title: A hydrogen peroxide biosensor based on the direct electrochemistry of hemoglobin modified with quantum dots.
abstract: Direct electron transfer of hemoglobin modified with quantum dots (QDs) (CdS) has been performed at a normal graphite electrode. The response current is linearly dependent on the scan rate, indicating the direct electrochemistry of hemoglobin in that case is a surface-controlled electrode process. UV-vis spectra suggest that the conformation of hemoglobin modified with CdS is little different from that of hemoglobin alone, and the conformation changes reversibly in the pH range 3.0-10.0. The hemoglobin in a QD film can retain its bioactivity and the modified electrode can work as a hydrogen peroxide biosensor because of its peroxidase-like activity. This biosensor shows an excellent response to the reduction of H2O2 without the aid of an electron mediator. The catalytic current shows a linear dependence on the concentration of H2O2 in the range 5x10(-7)-3x10(-4) M with a detection limit of 6x10(-8) M. The response shows Michaelis-Menten behavior at higher H2O2 concentrations and the apparent Michaelis-Menten constant is estimated to be 112 microM.
authors.affiliation: College of Chemistry and Molecular Sciences, Wuhan University, Wuhan, 430072, People's Republic of China.
authors.forename: Yanxia
authors.initials: Y
authors.lastname: Xu
authors.forename: Jiangong
authors.initials: J
authors.lastname: Liang
authors.forename: Chengguo
authors.initials: C
authors.lastname: Hu
authors.forename: Fang
authors.initials: F
authors.lastname: Wang
authors.forename: Shengshui
authors.initials: S
authors.lastname: Hu
authors.forename: Zhike
authors.initials: Z
authors.lastname: He
mesh_terms: D015374:Biosensing Techniques / Q000379:methods*; D019187:Cadmium Compounds / Q000737:chemistry; D004563:Electrochemistry / Q000379:methods*; D004566:Electrodes; D005465:Fluorocarbon Polymers / Q000737:chemistry; D006454:Hemoglobins / Q000737:chemistry*; D006861:Hydrogen Peroxide / Q000032:analysis*; D006863:Hydrogen-Ion Concentration; D011487:Protein Conformation; D045663:Quantum Dots; D013056:Spectrophotometry, Ultraviolet; D013440:Sulfides / Q000737:chemistry
chemical_list: D019187:Cadmium Compounds; D005465:Fluorocarbon Polymers; D006454:Hemoglobins; D013440:Sulfides; C034939:cadmium sulfide; C040402:perfluorosulfonic acid; D006861:Hydrogen Peroxide