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- Sekretareva, Alina, et al.
(author)
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Total phenol analysis of water using a laccase-based microsensor array
- 2015
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In: Program of the XXIII International Symposium on Bioelectrochemistry and Bioenergetics of the Bioelectrochemical Society. 14-18 June, 2015. Malmö, Sweden. - Lausanne : Bioelectrochemical Society. ; , s. 155-155
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Conference paper (other academic/artistic)abstract
- 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.
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- Vagin, Mikhail Yu, et al.
(author)
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Direct bioelectrocatalysis on anodized epitaxial graphene
- 2015
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In: Program of the XXIII International Symposium on Bioelectrochemistry and Bioenergetics of the Bioelectrochemical Society14-18 June, 2015Malmö, Sweden. - Lausanne : Bioelectrochemical Society. ; , s. 170-170
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Conference paper (other academic/artistic)abstract
- 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.
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