Synthesis Of Water-soluble AgInZnS-GO Quantum Dots And Their Application

AgInS₂ quantum dots is a new type of ?-?-?2 semiconductor nanomaterial.It has the characteristics of adjustable fluorescence and absorption spectra,narrow emission spectra and long fluorescence lifetime,it doesn't contain the toxic heavy metals such as cadmium or lead,which shows a potential application in the fields of bioimaging,solar cells and photocatalysis.However,?-?-?2 quantum dots are generally synthesized in non-polar organic solvents,and the obtained oil-soluble quantum dots has poor dispersibility in aqueous solution,limiting the application of quantum dots in biological imaging and life sciences fields.In order to solve the hydrophobicity of ?-?-?2 quantum dots,the oil-soluble ?-?-?2 quantum dots are transferred into aqueous solution by using water-soluble graphene oxide?GO?to modify the surface of?-?-?2 quantum dots,which is beneficial to the application of ?-?-?2 quantum dots in cell labeling and in vivo imaging.In this thesis,the performance analysis of AgInZnS?AIZS?quantum dots and water-soluble AIZS-GO quantum dots and the application of water-soluble AIZS-GO quantum dots are studied.The results show that the optical properties of AIZS and AIZS-GO quantum dots are almost unchanged,and we also have studied the application of water-soluble AIZS-GO quantum dots for biological application and photocatalytic water-splitting to hydrogen.The main research results of this dissertation are as follows:?1?Preparation and performance analysis of AIZS quantum dots.The AIZS QDs was synthesized through heat injection method.The size of the QDs was studied by controlling the different reaction temperature.As a result,the fluorescence and absorption spectra showed that the size of AIZS QDs was decreased with the increasing of reaction temperature,the PL and absorption spectra showed blue shift in the visible range.The shape and structure of AIZS QDs are analyzed by TEM and XRD.It can be seen that the size distribution of QDs is very uniform and the lattice structure is obvious.Thus,the experimental results show that the cadmium-free quaternary AIZS QDs were successfully prepared,which favored its biological imaging and photocatalytic applications.?2?Preparation and performance analysis of water-soluble AIZS-GO quantum dots.The water-soluble AIZS-GO QDs was synthesized by assembling the oil-soluble AIZS QDs on the water-soluble graphene oxide via a mini-emulsion method.By comparing the optical properties of AIZS and AIZS-GO QDs,we found that the emission peak had a negligible shift and its crystal structure did not change,which laid a good foundation for the application of biological imaging and photocatalytic water-splitting to hydrogen.?3?The biological applications of water-soluble AIZS-GO quantum dots,including cell imaging and in vivo imaging.SK-BR-3 cells were labeled by AIZS-GO QDs and their fluorescence intensity was almost not decayed under fluorescence microscopy.The cytotoxicity of SK-BR-3 cells labeled by AIZS-GO QDs was investigated by MTT assay,and the cell viability of cells was analyzed by Flow cytometry analysis.It was found that the cell viability of each group was high and did not change with the increasing concentration of the AIZS-GO QDs,which indicated that the damage to cells is very little.In addition,we injected the AIZS-GO QDs into the tumor-bearing nude mice by tail vein,and it was observed that a strong fluorescence was widely distributed in the tumor-bearing nude mice for a long time,and the organs were also observed the fluorescence imaging.Therefore,these results show that the water-soluble AIZS-GO QDs have the advantage of good optical stability,biocompatibility and low toxicity.?4?Photocatalytic hydrogen production of water-soluble AIZS-GO quantum dots.The concentration of AIZS-GO QDs was measured by ICP analysis,and H2 production from irradiation of AIZS-GO aqueous solution was measured by gas chromatography analysis.The results show that the AIZS-GO QDs have the advantage of absorbing light in the visible range,as well as its unique semiconductor properties and nontoxicity,which is beneficial to the application of photocatalytic hydrogen production for QDs.In summary,the as-prepared water-soluble AIZS-GO QDs have the advantage of good optical stability,biocompatibility and low toxicity.Besides,it has a large absorption in the visible range,which is beneficial for the application of biological imaging,in vivo imaging and photocatalytic hydrogen production.