Preparation And Application Of Copper Nanoclusters Stabilized By Poly Thymine Single Strand DNA

Recently,metal nanoparticles have aroused more and more attention.Metal nanoparticles exhibit different mechanical,electrical,optical,and magnetic property from bulk metal materials due to the volume effect,quantum size effect,surface effect of nanoparticles.And they have become a hot area in the field of ananlytical chemistry field.When the size of metal nanoparticles is smaller than 2nm,which is comparable to the Fermi wavelength of electrons,the energy level of metal electron will become discrete,leading to the excellent fluorescence property of them.This kind of materials is called nanoclusters,which is consisted of several to roughly hundreds of atoms.What is more,they also exhibit quantum size effect,surface effect and quantum size effect like the metal nanoparticles do.So they not only exhibit excellent optical properties but also show good electrical properties and catalytic activities.Copper nanoclusters,as a kind of nanomaterials,possess good optical property and lower price than gold or silver and have been considered as a more potentially nanomaterials.In recent years,various methods have been developed for the synthesis of copper nanoclusters,such as protein,thiols,DNA,polymer,amino acids and other molecules.Copper nanoclusters stabilized by these molecules show excellent propeties and have been widely used in catalysis,biological imaging,biological labeling and sensing.However,the synthesis of them is complicated and time consuming.Recently,a method for the preparation of copper nanoclusters is developed using poly thymine single strand DNA as template,which could synthesized copper nanoclusters in five minutes.Compared to other methods,this method is easier and faster.Based on this,we further investigated the application of poly thymine stabilized copper nanoclusters.Details are as follows:First,a rapid and sensitive sulfide anion detection method has been developed using the poly thymine stabilized copper nanoclusters as fluorescence probe.Using poly thymine as template,copper nanoclusters were synthesized and showed good fluorescence property.After adding S^2-,the fluorescence intensity of copper nanoclusters was reduced significantly.The amount of fluorescence quenching is dependent on the concentration of S^2-Good linearity was obtained in the concentration range of 0.125 uM to 8 uM of S^2-and the detection limit is 22 nM.This method shows good selectivity towards S^2-and good recoveries were gained in the analysis of real samples.What is more,the detection time is significantly decreased due to the rapid preparation of poly thymine stabilized copper nanoclusters.Second,a novel melamine sensing method was developed based on the fluorescence enhancement of poly-thymine stabilized copper nanoclusters for the first time.Copper nanoclusters could be synthesized in five minutes using poly thymine as template,while the quantum yield of poly thymine stabilized copper nanoclusters was very low and their application was limited.The quantum yield of copper nanoclusters is highly dependent on the structure of template molecules.When the structure of template molecule becomes more rigid,the quenching effect caused by environmental stimuli will be minimized.With the strong interaction between melamine and thymine bases,single strand poly thymine could form double strand poly thymine melamine complex.The fluorescence intensity of double strand poly thymine stabilized copper nanoclusters was higher than that of the single strand poly thymine stabilized copper nanoclusters.It is the first time to report the fluorescence enhancement of poly thymine stabilized copper nanoclusters.Based on this principle,a rapid,convenient method for melamine sensing has been developed.