SERS/photothermal-based dual-modal lateral flow immunoassays for sensitive and simultaneous antigen detection of respiratory viral infections

Lateral flow immunoassay (LFIA) is one of the most common analytical platforms for point-of-care testing (POCT), which is capable of large-scale primary screening and home self-testing of infectious diseases. However, the sensitivity of conventional AuNPs-based LFIA is relatively low and more prone to false negatives. Herein, we report a novel LFIA based on gold-core-silver-shell bimetallic nanoparticles (Au4-ATP@Ag NPs) emitting Surface -enhanced Raman scatting (SERS) and Photothermal (PT) effect, named SERS/PT-based dual-modal LFIA (SERS/ PT-dmLFIA), for the antigen detection of infectious diseases pathogens, which displayed an excellent perfor-mance. For influenza A virus (IAV), influenza B virus (IBV), and Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) N protein detection, the limit of detections (LoD) with Raman as signal were 31.25, 93.75, and 31.25 pg mL-1 respectively, and the LoDs with temperature difference (& UDelta;T) as signal were as low as 15.63, 187.5, and 15.63 pg mL-1 respectively, which were over 4-fold more sensitive than visual-based LFIA. The proposed SERS/PT-dmLFIA was used for detecting virus antigen in pharyngeal swabs and showed ideal coincidence rate of over 95% compared to the commercialized assays. In addition, we explored the development of multiplex SERS/ PT-dmLFIA that can detect IAV, IBV, and SARS-CoV-2 antigens simultaneously without cross reactivity. Overall, the SERS/PT-dmLFIA for antigen detection not only exhibits high sensitivity, accuracy and specificity, but also have characteristics of rapidity and simplicity, which holds high potential for rapid diagnosis of infectious dis-eases in laboratory testing, mass screening, and home self-testing.

Automated summary

The study reports a novel lateral flow immunoassay (LFIA) based on gold-core-silver-shell bimetallic nanoparticles (Au4-ATP@Ag NPs) with surface-enhanced Raman scattering (SERS) and photothermal (PT) effects, named SERS/PT-based dual-modal LFIA (SERS/PT-dmLFIA). This method exhibited excellent performance for antigen detection of infectious diseases pathogens, with high sensitivity, accuracy, and specificity. It is rapid and simple, making it suitable for laboratory testing, mass screening, and home self-testing.