Antibacterial Polyhydroxyurethane-Gelatin Wound Dressings with In Situ-Generated Silver Nanoparticles or Hyperthermia Induced by Near-Infrared Light Absorption

Polyhydroxyurethane (PHU) with free secondary amine groups was synthesized by reacting poly(ethylene glycol)bis-cyclic carbonate with triethylenetetramine. PHU was mixed with varying amounts of gelatin (GE) and crosslinked by reacting them with either poly(ethylene glycol)glycidyl ether (PEGDE) or 1,4-butanediol diglycidyl ether (BDDE). The tensile strength and fluid handling capacity of the monolayer films obtained from different formulations of PHU, GE, PEGDE, or BDDE were evaluated. To further improve the tensile strength of dressings via increasing the crosslinking of the networks, varying amounts of epoxidized graphene oxide (EGO) were utilized as an auxiliary crosslinking agent. The improved tensile strength of up to 140% was recorded for these samples. Additionally, the membranes containing EGO were able to absorb near-infrared light. The resulting hyperthermia effect (increasing temperature up to about 63 within 15 min) could efficiently kill bacteria (100% killing). The free secondary amine groups on the PHU backbone also reduced the silver ions loaded into the dressings, and resulting silver nanoparticles (Ag NPs) showed acceptable antibacterial activity against E.coli (53% killing) and S.aureus (78% killing). It was also found that the antibacterial activity of AgNPs-containing samples was further improved after incorporating EGO due to the knife-killing effect of EGO nanoplates.