A capacitive immunosensor for tetracycline estimation using antibody modified polytyramine-alkanethiol ultra-thin film on gold

Abstract

A Polytyramine-alkanethiol based electrochemical capacitive immunosensor was developed for tetracycline (TC) antibiotic detection in water. Tyramine (TA) monomer was electropolymerized to get an insulating ultrathin polytyramine (PTA) film on the gold-coated silicon electrode (AuE). The PTA coated AuEs were incubated in 1-Dodecanethiol to get thiol filled polymer-coated electrodes. This process of thiolation filled the pinholes of the polymer surface and enhanced the insulation of the polymer electrode, suited for capacitive sensor development. The thiolated polymer electrodes were modified with polyclonal antibodies against TC to get TC immunosensor (TCI). The prepared TCI was characterized at various steps of fabrication. The surface characterization was performed by using an atomic force microscope (AFM). The electrochemical characterizations were performed by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) technique. Further, the EIS measurements were carried out to measure the capacitance change of TCI in the presence of TC in matrix-matched water samples. The fabricated TCI exhibited linearity in 1 to 200 μgL−1 range for TC, with a limit of detection 0.01 μgL−1. Further, the fabricated TCI exhibited good selectivity towards TC with recovery from 96 to 102% in spiked water samples. Results indicate the possible application of developed immunosensor for TC estimation in water samples.