Study The Surface-enhanced Raman Scattering Of Silica Film And Self-assembled Gold Nanoparticles Array

Surface-enhanced Raman scattering (SERS) depends not only on the particle size,shape, and spacing, but also on the nature of materials. SiO2is a nontoxic, highlystable, and biocompatible material that has been widely used in bioanalysis, However,SiO2does not support surface plasmons and shows no SERS activity. Therefore, it isdifficult to obtain spectral informations of species that are adsorbed at its surfaceusing SERS. In this thesis, we try to extend SERS to SERS-inactive SiO2usingborrowed SERS technique, our aim is to provide feasible spectral means that allowsacquiring structural informations of species with a molecule level from the surfaces ofSiO2and other non metal materials. In addition, to overcome the problems relatedwith poor spectral reproducibility of SERS, we used PEG to tune the interparticlespacing in the assembly of Au nanoparticles, i.e., the size of hot spot, and preparedthe SERS substrates of thin nanoparticle films, which show improved spectralreproducibility. The main results and conclusions are outlines as below.(1)(3-mercaptopropyl)trimethoxysilane (MPTS) was modified on the roughenedAu electrode, acquiring a dense MPTS modifying layer.(2) Using the dense MPTS layer as primer, ultrathin, pinhole-free SiO2filmswere successfully grown on the roughened Au electrode；the Au/SiO2overlayeredSERS substrates enable borrowed SERS to be realized on the surface of SiO2.(3) We used HS-PEG to modify the Au nanoparticles and investigated theirstability, reversibility, and preservation.(4) We found that concentration of PEG-modified Au nanoparticles easily makesthe Au nanoparticles form films at the surface of Au colloids. We then investigatedthe spectral sensitivity and reproducibility of the Au nanoparticle films and found thatthe Au nanoparticle films were most dense and ordered at certain concentrations anddemonstrated a low detect limit.