TY - GEN A1 - Riepl, Michael A1 - Mirsky, Vladimir M. A1 - Novotny, Ivan A1 - Tvarozek, Vladimir A1 - Rehacek, Vlastimil A1 - Wolfbeis, Otto S. T1 - Optimization of capacitive affinity sensors: drift suppression and signal amplification T2 - Analytica Chimica Acta N2 - The detection limit of capacitive affinity sensors based on the gold–alkanethiol system can be improved by optimization of sensor preparation and by signal amplification. The dissociation of the gold–sulfur binding is often a critical point leading to operative errors of such sensors. The stability of self-assembled monolayers prepared with different thiols on gold electrodes in aqueous and organic solvents was studied by the capacitive technique. The results show that monolayers made of 16-mercaptohexadecanoic acid are stable in aqueous solution and can be hardly extracted from a gold surface by ethanol, methanol, or dioxane, while a considerable damage of self-assembled monolayers was observed due to incubation in chloroform or dimethylformamide. In contrast, self-assembled monolayers made from short-chain disulfides or thiols (such as 3,3′-dithio-bis(propionic acid N-hydroxysuccinimide ester) or 11-mercaptoundecanoic acid) displayed a poor stability in aqueous phase. Capacitive affinity sensors based on these short-chain thiols showed a considerable drift of the signal. The use of long-chain thiols resulted in a stable signal; it was applied to compare capacitive effects due to immobilization of different biological molecules and for preparation of different biosensors. The response of capacitive biosensors can be amplified by formation of a sandwich structure. This principle was illustrated by subsequent adsorption of polyclonal anti-HSA after binding of HSA with a sensor for HSA based on monoclonal antibodies. KW - Affinity sensor KW - Self-assembly KW - Capacitive sensor KW - Signal amplification KW - Immunosensor KW - Biosensor Y1 - 1999 U6 - https://doi.org/10.1016/S0003-2670(99)00195-6 SN - 0003-2670 VL - 392 IS - 1 SP - 77 EP - 84 ER - TY - GEN A1 - Mirsky, Vladimir M. A1 - Riepl, Michael A1 - Krause, Christian A1 - Novotny, Ivan A1 - Splonskowski, Markus A1 - Rehacek, Vlastimil A1 - Tvarozek, Vladimir A1 - Hummel, Helmut A1 - Wolfbeis, Otto S. T1 - Thin film electrodes for capacitive chemo- and biosensors: an optimization of the electrodes geometry T2 - Materials Science Forum KW - Biosensor KW - Capacitance KW - Chemical Sensors KW - Electrode Y1 - 1998 U6 - https://doi.org/10.4028/www.scientific.net/MSF.287-288.423 SN - 1662-9752 VL - 287-288 SP - 423 EP - 426 ER - TY - GEN A1 - Zynio, Stepan A. A1 - Samoylov, Anton V. A1 - Surovtseva, Elena R. A1 - Mirsky, Vladimir M. A1 - Shirshov, Yuri M. T1 - Bimetallic layers increase sensitivity of affinity sensors based on surface plasmon resonance T2 - Sensors N2 - Two metals are used in resonant layers for chemical sensors based on surface plasmon resonance (SPR) - gold and silver. Gold displays higher shift of the resonance angle to changes of ambient refraction index and is chemically stable. Silver posses narrower resonance curve thus providing a higher signal/noise ratio of SPR chemical sensors, but has a poor chemical stability. A new structure of resonant metallic film based on bimetallic silver/gold layers (gold as an outer layer) is suggested. It combines advantages of both gold and silver resonant layers. Bimetallic resonant films display so high shift of resonance angle on changes of ambient refraction index as gold films, but show narrower resonance curve, thus providing a higher signal / noise ratio. Additionally, the outer gold layer protects silver against oxidation. KW - Surface plasmon resonance KW - Biosensor KW - Sensitivity KW - Signal / noise ratio Y1 - 2002 U6 - https://doi.org/10.3390/s20200062 SN - 1424-8220 VL - 2 IS - 2 SP - 62 EP - 70 ER - TY - GEN A1 - Cao, Limin A1 - Lin, Hong A1 - Mirsky, Vladimir M. T1 - DNA-based surface plasmon resonance biosensor for enrofloxacin T2 - Analytica Chimica Acta N2 - A DNA-based surface plasmon resonance biosensor for enrofloxacin was developed. Heating denatured DNA immobilized on the gold-coated glass surface was exploited. The immobilization was performed by a layer-by-layer co-deposition with a cationic polymer. The sensor performance was tested with real biological probes. Direct and simple determination of enrofloxacin in milk samples was demonstrated. The sensor response obeys Langmuir binding isotherm being almost linear until about 20 µg per mL. The detection limit in milk samples was estimated to be 3 µg per mL. KW - Surface plasmon resonance KW - Nucleic acid KW - Biosensor KW - Enrofloxacin KW - Fluoroquinolones KW - Layer-by-layer deposition Y1 - 2007 U6 - https://doi.org/10.1016/j.aca.2007.02.034 SN - 0003-2670 VL - 589 IS - 1 SP - 1 EP - 5 ER - TY - GEN A1 - Zhi, Zheng-liang A1 - Drazan, Viktor A1 - Wolfbeis, Otto S. A1 - Mirsky, Vladimir M. T1 - Electrocatalytic activity of DNA on electrodes as an indication of hybridization T2 - Bioelectrochemistry N2 - Electron transfer between metal electrodes and ferro/ferricyanide is completely suppressed at low ionic concentration. We describe here a new phenomenon related to this reaction: an immobilisation of thiolated single-stranded DNA on gold electrodes retains this activity at low ionic strength up to the level corresponding to the high ionic strength. In contrast, a hybridisation of the complementary DNAwith the thiolated single-stranded DNA followed by a binding onto the electrodes, attenuated the electrocatalytic effect. These effects can be used for discrimination between single-stranded DNA and double-stranded DNA and for semi-quantitative measurement of complementary DNA in a sample. KW - DNA KW - DNA-sensor KW - Biosensor KW - Electrocatalysi KW - Hybridisation KW - Oligonucleotide KW - Gene analysis Y1 - 2006 U6 - https://doi.org/10.1016/j.bioelechem.2005.02.006 SN - 1567-5394 VL - 68 IS - 1 SP - 1 EP - 6 ER - TY - GEN A1 - Wrobel, Nadia A1 - Deininger, Werner A1 - Hegemann, Peter A1 - Mirsky, Vladimir M. T1 - Covalent immobilization of oligonucleotides on electrodes T2 - Colloids and Surfaces B: Biointerfaces N2 - 32P-labeled DNA oligomers were immobilized onto self-assembled monolayers formed by carboxy-modified alkylthiols on gold electrodes. The optimal conditions were evaluated by comparing of surface density of oligonucleotides measured for different immobilization conditions before and after desorption of physically adsorbed nucleotides. The results demonstrate that the physical adsorption depends strongly on immobilization conditions being typically 10 times higher than the chemical immobilization. Under optimal immobilization conditions, the surface density of oligonucleotides was more than 20% of the value calculated for a densely packed monolayer. KW - DNA KW - DNA immobilization KW - DNA sensor KW - Biosensor KW - Hybridization Y1 - 2003 U6 - https://doi.org/10.1016/S0927-7765(03)00155-3 SN - 0927-7765 VL - 32 IS - 2 SP - 157 EP - 162 ER -