Quantum dots are a new type of nanomaterials with excellent fluorescence properties, and have broad application prospects in the field of biomedicine. However, how to solve the problem of biocompatibility of quantum dots, especially cadmium quantum dots with the highest luminous efficiency, has become a bottleneck in the clinical application of such nanomaterials, and its research has received widespread attention.
The research team of Huang Qing and Fan Chunhai from the Laboratory of Physical Biology, Shanghai Institute of Applied Physics, Chinese Academy of Sciences conducted a systematic study on the cytotoxicity of cadmium quantum dots. The relevant research work has attracted the attention of international peers and was recently invited to the field of biomaterials The famous magazine "Biomaterials" (Biomaterials, 2012, 33, 1238-1244) published a opinion paper (leading opinion paper) The cytotoxicity of cadmium-based quantum dots (cadmium-based quantum dots cytotoxicity). Combined with the latest research results of the research group, the cytotoxicity of cadmium quantum dots and their mechanism of action were systematically discussed, and related research work in this field was summarized and prospected.
The researchers systematically compared the cytotoxicity of three different structures of cadmium quantum dots, and found that CdTe quantum dots have strong cytotoxicity, while the quantum dots wrapped with the core-shell structure have significantly reduced cytotoxicity, especially with a zinc sulfide shell The protected CdTe / CdS / ZnS double-shell quantum dots have almost no obvious toxicity, suggesting that the cytotoxicity of cadmium-based quantum dots is directly related to the concentration of cadmium ions dissociated in the cell (Biomaterials, 2009, 30, 19–25). Further research shows that the cytotoxicity caused by CdTe quantum dots is much higher than that of free cadmium ions at the same concentration. Therefore, it is not enough to consider the cytotoxicity of CdTe quantum dots only from the toxic effects of cadmium ions on heavy metals. This suggests that the size effects and surface effects of nanomaterials may cause so-called "nanotoxicity" (Biomaterials, 2010, 31, 4829-4834).
Subsequently, researchers in the Physics and Biology Laboratory systematically compared the gene expression changes caused by CdTe quantum dots and CdCl2 through the gene chip method, and found that the two have obvious similarities. To reveal this particular nano-effect, the researchers used the advanced soft X-ray cell microscopy (STXM) technology in the Shanghai synchrotron radiation light source to locate the subcellular location of CdTe quantum dot Accurate imaging was performed and it was found that CdTe quantum dots were obviously enriched around the nucleus. Transmission electron microscopy (TEM) results also proved the uneven distribution of CdTe quantum dots in the cell. The heterogeneous distribution pattern of such nanoparticles in the cell produces a significant nano-effect, which causes the concentration of cadmium ions around the nucleus to be much higher than that in other parts of the cell, and the cadmium ions on the surface of CdTe quantum dots that have not been freed may also pass through The direct contact with it produced significant cytotoxicity (Biomaterials, 2012, 33, 1238-1244).
Based on the existing results, the researchers suggest that the cytotoxicity of cadmium-based quantum dots comes from their dissociation or the presence of cadmium ions on the surface, and the distribution of quantum dots in the cells greatly affects their cytotoxicity. This research provides a new mechanism for systematically understanding the biological safety of quantum dots, and is expected to play a guiding role in the application and protection of quantum dots in biological imaging, medical diagnosis and treatment.
Research work on cytotoxicity of cadmium quantum dots
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