A fluorescence nanosensor based on modified sustainable silica for highly sensitive detection of the SARS-CoV-2 IgG antibody†

This study presents an innovative fluorescence nanosensor utilizing modified sustainable silica for the ultra-sensitive detection of SARS-CoV-2 IgG antibodies. The sensor employs fluorescent dye-doped silica nanoparticles (FSNPs) synthesized via the sol–gel method and functionalized with rhodamine B as a fluorescent dye. Fourier-transform infrared (FTIR) analysis confirmed the successful immobilization of anti-IgG on the FSNP surface, as evidenced by the characteristic amide I and II peaks at 1641 cm⁻¹ and 1530 cm⁻¹, respectively. Detection of SARS-CoV-2 IgG antibodies was achieved through the enhanced fluorescence intensity of FSNP-anti-IgG at 582 nm. Optimal detection conditions were established with a 15-minute incubation period, demonstrating a linear detection range from 10⁻⁸ to 10⁻² μg mL⁻¹ and a limit of detection (LOD) of 5.3 fg mL⁻¹. This research highlights the potential of modified sustainable silica-based fluorescence nanosensors, particularly those utilizing FSNP-anti IgG, for advancing sensitive, rapid, and cost-effective COVID-19 diagnostics, making them a viable option for pathogen detection in resource-limited settings.