Preparation Of Gold And Copper Nanoclusters And Their Application In Detection Of Cu²⁺ And Hg²⁺

Mercury(Hg2+)and copper(Cu2+)ions are two kinds of common heavy metal ions,which can not be degraded and accumulated in organisms,showing strong toxicity and causing great harm to human health and environmental safety.Therefore,a variety of chemical analysis methods have been developed to detect Hg2+ and Cu2+ ions in the environment.Fluorescence sensor has made up for the shortcomings of traditional detection methods such as high cost,complex operation and long reaction time,and has become a new research hotspot in the field of biological analysis.Noble metal nanoclusters are a new type of inorganic luminescent nanomaterials,which have attracted the attention of researchers due to their high fluorescence intensity,strong stability and good biocompatibility,and have been widely used in the fields of biochemical analysis and medical imaging.Therefore,it is of great significance to further develop fluorescence sensors using noble metal nanoclusters as probes.In this study,bovine serum albumin functionalized gold nanoclusters(BSA-Au NCs)and bovine serum albumin functionalized copper nanoclusters(BSA-Cu NCs)were synthesized by one-step hydrothermal synthesis method,and a ratio type fluorescence sensor was prepared by simply combining them for the detection of Hg2+ and Cu2+ ions,respectively.The main contents of this paper are as follows:(1)Water-soluble BSA-Au NCs and BSA-Cu NCs were synthesized by using bovine serum albumin(BSA)as stabilizer and reducing agent.The BSA-Au NCs were characterized and analyzed by UV-Vis absorption spectroscopy,fluorescence spectroscopy,infrared spectroscopy,laser particle size analyzer and other instruments.The prepared BSA-Au NCs emitted pink fluorescence(?em=616 nm),while the BSA-Cu NCs emitted blue fluorescence(?em=398 nm).BSA-Au NCs and BSA-Cu NCs were mixed at a volume ratio of 2:3 to prepare dual-emission hybrid probes.The effects of storage time,pH value,temperature,fluorescence intensity and other factors on the fluorescence stability were investigated.(2)The Au NCs/Cu NCs hybrid probe takes BSA-Au NCs as response signal and BSA-Cu NCs as reference signal.When the ratio probe was used to detect 14 common metal ions,only Hg2+ and Cu2+ ions could significantly quench the pink fluorescence of BSA-Au NCs.Based on the obvious quenching effect of Cu2+ on the mixed probe,a sensitive and simple Cu2+detection method was established,which can be used for the detection of Cu2+ions in real water.In the concentration range of 0.1?1 ?M and 1?5 ?M,the response of hybrid probe to Cu2+ showed a good linear relationship with the detection limit of 23.4 nM.The effect of Hg2+ ions on the fluorescence intensity of the hybrid Au NCs/Cu NCs probe was also studied.It was found that there was a good linear relationship between the concentration of Hg2+ions and the fluorescence intensity ratio of the hybrid probe(I616/I398).Therefore,the analytical method for the detection of Hg2+ ions in actual water was established.The detection range was 0.06?1 ?M and 1?4?M,and the detection limit was as low as 19.4 nM.(3)Using EDTA and NaBH4 as masking agents,the interference between Cu2+and Hg2+ can be effectively eliminated,and the highly selective detection of Cu2+ and Hg2+ can be realized.By studying the UV-Vis absorption spectra of the composite probe before and after adding Cu2+ or Hg2+ions and the dynamic quenching constant KSV of Cu2+or Hg2+ ions to the composite probe at different temperatures,it was proved that the fluorescence quenching of Cu2+and Hg2+on Au NCs/Cu NCs hybridized probe belonged to static quenching.In conclusion,BSA-Au NCs and BSA-Cu NCs(quantum yields of 5.34%and 2.36%,respectively)were successfully prepared using BSA as template in this paper.Based on Au NCs/Cu NCs hybrid probe,fluorescence sensors for heavy metal ions Cu2+and Hg2+were successfully constructed,showing excellent detection results.In addition,EDTA and NaBH4 were used as masking agents to effectively eliminate the interference between Cu2+and Hg2+ions.The fluorescence quenching mechanism of Cu2+and Hg2+ions on the composite probe was proved to follow the static quenching mechanism by studying the changes of absorption spectra and temperature contrast experiments.The composite probe was applied to the detection of Cu2+ and Hg2+ ions in real water.In this paper,BSA-Au NCs and BSA-Cu NCs were used as hybrid probes for the first time,which broadened the combination range of ratio fluorescent probes and provided a new idea for further research and development of Cu2+/Hg2+ fluorescent sensor based on test paper.