Polyzwitterionic Nanogels for the Controlled and Sustained Delivery of NO and H₂S

Nanomaterials capable of the controlled and sustained release of nitric oxide (NO) and hydrogen sulfide (H 2 S) have broad therapeutic implications. In this research work, we report on polyzwitterionic nanogels (PZNGs) that easily form nitrite and hydrosulfide salts, which act as precursor materials to fix and release these gaseous molecules in a controlled and sustained approach. Nanogels containing NO 2 – and HS – ions as counteranions were synthesized from three different PZNGs by their direct reaction with aqueous NaNO 2 and NaSH. The dynamic light scattering (DLS) data and transmission electron microscopy (TEM) images of the nanogels indicate that every sample possesses a uniform, spherical structure with excellent dispersion. Based on the stability studies conducted, it has been determined that the optimal storage conditions for these nanogels are within the temperature range of 2–25 °C. These nanogels were found to be cytocompatible, suggesting the potential use of these nanogels in biomedical applications. For conversion of NO 2 – to NO and its release from nanogels, CuSO 4, CoSO 4, FeSO 4, CuCl, citric acid (CA), ascorbic acid (AA), and a combination of CA and AA were utilized. H 2 S release from the nanogels was studied with HCl, CA, and AA. The in vitro release profile exhibited a consistent and regulated pattern of NO and H 2 S release, demonstrating a cumulative release of approximately 94–96% within a duration of 96 h. Antimicrobial studies were performed against Escherichia coli and Staphylococcus aureus bacterial strains to establish their suitability as potential antibacterial agents. The encouraging findings demonstrate that the nanogels with the antibacterial properties described here serve as effective carriers to deliver NO and H 2 S.