Development of a novel capacitance electrochemical biosensor based on silicon nitride for ochratoxin A detection

Abstract

We report in this paper about the development of a novel capacitance electrochemical biosensor based on silicon nitride substrate (Si3N4) combined with a new structure of mangnetic nanoparticles (MNPs). Si3N4 is highly stable as it was fabricated by a combination of several layers of Aluminum (Al), silicon p-doped (Si-p), silicon dioxide (SiO2) and silicon nitride (Si3N4). This structure (Si3N4/SiO2/Si-p/Al) has provided several advantages compared with other materials commonly used, and in particular in solid-state physics for electronic-based biosensors. The MNPs with terminated carboxylic acid were covalently bonded to Si3N4 through a Self-Assembled Monolayers (SAMs) of the silane-amine (3-Aminopropyl) triethoxysilane (APTES). Finally anti-ochratoxin A antibodies were immobilized on MNPs by amide bonding. Contact Angle measurements, Atomic Force Microscopy, Scanning Electron Microscopy and Fluorescence Microscopy characterizations were performed during the biofunctionalization of the biosensor surface. Electrochemical measurements were carried out using Mott-Schottky analysis for ochratoxin A detection. The biosensor was highly sensitive and specific for ochratoxin A antigens, with a limit of detection of 4.57 pM, when compared to other interferences ochratoxin B and aflatoxin G1. The measurements were highly stable and reproducible for detection and interferences. The proposed method is very promising for ochratoxin A detection of several agro-food industry applications.