Fluorescence Nanosensor Based on Modified Sustainable Silica for Highly Sensitive Detection of Sars-Cov-2 Igg Antibody

COVID-19 continues to pose significant global health challenges, leading to continuous developments in detection, vaccination, and treatment strategies that require an accurate and rapid detection of severe acute respiratory syndrome coronavirus 2 immunoglobulin G (SARS-CoV-2 IgG) antibodies. Since its emergence in 2020, SARS-CoV-2 has undergone multiple mutations, leading to the development of new variants that necessitate updated vaccines and diagnostic methodologies. 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 (FSNP) synthesized via the sol-gel method and functionalized with rhodamine B as a fluorescence dye. Fourier-transform infrared (FTIR) analysis confirmed the successful immobilization of anti-IgG on the FSNP surface, as evidenced by 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 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 10-2 to 10-8 µg/mL and a limit of detection (LOD) of 5.3 fg/mL. This research highlights the potential of modified sustainable silica-based fluorescence nanosensors for advancing sensitive and rapid COVID-19 diagnostics.