The Preparation Of Fluorescent Copper Nanoclusters And Application In Sensing Detection

In recent years,copper nanoclusters have attracted widespread attention due to their excellent water solubility,biocompatibility,stability,and high quantum yield.As a good and potential fluorescent nanomaterial,it has been widely used in chemiluminescence and analytical applications.In this thesis,two kinds of amino acids and a thiol compound were used as ligands and reducing reagents.The new fluorescent CuNCs have been prepared by microwave-assisted and ultrasonic synthesis methods.The new photochemical sensing detection methods for Ag+,Fe3+ and glutathione were established based on the fluorescence intensity change of quenching/enhancement.It includes the following five chapters.Chapter 1:The development of copper nanoclusters was reviewed.The properties,synthesis methods and sensing detection applications of copper nanoclusters were summarized.The design ideas of this thesis were put forward.Chapter 2:N-acetyl-L-cysteine(NAC)was used as ligand,and NAC protected water-soluble copper nanoclusters were synthesized via sonochemical method.The as-prepared NAC-CuNCs were characterized by UV-visible absorption spectrometry,fluorescence spectrometry,fourier infrared spectrometry,transmission electron microscope and nanoparticle size potential analysis techniques.The synthesis conditions of NAC-CuNCs were optimized including ultrasonic power,NAC/Cu(N03)2·3H20 molar ratio and pH.The formation process of NAC-CuNCs was inferred.The obtained NAC-CuNCs showed 1.20 nm particle size,emission at 620 nm with red fluorescence,QY 4.4%and fluorescence lifetime 451.05 ns.Based on the good selective respond of NAC-CuNCs to Ag+,a new sensing detection method has been successful established with a linear range of 1.64×10-10-1.16×10-8 mol·L-1 and LOD of 7.76×10-11 mol·L-1.The method has been successfully applied to the detection of Ag+in the actual water samples.Chapter 3:Sodium 2-mercapto-5-benzimidazole sulfonate(MBISA)was used as reducing and protective reagent.A water soluble and stable copper nanocluster(MBISA-CuNCs)with red fluorescence was synthesized by sonochemical method.The synthesis process was simple and environmentally friendly.The cost was low and the tedious treatment was not required.The UV-visible absorption spectrometry and fluorescence spectrometry were used to characterize the CuNCs.The excitation wavelength and emission wavelength of the optimal MBISA-CuNCs were 332 nm and 642 nm respectively.And the results showed that glutathione(GSH)could enhance the fluorescence intensity of the MBISA-CuNCs.Based on this enhanced fluorescence phenomenon,a novel determination method of GSH with good selectivity was described.The linear range of the method was 6.59×10-7 to 4.26×10-5 mol·L-1(R2=0.996),and the detection limit was 4.46×10-7 mol·L-1.The proposed method has been applied successfully in the real samples.Chapter 4:3,4-dihydroxyphenylalanine(DOPA)was used as protected and reduced reagents.The fluorescent DOPA-CuNCs were synthsized by microwave radiation method.The UV-visible absorption spectrometry fluorescence spectrometry were used to study the spectral properties of DOPA-CuNCs.The effects of the mole ratio of DOPA/Cu(NO3)2·3H2O,microwave radiation time and power on the fluorescence of DOPA-CuNCs were studied.The investigation results showed that Fe3+ ion could induce the fluorescence enhancement of the copper nanoclusters.After optimizing the experimental conditions,a new detection method for Fe3+ with good selectivity was established.The detection limit was 9.15×10-13 mol·-1,and the linear range was 1.49×10-12-1.9×10-9 mol·L-1.The proposed method is simple,fast and has a wide detection range.It has been successfully applied to determine the concentration of Fe3+ in actual samplesChapter 5:The as-synthesized new copper nanoclusters(CuNCs)and the application in fluorescent sensing system were summarized.The CuNCs were appied in detection of small molecules and metal ions.And the future work was prospected.