TY  - JOUR
A1  - Krylov, Andrey V.
A1  - Beissenhirtz, Moritz Karl
A1  - Adamzig, Holger
A1  - Scheller, Frieder W.
A1  - Lisdat, Fred
T1  - Thick-film electrodes for measurement of superoxide and hydrogen peroxide based on direct protein-electrode contacts
N2  - Cytochrome c was immobilized on screen-printed thick-film gold electrodes by a self-assembly approach using mixed monolayers of mercaptoundecanoic acid and mercaptoundecanol. Cyclic voltammetry revealed quasi-reversible electrochemical behavior of the covalently fixed protein with a formal potential of +10 mV vs. Ag/AgCl. Polarized at +150 mV vs. Ag/AgCl the electrode was found to be sensitive to superoxide radicals in the range 300-1200 nmol L-1. Compared with metal needle electrodes sensitivity and reproducibility could be improved and combined with the easiness of preparation. This allows the fabrication of disposable sensors for nanomolar superoxide concentrations. By changing the electrode potential the sensor can be switched from response to superoxide radicals to hydrogen peroxide-another reactive oxygen species. H2O2 sensitivity can be provided in the range 10-1000 mumol L-1 which makes the electrode suitable for oxidative stress studies
Y1  - 2004
ER  - 
TY  - JOUR
A1  - Krylov, Andrey V.
A1  - Pfeil, Wolfgang
A1  - Lisdat, Fred
T1  - Denaturation and renaturation of cytochrome c immobilized on gold electrodes in DMSO-containing buffers
N2  - Cytochrome c (cyt c) was immobilized on surface-modified gold electrodes using a self-assembling approach. The resulting cyt c electrode was studied using cyclic voltammetry. Compared to pure phosphate buffer, cyt c electrodes exhibited in DMSO-containing solutions lower oxidation and reduction peak currents, which originated from a decrease in the addressable electro-active amount of the surface-immobilized protein. This is associated with the process of protein denaturation. The denaturation kinetics can be described by a sum of two processes with time constants differing by more than one order of magnitude. The subsequent change of the aqueous/organic medium back to a pure aqueous buffer resulted in a shift of the formal potential to its initial value and a partial recovery of the peak current. This can be attributed to the renaturation of the cyt c. The extent of renaturation depended on the organic solvent/water ratio of the mixture used. The kinetics of protein renaturation were similar to those of the denaturation process. (C) 2004 Elsevier B.V. All rights reserved
Y1  - 2004
ER  - 
TY  - JOUR
A1  - Krylov, Andrey. V.
A1  - Adamzig, H.
A1  - Walter, A. D.
A1  - Loechel, B.
A1  - Kurth, E.
A1  - Pulz, O.
A1  - Szeponik, Jan
A1  - Wegerich, Franziska
A1  - Lisdat, Fred
T1  - Parallel generation and detection of superoxide and hydrogen peroxide in a fluidic chip
JF  - Sensors and actuators : B, Chemical
N2  - A fluidic chip system was developed, which combines a stable generation of superoxide radicals and hydrogen peroxide with their sensorial detection. The generation of both reactive oxygen species was achieved by immobilization of xanthine oxidase on controlled pore glass in a reaction chamber. Antioxidants can be introduced into the fluidic chip system by means of mixing chamber. The detection of both species is based on the amperometric principle using a biosensor chip with two working electrodes. As sensing protein for both electrodes cytochrome c was used. The novel system was designed for the quantification of the antioxidant efficiency of different potential scavengers of the respective reactive species in an aqueous medium. Several model antioxidants such as ascorbic acid or catalase have been tested under flow conditions.
KW  - biosensor
KW  - cytochrome c
KW  - flow system
KW  - reactive oxygen species
KW  - antioxidant
Y1  - 2006
U6  - https://doi.org/10.1016/j.snb.2005.11.062
SN  - 0925-4005
VL  - 119
IS  - 1
SP  - 118
EP  - 126
PB  - Elsevier
CY  - Lausanne
ER  -