Self-assembling gold nanoparticles on thiol-functionalized poly(styrene- co-acrylic acid) nanospheres for fabrication of a mediatorless biosensor

Abstract

A novel strategy to construct a sensitive mediatorless sensor of H 2O 2 was described. At first, a cleaned gold electrode was immersed in thiol-functionalized poly(styrene- co-acrylic acid) (St- co-AA) nanosphere latex prepared by emulsifier-free emulsion polymerization St with AA and function with dithioglycol to assemble the nanospheres, then gold nanoparticles were chemisorbed onto the thiol groups and formed monolayers on the surface of poly(St- co-AA) nanospheres. Finally, horseradish peroxidase (HRP) was immobilized on the surface of the gold nanoparticles. The sensor displayed an excellent electrocatalytical response to reduction of H 2O 2 without the aid of an electron mediator. The biosensor showed a linear range of 8.0 μmol L −1–7.0 mmol L −1 with a detection limit of 4.0 μmol L −1. The biosensor retained more than 97.8% of its original activity after 60 days’ storage. Moreover, the studied biosensor exhibited good current reproducibility and good fabrication reproducibility.