Janus Fe3O4-Au@Pt nanozymes based lateral flow assay for enhanced-sensitive colorimetric detection of influenza A virus

Abstract

The traditional colloidal gold-based lateral flow assay (LFA) is widely applied in point-of-care testing (POCT) for pathogens. However, its disadvantage of low sensitivity greatly limits its effectiveness in early detection. In this work, we developed an enhanced-sensitive colorimetric nucleic acid lateral flow assay (NALFA) based on Janus Fe3O4-Au@Pt nanoparticles (Fe3O4-Au@Pt NPs) for H1N1 influenza virus detection. Dumbbell-like heterodimer Fe3O4-Au@Pt NPs were prepared by a seed-mediated method, and their unique Janus structure endowed them with both good plasmonic property and high peroxidase-like activity. With the Fe3O4-Au@Pt NPs as NALFA signal labels, qualitative detection was achieved by observing the color change with the naked eyes, and quantitative results were obtained by measuring the gray values on test strips. Due to the strong peroxidase-like activity of Fe3O4-Au@Pt NPs, they could quickly catalyze 3,3′,5,5′-tetramethylbenzidine (TMB) to oxidize to the dark blue chelate (oxTMB), thus resulting in greatly enhanced color on the strips. The limit of detection (LOD) of NALFA reached as low as 50 pM, which was 20-fold lower than that of before catalysis. Therefore, the constructed Janus Fe3O4-Au@Pt NPs could effectively improve the performance of traditional colloidal gold LFA and provide a potential tool for the development of sensitive sensing platforms.