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Fluorescence Imaging and Photodynamic Inactivation of Bacteria Based on Cationic Cyclometalated Iridium(III) Complexes with Aggregation‐Induced Emission Properties
Author(s) -
Ho PoYu,
Lee SinYing,
Kam Chuen,
Zhu Junfei,
Shan GuoGang,
Hong Yuning,
Wong WaiYeung,
Chen Sijie
Publication year - 2021
Publication title -
advanced healthcare materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.288
H-Index - 90
eISSN - 2192-2659
pISSN - 2192-2640
DOI - 10.1002/adhm.202100706
Subject(s) - fluorescence , iridium , cationic polymerization , chemistry , photochemistry , photosensitizer , photodynamic therapy , reactive oxygen species , absorbance , ligand (biochemistry) , rational design , combinatorial chemistry , materials science , organic chemistry , catalysis , nanotechnology , biochemistry , physics , receptor , chromatography , quantum mechanics
Abstract Antibacterial photodynamic therapy (PDT) is one of the emerging methods for curbing multidrug‐resistant bacterial infections. Effective fluorescent photosensitizers with dual functions of bacteria imaging and PDT applications are highly desirable. In this study, three cationic and heteroleptic cyclometalated Ir(III) complexes with the formula of [Ir(CˆN) 2 (NˆN)][PF 6 ] are prepared and characterized. These Ir(III) complexes named Ir(ppy) 2 bP , Ir(1‐pq) 2 bP, and Ir(2‐pq) 2 bP are comprised of three CˆN ligands (i.e., 2‐phenylpyridine (ppy), 1‐phenylisoquinoline (1‐pq), and 2‐phenylquinoline (2‐pq)) and one NˆN bidentate co‐ligand (bP). The photophysical characterizations demonstrate that these Ir(III) complexes are red‐emitting, aggregation‐induced emission active luminogens. The substitution of phenylpyridine with phenylquinoline isomers in the molecules greatly enhances their UV and visible‐light absorbance as well as the photoinduced reactive oxygen species (ROS) generation ability. All three Ir(III) complexes can stain both Gram‐positive and Gram‐negative bacteria efficiently. Interestingly, even though Ir(1‐pq) 2 bP and Ir(2‐pq) 2 bP are constitutional isomers with very similar structures and similar ROS generation ability in buffer, the former eradicates bacteria much more effectively than the other through white light‐irradiated photodynamic inactivation. This work will provide valuable information on the rational design of Ir(III) complexes for fluorescence imaging and efficient photodynamic inactivation of bacteria.