4-Fluoro-3-nitrophenyl grafted gold electrode based platform for label free electrochemical detection of interleukin-2 protein

A new platform based on 4-Fluoro-3-nitrophenyl (FNP) grafted gold disk electrode prepared via electrochemical reduction of 4-fluoro-3-nitrobenzene diazonium ion has been developed and utilized for biosensor fabrication. Anti-interleukin-2 (anti-IL2) antibody has been covalently immobilized onto FNP/Au surface and utilized for label free electrochemical impedance based detection of cytokine IL2. FNP acts as a bridge (cross-linker) between gold surface and anti-IL2, where fluoro group of FNP undergoes nucleophilic substitution by amino group of biomolecule and results in its covalent immobilization. The immobilization process and fabricated electrode have been characterized using contact angle (CA) measurements, cyclic voltammetry (CV) and electrochemical impedance (EIS) technique. CV studies show that FNP grafted surface provides conductive surface for anti-IL2 immobilization. The EIS response of studies as a function of IL2 concentrations exhibits a detection in linear range from 1 pg ml−1 to 10 ng ml−1 with minimum detectable concentration of 1 pg ml−1. The electrode has been found to be selective against other cytokine molecules.