Study On Properties Of Core-shell Nanorods And Localized Surface Plasmon Resonance Based On Core-shell Nanorods Self-assembly

Nanoscience is one of the important fundamental researches in modern science andtechnology. Due to surface effect, small size effect and quantum tunnel effect of nonmaterial,nanoparticles have many physical and chemical properties which are different fromcorresponding bulk materials. Nanorods, as a type of nanomaterial, the anisotropy indimensions leads their localized surface plasmon resonance have two absorption peak: thefirst one is due to the plasmon excitation along the long axis, is called the longitudinallocalized surface plasmon resonance（LSPR）. The second is due to an excitation along theshort axis, is called the transverse localized surface plasmon resonance（TSPR）. Nanorods areof unique optical properties, and have been applicated in medical, sensing and detection. Thisthesis mostly centre on the study of localized surface plasmon resonance of gold nanorods andthe self-assembly of core-shell gold nanorods which rooted from gold nanorods.（1） gold nanorods were prepared by silver ion-assisted seed-mediated growth method.Core-shell gold nanorods were fabricated by gold nanorods reacting with sodium thiosulfate.Under acidic contidions, core-shell gold nanorods would be self-assembly in the presence ofcysteine. The investigation exhibits that the concentration of cysteine will affect the degree ofself-assembly of core-shell gold nanorods. On the other hand, no clear self-assembly isoccurred after core-shell gold nanorods mixing with cysteine in the neutral medium. With theaddition of Cu²⁺, however, an obvious coupled plasmonic band is appeared, arisen from theformation of complexation between Cu²⁺and cysteien molecules immobilized on thecore-shell gold nanorods.（2） EDTA is an important comlexing agent. in low concentration of EDTA, the core-shellgold nanorods form self-assembly structure by means of end-to-end. However, in higherconcentration of EDTA, another side-by-side self-assembly fashion is observed.（3） A novel detection of copper ion has been developed based on the change of localizedsurface plasmon resonance property of gold nanorods. With the mixture of gold nanorods,Na₂S₂O₃in the presence of Cu²⁺, an interesting observation of longitudinal plasmon wavelength blue-shift is appeared. The degree of blue-shift depends on the amount of Cu²⁺inthe solution. Accordingly, a selective and sensitive assay for detection of Cu²⁺is formed.