title: Direct electrochemistry of horseradish peroxidase immobilized on a colloid/cysteamine-modified gold electrode.
abstract: Direct electron transfer of immobilized horseradish peroxidase on gold colloid and its application as a biosensor were investigated by using electrochemical methods. The Au colloids were associated with a cysteamine monolayer on the gold electrode surface. A pair of redox peaks attributed to the direct redox reaction of horseradish peroxidase (HRP) were observed at the HRP/Au colloid/cysteamine-modified electrode in 0.1 M phosphate buffer (pH 7.0). The surface coverage of HRP immobilized on Au colloid was about 7.6 x 10(-10) mol/cm(2). The sensor displayed an excellent electrocatalytic response to the reduction of H(2)O(2) without the aid of an electron mediator. The calibration range of H(2)O(2) was 1. 4 microM to 9.2 mM with good linear relation from 1.4 microM to 2.8 mM. A detection limit of 0.58 microM was estimated at a signal-to-noise ratio of 3. The sensor showed good reproducibility for the determination of H(2)O(2). The variation coefficients were 3. 1 and 3.9% (n = 10) at 46 microM and 2.8 mM H(2)O(2), respectively. The response showed a Michaelis-Menten behavior at higher H(2)O(2) concentrations. The K(app)(M) value for the H(2)O(2) sensor was found to be 2.3 mM.
authors.affiliation: Department of Chemistry, State Key Laboratory of Coordination Chemistry, Nanjing University, Nanjing, 210093, People's Republic of China.
authors.forename: X
authors.initials: X
authors.lastname: Yi
authors.forename: J
authors.initials: J
authors.lastname: Huang-Xian
authors.forename: C
authors.initials: C
authors.lastname: Hong-Yuan
mesh_terms: D015374:Biosensing Techniques / Q000295:instrumentation*; D003102:Colloids; D003543:Cysteamine; D004563:Electrochemistry; D004566:Electrodes; D004579:Electron Transport; D004800:Enzymes, Immobilized; D006046:Gold; D006735:Horseradish Peroxidase / Q000378:metabolism*; D006861:Hydrogen Peroxide / Q000032:analysis*
chemical_list: D003102:Colloids; D004800:Enzymes, Immobilized; D003543:Cysteamine; D006046:Gold; D006861:Hydrogen Peroxide; D006735:Horseradish Peroxidase