Investigating biofilm-induced mechanical changes in skin using a biofilm-skin composite model

Wounds are highly susceptible to bacterial biofilm infections, which are difficult to treat and can lead to significant patient morbidity. Microneedles offer a promising strategy for enhancing therapeutic delivery to biofilms, but their interaction on biofilm-affected skin remains poorly understood. In this study, we developed a Pseudomonas aeruginosa biofilm-skin composite model to evaluate time-dependent changes in the mechanical properties of ex vivo porcine skin. Flat punch indentation and single solid microneedle penetration studies were performed for skin exposed to P. aeruginosa over three days to assess the influence of bacterial biofilm maturation on skin mechanics. As the bacterial biofilm matured with increasing bacterial burden, indentation testing revealed progressive changes in the mechanical response of the skin, including increased indenter adhesion to the biofilm-skin composite. Additionally, with increasing incubation time, microneedle puncture experiments demonstrated a decrease in observed punctures, suggesting both increased resistance or altered compliance of the biofilm-skin composite. Collectively, these findings provide a framework for mechanically informed evaluation of biofilm-infected skin that can guide future design of microneedle based and other topical therapeutic strategies for wound infection management.