The Research Of Optical Properties Based On Au Nanoshell Materials And Loading PEGFP-C1 Plasmid

With the development of nanotechnology, multifunctional nanomaterials have drawn more and more attention in the fields of biology and medicine. The physicochemical properties of functional nanomaterials may provide platform for studying the interaction of the biological system. However, the application of nanomaterials in biomaterial interaction has many challenges. For example, the mechanism of the interaction between nanomaterials and the biological molecules is still not understood comprehensively, and how to understand their interaction by effective methods. These questions have become the focus of the study. The nanocomposite material which is consisted of dielectric nuclear and noble metal shell becomes a new biological function material. These materials have large scattering cross section, which could show obvious surface enhanced Raman spectroscopy(SERS) effect. The binding site of the biomolecule and nanomaterial can be determined by the SERS spectra. Above nanocomposite materials also exhibit good biocompatible properties by the modification of different surface ligands, which may be applied in biodetection or biocarrier. The interaction question between nanoparticles and biological molecules may be answered by using these gold nanoshells as SERS substrate.Based on above, this thesis mainly focused on the preparation of high SERS effect of Au/Ag alloy shell nanomaterials, and discussed the mechanism problems of biological molecules with the gold shell materials. So the concrete contents are as follows:1. By changing the relative proportion of gold and silver source, we prepared the controllable morphology of nanocomposite materials: Ag and Au alloy nanoparticles coated silica nanospheres. SERS detection of the p-aminothiophenol with Au/Ag alloy shell as substrate is experimented. Through analysis of Raman spectra, it was found that the SERS activity of Au/Ag alloy shell composites was stronger than that of gold shell materials. The Au/Ag alloy shell composite materials are a kind of substrate materials that have biological compatibility and high active SERS.2. To make the core/shell nanocomposite materials couple with the plasmid, PEI and PEG as ligands modified the surface of gold nanoshell materials, respectively. By studying the effect of the reaction conditions on the surface modification of the gold shell nanomaterials, it was found that p H in solution had great effect on surface modification of ligand. At higher p H(above 9), the PEI-Au nanocomposite showed positive surface potential. Plasmid p EGFP-C1 is of negative potential in the same condition. So PEI-Au composite materials could complex with plasmid p EGFP-C1 under this condition. Gel retardation assay was performed subsequently on complexes formed with a p DNA, namely, p EGFP-C1 and PEI-Au composite materials, prepared at varying charge ratios, so as to identify the DNA-binding abilities of composite materials. From the study described above, it was demonstrated that PEI-Au composite materials could complex with DNA efficiently.