Amplifying visible signals in lateral flow assays using integrated nanoelectrokinetics

Abstract

In this study, we developed a tangential nanoelectrokinetic force-enhanced lateral flow assay by integrating a Nafion-cellulose nanofibrils hybrid gel to improve conventional lateral flow assay performance without external instrumentation. Our assay was designed by embedding the Nafion-cellulose nanofibrils gel beneath the test line, generating a tangential nanoelectrokinetic force that enhances the migration and accumulation of antigen-AuNP probe complexes within the visible depth of the nitrocellulose surface. The proposed assay exhibited a 32.5-fold improvement in the limit of detection for COVID-19 nucleocapsid protein, achieving a 0.24 ng/mL. Clinical trials demonstrated 100% sensitivity and 100% specificity, far surpassing the performance of conventional lateral flow assays, which typically achieve 66.7 % sensitivity and 100 % specificity. Our assay also demonstrated high selectivity, with no cross-reactivity against other respiratory pathogens such as respiratory syncytial virus A, respiratory syncytial virus B, OC43 (COVID), influenza A, and influenza B, making it a robust and cost-effective solution for point-of-care diagnostics, particularly in resource-limited settings.