Intelligent polymeric hydrogen sulfide delivery systems for therapeutic applications

Hydrogen sulfide (H2S) plays an important role in regulating various pathological processes such as protecting mammalian cell from harmful injuries, promoting tissue regeneration, and regulating the process of various diseases caused by physiological disorders. Studies have revealed that the physiological effects of H2S are highly associated with its concentrations. At relatively low concentration, H2S shows beneficial functions. However, long-time and high-dose donation of H2S would inhibit regular biological process, resulting in cell dysfunction and apoptosis. To regulate the dosage of H2S delivery for precision medicine, H2S delivery systems with intelligent characteristics were developed and a variety of biocompatibility polymers have been utilized to establish intelligent polymeric H2S delivery systems, with the abilities to specifically target the lesions, smartly respond to pathological microenvironments, as well as real-timely monitor H2S delivery and lesion conditions by incorporating imaging-capable moieties. In this review, we focus on the design, preparation, and therapeutic applications of intelligent polymeric H2S delivery systems in cardiovascular therapy, inflammatory therapy, tissue regenerative therapy, cancer therapy and bacteria-associated therapy. Strategies for precise H2S therapies especially imaging-guided H2S theranostics are highlighted. Since H2S donors with stimuli-responsive characters are vital components for establishing intelligent H2S delivery systems, the development of H2S donors is also briefly introduced.