An aflatoxin B1 (AFB1) electrochemical immunosensor was developed by the
immobilisation of aflatoxin B1-bovine serum albumin (AFB1-BSA) conjugate on a
polythionine (PTH)/gold nanoparticles (AuNP)-modified glassy carbon electrode (GCE).
The surface of the AFB1-BSA conjugate was covered with horseradish peroxidase (HRP),
in order to prevent non-specific binding of the immunosensors with ions in the test
solution. The AFB1 immunosensor exhibited a quasi-reversible electrochemistry as
indicated by a cyclic voltammetric (CV) peak separation (ΔEp) value of 62 mV. The
experimental procedure for the detection of AFB1 involved the setting up of a competition
between free AFB1 and the immobilised AFB1-BSA conjugate for the binding sites of free
anti-aflatoxin B1 (anti-AFB1) antibody. The immunosensor’s differential pulse
voltammetry (DPV) responses (peak currents) decreased as the concentration of free AFB1
increased within a dynamic linear range (DLR) of 0.6 - 2.4 ng/mL AFB1 and a limit of
detection (LOD) of 0.07 ng/mL AFB1. This immunosensing procedure eliminates the need
for enzyme-labeled secondary antibodies normally used in conventional ELISA–based
immunosensors