An electrochemical immunosensor for ultrasensitive detection of HBsAg based on platinum nanoparticles loaded on natural montmorillonite

Abstract

A sensitive and facile electrochemical immunosensor for ultrasensitive detection of hepatitis B surface antigen (HBsAg) was designed, which was based on platinum nanoparticle decorated amino silane functionalized montmorillonite (Pt–NH₂–MMT). As it is a luminosilicate clay mineral, the advantages of montmorillonite (MMT), such as a large specific surface area, good adsorption/ion exchange capacity and innocuousness, endow Pt–NH₂–MMT with better sensing performance. The platinum nanoparticles (Pt NPs) also play an important role due to their good biological compatibility, electron transport rate and catalytic activity. Pt NPs and the available amine group of second HBsAg-antibody could be bound strongly to each other. And the covalent bond between NH₂–MMT and the carboxyl group of primary HBsAg-antibody could be formed by the activation of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide/N-hydroxysuccinimide. Under optimal conditions, the Pt–NH₂–MMT showed high electrocatalytic activity toward hydrogen peroxide reduction. Under optimal conditions, the immunosensor showed a wide linear response to HBsAg ranging from 0.5 pg mL⁻¹ to 20 ng mL⁻¹ with a low detection limit of 2.0 × 10⁻⁴ ng mL⁻¹. The designed immunosensor displayed high sensitivity, stability and reproducibility for the analysis of HBsAg.