DNA Directed Synthesis, Self-assembly Of Metallic Nanoparticles And Plasmonic Property Study

The plasmonic properties of metallic nanoparticles have been widely applied in biodetection, phtoovalatic, photothermal therapy and catalyst. Both the parameters like particle size, shape, composition and inter-particle plasmon coupling effect particles’ s plasmonic properties. During the practical applications, there is a great demands in preparing metallic nanostructures with tunable plasmonic properties. The most accessble tools to adjust the plasmonic properties of metallic are controlling the morphology of nanoparticles and inter-particle plasmon coupling. However, many challenges still exist for fine controlling the morphology of particle and arranging nanopaticles in pre-designed patterns.DNA, as the reservoir of life information, recently have been widely studied as versatile nanomaterils。Along with the developing of DNA nanotechnology, DNA have been used in inducing self-assembling and mediating the growth of metallic nanoparticles. Depending on its highly programmable DNA sequence and adjustable length. DNA was mostly suitable to achieve fine control over particle’s morphology.The main topic of our work is based on two characters of DNA, 1, non-specific adsorption beheavior on inorganic surface, 2, the specific recognition ability between to complementary single strand DNA. The character 1 faciliate the synthesis of complex metallic nanostructure and character 2 provide a way to achieve controllable assembly.This work can be divided into two parts, 1, DNA mediated the synthesis of complex nanostructures, including chapters 2, 3 and 4. 2, DNA-based nanoparticle self-assembly, including chapters 5 and 6.In chapter 2, we studied the relationship between the DNA adsorption behavior and the formation of hollow gap. Four bases exhibited distinct adsorption behavior on gold nanoparticle, so were the single strand DNA with different sequences. The appear of hollow gap relied on the formation of DNA self-assembled monolayer. Taking advantage of this phenomenon, we developed a simple way to study the DNA adsorption behavior on different substrates.In chapter 3, we elucidated the growth mechanism of plasmonic hollow gaped core-shell nanostructure by small angle X ray scattering(SAXS). Compared with traditional methods, like TEM, SAXS give a direct characterization of 3-D geomentrical parameters of gold nanostructures. Furthermore, no pre-treatment was required for the sample characterization. At last, we also studied the plasmonic properties of each intermediate products.In chapter 4, we sudied the plasmonic property of nanogaped stellate nanostructure. Through finely adjusting the its surface roughness, we investigated the localized surface plasmon resonant(LSPR) and surface enhanced Raman scattering(SERS) of seven stellate nanostructures. Both tunable plasmonic properties and SERS substrate with internal referencing were achieved.In the second section, in chapter 5, we reported the fabrication of single layer nanoparticle plasmonic film. The plasmonic nanostructures prepared from DNA nanotechnology have been widely reported, however, less collective plasmonic were studied among these nanostructure. Here, we found the prepared plasmonic film exhibited water induced reversible color change. The intriguing plasmonic property was attibuted to the changed inter-particle distance duiring hydration and dehydration process.In chapter 6, we achieved quantative and regio-specific DNA modification on the surface quantum dots(QDs) by combing surface charge repulsive, steric hindrance and DNA nanotechnology. The prepared functional quantum dots was used for constructing diverse QD-Au complex.From our research, we successfully prepared gold nanostructure with fine controllable surface morphology and delicate particle arrangement. Subsquently, we also studied the plasmonic property of prepared gold nanostructures. At last, I give a brief summary and prospect of my work.