TY  - JOUR
A1  - Yarman, Aysu
A1  - Nagel, Thomas
A1  - Gajovic-Eichelmann, Nenad
A1  - Fischer, Anna
A1  - Wollenberger, Ursula
A1  - Scheller, Frieder W.
T1  - Bioelectrocatalysis by Microperoxidase-11 in a Multilayer Architecture of Chitosan Embedded Gold Nanoparticles
JF  - Electroanalysis : an international journal devoted to fundamental and practical aspects of electroanalysis
N2  - We report on the redox behaviour of the microperoxidase-11 (MP-11) which has been electrostatically immobilized in a matrix of chitosan-embedded gold nanoparticles on the surface of a glassy carbon electrode. MP-11 contains a covalently bound heme c as the redox active group that exchanges electrons with the electrode via the gold nanoparticles. Electroactive surface concentration of MP-11 at high scan rate is between 350+/-50 pmol cm(-2), which reflects a multilayer process. The formal potential (E degrees') of MP-11 in the gold nanoparticles-chitosan film was estimated to be -(267.7+/-2.9) mV at pH 7.0. The heterogeneous electron transfer rate constant (k(s)) starts at 1.21 s(-1) and levels off at 6.45 s(-1) in the scan rate range from 0.1 to 2.0 V s(-1). Oxidation and reduction of MP-11 by hydrogen peroxide and superoxide, respectively have been coupled to the direct electron transfer of MP-11.
KW  - Microperoxidase
KW  - Direct electron transfer
KW  - Nanoparticles
KW  - Hydrogen peroxide
KW  - Superoxide
KW  - Bioelectrocatalysis
Y1  - 2011
U6  - https://doi.org/10.1002/elan.201000535
SN  - 1040-0397
VL  - 23
IS  - 3
SP  - 611
EP  - 618
PB  - Wiley-Blackwell
CY  - Malden
ER  - 
TY  - JOUR
A1  - Wu, Yunhua
A1  - Wollenberger, Ursula
A1  - Hofrichter, Martin
A1  - Ullrich, Rene
A1  - Scheibner, Katrin
A1  - Scheller, Frieder W.
T1  - Direct electron transfer of Agrocybe aegerita peroxygenase at electrodes modified with chitosan-capped Au nanoparticles and its bioelectrocatalysis to aniline
JF  - Sensors and actuators : B, Chemical
N2  - Three different sizes of chitosan-capped Au nanoparticles were synthesized and were used to incorporate Agrocybe aegerita peroxygenase (AaeAPO) onto the surface of glassy carbon electrode. The direct electron transfer of AaeAPO was achieved in all films. The highest amount of electroactive enzyme and highest electron transfer rate constant k(s) of AaeAPO were obtained in the film with the smallest size of chitosan-capped Au nanoparticles.
 In anaerobic solutions, quasi-reversible oxidation and reduction are obtained with a formal potential of -0.280V vs. Ag/AgCl 1 M KCl in 100 mM (pH 7.0) PBS at scan rate of 1 V s(-1). Bioelectrocatalytic reduction currents can be obtained with the AaeAPO-modified electrode on addition of hydrogen peroxide. This reaction was suppressed when sodium azide, an inhibitor of AaeAPO, was present. Furthermore, the peroxide-dependent conversion of aniline was characterized and it was found that a polymer product via p-aminophenol is formed. And the AaeAPO biosensor was applied to determine aniline and p-aminophenol.
KW  - Agrocybe aegerita peroxygenase
KW  - Au nanoparticles
KW  - Direct electron transfer
KW  - Aniline biosensor
KW  - Bioelectrocatalysis
Y1  - 2011
U6  - https://doi.org/10.1016/j.snb.2011.09.090
SN  - 0925-4005
VL  - 160
IS  - 1
SP  - 1419
EP  - 1426
PB  - Elsevier
CY  - Lausanne
ER  -