Poly(ethylene glycol)-Based Hyperbranched Polymer from RAFT and Its Application as a Silver-Sulfadiazine-Loaded Antibacterial Hydrogel in Wound Care

A multifunctional branched copolymer was synthesized by Reversible Addition–Fragmentation Chain Transfer polymerization (RAFT) of poly(ethylene glycol) diacrylate (PEGDA M n = 575) and poly(ethylene glycol) methyl methacrylate (PEGMEMA M n = 500) at a feed molar ratio of 50:50. Proton nuclear magnetic resonance spectroscopy ( 1 H NMR) confirmed a hyperbranched molecular structure and a high degree of vinyl functionality. An in situ cross-linkable hydrogel system was generated via a “click” thiol–ene-type Michael addition reaction of vinyl functional groups from this PEGDA/PEGMEMA copolymer system in combination with thiol-modified hyaluronic acid. Furthermore, encapsulation of antimicrobial silver sulfadiazine (SSD) into the copolymer system was conducted to create an advanced antimicrobial wound care dressing. This hydrogel demonstrated a sustained antibacterial activity against the bacterial strains Staphylococcus aureus, Pseudomonas aeruginosa, and Escherichia coli in comparison to the direct topical application of SSD. In addition, in vitro toxicology evaluations demonstrated that this hydrogel—with low concentrations of encapsulated SSD—supported the survival of embedded human adipose derived stem cells (hADSCs) and inhibited growth of the aforementioned pathogens. Here we demonstrate that this hydrogel encapsulated with a low concentration (1.0% w/v) of SSD can be utilized as a carrier system for stem cells with the ability to inhibit growth of pathogens and without adverse effects on hADSCs.