Tryptophan capped gold-aryl nanoparticles for energy transfer study with SARS-CoV-2 spike proteins.

Current research on coronavirus 2 disease (SARS-CoV-2) has been focused on developing reliable gold nanomaterials and methods for the detection of viral spike protein (S-proteins). Here, we describe the fluorescence quenching of spike proteins in the presence of robust gold-aryl nanoparticles. The obtained results demonstrated a strong binding affinity between S-proteins and tryptophan immobilized on gold-carbon nanoparticles (Trp-AuNPs) based on the binding constant value of 11.098 M⁻¹. Förster non-radiative energy transfer (FRET) calculations showed an average binding distance of r = 3.06 nm and a critical energy transfer distance of R₀ = 2.5 nm. Time-resolved fluorescence studies of conjugated S-proteins onto Trp-AuNPs revealed a short fluorescence lifetime and dynamic quenching. [ABSTRACT FROM AUTHOR]