In situ forming PEG-ε-poly-l-lysine hydrogels with antimicrobial properties for fighting infection

Abstract

Most hydrogel dressings often fail to achieve the required mechanical, antibacterial, and biocompatibility properties simultaneously, which limits their clinical practical application. Therefore, it is urgent to develop a hydrogel dressing that can form in situ to match an irregular wound defect and have antibacterial properties. Herein, we design an in situ forming hydrogel composite of 4-arm-poly(ethylene glycol) succinimidyl (4-PEG-NHS) and ε-poly-L-lysine (PLL). This hydrogel was quickly crosslinked through reaction between the amine groups of PLL and NHS ester group of 4-PEG-NHS under physiological conditions without additional chemical crosslinking agents. Moreover, the hydrogels have inherent antibacterial properties owing to PLL, an antibacterial peptide with broad-spectrum antibacterial activity avoiding bacteria resistance. SEM results showed that the hydrogels have an appropriately interconnected porosity, which facilitates the exchange of nutrients and oxygen with tissues. The swelling results indicated their excellent water absorption and retention capacity, which can not only absorb a large amount of wound exudate but also maintain the wet environment of the wound to accelerate wound repair. The PEG–PLL hydrogels have been found to have excellent antibacterial activity against Gram-positive (S. aureus) and Gram-negative (E. aureus) bacteria in vitro. In an SD rat full-thickness skin defect infection model, the PEG–PLL hydrogels showed a significant antibacterial effect and higher wound closure ratios. Furthermore, the cytotoxicity and hemolytic results indicated that PEG–PLL hydrogels have excellent biocompatibility. In summary, PEG–PLL hydrogels are an ideal wound dressing in clinical work for irregular infected wound repair.