liu.seSearch for publications in DiVA
Change search
Refine search result
1 - 16 of 16
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)
  • Disputation date (earliest first)
  • Disputation date (latest 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)
  • Disputation date (earliest first)
  • Disputation date (latest 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.
    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, p. 1001-1009Article 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.

  • 2.
    Dini, Francesca
    et al.
    Department of Electronic Engineering, University of Rome, Italy.
    Magna, Gabriele
    Department of Electronic Engineering, University of Rome, Italy.
    Martinelli, Eugenio
    Department of Electronic Engineering, University of Rome, Italy.
    Pomarico, Giuseppe
    Department of Chemical Science and Technologies, University of Rome, Italy.
    Di Natale, Corrado
    Department of Electronic Engineering, University of Rome, Italy.
    Paolesse, Roberto
    Department of Chemical Science and Technologies, University of Rome, Italy.
    Lundström, Ingemar
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, Faculty of Science & Engineering.
    Combining porphyrins and pH indicators for analyte detection2015In: Analytical and Bioanalytical Chemistry, ISSN 1618-2642, E-ISSN 1618-2650, Vol. 407, no 14, p. 3975-3984Article in journal (Refereed)
    Abstract [en]

    High sensitivity and cross-selectivity are mandatory properties for sensor arrays. Although metalloporphyrins and pH indicators are among the most common and appropriate choices for the preparation of optical sensor arrays, the sensitivity spectrum of these dyes is limited to those analytes able to induce an optical response. To extend the receptive field of optical sensors, we explore the design of composite materials, where the molecular interaction among the subunits enriches their sensing working mechanisms. We demonstrate that blends of single metalloporphyrins and pH indicators, tested with a transduction apparatus based on ubiquitous and easily available hardware, can be endowed with sensing properties wider than those of single constituents, enabling the recognition of a broad range of volatiles.

  • 3.
    Dini, Francesca
    et al.
    University of Roma Tor Vergata.
    Martinelli, Eugenio
    University of Roma Tor Vergata.
    Paolesse, Roberto
    University of Roma Tor Vergata.
    Filippini, Daniel
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Schild, Detlev
    University of Gottingen.
    Lundström, Ingemar
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, The Institute of Technology.
    Di Natale, Corrado
    University of Roma Tor Vergata.
    Data processing for image-based chemical sensors: unsupervised region of interest selection and background noise compensation2012In: Analytical and Bioanalytical Chemistry, ISSN 1618-2642, E-ISSN 1618-2650, Vol. 402, no 2, p. 823-832Article in journal (Refereed)
    Abstract [en]

    Natural olfaction suggests that numerous replicas of small sensors can achieve large sensitivity. This concept of sensor redundancy can be exploited by use of optical chemical sensors whose use of image sensors enables the simultaneous measurement of several spatially distributed indicators. Digital image sensors split the framed scene into hundreds of thousands of pixels each corresponding to a portion of the sensing layer. The signal from each pixel can be regarded as an independent sensor, which leads to a highly redundant sensor array. Such redundancy can eventually be exploited to increase the signal-to-noise ratio. In this paper we report an algorithm for reduction of the noise of pixel signals. For this purpose, the algorithm processes the output of groups of pixels whose signals share the same time behavior, as is the case for signals related to the same indicator. To define these groups of pixels, unsupervised clustering, based on classification of the indicator colors, is proposed here. This approach to signal processing is tested in experiments on the chemical sensitivity of replicas of eight indicators spotted on to a plastic substrate. Results show that the groups of pixels can be defined independently of the geometrical arrangement of the sensing spots, and substantial improvement of the signal-to-noise ratio is obtained, enabling the detection of volatile compounds at any location on the distributed sensing layer.

  • 4.
    Fritzsche, Michael
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biotechnology. Linköping University, Faculty of Science & Engineering.
    Mandenius, Carl-Fredrik
    Linköping University, Department of Physics, Chemistry and Biology, Biotechnology. Linköping University, Faculty of Science & Engineering.
    Fluorescent cell-based sensing approaches for toxicity testing2010In: Analytical and Bioanalytical Chemistry, ISSN 1618-2642, E-ISSN 1618-2650, Vol. 398, no 1, p. 181-191Article, review/survey (Refereed)
    Abstract [en]

    Fluorimetric cell-based sensing methods have attracted increasing interest in toxicity testing of pharmaceuticals, pathogens, environmental pollutants, and other chemicals. The objective of this review is to summarise the variety of approaches reported up to now and to present recent developments in this area. The different approaches are described in relation to their underlying mechanism and, especially, to the role of the fluorophore involved. The methods discussed include the use of fluorescent or fluorogenic indicators, fluorescence-based testing for membrane integrity, approaches based on fluorescence labelling, inducible fluorescent protein expression, and analysis of cellular autofluorescence. Several of these approaches have been shown to be advantageous in comparison with non-fluorescence methods and have potential in high-throughput screening, for example in drug discovery and safety pharmacology.

  • 5.
    Gökay, O.
    et al.
    Institute of Organic Chemistry, University of Tübingen, Germany.
    Kühner, D.
    Institute of Microbiology and Infectious Diseases, University of Tübingen, Germany.
    Los, Marek Jan
    Interfaculty Institute for Biochemistry, University of Tübingen, Germany.
    Götz, F.
    Institute of Microbiology and Infectious Diseases, University of Tübingen, Germany.
    Bertsche, U.
    Institute of Microbiology and Infectious Diseases, University of Tübingen, Gemany.
    Albert, K.
    Institute of Organic Chemistry, University of Tübingen, Germany.
    An efficient approach for the isolation, identification and evaluation of antimicrobial plant components on an analytical scale, demonstrated by the example of Radix imperatoriae2010In: Analytical and Bioanalytical Chemistry, ISSN 1618-2642, E-ISSN 1618-2650, Vol. 398, no 5, p. 2039-2047Article in journal (Refereed)
    Abstract [en]

    Using Radix imperatoriae (the root of masterwort) as an example, we describe an efficient approach for the isolation, identification and evaluation of bioactive plant components on an analytical scale. The extraction of Radix imperatoriae with ethyl acetate was enhanced by the application of ultrasound oscillations. This rhizome extract was applied to three pathogenic bacteria ( Bacillus cereus, Escherichia coli, and Staphylococcus aureus) to determine its antimicrobial activity. Disk diffusion was utilized to determine susceptibility. The extract components were separated using a series of chromatography approaches (semi-preparative RP-HPLC, or RP-HPLC on an analytical scale), followed by testing. All fractions were analyzed by LC-UV-ESI-MS and 600 MHz microcoil H NMR spectroscopy. Among other findings, in the fraction with the highest antibacterial activity we were able to identify oxypeucedanin and oxypeucedanin hydrate. Subsequent analysis revealed that only oxypeucedanin hydrate had antibacterial activity, whereas oxypeucedanin itself was inactive at the concentrations applied. Furthermore, oxypeucedanin hydrate appears to be largely, or exclusively, a by-product of sample preparation, since it is either not synthesized by the plant as a second metabolite or is produced by it in only very small quantities.

  • 6.
    Hsu, Ya-Ching
    et al.
    Fooyin University, Taiwan .
    Chen, Bud-Gen
    Fooyin University, Taiwan .
    Yang, Shu-Ching
    National Cheng Kung University, Taiwan .
    Wang, Yu-Shan
    Minist Justice, Taiwan .
    Huang, Shiao-Ping
    Fooyin University, Taiwan .
    Huang, Mei-Han
    Fooyin University, Taiwan .
    Chen, Tai-Jui
    E Da Hospital, Taiwan .
    Liu, Hsu-Chun
    Minist Justice, Taiwan .
    Lin, Dong-Liang
    Minist Justice, Taiwan .
    Liu, Ray H.
    Fooyin University, Taiwan .
    Wayne Jones, A
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medical and Health Sciences, Division of Drug Research.
    Methadone concentrations in blood, plasma, and oral fluid determined by isotope-dilution gas chromatography-mass spectrometry2013In: Analytical and Bioanalytical Chemistry, ISSN 1618-2642, E-ISSN 1618-2650, Vol. 405, no 12, p. 3921-3928Article in journal (Refereed)
    Abstract [en]

    Methadone (MTD) is widely used for detoxification of heroin addicts and also in pain management programs. Information about the distribution of methadone between blood, plasma, and alternative specimens, such as oral fluid (OF), is needed in clinical, forensic, and traffic medicine when analytical results are interpreted. We determined MTD and its metabolite 2-ethylidene-1,5-dimethyl-3,3-diphenylpyrrolidine (EDDP) in blood, plasma, blood cells, and OF by gas chromatography-mass spectrometry (GC-MS) after adding deuterium-labeled internal standards. The analytical limits of quantitation for MTD and EDDP by this method were 20 and 3 ng/mL, respectively. The amounts of MTD and EDDP were higher in plasma (80.4 % and 76.5 %) compared with blood cells (19.6 % and 23.5 %) and we found that repeated washing of blood cells with phosphate-buffered saline increased the amounts in plasma (93.6 % and 88.6 %). Mean plasma/blood concentration ratios of MTD and EDDP in spiked samples (N = 5) were 1.27 and 1.21, respectively. In clinical samples from patients (N = 46), the concentrations of MTD in plasma and whole blood were highly correlated (r = 0.92, p andlt; 0.001) and mean (median) plasma/blood distribution ratios were 1.43 (1.41). The correlations between MTD in OF and plasma (r = 0.46) and OF and blood (r = 0.52) were also statistically significant (p andlt; 0.001) and the mean OF/plasma and OF/blood distribution ratios were 0.55 and 0.77, respectively. The MTD concentration in OF decreased as salivary pH increased (more basic). These results will prove useful in clinical and forensic medicine when MTD concentrations in alternative specimens are compared and contrasted.

  • 7.
    Joda, Hamdi
    et al.
    Universitat Rovira i Virgili, Tarragona, Spain .
    Beni, Valerio
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, The Institute of Technology. Universitat Rovira i Virgili, Tarragona, Spain .
    Alakkulpi, Noora
    Finnish Red Cross Blood Service, Helsinki, Finland .
    Partanen, Jukka
    Finnish Red Cross Blood Service, Helsinki, Finland .
    Lind, Kristina
    TATAA Biocenter AB, Göteborg, Sweden .
    Strömbom, Linda
    TATAA Biocenter AB, Göteborg, Sweden .
    Latta, Daniel
    Institut für Mikrotechnik Mainz GmbH, Germany.
    Höth, Julian
    Institut für Mikrotechnik Mainz GmbH, Germany .
    Katakis, Ioanis
    O´Sullivan, Ciara K.
    Universitat Rovira i Virgili, Tarragona, Spain; Institucio Catalana de Recerca i Estudis Avançats, Barcelona, Spain .
    Medium-high resolution electrochemical genotyping of HLA-DQ2/DQ8 for detection of predisposition to coeliac disease2014In: Analytical and Bioanalytical Chemistry, ISSN 1618-2642, E-ISSN 1618-2650, Vol. 406, no 12, p. 2757-2769Article in journal (Refereed)
    Abstract [en]

    Coeliac disease is a small intestinal disorder, induced by ingestion of gluten in genetically predisposed individuals. Coeliac disease has been strongly linked to human leukocyte antigens (HLA) located on chromosome 6, with almost 100 % of coeliac disease sufferers carrying either a HLA-DQ2 or HLA-DQ8 heterodimer, with the majority carrying HLA-DQ2 encoded by the DQA1*05:01/05:05, DQB1*02:01/02:02 alleles, whereas the remaining carry the HLA-DQ8 encoded by the DQA1*03:01, DQB1*03:02 alleles. In this work, we present the development of a multiplex electrochemical genosensor array of 36 electrodes, housed within a dedicated microfluidic platform and using a total of 10 sequence-specific probes for rapid medium-high resolution HLA-DQ2/DQ8 genotyping. An evaluation of the selectivity of the designed probes was carried out with the target sequences and 44 potentially interfering alleles, including single base mismatch differentiations; good selectivity was demonstrated. The performance of the electrochemical genosensor array was validated, analyzing real human samples for the presence of HLA-DQ2/DQ8 alleles, and compared with those obtained using laboratory-based HLA typing, and an excellent correlation was obtained.

  • 8.
    Joda, Hamdi
    et al.
    Universitat Rovira i Virgili, Spain.
    Beni, Valerio
    Universitat Rovira i Virgili, Spain.
    Curnane, Deidre
    Universitat Rovira i Virgili, Spain.
    Katakis, Ioanis
    Alakulppi, Noora
    Finnish Red Cross Blood Serv, Finland.
    Partanen, Jukka
    Finnish Red Cross Blood Serv, Finland.
    Lind, Kristina
    TATAA Bioctr AB, Sweden.
    Strombom, Linda
    TATAA Bioctr AB, Sweden.
    O´Sullivan, Ciara K.
    Universitat Rovira i Virgili, Spain.
    Low-medium resolution HLA-DQ2/DQ8 typing for coeliac disease predisposition analysis by colorimetric assay2012In: Analytical and Bioanalytical Chemistry, ISSN 1618-2642, E-ISSN 1618-2650, Vol. 403, no 3, p. 807-819Article in journal (Refereed)
    Abstract [en]

    Coeliac disease is an inflammation of the small intestine, occurring in genetically susceptible individuals triggered by the ingestion of gluten. Human Leukocyte Antigens (HLA) DQ2 and DQ8 gene have been identified as key genetic factors in coeliac disease as they are presented in almost 100 % of the patients. These genes are encoded by the combination of certain alleles in the DQA and DQB region of chromosome 6. Specifically, DQA1*05:01 and DQB1*02:01 alleles for serologically defined leukocyte antigen DQ2 cis, DQA1*05:05 and DQB1*02:02 for DQ2 trans and DQA1*03:01 and DQB1*03:02 alleles for the DQ8. Specific identification of these alleles is a challenge due to the high number of alleles that have been identified so far: 46 in the DQA region and 160 in the DQB region (as of IMGT/HLA Database 10/2011 release). In the reported work, the development of a multiplex colorimetric assay for the low to medium HLA typing of the DQ2 and DQ8 genes is presented. The optimisation of probe design and assay conditions, performed by both surface plasmon resonance and enzyme-linked oligonucleotide assay, are reported. Finally, the performances of the developed typing platform were validated by the analysis of real patient samples and HLA typing, compared with those obtained using hospital based typing technology and an excellent correlation obtained.

  • 9.
    Kergoat, Loig
    et al.
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Piro, Benoît
    Université Paris Diderot, France.
    Berggren, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Horowitz, Gilles
    Université Paris Diderot, France.
    Pham, Minh-Chau
    Université Paris Diderot, France.
    Advances in organic transistor-based biosensors: from organic electrochemical transistors to electrolyte-gated organic field-effect transistors.2012In: Analytical and Bioanalytical Chemistry, ISSN 1618-2642, E-ISSN 1618-2650, Vol. 402, no 5, p. 1813-1826Article, review/survey (Refereed)
    Abstract [en]

    Organic electronics have, over the past two decades, developed into an exciting area of research and technology to replace classic inorganic semiconductors. Organic photovoltaics, light-emitting diodes, and thin-film transistors are already well developed and are currently being commercialized for a variety of applications. More recently, organic transistors have found new applications in the field of biosensors. The progress made in this direction is the topic of this review. Various configurations are presented, with their detection principle, and illustrated by examples from the literature.

  • 10.
    Klenkar, Goran
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics . Linköping University, The Institute of Technology.
    Liedberg, Bo
    Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics . Linköping University, The Institute of Technology.
    A Microarray Chip for Label-Free Detection of Narcotics2008In: Analytical and Bioanalytical Chemistry, ISSN 1618-2642, E-ISSN 1618-2650, Vol. 391, no 5, p. 1679-1688Article in journal (Refereed)
    Abstract [en]

    A protein array chip for label-free optical detection of low molecular weight compounds has been developed. As a proof of principle, the chip is proven capable of rapidly (approximately 1 min) determining hits from aqueous cocktails composed of four common narcotics, cocaine, ecstasy, heroin, and amphetamine, using imaging surface plasmon resonance (SPR) as the detection principle. The chip is produced by injecting a mixture of antibodies and letting them self-sort and bind to narcotic analog coupled proteins already present in a predefined pattern on the supporting substrate. An indirect detection method, where antibodies are displaced from the surface upon recognition of their corresponding narcotics, is used to obtain the optical contrast and thus a detectable SPR and/or ellipsometric signal. Two types of readouts are possible from the present setup: intensity SPR images and SPR/ellipsometric sensorgrams. Positive hits were routinely obtained for analyte concentrations of 50 pg/μL and the limit of detection, without any parameter optimizations, seems to fall in the range 0.5 pg/μL (1.4 nM) for heroin, 2.5 pg/μL (8.2 nM) for cocaine, and 5 pg/μL for the other two narcotics (26 nM for ecstasy and 37 nM for amphetamine). With improved readout possibilities (sampling frequency), signal evaluation algorithms, and antibody–antigen design strategies, we believe this limit can be further improved. The chip is shown to work for many measurement cycles with excellent reproducibility. Moreover, with a more advanced fluidic system, excess injected antibodies could be collected and reused for many cycles, which could make the running costs of the system very low. The chip is in no way limited to detection of narcotics. Other low molecular weight compounds could easily be detected on the same chip. For example, trinitrotoluene detection has already been demonstrated using our chip. Possible areas of application for the system are therefore envisaged in airport and underground transport security, customs, drug interdiction, forensics, and as warning alerts on military equipment and personnel.

  • 11.
    Kor, Kamalodin
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, Faculty of Science & Engineering.
    Turner, Anthony
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, Faculty of Science & Engineering.
    Zarei, Kobra
    School of Chemistry, Damghan University, Damghan, Iran.
    Atabati, Morteza
    School of Chemistry, Damghan University, Damghan, Iran.
    Beni, Valerio
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, Faculty of Science & Engineering.
    Mak, Wing Cheung
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, Faculty of Science & Engineering.
    Structurally responsive oligonucleotide-based single-probe lateral-flow test for detection of miRNA-21 mimics2016In: Analytical and Bioanalytical Chemistry, ISSN 1618-2642, E-ISSN 1618-2650, Vol. 408, no 5, p. 1475-1485Article in journal (Refereed)
    Abstract [en]

    A single-probe strip test for the rapid and sensitive detection of miRNA-21 mimics is reported herein. Highly specific structurally responsive bi-functional, thiol and biotin, DNA/LNA oligonucleotide probes (molecular beacons-MB) were designed and conjugated with gold nanoparticles (AuNPs) (i.e. biotin-MB-AuNPs). The proposed design had the ability to modulate the accessibility of the biotin group as a function of the presence of a miRNA target allowing the interaction of the boilable with the streptavidin test zone only in the presence of the miRNA-21 mimics. For quantitative evaluation, images of the strip tests were recorded using a flatbed scanner (Epson Perfection V370 Photo). The colour intensities of the test zones of the strip tests were analysed with the ImageJ software (Scion Corp., USA) and quantified as a function of pixel intensity. The response of the strip test was linear over the range 0.5 to 20 nM miRNA-21 (limit of detection of 115 pM) and showed good reproducibility (intra and inter CVs below 8 %); furthermore, the assay was shown to be highly selective, discriminating other interference miRNAs mimics (e.g. miRNA-221 and miRNA-205). Finally, the proposed strip test was used for detection of miRNA-21 mimics in spiked serum samples, demonstrating its potential for point-of-care clinical applications. Main advantages of the single-probe strip test design are its versatility, simplicity and robustness, which can be easily extended to other miRNA targets by tuning the sequence of the single probe. Furthermore, the use of the structurally responsive single probe is particularly relevant in the case of short-length targets, such as miRNA, whereas a conventional sandwich approach might require a careful control of assay conditions such as hybridization temperature and salt concentration

  • 12.
    Kronstrand, Robert
    et al.
    Linköping University, Department of Medical and Health Sciences, Division of Drug Research. Linköping University, Faculty of Health Sciences. Department of Forensic Genetics and Forensic Toxicology, National Board of Forensic Medicine, Linköping, Sweden.
    Brinkhagen, Linda
    National Board for Forensic Medicine, Linkoping, Sweden .
    Birath-Karlsson, Carolina
    National Board for Forensic Medicine, Linkoping, Sweden .
    Roman, Markus
    National Board for Forensic Medicine, Linkoping, Sweden .
    Josefsson, Martin
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, The Institute of Technology. Department of Forensic Genetics and Forensic Toxicology, National Board of Forensic Medicine, Linköping, Sweden.
    LC-QTOF-MS as a superior strategy to immunoassay for the comprehensive analysis of synthetic cannabinoids in urine2014In: Analytical and Bioanalytical Chemistry, ISSN 1618-2642, E-ISSN 1618-2650, Vol. 406, no 15, p. 3599-3609Article in journal (Refereed)
    Abstract [en]

    The objective of this study was to compare the performance of an immunoassay screening for synthetic cannabinoids with a newly developed confirmation method using liquid chromatography quadrupole time-of-flight mass spectrometry. The screening included metabolites from JWH-018, JWH-073, and AM-2201. The confirmation included metabolites from AM-2201, JWH-018, JWH-019, JWH-073, JWH-081, JWH-122, JWH-210, JWH-250, JWH-398, MAM-2201, RCS-4, and UR-144. The immunoassay was tested and found to have no cross-reactivity with UR-144 metabolites but considerable cross-reactivity with MAM-2201 and JWH-122 metabolites. Sensitivity and specificity for the immunoassay were evaluated with 87 authentic urine samples and found to be 87 % and 82 %, respectively. With a cutoff at 2 ng/ml, the confirmation showed 80 positive findings in 38 cases. The most common finding was JWH-122 5-OH-pentyl, followed by JWH-018 5-OH-pentyl. There were 9 findings of UR-144 metabolites and 3 of JWH-073 metabolites. In summary, the immunoassay performed well, presenting both high sensitivity and specificity for the synthetic cannabinoids present in the urine samples tested. The rapid exchange of one cannabinoid for another may pose problems for immunoassays as well as for confirmation methods. However, we consider time-of-flight mass spectrometry to be superior since new metabolites can be quickly included and identified.

  • 13.
    Nasef, Hany
    et al.
    Universitat Rovira i Virgili, Tarragona, Spain .
    Beni, Valerio
    Universitat Rovira i Virgili, Tarragona, Spain.
    O´Sullivan, Ciara K.
    Universitat Rovira i Virgili, Tarragona, Spain.
    Methylene blue as an electrochemical indicator for DF508 cystic fibrosis mutation detection2010In: Analytical and Bioanalytical Chemistry, ISSN 1618-2642, E-ISSN 1618-2650, Vol. 396, no 4, p. 1423-1432Article in journal (Refereed)
    Abstract [en]

    Cystic fibrosis is one of the most common lifeshortening,childhood-onset inherited diseases. Among the1,000 known cystic fibrosis-related mutations, DF508 is themost common, with a frequency varying between 50% and70% according to geographical areas and populationtypology. In this work, we report the use of methyleneblue as an electrochemical reporting agent in the discriminationof synthetic PCR analogue of the DF508 cysticfibrosis mutation (Mut) from the wild type (Wt). Atoptimum experimental condition, a discrimination factorbetween mutant and wild type of approximately 1.5-foldwas found. The proposed assay was quantitative and linearin the range of 10–100 nM, exhibiting a limit of detectionof 2.64 nM. Electrochemical studies at variable ionicstrength conditions allowed further elucidation of themechanism of the methylene blue (MB)–DNA interaction.To the best of our knowledge, this is the first report ofdetection of hybridisation solely via guanine-specific MB–DNA interaction simultaneously in MB solution, independentof electrostatic interaction as demonstrated in the ionicstrength study. The introduction of formamide in thehybridization buffer, to improve discrimination, was alsoinvestigated. Finally, mutant wild type discrimination wasdemonstrated, at 10 nM concentration, with the use of amulti-sensor setup.

  • 14.
    Nasef, Hany
    et al.
    Universitat Rovira i Virgili, Tarragona, Spain.
    Beni, Valerio
    Universitat Rovira i Virgili, Tarragona, Spain.
    Ozalp, Cengiz
    Universitat Rovira i Virgili, Tarragona, Spain.
    O´Sullivan, Ciara K.
    Universitat Rovira i Virgili, Tarragona, Spain.
    Cystic fibrosis: a label-free detection approach based on thermally modulated electrochemical impedance spectroscopy2010In: Analytical and Bioanalytical Chemistry, ISSN 1618-2642, E-ISSN 1618-2650, Vol. 396, no 7, p. 2565-2574Article in journal (Refereed)
    Abstract [en]

    Cystic fibrosis is one of the most commongenetically inherited diseases in northern Europe, with theDF508 mutation being the most common, and among theCaucasian population being responsible for almost 70% ofcases. In this work, we report on the use of thermallymodulated electrochemical impedance spectroscopy for thediscrimination of the DF508 mutation from the wild-typesequence. DNA probes (15 and 21 bases long) wereimmobilised on the surface of gold electrodes and thevariation of the charge-transfer resistance was monitored asa function of hybridisation. Two sets of targets were used inthis work: synthetic 15-mer sequences and two singlestrandedsynthetic analogues of PCR products 82 (mutant)and 85 (wild type) bases long. Hybridisation with shorttargets resulted in very sequence specific charge-transferresistancevariation with a discrimination factor at roomtemperature between fully complementary and mismatchedsequences of approximately fivefold. However, in the caseof the single-stranded synthetic PCR product analogues, alower discrimination factor was recorded (1.5-fold). Theeffect of temperature was investigated to improve discriminationand the use of a posthybridisation wash at elevatedtemperature resulted in a fivefold improvement in thediscrimination factor. Using an electrode array with probesimmobilised against each of the mutant and wild-typesequences, we achieved an unequivocal detection of theDF508 mutation.

  • 15.
    Roman, Markus
    et al.
    Natl Board Forens Med, Dept Forens Genet and Forens Toxicol, S-58758 Linkoping, Sweden .
    Strom, Lena
    Natl Board Forens Med, Dept Forens Genet and Forens Toxicol, S-58758 Linkoping, Sweden .
    Tell, Helena
    Natl Board Forens Med, Dept Forens Genet and Forens Toxicol, S-58758 Linkoping, Sweden .
    Josefsson, Martin
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology. Linköping, .
    Liquid chromatography/time-of-flight mass spectrometry analysis of postmortem blood samples for targeted toxicological screening2013In: Analytical and Bioanalytical Chemistry, ISSN 1618-2642, E-ISSN 1618-2650, Vol. 405, no 12, p. 4107-4125Article in journal (Refereed)
    Abstract [en]

    A liquid chromatography/time-of-flight mass spectrometry (LC-TOF-MS) method for targeted toxicological screening in human postmortem blood samples from forensic autopsy cases has been developed, validated and compared with a previously used method using gas chromatography with nitrogen-phosphorus detection (GC-NPD). Separation was achieved within 12 min by high-resolution gradient chromatography. Ions were generated in positive and negative electrospray ionization mode and were detected in 2-GHz single mass spectrometry mode, m/z range 50-1,000. Before injection, 0.25 g blood was prepared by protein precipitation with 500 mu L of a mixture of acetonitrile and ethanol containing deuterated internal standards. An in-house database comprising 240 drugs and metabolites was built by analysing solutions from certified standards or other documented reference material available. Identification was based on scoring of retention time, accurate mass measurement and isotopic pattern. Validation was performed on spiked blood samples and authentic postmortem blood samples. The thresholds defined as minimum required performance levels were for most compounds in the range from 0.01 to 0.10 mu g/g. Typically, a mass error of less than 2 ppm and a precision of area measurements of less than 5 % coefficient of variation were achieved. Positive identification was confirmed at concentrations up to 500 mu g/g. Most compounds were determined in positive ionization mode, but for a limited number of compounds (fewer than 4 %) negative ionization was needed and a few early-eluted compounds could not be identified owing to substantial influence of interferences from the matrix and were thus not included in the screening. A robust and valid toxicological screening by LC-TOF-MS for postmortem blood samples, covering 50 % more compounds, and with higher precision and sensitivity than the previously used screening by GC-NPD was achieved.

  • 16.
    Vikingsson, Svante
    et al.
    Linköping University, Department of Medical and Health Sciences, Division of Drug Research. Linköping University, Faculty of Medicine and Health Sciences.
    Dahlberg, Jan-Olof
    Linköping University, Department of Medical and Health Sciences, Division of Drug Research. Linköping University, Faculty of Medicine and Health Sciences.
    Hansson, Johan
    Karolinska University Hospital Solna, Sweden.
    Hoiom, Veronica
    Karolinska University Hospital Solna, Sweden.
    Green, Henrik
    Linköping University, Department of Medical and Health Sciences, Division of Drug Research. Linköping University, Faculty of Medicine and Health Sciences. National Board Forens Med, Department Forens Genet and Forens Toxicol, Artillerigatan 12, S-58758 Linkoping, Sweden.
    Simple and cost-effective liquid chromatography-mass spectrometry method to measure dabrafenib quantitatively and six metabolites semi-quantitatively in human plasma2017In: Analytical and Bioanalytical Chemistry, ISSN 1618-2642, E-ISSN 1618-2650, Vol. 409, no 15, p. 3749-3756Article in journal (Refereed)
    Abstract [en]

    Dabrafenib is an inhibitor of BRAF V600E used for treating metastatic melanoma but a majority of patients experience adverse effects. Methods to measure the levels of dabrafenib and major metabolites during treatment are needed to allow development of individualized dosing strategies to reduce the burden of such adverse events. In this study, an LC-MS/MS method capable of measuring dabrafenib quantitatively and six metabolites semi-quantitatively is presented. The method is fully validated with regard to dabrafenib in human plasma in the range 5-5000 ng/mL. The analytes were separated on a C18 column after protein precipitation and detected in positive electrospray ionization mode using a Xevo TQ triple quadrupole mass spectrometer. As no commercial reference standards are available, the calibration curve of dabrafenib was used for semi-quantification of dabrafenib metabolites. Compared to earlier methods the presented method represents a simpler and more cost-effective approach suitable for clinical studies.

1 - 16 of 16
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