Fluorescence imaging in the second near-infrared (NIR-II, 1000–1700 nm) window has exhibited advantages of high optical resolution at deeper penetration (ca. 5–20 mm) in bio-tissues owing to the reduced photon scattering, absorption and tissue autofluorescence. However, the non-responsive and “always on” sensors lack the ability of selective imaging of lesion areas, leading to the low signal-to-background ratio (SBR) and poor sensitivity during bio-detection. In contrast, activatable sensors show signal variation in fluorescence intensity, spectral wavelength and fluorescence lifetime after responding to the micro-environment stimuli, leading to the high detection sensitivity and reliability in bio-sensing. This minireview summarizes the design and detection ability of recently reported NIR-II activatable sensors. Furthermore, the challenges, opportunities and prospects of NIR-II activatable bio-sensing are also discussed.

中文翻译：

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用于在第二近红外窗口中进行体内生物检测的可激活荧光传感器

第二近红外（NIR-II，1000-1700 nm）窗口中的荧光成像在更深的穿透下表现出高光学分辨率的优势（ca.由于光子散射、吸收和组织自发荧光减少，生物组织中的 5-20 毫米）。然而，无响应和“始终开启”的传感器缺乏对病变区域进行选择性成像的能力，导致生物检测过程中信噪比 (SBR) 低和灵敏度差。相比之下，可激活传感器在响应微环境刺激后显示出荧光强度、光谱波长和荧光寿命的信号变化，从而导致生物传感的高检测灵敏度和可靠性。本综述总结了最近报道的 NIR-II 可激活传感器的设计和检测能力。此外，还讨论了 NIR-II 可激活生物传感的挑战、机遇和前景。