Activated carbon-chitosan hydrogel dressing loaded with LL37 microspheres for the treatment of infected wounds: In vivo antimicrobial and antitoxin assessment.

Wound healing is a complex process which is crucial for recovery. Delayed wound healing which is caused by the presence of pathogens has posed significant clinical implications affecting millions of patients globally. Wounds infection caused by Pseudomonas aeruginosa present significant challenges due to their resistance to multiple antimicrobial drugs. The Gram-negative bacteria secretes endotoxin lipopolysaccharide (LPS), which impede wound healing and may lead to severe complications, including life-threatening sepsis. Previously, our laboratory has successfully developed a new hydrogel containing a synthetic antimicrobial peptide as an alternative therapy to conventional antibiotics. This hydrogel contains LL37 microspheres embedded into activated carbon-chitosan hydrogel (LL37-AC-CS). LL37-AC-CS has shown desirable physicochemical properties as well as promising antimicrobial and antitoxin activities in vitro. This current study has two main objectives. The first is to evaluate the in vivo antimicrobial efficacy of LL37-AC-CS hydrogel in full-thickness rat wounds infected with P. aeruginosa. The second objective is to investigate the antitoxin efficacy on the rat wound models treated with E. coli endotoxins LPS. The wound healing efficacy was assessed in terms of the macroscopic appearance, wound contraction rate, histology, and wound tissue biochemical markers. As a result, the LL37-AC-CS hydrogel exhibited remarkable antimicrobial and antitoxin efficacy as compared to the controls. The wound healing efficacy was evident in increased wound closure rate and decrease in bacterial bioburden, and favourable changes in wound healing biomarkers namely the myeloperoxidase, interleukin-6 and tumour necrosis factor α. The elevation of hydroxyproline levels in the LPS-treated wound model indicates there was collagen synthesis. In conclusion, the results presented in this study have significantly enhanced our comprehension of the LL37-AC-CS hydrogel's potential in wound healing. Specifically, the research highlights its effectiveness in eliminating endotoxins and preventing bacterial growth.