光動力治療為一新興的治療癌症方法，不僅提供良好的治療效果，更能有效的減少副作用產生，然而，光動力治療在發展上一直受限於光敏劑的吸收波長，意即光敏劑能夠吸收之波段的光，其穿透深度不佳，容易被組織吸收，造成應用上的阻礙，因此，本研究透過結合上轉換奈米粒子與兩種光敏劑，從而得以進行穿透度深的雙光動力治療。首先我們合成出核殼上轉換奈米粒子─LiYbF4:Er@LiGdF4，透過披覆二氧化矽殼層將材料轉成親水性質，並將光敏劑Rose Bengal 和Chlorin e6 修飾於上轉換奈米粒子上，隨後以位於第三生物視窗，具有良好穿透深度之1550 nm 雷射作為入射光源，藉由材料之上轉換特性，吸收1550 nm 激發光並釋放可見光，再由兩種光敏劑分別吸收由材料釋放之可見光，經由螢光共振能量轉移(fluorescence resonance energy transfer, FRET)產生活性氧物質(reactive oxygen species, ROS)，利用ROS毒殺癌細胞，進行雙光動治療。

Photodynamic therapy (PDT) has been emerging as a therapeutic modality featuring microtrauma, low toxicity, favorable selectivity and less side effects in tumor treatment. However, the further development of PDT was largely limited by the potency of the photosensitizer. Most conventional photosensitizers used in PDT are excited by ultraviolet to visible (UV-Vis) light, which suffers from poor tissue penetration depth and UV light hazards in patients. Therefore, we utilized the lanthanide doped upconversion nanoparticles (UCNPs)─LiYbF4:Er@LiGdF4 in PDT. Due to the specific property of upconversion, UCNPs are capable of converting near infrared (NIR) light into UV-visible light, which can activate photosensitizers. This is achieved by coating silica shell around the nanoparticles, transferred UCNPs from hydrophobic into hydrophilic. And then modifying photosensitizers, Rose Bengal and Chlorin e6, on the silica matrix. Upon irradiation with 1550 nm laser which is located at third biological window can provide deep penetration for dual photodynamic therapy. The photosensitizer would produce reactive oxygen species (ROS) through fluorescence resonance energy transfer (FRET) inducing tumor cells apoptosis. Notably, the good therapeutic efficiency and less side effects of dual photodynamic therapy imply that it is a potential candidate for clinical application.

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