Au nanoparticle modified GO/PEDOT-PSS based immunosensor probes for sensitive and selective detection of serum immunoglobulin g (IgG)

Abstract

In the present work, we have developed a cost effective, label free, sensitive and selective, capacitive immunosensor based on composites of conducting polymer PEDOT-PSS, graphene oxide (GO) and gold nanoparticles (AuNPs) deposited on ITO electrode. The composite electrode was fabricated by performing electrochemical polymerization of EDOT monomer in presence of PSS, keeping GO as dopant covered with chemically inert AuNPs. The composite electrode has been studied by using various structural characterization techniques to understand the improved composition and morphology. To investigate the electrochemical properties of modified electrodes Cyclic Voltammetry (CV) and Electrochemical Impedance Spectroscopy (EIS) were employed. New redox peaks and peak shifts in the CV of PEDOT-PSS indicated incorporation of GO and Au. Impedance data for all three electrodes was analyzed using a common equivalent circuit and suggested both kinetically and diffusion controlled processes. Specific interaction of antibody-analyte for all three electrodes was monitored directly via transient capacitance measurements at low and medium frequencies. Results showed that the AuNP/GO/PEDOT-PSS electrode is stronger mechanically and highly sensitive suggesting flexible sensor applications. With transient capacitance measurements, the proposed immunosensor exhibits high sensitivity in the range of 9–363 ng/mL with a detection limit of 49 ng/mL.