Dual Burst and Sustained Release of p‑Coumaric Acid from Shape Memory Polymer Foams for Polymicrobial Infection Prevention in Trauma-Related Hemorrhagic Wounds

Hemorrhage is the primary cause of trauma-related death. Of patients that survive, polymicrobial infection occurs in 39% of traumatic wounds within a week of injury. Moreover, traumatic wounds are susceptible to hospital-acquired and drug-resistant bacterial infections. Thus, hemostatic dressings with antimicrobial properties could reduce morbidity and mortality to enhance traumatic wound healing. To that end, p-coumaric acid (PCA) was incorporated into hemostatic shape memory polymer foams by two mechanisms (chemical and physical) to produce dual PCA (DPCA) foams. DPCA foams demonstrated excellent antimicrobial and antibiofilm properties against native Escherichia coli, Staphylococcus aureus, and Staphylococcus epidermidis; co-cultures of E. coli and S. aureus; and drug-resistant S. aureus and S. epidermidis at short (1 h) and long (7 days) time points. Resistance against biofilm formation on the sample surfaces was also observed. In ex vivo experiments in a porcine skin wound model, DPCA foams exhibited similarly high antimicrobial properties as those observed in vitro, indicating that PCA was released from the DPCA foam to successfully inhibit bacterial growth. DPCA foams consistently showed improved antimicrobial properties relative to those of clinical control foams containing silver nanoparticles (AgNPs) against single and mixed species bacteria, single and mixed species biofilms, and bacteria in the ex vivo wound model. This system could allow for physically incorporated PCA to first be released into traumatic wounds directly after application for instant wound disinfection. Then, more tightly tethered PCA can be continuously released into the wound for up to 7 days to kill additional bacteria and protect against biofilms.