Donor and Ring-Fusing Engineering for Far-Red to Near-Infrared Triphenylpyrylium Fluorophores with Enhanced Fluorescence Performance for Sensing and Imaging |
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Authors: | Si-Yu Wen Wei Zhang Tian-Bing Ren Qian-Ling Zhang Yu-Peng Liu Ling Shi Prof Rongfeng Hu Prof Dr Xiao-Bing Zhang Prof Dr Lin Yuan |
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Institution: | 1. State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha, Hunan, 410082 P.R. China;2. Key Laboratory of Xin'an Medicine, Ministry of Education, Anhui Province Key Laboratory of Chinese Medicinal Formula, Anhui University of Chinese Medicine, Hefei, Anhui, 230038 P.R. China |
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Abstract: | Fluorescent probes have become an indispensable tool in the detection and imaging of biological and disease-related analytes due to their sensitivity and technical simplicity. In particular, fluorescent probes with far-red to near-infrared (FR-NIR) emissions are very attractive for biomedical applications. However, many available FR-NIR fluorophores suffer from small Stokes shifts and sometimes low quantum yields, resulting in self-quenching and low contrast. In this work, we describe the rational design and engineering of FR-NIR 2,4,6-triphenylpyrylium-based fluorophores ( TPP-Fluors ) with the help of theoretical calculations. Our strategy is based on the appending of electron-donating substituents and fusing groups onto 2,4,6-triphenylpyrylium. In contrast to the parent TPP with short emission wavelength, weak quantum yields, and low chemical stability, the obtained novel TPP-Fluors display some favorable properties, such as long-wavelength emission, large Stokes shifts, moderate to high quantum yields, and chemical stability. TPP-Fluors demonstrate their biological value as mitochondria-specific labeling reagents due to their inherently positive nature. In addition, TPP-Fluors can also be applied to develop ratiometric fluorescent probes, as the electron-donating ability of the 2,6-phenyl substituents is closely correlated with their emission wavelength. A proof-of-concept ratiometric probe has been developed by derivatizing the amino groups of TPP-Fluor for the detection and imaging of nitroreductase in vitro and in hypoxic cells. |
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Keywords: | density functional calculations fluorescent probes fluorophores imaging agents structure–photophysical property relationships |
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