A hydrogen peroxide biosensor based on nano-Au/PAMAM dendrimer/cystamine modified gold electrode

Horseradish peroxidase (HRT) to a nano-Au monolayer, which was supported by PAMAM dendrimer/cystamine modified gold electrode. The high affinity of PAMAM dendrimer for nano-Au with its amine groups was used to realize the role of nano-Au as an intermediator to retain the high bioactivity of HRP A hydrogen peroxide biosensor was fabricated based on the effective immobilization of the high bioactivity of HRP. In the presence of the hydroquinone mediator in the solution, the immobilized HRP exhibited excellent electrocatalytical response to the reduction of H2O2. The effects of various experimental variables were optimized. The resulting biosensor showed a linear response to H2O2 over a concentration range from 1 x 10(-5) to 2.5 x 10(-3) mol L-1 with a sensitivity of 0.53 A L mol(-1) cm(-2) and a detection limit of 2.0 mu mol L-1 based on a signal-to-noise ratio of 3. The apparent Michaelis-Menten constant (K-m(app)) of the biosensor was evaluated to be 0.52 mmol L-1. The biosensor exhibited high sensitivity and good stability and reproducibility. Performance of the biosensor was evaluated with respect to possible interferences and the application to real sample analysis. (c) 2004 Elsevier B.V. All rights reserved.