The Study Of AuNPs Green Synthesized By Vine Tea Extract

Gold nanoparticles (AuNPs) have been very important nano materials due to their unique surface plasmon resonance (SPR) and multiples surface functionalities, and used in a broad range of applications in biomedical science, such as drug delivery, tissue/tumor imaging, bio-labeling, biosensors devices, photothermal therapy and electrochemical immunoassay. Currently, AuNPs have been synthesized using a variety of methods, including chemical and physical methods. Although most of the methods can successfully produce pure and well-defined AuNPs, these methods are potentially dangerous to the environment and restricted in the application of bionanotechnology. So biosynthetic methods employing either microorganisms or plant extracts have emerged as an eco-friendly, simple and green alternative to chemical and physical synthetic methods. Biomolecules secreted by the biomass can act as both reducing and capping agents during the reaction. AuNPs conjugated to biomolecules are more biocompatible and offer necessary conditions at the field of biomedical science. This paper mainly study AuNPs were prepared by vine tea extract and dihydromyricetin(DMY) and research on the influence of the preparation of anisotropic AuNPs by vine tea extract adding shape-control agent. Main contents:1) We studyed the synthesis of AuNPs produced by the reduction of chloroauric acid using vine tea leaf extract. The size and morphologies of AuNPs were characterized by UV-vis-NIR spectrophotometer and transmission electron microscopy (TEM). The studies showed that the shape and size anisotropic AuNPs can be fine-tuned by varying the dosage of the vine tea extract, the temperature and the pH value of the reaction solution. We also study the effect of AuNPs prepared by vine tea extract under the different extraction time and the stability of AuNPs prepared by vine tea extract. It can be seen that the amount of the vine tea extract played an important role in the process of AuNPs formation and controlled anisotropic AuNPs appearing and disappearing and it was helpful to form gold nanotriangles under weak acid condition.2) We investigated the biosynthesis of AuNPs using dihydromyricetin (DMY) without adding external surfactant, capping agent or template. The synthesized nanoparticles were characterized by using UV-vis spectroscopy, transmission electron microscopy (TEM), Fourier transform infrared (FTIR) and particle size analyzer. The effects of nHAuC14/nDMY ratios, process temperatures and reaction time were discussed respectively. The TEM images showed that anisotropy growth of AuNPs happened at pH=4.5-5.5. It is supposed that DMY or DMY oxidation products were directly adsorbed on the surface of AuNPs at the ratio of nHAuCl4/nDMY being1:3-1:1in the reduction process. Besides, the monodisperse and uniform AuNPs were easily obtained at higher temperatures(90℃). We preliminary discussed the reduction mechanism of the preparation of gold nanoparticles prepared by DMY.3) We studyed the effects of shape-control agent on the morphology of bio-genically prepared gold nanoparticles. It had been shown that the presence of shape-control agent can significantly influence the morphology of AuNPs during the synthesis process. The presence of Cl-promoted the growth of nanowires, whereas I-ions distorted the triangle nanoparticles to induce the formation of aggregated spherical nanoparticles. The presence of100μL-300μL Ag+made the side length of triangle AuNPs increased and the shape boundary of AuNPs was not clear when the concentration of Ag+was under500μL. The presence of100μL hexadecyl trimethyl ammonium bromide (CTAB) made the number of triangle AuNPs increased and the solution of AuNPs formed black precipitate with the amount of CTAB increased.