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  • 1.
    Cattelan, Mattia
    et al.
    School of Chemistry, University of Bristol, Cantocks Close, Bristol, United Kingdom.
    Vagin, Mikhail
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, Department of Science and Technology, Laboratory of Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Fox, Neil A.
    School of Chemistry, University of Bristol, Cantocks Close, Bristol, United Kingdom.
    Ivanov, Ivan Gueorguiev
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Shtepliuk, Ivan
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Yakimova, Rositsa
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Anodization study of epitaxial graphene: insights on the oxygen evolution reaction of graphitic materials2019In: Nanotechnology, ISSN 0957-4484, E-ISSN 1361-6528, Vol. 30, no 28, article id 285701Article in journal (Refereed)
    Abstract [en]

    The photoemission electron microscopy and x-ray photoemission spectroscopy were utilized for the study of anodized epitaxial graphene (EG) on silicon carbide as a fundamental aspect of the oxygen evolution reaction on graphitic materials. The high-resolution analysis of surface morphology and composition quantified the material transformation during the anodization. We investigated the surface with lateral resolution amp;lt;150 nm, revealing significant transformations on the EG and the role of multilayer edges in increasing the film capacitance.

  • 2.
    Che, Canyan
    et al.
    Linköping University, Department of Science and Technology. Linköping University, Faculty of Science & Engineering.
    Vagin, Mikhail
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Department of Physics, Chemistry and Biology. Linköping University, Faculty of Science & Engineering.
    Wijeratne, Kosala
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Zhao, Dan
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Warczak, Magdalena
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Jonsson, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Crispin, Xavier
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Conducting Polymer Electrocatalysts for Proton-Coupled Electron Transfer Reactions: Toward Organic Fuel Cells with Forest Fuels2018In: Advanced Sustainable Systems, ISSN 2366-7486, Vol. 317Article in journal (Refereed)
    Abstract [en]

    Lignin is one of the most abundant biopolymers, constituting 25% of plants. The pulp and paper industries extract lignin in their process and today seek new applications for this by-product. Here, it is reported that the aromatic alcohols obtained from lignin depolymerization can be used as fuel in high power density electrical power sources. This study shows that the conducting polymer poly(3,4-ethylenedioxythiophene), fabricated from abundant ele-ments via low temperature synthesis, enables efficient, direct, and reversible chemical-to-electrical energy conversion of aromatic alcohols such as lignin residues in aqueous media. A material operation principle related to the rela-tively high molecular diffusion and ionic conductivity within the conducting polymer matrix, ensuring efficient uptake of protons in the course of proton-coupled electron transfers between organic molecules is proposed.

  • 3.
    Ibupoto, Zafar Hussain
    et al.
    Division of Material Science, Department of Engineering Sciences and Mathematics, Luleå University of Technology, Luleå, Sweden; Dr. M.A Kazi Institute of Chemistry University of Sindh Jamshoro, Sindh, Pakistan.
    Tahira, Aneela
    Division of Material Science, Department of Engineering Sciences and Mathematics, Luleå University of Technology, Luleå, Sweden.
    Tang, PengYi
    Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and BIST, Campus UAB, Bellaterra, Barcelona, Catalonia, Spain; Catalonia Institute for Energy Research (IREC), Jardins de les Dones de Negre 1, Sant Adrià del Besòs, Barcelona, Catalonia, Spain.
    Liu, Xianjie
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Morante, Joan Ramon
    Catalonia Institute for Energy Research (IREC), Jardins de les Dones de Negre 1, Sant Adrià del Besòs, Barcelona, Catalonia, Spain.
    Fahlman, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Arbiol, Jordi
    Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and BIST, Campus UAB, Bellaterra, Barcelona, Catalonia, Spain; ICREA, Pg. Lluís Companys 23, Barcelona, Catalonia, Spain.
    Vagin, Mikhail
    Linköping University, Department of Science and Technology, Laboratory of Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Vomiero, Alberto
    Division of Material Science, Department of Engineering Sciences and Mathematics, Luleå University of Technology, Luleå, Sweden.
    MoSx@NiO Composite Nanostructures: An Advanced Nonprecious Catalyst for Hydrogen Evolution Reaction in Alkaline Media2019In: Advanced Functional Materials, ISSN 1616-301X, E-ISSN 1616-3028, Vol. 29, no 7, article id 1807562Article in journal (Refereed)
    Abstract [en]

    The design of the earth-abundant, nonprecious, efficient, and stable electrocatalysts for efficient hydrogen evolution reaction (HER) in alkaline media is a hot research topic in the field of renewable energies. A heterostructured system composed of MoSx deposited on NiO nanostructures (MoSx@NiO) as a robust catalyst for water splitting is proposed here. NiO nanosponges are applied as cocatalyst for MoS2 in alkaline media. Both NiO and MoS2@NiO composites are prepared by a hydrothermal method. The NiO nanostructures exhibit sponge-like morphology and are completely covered by the sheet-like MoS2. The NiO and MoS2 exhibit cubic and hexagonal phases, respectively. In the MoSx@NiO composite, the HER experiment in 1 m KOH electrolyte results in a low overpotential (406 mV) to produce 10 mA cm(-2) current density. The Tafel slope for that case is 43 mV per decade, which is the lowest ever achieved for MoS2-based electrocatalyst in alkaline media. The catalyst is highly stable for at least 13 h, with no decrease in the current density. This simple, cost-effective, and environmentally friendly methodology can pave the way for exploitation of MoSx@NiO composite catalysts not only for water splitting, but also for other applications such as lithium ion batteries, and fuel cells.

    The full text will be freely available from 2020-01-02 12:00
  • 4.
    Imar, Shahzad
    et al.
    Dundalk Institute Technology, Ireland.
    Maccato, Chiara
    University of Padua, Italy.
    Dickinson, Calum
    University of Limerick, Ireland.
    Laffir, Fathima
    University of Limerick, Ireland.
    Vagin, Mikhail
    Linköping University, Department of Physics, Chemistry and Biology, Chemical and Optical Sensor Systems. Linköping University, The Institute of Technology.
    McCormac, Timothy
    Dundalk Institute Technology, Ireland.
    Enhancement of Nitrite and Nitrate Electrocatalytic Reduction through the Employment of Self-Assembled Layers of Nickel- and Copper-Substituted Crown-Type Heteropolyanions2015In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 31, no 8, p. 2584-2592Article in journal (Refereed)
    Abstract [en]

    Multilayer assemblies of two crown-type type heteropolyanions (HPA), [Cu20Cl(OH)(24)(H2O)(12)(P8W48O184)](25-) and Ni-4(P8W48O148)(WO2)](28-), have been immobilized onto glassy carbon electrode surfaces via the layer-by-layer (LBL) technique employing polycathion-stabilized silver nanoparticles (AgNP) as the cationic layer within the resulting thin films characterized by electrochemical and physical methods. The redox behaviors of both HPA monitored during LBL assembly with cyclic voltammetry and impedance spectroscopy revealed significant changes by immobilization. The presence of AgNPs led to the retention of film porosity and electronic conductivity, which has been shown with impedance and voltammeric studies of film permeabilities toward reversible redox probes. The resulting films have been characterized by physical methods. Finally, the electrocatalytic performance of obtained films with respect to nitrite and nitrate electrocatalytic reduction has been comparatively studied for both catalysts. Nickel atoms trapped inside HPA exhibited a higher specific activity for reduction.

  • 5.
    Imar, Shahzad
    et al.
    Dundalk Institute Technology, Ireland.
    Yaqub, Mustansara
    Dundalk Institute Technology, Ireland.
    Maccato, Chiara
    University of Padua, Italy.
    Dickinson, Calum
    University of Limerick, Ireland.
    Laffir, Fathima
    University of Limerick, Ireland.
    Vagin, Mikhail
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    McCormac, Timothy
    Dundalk Institute Technology, Ireland.
    Nitrate and Nitrite Electrocatalytic Reduction at Layer-by-Layer Films Composed of Dawson-type Heteropolyanions Mono-substituted with Transitional Metal Ions and Silver Nanoparticles2015In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 184, p. 323-330Article in journal (Refereed)
    Abstract [en]

    A series of Dawson-type heteropolyanions (HPAs) mono-substituted with transitional metal ions ((alpha 2)- [P2W17O61FeIII](8-), (alpha 2)-[P2W17O61CuII](8-) and (alpha 2)-[P2W17O61NiII](8-)) have exhibited electrocatalytic properties towards nitrate and nitrite reduction in slightly acidic media (pH 4.5). The immobilization of these HPAs into water-processable films developed via layer-by layer assembly with polymer-stabilized silver nanoparticles led to the fabrication of the electrocatalytic interfaces for both nitrate and nitrite reduction. The LBL assembly as well as the changes in the HPA properties by immobilization has been characterized by electrochemical methods. The effects of the substituent ions, outer layers and the cationic moieties utilized for the films assembly of the developed film on the performances of nitrate electrocatalysis has been elucidated. (C) 2015 Elsevier Ltd. All rights reserved.

  • 6.
    Karimian, Najmeh
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, The Institute of Technology. Ferdowsi University of Mashhad, Iran.
    Vagin, Mikhail
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Hossein Arbab Zavar, Mohammad
    Ferdowsi University of Mashhad, Iran .
    Chamsaz, Mahmoud
    Ferdowsi University of Mashhad, Iran .
    Turner, Anthony
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, The Institute of Technology.
    Tiwari, Ashutosh
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, The Institute of Technology.
    An ultrasensitive molecularly-imprinted human cardiac troponin sensor2013In: Biosensors & bioelectronics, ISSN 0956-5663, E-ISSN 1873-4235, Vol. 50, p. 492-498Article in journal (Refereed)
    Abstract [en]

    Cardiac troponin T (TnT) is a highly sensitive cardiac biomarker for myocardial infarction. In this study, the fabrication and characterisation of a novel sensor for human TnT based on a molecularly-imprinted electrosynthesised polymer is reported. A TnT sensitive layer was prepared by electropolymerisation of o-phenylenediamine (o-PD) on a gold electrode in the presence of TnT as a template. To develop the molecularly imprinted polymer (MIP), the template molecules were removed from the modified electrode surface by washing with alkaline ethanol. Electrochemical methods were used to monitor the processes of electropolymerisation, template removal and binding. The imprinted layer was characterised by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and atomic force microscopy (AFM). The incubation of the MIP-modified electrode with respect to TnT concentration resulted in a suppression of the ferro/ferricyanide redox process. Experimental conditions were optimised and a linear relationship was observed between the peak current of [Fe(CN)(6)](3-)/[Fe (CN)(6)](4-) and the concentration of TnT in buffer over the range 0.009-0.8 ng/mL, with a detection limit of 9 pg/mL. The TnT MIP sensor was shown to have a high affinity to TnT in comparison with nonimprinted polymer (NIP) electrodes in both buffer and blood serum.

  • 7.
    Naseer, Rashda
    et al.
    Dundalk Institute Technology, Ireland .
    Sankar Mal, Sib
    Jacobs University, Bremen, Germany .
    Ibrahim, Masooma
    Jacobs University, Bremen, Germany .
    Kortz, Ulrich
    Jacobs University, Bremen, Germany .
    Armstrong, Gordon
    University of Limerick, Ireland .
    Laffir, Fathima
    University of Limerick, Ireland .
    Dickinson, Calum
    University of Limerick, Ireland .
    Vagin, Mikhail
    Linköping University, Department of Physics, Chemistry and Biology, Chemical and Optical Sensor Systems. Linköping University, The Institute of Technology.
    McCormac, Timothy
    Dundalk Institute Technology, Ireland .
    Redox, surface and electrocatalytic properties of layer-by-layer films based upon Fe(III)-substituted crown polyoxometalate [P8W48O184Fe16(OH)(28)(H2O)(4)](20-)2014In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 134, p. 450-458Article in journal (Refereed)
    Abstract [en]

    The electrocatalytic ability of the iron-substituted crown-type polyoxometalate (POM) Li4K16[P8W48O184Fe16(OH)(28)(H2O)(4)]center dot 66H(2)O center dot 2KCl (P8W48Fe16) towards the reduction of both nitrite and hydrogen peroxide reduction has been studied in both the solution and immobilized states for the POM. P8W48Fe16 was surface immobilised onto carbon electrode surfaces through employment of the layer-by-layer technique (LBL) using pentaerythritol-based Ru(II)-metallodendrimer [RuD](PF6)(8) as the cationic layer within the resulting films. The constructed multilayer films have been extensively studied by various electrochemical techniques and surface based techniques. Cyclic voltammetry and impedance spectroscopy have been utilized to monitor the construction of the LBL film after the deposition of each monolayer. The electrochemical behaviour of both a cationic and anionic redox probes at the LBL films has been undertaken to give indications as to the films porosity. The elemental composition and the surface morphology of the LBL films was conifmrde through the employment of AFM, XPS and SEM.

  • 8.
    Naseer, Rashda
    et al.
    Dundalk Institute Technology, Ireland.
    Sankar Mal, Sib
    Jacobs University of Bremen, Germany.
    Kortz, Ulrich
    Jacobs University of Bremen, Germany.
    Armstrong, Gordon
    University of Limerick, Ireland.
    Laffir, Fathima
    University of Limerick, Ireland.
    Dickinson, Calum
    University of Limerick, Ireland.
    Vagin, Mikhail
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    McCormac, Timothy
    Dundalk Institute Technology, Ireland.
    Electrocatalysis by crown-type polyoxometalates multi-substituted by transition metal ions: Comparative study2015In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 176, p. 1248-1255Article in journal (Refereed)
    Abstract [en]

    The difference in electrochemical properties of three crown-type polyoxometalates multi-substituted by Fe3+, Ni2+ or Co2+ ions and their precursor has been rationalized with respect to their electrocatalytic performances studied in solution and in the immobilized state within the layer-by-layer film formed with a positively charged pentaerythritol-based Ru(II)-metallodendrimer. The film assembly was monitored with electrochemical methods and characterized by surface analysis techniques. An influence of the terminal layer on the electrode reaction and on film porosity has been observed. The electrocatalytic performance of the compounds on nitrite reduction was assessed in solution and in the immobilized state. (C) 2015 Elsevier Ltd. All rights reserved.

  • 9.
    Pozhitkov, Alex E.
    et al.
    University of Washington, WA 98195 USA.
    Daubert, Diane
    University of Washington, WA 98195 USA.
    Brochwicz Donimirski, Ashley
    University of Washington, WA 98195 USA.
    Goodgion, Douglas
    University of Washington, WA 98195 USA.
    Vagin, Mikhail
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Leroux, Brian G.
    University of Washington, WA 98195 USA.
    Hunter, Colby M.
    Alabama State University, AL 36101 USA.
    Flemmig, Thomas F.
    University of Hong Kong, Peoples R China.
    Noble, Peter A.
    Alabama State University, AL 36101 USA.
    Bryers, James D.
    University of Washington, WA 98195 USA.
    Interruption of Electrical Conductivity of Titanium Dental Implants Suggests a Path Towards Elimination Of Corrosion2015In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 10, no 10, p. e0140393-Article in journal (Refereed)
    Abstract [en]

    Peri-implantitis is an inflammatory disease that results in the destruction of soft tissue and bone around the implant. Titanium implant corrosion has been attributed to the implant failure and cytotoxic effects to the alveolar bone. We have documented the extent of titanium release into surrounding plaque in patients with and without peri-implantitis. An in vitro model was designed to represent the actual environment of an implant in a patients mouth. The model uses actual oral microbiota from a volunteer, allows monitoring electrochemical processes generated by biofilms growing on implants and permits control of biocorrosion electrical current. As determined by next generation DNA sequencing, microbial compositions in experiments with the in vitro model were comparable with the compositions found in patients with implants. It was determined that the electrical conductivity of titanium implants was the key factor responsible for the biocorrosion process. The interruption of the biocorrosion current resulted in a 4-5 fold reduction of corrosion. We propose a new design of dental implant that combines titanium in zero oxidation state for osseointegration and strength, interlaid with a nonconductive ceramic. In addition, we propose electrotherapy for manipulation of microbial biofilms and to induce bone healing in peri-implantitis patients.

  • 10.
    Qian, Deping
    et al.
    Linköping University, Faculty of Science & Engineering. Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics.
    Liu, Bo
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Wang, Suhao
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Himmelberger, Scott
    Stanford University, CA 94305 USA.
    Linares, Mathieu
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Chemistry. Linköping University, Faculty of Science & Engineering.
    Vagin, Mikhail
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Muller, Christian
    Chalmers, Sweden.
    Zaifei, Zaifei
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Fabiano, Simone
    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.
    Salleo, Alberto
    Stanford University, CA 94305 USA.
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Zou, Yingping
    Central S University, Peoples R China.
    Zhang, Fengling
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Modulating molecular aggregation by facile heteroatom substitution of diketopyrrolopyrrole based small molecules for efficient organic solar cells2015In: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 3, no 48, p. 24349-24357Article in journal (Refereed)
    Abstract [en]

    In conjugated polymers and small molecules of organic solar cells, aggregation induced by intermolecular interactions governs the performance of photovoltaics. However, little attention has been paid to the connection between molecular structure and aggregation within solar cells based on soluble small molecules. Here we demonstrate modulation of intermolecular aggregation of two synthesized molecules through heteroatom substitution to develop an understanding of the role of aggregation in conjugated molecules. Molecule 1 (M1) based on 2-ethylhexyloxy-benzene substituted benzo[1,2-b:4,5-b]dithiophene (BDTP) and diketopyrrolopyrrole (DPP) displays strong aggregation in commonly used organic solvents, which is reduced in molecule 2 (M2) by facile oxygen atom substitution on the BDTP unit confirmed by absorption spectroscopy and optical microscopy, while it successfully maintains molecular planarity and favorable charge transport characteristics. Solar cells based on M2 exhibit more than double the photocurrent of devices based on M1 and yield a power conversion efficiency of 5.5%. A systematic investigation of molecular conformation, optoelectronic properties, molecular packing and crystallinity as well as film morphology reveals structure dependent aggregation responsible for the performance difference between the two conjugated molecules.

  • 11.
    Santangelo, Francesca
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Sensor and Actuator Systems. Linköping University, Faculty of Science & Engineering.
    Shtepliuk, Ivan
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Filippini, Daniel
    Linköping University, Department of Physics, Chemistry and Biology, Sensor and Actuator Systems. Linköping University, Faculty of Science & Engineering.
    Puglisi, Donatella
    Linköping University, Department of Physics, Chemistry and Biology, Sensor and Actuator Systems. Linköping University, Faculty of Science & Engineering.
    Vagin, Mikhail
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Yakimova, Rositsa
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Eriksson, Jens
    Linköping University, Department of Physics, Chemistry and Biology, Sensor and Actuator Systems. Linköping University, Faculty of Science & Engineering.
    Epitaxial Graphene Sensors Combined with 3D-Printed Microfluidic Chip for Heavy Metals Detection2019In: Sensors, ISSN 1424-8220, E-ISSN 1424-8220, Vol. 19, no 10, article id 2393Article in journal (Refereed)
    Abstract [en]

    In this work, we investigated the sensing performance of epitaxial graphene on Si-face 4H-SiC (EG/SiC) for liquid-phase detection of heavy metals (e.g., Pb and Cd), showing fast and stable response and low detection limit. The sensing platform proposed includes 3D-printed microfluidic devices, which incorporate all features required to connect and execute lab-on-chip (LOC) functions. The obtained results indicate that EG exhibits excellent sensing activity towards Pb and Cd ions. Several concentrations of Pb2+ solutions, ranging from 125 nM to 500 mu M, were analyzed showing Langmuir correlation between signal and Pb2+ concentrations, good stability, and reproducibility over time. Upon the simultaneous presence of both metals, sensor response is dominated by Pb2+ rather than Cd2+ ions. To explain the sensing mechanisms and difference in adsorption behavior of Pb2+ and Cd2+ ions on EG in water-based solutions, we performed van-der-Waals (vdW)-corrected density functional theory (DFT) calculations and non-covalent interaction (NCI) analysis, extended charge decomposition analysis (ECDA), and topological analysis. We demonstrated that Pb2+ and Cd2+ ions act as electron-acceptors, enhancing hole conductivity of EG, due to charge transfer from graphene to metal ions, and Pb2+ ions have preferential ability to binding with graphene over cadmium. Electrochemical measurements confirmed the conductometric results, which additionally indicate that EG is more sensitive to lead than to cadmium.

  • 12.
    Sekretareva, Alina
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Chemical and Optical Sensor Systems. Linköping University, Faculty of Science & Engineering.
    Vagin, Mikhail
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Volkov, Anton V.
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Zozoulenko, Igor V.
    Linköping University, Department of Science and Technology, Physics and Electronics. 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.
    Eriksson, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Chemical and Optical Sensor Systems. Linköping University, Faculty of Science & Engineering.
    Screen printed microband array based biosensor for water monitoring2015In: The Frumkin Symposium, 2015Conference paper (Refereed)
  • 13.
    Sekretareva, Alina
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Chemical and Optical Sensor Systems. Linköping University, Faculty of Science & Engineering.
    Vagin, Mikhail Yu
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Volkov, Anton V.
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Zozoulenko, Igor V.
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Turner, Anthony P.F.
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, Faculty of Science & Engineering.
    Eriksson, Mats.
    Linköping University, Department of Physics, Chemistry and Biology, Chemical and Optical Sensor Systems. Linköping University, Faculty of Science & Engineering.
    Total phenol analysis of water using a laccase-based microsensor array2015In: Program of the XXIII International Symposium on Bioelectrochemistry and Bioenergetics of the Bioelectrochemical Society. 14-18 June, 2015. Malmö, Sweden, Lausanne: Bioelectrochemical Society , 2015, p. 155-155Conference paper (Other academic)
    Abstract [en]

    The monitoring of phenolic compounds in raw waters and wastewaters is of great importance for environmental control. Use of biosensors for rapid, specific and simple detection of phenolic compounds is a promising approach. A number of biosensors have been developed for phenol detection. A general drawback of previously reported biosensors is their insufficient detection limits for phenols in water samples. One way to improve the detection limit is by the use of microelectrodes.

    Microband design of the microelectrodes combines convergent mass transport due to the microscale width and high output currents due to the macroscopic length. Among the various techniques available for microband electrode fabrication, we have chosen screen-printing which is a cost-effective production method.

    In this study, we report on the development of a laccase-based microscale biosensor operating under a convergent diffusion regime. Screen-printing followed by simple cutting was utilized for the fabrication of graphite microbands as a platform for further covalent immobilization of laccase. Numerical simulations, utilizing the finite element method with periodic boundary conditions, were used for modeling the voltammetric response of the developed microband electrodes. Anodization followed by covalent immobilization was used for the electrode modification with laccase. Direct and mediated laccase bioelectrocatalytic oxidation of phenols was studied on macro- and microscale graphite electrodes. Significant enhancement of the analytical performance was achieved by the establishment of convergent diffusion in the microscale sensor. Finally, the developed microsensor was utilized to monitor phenolic compounds in real waste water.

  • 14.
    Sekretaryova, Alina
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Chemical and Optical Sensor Systems. Linköping University, The Institute of Technology.
    Beni, Valerio
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, The Institute of Technology.
    Eriksson, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Chemical and Optical Sensor Systems. Linköping University, The Institute of Technology.
    Karyakin, Arkady A.
    Moscow MV Lomonosov State University, Russia.
    Turner, Anthony
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, The Institute of Technology.
    Vagin, Mikhail
    Linköping University, Department of Physics, Chemistry and Biology, Chemical and Optical Sensor Systems. Linköping University, The Institute of Technology.
    Cholesterol Self-Powered Biosensor2014In: Analytical Chemistry, ISSN 0003-2700, E-ISSN 1520-6882, Vol. 86, no 19, p. 9540-9547Article in journal (Refereed)
    Abstract [en]

    Monitoring the cholesterol level is of great importance, especially for people with high risk of developing heart disease. Here we report on reagentless cholesterol detection in human plasma with a novel single-enzyme, membrane-free, self-powered biosensor, in which both cathodic and anodic bioelectrocatalytic reactions are powered by the same substrate. Cholesterol oxidase was immobilized in a sol-gel matrix on both the cathode and the anode. Hydrogen peroxide, a product of the enzymatic conversion of cholesterol, was electrocatalytically reduced, by the use of Prussian blue, at the cathode. In parallel, cholesterol oxidation catalyzed by mediated cholesterol oxidase occurred at the anode. The analytical performance was assessed for both electrode systems separately. The combination of the two electrodes, formed on high surface-area carbon cloth electrodes, resulted in a self-powered biosensor with enhanced sensitivity (26.0 mA M-1 cm(-2)), compared to either of the two individual electrodes, and a dynamic range up to 4.1 mM cholesterol. Reagentless cholesterol detection with both electrochemical systems and with the self-powered biosensor was performed and the results were compared with the standard method of colorimetric cholesterol quantification.

  • 15.
    Sekretaryova, Alina
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, The Institute of Technology.
    Beni, Valerio
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, The Institute of Technology.
    Eriksson, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Chemical and Optical Sensor Systems. Linköping University, The Institute of Technology.
    Turner, Anthony
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, The Institute of Technology.
    Vagin, Mikhail Y
    Linköping University, Department of Physics, Chemistry and Biology, Chemical and Optical Sensor Systems. Linköping University, The Institute of Technology.
    A highly sensitive and self-powered cholesterol biosensor2014In: 24th Anniversary World Congress on Biosensors – Biosensors 2014, Elsevier, 2014Conference paper (Other academic)
    Abstract [en]

    Blood cholesterol is a very important parameter for the assessment of atherosclerosis and other lipid disorders. The total cholesterol concentration in human blood should be less than 5.17 mM. Concentrations in the range 5.17 – 6.18 mM are considered borderline high risk and levels above 6.21 mM, high risk. Cholesterol determination with high accuracy is therefore necessary in order to differentiate these levels for medical screening or diagnosis. Several attempts to develop highly sensitive cholesterol biosensors have been described, but, to the best of our knowledge, this is the first report of a self-powered cholesterol biosensor, i.e. a device delivering the analytical information from the current output of the energy of the biocatalytic conversion of cholesterol, without any external power source. This is particularly relevant to the development of inexpensive screening devices based on printed electronics.

     

    We present two complementary bioelectrocatalytic platforms suitable for the fabrication of a self-powered biosensor. Both are based on cholesterol oxidase (ChOx) immobilisation in a sol-gel matrix, as illustrated in Fig. 1 [1]. Mediated biocatalytic cholesterol oxidation [2] was used as the anodic reaction and electrocatalytic reduction of hydrogen peroxide on Prussian Blue (PB) as the cathodic reaction. Due to a synergistic effect in the self-powered cholesterol biosensor, the analytical parameters of the overall device exceeded those of the individual component half-cells, yielding a sensitivity of 0.19 A M-1 cm-2 and a dynamic range that embraces the free cholesterol concentrations found in human blood.

     

    Thus, we have demonstrated the novel concept of highly sensitive cholesterol determination using the first self-powered cholesterol biosensor. This configuration is particularly promising for incorporation in emerging plastic- and paper-based analytical instruments for decentralised diagnostics and mobile health.

     

  • 16.
    Sekretaryova, Alina N
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, The Institute of Technology.
    Beni, Valerio
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, The Institute of Technology.
    Eriksson, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Chemical and Optical Sensor Systems. Linköping University, The Institute of Technology.
    Karyakin, Arkady A
    Moscow State University, Russia.
    Turner, Anthony
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, The Institute of Technology.
    Vagin, Mikhail Y
    Linköping University, Department of Physics, Chemistry and Biology, Chemical and Optical Sensor Systems. Linköping University, The Institute of Technology.
    Novel single-enzyme based self-powered biosensor2014In: 15th International Conference on Electroanalysis (ESEAC), 2014Conference paper (Other academic)
  • 17.
    Sekretaryova, Alina N
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, The Institute of Technology.
    Vagin, Mikhail Y
    Linköping University, Department of Physics, Chemistry and Biology, Chemical and Optical Sensor Systems. Linköping University, The Institute of Technology.
    Turner, Anthony
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, The Institute of Technology.
    Eriksson, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Chemical and Optical Sensor Systems. Linköping University, The Institute of Technology.
    A screen-printed microband array biosensor for water monitoring2014In: 15th International Conference on Electroanalysis (ESEAC), 2014Conference paper (Other academic)
  • 18.
    Sekretaryova, Alina N.
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Chemical and Optical Sensor Systems. Linköping University, Faculty of Science & Engineering.
    Vagin, Mikhail Yu.
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Eriksson, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Chemical and Optical Sensor Systems. Linköping University, Faculty of Science & Engineering.
    Evaluation of the electrochemically active surface area of microelectrodes by capacitive and faradaic currentsManuscript (preprint) (Other academic)
    Abstract [en]

    Two methods to estimate the electrochemically active surface area (EASA) of microelectrodes were compared. One is based on electrocapacitive measurements and the other on faradaic measuements. A systematic study revealed a strong influence of the surface roughness and the electrolyte concentration on the EASA of microelectrodes estimated from the electrocapacitive measurements, yielding a lack of reliability compared to the faradaic method.

  • 19.
    Sekretaryova, Alina N.
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Chemical and Optical Sensor Systems. Linköping University, Faculty of Science & Engineering.
    Vagin, Mikhail Yu.
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Turner, Anthony P.F.
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, Faculty of Science & Engineering.
    Eriksson, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Chemical and Optical Sensor Systems. Linköping University, Faculty of Science & Engineering.
    Electrocatalytic Currents from Single Enzyme Molecules2016In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 138, no 8, p. 2504-2507Article in journal (Refereed)
    Abstract [en]

    Single molecule enzymology provides an opportunity to examine details of enzyme mechanisms that are not distinguishable in biomolecule ensemble studies. Here we report, for the first time, detection of the current produced in an electrocatalytic reaction by a single redox enzyme molecule when it collides with an ultramicroelectrode. The catalytic process provides amplification of the current from electron-transfer events at the catalyst leading to a measurable current. This new methodology monitors turnover of a single enzyme molecule. The methodology might complement existing single molecule techniques, giving further insights into enzymatic mechanisms and filling the gap between fundamental understanding of biocatalytic processes and their potential for bioenergy production.

  • 20.
    Sekretaryova, Alina
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, The Institute of Technology.
    Vagin, Mikhail
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Beni, Valerio
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, The Institute of Technology.
    Eriksson, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Turner, Anthony
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, The Institute of Technology.
    Unsubstitutedand insoluble phenothiazine as an electron-transfer mediator in enzymaticelectrochemical biosensors2013In: Nano-scaled arrangements of proteins, aptamers, andother nucleic acid structures – and their potential applications , COST Thematic Workshop, 8-9 October 2013, Helmholtz Zentrum fürUmweltforschung, Leipzig, Germany, Leipzig: Helmholtz Zentrum für Umweltforschung , 2013, p. O1-Conference paper (Refereed)
  • 21.
    Sekretaryova, Alina
    et al.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology. Lomonosov Moscow State University, Russia.
    Vagin, Mikhail
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Beni, Valerio
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, The Institute of Technology.
    Turner, Anthony P.F.
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, The Institute of Technology.
    Karyakin, Arkady A.
    Lomonosov Moscow State University, Russia.
    Unsubstituted phenothiazine as a superior water-insoluble mediator for oxidases2014In: Biosensors & bioelectronics, ISSN 0956-5663, E-ISSN 1873-4235, Vol. 53, p. 275-282Article in journal (Refereed)
    Abstract [en]

    The mediation of oxidases glucose oxidase (GOx), lactate oxidase (LOx) and cholesterol oxidase (ChOx) by a new electron shuttling mediator, unsubstituted phenothiazine (PTZ), was studied. Cyclic voltammetry and rotating-disk electrode measurements in nonaqueous media were used to determine the diffusion characteristics of the mediator and the kinetics of its reaction with GOx, giving a second-order rate constant of 7.6×103–2.1×104 M−1 s−1 for water–acetonitrile solutions containing 5–15% water. These values are in the range reported for commonly used azine-type mediators, indicating that PTZ is able to function as an efficient mediator. PTZ and GOx, LOx and ChOx were successfully co-immobilised in sol–gel membrane on a screen-printed electrode to construct glucose, lactate and cholesterol biosensors, respectively, which were then optimised in terms of stability and sensitivity. The electrocatalytic oxidation responses showed a dependence on substrate concentration ranging from 0.6 to 32 mM for glucose, from 19 to 565 mM for lactate and from 0.015 to 1.0 mM for cholesterol detection. Oxidation of substrates on the surface of electrodes modified with PTZ and enzyme membrane was investigated with double-step chronoamperometry and the results showed that the PTZ displays excellent electrochemical catalytic activities even when immobilised on the surface of the electrode.

  • 22.
    Sekretaryova, Alina
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Chemical and Optical Sensor Systems. Linköping University, Faculty of Science & Engineering.
    Volkov, Anton V.
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Zozoulenko, Igor V.
    Linköping University, Department of Science and Technology, Physics and Electronics. 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.
    Vagin, Mikhail Yu
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Eriksson, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Chemical and Optical Sensor Systems. Linköping University, Faculty of Science & Engineering.
    Total phenol analysis of weakly supported water using a laccase-based microband biosensor.2016In: Analytica Chimica Acta, ISSN 0003-2670, E-ISSN 1873-4324, Vol. 907, p. 45-53Article in journal (Refereed)
    Abstract [en]

    The monitoring of phenolic compounds in wastewaters in a simple manner is of great importance for environmental control. Here, a novel screen printed laccase-based microband array for in situ, total phenol estimation in wastewaters and for water quality monitoring without additional sample pre-treatment is presented. Numerical simulations using the finite element method were utilized for the characterization of micro-scale graphite electrodes. Anodization followed by covalent modification was used for the electrode functionalization with laccase. The functionalization efficiency and the electrochemical performance in direct and catechol-mediated oxygen reduction were studied at the microband laccase electrodes and compared with macro-scale electrode structures. The reduction of the dimensions of the enzyme biosensor, when used under optimized conditions, led to a significant improvement in its analytical characteristics. The elaborated microsensor showed fast responses towards catechol additions to tap water – a weakly supported medium – characterized by a linear range from 0.2 to 10 μM, a sensitivity of 1.35 ± 0.4 A M−1 cm−2 and a dynamic range up to 43 μM. This enhanced laccase-based microsensor was used for water quality monitoring and its performance for total phenol analysis of wastewater samples from different stages of the cleaning process was compared to a standard method.

  • 23.
    Shtepliuk, Ivan I.
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering. NASU, Ukraine.
    Vagin, Mikhail
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Ivanov, Ivan Gueorguiev
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Iakimov, Tihomir
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Yazdi, Gholamreza
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Yakimova, Rositsa
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Lead (Pb) interfacing with epitaxial graphene2018In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 20, no 25, p. 17105-17116Article in journal (Refereed)
    Abstract [en]

    Here, we report the electrochemical deposition of lead (Pb) as a model metal on epitaxial graphene fabricated on silicon carbide (Gr/SiC). The kinetics of electrodeposition and morphological characteristics of the deposits were evaluated by complementary electrochemical, physical and computational methods. The use of Gr/SiC as an electrode allowed the tracking of lead-associated redox conversions. The analysis of current transients passed during the deposition revealed an instantaneous nucleation mechanism controlled by convergent mass transport on the nuclei locally randomly distributed on epitaxial graphene. This key observation of the deposit topology was confirmed by low values of the experimentally-estimated apparent diffusion coefficient, Raman spectroscopy and scanning electron microscopy (SEM) studies. First principles calculations showed that the nucleation of Pb clusters on the graphene surface leads to weakening of the interaction strength of the metal-graphene complex, and only spatially separated Pb adatoms adsorbed on bridge and/or edge-plane sites can affect the vibrational properties of graphene. We expect that the lead adatoms can merge in large metallic clusters only at defect sites that reinforce the metal-graphene interactions. Our findings provide valuable insights into both heavy metal ion electrochemical analysis and metal electroplating on graphene interfaces that are important for designing effective detectors of toxic heavy metals.

  • 24.
    Turner, Anthony
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, The Institute of Technology.
    Karimian, Najmeh
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, The Institute of Technology. Ferdowsi University of Mashhad, Iran.
    Tiwari, Ashutosh
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, The Institute of Technology.
    Vagin, Mikhail
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Zavar, M. H. A.
    Chamsaz, M.
    Zohuri, G.
    Amperometric cardiac troponin affinity sensor based on electrochemically synthesised troponin imprinted polymer over a Au electrode2013In: 19th Iranian Seminar on Analytical Chemistry, 2013, Iran: Ferdowsi University of Mashhad , 2013Conference paper (Other academic)
  • 25.
    Turner, Anthony
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, The Institute of Technology.
    Sekretaryova, Alina
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, The Institute of Technology. Lomonosov Moscow State University, Russia.
    Vagin, Mikhail
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Eriksson, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Karyakin, Arkady
    Lomonosov Moscow State University, Russia.
    Electrochemicalsensing platform based on sol-gel/phenothiazine/enzyme composite films2013In: Advanced Materials World Congress, 2013, VBRI , 2013Conference paper (Other academic)
  • 26.
    Vagin, Mikhail
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Chemical and Optical Sensor Systems. Linköping University, The Institute of Technology.
    Sekretareva, Alina
    Linköping University, Department of Physics, Chemistry and Biology, Chemical and Optical Sensor Systems. Linköping University, The Institute of Technology.
    Sanchez, Rafael
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Lundström, Ingemar
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, The Institute of Technology.
    Winquist, Fredrik
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, The Institute of Technology.
    Eriksson, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Chemical and Optical Sensor Systems. Linköping University, The Institute of Technology.
    Arrays of Screen-Printed Graphite Microband Electrodes as a Versatile Electroanalysis Platform2014In: ChemElectroChem, ISSN 2196-0216, Vol. 1, no 4, p. 755-762Article in journal (Refereed)
    Abstract [en]

    Arrays of microband electrodes were developed by screen printing followed by cutting, which enabled the realization of microband arrays at the cut edge. The microband arrays of different designs were characterized by physical and electro-chemical methods. In both cases, the methods showed that the microband width was around 5 mm. Semi-steady-state cyclic voltammetry responses were observed for redox probes, and chronocoulometric measurements showed the establishment of convergent diffusion regimes characterized by current densities similar to those of a single microelectrode. The analytical performance of the electrode system and its versatility were illustrated with two electrochemical assays: detection of ascorbic acid through direct oxidation and a mediated glucose biosensor fabricated by dip coating. Due to convergent mass transport, both systems showed an enhancement in their analytical characteristics. The developed approach can be adapted to automated electrode recovery.

  • 27.
    Vagin, Mikhail
    et al.
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Trashin, Stanislav A.
    University of Antwerp, Belgium.
    Beloglazkina, Elena K.
    Moscow MV Lomonosov State University, Russia.
    Majouga, Alexander G.
    Moscow MV Lomonosov State University, Russia.
    Direct reagentless detection of the affinity binding of recombinant His-tagged firefly luciferase with a nickel-modified gold electrode2015In: Mendeleev communications (Print), ISSN 0959-9436, E-ISSN 1364-551X, Vol. 25, no 4, p. 290-292Article in journal (Refereed)
    Abstract [en]

    The direct reagentless electrochemical detection of recombinant firefly luciferase binding with a gold electrode modified with nickel complex of 1,16-di[4-(2,6-dihydroxycarbonyl)pyridyl]-1,16-dioxa-8,9-dithiahexadecane has been carried out.

  • 28.
    Vagin, Mikhail Y
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Chemical and Optical Sensor Systems. Linköping University, The Institute of Technology.
    Lundström, Ingemar
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, The Institute of Technology.
    Turner, Anthony
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, The Institute of Technology.
    Beni, Valerio
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, The Institute of Technology.
    Eriksson, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Chemical and Optical Sensor Systems. Linköping University, The Institute of Technology.
    Boron-doped diamond microelectrode arrays for electrochemical monitoring of antibiotics contamination in water2014In: 15th International Conference on Electroanalysis (ESEAC), 2014Conference paper (Other academic)
    Abstract [en]

    The improvement of water management and increasing the access to safe drinking water can develop the quality of life for millions of people world-wide and reduce child mortality due to water-borne diseases [1]. Sweden was recently affected by the lack of appropriate water management which resulted in microbial contamination and tens of thousands of people falling ill [2]. Pollution with chemical compounds is also a waterworks concern. The appearance of pharmaceuticals such as antibiotics in raw water affects the cleaning processes at waterworks [3]. Substances which are not, or are only partly, eliminated in the sewage treatment plant will reach the surface water where they may affect organisms of different trophic levels and cause, for example, the of antibiotics resistance [4]. The inhibition of bacteria of waste water plants by antibiotics may seriously affect organic matter degradation. The efficiency of nitrification as an important step in waste water purification, can be decreased by antibiotics inhibition [5]. Boron-doped diamond (BDD) is an advanced electrode material that possesses the combination of good electrical conductivity achieved via film doping and the extreme chemical inertness of diamond, which gives rise to a number of highly desirable properties of BDD as electrode material: a wide potential window in aqueous media allows electrochemical measurements at both extreme anodic and cathodic potentials, very low capacitive currents leads to a sensitivity increase and extreme chemical and structural inertness prevents electrode fouling [6]. Usage of a microelectrode array as the working electrode offers a variety of benefits for electroanalysis: an improvement of the analytical performance in comparison with macroelectrodes under planar diffusion, higher signal-to-noise ratios due to low capacitive currents at the small surface area, shorter response times and less sensitivity to variations in the water flow rate. The BDD arrays of this work contain 2900 microelectrodes (10 mm diameter each) and have been used for the detection of antibiotics (ofloxacine and canamycin A) in water with high amplitude pulse voltammetry processed by multivariate data analysis. The detection limits observed in monitoring mode were comparable with the characteristics of standard protocols of antibiotics detection, which opens the possibility for continuous monitoring of water.

    [1] The United Nations, World Water Development Report 4, 2012; [2] Lindberg, A. et al.,

    FOI-R--3376--SE, 2011; Dryselius, R.; National Food Agency, Sweden, 2012; [3] Kummerer

    K. Chemosphere, 2009, 75, 417; [4] Kummerer K. Chemosphere, 2009, 75, 435; [5]

    Dokianakis, S.N. et al., Water Sci. Technol. 50, 341; [6] Goeting, C. et al.,

    NewDiam.Front.C.Tech. 1999, 9, 207; Compton, R. et al., Electroanal. 2003, 15, 1349.

     

  • 29.
    Vagin, Mikhail Y
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Chemical and Optical Sensor Systems. Linköping University, The Institute of Technology.
    Sekretaryova, Alina N
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, The Institute of Technology.
    Reategui, Rafael Sanchez
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics.
    Lundström, Ingemar
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics.
    Turner, Anthony
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, The Institute of Technology.
    Eriksson, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Chemical and Optical Sensor Systems. Linköping University, The Institute of Technology.
    Screen-printed graphite microbands as a versatile biosensor platform2014In: 24th Anniversary World Congress on Biosensors – Biosensors 2014, Elsevier, 2014Conference paper (Other academic)
    Abstract [en]

    The use of extremely small working electrodes offers a variety of benefits for electroanalysis. The enhanced mass transport as a result of convergent diffusion is the most important advantage of microdimensional electrodes and results in improved of analytical performance The low detectable-currents problem can be solved by single microelectrode multiplication into an array, thus combining the advantages of enhanced mass transport and high output signals. The microband is one of the most cost-effective and easy-fabricated geometries for microelectrodes. The microband width is a critical microscopic dimension of the electrode, which maintains the dominance of convergent diffusion, whereas the microband length is macroscopic and ensures registration of high currents.

    Graphite screen-printing on a plastic support is a standard technology for large-scale production of low cost electrochemical devices. This has been combined with simple guillotine cutting to fabricate of microband arrays for autonomous environmental and clinical monitoring.

    Single-layer and multilayer microband arrays of different band lengths were produced and characterised using optical and electrochemical methods. The critical dimension for the microband width to facilitate convergent diffusion was assessed electrochemically and found to be in the order of 5 microns. The developed electrode structures were used as a versatile platform for the manufacture of model electroanalytical systems. Direct oxidation of ascorbic acid was explored at the microband arrays and a glucose biosensor based on mediated and immobilised glucose oxidase was fabricated. Both examples yielded significant enhancement of the analytical performance.

    A: the layout of the screen-printed graphite microband array of 5 electrode layers. B: voltammmetric responses obtained at the microband arrays.

    Acknowledgement: Formas and Security Link for financial support; David Nilsson (Acreo) for screen-printing.

  • 30.
    Vagin, Mikhail Y
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Chemical and Optical Sensor Systems. Linköping University, The Institute of Technology.
    Sekretaryova, Alina N
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, The Institute of Technology.
    Reategui, Rafael Sanchez
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, The Institute of Technology.
    Lundström, Ingemar
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, The Institute of Technology.
    Turner, Anthony
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, The Institute of Technology.
    Eriksson, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Chemical and Optical Sensor Systems. Linköping University, The Institute of Technology.
    Screen-printed graphite microbands for electroanalysis2014In: 15th International Conference on Electroanalysis (ESEAC), 2014Conference paper (Other academic)
  • 31.
    Vagin, Mikhail Yu.
    et al.
    Linköping University, Faculty of Science & Engineering. Linköping University, Department of Physics, Chemistry and Biology, Chemical and Optical Sensor Systems.
    Jeerapan, Itthipon
    Linköping University, Faculty of Science & Engineering. Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Hat Yai, Songkla, Thailand.
    Wannapob, Rodtichoti
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, Faculty of Science & Engineering. Hat Yai, Songkla, Thailand.
    Thavarungkul, Panote
    Hat Yai, Songkla, Thailand.
    Kanatharana, Proespichaya
    Hat Yai, Songkla, Thailand.
    Anwar, Nargis
    Dublin Road, Dundalk, County Louth, Ireland.
    McCormac, Timothy
    Dublin Road, Dundalk, County Louth, Ireland.
    Eriksson, Mats
    Linköping University, Faculty of Science & Engineering. Linköping University, Department of Physics, Chemistry and Biology, Chemical and Optical Sensor Systems.
    Turner, Anthony P.F
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, Faculty of Science & Engineering.
    Jager, Edwin W.H.
    Linköping University, Department of Physics, Chemistry and Biology, Sensor and Actuator Systems. Linköping University, Faculty of Science & Engineering.
    Wing Cheung, Mak
    Linköping University, Department of Physics, Chemistry and Biology, Sensor and Actuator Systems. Linköping University, Faculty of Science & Engineering.
    Water-processable polypyrrole microparticle modules for direct fabrication of hierarchical structured electrochemical interfaces2016In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 190, p. 495-503Article in journal (Refereed)
    Abstract [en]

    Hierarchically structured materials (HSMs) are becoming increasingly important in catalysis, separation and energy applications due to their advantageous diffusion and flux properties. Here, we introduce a facile modular approach to fabricate HSMs with tailored functional conducting polypyrrole microparticles (PPyMP). The PPyMPs were fabricated with a calcium carbonate (CaCO3) template-assisted polymerization technique in aqueous media at room temperature, thus providing a new green chemistry for producing water-processable functional polymers. The sacrificial CaCO3 template guided the polymerization process to yield homogenous PPyMPs with a narrow size distribution. The porous nature of the CaCO3 further allows the incorporation of various organic and inorganic dopants such as an electrocatalyst and redox mediator for the fabrication of functional PPyMPs. Dawson-type polyoxometalate (POM) and methylene blue (MB) were chosen as the model electrocatalyst and electron mediator dopant, respectively. Hierarchically structured electrochemical interfaces were created simply by self-assembly of the functional PPyMPs. We demonstrate the versatility of this technique by creating two different hierarchical structured electrochemical interfaces: POM-PPyMPs for hydrogen peroxide electrocatalysis and MB-PPyMPs for mediated bioelectrocatalysis. We envision that the presented design concept could be extended to different conducting polymers doped with other functional organic and inorganic dopants to develop advanced electrochemical interfaces and to create high surface area electrodes for energy storage.

  • 32.
    Vagin, Mikhail Yu
    et al.
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Sekretareva, Alina
    Linköping University, Department of Physics, Chemistry and Biology, Chemical and Optical Sensor Systems. Linköping University, Faculty of Science & Engineering.
    Lindgren, Petter
    Håkansson, Anna
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    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.
    Syväjärve, Mikael
    Yakimova, Rositsa
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Direct bioelectrocatalysis on anodized epitaxial graphene2015In: Program of the XXIII International Symposium on Bioelectrochemistry and Bioenergetics of the Bioelectrochemical Society14-18 June, 2015Malmö, Sweden, Lausanne: Bioelectrochemical Society , 2015, p. 170-170Conference paper (Other academic)
    Abstract [en]

    Graphene as a nanomaterial consisting of a single layer sheets of atoms of carbon in hexagonal arrangement is making a significant impact in variety of technologies such as energy storage and chemical analysis. The significant attention paid to this thinnest nanomaterial resulted in thousands of patent applications is due to its staggering properties. Due to the planar conjugation of the sp2bonds in graphene, two-dimensional electrical conduction is highly efficient. On the contrary, the efficiency of electron exchange at the out-of-plane of the graphene sheet is small. The significant difference of the densities of electronic states at in-plane and out-of-plane of graphene sheet determines two distinct structural contributions (basal and edge plane respectively) to the behavior of all graphitic materials yielding the chemical and electrochemical anisotropy. Being the simplest building block of graphitic materials, graphene offers the possibility to study the behavior on the simplest level of structural organization. However, the major effort of the recent electrochemical studies of graphene were done using a bulk materials based on graphene flakes possessing the domination of edges of high reactivity. The planar orientation of graphene sheets with controllable exposure of basal plane is achievable via the growth by chemical vapor deposition or by epitaxial flash annealing on crystalline structures of silicon carbide. The slow growth of graphene onto crystalline support during annealing in the inert atmosphere results in a development of a high quality graphene monolayer attached to the solid insulating support. The creation of sp3-type reactive defects on the basal plane of graphite can be achieved by anodization at high anodic potentials.

    We developed the procedure for the real-time monitoring of epitaxial graphene anodization. The changes of electrochemical properties of graphene monolayer with anodization have been comparatively investigated by electrochemical methods. The estimation of specific capacitance in pure electrolyte and in conditions of Faradaic process has been carried out. Finally, the direct electrocatalysis of laccase (Trametes versicolor) has been used as an electrode reaction to probe the reactivities of anodized epitaxial graphene and conventional carbon materials.

  • 33.
    Wannapob, Rodtichoti
    et al.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, Faculty of Science & Engineering. Prince Songkla University, Thailand.
    Vagin, Mikhail
    Linköping University, Department of Physics, Chemistry and Biology.
    Jeerapan, Itthipon
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, Faculty of Science & Engineering. Prince Songkla University, Thailand.
    Mak, Wing Cheung
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, Faculty of Science & Engineering.
    Pure Nanoscale Morphology Effect Enhancing the Energy Storage Characteristics of Processable Hierarchical Polypyrrole2015In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 31, no 43, p. 11904-11913Article in journal (Refereed)
    Abstract [en]

    We report a new synthesis approach for the precise control of wall morphologies of colloidal polypyrrole microparticles (PPyMPs) based on a time-dependent template-assisted polymerization technique. The resulting PPyMPs are water processable, allowing the simple and direct fabrication of multilevel hierarchical PPyMPs films for energy storage via a self-assembly process, whereas convention methods creating hierarchical conducting films based on electrochemical polymerization are complicated and tedious. This approach allows the rational design and fabrication of PPyMPs with well-defined size and tunable wall morphology, while the chemical composition, zeta potential, and microdiameter of the PPyMPs are well characterized. By precisely controlling the wall morphology of the PPyMPs, we observed a pure nanoscale morphological effect of the materials on the energy storage performance. We demonstrated by controlling purely the wall morphology of PPyMPs to around 100 nm (i.e., thin-walled PPyMPs) that the thin-walled PPyMPs exhibit typical supercapacitor characteristics with a significant enhancement of charge storage performance of up to 290% compared to that of thick-walled PPyMPs confirmed by cyclic voltametry, galvanostatic charge-discharge, and electrochemical impedance spectroscopy. We envision that the present design concept could be extended to different conducting polymers as well as other functional organic and inorganic dopants, which provides an innovative model for future study and understanding of the complex physicochemical phenomena of energy-related materials.

  • 34.
    Wijeratne, Kosala
    et al.
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Ail, Ujwala
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Brooke, Robert
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Vagin, Mikhail
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Liu, Xianjie
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Fahlman, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Crispin, Xavier
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Bulk electronic transport impacts on electron transfer at conducting polymer electrode-electrolyte interfaces.2018In: Proceedings of the National Academy of Sciences of the United States of America, ISSN 0027-8424, E-ISSN 1091-6490, no 7, p. 11899-11904Article in journal (Refereed)
    Abstract [en]

    Electrochemistry is an old but still flourishing field of research due to the importance of the efficiency and kinetics of electrochemical reactions in industrial processes and (bio-)electrochemical devices. The heterogeneous electron transfer from an electrode to a reactant in the solution has been well studied for metal, semiconductor, metal oxide, and carbon electrodes. For those electrode materials, there is little correlation between the electronic transport within the electrode material and the electron transfer occurring at the interface between the electrode and the solution. Here, we investigate the heterogeneous electron transfer between a conducting polymer electrode and a redox couple in an electrolyte. As a benchmark system, we use poly(3,4-ethylenedioxythiophene) (PEDOT) and the Ferro/ferricyanide redox couple in an aqueous electrolyte. We discovered a strong correlation between the electronic transport within the PEDOT electrode and the rate of electron transfer to the organometallic molecules in solution. We attribute this to a percolation-based charge transport within the polymer electrode directly involved in the electron transfer. We show the impact of this finding by optimizing an electrochemical thermogalvanic cell that transforms a heat flux into electrical power. The power generated by the cell increased by four orders of magnitude on changing the morphology and conductivity of the polymer electrode. As all conducting polymers are recognized to have percolation transport, we believe that this is a general phenomenon for this family of conductors.

  • 35.
    Zeglio, Erica
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Vagin, Mikhail
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Musumeci, Chiara
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Ajjan, Fátima
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Gabrielsson, Roger
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, Faculty of Science & Engineering.
    Trinh, Xuan thang
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Nguyen, Son Tien
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Maziz, Ali
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, Faculty of Science & Engineering.
    Solin, Niclas
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Conjugated Polyelectrolyte Blends for Electrochromic and Electrochemical Transistor Devices2015In: Chemistry of Materials, ISSN 0897-4756, E-ISSN 1520-5002, Vol. 27, no 18, p. 6385-6393Article in journal (Refereed)
    Abstract [en]

    Two self-doped conjugated polyelectrolytes, having semiconducting and metallic behaviors, respectively, have been blended from aqueous solutions in order to produce materials with enhanced optical and electrical properties. The intimate blend of two anionic conjugated polyelectrolytes combine the electrical and optical properties of these, and can be tuned by blend stoichiometry. In situ conductance measurements have been done during doping of the blends, while UV vis and EPR spectroelectrochemistry allowed the study of the nature of the involved redox species. We have constructed an accumulation/depletion mode organic electrochemical transistor whose characteristics can be tuned by balancing the stoichiometry of the active material.

  • 36.
    Zhybak, Mikael
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, The Institute of Technology.
    Beni, Valerio
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, The Institute of Technology.
    Dempsey, Eithne
    Centre for Research in Electroanalytical Technologies, Department of Science, Dublin, Ireland.
    Vagin, Mikhail Y
    Linköping University, Department of Physics, Chemistry and Biology, Chemical and Optical Sensor Systems. Linköping University, The Institute of Technology.
    Turner, Anthony
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, The Institute of Technology.
    Korpan, Yaroslav
    Laboratory of Biomolecular Electronics, Institute of Molecular Biology and Genetics, National Academy of Sciences of Ukraine, Kyiv, Ukraine.
    Copper/Nafion/PANI Nanocomposite as an electrochemical transducer for creatinine and urea enzymatic biosensing2014In: 24th Anniversary World Congress on Biosensors – Biosensors 2014, Elsevier, 2014Conference paper (Other academic)
    Abstract [en]

    Chronic Kidney diseases (CKD) affect, to different degrees, ca. 25 million Americans and 19 million Europeans. Monitoring of creatinine and urea levels is of great importance for a correct evaluation of the status of patients and for their treatment. In this paper, we present the development of creatinine and urea enzymatic biosensors, based on a novel ammonium ion-specific Copper/Nafion/Polyanyline (PANI) nanocomposite electrode (Fig. 1A), and suitable for PoC and decentralised diagnostic applications. . Studies on the nanocomposite electrode revealed its high sensitivity and specificity towards ammonium, in respect to amino acids, creatinine and urea, with response range between 5 and 75 μM (Fig. 1B) and with a detection limit of 1 μM. To demonstrate its suitability as transducer in biosensors, creatinine and urea biosensors were fabricated by immobilising creatinine deiminase or urease, respectively, on the nanocomposite surface. Optimisation of the enzyme immobilisation demonstrated that the incorporation of lactitol markedly improved the stability of the biosensors. The response range of the creatinine biosensor was 2 to 100 μM, which fits well with the normal levels of creatinine in healthy people (30-150 µM).

    The urea biosensor had a response range of 5 to 100 µM. A limit of quantification of 1 µM was achieved for both the biosensors.

    Evaluation of the performance of the biosensors in real sample matrices and cross reactivity studies are currently on-going. We envisage that the proposed design will be particularly compatible with fully-printed systems thus offering a viable route to the mass production of inexpensive sensors for mobile health.

     

     

  • 37.
    Zhybak, M.T.
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, Faculty of Science & Engineering. Laboratory of Biomolecular Electronics, Institute of Molecular Biology and Genetics, National Academy of Sciences of Ukraine, Kyiv, Ukraine.
    Beni, Valerio
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, Faculty of Science & Engineering.
    Vagin, Mikhail
    Linköping University, Department of Physics, Chemistry and Biology, Chemical and Optical Sensor Systems. Linköping University, Faculty of Science & Engineering.
    Dempsey, Eithne
    Centre for Research in Electroanalytical Technologies, Department of Science, ITT Dublin, Tallaght, Dublin, Ireland.
    Turner, Anthony
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, Faculty of Science & Engineering.
    Korpan, Y
    Laboratory of Biomolecular Electronics, Institute of Molecular Biology and Genetics, National Academy of Sciences of Ukraine,Kyiv, Ukraine.
    Creatinine and urea biosensors based on a novel ammonium ion-selective copper-polyaniline nano-composite2016In: Biosensors & bioelectronics, ISSN 0956-5663, E-ISSN 1873-4235, Vol. 77, p. 505-511Article in journal (Refereed)
    Abstract [en]

    The use of a novel ammonium ion-specific copper-polyaniline nano-composite as transducer for hydrolase-based biosensors is proposed. In this work, a combination of creatinine deaminase and urease has been chosen as a model system to demonstrate the construction of urea and creatinine biosensors to illustrate the principle. Immobilisation of enzymes was shown to be a crucial step in the development of the biosensors; the use of glycerol and lactitol as stabilisers resulted in a significant improvement, especially in the case of the creatinine, of the operational stability of the biosensors (from few hours to at least 3 days). The developed biosensors exhibited high selectivity towards creatinine and urea. The sensitivity was found to be 85±3.4 mA M−1 cm−2 for the creatinine biosensor and 112±3.36 mA M−1 cm−2 for the urea biosensor, with apparent Michaelis–Menten constants (KM,app), obtained from the creatinine and urea calibration curves, of 0.163 mM for creatinine deaminase and 0.139 mM for urease, respectively. The biosensors responded linearly over the concentration range 1–125 µM, with a limit of detection of 0.5 µM and a response time of 15 s.

    The performance of the biosensors in a real sample matrix, serum, was evaluated and a good correlation with standard spectrophotometric clinical laboratory techniques was found.

  • 38.
    Zhybak, Mykhailo T.
    et al.
    Linköping University, Faculty of Science & Engineering. Linköping University, Department of Physics, Chemistry and Biology. Institute of Molecular Biology and Genetics, NAS of Ukraine, Kyiv, 03680, Ukraine .
    Vagin, Mikhail Yu.
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Department of Physics, Chemistry and Biology. Linköping University, Faculty of Science & Engineering.
    Beni, Valerio
    ACREO Swedish ICT, -601 74, Norrköping, SE, Sweden .
    Liu, Xianjie
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Dempsey, Eithne
    Centre for Research in Electroanalytical Technologies, Department of Science, Institute of Technology Tallaght, Tallaght, Dublin, Ireland .
    Turner, Anthony P. F.
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, Faculty of Science & Engineering.
    Korpan, Yaroslav I.
    Institute of Molecular Biology and Genetics, NAS of Ukraine, Kyiv, 03680, Ukraine .
    Direct detection of ammonium ion by means of oxygen electrocatalysis at a copper-polyaniline composite on a screen-printed electrode.2016In: Microchimica Acta, ISSN 0026-3672, E-ISSN 1436-5073, Vol. 183, no 6, p. 1981-1987Article in journal (Refereed)
    Abstract [en]

    A novel electrocatalytic material for oxygen reduction, based on polyaniline in combinationwith copper, was developed and utilised for the direct voltammetric quantification of ammonium ions. Consecutive electrode modification by electrodeposited copper, a Nafion membrane and electropolymerised polyaniline resulted in an electrocatalytic composite material which the retained conductivity at neutral pH. Ammonia complex formation with Cu (I) caused the appearance of oxygen electrocatalysis, which was observed as an increase in cathodic current. This Faradaic phenomenon offered the advantage of direct voltammetric detection and was utilised for ammonium electroanalysis. The developed quantification protocol was applied for ammonium assay in human serum and compared with the routine approach for clinical analysis.

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