Porous gold-nanoparticle-CaCO3 hybrid material:: Preparation, characterization, and application for horseradish peroxidase assembly and direct electrochemistry

Gold nanoparticles (AuNPs) were assembled oil the surface of porous calcium carbonate microspheres (CaCO3) in a neutral aqueous solution through electrostatic interaction. The resulting gold-nanoparticle-CaCO3 hybrid material (AuNP-CaCO3) was characterized and expected to offer a promising template for enzyme immobilization and biosensor fabrication because of its satisfying biocompatibility and improved properties. It was conjugated with horseradish peroxidase (HRP) to fabricate HRP-AuNP-CaCO3 bioconjugates, which were then embedded into a silica sol-gel matrix to construct a novel biosensor. Because of the synergic effect of CaCO3 microspheres and AuNPs, direct electron transfer of HRP was observed at this biosensor. The biosensor exhibited a fast amperometric response to H2O2, with a linear range of 4.0 x 10(-5) to 8.0 x 10(-3) mol/L. The detection limit was 1.0 x 10(-6) mol/L based on S/N = 3.