Gold nanoparticles-decorated amine-terminated poly(amidoamine) dendrimer for sensitive electrochemical immunoassay of brevetoxins in food samples

Abstract

A sensitive electrochemical immunosensor for the fast screening of brevetoxin B (BTX-2) in food samples was developed by means of immobilizing BTX-2–bovine serum albumin conjugate (BTX-2–BSA) on the gold nanoparticles-decorated amine-terminated poly(amidoamine) dendrimers (AuNP–PAADs). The presence of gold nanoparticles greatly improved the conductivity of the PAADs, and three-dimensional PAADs increased the surface coverage of the biomolecules on the electrode. Under optimal conditions, three types of immunosensor, i.e. with AuNPs, PAADs, or AuNP–PAADs, were used for the determination of BTX-2 in a competitive-type immunoassay format using horseradish peroxidase-labeled anti-BTX antibodies (HRP– anti-BTX-2) as trace in the H 2O 2– o-phenylenediamine ( o-PD) system. A low detection limit (LOD) of 0.01 ng/mL and a wide dynamic working linear range of 0.03–8 ng/mL BTX-2 using AuNP–PAADs as matrices were obtained in comparison with those of only using AuNP or PAADs. Intra-batch assay precision was substantially improved by resorting to the AuNP–PAADs manifold. The proposed method features unbiased identification of negative (blank) and positive samples. No significant differences were encountered in the analysis of the spiking real samples between the electrochemical immunosensor and liquid chromatography for the determination of BTX-2. Importantly, this method provided a biocompatible immobilization and a promising immunosensing platform for analytes with small molecules in the analysis and detection of food safety.