Synthesis Of Nano-metal Colloids And Study Of Their SERS Activity

Surface-enhanced Raman scattering (SERS) is a unique surface optical phenomenon for that Raman signals of the molecules adsorbed on some metal surface can be enhanced by the factor of several millions. Surface-enhanced Raman spectroscopy shows high sensitivity for detecting the molecules adsorbed on the surface of the metals in sub- and monomolecular layers, and presents plentiful surface information of the molecular structure. Therefore, the spectroscopy has been widely used in some scientific and technical fields in recent years, such as chemistry, biology, surface science, qualitative and quantitative analysis, etc. With the development of the research, SERS is gradually become one of the research methods for the rising monomolecular science. The appropriate substrate is the premises to obtain favorable surface enhancement. Metal colloids are widely used as substrates for their low cost, simple preparation and favorable enhancement. In this thesis, we develop a series of correlative research and it is following as:1. Influence of variety of reducer agents,dosage and protecting agent on the size and distribution of colloidal silver particles were investigated. Then the size and distribution of the silver particles were determined by UV-vis spectroscopy and TEM, the results indicate that the size of colloidal silver particles was between 10nm and 100nm, the figure of colloidal silver particles were roundness including a few of club-shaped. By using pyridine and crystal violet as the probe molecules, SERS studies were performed, then we can get comparably simple, easy and active substrate in Surface-enhanced Raman scattering (SERS).2. The change current of Raman signals of crystal violet at the separate addition of nitric acid and hydrochloric acid was studied, and the results indicate that the effects of nitric acid and hydrochloric acid were consistent by and large, whereas the Raman signals of crystal violet were better with the presence of hydrochloric acid. Furthermore, the detecting limit of crystal violet and the adsorbing mechanism of crystal violet and colloidal silver particles were studied as hydrochloric acid was in existence.3. Silver colloids were labeled with Raman reporter molecules such as crystal violet to form surface-enhanced Raman scattering (SERS) reporter-labeled silver colloids. Firstly, antibody goat anti-rat was adsorbed onto the reporter-labeled silver colloids to form reporter-labeled immunosilver colloids in appropriate condition. Secondly, the glass slide which was assembled silver nanoparticles was coated with antibody and selectively adsorbed antigen rat IgG to form antibody-antigen couple, and the SERS reporter-labeled immunosilver colloids were modified onto the couple in a glass slide with silver nanoparticles adsorbing"antibody/antigen/ reporter-labeled immunosilver colloids"to form sandwich-type complex through the specific adsorption between antibody and antigen. The selective interaction between antibody and antigen can be read out by the labeling molecules.