Photodynamic therapy (PDT), as a noninvasive therapeutic method, has been actively explored recently for cancer treatment. However, owing to the weak absorption in the optically transparent windows of biological tissues, most commercial photosensitizers (PSs) exhibit low singlet oxygen (¹O₂) quantum yields when excited by light within this window. Finding the best way to boost ¹O₂ production for clinical applications using light sources within this window is, thus, a great challenge. Herein, we tackle this problem using plasmon resonance energy transfer (PRET) from plasmonic nanoparticles (NPs) to PSs and demonstrate that the formation of plasmon quenching dips is an effective way to enhance ¹O₂ generation. The combination of the photosensitizer chlorin e6 (Ce6) and gold nanorods (AuNR) was employed as a model system. We observed a clear quenching dip in the longitudinal surface plasmon resonance (LSPR) band of the AuNRs when the LSPR band overlaps with the Q band of Ce6 and the spacing between Ce6 and the rods is within the acting distance of PRET. Upon irradiation with 660 nm continuous-wave laser light, we obtained a seven-fold enhancement in the ¹O₂ signal intensity compared with that of a non-PRET sample, as determined using the ¹O₂ electron spin resonance probe 2,2,6,6-tetramethyl-4-piperidine (TEMP). Furthermore, we demonstrated that the PRET effect is more efficient in enhancing ¹O₂ yield than the often-employed local field enhancement effect. The effectiveness of PRET is further extended to the in vitro level. Considering the flexibility in manipulating the localized SPR properties of plasmonic nanoparticles/nanostructures, our findings suggest that PRET-based strategies may be a general way to overcome the deficiency of most commercial organic PSs in biological optically transparent windows and promote their applications in clinical tumor treatments.

中文翻译：

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在二氢卟酚e6–金纳米棒偶联系统中，等离激元猝灭浸蚀的形成大大增强了1 O 2的产生

光动力疗法（PDT），作为一种非侵入性的治疗方法，最近已被积极地探索用于癌症治疗。但是，由于在生物组织的光学透明窗口中吸收较弱，因此大多数商用光敏剂（PSs）在该窗口中被光激发时均显示出较低的单重态氧（¹ O ₂）量子产率。因此，找到在该窗口内使用光源提高临床应用中¹ O ₂产量的最佳方法是一个巨大的挑战。本文中，我们使用了从等离激元纳米粒子（NPs）到PSs的等离振子共振能量转移（PRET）解决了这一问题，并证明了形成等离激元猝灭浸液是增强¹ O ₂的有效方法一代。光敏剂二氢卟酚e6（Ce6）和金纳米棒（AuNR）的组合用作模型系统。当LSPR谱带与Ce6的Q谱带重叠并且Ce6与棒之间的间隔在PRET的作用距离之内时，我们观察到AuNRs的纵向表面等离子体激元共振（LSPR）谱带出现明显的淬灭。用¹ O ₂电子自旋共振探针2,2测得，用660 nm连续波激光照射后，与非PRET样品相比，我们的¹ O ₂信号强度提高了7倍， 6,6-四甲基-4-哌啶（TEMP）。此外，我们证明了PRET效应可以更有效地增强¹ O₂产量高于经常使用的局部田间改良效果。PRET的有效性进一步扩展到了体外水平。考虑到操纵等离子纳米颗粒/纳米结构的局部SPR特性的灵活性，我们的研究结果表明，基于PRET的策略可能是克服大多数商业有机PS在生物光学透明窗口中不足并促进其在临床肿瘤治疗中的应用的一般方法。 。