Successful preparation of new low-toxic near-infrared Ag2S quantum dots Imagine a routine examination in a hospital: First, drink a liquid containing nanoparticles called "quantum dots", and then the doctor will let you go slowly After passing through a channel, the laser beam scans the whole body. At the other end of the channel, the computer automatically generates a three-dimensional image. Based on these images, the doctor will tell you whether there are tumor cells in your body and the precise location of the tumor cells. These seem to be only seen in science fiction movies like "Special Forces" or "Avatar", but don't be surprised, this may be the "quantum dot" fluorescence imaging detection technology you can enjoy in the near future. So far, there are three main labeling methods for in vivo fluorescence imaging technology: fluorescent protein labeling, fluorescent dye labeling and quantum dot labeling. In comparison, quantum dots, as a new type of nano fluorescent probe, have many advantages such as wide excitation spectrum, narrow fluorescence emission spectrum, adjustable fluorescence spectrum, high quantum yield, high photochemical stability, and not easy to decompose. Due to the different penetration of tissues at different wavelengths, the absorption of near-infrared wavelengths by hemoglobin, fat and water is kept at a relatively low level. Therefore, for in vivo imaging, the choice of fluorescence labeling methods with excitation and emission spectra located in the near-infrared region will facilitate the optical imaging of in vivo, especially the fluorescence imaging of deep tissues (Nature Method, 2005, 2: 12; Science, 2009, 324: 804). Therefore, low biotoxic near-infrared quantum dots are very important for in vivo fluorescence imaging. Recently, the research team of Wang Qiangbin, Suzhou Institute of Nanotechnology and Nanobionics, Chinese Academy of Sciences, prepared for the first time in the world the silver diethyldithiocarbamate (Ag (DDTC)) as a raw material with a uniform size of about 10 nm. Of monodisperse Ag2S near infrared quantum dots. Compared with current near-infrared quantum dots containing elements such as lead, cadmium or mercury, Ag2S quantum dots have the advantage of lower toxicity. The results of spectroscopic studies indicate that under the excitation condition of 785 nm, this Ag2S quantum dot has a fluorescence spectrum with a half-width of only about 21 nm around 1058 nm. In view of the fact that the discovery of the Ag2S quantum dots has important significance for the fluorescence imaging technology of deep tissues in vivo, the results of this research have recently been published in the well-known journal Journal of the American Chemical Society. The research work was supported by the National Natural Science Foundation of China, the International Cooperation Program of the Chinese Academy of Sciences-National Foreign Experts Bureau Innovation Team, and the Suzhou Science and Technology Bureau.
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