| PurposeTo explore a synthetic strategy aimed at fabricating hydrophilic AgInS2QDs in aqueous media, and discuss utilization for molecular imaging.MethodsAgInS2QDs were prepared in aqueous media and were modified by chemical and biological methods to make functional. Then, the cytotoxicity, in vitro and in vivo imaging experiments were carried out to comprehensively evaluate QDs’utilization for optical imaging.Contents(1) AgInS2QDs were prepared in aqueous media and the influence of mole ratio of AgNO3and In(NCO3)3and shelling by ZnS on optical properties was discussed. On this basis, AgInS2-ZnS QDs were modified to prepare AgInS2-ZnS-EDR and AgInS2-ZnS-EDR-FA QDs which were functional.(2) MTT method was used to detect the security of AgInS2-ZnS QDs with different concentrations (50nM,100nM,100nM,150nM,250nM,300nM).(3) The function of AgInS2-ZnS-EDR and AgInS2-ZnS-EDR-FA QDs was tested by using them in Hela tumor cell imaging.(4) Nude imaging experiments were carried out to verify in vivo imaging effect of AgInS2-ZnS QDs through subcutaneous injection and tail vein injection.Results(1) On condition that molar ratio of AgO3and In(NO3)3was1:16, fluorescence emission intensity of AgInS2-ZnS QDs was the highest and QY was28%. After inorganic cladding AgInS2QDs by ZnS, QY was improved and shelling2times was the best. The QDs were crystallized, uniform sized and had good dispersibility. Experimental conditions required for synthesis method was simple and QDs could be synthesized directly in air conditions. And operation was simple and had good repeatability. Reaction solvent was water and drawbacks such as large consumption of time and energy during high temperature reaction of organic solution were avoid. This provides a convenient method for direct preparation of water-soluble QDs.(2) QDs has become the focus of attention of many researchers as excellent optical properties. But the security issues of QDs is one of key problems that restrict application. In this paper, MTT was used to assay security of AgInS2-ZnS QDs and the results showed that AgInS2-ZnS QDs had good security and AgInS2-ZnS QDs with low concentrations did not affect cell viability. This approach provides a new idea for development of new low-toxicity quantum dot probes.(3) EDR, whose molecular weight is148, is a kind of PEG molecule with amino on both ends. The results showed that EDR could reduce or eliminate non-specific adsorption of QDs on cell surface. FA is one of the most commonly used tumor marker as is highly expressed in many tumor cell surface. The results showed that Hela tumor cells could specifically engulf QDs with FA. It was proved that AgInS2-ZnS-EDR-FA fluorescent probes could labeled Hela tumor cells and this provides the basis for using QDs on detection of malignant cells.(4) In vitro imaging only part of information of the biological can be understand, but more and more important issues should be solved through in vivo imaging of livings. Whether QDs can become a kind of valuable fluorescent probes lies in whether it can be used for in vivo imaging. The results showed that emission light of AgInS2-ZnS QDs prepared in this paper could penetrate nude mice skin and has high fluorescence intensity. The penetration was not enough but emission wavelength can be improved through the material improvement. In this paper, a certain basis for QDs using in vivo imaging is provided.ConclusionAgInS2QDs prepared in this study have a lot of advantages, such as simple synthetic method, excellent optical performance and security. AgInS2QDs will have broad application prospects in molecular imaging. |
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