Label-free piezoelectric immunosensor decorated with gold nanoparticles: Kinetic analysis and biosensing application

A label-free electrochemical quartz crystal microbalance (EQCM) based immunosensor using self-assembled monolayer of hexandithiol (HDT), cysteamine and 3D gold nanoparticles (AuNPs) was fabricated and utilized for aflatoxin 81 (AFB1, food mycotoxin) detection. The morphology, bonding and optimized experimental conditions of fabricated electrode and immunoelectrode were investigated by scanning electron microscopy (SEM), atomic force microscopy (AFM), Fourier transform infrared spectroscopy (FT-IR) and electrochemical quartz crystal microbalance cyclic voltammetry (EQCM-CV) techniques. This novel Cys/AuNPs/HDT/Au platform was utilized for covalent immobilization of aAFB1. The two linear ranges are observed under optimized experimental conditions i.e. 0.008-0.3 ngmL(-1) and 1-10 ngmL(-1) that can be used to estimate AFB1 with high sensitivity of 126 pAng(-1) mLcm(-2) and low detection limit of 8 pgmL(-1) using EQCM-CV. The label free AFB1 detection in noncompetitive mode with high sensitivity and wide linear range is assigned to the presence of antibodies and networking of 3D AuNPs on self assembled HDT monolayer. Attempts have also been made to utilize the immnunosensor for detection of AFB1 in spiked corn flakes samples for validating the observed results. (C) 2015 Elsevier B.V. All rights reserved.