A novel electrochemical immunosensor for aflatoxin B1 based on Au nanoparticles-poly 4-aminobenzoic acid supported graphene

Abstract

In this work, 4-aminobenzoic acid (PABA) is used to reduce graphene oxide by means of epoxy ring opening reaction to obtain hybrid 4-aminobenzoic acid-reduced graphene oxide (PABA-r-GO) nanocomposites. Au3+ is reduced to Au nanoparticle (Au NPs) in the above-mentioned reaction solution under excessive PABA to form Au-poly PABA (PPABA)-r-GO nanohybrids. After that, it is dropped on a glassy carbon electrode surface where the carboxyl groups are used to covalently link aflatoxin B1 (AFB1) antibodies, and Au NPs simultaneously bond AFB1 antibodies in a synergistic reaction. In succession, bovine serum albumin is used to block nonspecific sites. Finally, an electrochemical immunosensor is constructed where Fe(CN)63−/4− is used to produce impedance signal. The obtained immunosensor exhibits good linear range from 0.01 to 1 ng mL−1 and 1 to 25 ng mL−1, and its detection limit is determined to be 0.001 ng mL−1 (S/N = 3). This immunosensor also exhibits satisfactory reproducibility, selectivity, and stability. Moreover, the immunosensor successfully detects AFB1 in vegetable oil samples.