Whole-body and whole-organ 3D imaging of hypoxia using activatable covalent fluorescent probe compatible with tissue clearing

Elucidation of biological phenomena requires imaging of microenvironments in vivo. Although the seamless visualization of in vivo hypoxia from the level of whole-body to single-cell has a great potential to discover unknown phenomena in biological and medical fields, no methodology for achieving it has been established thus far. Here, we for the first time report the whole-body and whole-organ imaging of hypoxia, an important microenvironment, at single-cell resolution using activatable covalent fluorescent probes compatible with tissue clearing. We initially focused on overcoming the incompatibility of fluorescent dyes and refractive index matching solutions (RIMSs), which has greatly hindered the development of fluorescent molecular probes in the field of tissue clearing. The fluorescent dyes compatible with RIMS were then incorporated into the development of activatable covalent fluorescent probes for hypoxia. We combined the probes with tissue clearing, achieving comprehensive single-cell-resolution imaging of hypoxia in a whole mouse body and whole organs.