Depletion and Downregulation of Hydrogen Sulfide Using an Activatable Probe for Promoting Photothermal Therapy toward Colorectal Cancers.

Since hydrogen sulfide (H 2 S) is an important endogenous gaseous mediator, therapeutic manipulation of H 2 S is promising for anticancer treatment. In this work, we develop a novel theranostic nanoplatform with H 2 S-specific and photocontrolled synergistic activation for imaging-guided H 2 S depletion and downregulation along with promoted photothermal therapy. Such a nanoplatform is fabricated by integration of a H 2 S-responsive molecule probe that can generate a cystathionine-β-synthase (CBS) inhibitor AOAA and a photothermal transducer into an NIR-light-responsive container. Our nanoplatform can turn on NIR fluorescence specifically in H 2 S-rich cancers, guiding further laser irradiation. Furthermore, prominent conversion of photoenergy into heat guarantees special container melting with controllable AOAA release for H 2 S-level downregulation. This smart regulation of the endogenous H 2 S level amplifies the PTT therapeutic effect, successfully suppressing colorectal tumor in living mice under NIR fluorescence imaging guidance. Thus, we believe that this nanoplatform may provide a powerful tool toward H 2 S-concerned cancer treatment with an optimized diagnostic and therapeutic effect.