与传统的有机光敏剂相比，纳米二氧化钛(TiO2)无机光敏剂具有性能稳定、无毒及体内维持时间长等优点，在恶性肿瘤的光动力治疗(PDT)中具有潜在应用。然而，TiO2需要紫外光或更短波长射线激发，紫外光较差的穿透能力以及对正常组织的损伤限制了其PDT应用。本项目设计并制备近红外光激发、RGD肽偶联的TiO2基无机光敏剂材料(TiO2-NaYF4:Yb/Tm复合纳米粒子)，利用NaYF4:Yb/Tm的紫外上转换发光性质，激发TiO2，实现近红外光激发下TiO2的靶向PDT功能；以人肝癌HepG2细胞以及小鼠肝癌模型为对象，研究980nm激光辐照下无机光敏剂靶向PDT功能的可靠性；采用上海光源的X射线荧光成像技术，构建纳米粒子的细胞摄取剂量与PDT性能的可视化定量表征方法；借助MRI诊断技术监测小鼠肿瘤的PDT效应，阐明PDT原理，为近红外光激发的TiO2基无机光敏剂在临床治疗中的应用提供依据。

Compared with traditional organic photosensitizers, Titanium dioxide (TiO2) nanomaterials are excellent inorganic photosensitizer, and have the characteristics of stability, nontoxicity and long maintain time in body, which could have potential application in photodynamic therapy (PDT) for cancers. However, generally, TiO2 nanoparticles can only be excitateded by ultraviolet lights or shorter wave rays, the bad penetrability in body and the tissue damnification of ultraviolet lights restricted the application of TiO2 in PDT. In this project, an inorganic photosensitizer of TiO2-based nanomaterials (TiO2-NaYF4:Yb/Tm composite nanoparticles) labled with RGD peptide will be designed and synthesized, which could be excitateded by near-infrared laser. Under the excitation of 980 nm near-infrared laser, NaYF4:Yb/Tm nanoparticles emitted ultraviolet light, which could further excitated TiO2 for PDT. Based on HepG2 cells and mouse liver cancers, the targeted PDT reliability of inorganic photosensitizers was investigated. Moreover, using X-ray imaging techniques of Shanghai Synchrotron Radiation Facility, the visualization quantitative relationship between cell uptake dose of nanoparticles and PDT performance was constructed. Finally the PDT effect will be investigated by MRI techniques, and the PDT pinciple will also be illuminated. These results could provide some clues for the clinical applications of the inorganic photosensitizer based on TiO2-NaYF4:Yb/Tm composite nanoparticles excitateded by near-infrared laser.