Studies On The Cytotoxicity Of Quantum Dots And Its Application In Cell Labeling

Due to outstanding optical and magnetic properties, quantum dots （QDs） are oneof the attractive nanoparticles, which have been applied extensively in biological andmedical fields. But the traditional organic QDs have poor biocompatibility and hightoxicity. These disadvantages hinder their further applications in relevant fields. Inorder to solve the problems, we carried out the following experiments.The main research contents and results are summarized as follows:（1） In this paper, we first synthesized three kinds of water-soluble nanoparticles:CdTe, CdTe@SiO₂and Mn:ZnSe quantum dots. For CdTe@SiO₂QDs, there is annon-toxic substance-silica shell outside the CdTe core. Mn:ZnSe nanoparticle is akind of novel QDs without heavy metal ions. We evaluated the nanoparticles toxicityqualitatively by observing the morphological changes of human osteoblast-likeMG-63cells and colorimetric3-（4,5-dimethylthiazol-2-yl）-2,5-diphenyl tetrazoliumbromide （MTT） assays were carried out to detect the cell viability quantitatively. Wechose four different incubation times and five QDs concentrations to check thecytotoxicity. The results showed that CdTe nanoparticles with high concentrationscaused cells to die largely. What’s more, the cell viability had an inverse relationshipwith incubation times and QDs concentrations. To the contrast, CdTe@SiO₂and Mn:ZnSe nanoparticles had no obvious effect on cells. For further study, we studied therelation between the cell viability and the total cadmium concentration in cellsthrough graphite furnace atomic absorption spectrometry （GFAAS）. The viability ofcells treated with CdTe@SiO₂nanoparticles was higher than that treated with CdTenanoparticles. We also discovered that the death rate of cells co-incubated with CdTenanoparticles was proportional to the total intracellular cadmium concentrations.（2） We combined goat-anti-mouse IgG and Mn:ZnSe QDs by using cross-linkingagent and regarded this conjugate as a QDs-secondary antibody probe. Then we optimized the probe concentration and reaction time to improve the synthesisefficiency. The probe could bind with primary antibody （mouse anti-human AFP）selectively and further labeled alphafetoprotein （AFP） in HepG2cells successfully. Inaddition, we studied the cytotoxicity of this probe qualitatively and quantitatively.Conclusively, this probe was proved to be an ideal specific tool to indicate theformation of hepatic carcinoma in the early stage.