Photodynamic therapy (PDT) has achieved great progress in cancer treatment because it generates reactive oxygen species (ROS) in a noninvasive manner. Nonetheless, the majority of light-sensitive photosensitizers (PSs) are only sensitive to UV or visible light, suffering limitations such as phototoxicity (UV) and low tissue penetration capabilities (UV–visible). What is more, another impact factor, namely the hypoxic environment within a tumor always inhibits the production of ROS for treatment efficacy. To overcome these problems, herein, one new type-I PS containing selenium (Se6) is designed. Benefiting from the dual heavy atom effects of selenium and bromine, Se6 can produce short-lived hydroxyl (^•OH) and long-lived superoxide anion (O₂^•−) under both normoxic and hypoxic conditions, which is superior to commonly used oxygen-dependent type-II PSs, such as chlorine e6, zinc phthalocyanine. Combining Se6 and upconversion nanoparticles with the ability to upconvert near-infrared (NIR) light to UV–visible light can greatly overcome the tissue penetration depth, phototoxicity, and oxygen-dependent limitation of the PDT process, which demonstrates a significant performance in vivo to achieve better therapy efficiency.

中文翻译：

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用于增强光动力治疗的 I 型有机光敏剂功能化上转换纳米颗粒

光动力疗法（PDT）因其以非侵入性方式产生活性氧（ROS）而在癌症治疗中取得了巨大进展。尽管如此，大多数光敏光敏剂（PS）仅对紫外线或可见光敏感，存在光毒性（UV）和低组织渗透能力（紫外线-可见光）等局限性。此外，另一个影响因素，即肿瘤内的缺氧环境总是会抑制ROS的产生，从而影响治疗效果。为了克服这些问题，本文设计了一种新型含硒（Se6）的I型PS。得益于硒和溴的双重重原子效应，Se6在常氧和缺氧条件下都能产生短寿命的羟基（^• OH）和长寿命的超氧阴离子（O ₂ ^•−），优于常用的氧-依赖的II型PS，如氯e6、锌酞菁。将Se6和具有将近红外（NIR）光上转换为紫外-可见光能力的上转换纳米颗粒相结合，可以极大地克服PDT过程的组织穿透深度、光毒性和氧依赖性限制，这在体内表现出显着的性能达到更好的治疗效果。