Application Research Of Fluorescent Probe Based On Molybdenum Disulfide Quantum Dot

Fluorescence analysis has the advantages of simple operation,rapid response and high sensitivity,and has been widely used in biological analysis and environmental analysis.In recent decades,semiconductor quantum dots,organic small molecules,carbon points and metal nanomaterials have attracted wide attention as fluorescent probes.As a transition metal sulfide,molybdenum disulfide quantum dots have special electronic structure,excellent optical characteristics,good water solubility and environmental friendliness.In this paper,we mainly study the construction and analysis application of fluorescent probe based on low toxicity and easy synthesis of molybdenum disulfide quantum dots,including the design and synthesis of three kinds of fluorescent probe based on molybdenum disulfide quantum dots,and explore their performance and application to the analysis and detection of target in environmental samples.The main content is divided into the following three parts:Part I:In this paper,sodium molybdate and glutathione?GSH?were used as precursors to prepare fluorescent MoS₂ QDs by hydrothermal method.The synthesized QDs exhibited the optical properties of blue fluorescence,with an excitation wavelength of 330 nm and an emission wavelength of 430 nm.The quantum yield was 13.4%.It also had stable storage properties,non-toxicity,and excellent water solubility.Combining the excellent catalytic and optical properties of MoS₂ QDs,the first MoS₂QDs synergistic catalytic Fenton system for the sensitive detection of hydrogen peroxide?H₂O₂?and glucose?Glucose?photoluminescence sensing was developed.The sensor is characterized by the use of MoS₂ QDs as both a fluorescent indicator and a Fenton co-catalyst.As a co-catalyst of Fenton,MoS₂ QDs can effectively activate H₂O₂ to produce·OH at the nanoscale.On the other hand,MoS₂ has a kind of inherent fluorescence characteristics,which can be effectively quenched by the generated·OH.In addition,because glucose oxidase?GOD?can specifically catalyze glucose?Glucose?to generate dissolved oxygen and H₂O₂.Therefore,this study used the MoS₂QDs-Fenton sensing system and GOD to achieve the determination of Glucose,and had been successfully applied to actual samples.Under optimal conditions,the linear ranges for detecting H₂O₂ were 0.01-1.0mM and 0.1-20.0mM,and the detection limits was as low as 5 nM?S/N=3?;the linear ranges for detecting Glucose are 0.01-1.0mM and1.0-30mM,the detection limit is as low as 7 nM?S/N=3?.The method was applied to the detection of H₂O₂ and Glucose in actual samples,and satisfactory results were obtained.In addition,this work also provides an idea for the application of MoS₂ QDs in Fenton reaction to detect environmental pollutants.Part II:MoS₂ QDs with excellent fluorescence performance and good stability are prepared by using environmentally friendly milk as a sulfur source and stabilizer through a fast and easy-to-operate microwave radiation method.The excitation wavelength is 350 nm and the emission wavelength is At 445 nm,the quantum yield is8.6%.Interestingly,the addition of tetracycline hydrochloride?TC?to MoS₂ QDs solution can induce its fluorescence quenching.The experimental study found that the ultraviolet absorption of TC coincides with the excitation spectrum of MoS₂ QDs.According to the calculation of Stern Volmer's equation,there is no dynamic quenching.It is likely that the static quenching mainly participates in the fluorescence quenching of MoS₂ QDs by TC.The detection mechanism is most likely the internal filtration effect?IFE?.Based on the above background and conditions,we have designed a simple,highly sensitive,and highly selective TC measurement method.Experiments have shown that the linear ranges of detection TC are 0.01-1.0mM and 1.0-200mM,respectively,the low detection limit is 10 nM?S/N=3?without interference from other substances in the environment.The green fluorescent probe constructed in this paper was successfully applied to the determination of TC concentration in environmental samples.Part III:This article reports a simple,fast,and sensitive fluorescent probe for detecting copper ions(Cu²⁺)with high sensitivity through bovine serum albumin?BSA?protected molybdenum disulfide quantum dots?MoS₂ QDs?.MoS₂ QDs synthesized by microwave irradiation using BSA as a sulfur source and stabilizer.The synthesized QDs have good stability?such as storage stability and stability under high ionic strength?and excellent optical characteristics.The excitation wavelength is 340 nm,emission wavelength is 410 nm,and quantum yield is 9.8%.It was found that when Cu²⁺was added to the MoS₂ QDs solution,its fluorescence was significantly quenched.After fluorescence lifetime analysis,the fluorescence lifetime of MoS₂ QDs after adding Cu²⁺changed from 2.24 ns to 1.71 ns,and dynamic quenching may exist.Under the optimal experimental conditions,the line range of Cu²⁺detection is 1 nM to 50mM,and the detection limit is as low as 1 nM?S/N=3?.This article successfully used fluorescent probes for the analysis and detection of Cu²⁺in environmental samples.The probe has the advantages of easy synthesis,fast response,high sensitivity,high selectivity and has great application potential in the water environment.