Evaluation of a modified carbon micromesh electrode as a new substrate for electrochemical immunosensing

Abstract

Here we report a novel immunosensor platform technology based on self-assembled monolayer (SAM) of electrodeposited gold (Au) nanostructures with subsequent antibody attachment. Carbon cloth micro-fibres were employed for the first time as a working electrode in an immunosensor device. Uniform distribution of Au nanoparticles was achieved on the surface of microfibers with regulation of particle size and shape made possible via controlled scan rate during deposition from aqueous AuCl₄. The electrodes were successfully characterised using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA). Chemiluminescence detection confirmed successful attachment of anti-actin antibodies onto the modified conducting surface, allowing detection of various concentrations of the actin antigen (0.1–1 µg ml⁻¹). The binding of antigen to antibody was successfully measured using EIS in 1 mM K₃Fe(CN)₆/K₄Fe(CN)₆ as a redox probe, which allowed determination of charge transfer resistance (R_ct) changes upon binding. A linear increase in R_ct was observed with increasing concentration of antigen (actin). Therefore, we have clearly demonstrated that this new electrochemical immunosensor design is effective, and can be applied to the analysis of a clinically significant protein.