新型Nd3+敏化的NaMnF3:Yb/Er上转换纳米颗粒的制备及其在深层组织中的成像研究

It is considered that Rare-earth-doped upconversion nanoparticles (UCNPs) have important application in biolabel and bioimaging because of their low biological toxicity, high light penetration depth, high quantum yield, and so on. The conventional upconversion nanoparticles were always irradiated under excitation of 980 nm laser, which was overlapped with the absorption of the water in tissue when these nanoparticles were used in bio application. Besides, it is necessary to use long wave light (> 600 nm) as luminescent probe for deep bioimaging due to the low penetration of short-wave-length light below 600 nm in tissue. So, the effective methods will be suggested in this project. First, the thermal decomposition methods will be developed to synthesize the NaMnF3:Yb/Er nanoparticles and pure red emission will be obtained excited by 980 nm laser by optimizing the process parameters and the concentration of rare earth ions; Meanwhile, the core-shell structured nanoparticles will be synthesized ti enhance the intensity of red emission. Then, the Nd ions will be incorporated into the NaMnF3:Yb/Er nanoparticles to realize the effective upconversion from 800 nm to red light. Finally, the new NaMnF3:Yb/Er nanoparticles will be used to make the bioimage in cell or tissue under excitation of 800 nm laser to investigate the feasibility of application.

稀土掺杂的上转换纳米颗粒由于具有毒性低、穿透性强、量子效率高等特点，被认为可以广泛地应用于生物标定或生物成像等领域。目前常用的上转换纳米颗粒都是在980 nm的激光激发下发光，但是在生物应用时，组织中的水对该波长的光具有很强的吸收；此外，要向在生物体内做深层次的成像分析，需要成像光的波长要达到600 nm以上。针对整两个问题，本项目一方面开发热分解工艺制备NaMnF3：Yb/Er纳米颗粒，并通过优化制备工艺以及掺杂浓度，使其在980 纳米激光激发下发射纯红色荧光；同时，构造核壳结构以增加其红色荧光的强度。另一方面通过合理地引入Nd离子掺杂，使其可在800 nm激光激发下发出高强度的红光。最后，将制备的Nd掺杂NaMnF3：Yb/Er纳米颗粒注射到细胞或组织中，在800 nm激光照射下进行显微成像，研究其应用的可行性。

采用808 nm激发的发射红光的上转换纳米颗粒作为生物成像探针，既可以避免红外光的热效应，还可以增加探针的探测深度。本项目成功地研发了NaMnF3：Yb/Er纳米颗粒，可在980 nm激光激发下发射波长为660 nm的纯红色荧光，同时在该纳米颗粒表面包覆了含Nd元素的壳层，使其可在808 nm激光激发下也发射纯红色荧光，并通过核壳结构的优化，解释了Nd掺杂产生淬灭效应的原因并提出解决方法。通过对其进行表面修饰，该纳米颗粒可以成功地标记到细胞内，在980 nm激光和808 激光家发下都实现了细胞成像。最后，将该纳米颗粒注射到小鼠体内，成像的同时发现，相对于980 nm激光激发，采用808 nm激光激发时其热效应得到了有效的抑制。