1e:T47c,Fluorescence imaging of tissues offer an essential means for studying biological systems. Autofluorescence becomes a serious issue in tissue imaging under excitation at UV-vis wavelengths where biological molecules compete with the fluorophore. To address this critical issue, a novel class of fluorophores that can be excited at ∼900 nm under two-photon excitation conditions and emits in the red wavelength region (≥600 nm) has been disclosed. The new π-extended dipolar dye system shows several advantageous features including minimal autofluorescence in tissue imaging and pronounced solvent-sensitive emission behavior, compared with a widely used two-photon absorbing dye, acedan. As an important application of the new dye system, one of the dyes was developed into a fluorescent probe for amyloid-β plaques, a key biomarker of Alzheimer's disease. The probe enabled in vivo imaging of amyloid-β plaques in a disease-model mouse, with negligible background signal. The new dye system has great potential for the development of other types of two-photon fluorescent probes and tags for imaging of tissues with minimal autofluorescence.1f:T44d,Hydrogen sulfide (H₂ S) exhibits promising protective effects in many (patho)physiological processes, as evidenced by recent reports using synthetic H₂ S donors in different biological models. Herein, we report the design and evaluation of compounds denoted PeroxyTCM, which are the first class of reactive oxygen species (ROS)-triggered H₂ S donors. These donors are engineered to release carbonyl sulfide (COS) upon activation, which is quickly hydrolyzed to H₂ S by the ubiquitous enzyme carbonic anhydrase (CA). The donors are stable in aqueous solution and do not release H₂ S until triggered by ROS, such as hydrogen peroxide (H₂ O₂ ), superoxide (O₂^- ), and peroxynitrite (ONOO^- ). We demonstrate ROS-triggered H₂ S donation in live cells and also demonstrate that PeroxyTCM-1 provides protection against H₂ O₂ -induced oxidative damage, suggesting potential future applications of PeroxyTCM and similar scaffolds in H₂ S-related therapies.20:T64e,

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