In Situ Preparation Of Gold And Silver Nanoparticles In Biomacromolecule Nanoreactors And The Effect Of Nanoparticles On The Structure Of Protein

Based on the theme of “the interaction between biomacromolecules and nanoparticles”,we chose DNA and lysozyme as templates for preparing the gold and silver nanoparticles. Onthe other hand, we also studied the effect of nanoparticles on the structure of protein. Themain contents of this dissertation are as follows:1. Using DNA network as a template for in situ synthesis of gold nanoparticles. AuCl4-ions was first bound to the prepared DNA template based on the coordination interactionbetween AuCl4-and DNA bases, then AuCl4-was reduced to in situ form the well-dispersedgold particles on the DNA network template. And the successful synthesis of goldnanoparticles in the aqueous solution of DNA indirectly proved that the particles formed onthe DNA network were gold nanoparticles. Atomic force microscopy characterizationindicated that the size of gold nanoparticles was slightly influenced by the concentration ofDNA network and the reduction time. The gold nanoparticles on the DNA network are2-3nmin size.2. Using the biomacromolecule multilayer as the template for in situ fabricating silvernanoparticles. The (lysozyme/DNA-Ag+) multilayer films were formed by a layer-by-layertechnology, in which the lysozyme and DNA-Ag+complex were absorbed on a mica substratealternately. Then the silver ions were reduced to in situ form the silver nanoparticles in themultilayer films. The obtained silver nanoparticles on the surface of the multilayer filmsshowed relatively good stability. In addition, the size of the silver nanoparticles could bereadily turned by manipulating the number of the multilayer films or changing theconcentration of silver ions during multilayer films deposition. We have also found in theexperiment that the DNA-Ag+complexes were negatively charged spherical particles, ratherthan the linear structure reported in the literature. The average diameter of DNA-Ag+complexes was3.76±1.65nm characterized by AFM.3. Using atomic force microscopy (AFM) as the visualization method, we studied theeffect of different characteristics of nanoparticles on the structure of lysozyme and BSA. Itwas shown that the particle size, material, and shape have significant effects on the structureof protein. In the aspect of the nanoparticles size, the protein bound onto smaller nanoparticlesresults in smaller change of the protein structure. In the aspect of the materials ofnanoparticles, effect of the semiconductor nanoparticles on the structure of protein is greater than the gold nanoparticles.In the aspect of the shape of nanomaterial, the nanosheets ofgraphene oxide (GO) have greater influence on the deformation of protein structure thanspherical nanoparticles.