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Enlarging the Reservoir: High Absorption Coefficient Dyes Enable Synergetic Near Infrared‐II Fluorescence Imaging and Near Infrared‐I Photothermal Therapy
Author(s) -
Li Yuanyuan,
Zhang Jianquan,
Liu Shunjie,
Zhang Chen,
Chuah Clarence,
Tang Youhong,
Kwok Ryan T. K.,
Lam Jacky W. Y.,
Ou Hanlin,
Ding Dan,
Tang Ben Zhong
Publication year - 2021
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/adfm.202102213
Subject(s) - photothermal therapy , materials science , molar absorptivity , fluorescence , absorption (acoustics) , near infrared spectroscopy , triphenylamine , quantum yield , conjugated system , photochemistry , optoelectronics , nanotechnology , polymer , optics , chemistry , composite material , physics
Abstract Although organic materials with near infrared (NIR)‐II fluorescence and a photothermal effect have been widely investigated for the accurate diagnosis and treatment of tumors, optimizing the output signals of both remain challenging. Here, a strategy by “enlarging absorption reservoir” to address this issue, since an increase in photon absorption can naturally enhance output signals, is proposed. As a proof‐of‐concept, a large π‐conjugated diketopyrrolopyrrole (DPP) unit is selected to fabricate strong light‐absorbing systems. To enhance solid‐state fluorescence, highly twisted alkylthiophene–benzobisthiadiazole–alkylthiophene and triphenylamine rotor are introduced to restrict the strong intermolecular π–π interactions. Moreover, the number of DPP units in molecules is engineered to optimize photophysical properties. Results show that TDADT with two DPP units possesses an exceptionally high molar absorptivity of 2.1 × 10 5 L mol −1 cm −1 at 808 nm, an acceptable NIR‐II quantum yield of 0.1% (emission peak at 1270 nm), and a sizeable photothermal conversion efficiency of 60.4%. The excellent photophysical properties of the TDADT nanoparticles are particularly suitable for in vivo NIR‐II imaging‐guided cancer surgery and NIR‐I photothermal therapy. The presented strategy provides a new approach of designing highly efficient NIR‐II phototheranostic agents.