Recent development of hydrogen sulfide-releasing biomaterials as novel therapies: a narrative review

Hydrogen sulfide (H(2)S) has been reported as an endogenous gasotransmitter that contributes to the modulation of a myriad of biological signalling pathways, which includes maintaining homeostasis in living organisms at physiological concentrations, controlling protein sulfhydration and persulfidation for signalling processes, mediating neurodegeneration, and regulating inflammation and innate immunity, etc. As a result, researchers are actively exploring effective approaches to evaluate the properties and the distribution of H(2)S in vivo. Furthermore, the regulation of the physiological conditions of H(2)S in vivo introduces the opportunity to further study the molecular mechanisms by which H(2)S regulates cellular functions. In recent years, many H(2)S-releasing compounds and biomaterials that can deliver H(2)S to various body systems have been developed to provide sustained and stable H(2)S delivery. Additionally, various designs of these H(2)S-releasing biomaterials have been proposed to aid in the normal conduction of physiological processes, such as cardioprotection and wound healing, by modulating different signalling pathways and cell functionalities. Using biomaterials as a platform to control the delivery of H(2)S introduces the opportunity to fine tune the physiological concentration of H(2)S in vivo, a key to many therapeutic applications. In this review, we highlight recent research works concerning the development and application of H(2)S-releasing biomaterials with a special emphasis to different release triggering conditions in in vivo studies. We believe that the further exploration of the molecular mechanisms underlying H(2)S donors and their function when incorporated with various biomaterials will potentially help us understand the pathophysiological mechanisms of different diseases and assist the development of H(2)S-based therapies.