Analysis And Application Of Synthese Of Fluorescent Au Clusters Using Self-Assembled Tripeptides As Soft Templates

Due to extremely small size,unique physicochemical properties and strong photoluminescence,AuNCs are widely used in bioimaging and biosensing.AuNCs of ligand method synthesis is difficult to control the size and the fluorescence efficiency.So it is great significance to synthesize AuNCs with mild process,high fluorescence yield and controllable size.In view of the current situation above,AuNCs with different sizes and fluorescence were synthesized using self-assembled tripeptides as soft templates in this work.What’s more,AuNCs with red fluorescence on FCC templates were applied to fluorescence imaging of Hela cells.The main research work is as follows:Three kinds of tripeptides Cys-Phe-Phe(CFF),Phe-Cys-Cys(FCC),Pro-Cys-Phe(PCF)were self-assembled into three soft templates with different morphologies(nanofibers,nanorings,and nanoparticles)by controlling the temperature cycling conditions.Then the molecular dynamics simulation(MD)was used to research the process of tripeptide self-assembly.The simulation results showed that the soft template morphology after stabilization was consistent with the experimental results.Finally,the stability of the soft template was further studied by the circular dichroism(CD)spectra.The results show that the topography and intermal structure of the soft template do not change significantly after the synthesis of AuNCs.AuNCs were synthesized using three soft templates and were characterized by the transmission electron microscopy(TEM),matrix assisted laser ionization time of flight mass spectrometry(MALDI TOF MS),uv-visible spectroscopy and fluorescence spectroscopy.The results show that AuNCs on the surface of the soft template have different Au core.And AuNCs will further aggregate to form larger AuNCs or gold nanoparticles(AuNPs)with different size.AuNCs with different Au cores have different fluorescence properties,which can be explained by the change of surface potential.Theoretical research of AuNCs including processes of synthesis and aggregation and properties of the different sizes and fluorescence were carried out.Then a physical model was proposed to describe the sizes of AuNCs after the aggregation on different tripeptide soft templates.It is found that the distribution of-SH(number,distance)and the aggregation degree(AP)of the soft templates are the decisive factors of AuNCs size.It was found that AuNCs with red fluorescence on FCC templates had large stokes shift and good biocompatibility.So it had been successfully applied to fluorescence imaging of Hela cells.