Bacterial protease-responsive shape memory polymers for infection surveillance and biofilm inhibition in chronic wounds

Abstract

Chronic wound healing is often negatively impacted by infection. Efficient infection assessment is crucial for effective treatment, and biofilm inhibition could improve treatment efficacy. To that end, we developed a bacterial protease-responsive shape memory polymer based on a segmented polyurethane with incorporated poly(glutamic acid) peptide (PU-Pep). Poly(glutamic acid) degrades in response to bacterial proteases to trigger shape recovery of PU-Pep films that are programmed into a secondary shape. These materials have transition temperatures well above body temperature (~60°C), which enables stable storage in temporary shapes after implantation. Synthesized polymers have high shape fixity (~74%-88%), shape recovery (~93%-95%), and cytocompatibility (~100%). Strained PU-Pep samples underwent shape recovery within ≤24 h in response to the V8 enzyme from Staphylococcus aureus (S. aureus, ~50% recovery) and multiple bacteria strains (S. aureus [~40%], Staphylococcus epidermidis [~30%], and Escherichia coli [~25%]), and they had minimal shape change in response to media controls and mammalian cells. Shape recovery of strained PU-Pep samples prevented biofilm formation on the sample surfaces, and resulting attached planktonic bacteria were vulnerable to applied treatments. PU-Pep with physically incorporated antimicrobials simultaneously prevented biofilm formation and killed isolated bacteria. PU-Pep dressings displayed visible shape change and resistance to biofilm formation in in vitro and ex vivo models. In the in vitro model, PU-Pep shape change also disrupted pre-formed biofilm structures. This novel bacterial protease-responsive biomaterial could serve as a wound dressing that changes shape specifically during bacterial colonization to alert clinicians to infection and make biofilm-associated infections easier to treat.

Keywords: bacteria-responsive; biofilm inhibition; chronic wounds; infection assessment; polyurethane; shape memory polymer.