“Turn-On” NIR-II Fluorescence of a Dually Quenched Probe for Sensitive Imaging of Cathepsin B In Vivo

We designed a NIR-II fluorescence probe, Cys(StBu)-Gly-Phe-Leu-Gly-Lys(AF3)-CBT ( AF3-CBT ), which forms dually quenched nanoparticle AF3-NP . Under CTSB cleavage, NIR-II fluorescence turns “On” for sensitive imaging CTSB. AF3-NP showed 6.1-fold, 3.2-fold, and...