H2S-Releasing Composite: a Gasotransmitter Platform for Potential Biomedical Applications.

Hydrogen sulfide (H2S) is an endogenous gasotransmitter in the human body involved in various physiological functions including cytoprotection, maintaining homeostasis, and regulation of organ development. Therefore, H2S-releasing polymers that can imitate endogenous H2S release can offer great therapeutic potential. Despite decades of research, the use of H2S donors in medical device applications is mostly unexplored largely due to the challenge of the steady H2S release from a suitable polymeric platform that does not compromise the normal cellular functions of the host. In this work, an exogenous H2S release system was developed by integrating sodium sulfide (Na2S), a common H2S donor, into a medical-grade thermoplastic silicone-polycarbonate-urethane polymer, Carbosil 20 80A (hereon as Carbosil), via a facile solvent evaporation technique. The spatial distribution and nature of Na2S in Carbosil were characterized through X-ray diffraction (XRD) spectroscopy and field emission scanning electron microscopy (FESEM) with energy-dispersive spectroscopy (EDS), indicating an amorphous phase shift upon incorporating Na2S in Carbosil. The composite, Na2S-Carbosil, is responsive in physiological conditions, resulting in sustained H2S release measured for 3 h. In vitro cellular responses of 3T3 mouse fibroblasts, human lung epithelial (HLE), and primary human umbilical vein endothelial cells (HUVEC) were investigated. Fibroblast cells showed cell proliferation in 24 h and complete cell migration in 42 h in vitro. The Na2S-Carbosil composites were cytocompatible toward HUVEC and HLE cells. This study provided important in vitro proof of concept that warrants potential use of these H2S-releasing platforms in engineering biomedical devices, tissue engineering, and drug delivery applications.