Electrochemical immunosensor based on PEG capped iron oxide nanoparticles

In this study, we have synthesized polyethylene glycol (PEG) capped iron oxide (Fe3O4) nanoparticles by chemical co-precipitation method. These PEG-Fe3O4 NPs and bare Fe3O4 NPs have been characterized using different techniques such as X-ray diffraction, transmission electron microscope, dynamic light scattering, Fourier transform infra-red spectroscopy, and electrophoresis technique. These PEG-Fe3O4 NPs were deposited onto indium tin oxide (ITO) coated glass substrate by electrophoretic deposition technique and further functionalized with the monoclonal antibodies (Ab) specific to Vibrio cholerae toxin and bovine serum albumin (BSA) using EDC-NHS chemistry. The functionalization of PEG-Fe3O4/ITO electrode with Ab and BSA confirmed, by a change in IR spectra. The electrochemical studies revealed that the PEG-Fe3O4/ITO electrode provides heterogeneous electron transfer rate as 0.342 s− 1, higher active surface area of 1.5 mm2 and provide excellent microenvironment for the entrapment of Ab and BSA. This BSA/Ab/PEG-Fe3O4/ITO immunoelectrode provides excellent sensitivity (99.6 Ω /ng 1 mL− 1 cm− 2) and low detection limit (0.5 ng mL− 1) as compared to other capping agents.