Yang Zi-Shu, Zhu Xiao-Fei, Zhang Jun-Long
Beijing National Laboratory for Molecular Sciences, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, P. R. China.
School of Chemistry and Life Science, Changchun University of Technology, Changchun 130012, China.
ACS Appl Mater Interfaces. 2025 Jun 18;17(24):35221-35229. doi: 10.1021/acsami.5c05977. Epub 2025 Jun 6.
Photon upconversion via triplet-triplet annihilation (TTA-UC) is a promising technology for environmentally responsive sensing, characterized by delayed fluorescence and anti-Stokes shifts. However, it faces quantification challenges due to intensity-based detection limitations, such as fluorophore concentration, excitation source instability, and environmental scattering. To address these issues, we report a time-resolved fluorescence strategy that exploits the intrinsic delayed fluorescence lifetime of TTA-UC systems as a robust, concentration-independent parameter for the quantitative spatiotemporal mapping of environmental stimuli. Using a TTA-UC platform comprising a lutetium(III) porphyrin photosensitizer and a 9,10-bis(2-phenylethynyl)anthracene (BPEA) annihilator, we demonstrate that the TTA-UC lifetime acts as a universal reporter for diverse physicochemical parameters, including temperature, viscosity, analyte concentration, and pH. As a practical demonstration, we engineered nanoparticles encapsulating the pH-responsive Lu(III) porphyrin/BPEA system, which exhibited a linear lifetime-pH correlation (20.5-34.0 μs vs pH 4.0-8.0, > 0.99) enabling real-time and pH monitoring in beverages, spoiling milk, and living cells. Fluorescence lifetime imaging microscopy integration achieved long-lived emission, exceptional photostability, and high environmental contrast, establishing a versatile platform for quantitative sensing in real-world scenarios. This work bridges the gap between TTA-UC photophysics and practical sensing applications, offering a generalizable platform for stimuli-responsive materials design.
通过三重态-三重态湮灭实现的光子上转换（TTA-UC）是一种用于环境响应传感的有前途的技术，其特点是具有延迟荧光和反斯托克斯位移。然而，由于基于强度检测的局限性，如荧光团浓度、激发源不稳定性和环境散射，它面临着定量挑战。为了解决这些问题，我们报告了一种时间分辨荧光策略，该策略利用TTA-UC系统固有的延迟荧光寿命作为一个稳健的、与浓度无关的参数，用于环境刺激的定量时空映射。使用一个由镥（III）卟啉光敏剂和9,10-双（2-苯乙炔基）蒽（BPEA）湮灭剂组成的TTA-UC平台，我们证明TTA-UC寿命可作为多种物理化学参数的通用报告器，包括温度、粘度、分析物浓度和pH值。作为一个实际演示，我们设计了包裹pH响应性镥（III）卟啉/BPEA系统的纳米颗粒，该系统表现出线性的寿命-pH相关性（20.5-34.0微秒对应pH 4.0-8.0，>0.99），能够对饮料、变质牛奶和活细胞进行实时pH监测。荧光寿命成像显微镜集成实现了长寿命发射、出色的光稳定性和高环境对比度，为实际场景中的定量传感建立了一个通用平台。这项工作弥合了TTA-UC光物理与实际传感应用之间的差距，为刺激响应材料设计提供了一个可推广的平台。
