Preliminary Study On The Application Of AglnS₂ In Visible Light Photocatalysis And Biological Detection

Objective:Agln S₂（AIS）nanoparticles were synthesized,and the visible light photocatalysis of AIS on organic pollutants and inorganic metal ions in water was explored.The fluorescence quenching effect of Cr（III）on AIS QDs was used to establish a method for the detection of Cr（III）.Based on the unique optical properties of AIS,the preliminary application of AIS QDs in biological field is discussed.Methods:1.Agln S₂nanoparticles were synthesized by low temperature liquid phase method.The samples were characterized by X-ray diffraction（XRD）,scanning electron microscopy（SEM）,high resolution transmission electron microscopy（HRTEM）,N₂adsorption-desorption isotherm and pore size analyzer（BET）,X-ray photoelectron spectroscopy（XPS）and ultraviolet-visible diffuse reflectance spectroscopy（UV-vis DRS）.The visible light photocatalytic properties of Agln S₂nanoparticles were studied by using potassium dichromate（Cr（VI））and p-nitrophenol（p-NP）as model pollutants.2.In the process of visible light photocatalytic oxidation of p-NP by AIS and the visible light photocatalytic reduction of Cr（Ⅵ）,n-butanol（n-BA）,sodium oxalate（SO）,potassium dichromate（Cr（VI））/potassium persulfate（K₂S₂O₈）and 1,4-benzoquinone（BQ）were used as hydroxyl radical（OH·）,hole（h⁺）,electron（e^-）and superoxide radical（·O₂^-）trapping agents,respectively.The active species were determined by investigating the reduction efficiency of Cr（VI）and the oxidation efficiency of p-NP.The mechanism of visible light photocatalysis of AIS nanoparticles for the reduction of Cr（VI）and the oxidation of p-NPwas discussed.3.AIS QDs solution was synthesized directly by aqueous phase synthesis method.The samples were characterized by high resolution transmission electron microscopy（HRTEM）,X-ray photoelectron spectroscopy（XPS）,ultraviolet-visible spectroscopy spectrum（UV-vis）and fluorescence spectrum（PL）.Based on the fluorescence quenching effect of Cr（III）on AIS QDs,a fluorescence quenching method for Cr（III）detection was developed.4.The toxicity of AIS QDs to cells was determined by MTT method,and AIS QDs was used as a probe,the recognition effect of AIS QDs probe on the cancer cells was judged by the biological imaging function of laser confocal microscope.Results:1.The visible light photocatalytic degradation results showed that the reduction efficiency of 20 mg AIS to 50 ml Cr（VI）(10 mg×l^-1)could reach 100%within 15 min,and the oxidation efficiency of 20 mg AIS to 50 ml p-NP(10 mg×l^-1)is more than 50%within150 min.After six cycles,AIS maintains good structural stability and ensures the good cycling performance of solid catalyst.The narrow band gap（1.49 e V）of AIS makes it have a good absorption of visible light.At the same time,the prepared AIS sample has a large specific surface area,which provides a large number of reactive centers for AIS.Therefore,AIS showed excellent visible light catalytic reduction activity and visible light catalytic oxidation activity at the same time.2.The capture experiments of active species showed that in the visible light photocatalytic reduction of Cr（VI）,photogenerated electrodes（e^-）were mainly involved in the process of reduction,and in the visible light photocatalytic oxidation of p-NP,·O₂^-and·OHwere mainly involved in the oxidation process.3.The particle size distribution of AIS QDs synthesized by aqueous phase method is uniform,about 3-8 nm.The method established based on the fluorescence quenching of AIS QDs has the advantages of high sensitivity and low detection limit.4.AIS QDs is not toxic at low concentration within 24 h.As a fluorescent probe,AIS QDs can be used to accurately identify the normal cells and the tumor cells.Conclusion:The AIS nanoparticles synthesized by low temperature liquid phase method not only have excellent visible light photocatalytic reduction activities,but also have excellent visible light catalytic oxidation activities,which has a good application prospect in solving environmental pollutants.The AIS QDs prepared by aqueous phase synthesis can be used for the detection of Cr（III）based on the fluorescence quenching effect,the method not only has high sensitivity,but also has low detection limit.Low concentration AIS QDs,is not toxic within 24 h,as a fluorescent probe,can be used to accurately identify normal cells and tumor cells.