中文摘要：

通过溶剂热法合成了具有强发光性质的NaYF4：Gd,Yb,Er/PEI上转换纳米颗粒（UCNPs）,其中钆离子的适量掺杂不仅能促进NaYF4从立方到六方相的转变,而且提高了NaYF4：Yb,Er/PEI纳米颗粒的发光强度.通过X射线衍射,扫描电子显微镜（SEM）,发光光谱等表征方法研究了纳米颗粒的形貌、结构及性质.NaYF4：Gd,Yb,Er/PEI具有均一的尺寸,优异的上转换发光及顺磁特性,其在生物医学中具有广阔的应用前景.通过对UCNPs共价修饰光敏剂四（4-羧基苯基）卟啉（T790）和PEG-NH2,制备了多功能的UCNPs-T790-PEG纳米颗粒并初步探讨了其在肿瘤光动力学治疗（PDT）和磁共振成像（MRI）中的应用.

英文摘要：

Strong luminescent NaYF4：Gd,Yb,Er/PEI up-conversion nanoparticles （UCNPs） were first synthesized by a solvothermal method. Doped appropriate amounts of Gd^3＋ ions can promote the transition of NaYF4 from cubic to hexagonal phase, and increase the luminescence intensity of NaYF4：Yb,Er/PEI nanoparticles. X-ray diffraction, scanning electron microscopy （SEM）, luminescence spectroscopy were applied to characterize the UCNPs. The UCNPs exhibited uniform size, excellent＇ green up-conversion photoluminescence, and paramagnetic properties, making them suitable for biological applications. By successively covalently conjugation of photosensitizer tetra （4-carboxyphenyl）porphyrin （T790） and PEG-NH2 on these UCNPs, we prepared multifunctional UCNPs-T790-PEG nanoparticles for Tl-weighted magnetic resonance （MR） image and photodynamic therapy.