Injectable hydrogel incorporated with poly(hexamethylene biguanide) and deep eutectic solvent as linker and highly efficient antibacterial agents for bacteria-infected burnt wound

Minor and severe burn injuries are common and highly complicated pathology causing huge mortality and costly wound treatment protocols. In this work, an injectable microgel assembly was developed to accelerate burn wound healing rate and quality where the network formation occurred after injection of the precursor on the wound bed. Poly(hexamethylene biguanide) (PHMB), an amine-containing antibacterial polymer, was synthesized and functioned as a linker of microgels by the addition of a specific deep eutectic solvent (DES) as a catalyst for particles connection. The major function of the eutectic mixture was to assist in the cross-linking of the microgels; however, it could play as an antibacterial agent against Gram + bacteria. The THDES was prepared by the reaction of arginine with ascorbic acid (Asc), and glycerol ([DES]_Arg/G,A), two of which are known as the components involved in the wound healing process. Depending on the PHMB concentration, the microgel assembly experienced a gel-to-sol transition under shear stresses ranging from 10⁴ to 10⁵ Pa and exhibited much stronger antibacterial activities as the fraction of PHMB increased. Application of the developed hydrogel promoted healing of the infected burned rat, enhanced re-epithelialization, and attenuated the formation of fibrotic scar tissue.