title: Probing traces of hydrogen peroxide by use of a biosensor based on mediator-free DNA and horseradish peroxidase immobilized on silver nanoparticles.
abstract: A new electrochemical biosensor for determination of hydrogen peroxide (H(2)O(2)) has been developed by immobilizing horseradish peroxidase (HRP) on silver colloids (nanosilver) and use of a DNA-functionalized interface. In the presence of the DNA and the nanosilver the immobilized HRP gives a pair of well-defined redox peaks with an electron-transfer rate constant of 3.27 +/- 0.91 s(-1) in pH 7.0 PBS. The presence of DNA also provides a biocompatible microenvironment for enzyme molecules, greatly amplifies the amount of HRP molecules immobilized on the electrode surface, and improves the sensitivity of the biosensor. Under optimum conditions the biosensor has electrocatalytic activity in the reduction of hydrogen peroxide with linear dependence on H(2)O(2) concentration in the range 1.5 x 10(-6) to 2.0 x 10(-3) mol L(-1); the detection limit is 5.0 x 10(-7) mol L(-1) at a signal-to-noise ratio of 3. The K(app)(m) value of HRP in the composite membrane was found to be 1.62 mmol L(-1). These results suggest that the properties of the complex film, with its bioelectrochemical catalytic activity, could make it useful for development of bioelectronic devices and for investigation of protein electrochemistry at functional interfaces.
authors.affiliation: Chongqing Key Laboratory of Analytical Chemistry, College of Chemistry and Chemical Engineering, Southwest University, Chongqing, 400715, China.
authors.forename: Fuchuang
authors.initials: F
authors.lastname: Wang
authors.forename: Ruo
authors.initials: R
authors.lastname: Yuan
authors.forename: Yaqin
authors.initials: Y
authors.lastname: Chai
authors.forename: Dianping
authors.initials: D
authors.lastname: Tang
mesh_terms: D015374:Biosensing Techniques / Q000379:methods*; D004247:DNA; D004563:Electrochemistry; D004800:Enzymes, Immobilized; D006735:Horseradish Peroxidase; D006861:Hydrogen Peroxide / Q000032:analysis*; D053758:Nanoparticles; D010084:Oxidation-Reduction; D012834:Silver
chemical_list: D004800:Enzymes, Immobilized; D012834:Silver; D004247:DNA; D006861:Hydrogen Peroxide; D006735:Horseradish Peroxidase