Stable, Bright, and Long-Fluorescence-Lifetime Dyes for Deep-Near-Infrared Bioimaging

• DOI: 10.1021/jacs.2c05826
• Publication Date: 2022-07-29T20:07:46Z
• Authors: Jin Li; Yan Dong; Ruwei Wei; Guanyu Jiang; Cheng Yao; Meng Lv; Yuyang Wu; Sarah H. Gardner; Feng Zhang; Melissa Y. Lucero; Jian Huang; Hao Chen; Guangbo Ge; Jefferson Chan; Jinquan Chen; Haitao Sun; Xiao Luo; Xuhong Qian; Youjun Yang
• Keywords: Photobleaching; Quantum yield; Triphenylamine

Near-infrared (NIR) fluorophores absorbing maximally in the region beyond 800 nm, i.e., deep-NIR spectral region, are actively sought for biomedical applications. Ideal dyes bright, nontoxic, photostable, biocompatible, and easily derivatized to introduce functionalities (e.g., bioconjugation or aqueous solubility). The rational design of such remains a major challenge. Silicon-substituted rhodamines have been successful bioimaging applications red region. longer-wavelength silicon-substituted congeners unknown date. We successfully prepared four bis-benzannulated rhodamine (ESi5a–ESi5d), with an efficient five-step cascade on gram-scale. Because extensive overlapping their HOMO–LUMO orbitals, ESi5a–ESi5d highly (λabs ≈ 865 nm ε > 105 cm–1 M–1). By restraining both rotational freedom via annulation vibrational silicon-imparted strain, fluorochromic scaffold ESi5 is rigid, resulting unusually long fluorescence lifetime (τ 700 ps CH2Cl2) high quantum yield (ϕ = 0.14 CH2Cl2). Their half-lives toward photobleaching 2 orders magnitude longer than current standard (ICG serum). They stable presence biorelevant concentration nucleophiles reactive oxygen species. minimally toxic readily metabolized. Upon tail vein injection ESi5a (as example), vasculature nude mouse was imaged signal-to-background ratio. broad potentials