Study On Ligand Exchange Method In Monodispersed Au/Ag Nanoclusters With Water Solubility

Small-sized metal clusters have the advantages of magnetism,fluorescence,chirality and biocompatibility,which promote their applications in the fields of antimicrobial,bioimaging,drug delivery and sensing.Among them,using nanomaterials as drug carriers(modifying anticancer drugs on the surface of nanoparticles)or preparing metal clusters coated by targeted groups(such as folic acid)of cancer cells and small molecules of anticancer drugs by chemical modification are common means to exert anticancer functions.Among them,drug carriers mainly use the passive targeting effect of metal nanoclusters to make metal nanoclusters carry anti-cancer drugs into and kill cancer cells,while functional clusters mainly target cancer cells through active targeting groups to achieve anti-cancer function.Compared with faded drugs,this method can increase the amount of anti-cancer drugs entering cells and increase the utilization rate of drugs.In addition,the way of heating locally enriched tumor cells by photothermal effect is also an important way to achieve anti-cancer function.In order to use water-soluble nanoclusters better,we hope to obtain metal nanoclusters with high water-soluble,monodisperse,low toxicity and fluorescence properties.Firstly,the traditional methods of synthesizing water-soluble noble metal nanoclusters include one-pot method and ligand exchange method to synthesize the crude products of water-soluble metal nanoclusters.Secondly,we need to separate and purify the crude products,which is the premise of the follow-up work.Solvent extraction,gel electrophoresis and chromatography are often used to separate and purify the crude products of synthetic metal nanoclusters.With the development of metal nanoclusters,there are many characterization methods for metal nanoclusters,including ultraviolet-visible absorption and fluorescence measurements,which can study the optical properties of metal nanoclusters.In addition to mass spectrometry,transmission electron microscopy,scanning electron microscopy,nuclear magnetic resonance,X-ray photoelectron spectroscopy,Fourier transform infrared spectroscopy and other characterization methodsAlthough small metal nanoclusters show great potential in anti cancer,antimicrobial and biosensor applications,there are still many difficulties in the preparation of monodisperse clusters.Traditional methods for synthesizing water-soluble noble metal nanoclusters include one-pot method and ligand exchange method.However,due to the inaccurate control of reaction conditions such as the amount of reductant and ligand in the synthesis process,it is impossible to control the homogeneity of the properties of the synthesized products,such as the wide and uneven size distribution of the synthesized metal nanoclusters.This phenomenon leads to many difficulties in the further popularization and application of small clusters.In order to solve the above problems,a two-phase ligand exchange method for the synthesis of water-soluble clusters,which is easy to operate and generally suitable for the protection of different drug molecules,has been developed.This method first synthesizes a specific precursor of gold and silver nanoclusters protected by phenylacetylene and triphenylphosphine,then uses this precursor to exchange ligands with a series of water-soluble thiols(e.g.thiopronine,captopril,N-acetyl-L-cysteine,p-mercaptophenyl acid,glutathione and thio-malic acid)to synthesize a series of monodisperse gold and silver alloy nanoclusters.Cluster.The morphology of water-soluble metal nanoclusters was tested by transmission electron microscopy,and the characteristics of monodispersity and ultrasmall size were confirmed.In addition,the structure was characterized by ultraviolet visible absorption spectroscopy,extended x ray absorption fine structure spectroscopy and electrospray ionization time of flight mass spectrometry.It was found that the main composition of the synthesized clusters was(AuAg)44.Based on the synthesis method of universal aqueous phase clusters developed above,the ligand carboxyl bonds of Tiopronin-protected gold and silver nanoclusters were modified to be the carriers of the classical anti-cancer drug adriamycin,and the metal nanoclusters had two properties of anti-cancer and fluorescence.This series of experiments confirm the two-phase synthesis of water-soluble metal nanoclusters based on the oil-water phase and their potential applications in biology.