Properties And Applications Of Gold Nanoclusters Under Molecular Crowding Environment

Gold nanoclusters(GNCs)are composed of ligands and several to hundreds of Au atoms and Au(?)ions.They exhibit many fascinating features,including unique fluorescence,facile synthesis,good biosafty,and environmental friendliness.Therefore,GNCs are recoganized recently as one of the most attractive research hotspots in nanoscience.The effective regulation of the fluorescence properties of GNCs plays a vital role for their development and application in the fields of environmental monitoring,biochemical analysis and bioimaging.In this paper,molecular crowding is used as a noval environmental parameter to regulate the fluorescence of GNCs by mimicking the crowding environment in biological cell.The effect of molecular crowding on the fluorescence properties of GNCs protected by peptide and protein is investigated.The interactions between gold nanoclusters and protamine/carbon dot(CDs)in molecular crowding environment are further explored.On this basis,fluorescence methods for detection of protamine,heparin and copper(II)ions were developed.The main contents of this paper are as followed:In the second chapter,the effect of molecular crowding on the fluorescence properties of glutathione-protected GNC(GSH-GNCs)and bovine serum albumin protected GNC(BSA-GNCs)was studied.It was found that molecular crowding can significantly enhance the fluorescence emission intensity and quantum yield of GSH-GNCs through aggregation induced enhanced emission(AIEE)effect.Molecular is also capable of promoting the interaction between GSH-GNCs and protamine,thus improving the fluorescence response sensitivity to protamine and heparin.On this basis,a simple and effective fluorescent method for the detection of protamine and heparin was proposed.The detection range of this method was 0.7–3.0 and 0.05–2.8?g·m L^-1,and the detection limits of protamine and heparin were 7.5 and 1.7 ng·m L^-1,respectively.Meanwhile,it is found that the secondary structure of BSA ligands was changed under the crowded environment,leading to the decrease in fluorescence emission of BSA-GNCs.In the third chapter,the interaction between GSH-GNCs and CDs under molecular crowding environment was explored.It is found that the molecular crowding effect can significantly enhanced the electrostatic interaction between GSH-GNCs and CDs,which promotes the fluorescence resonance energy transfer(FRET)from CDs to GSH-GNCs.The efficiency of FRET system was increased from 39%in dilute solution to 60%of the molecular crowded solution.Based on this,a copper(?)ion detection method was developed by using CDs-GNCs as fluorescence ratiometric probe.The detection range of this method is 0–20.0?M,and the detection limit is 47 n M.This method can be applied to the detection of copper(II)ions in real water samples.