Cell-Membrane Coated Self-Immolative Poly(thiourethane) for Cysteine/Homocysteine-Triggered Intracellular H 2 S Delivery.

Hydrogen sulfide (H 2 S) is an important gaseous signaling molecule with unique pleiotropic pharmacological effects, but may be limited for clinical translation due to the lack of a reliable delivery form that delivers exogenous H 2 S to cells at action site with precisely controlled dosage. Herein, we report the design of a poly(thiourethane) (PTU) self-immolative polymer terminally caged with an acrylate moiety to trigger release of H 2 S in response to cysteine (Cys) and homocysteine (Hcy), the most used and independent indicators of neurodegenerative diseases. The synthesized PTU polymer was then coated with the red-blood-cell (RBC) membrane in the presence of solubilizing agent to self-assemble into nanoparticles with enhanced stability and cytocompatibility. The Hcy/Cys mediated addition/cyclization chemistry actuated the biomimetic polymeric nanoparticles to disintegrate into carbonyl sulfide (COS), and finally convert into H 2 S via the ubiquitous carbonic anhydrase (CA). H 2 S released in a controlled manner exhibited a strong antioxidant ability to resist Alzheimer's disease (AD)-related oxidative stress factors in BV-2 cells, a neurodegenerative disease model in vitro. Thus, this work may provide an effective strategy to construct H 2 S donors that can degrade in response to a specific pathological microenvironment for the treatment of neurodegenerative diseases.