| Quantum dots (quantum dots, QDs) is a kind of nanomaterials composed of groups Ⅱ-Ⅵ or Ⅲ-Ⅴ elements. In dimension, the diameter of a QD is less than or close to the exciton Bohr radius (diameter less than 10 nm); therefore, it is a tiny dot object and has a quasi-zero-dimensional nanostructure. QDs not only have particular optical and electronic properties with broad absorption and narrow emission ranges, but also possess the quantum confinement effect and the unique surface effect, all of the special function allows QDs can be applied in a variety of industrial and biomedical areas, such as tracking of macromolecules inside cells and tissues and labeling of organelles and cells.Because of QDs’ wide use, they become hot spot and focus for many scientists in different research fields. For a long period of time, science and technology researchers all over the world mainly committed to the study of the toxicity of QDs, the research results indicate that, in addition to the physical and chemical properties of QDs, their toxicity and biological behavior is usually determined by the other three conditions: ①the crystal structure of the metal core;②Surface modification for QDs;③the external environment of QDs, exists in interactions between QDs particles and molecular events from external special surrounding conditions. The toxicity of QDs has also been a major obstacle for QDs’ application in biomedical field. Our topic group previous research shows that, at the range of low exposure concentration, quantum dots are relatively nontoxic, and we also find out the critical point of the toxicity and the safe use, namely the safe dose range of QDs, and provide valuable reference for QDs’ reasonable and safe use. In addition to By reduce the exposure concentration of QDs could result in reducing its toxicity, in this study,we focused on the use of safe exogenous compounds or other exogenous treatment, such as hydrogen sulfide (H2S)/ resveratrol and heat treatment, which could inspire the protection mechanism of organism itself to reduce the toxicity of QDs-apoptosis. Cadmium telluride (CdTe) which is widely applied in current biological research field is used in this research, NIH 3T3 and L929 cells were regard as the research model in vitro for looking for processing method to reduce cytotoxicity caused by CdTe QDs. The main aim of this study was to investigate whether the Resveratrol/H2S and Thermotherapy could protect L929 cells against anti-proliferation effect, ROS formation and apoptosis induced by CdTe QDs in vitro. The potential mechanisms were also explored at the same time.CdTe QDs were regard as object, L929 and NIH 3T3 cells were regard as in vitro experimental research model, and the research mainly explored the effect of H2S/resveratrol and heat treatment on apoptosis mediated by CdTe QDs through conducting a series of experiments, such as MTT assay, Annexin V-FITC/propidium iodide apoptosis assay, Western Blotting and so on. It was also a main purpose of this study to try to use H2S/ resveratrol intervention and heat treatment of which had no physical damage to the biology treatment and could stimulate the organism’s own protection mechanisms to reduce the apoptosis caused by QDs at the same time.In this study, we can primarily draw the conclusion as follows:1. Successful synthesized two different sizes of CdTe by controlling the mixing time of water bath according to electrochemical process. After detection, we found that both sizes of CdTe were spherical, well distribution, have a good fluorescence performance, excellent stability and good water-soluble, and fit our experimental needs.2. L929 and NIH 3T3 cells were administrated 24h with two kinds of CdTe QDs(2.2 nm and 3.5 nm) at the range of 0-80 μg/ml, the expression quantity of phosphorylated protein including P-p38/P-JNK/P-AKT increase which compared with the control protein was statistically significant (P<0.05). The result also showed that three apoptosis related protein P-p38/P-JNK/P-AKT all expressed in a dose-dependent manner. So, CdTe QDs can activate P38-MAPK/JNK-MAPK and AKT signal pathways. In addition, the experiment selected two kinds of cell lines-L929 and the NIH 3T3, the data showed that the expression of the same proteins had no significant difference in different cell lines, that mens the quantum dots can activate three signaling pathways in L929 and NIH 3T3 cells, the activation degree of three pathways is identical. The result suggest that the added of Resveratrol/H2S and Thermotherapy could improve the survival rate. 3. When L929 and NIH 3T3 cells were administrated with 80 μg/ml CdTe QDs (2.2 nm and 3.5 nm) for 12 h, the survival rate declined, intracellular ROS level is much higher than normal control group, the number of apoptotic cells increased significantly, compared with control group without any treatment, was statistically significant (P<0.05). If L929 cells were treated with 400 μmol/L NaHS (the donor of H2S) for 30 min prior to exposure to 80 μg/ml CdTe QDs, the rate of survival increased to (70.5±0.5)% and (74.4±1.2)%, generation of ROS were reduced to (37.58±1.22)% and (32.46±1.03)%, the rate of apoptosis decreased to (39.33±1.23)% and (35.14±0.33)%, respectively. Compared with CdTe QDs group, was statistical significance (P<0.05). When L929 cells were treated with 20 μmol/L Resveratrol and Thermaotherapy at 43℃ for 30 min respectively prior, we get the similar conclusion. There is no difference among three methoods. The date of NIH 3T3 cells showed the similar results.Above all, Resveratrol/H2S and Thermotherapy treatments caused a significant decrease in apoptosis induced by CdTe QDs. demonstrate that the production of ROS were reduced after cells subjected three exogenous treatments. In addition, from the data results NaHS/resveratrol/heat treatment had no obvious effect on ROS levels and surviver rate in the cell, and almost or causes little cells apoptosis, namely, the additionof NaHS/resveratrol and heat treatment will not harm the cells.4. H2S/Thermotherapy and Resveratrol could attenuate apoptosis effect mediated by CdTe QDs of which was closely related with the activation of P38-MAPK, JNK-MAPK and AKT signal pathways. The outcome showed exposure of L929 and NIH 3T3 cells to 80 μg/ml CdTe QDs (2.2 nm and 3.5 nm) for 12 h obviously upregulated the expression of P-p38MAPK/P-JNK and P-AKT, these effects was markedly suppressed by pretreatment of cells with 400 μmol/L NaHS, thermotherapy at 43℃ and 20 μmol/L resveratrol for 30 min before exposure to 80 μg/ml CdTe QDs.These demonstrated that three different treatments could block three pathways effectively. However, pretreatment with 400 μmol/L NaHS, thermotherapy at 43℃ and 20 μmol/L resveratrol had no significant effect on the basal expression of T-p38MAPK/T-JNK and T-AKT protein, the preconditions ensure the compration between phosphorylated proteins was meaningful. Therefore, the regulation of P38-MAPK/JNK-MAPK and AKT signal pathways may be the mechanism of which reduced apoptosis effect by NaHS/Resveratrol and heat treatments, this provides a valuable reference for further discussion in the future experiments for us. |
PDF Full Text Request