Probing the Interaction of Human Serum Albumin with Ciprofloxacin in the Presence of Silver Nanoparticles of Three Sizes: Multispectroscopic and ζ Potential Investigation

The binding of ciprofloxacin to human serum albumin (HSA) in the presence and absence of silver nanoparticles of three sizes was investigated for the first time. For this purpose fluorescence spectroscopy, circular dichroism, UV-vis spectroscopy, and zeta potential techniques were employed under physiological conditions. The titration results indicated that ciprofloxacin quenched the fluorescence intensity, of HSA through a static mechanism, but in the presence of Ag nanopartides of sizes I and II there were two different kinds of interaction behavior. Results of circular dichroism indicated that the secondary structure of HSA was modified with increasing ciprofloxacin concentration. A comparison between resonance light scattering of binary and ternary systems allowed us to estimate the effect of silver nanoparticles on the initial formation and aggregation of ciprofloxacin with HSA. The zeta-potential results suggested induced conformational changes on HSA, thus confirming the experimental and theoretical results.