COVID-19 RAPID DETECTION THROUGH IMMUNODOMINANT PEPTIDE-BASED BIOSENSORS

COVID-19, caused by the SARS-CoV-2 virus, is highly transmissible, making rapid diagnostic tests essential, though viral mutations have affected their accuracy. Recent studies have targeted immunodominant epitopes in the RBD region, focusing on peptides that recognize IgG and IgA binding sites.¹ Notably, peptide P44 has shown high reactivity and is positioned in a mutation hotspot across several variants, leading to its selection for biosensor construction with SERS and electrochemical methods. Gold nanoparticles (AuNPs) of 30 nm were synthesized by the Turkevich method and functionalized with both P44-WT (wild-type) and its mutant form, P44-P1 (Gamma variant), stabilized by 4-mercaptobenzoic acid (MBA) to ensure controlled size, shape, and stability. Functionalization was confirmed by UV-Vis and DLS. SERS analysis, processed with PLS-DA, achieved 100% sensitivity and 90% specificity (n=104). Replicating the SERS platform on glassy carbon electrodes, electrochemical tests confirmed peptide-antibody interactions, with detection limits of 0.43 ng/mL for P44-WT and 0.98 ng/mL for P44-P1. Using sera from convalescent COVID-19 patients confirmed by ELISA, the assay demonstrated effective discrimination even with minor viral mutations. This promising methodology for SARS-CoV-2 antibody detection also shows potential for adaptation to other diseases by selecting suitable antibody-targeting peptides.