Electrochemical Immunosensor Based on Polythionine/Gold Nanoparticles for the Determination of Aflatoxin B1

• Main Authors: Joseph H.O. Owino, Nicolette Hendricks, Omotayo A. Arotiba, Everlyne A. Songa, Nazeem Jahed, Tesfaye T. Waryo, Emmanuel I. Iwuoha, Priscilla G .L. Baker, Rachel F. Ngece
• Format: Article
• Language: English
• Published: MDPI AG 2008-12-01
• Series: Sensors
• Subjects: Immunosensor; Gold nanoparticles; Aflatoxin B1; Polythionine; Horseradish peroxidise (HRP)
• Online Access: http://www.mdpi.com/1424-8220/8/12/8262/

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.