高压氧增敏基于新型上转换纳米颗粒的光动力治疗及机制的研究

Photodynamic therapy (PDT)，due to its advantages of minimal invasiveness, high targeting, low toxicity, has been widely used to treat superficial cancers. The limited light penetration depth as well as hypoxia-associated circumstance, either tumor hypoxia or PDT-induced hypoxia due to the consumption of or lack of oxygen, has largely hindered PDT application in deep-seated tumor treatment. Efficient strategies to increase oxygen supply in tumor in order to generate adequate singlet oxygen upon the excitation of photosensitizer using an appropriate light wavelength is highly demanding. Herein, by taking advantages of 808 nm laser and hyperbaric oxygen (HBO), a clinical available facility, we propose new solution: (1) fabrication of an efficient 808 nm-activated PDT platform based on highly-emissive Nd3+-sensitized upconversion nanoparticles (UCNPs); (2) single-band emission centered at 660 nm from UCNPs overlaps with the absorption of Chlorin e6 (Ce6) and detailed investigation will be conducted on energy transfer process between UCNPs and Ce6 with varying oxygen and laser irradiation conditions; (3) in virtue of the increase amount of dissolved oxygen of HBO within tumors, the nanoparticles will release outburst of singlet oxygen species upon 808 nm laser irradiation. In this project, we will decipher the cytotoxic effect of the novel UCNPs in PDT, and demonstrate the principle of how the 808 nm-sensitized UCNPs and HBO affect the PDT. The study aims to provide experimental evident of the modulation of unfavorable tumor microenvironment with the marriage between HBO and NIR-light sensitized UCNPs to overcome the current limitations of cancer photodynamic therapies. It may help develop new clinical cancer treatment tools.

光动力治疗具有侵入性小、选择性高、毒性小等优点，常用于浅表型肿瘤的治疗。但是，光的组织穿透浅、肿瘤组织缺氧导致的光敏剂产生单线态氧(1O2)效率低是深部肿瘤光动力治疗面临的主要挑战。本项目提出基于高压氧增敏新型上转换纳米颗粒光动力治疗的全新策略：(1)利用808 nm光组织穿透深，构建新型的钕上转换纳米颗粒，该纳米颗粒具有发射荧光强度高、荧光光谱单一等优点；(2)着重优化该纳米颗粒发射单波长（660 nm红色）荧光的能力，增强其与光敏剂“二氢卟吩”的荧光共振能量转移效率、提高1O2产率；(3)联合高压氧，改善肿瘤乏氧微环境，进一步提高光敏剂产生1O2效率。利用上述方法，本项目重点探讨新合成纳米颗粒在808 nm激光和高压氧共同作用下的抗肿瘤治疗效果，阐明其在不同氧条件下对肿瘤细胞和肿瘤组织作用机制。该项目最终为光动力治疗在抗肿瘤治疗的应用提供坚实的实验依据，对开发临床新治疗手段提供帮助。

光动力治疗具有侵入性小、选择性高、毒性小等优点，常用于浅表型肿瘤的治疗。但是，光的组织穿透浅、肿瘤组织缺氧导致的光敏剂产生单线态氧(1O2)效率低是深部肿瘤光动力治疗面临的主要挑战。在本项目执行中，我们先后就UCNP构建、光动力治疗和高压氧联合治疗分别调控、优化，通过联合治疗等多种方式治疗肿瘤，获得较好的肿瘤治疗疗效。具体取得的研究成果如下：(1) 构建了新型UCNPs体系，通过精确调节惰性壳层原子配位缺陷的数量，成功实现上转换荧光增强和多色发射。该多色荧光调节行为与层厚无关，能有效应用到其他的镧系基质；（2）缺氧限制了光动力治疗的效果，高压氧在改善肿瘤的缺氧微环境的同时，还可为光动力治疗供氧以产生更多的 ROS，我们用UCNPs@mSiO2-PEG负载玫瑰红结合高压氧进行光动力治疗，极大提高了肿瘤部位 ROS 产生能力，促进胞外基质降解，降低缺氧和促进纳米粒组织穿透，显著提高肿瘤细胞杀伤的效率，该项成果已获得中国发明专利一项;（3）应用光遗传技术，首次实现808 nm近红外光同时激活miniSOG和chrimson双通道光敏蛋白，通过单线态氧的产生和胞内Ca2+协同，显著提高了近红外光诱导的神经元消融效率，实现了深部组织神经元功能的鉴定。该结果为近红外光介导的高效、精准基于光动力消融细胞提供了快速的平台，为精准肿瘤治疗提供指导。