排序方式: 共有20条查询结果,搜索用时 15 毫秒
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Huseyin Bekir Yildiz Jaime Castillo Dmitrii A. Guschin Levent Toppare Wolfgang Schuhmann 《Mikrochimica acta》2007,159(1-2):27-34
An amperometric biosensor for the detection of phenolic compounds was developed based on the immobilization of tyrosinase
within an Os-complex functionalized electrodeposition polymer. Integration of tyrosinase within the redox polymer assures
efficient catechol recycling between the enzyme and the polymer bound redox sites. The non-manual immobilization procedure
improves the reproducibility of fabrication process, greatly reduces the desorption of the enzyme from the immobilization
layer, and, most importantly prevents fast inactivation of the enzyme by its substrate due to fast redox cycling.
A two-layer sensor architecture was developed involving ascorbic acid oxidase entrapped within an electrodeposition polymer
in a second layer on top of the redox polymer/tyrosinase layer. Using this sensor architecture it was possible to eliminate
the current interference arising from direct ascorbate oxidation up to a concentration of 630 μM ascorbic acid. The effects
of the polymer thickness, the enzyme/polymer ratio, and the applied potential were evaluated with respect to optimal sensor
properties. The sensitivity of the optimized sensors for catechol was 6.1 nA μM−1 with a detection limit of 10 nM, and for phenol 0.15 nA μM−1 with a detection limit of 100 nM. 相似文献
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Dmitrii A. Guschin John Castillo Nina Dimcheva Wolfgang Schuhmann 《Analytical and bioanalytical chemistry》2010,398(4):1661-1673
The design of polymers carrying suitable ligands for coordinating Os complexes in ligand exchange reactions against labile
chloro ligands is a strategy for the synthesis of redox polymers with bound Os centers which exhibit a wide variation in their
redox potential. This strategy is applied to polymers with an additional variation of the properties of the polymer backbone
with respect to pH-dependent solubility, monomer composition, hydrophilicity etc. A library of Os-complex-modified electrodeposition
polymers was synthesized and initially tested with respect to their electron-transfer ability in combination with enzymes
such as glucose oxidase, cellobiose dehydrogenase, and PQQ-dependent glucose dehydrogenase entrapped during the pH-induced
deposition process. The different polymer-bound Os complexes in a library containing 50 different redox polymers allowed the
statistical evaluation of the impact of an individual ligand to the overall redox potential of an Os complex. Using a simple
linear regression algorithm prediction of the redox potential of Os complexes becomes feasible. Thus, a redox polymer can
now be designed to optimally interact in electron-transfer reactions with a selected enzyme. 相似文献
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Adrian Badura Dmitrii Guschin Berndt Esper Tim Kothe Sebastian Neugebauer Wolfgang Schuhmann Matthias Rögner 《Electroanalysis》2008,20(10):1043-1047
Photosystem 2 (PS2) that catalyses light driven water splitting in photosynthesis was ‘wired’ to electrode surfaces via osmium‐containing redox polymers based on poly(vinyl)imidazol. The redox polymer hydrogel worked as both immobilization matrix and electron acceptor for the enzyme. Upon illumination, the enzymatic reaction could be switched on and a catalytic current was observed at the electrode. The catalytic current is directly dependent on the intensity of light used for the excitation of PS2. A typical current density of 45 μA cm?2 at a light intensity of 2.65 mW cm?2 could be demonstrated with a significantly improved operational stability. 相似文献
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Demkiv O Smutok O Paryzhak S Gayda G Sultanov Y Guschin D Shkil H Schuhmann W Gonchar M 《Talanta》2008,76(4):837-846
Novel formaldehyde-selective amperometric biosensors were developed based on NAD(+)- and glutathione-dependent formaldehyde dehydrogenase isolated from a gene-engineered strain of the methylotrophic yeast Hansenula polymorpha. Electron transfer between the immobilized enzyme and a platinized graphite electrode was established using a number of different low-molecular free-diffusing redox mediators or positively charged cathodic electrodeposition paints modified with Os-bis-N,N-(2,2'-bipyridil)-chloride ([Os(bpy)(2)Cl]) complexes. Among five tested Os-containing redox polymers of different chemical structure and properties, complexes of osmium-modified poly(4-vinylpyridine) with molecular mass of about 60 kDa containing diaminopropyl groups were selected. The positively charged cathodic paint exhibited the best electron-transfer characteristics. Moreover, the polymer layers simultaneously served as a matrix for keeping the negatively charged low-molecular cofactors, glutathione and NAD(+), in the bioactive layer. Additionally, covering the enzyme/polymer layer with a negatively charged Nafion membrane significantly decreased cofactors leakage and simultaneously enhanced the sensor' stability. The developed sensors revealed a high selectivity to formaldehyde (FA) and a low cross-sensitivity to other substances (such as, e.g. butyraldehyde, propionaldehyde, acetaldehyde, methylglyoxal). The maximum current value was 34.2+/-0.72 microA/mm(2) (3.05 mm diameter electrode) and the apparent Michaelis-Menten constant (K(M)(app)) derived from the FA calibration curves was 120+/-5mM with a linear detection range for FA up to 20mM. The best observed sensitivity for reagentless sensor was 1.8 nA microM(-1) (358 Am(-2)M(-1)). The developed sensors had a good operational and storage stability. The laboratory prototype of the sensor was applied for FA testing in some real samples of pharmaceutical (formidron), disinfectant (descoton forte) and industrial product (formalin). A good correlation was revealed between the concentration values measured using the developed FdDH-based sensor, an enzymatic method and standard chemical methods of FA determination. 相似文献
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Dmitrii A. Guschin Halyna Shkil Wolfgang Schuhmann 《Analytical and bioanalytical chemistry》2009,395(6):1693-1706
Electrodeposition polymers can be precipitated on electrode surfaces upon electrochemical-induced modulations of the pH value
in the diffusion zone in front of the electrode. The formed polymer films can be used as immobilization matrices in amperometric
biosensors. In order to rationally control the thus obtained biosensor properties, it is indispensable to develop strategies
for the reproducible synthesis of electrodeposition polymers as well as methods for the non-manual and reproducible sensor
fabrication. Based on instrumental developments such as a specifically designed parallel synthesizer with improved stirring
and temperature control, an automatic pipetting robot for the preparation of the monomer mixtures and controlled removal of
polymerization inhibitors, the reproducible synthesis of libraries of electrodeposition polymers was achieved. Moreover, the
polymerization process could be monitored using in-line thermocouples, and it could be shown that the chosen strategies led
to reproducible polymerization reactions. By adaptation of an electrochemical robotic system integrating a Au microtiter plate
and automatic electrode cleaning by means of a polishing wheel reproducible biosensor fabrication using glucose oxidase as
a model enzyme could be demonstrated. These results open the route for the rational development of biosensors and control
of the sensor properties by choosing specifically designed electrodeposition polymers.
相似文献
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Burtovoy V. S. Akimenko S. A. Artamonov A. V. Blik A. M. Brekhovskikh V. V. Gorin A. M. Donskov S. V. Inyakin A. V. Kolosov V. N. Kurshetsov V. F. Lishin V. A. Medynsky M. V. Mikhailov Yu. V. Obraztsov V. F. Polyakov V. A. Romanovsky V. I. Rykalin V. I. Sadovsky A. S. Samoilenko V. D. Stenyakin O. V. Uvarov V. A. Filin A. P. Khaustov G. V. Kholodenko S. A. Tchikilev O. G. Yushchenko O. P. Guschin E. N. Duk V. A. Kravtsov V. I. Kudenko Yu. G. Polyarush A. Yu. Filippov S. N. Khudyakov A. A. Bychkov V. N. Zalikhanov B. Zh. Kekelidze G. D. Lysan V. M. 《Journal of Experimental and Theoretical Physics》2020,131(6):928-939
Journal of Experimental and Theoretical Physics - On the statistics of ~1.7 × 108 interactions of positively charged kaons on copper nuclei, coherent events of the K+π0 system production... 相似文献
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