Preparation And Application Of Carbon Dots And Copper Nanoclusters

Carbon dots as a member of the nanomaterials family has aroused great concern in recent years.Compared to traditional semiconductor quantum dots and small molecules of dyes,carbon dots have not only excellent optical properties,but also have low cytotoxicity and good biocompatibility and inexpensive advantages.These advantages have made carbon dots in biomarkers,biosensors,fluorescent probe biological detection,and photocatalysis,and other fields have been widely used.In addition,copper nanoclusters,as a member of the family of metal nanoclusters,have not only the advantages of high emission wavelength,high quantum yield,but also low cost,simple preparation method and good biocompatibility,and are considered to be a very practical application of the potential of nano–materials.In this paper,carbon quantum dots and copper nanoclusters were studied,and their preparation and application were studied.Specific content includes the following three aspects:1.(GQDs)with strong fluorescence properties was obtained by thermal reflux of graphene,and a method based on Au(?)–S on GQDs surface and S2– detection method were constructed.GQDs have strong fluorescence.In the presence of trace Au(?)ions,when Au(?)/GQDs system is added with trace S2–,S2– reacts with Au(?)to form gold nanoparticles.And fluorescence resonance energy transfer(FRET)occurred between the gold nanoparticles and GQDs,resulting in a sharp decrease in the fluorescence of the Au(?)/GQDs system.Under the optimum experimental conditions,the detection limit of sulfur ion is 0.2 nM,and the quenching efficiency is in good linear relationship with S2– concentration(1.5~150 nM),and a method for determining S2– is established.2.A rapid method for the detection of Fe2+ was established by using the fluorescence quenching–recovery mechanism of carbon quantum dots(CDs)by hydrothermal method using citric acid as carbon source.First,CDs were prepared by hydrothermal method.Then,manganese dioxide(MnO2)nanometer flakes were added to CDs to quench the fluorescence of CDs,and the CDs–MnO2 probes were formed by internal filtration.When Fe2+ is added to the above probe,MnO2 reacts with Fe2+ to restore the fluorescence of CDs.Under the best experimental conditions,the detection limit of Fe2+ is 0.17 ?M and the linear range is 0~2 ?M.Based on this,it provides a very effective method for the rapid and efficient detection of Fe2+.3.The copper nanoclusters(CuNCs)with fluorescent properties were synthesized by using polyethyleneimine(PEI)as template and hydrazine hydrate as reducing agent.It was found that Au(?)strongly quenched the fluorescence of CuNCs.Under the best experimental conditions,the detection limit of Au(?)was 0.06 ?M and the linear range was 0.5~15 ?M.We investigated the fluorescence quenching mechanism by X–ray.The results show that the fluorescence quenching of CuNCs is due to the photoinduced electron transfer of CuNCs and Au(?).Accordingly,a new simple and rapid method for detecting Au(?)is established.