一种水溶性稀土上转换荧光纳米探针及其活体荧光成像研究

目的制备一种水溶性稀土上转换荧光纳米探针NaYF4∶Yb3＋/Er3＋,用于动物活体荧光成像。方法采用三氟乙酸盐热分解法合成油溶性稀土上转换荧光纳米探针NaYF4∶Yb3＋/Er3＋,然后选用柠檬酸或L-半胱氨酸作为修饰剂,置于油-水两相中加热到100℃进行配体交换,离心纯化得到水溶性产物。并对所制备的上转换荧光纳米微粒进行X射线衍射测试（XRD）、X射线光电子能谱分析（XPS）、透射电子显微镜及红外和荧光光谱等表征,确定稀土上转换荧光纳米探针的组成、形态及修饰后该纳米探针的性质。最后将修饰后的水溶性稀土上转换荧光纳米探针作为探针应用于小鼠的活体成像。结果制备的稀土上转换荧光纳米探针NaYF4∶Yb3＋/Er3＋为立方相、平均粒径约21.3 nm的多边形结构,分别在540 nm和660 nm处发出荧光。用柠檬酸或L-半胱氨酸修饰后的稀土上转换荧光纳米探针可以稳定地分散在水中;并且修饰后的稀土上转换荧光纳米探针的粒径、晶相及荧光性质没有发生改变;红外光谱表明,该纳米探针的表面成功引入了修饰剂;该荧光纳米探针用于小鼠活体成像荧光信号清晰可见。结论研制出了一种用柠檬酸或L-半胱氨酸表面修饰的、水溶性稀土上转换荧光纳米探针NaYF4∶Yb3＋/Er3＋,表现出了较好的动物活体成像应用前景。

Study on a water-soluble upconversion fluorescent nanoprobe for in vivo fluorescent imaging

Objective To prepare a kind of water-soluble upconversion nanoprobes（UCNPs） NaYF4 ∶ Yb3 ＋/Er3 ＋ for in vivo fluorescent imaging.Methods The hydrophobic rare-earth UCNPs NaYF4∶ Yb3＋/Er3＋were synthesized by thermal decomposition,which was heated in oil-water phase at 100 ℃ for ligand exchange with citric acid or L-cysteine as modification agent.The water soluble products were obtained by centrifugation to remove the impurities.The rare-earth UCNPs were characterized by X-ray powder diffraction（XRD）,X-ray photoelectron spectroscopy（XPS）,transmission electron microscope（TEM）,Fourier-transform infrared spectroscopy and fluorescence spectroscopy were determined the chemical composition,morphology and fluorescent property.Finally,the water-soluble rare-earth UCNPs were used as probes for in vivo fluorescent imaging in mice.Results The prepared nanocrystals NaYF4∶ Yb3＋/Er3＋were cubic phase,with an average size was about 21.3 nm,which showed emission peaks at 540 nm and 660 nm,respectively.The citric acid or L-cysteine modified rare-earth UCNPs NaYF4∶ Yb3＋/Er3＋were stably dispersed in water and no obvious changes were found in nanoparticles size,crystallization state and fluorescence properties of UCNPs after the surface ligand exchange.Fourier-transform infrared spectroscopy showed that the modification agents were successfully introduced onto the surface of nanoparticles,and imaging signal in mice muscle was clearly visible.Conclusion It is demonstrated that citric acid or L-cysteine modified water-soluble rare-earth UCNPs NaYF4∶ Yb3＋/Er3＋have been successfully developed as fluorescent probes,showing high potential for in vivo animal fluorescence imaging.