BACKGROUND Biodistribution of photosensitizer (PS) in photodynamic therapy (PDT) can be assessed by fluorescence imaging that visualizes the accumulation of PS in malignant tissue prior to PDT. At the same time, excitation of the PS during an assessment of its biodistribution results in premature photobleaching and can cause toxicity to healthy tissues. Combination of PS with a separate fluorescent moiety, which can be excited apart from PS activation, provides a possibility for fluorescence imaging (FI) guided delivery of PS to cancer site, followed by PDT. RESULTS In this work, we report nanoformulations (NFs) of core-shell polymeric nanoparticles (NPs) co-loaded with PS [2-(1-hexyloxyethyl)-2-devinyl pyropheophorbide-a, HPPH] and near infrared fluorescent organic dyes (NIRFDs) that can be excited in the first or second near-infrared windows of tissue optical transparency (NIR-I, ~ 700-950 nm and NIR-II, ~ 1000-1350 nm), where HPPH does not absorb and emit. After addition to nanoparticle suspensions, PS and NIRFDs are entrapped by the nanoparticle shell of co-polymer of N-isopropylacrylamide and acrylamide [poly(NIPAM-co-AA)], while do not bind with the polystyrene (polySt) core alone. Loading of the NIRFD and PS to the NPs shell precludes aggregation of these hydrophobic molecules in water, preventing fluorescence quenching and reduction of singlet oxygen generation. Moreover, shift of the absorption of NIRFD to longer wavelengths was found to strongly reduce an efficiency of the electronic excitation energy transfer between PS and NIRFD, increasing the efficacy of PDT with PS-NIRFD combination. As a result, use of the NFs of PS and NIR-II NIRFD enables fluorescence imaging guided PDT, as it was shown by confocal microscopy and PDT of the cancer cells in vitro. In vivo studies with subcutaneously tumored mice demonstrated a possibility to image biodistribution of tumor targeted NFs both using HPPH fluorescence with conventional imaging camera sensitive in visible and NIR-I ranges (~ 400-750 nm) and imaging camera for short-wave infrared (SWIR) region (~ 1000-1700 nm), which was recently shown to be beneficial for in vivo optical imaging. CONCLUSIONS A combination of PS with fluorescence in visible and NIR-I spectral ranges and, NIR-II fluorescent dye allowed us to obtain PS nanoformulation promising for see-and-treat PDT guided with visible-NIR-SWIR fluorescence imaging.

中文翻译：

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核壳聚合物纳米粒子与光敏剂和有机染料共同负载，用于在近波和短波红外光谱区域中通过荧光成像引导光动力疗法。

背景技术可以通过荧光成像来评估光动力疗法（PDT）中光敏剂（PS）的生物分布，该荧光成像使PDT之前恶性组织中PS的积累可视化。同时，在PS的生物分布评估过程中激发PS会导致过早的光漂白，并可能对健康组织产生毒性。PS与单独的荧光部分的组合，除了PS活化之外，还可以被激发，这为PS荧光成像（FI）指导将其递送到癌症部位提供了可能性，随后是PDT。结果在这项工作中，我们报道了与PS [2-（1-hexyloxyethyl）-2-devinyl pyropheophorbide-a，一起负载的核壳聚合物纳米颗粒（NPs）的纳米制剂（NFs），HPPH]和近红外荧光有机染料（NIRFD），它们可以在组织光学透明性的第一个或第二个近红外窗口（NIR-I，约700-950 nm和NIR-II，约1000-1350 nm）中被激发， HPPH不会吸收和释放的地方。加入纳米颗粒悬浮液后，PS和NIRFD被N-异丙基丙烯酰胺和丙烯酰胺[poly（NIPAM-co-AA）]共聚物的纳米颗粒壳包裹，而没有单独与聚苯乙烯（polySt）核结合。将NIRFD和PS负载到NPs壳层可防止这些疏水分子在水中聚集，从而防止荧光猝灭和单线态氧生成的减少。此外，发现将NIRFD的吸收转移到更长的波长会大大降低PS和NIRFD之间的电子激发能转移效率，PS-NIRFD组合可提高PDT的功效。结果，使用PS和NIR-II NIRFD的NF可以进行荧光成像引导的PDT，如共聚焦显微镜和体外癌细胞的PDT所示。对皮下肿瘤小鼠的体内研究表明，既可以使用HPPH荧光，也可以使用对可见光和NIR-1范围（〜400-750 nm）敏感的常规成像相机，也可以对短波红外（SWIR）成像相机对肿瘤靶向的NFs的生物分布进行成像。 ）（〜1000-1700 nm）区域，最近被证明对体内光学成像有益。结论PS与可见光和NIR-I光谱范围内的荧光相结合，以及NIR-II荧光染料使我们能够获得PS纳米制剂，有望用于可见光-NIR-SWIR荧光成像指导的透明PDT。