Interaction of CTAB capped gold@iron bimetallic nanomaterials with bovine serum albumin: A multi-technique approach

Abstract

Multi-spectroscopic approaches were used for the investigation of bovine serum albumin (BSA) interaction with gold@iron bimetallic nanoparticles (BNPs). UV–visible spectra showed that absorbance of pure BSA increases with increasing BNPs concentration. The BSA fluorescence intensity decreased in presence of BNPs, which induced by the change of microenvironment of tryptophan moiety of protein. The distance between donor and acceptor was determined with surface energy transfer method. The apparent binding constant was calculated with Benesi-Hildebrand plot at 298 K. The bimolecular rate of quenching process (kq), Stern-Volmer constant (KSV), and number of binding sites (K) were estimated by using Stern-Volmer equation and found to be KSV = 9.0 × 103 L/mol, kq = 9.0 × 1010 L/mol/s, logK = 5.35 and KSV = 6.0 × 103 L/mol, kq = 6.0 × 1010 L/mol/s, logK = 7.4, respectively, for gold@iron and iron@gold. Analysis suggests that the outer iron metal of gold@iron core-shell nanoparticles is attached strongly with ionized functional groups of BSA in comparison to outer gold metal of iron@gold. The thermodynamic parameters (ΔG0 = −30.4 kJ/mol, ΔH0 = 40.3 kJ/mol, ΔS0 = 237.2 J/K/mol, and ΔG0 = −37.2 kJ/mol, ΔH0 = 34.7 kJ/mol, ΔS0 = 235.2 J/K/mol) were estimated using the Van't Hoff equation for gold@iron and iron@gold, respectively, and discussed.