Probing traces of hydrogen peroxide by use of a biosensor based on mediator-free DNA and horseradish peroxidase immobilized on silver nanoparticles |
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Authors: | Fuchuang Wang Ruo Yuan Yaqin Chai Dianping Tang |
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Institution: | (1) Chongqing Key Laboratory of Analytical Chemistry, College of Chemistry and Chemical Engineering, Southwest University, Chongqing, 400715, China |
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Abstract: | A new electrochemical biosensor for determination of hydrogen peroxide (H2O2) 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 H2O2 concentration in the range 1.5 × 10−6 to 2.0 × 10−3 mol L−1; the detection limit is 5.0 × 10−7 mol L−1 at a signal-to-noise ratio of 3. The 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. |
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Keywords: | Electrochemical biosensor DNA Hydrogen peroxide Silver nanoparticles |
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