Three techniques were compared for lowering the limit of detection (LOD) of the lateral flow immunoassay (LFIA) of the receptor-binding domain of severe acute respiratory syndrome-related coronavirus 2 (SARS-CoV-2) based on the post-assay in situ enlargement of Au nanoparticles (Au NPs) on a test strip. Silver enhancement (growth of a silver layer over Au NPs—Au@Ag NPs) and gold enhancement (growth of a gold layer over Au NPs) techniques and the novel technique of galvanic replacement of Ag by Au in Au@Ag NPs causing the formation of Au@Ag-Au NPs were performed. All the enhancements were performed on-site after completion of the conventional LFIA and maintained equipment-free assay. The assays demonstrated lowering of LODs in the following rows: 488 pg/mL (conventional LFIA with Au NPs), 61 pg/mL (silver enhancement), 8 pg/mL (galvanic replacement), and 1 pg/mL (gold enhancement). Using gold enhancement as the optimal technique, the maximal dilution of inactivated SARS-CoV-2-containing samples increased 500 times. The developed LFIA provided highly sensitive and rapid (8 min) point-of-need testing.
【저자키워드】 immunochromatography, coronavirus, Spike protein, point-of-care testing, Receptor-binding domain, antigen test, limit of detection, silver enhancement, gold enhancement, galvanic replacement, 【초록키워드】 SARS-CoV-2, lateral flow immunoassay, LFIA, silver, inactivated, Dilution, growth, performed, provided, demonstrated, the receptor-binding domain, 【제목키워드】 SARS-CoV-2, nanoparticle, gold, sensitive, Flow, Comparative, technique, Lateral,