In recent years, one of main obstacles in a photodynamic therapy (PDT) process has been that most photosensitizers for PDT are excited by visible light with limited penetrating ability; thus most applications of PDT are for superficial treatments. One of the methods to increase the treatment depth is to introduce a two‐photon‐active technique into PDT, known as TP‐PDT. The difficulty here is to obtain photosensitizers with a large enough two‐photon absorption cross‐section. In this work, an organic nanocomplex, composed of the two‐photon nanoaggregate as the core and photosensitizer as the shell, has been constructed. Photosensitizers could be excited indirectly through a fluorescence resonance energy transfer (FRET) mechanism after the two‐photon core was excited by a two‐photon laser. The FRET efficiency was extremely high, owing to sufficient energy donors and stable energy acceptors. In this way, a photosensitizer could induce two‐photon toxicity for improving the treatment depth in PDT. The nanocomplexes were prepared through a molecular assembly method, which avoided complicated reactions for synthesizing two‐photon photosensitizers. The assembly method would expand the selection of photosensitizers and two‐photon dyes, and endow traditional photosensitizers with a larger two‐photon absorption cross‐section for TP‐PDT.

中文翻译：

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组装的纳米复合物，通过粒子内荧光共振能量转移改善光动力疗法

近年来，光动力疗法（PDT）过程的主要障碍之一是大多数PDT的光敏剂被可见光激发而具有有限的穿透能力。因此，PDT的大多数应用是用于表面治疗。增加治疗深度的方法之一是在PDT中引入双光子活性技术，称为TP-PDT。这里的困难是要获得具有足够大的两个光子吸收截面的光敏剂。在这项工作中，构建了一种有机纳米复合物，该复合物由两光子纳米聚集体为核，光敏剂为壳。在双光子核心被双光子激光器激发后，可以通过荧光共振能量转移（FRET）机理间接激发光敏剂。FRET效率极高，由于有足够的能量供体和稳定的能量接受体。通过这种方式，光敏剂可以诱导双光子毒性，从而改善PDT的治疗深度。纳米复合物是通过分子组装方法制备的，避免了合成双光子光敏剂的复杂反应。组装方法将扩大光敏剂和双光子染料的选择范围，并赋予TP-PDT更大的双光子吸收截面的传统光敏剂。