Electrochemical lateral flow assay for SARS-CoV-2 IgG detection utilizing PEGylated gold-decorated Iron oxide nanoplatforms.

This study details the development of a highly sensitive electrochemical lateral flow assay (ELFA) for the detection of SARS-CoV-2 immunoglobulin G (IgG). The assay utilizes novel polyethylene glycol (PEG)-coated Fe₃O₄ nanoparticles decorated with gold (Fe₃O₄@PEG@Au) as electrochemical labels, integrated with custom-fabricated screen-printed electrodes (c-SPEs). The Fe₃O₄@PEG@Au nanoplatforms were synthesized hydrothermally and thoroughly characterized using techniques including Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDS), Fourier Transform Infrared Spectroscopy (FTIR), and Dynamic Light Scattering (DLS), confirming their successful formation and ferrocene carboxylic acid (Fc) conjugation. The optimized ELFA demonstrated sensitive and reliable IgG detection in buffer, with optimal performance achieved using sodium tetraborate. Crucially, the assay exhibited robust detection capabilities in complex human serum, particularly in diluted samples where matrix effects were minimized. Performance comparison with both commercial rapid lateral flow assays and the gold-standard ELISA method showed comparable results in human serum. This research establishes the significant promise of Fe₃O₄@PEG@Au nanoplatforms within electrochemical LFAs, offering a path toward rapid, sensitive, and robust point-of-care SARS-CoV-2 IgG diagnostics.