Interaction of Gold Nanoparticles with Common Human Blood Proteins
Silvia H. De Paoli Lacerda, Jung J. Park, Curtis W. Meuse, Denis Pristinski, Matthew Becker, Jack F. Douglas
Gold nanoparticles (NPs) provide a promising platform for diagnostics and therapy, as well as other biomedical applications. The recent literature, however, contains conflicting data regarding the cytotoxicity of NPs. We have thus performed an array of photophysical measurement to systematically investigate the interaction of gold NPs with common blood proteins in order to understand the physical basis of NP biological activity. In particular, absorbance, fluorescence quenching, circular dichroism, dynamic light scattering and electron microscopy were performed on water soluble gold nanoparticles in a diameter range from 5 nm to 100 nm in the presence of basic human blood proteins: albumin, fibrinogen, -globulin, histone and insulin. Our findings show that gold NPs strongly associate with essential human blood proteins, and that the binding association constant, as well as the extent of cooperativity of particle-protein binding, depend on particle size and the native protein structure. We also find the proteins to undergo conformational change upon association with the NPs and that the thickness of the adsorbed protein layer on the NP (bare particle size range < 50 nm) progressively increases with NP size, effects that have potential general importance for NP aggregation in biological media.