Synthesis Of GNP Array With Continuous Change Of Hydrophobicity And Its Interaction With Protein

Nanomaterials are materials with structure units at the nanoscale (1-100nm) in at least one dimension. Their unique physical and chemical properties have attracted widespread attention, especially in biomedicine field. Gold nanoparticles have been widely investigated and applied in nanomedicine. When introducing proper functional groups to the surface of nanomaterials, there will be a provement in the solubility and biocompatibility of nanomaterials and so laid the foundation for application in biomedcine. Protein is an important component of biological macromoleculars in live body and serves as the basis of life. The surface of biomaterials can be immediately covered by proteins when they contact in a biological medium. It may not only changethe structure and function of proteins, but also affect the biological activity of nanomaterials directly. Studies have shown that the physicochemical properties of nanoparticles (e.g size, surface chemistry) and the nature of the protein can affect the interaction between nanoparticles and protein. However, in the published studies, due to the various of functional groups and generally more than one property in change, these will lead to the results may be contributy by more than one factor which can not reflect the effects of single surface property. So it is improtant to create some nanoparticle arrays with continuous change of single surface property and discuss each property’s influence onnanoparticle-protein interaction. It is critical for the development of nanomedicine and nanotoxicology.This research consists of two parts:In the first part, we used sodium borohydride reduction method to create a gold nanoparticle (GNP) arrays with continuous change of hydrophobicity by adjusting the proportion of two functional ligands with different hydrophobicity. The GNP array was characterized by transmission electron microscopy(TEM), dynamic light scattering (DLS) technique and Zeta potential to. Cleaved ligands from GNPs with I2, and the amount of ligands on the surface of GNPs were quantificated by HPLC-MS. The hydrophobicity of GNPs were characterizated by octanol-water partition coefficient (logP). -We make the following conclusions by summarizing the results:All GNPs have similar size (5-8nm), DLS (150～300nm), Zeta potential (-10～-20mV) and total amount of two ligands. The result of octanol-water partition coefficient (logP) show films’ water contact angle declined, which suggested that their hydrophilicity was gradually raised.In the second part, we stduied the interaction of five GNP arrys with bovine serum albumin (BSA) by steady-state fluorescence spectrum. Five GNP arrays have been designed with continuous change of five different surface properties (surface charge density, hydrophobicity,π bond, H bond and stereochemistry), respectively.We draw conclusions from the results:All GNPs have the ability to quench the intrinsic fluorescence of BSA, and the quenching mechanism is static quenching. All GNPs have no additional effect on the comformation of BSA. The results show that large density of the surface charge, higher hydrophility, higer π bond density and higher H acceptor or donor are favorable to enhance the binding constant between GNPs and BSA. But the binding constant has no significant change when altered the surface stereochemistry of GNPs.