镧系离子掺杂的上转换纳米粒子的激发光窗口调控

Lanthanide ion doped upconversion nanoparticles have drawn great interest in the past few years due to their unique properties such as large anti-Stokes shift, high photostability and low toxicity. Particularly, these nanoparticles show great promise in bioapplications such as bioimaging, biosensing and therapy. Typically, the lanthanide doped upconversion nanoparticles are excited by a near infrared light at ~980 nm. However, such narrow excitation window hinders the further applications of lanthanide ion doped upconversion nanoparticles. Moreover, the upconversion efficiency of these nanoparticles is still low which is mainly due to the small absorption cross section. To solve these problems, we here seek new strategies to extend the excitation window of upconversion nanoparticles. The first strategy is to find new lanthanide ions as sensitizers for the exaction of upconversion nanoparticles. Traditional 980 nm excitation is mainly due to the employment of Yb ions as sensitizer. Therefore, we here hope to find other lanthanide ions with different excitation wavelengths as sensitizer. For the second strategy, the conventionally used organic dyes will be combined with the upconversion nanoparticles. Taking advantage of adjustable excitation and large absorption cross section of the organic dyes, the excitation wavelength could be easily engineered and the upconversion emission may be enhanced. Thirdly, we will try to couple the plasmonic materials such as gold and silver to broaden the excitation window and to promote the upconversion emission. Finally, we will utilize these broad band excited upconversion nanoparticle for various applications such as biosensing.

稀土离子掺杂的上转换发光纳米粒子有着独特的性质，比如大的反斯托克斯位移，高光稳定性和低毒性。因此，上转换纳米粒子在过去的几年中引起了极大的研究兴趣，特别是在生物应用方面，比如生物成像，生物传感和治疗。典型的上转换纳米粒子是由~980nm的近红外光激发的，然而，这个狭窄的激发范围妨碍了稀土离子掺杂的上转换纳米粒子的进一步应用。此外，由于较小的吸收截面，这些纳米颗粒的上转换效率仍然很低。在这个项目里，我们尝试寻找新的方法以扩大上转换纳米粒子的激发窗口。我们会设计不同的方法，比如寻找新的稀土离子作为敏化剂，将一些常见的有机染料与上转换纳米颗粒相结合，将等离子共振材料和上转换纳米粒子结合，以达到扩大上转换粒子激发窗口，同时增强上转换发光的目的。最后我们会基于这些上转换纳米粒子发展出一些生物应用，比如生物传感器。

稀土离子掺杂的上转换发光纳米粒子有着如大反斯托克斯位移，高光稳定性和低毒性等独特的性质。然而，典型的上转换纳米粒子还有着如激发范围窄，发光效率低等问题，这些问题妨碍了稀土离子掺杂上转换纳米粒子的进一步应用。本项目中，我们针对上转纳米材料发光效率低的问题，探究了上转换材料发光较弱的原因，采用增强纳米材料吸收和杂离子掺杂等方法，实现了上转换纳米材料发光的有效增强。在此基础上，我们系统总结了调控上转换纳米材料激发窗口的方法，同时对上转换纳米材料的主体材料进行了探索，寻找到了一些新型上转换纳米材料。基于这些基础研究，我们也发展了基于上转换纳米粒子传感器，如水分子、温度传感器等。本项目的研究结果为进一步提高稀土掺杂上转换纳米材料的发光提供了新的思路，也为发展新型上转换纳米材料提供了理论和实验基础，同时这些研究结果将对稀土掺杂上转换纳米材料的应用发展起到推动作用。