Quercetin-functionalized silver nanoparticles as a selective colorimetric sensor of Hg2+ in water and studies on interactions between the nanoparticles and bovine serum albumin

Abstract

Quercetin-functionalized silver nanoparticles (QC-AgNPs) were synthesized using quercetin as a reducing and stabilizing agent. UV-Vis and FTIR spectroscopy along with transmission electron microscopy (TEM) were used to confirm the fabrication of the functional nanoparticles. The QC-AgNPs demonstrated remarkable sensitivity and selectivity in the detection of Hg²⁺ in water. The probe also exhibited strong anti-interference performance against other metal ions. The detection limit (LOD) was 0.2 µM, indicating its potential use in the environmental sensing of Hg²⁺. Furthermore, to explore the potential of QC-AgNPs in the biosensing of Hg²⁺, the biodistribution of the nanoparticles was checked by studying their interactions with bovine serum albumin (BSA), a model carrier protein. Interactions between BSA and QC-AgNPs were explored using UV-Vis, steady-state, time-resolved and synchronous fluorescence spectroscopy. QC-AgNPs caused static quenching of tryptophan fluorescence of BSA with a quenching constant on the order of 10⁸ M⁻¹. The thermodynamic parameters (ΔH and ΔS) suggested predominant involvement of hydrophobic interactions in the binding process of nanoparticles with BSA.