Biocompatibility study of protein capped and uncapped silver nanoparticles on human hemoglobin

Abstract

The interactions of human hemoglobin with protein capped silver nanoparticles and bare silver nanoparticles were studied to understand fundamental perspectives about the biocompatibility of protein capped silver nanoparticles compared with bare silver nanoparticles. Bare silver (Ag) nanoparticles (NPs) were prepared by the chemical reduction method. High resolution transmission electron microscopy (HRTEM) analysis along with absorption at ~390 nm indicated the formation of bare Ag NPs. Protein coated Ag NPs were prepared by a green synthesis method. Absorption at ~440 nm along with ~280 nm indicated the formation of protein coated Ag NPs. The biocompatibility of the above mentioned Ag NPs was studied by interaction with human hemoglobin (Hb) protein. In presence of bare Ag NPs, the Soret band of Hb was red shifted. This revealed the distortion of iron from the heme pockets of Hb. Also, the fluorescence peak of Hb was quenched and red shifted which indicated that Hb became unfolded in the presence of bare Ag NPs. No red shift of the absorption of Soret, along with no shift and quenching of the fluorescence peak of Hb were observed in the presence of protein coated Ag NPs. A hemolysis assay suggested that protein coated Ag NPs were more biocompatible than bare one.