Electrochemical Study of Horseradish Peroxidase Biosensor Based on Functionalised Magnetic Beads and Polypyrrole Film

摘要

Devices based on nanomaterials are emerging as a powerful and general class of ultrasensitive sensors for the direct detection of biological and chemical species. In this work, we present a two innovative way to immobilize a horseradish peroxidase (HRP) for the detection of hydrogen peroxide (H_2O_2). The strong avidin-biotin affinity is used to stack up successive monomolecular layers of horseradish peroxidase on gold electrodes. The first sensor was based on a monolayer of magnetic particles coated with streptavidin enabling after reaction with biotin the deposition of horseradish peroxidase conjugated streptavidin, formed on a gold electrode after application of a magnetic field. The second sensor was based on same magnetic particles with HRP entrapment during electrochemical deposition of polypyrrole. The cyclic voltammetry and amperometry techniques were used to monitor biosensor building-up process. The current response of the biosensors is dependent on the nature of the layer and the concentration of H_2O_2. The results show that the sensor based on polypyrrole with magnetic particles/horseradish peroxidase has a higher sensitivity (2.3 μA/mM) than the sensor based on magnetic particles/horseradish peroxidase (1.7 μA/mM) due to conductive properties of polypyrrole.