode, and IL-6. (C) 2017 American Vacuum Society.

  • 45.
    Ekedahl, Lars-Gunnar
    et al.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Eriksson, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Chemical and Optical Sensor Systems. Linköping University, Faculty of Science & Engineering.
    Lundström, Ingemar
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, Faculty of Science & Engineering.
    Hydrogen sensing mechanisms of metal insulator interfaces1998In: Accounts of Chemical Research, ISSN 0001-4842, E-ISSN 1520-4898, Vol. 31, no 5, 249-256 p.Article in journal (Refereed)
    Abstract [en]

    The hydrogen sensitivity of palladium-silicon dioxidesilicon (Pd-MOS) structures was demonstrated about 25 years ago. One of the most interesting features of the Pd-MOS device as a hydrogen sensor is its very large dynamic pressure range. Such devices are now used in several practical applications and in commercially available equipment, both as single sensors and in sensor arrays. We recall that the hydrogen sensitivity of the device occurs due to a hydrogen induced polarization at the Pd-SiO2 interface as schematically shown in Figure 1. During the years, several types of devices have been developed, both with insulators other than silicon dioxide and catalytic metals other than palladium. Furthermore, it has been demonstrated that sensors with thin, discontinuous catalytic metals can detect molecules, like ammonia, which are not detected by sensors with thick continuous palladium gates. 1-3 Although several insulators have been used in hydrogen sensitive Pd-insulator-semiconductor

  • 46.
    Elhag, Sami
    Linköping University, Department of Science and Technology. Linköping University, Faculty of Science & Engineering.
    Chemically Modified Metal Oxide Nanostructures Electrodes for Sensing and Energy Conversion2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The goal of this thesis is the development of scalable, low cost synthesis of metal oxide nanostructures based electrodes and to correlate the chemical modifications with their energy conversion performance. Methods in energy conversion in this thesis have focused on two aspects; a potentiometric chemical sensor was used to determine the analytical concentration of some components of the analyte solution such as dopamine, glucose and glutamate molecules. The second aspect is to fabricate a photo-electrochemical (PEC) cell. The biocompatibility, excellent electro-catalytic activities and fast electron transfer kinetics accompanied with a high surface area to volume ratio; are properties of some metal oxide nanostructures that of a potential for their use in energy conversion. Furthermore, metal oxide nanostructures based electrode can effectively be improved by the physical or a chemical modification of electrode surface. Among these metal oxide nanostructures are cobalt oxide (Co3O4), zinc oxide (ZnO), and bismuth-zincvanadate (BiZn2VO6) have all been studied in this thesis. Metal oxide nanostructures based electrodes are fabricated on gold-coated glass substrate by low temperature (< 100 0C) wet chemicalapproach. X-ray diffraction, x-ray photoelectron spectroscopy and scanning electron microscopy were used to characterize the electrodes while ultraviolet-visible absorption and photoluminescence were used to investigate the optical properties of the nanostructures. The resultant modified electrodes were tested for their performance as chemical sensors and for their efficiency in PEC activities. Efficient chemically modified electrodes were demonstrated through doping with organic additives like anionic, nonionic or cationic surfactants. The organic additives are showing a crucial role in the growth process of metal oxide nanocrystals and hence can beused to control the morphology. These organic additives act also as impurities that would significantly change the conductivity of the electrodes. However, no organic compounds dependence was observed to modify the crystallographic structure. The findings in this thesis indicate the importance of the use of controlled nanostructures morphology for developing efficient functional materials.

    List of papers
    1. Incorporating beta-Cyclodextrin with ZnO Nanorods: A Potentiometric Strategy for Selectivity and Detection of Dopamine
    Open this publication in new window or tab >>Incorporating beta-Cyclodextrin with ZnO Nanorods: A Potentiometric Strategy for Selectivity and Detection of Dopamine
    2014 (English)In: Sensors, ISSN 1424-8220, Vol. 14, no 1, 1654-1664 p.Article in journal (Refereed) Published
    Abstract [en]

    We describe a chemical sensor based on a simple synthesis of zinc oxide nanorods (ZNRs) for the detection of dopamine molecules by a potentiometric approach. The polar nature of dopamine leads to a change of surface charges on the ZNR surface via metal ligand bond formation which results in a measurable electrical signal. ZNRs were grown on a gold-coated glass substrate by a low temperature aqueous chemical growth (ACG) method. Polymeric membranes incorporating beta-cyclodextrin (beta-CD) and potassium tetrakis (4-chlorophenyl) borate was immobilized on the ZNR surface. The fabricated electrodes were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques. The grown ZNRs were well aligned and exhibited good crystal quality. The present sensor system displays a stable potential response for the detection of dopamine in 10(-2) mol.L-1 acetic acid/sodium acetate buffer solution at pH 5.45 within a wide concentration range of 1 x 10(-6) M-1 x 10(-1) M, with sensitivity of 49 mV/decade. The electrode shows a good response time (less than 10 s) and excellent repeatability. This finding can contribute to routine analysis in laboratories studying the neuropharmacology of catecholamines. Moreover, the metal-ligand bonds can be further exploited to detect DA receptors, and for bio-imaging applications.

    Place, publisher, year, edition, pages
    MDPI, 2014
    Keyword
    ZnO nanorods; dopamine; potentiometric response; selectivity; stability; repeatability
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-107470 (URN)10.3390/s140101654 (DOI)000336039100087 ()
    Available from: 2014-06-12 Created: 2014-06-12 Last updated: 2017-02-02Bibliographically approved
    2. Habit-modifying additives and their morphological consequences on photoluminescence and glucose sensing properties of ZnO nanostructures, grown via aqueous chemical synthesis
    Open this publication in new window or tab >>Habit-modifying additives and their morphological consequences on photoluminescence and glucose sensing properties of ZnO nanostructures, grown via aqueous chemical synthesis
    Show others...
    2015 (English)In: Vacuum, ISSN 0042-207X, E-ISSN 1879-2715, Vol. 116, 21-26 p.Article in journal (Refereed) Published
    Abstract [en]

    Generally, the anisotropic shape of inorganic nano-crystal can be influenced by one or more of different parameters i.e. kinetic energy barrier, temperature, time, and the nature of the capping molecules. Here, different surfactants acting as capping molecules were used to assist the aqueous chemical growth of zinc oxide (ZnO) nanostructures on Au coated glass substrates. The morphology, crystal quality and the photoluminescence (PL) properties of the ZnO nanostructures were investigated. The PL properties of the prepared ZnO nanostructures at room temperature showed a dominant UV luminescence peak, while the "green yellow" emissions were essentially suppressed. Moreover, the ZnO nanostructures were investigated for the development of a glucose biosensor. An adsorbed molecule has direct contribution on the glucose oxidase/ZnO/Au sensing properties. We show that the performance of a ZnO-based biosensor can be improved by tailoring the properties of the ZnO biomolecule interface through engineering of the morphology, effective surface area, and adsorption capability.

    Place, publisher, year, edition, pages
    Elsevier, 2015
    Keyword
    ZnO nanostructures; Cationic and anionic molecules; PL spectra; Glucose sensitivity
    National Category
    Physical Chemistry
    Identifiers
    urn:nbn:se:liu:diva-119245 (URN)10.1016/j.vacuum.2015.02.026 (DOI)000354582900004 ()
    Note

    Funding Agencies|University of Kordofan Grant, El-Obeid, Kordofan Sudan [700]

    Available from: 2015-06-15 Created: 2015-06-12 Last updated: 2017-02-02
    3. Effect of Urea on the Morphology of Co3O4 Nanostructures and Their Application for Potentiometric Glucose Biosensor
    Open this publication in new window or tab >>Effect of Urea on the Morphology of Co3O4 Nanostructures and Their Application for Potentiometric Glucose Biosensor
    Show others...
    2014 (English)In: Electroanalysis, ISSN 1040-0397, E-ISSN 1521-4109, Vol. 26, no 8, 1773-1781 p.Article in journal (Refereed) Published
    Abstract [en]

    In this study, an effect of different concentrations of urea on the morphology of cobalt oxide (Co3O4) nanostructures was investigated. The Co3O4 nanostructures are fabricated on gold coated glass substrate by the hydrothermal method. The morphological and structural characterization was performed by scanning electron microscopy, and X-ray diffraction techniques. The Co3O4 nanostructures exhibit morphology of flowers-like and have comprised on nanowires due to the increasing amount of urea. The nanostructures were highly dense on the substrate and possess a good crystalline quality. The Co3O4 nanostructures were successfully used for the development of a sensitive glucose biosensor. The presented glucose biosensor detected a wide range of glucose concentrations from 1 x 10(-6) M to 1 x 10(-2) M with sensitivity of a -56.85 mV/decade and indicated a fast response time of less than 10 s. This performance could be attributed to the heterogeneous catalysis effect at glucose oxidase enzyme, nanoflowers, and nanowires interfaces, which have enhanced the electron transfer process on the electrode surface. Moreover, the reproducibility, repeatability, stability and selectivity were also investigated. All the obtained results indicate the potential use of the developed glucose sensor for monitoring of glucose concentrations at drugs, human serum and food industry related samples.

    Place, publisher, year, edition, pages
    Wiley-VCH Verlagsgesellschaft, 2014
    Keyword
    Nanostructures; Hydrothermal method; Glucose biosensor
    National Category
    Electrical Engineering, Electronic Engineering, Information Engineering
    Identifiers
    urn:nbn:se:liu:diva-110486 (URN)10.1002/elan.201400116 (DOI)000340557700016 ()
    Available from: 2014-09-15 Created: 2014-09-12 Last updated: 2017-02-02Bibliographically approved
    4. Dopamine wide range detection sensor based on modified Co3O4 nanowires electrode
    Open this publication in new window or tab >>Dopamine wide range detection sensor based on modified Co3O4 nanowires electrode
    Show others...
    2014 (English)In: Sensors and actuators. B, Chemical, ISSN 0925-4005, Vol. 203, 543-549 p.Article in journal (Refereed) Published
    Abstract [en]

    Ultra-thin cobalt oxide (Co3O4) nanowires grown on gold coated glass substrates by the hydrothermal chemical deposition and have been used as a wide range dopamine potentiometric sensor. An anionic surfactant ( sodium dodecylbenzenesulfonate) was used to achieve assisted growth procedure. Moreover, a polymeric membrane containing polyvinyl chloride as plasticized polymer, p-cyclodextrin as ionophore, and potassium tetrakis (4-chlorophenyl) borate as ionic additive were immobilized on the Co3O4 nanostructures through electrostatic adsorption method. X-ray diffraction, X-ray photoelectron spectroscopy, and scanning electron microscopy were used to characterize the electrodes while ultraviolet-visible absorption was used to investigate the band gap of the Co3O4 nanostructures. The structural characterization showed a cubic crystalline, pure phase, and nanowires morphology of the Co3O4. However, the morphology is altered when the surfactant concentration has been changed. The Co3O4 chemical modified electrodes were used in potentiometric measurements for dopamine in a 10(-2) M acetic acid/sodium acetate solution having a pH of 5.45. For dopamine range from 10(-9) M to 10(-2) M, the potential response of the sensor electrode was linear with a slope of 52 mV/decade. The wide range and high sensitivity of the modified Co3O4 nanowires based sensor for dopamine is attributed to the defects on the metal oxide that is dictated by the used surfactant along with the high surface area-to-volume ratio.

    Place, publisher, year, edition, pages
    Elsevier, 2014
    Keyword
    Potentiometric sensor; Chemically modified electrode; Surfactant; Dopamine chemical sensor
    National Category
    Electrical Engineering, Electronic Engineering, Information Engineering Physical Sciences
    Identifiers
    urn:nbn:se:liu:diva-111254 (URN)10.1016/j.snb.2014.07.028 (DOI)000341455400072 ()
    Available from: 2014-10-15 Created: 2014-10-14 Last updated: 2017-02-02Bibliographically approved
    5. Efficient Donor Impurities in ZnO Nanorods by Polyethylene Glycol for Enhanced Optical and Glutamate Sensing Properties
    Open this publication in new window or tab >>Efficient Donor Impurities in ZnO Nanorods by Polyethylene Glycol for Enhanced Optical and Glutamate Sensing Properties
    Show others...
    2016 (English)In: Sensors, ISSN 1424-8220, E-ISSN 1424-8220, Vol. 16, no 2Article in journal (Refereed) Published
    Abstract [en]

    In this paper, we show that the possibility of using polyethylene glycol (EG) as a hydrogen source and it is used to assist the hydrothermal synthesis of ZnO nanorods (ZNRs). EG doping in ZNRs has been found to significantly improve their optical and chemical sensing characteristics toward glutamate. The EG was found to have no role on the structural properties of the ZNRs. However, the x-ray photoelectron spectroscopy (XPS) suggests that the EG could induce donor impurities effect in ZnO. Photoluminescence (PL) and UV-Vis. spectra demonstrated this doping effect. Mott-Schottky analysis at the ZNRs/electrolyte interface was used to investigate the charge density for the doped ZNRs and showed comparable dependence on the used amount of EG. Moreover, the doped ZNRs were used in potentiometric measurements for glutamate for a range from 10(-6) M to 10(-3) M and the potential response of the sensor electrode was linear with a slope of 91.15 mV/decade. The wide range and high sensitivity of the modified ZNRs based glutamate biosensor is attributed to the doping effect on the ZNRs that is dictated by the EG along with the high surface area-to-volume ratio. The findings in the present study suggest new avenues to control the growth of n-ZnO nanostructures and enhance the performance of their sensing devices.

    Place, publisher, year, edition, pages
    MDPI AG, 2016
    Keyword
    potentiometric sensor; ZnO nanorods; glutamate; doping
    National Category
    Electrical Engineering, Electronic Engineering, Information Engineering Chemical Sciences Physical Sciences
    Identifiers
    urn:nbn:se:liu:diva-126849 (URN)10.3390/s16020222 (DOI)000371787800096 ()26861342 (PubMedID)
    Note

    Funding Agencies|University of Kordofan, El-Obeid, Kordofan Sudan [700]

    Available from: 2016-04-05 Created: 2016-04-05 Last updated: 2017-02-02
    6. Low-temperature growth of polyethylene glycol-doped BiZn2VO6 nanocompounds with enhanced photoelectrochemical properties
    Open this publication in new window or tab >>Low-temperature growth of polyethylene glycol-doped BiZn2VO6 nanocompounds with enhanced photoelectrochemical properties
    Show others...
    2017 (English)In: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 5, no 3, 1112-1119 p.Article in journal (Refereed) Published
    Abstract [en]

    We demonstrate scalable, low-cost and low-temperature (<100 °C) aqueous chemical growth of bismuth–zinc vanadate (BiZn2VO6) nanocompounds by BiVO4 growth on ZnO nanobelts (NBs). The nanocompounds were further doped with polyethylene glycol (PEG) to tune the electronic structure of the materials, as a means to lower the charge carrier recombination rate. The chemical composition, morphology, and detailed nanostructure of the BiZn2VO6 nanocompounds were characterized. They exhibit rice-like morphology, are highly dense on the substrate and possess a good crystalline quality. Photoelectrochemical characterization in 0.1 M lithium perchlorate in carbonate propylene shows that BiZn2VO6 nanocompounds are highly suitable as anodes for solar-driven photoelectrochemical applications, providing significantly better performance than with only ZnO NBs. This performance could be attributed to the heterogeneous catalysis effect at nanocompound and ZnO NB interfaces, which have enhanced the electron transfer process on the electrode surface. Furthermore, the charge collection efficiency could be significantly improved through PEG doping of nanocompounds. The photocurrent density of PEG-doped BiZn2VO6 nanocompounds reached values of 2 mA cm−2 at 1.23 V (vs. Ag/AgCl), over 60% larger than that of undoped BiZn2VO6 nanocompounds. Photoluminescence emission experiments confirmed that PEG plays a crucial role in lowering the charge carrier recombination rate. The presented BiZn2VO6 nanocompounds are shown to provide highly competitive performance compared with other state-of-the art photoelectrodes.

    Place, publisher, year, edition, pages
    Cambridge: Royal Society of Chemistry, 2017
    National Category
    Materials Chemistry Condensed Matter Physics Inorganic Chemistry Ceramics
    Identifiers
    urn:nbn:se:liu:diva-134273 (URN)10.1039/C6TA10180A (DOI)000394430800031 ()
    Note

    Funding agencies:  Ministry of Higher Education and Scientific Research, Khartoum-Sudan [700]; Wenner-Gren Foundations; Swedish Government Strategic Research Area in Materials Science on Functional Material at Linkoping University [2009 00971]; Swedish Foundation for Strate

    Available from: 2017-02-02 Created: 2017-02-02 Last updated: 2017-03-31Bibliographically approved
  • 47.
    Erdtman, Edvin
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, Faculty of Science & Engineering.
    Andersson, Mike
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, Faculty of Science & Engineering.
    Lloyd Spetz, Anita
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, Faculty of Science & Engineering.
    Ojamäe, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, Faculty of Science & Engineering.
    Simulations of the thermodynamics and kinetics of NH3 at the RuO2 (110) surface2017In: Surface Science, ISSN 0039-6028, E-ISSN 1879-2758, Vol. 656, 9 p.77-85 p.Article in journal (Refereed)
    Abstract [en]

    •The dehydrogenation of NHless thansubscriptgreater than3less than/subscriptgreater than via a bridging O on RuOless thansubscriptgreater than2less than/subscriptgreater than(110) is rate-determining.•We can confirm the experimental results that water vapour is formed in the sensor.•OH-species are formed on the RuOless thansubscriptgreater than2less than/subscriptgreater than surface which is required for the sensor response.•A multiscale scheme is devised which can be used in a variety of applications.

    The full text will be freely available from 2018-10-20 10:21
  • 48.
    Eriksson, Mats
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Chemical and Optical Sensor Systems. Linköping University, Faculty of Science & Engineering.
    Ekedahl, Lars-Gunnar
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Hydrogen adsorption states at the Pd-SiO2 interface and simulation of the response of a Pd metal-oxide-semiconductor hydrogen sensor1998In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 83, no 8, 3947-3951 p.Article in journal (Refereed)
    Abstract [en]

    The response of a Pd–SiO 2 –Si hydrogen sensor depends on the reaction kinetics of hydrogen on the Pd surface and on the hydrogen adsorption states at the Pd/SiO 2 interface. In this work we show that besides the dominating hydrogen adsorption state located on the oxide side of the interface, a second state, resulting in opposite hydrogen polarization, exists. This state is possibly a reminiscence of the hydrogen adsorption state on a clean Pd surface. Taking both states into account, a simulation of the hydrogen response over more than ten decades in hydrogen pressures gives good agreement with published data.

  • 49.
    Eriksson, Mats
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Chemical and Optical Sensor Systems. Linköping University, Faculty of Science & Engineering.
    Ekedahl, Lars-Gunnar
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Real time measurements of hydrogen desorption and absorption during CO exposures of Pd: Hydrogen sticking and dissolution1998In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 133, no 1-2, 89-97 p.Article in journal (Refereed)
    Abstract [en]

    Combined real time measurements of hydrogen desorption and absorption show that both processes may be induced simultaneously by CO adsorption on a hydrogen-covered Pd surface. The induced absorption is found to be a kinetic effect, where the amount absorbed depends on the hydrogen desorption rate and the CO adsorption rate. In addition to simple site blocking, adsorbed CO induces an increase in the hydrogen desorption energy and an activation barrier for hydrogen dissociation. Both increase linearly with CO coverage for θCO>0.18 ML. Below this coverage, the hydrogen dissociation is non-activated.

  • 50.
    Eriksson, Mats
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Chemical and Optical Sensor Systems. Linköping University, Faculty of Science & Engineering.
    Ekedahl, Lars-Gunnar
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology. Tekniska högskolan.
    The catalytic oxidation of CO on polycrystalline Pd: Experiments and kinetic modelling1998In: Surface Science, ISSN 0039-6028, E-ISSN 1879-2758, Vol. 412/413, 430-440 p.Article in journal (Refereed)
    Abstract [en]

    The catalytic oxidation of CO on a thin, polycrystalline Pd film has been studied. Even though the Pd film is expected to be dominated by (111) facets, some distinct differences compared to single crystalline Pd(111) are observed. A kinetic model for the CO oxidation reaction is presented. It gives good agreement with experiments, both in terms of CO2 reaction probability and CO coverage during reaction conditions. The model assumes a random distribution of the adsorbates, an activation energy for the reaction that decreases with increasing CO coverage, as well as a CO sticking coefficient that in a temperature dependent fashion depends on the oxygen coverage. Single crystal data available from the literature (initial sticking coefficients and heats of adsorption) were mainly used as input parameters. Thus, the model might also be a useful starting point when modeling the catalytic oxidation of CO on single crystal surfaces.

1234 1 - 50 of 160
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • oxford
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf