Preparation And Application Of Water-Soluble Fluorescent Probes

With the rapid development of modern industrial production,environmental problems are becoming increasingly serious,so the detection and early warning research of environmental pollution becomes particularly important.In environmental pollution,the pollution of heavy metal ions in water bodies has an impact on human health and organisms.Therefore,it is very important to develop detection technology for heavy metal ions in water bodies.Compared with other detection technologies,fluorescent sensing technology has many advantages such as low detection limit,high sensitivity,easy operation,and no need for large equipment,so it has been favored by scientific researchers.General fluorescent probes usually have the disadvantage of poor water solubility,and cannot be directly applied to the detection of ions in the water environment.For the detection technology of heavy metal ions in water samples,it is particularly important to be able to directly detect aqueous solution samples.In this paper,two types of water-soluble fluorescent probes were designed and prepared,and their ability to detect heavy metal ions was studied.The findings are as follows:Based on the photoelectron transfer?PET?mechanism,a molecular fluorescent probe PP was designed and synthesized,with phenothiazine as the light-emitting group,polyamide structure as the recognition group,and multiple diethanolamine structures were introduced on the polyamide.To enhance its water solubility.The results show that PP molecules can directly recognize Pb²⁺in water with high sensitivity,the detection limit is 9.11*10^-8M,the response speed is fast and equilibrium can be reached quickly.Using hydrothermal method,a kind of nitrogen-doped carbon dots N-CDs were prepared with barley as carbon source,and a series of structure and performance characterizations were performed.The results show that N-CDs have a more regular morphology,a uniform particle size,a distribution in the range of 4.5-7 nm,an average particle size of 5.8 nm,a variety of nitrogen-containing oxygen-containing functional groups,and good fluorescence performance.N-CDs can realize the recognition response to Hg²⁺with good specificity,and the detection limit is 0.48 ?M.Because the prepared carbon dots have lower cytotoxicity and higher cell compatibility,they can also be used for imaging of living cells and detection of Hg²⁺in the intracellular environment.Using broad beans and broad bean pods as carbon sources,carbon dots CCDs1 and CCDs2 and nitrogen-doped carbon dots CNCDs1 and CNCDs2 were prepared by hydrothermal method.It has been found that the use of ethylenediamine to dope nitrogen at the carbon dots during the preparation process can effectively reduce the size of the carbon dots,thereby increasing the fluorescence quantum yield of the carbon dots.The surface of the prepared nitrogen-doped carbon dots is rich in water-soluble and strong nitrogen-oxygen functional groups,and can directly recognize Hg²⁺in aqueous solution.CNCDs1 has low cytotoxicity and can be used for imaging of living cells and recognition of intracellular Hg²⁺.Using peas and pea pods as carbon sources,carbon dots WCDs1 and WCDs2 and nitrogen-doped carbon dots WNCDs1 and WNCDs2 were prepared by hydrothermal method.It has been found that the use of ethylenediamine to dope nitrogen at the carbon dots during the preparation process can effectively reduce the size of the carbon dots,thereby increasing the fluorescence quantum yield of the carbon dots.The surface of the prepared nitrogen-doped carbon dots contains a large number of water-soluble nitrogen-oxygen functional groups,which can directly recognize Hg²⁺ in aqueous solution.WNCDs1 has low cytotoxicity and can be used for imaging of living cells and recognition of intracellular Hg²⁺.