Fluorescence (FL) bioimaging in the second near-infrared window (NIR-II, 1000–1700 nm) provides improved imaging quality and high resolution for diagnosis of deep-seated tumors. However, integrating FL bioimaging and photothermal therapy (PTT) in a single photoactive molecule exhibits a great challenge because a dramatic increase of PTT in the NIR-II window benefitting from the nonradiative decay will sacrifice the fluorescence brightness that is unfavorable for FL bioimaging. Therefore, balancing the radiative decay and nonradiative decay is an effective and rational design strategy. Herein, four NIR-II xanthene dyes (CL1–CL4) are synthesized with maximal emission beyond 1200 nm under 1064 nm excitation. CL4 exhibits the largest fluorescence quantum yield and a significant fluorescence enhancement after complexation with fetal bovine serum (FBS). As-prepared CL4/FBS has a maximal emission of 1235 nm and a high photothermal conversion efficiency of 36% under 1064 nm excitation. Bright and refined tumor vessels with a fine resolution of 0.23 mm can be clearly distinguished by CL4/FBS. In vivo studies show that a balanced utilization of fluorescence and photothermy in the NIR-II window is successfully achieved with superior biocompatibility. This efficient strategy provides promising avenue for precise theranostics of deep tumors.

中文翻译：

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用于高效肿瘤血管造影和光热治疗的 NIR-II 发射超过 1200 nm 的新型呫吨染料

第二近红外窗口（NIR-II，1000-1700 nm）中的荧光 (FL) 生物成像为诊断深部肿瘤提供了改进的成像质量和高分辨率。然而，将 FL 生物成像和光热疗法 (PTT) 集成到单个光活性分子中表现出巨大的挑战，因为受益于非辐射衰减的 NIR-II 窗口中 PTT 的急剧增加将牺牲不利于 FL 生物成像的荧光亮度。因此，平衡辐射衰变和非辐射衰变是一种有效且合理的设计策略。在此，合成了四种 NIR-II 呫吨染料 ( CL1 – CL4 )，在 1064 nm 激发下具有超过 1200 nm 的最大发射。CL4与胎牛血清（FBS）络合后，荧光量子产率最大，荧光增强显着。所制备的CL4 /FBS 在 1064 nm 激发下具有 1235 nm 的最大发射和 36% 的高光热转换效率。CL4 /FBS可清晰区分明亮精细的肿瘤血管，分辨率为 0.23 mm 。体内研究表明，NIR-II 窗口中荧光和光热的平衡利用已成功实现，具有出色的生物相容性。这种有效的策略为深部肿瘤的精确治疗学提供了有希望的途径。