Synthesis And Study Of Core/Shell Composite Nanomaterials Coated By Gold

Core/shell composite nanomaterial is a new material relating to multiple subjects, such as Materials, Optics and Bio-engineering, etc. Through the chemical and physical effects, core/shell structure is formed by coating shell nanomaterials on the surface of corer nanomaterials. Compared with single materials, core/shell nanomaterials have much more characteristics and its significant research value and broad application prospects in optical devices, biological sensing as well as fluorescent probes are given more and more attention in scientific research. Taking SiO2 microsphere,fluorescence doped polystyrene microsphere and CdSe semiconductor nanocrystal respectively as the core, in this thesis, the synthesis of core/shell composite nanomaterials coated by gold are synthesized using different technology, and a systematic study is done on its application in fluorescent probes, biological sensing, etc. The main contents of the research are as follow:1. Croe/shell composite nanomaterials are produced by taking fluorescence doped polystyrene microsphere and CdSe semiconductor nanocrystal as the core, poly-L-histidihe(PLH) as the Au deposition template, and coating ultra slim gold shell on the surface of the core. As shown in the experimental results, ultra slim gold shell can be produced due to the introduction of PLH, it almost is 2-3nm in CdSe@Au sample. The space structure solves the problem of fluorescent quench. It can enhance more than 40%. In addition, according to the principle of Plasmon resonance, by controlling the thickness of shell, the Au surface Plasmon resonance peak can shift to near infrared band (about 822nm)2. With L-Cysteine(L-Cys) as the stabilizer, CdSe nanocrystal with different diameter and multi-function on the surface is produced using sol-gel method in water, and the study of the fluorescence probe of lysozyme is conducted. Experimental results show that the absorbance and fluorescence spectrum of semiconductor nanocrystals with different grain diameter can shift from 475nm to 580nm continuously, they have narrow Full Wave at Half Maximum(<50nm) and high differentiable, the optical performance is stable. Moreover, the introduction of L-Cys as the stabilizer allows the co-existence of-COOH and-NH2, which provide more choice for the preparation of core/shell materials and their biological application.3. The application of core/shell composite nanomaterials produced in the experiment, in fluorescent probes, biological sensing and the detecting of cellular immunity, are studied by surface functionalization. The Experiments show that the CdSe@Au sample is more sensitive than SiO2@Au made using traditionary method (about 6.4 times). In addition, the application of fluorescence detection for LNCaP cell and dual-modality imaging also prove the multifunctional of our new core/shell composite materials.