Rational Design of Cyclometalated Iridium(III) Complexes for Three-Photon Phosphorescence Bioimaging.
Chengzhi JinFengyin LiangJinquan WangLili WangJiangping LiuXinxing LiaoThomas W ReesBo YuanHui WangYong ShenZhong PeiLiangnian JiHui ChaoPublished in: Angewandte Chemie (International ed. in English) (2020)
Compared to 2PE (two-photon excitation) microscopy, 3PE microscopy has superior spatial resolution, deeper tissue penetration, and less defocused interference. The design of suitable agents with a large Stokes shift, good three-photon absorption (3PA), subcellular targeting, and fluorescence lifetime imaging (FLIM) properties, is challenging. Now, two IrIII complexes (3PAIr1 and 3PAIr2) were developed as efficient three-photon phosphorescence (3PP) agents. Calculations reveal that the introduction of a new group to the molecular scaffold confers a quadruple promotion in three-photon transition probability. Confocal and lifetime imaging of mitochondria using IrIII complexes as 3PP agents is shown. The complexes exhibit low working concentration (50 nm), fast uptake (5 min), and low threshold for three-photon excitation power (0.5 mW at 980 nm). The impressive tissue penetration depth (ca. 450 μm) allowed the 3D imaging and reconstruction of brain vasculature from a living specimen.
Keyphrases
- living cells
- single molecule
- high resolution
- fluorescent probe
- monte carlo
- optical coherence tomography
- room temperature
- energy transfer
- photodynamic therapy
- helicobacter pylori
- high throughput
- quantum dots
- cell death
- high speed
- cancer therapy
- white matter
- helicobacter pylori infection
- molecular dynamics
- resting state
- fluorescence imaging
- subarachnoid hemorrhage
- blood brain barrier
- drug delivery