A Tunable Hydrogel Platform Based on Platinum-Containing Polymeric Arsenicals

Platinum and arsenic (e.g., cisplatin, As₂O₃) have been used extensively in modern medicine due to their strong anticancer and antimicrobial activities. Here, polymeric arsenical scaffolds with varying As-functionalized acrylamide monomer (AsAm) composition are combined with Pt^II giving rise to hydrogels (P1-Pt–P4-Pt) with their properties being dependent on the AsAm content. The nature of the Pt–polymer interaction has been thoroughly investigated by ¹H and ¹⁹⁵Pt NMR spectroscopy as well as FT-IR, SEM, XPS, and potentiometric titration suggesting that cross-linking occurs primarily via coordination between oxygen atoms of the pendant arsenic acid group and Pt^II, while secondary noncovalent interactions are proposed to provide further structural integrity and stability. Importantly, the hydrogels demonstrate potential self-healing properties, while the nature of the cross-linking promotes deep penetration of water into the loosely cross-linked networks. Finally, preliminary qualitative antimicrobial evaluation conducted via disk diffusion assay indicates that P4-Pt is active against Gram-negative (uropathogenic Escherichia coli CFT073 and Escherichia coli K12MG1655) and Gram-positive (Bacillus subtilis and Staphylococcus aureus USA 300 JE2) bacterial strains. Overall, the combination of polymeric arsenical scaffolds with Pt^II results in the formation of cross-linked networks generating soft, strong, and self-healing hydrogels with tunable stiffness and elasticity and preliminary indications of antimicrobial potential.