光动力疗法（PDT）是继手术、化疗、放疗后第四种治疗恶性肿瘤的重要方法。传统PDT主要利用可见光激发光敏剂（如酞菁光敏剂）产生单线态氧而杀死肿瘤细胞，存在穿透深度浅、肿瘤靶向性差及无法诊疗一体化等诸多不足。上转换纳米靶向光敏剂充分利用近红外激发下，稀土上转换荧光具有的高组织穿透深度和纳米探针到光敏剂的高效能量传递等优异性能，在对特定肿瘤实现靶向生物检测和成像的同时，同步实现原位PDT。本项目致力于发展适于近红外激发的上转换纳米靶向光敏剂, 通过将对不同肿瘤标志物具有高亲和力的靶向多肽修饰到光敏剂分子上，再将合成的靶向光敏剂与稀土上转换纳米颗粒偶联，研制出系列针对不同肿瘤标志物的上转换纳米靶向酞菁光敏剂，并系统开展细胞和动物水平上的PDT疗效及诊疗一体化研究。预期本项目研制的上转换纳米靶向光敏剂将集肿瘤检测、靶向生物成像和PDT诸多功能于一体，在肿瘤诊疗一体化领域具有重要应用。

Photodynamic therapy (PDT) is the fourth important treatment method for malignant tumors following surgery, chemotherapy and radiotherapy. In traditional PDT, the photosensitizer (such as zinc phthalocyanine, ZnPc) is stimulated by the visible light to generate singlet oxygen and thus kill the tumor cells. The shortcomings of this method include the limited penetration depth, the poor tumor-targeting, and the non-availablity for integrated applications in cancer diagnosis and treatment, etc. Tumor-targeting photosensitizers coupled with upconversion nanoparticles can be stimunated under the near-infrared light with a high tissue penetrate depth and a high efficient energy transmission from the nanoparticles to the photosensitizer. In this way, those photosensitizers can be used for tumor detection and bioimaging, together with PDT in situ. This project will focus on the development of a new-type tumor-targeting photosensitizers coupled with upconversion nanoparticles. First, the photosensitizer will be modified by a series of targeted groups which have high affinities to tumors. Then these modified photosensitizers will be conjugated to the surface of upconversion nanoparticles. Using these tumor-targeting photosensitizers coupled with upconversion nanoparticles, we plan to carry out the PDT study in vitro and in vivo. We expect that some tumor-targeting photosensitizers coupled with upconversion nanoparticles will be developed for integrated applications in cancer diagnosis and treatment.