Sulfur Dioxide (SO₂) Releasing Polymeric Systems: Design, Synthesis, and Potential Biomedical Applications

Abstract

In the area of nanomedicines, recently, gasotransmitters have gained much attention as green strategies for various biomedical applications. Sulfur dioxide (SO 2 ), a member of gasotransmitters, has an enormous effect on regulating the structure and function of blood vessels, nervous system, gastrointestinal tract, etc. However, the pharmaceutical use of SO 2 gas has been obstructed due to the administration problem owing to its negligible stability under physiological conditions. In addition, the lack of control delivery at the targeted sites and the toxicity at high concentrations further limit its applications. To date, a wide array of SO 2 -delivering molecules have been designed to address these issues. Despite some success, these small molecular SO 2 donors encounter limitations such as short half-lives, shelf lives, and circulation times. Therefore, fabrications of different SO 2 delivering systems with on-demand release behavior are of serious need for precise delivery. In these contexts, polymeric SO 2 donors have emerged as promising choices due to notable advantages in terms of control release, water solubility, and extremely versatile nature to meet clinical requirements. Herein, we summarize the synthetic strategy and SO 2 release mechanism of recently developed polymeric SO 2 -delivering agents. Additionally, the physiological importance of SO 2 and the advancement of the small molecular SO 2 donors are also discussed. We envisage that this review article will aid researchers in developing potent SO 2 -releasing polymeric systems for paving the way toward the next generation of SO 2 -based gas therapy.