TY  - JOUR
A1  - Kapp, A.
A1  - Beissenhirtz, Moritz Karl
A1  - Geyer, F.
A1  - Scheller, F.
A1  - Viezzoli, Maria Silvia
A1  - Lisdat, Fred
T1  - Electrochemical and sensorial behavior of SOD mutants immobilized on gold electrodes in aqueous/organic solvent mixtures
JF  - Electroanalysis : an international journal devoted to fundamental and practical aspects of electroanalysis
N2  - A cysteine mutant of a monomeric human Cu, Zn-SOD (Glycine 61, Serine 142) has been immobilized directly on gold electrodes using the thiol groups introduced. The electrochemical behavior of the surface confined protein was studied in mixtures of aqueous buffer and DMSO up to an organic solvent content of 60%. The formal potential was found to be rather independent of the DMSO content. However, half peak width increased and the redoxactive amount clearly decreased with raising DMSO content. In addition, the kinetics of the heterogeneous electron transfer became slower; but still a quasireversible electrochemical conversion of the mutant SOD was feasible. Thus, the electrodes were applied for sensorial superoxide detection. At a potential of +220 mV vs. Ag/AgCl advantage was taken of the partial oxidation reaction of the enzyme. A defined superoxide signal was obtained in solutions up to 40% DMSO. The sensitivity of the mutant electrodes decreased linearly with the organic solvent content in solution but was still higher compared to conventional cyt.c based sensors. At DMSO concentrations higher than 40% no sensor response was detected.
KW  - SOD
KW  - mutants
KW  - gold electrodes
KW  - DMSO
KW  - electrochemistry
Y1  - 2006
U6  - https://doi.org/10.1002/elan.200603620
SN  - 1040-0397
VL  - 18
SP  - 1909
EP  - 1915
PB  - Wiley
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Kapp, Andreas
A1  - Beissenhirtz, Moritz Karl
A1  - Geyer, F.
A1  - Scheller, Frieder W.
A1  - Viezzoli, Maria Silvia
A1  - Lisdat, Fred
T1  - Electrochemical and sensorial behaviour of SOD mutants immobilized on gold electrodes in aqueous / organic solvent mixtures
Y1  - 2006
UR  - http://www3.interscience.wiley.com/cgi-bin/jhome/26571/
U6  - https://doi.org/10.1002/elan.200603620
SN  - 1040-0397
ER  - 
TY  - JOUR
A1  - Beissenhirtz, Moritz Karl
A1  - Scheller, Frieder W.
A1  - Viezzoli, Maria Silvia
A1  - Lisdat, Fred
T1  - Engineered superoxide dismutase monomers for superoxide biosensor applications
N2  - Because of its high reaction rate and specificity, the enzyme superoxide dismutase (SOD) offers great potential for the sensitive quantification of superoxide radicals in electrochemical biosensors. In this work, monomeric mutants of human Cu,Zn-SOD were engineered to contain one or two additional cysteine residues, which could be used to bind the protein to gold surfaces, thus making the use of promotor molecules unnecessary. Six mutants were successfully designed, expressed, and purified. All mutants bound directly to unmodified gold surfaces via the sulfur of the cysteine residues and showed a quasireversible, direct electron transfer to the electrode. Thermodynamic and kinetic parameters of the electron transfer were characterized and showed only slight variations between the individual mutants. For one of the mutants, the interaction with the superoxide radical was studied in more detail. For both partial reactions of the dismutation, an interaction between protein and radical could be shown. In an amperometric biosensorial approach, the SOD-mutant electrode was successfully applied for the detection of superoxide radicals. In the oxidation region, the electrode surpassed the sensitivity of the commonly used cytochrome c electrodes by similar to 1 order of magnitude while not being limited by interferences, but the electrode did not fully reach the sensitivity of dimeric Cu,Zn-SOD immobilized on MPA-modified gold
Y1  - 2006
UR  - http://pubs.acs.org/journal/ancham
U6  - https://doi.org/10.1021/Ac051465g
SN  - 0003-2700
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  -