LAUSR

Abstract UV-visible and florescence spectroscopic methods have been applied to analyze the binding capabilities of Ag+ ions and AgNPs with bovine serum albumin (BSA). UV-visible studies revealed that BSA acted as a ligand towards both Ag+ and AgNPs, and provides potential site for coordination. BSA fluorescence was quenched significantly by the quenchers (Ag+ and AgNPs). The binding constant, quenching constant, quantum yield, and coordination sites were evaluated. The Ag+ ions has strong binding and quenching efficiency towards BSA than that of AgNPs. The distance between the tryptophan and acceptor decreases from 127 A to 72 A with Ag+ ions from 0.6 to 20.0 × 10-5 mol/L. The energy transfer from BSA to ligand (Ag+ ions and AgNPs) follows a surface energy transfer process with a 1/d4 distance dependence. This is found to be according to strong coordinating affinity of metal ions with structural unit of protein, which helps to understand the mechanism of bacterial cell death in presence of metal ions and/or metal NPs.