Enhanced Detection of SARS-CoV-2 Using Platinum-Decorated Poly(2-vinylpyridine) Nanoparticle-Based Lateral Flow Immunoassay

Background: Rapid and high-throughput diagnostic methods are essential for controlling the spread of infectious diseases, such as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Lateral flow immunoassay (LFIA) strips provide a cost-effective and user-friendly platform for point-of-care testing. However, the sensitivity of conventional LFIA kits is often limited by the performance of their detection probes. This study reports a highly sensitive LFIA strip for detecting the SARS-CoV-2 nucleocapsid (NP) protein using platinum-decorated poly(2-vinylpyridine) nanoparticles (Pt-P2VPs) as probes. Methods: Monoclonal antibodies against SARS-CoV-2 NP were conjugated with Pt-P2VPs and incorporated into LFIA strips. The test line was coated with anti-SARS-CoV-2 NP monoclonal antibody, and the control line with goat anti-mouse IgG. Recombinant proteins, viral strains, and nasopharyngeal swab specimens from patients were used to evaluate assay performance, with reverse transcription polymerase chain reaction (RT-PCR) as the reference standard. Diagnostic accuracy was assessed using nonparametric statistical tests. Results: Pt-P2VP-based LFIA strips enabled sensitive detection of recombinant NP and inactivated SARS-CoV-2, with minimal cross-reactivity. In 200 clinical specimens (100 PCR-negative and 100 PCR-positive), the assay achieved 74% sensitivity and 100% specificity, with strong correlation to viral RNA load. Compared with conventional LFIA kits, Pt-P2VP strips demonstrated superior sensitivity at lower viral loads. Conclusions: Pt-P2VPs represent a promising probe material for enhancing LFIA performance and may facilitate the development of rapid, sensitive, and scalable immunoassays for infectious disease diagnostics in biomedical applications.