The Studies On The Interaction Of Gold Nanoparticles Colloid With Ptoteins

Protein is one kind of extremely important biomacromolecule and is the basic of living things. Usually,when we desire to have further understanding about the interaction of nanomaterials andbiomacromolecules and the resulting nanobiological implications of these interactions, protein is chosen asthe research subject To clarify the interaction of proteins and nanomaterials is helpful to determine theproperties of nanomatetials, which will probably cause undesired impacts and promote the safe designs ofnanomaterials. Furthermore, the understanding of the interaction is the basic of the research for theinteraction of nanomaterials and the cells, tissues, organs in organisms even the organisms.People focus on gold nanoparticles for their excellent stability, special properties, such as, surfaceeffects, small-scale effects, optical effects, biocompatibility and their promise in diverse field, includingbioanalytical chemistry, biomedicine, industrial catalysis and fast test in food safety. Therefore, it is veryimportant to research the biotoxicity of gold nanoparticles. Presently, amounts of techniques are used tostudy the interaction of biomacromolecule and gold nanomaterials qualitatively. That is becausequantitative research should need the accurate concentration of the gold nanoparticles colloid which hasbeen yet hard to obtain.In this paper, an analytical expression among macromolecule concentration, electrolyte concentrationand the solution osmotic pressure is obtained on the basis of van’t Hoff equation and Donnan equilibrium.The expression was further applied to a colloid solution of3nm glutathione-stabilized gold nanoparticles.The concentration of the colloid solution and the average net ion charge number for each gold nanoparticlewere determined with the measured osmotic pressure data. The values were4.14×10-5mol L-1and5.50respectively. Meanwhile, combining the gold contents of the solutions obtained by means of atomicabsorption spectrophotometer, we determined the value for the average number of gold atoms per3nmgold nanoparticle synthesized in our work was479.The interactions of3nm glutathione-stabilized gold nanoparticles colloid with trypsin, ovalbuminhave been investigated by UV spectra, fluorescence spectra under physiological conditions. The bindingconstants of gold nanoparticles-proteins fitted from the spectral data in our work are between107~108L mol-1. We combine the values of Hill constants (m>1) which show the high degree of cooperativity ofparticle-proteins binding with the Synchronous Fluorescence and UV spectra researches to speculate thatthe interaction between proteins studied and gold nanoparticles at physiological pH results in the formationof extended gold nanoparticles-proteins aggregates, which has altered the structures of proteins largely.These studies provided basis for further studies on the biotoxicity of gold nanoparticles.