Fabrication and Modeling of an Ultrasensitive Label Free Impedimetric Immunosensor for Aflatoxin B1 based on Protein A Self-assembly Modified Gold 3D Nanotube Electrode ensembles

Abstract

A novel label-free impedimetric immunosensor for the quantitative detection of aflatoxin B1 (AFB1) was developed based on orientated staphylococcus protein A (SPA) modified gold three dimensional nanotube ensembles (3DTNEEs) which consisted of gold nanotubes fabricated by combining the technologies of template synthesis and controlled chemical etching of track-etched polycarbonate membrane. The structure and morphology of 3DTNEEs were evaluated by scanning electron microscopy. The diffusion characteristic and local current distribution on 3DTNEEs were simulated via the COMSOL Multiphysics 4.4 simulative software. The SPA self-assembly modified 3DTNEEs (SPA/3DTNEEs) was assessed by X-ray photoelectron spectroscopy. Electrochemical impedance spectroscopy was employed to characterize the fabrication process and optimize working conditions. The model of the molecular recognition interface was constructed and analyzed. The detection limit of AFB1 was 1.0×10−12gmL−1 (S/N=3) with a linear AFB1 concentration range of 4.0×10−12 to 6.0×10−9gmL−1. The AFB1 recovery test in corn samples demonstrated one potential application of the immunosensor.