Study On The Synthesis Of Biocompatible Nanoparticles By Cysteine

The biocompatibility of nanomaterials is one of the challenging issues faced by synthetic chemists. Recently, a large number of biomaterials have been extensively applied to produce and assemble nanomaterials, for example, peptide, DNA, protein, microorganism. Amino acids is the most basic substance that form organisms and proteins, which is also related to life activities. In this paper, cysteine has been studied and carried out as the following two sections of work:(1) Multiple shapes and sizes of nano- and micro-structured cystine aggregates, including spheres, rods, spindles, dendrites, and multipods, were easily synthesized just by adjusting the concentrations and pH values of L-Cysteine solutions under ultrasonic irritation. Importantly, highly monodispersed nanospheres of cystine aggregates with the size of 225 nm in diameter without any other shapes were easily obtained. The produce have been characterized by XRD and FTIR. Circular dichroism spectra have been used to measure intermolecular bond in different pH aqueous solution. In addition, we studied the stability of nanospheres of cystine aggregates in different condition.(2) A simple method for one-step synthesis of cystine-capped gold nanoparticles in aqueous solution at room temperature has been developed. Cysteine was used as reducing agent in react processing. The thiol group of cysteine undergoes dimerization to form cystine via the oxidation of two thiol groups. The amino group of cystine is combined with the surface of gold nanoparticles to protecting and controlling the size of gold nanoparticles. The shape and size of gold nanoparticles is controllable just by adjusting the reactant molar ratio, pH value, ion concentration and temperature. In addition, we studied the stability of gold nanoparticles in different condition. The analysis of samples by XPS provided the information regarding the chemical composition of product and the chemical bond between the amino group of cystine and the surface of gold nanoparticles. The analysis of FTIR for samples characterized the variation of intermolecular hydrogen bonds of cystine molecules in different pH.