Preparation,Characterization And Application Of Novel Functional Fluorescent Gold Nanoclusters

As a new kind of fluorescent nanomaterials with rapid development in recent years,Fluorescent Gold Nanoclusters?AuNCs?have attracted more and more attention due to their excellent physical and chemical properties.In many of the synthesis methods,the template method is the most environmentally and friendly approach,and because of the ligands are generally biological molecules,making its subsequent biological applications more convenient and efficient.However,they also have some problems,such as low fluorescence quantum yield,insufficient function,bad specificity and so on.We still need methods of synthesis and functional explorations of AuNCs,to get more excellent fluorescent gold nanoclusters,and expand its function in the detection,biological imaging and medical applications with deeper breadth and width.In this paper,we studied the synthesis and properties of Fluorescent Gold Nanoclusters.The main contents are as follows:1)By using a mild one-step synthesis method,and using the pentapeptide CRGDS as a stabilizer and a tumor recognition ligand,we synthesized a novel active targeting AuNCs?C5-AuNCs?.Because the special peptide sequence RGD can be recognized by?_v?₃ integrins,which over-express in tumor cells surface.So it has a high degree of tumor specificity,and in vivo experiments,after intravenous injection,the drugs can be obtained through fluorescent signals,moreover,tumor and liver uptake ratio can reach 9.3.The ultrasmall hydration diameter and zwitterionic surface properties of C5-AuNCs promote their urinary excretion efficiency,so that the urinary excretion of 24h can reach 82%after injection.2)Nucleolus is a very important subcellular structure.By using three peptide KCK with positive charge as surface stabilizer,we synthesized deep red fluorescent AuNCs?K3-AuNCs?with 680nm fluorescence emission.This kind of AuNCs has the advantages of deep red fluorescence emission,long Stokes shift,broad excitation range,low toxicity,good light stability and so on.Depending on the ultrasmall size and surface positive charge of K3-AuNCs,they can efficiently accumulate in the nucleolus,so as to realize the labeling of the nucleolus.Based on this specificity,fluorescence imaging techniques can be used to study the nucleolar morphology.In addition,we also explored the structure and mechanism of nucleolus staining of the materials.3)The development of nanotechnology based on nucleic acid depends on the efficient assembly of DNA or RNA with nanomaterials.In recent years,there are many corresponding nanomaterials,which has promoted the progress of nucleic acid nanotechnology.Based on the excellent properties of fluorescent gold nanoclusters, a new kind of fluorescent AuNCs?K4-AuNCs?were synthesized by using GSH and KRKC as the stabilizers.The material has the advantages of simple synthesis method and good resistance to photobleaching.The interaction between K4-AuNCs and RNA or DNA was found to be a phenomenon of assembly,and the fluorescence was enhanced after the nucleic acid assembly.Our assembly of nucleic acid can be characterized in fluorescence response,enzyme response,two structural changes,aggregation state and cellular uptake efficiency,in addition,we also explore its potential application as a gene transfection reagent.