Abstract:
Surgical site infections (SSIs) caused by pathogenic bacteria lead to delayed wound healing, extended hospital stay, and thus, create a burden in healthcare. The overuse and misuse of antibiotics in modern times have caused a surge in SSI in a hospital setting and commonly available antibiotics are proving to be ineffective against them. Antimicrobial peptides (AMPs) can be a potential solution to prevent SSI and accelerate wound healing because of their broad spectrum of antimicrobial activities. Therefore, AMPs were extracted from natural sources and incorporated onto an engineered microfiber to be used as surgical suture. To accomplish this, two polymers of opposite characteristics — a hydrophilic polymer sodium alginate (SA) and a hydrophobic one polycaprolactone (PCL), were used to manufacture microfibers via a novel wet-spinning method. Wet-spinning of PCL and SA is difficult because of their immiscibilities and tendencies to create a complex gelation upon mixing. To circumvent this problem, PCL solution in acetone was dissolved in a SA aqueous solution. The polymer solutions acted as coagulants for each other when PCL molecules encapsulated SA molecules via hydrogen bonding. AMPs were then immobilized onto the fibers exploiting the self-polymerization behavior of dopamine. FTIR results confirmed the successful integration of both polymers and peptides. Conjugation between PCL and SA resulted in fiber with a smooth surface improving the crystallinity and mechanical strength of the fibers via hydrogen bond. Having an average diameter of 220 µm, the mechanical properties of the fiber complied with USP standards for suture of size 3-0. Due to the antibacterial activity of AMP, the microfibers were able to hinder the growth of Proteus spp., a pathogenic bacterium for at least 60 hours which was not the case when the antibiotic ceftazidime was used against it. Attachment of Proteus spp. on fiber surface was also significantly hindered compared to Vicryl, a
commercial suture as found by the direct contact response study. When subjected to in vivo study, accelerated wound healing was observed when the wound was closed using the engineered fiber compared to commercial suture Vicryl. Traces of wounds were observed from dermoscopic images even after 14 days in all cases except for PCL-SA-pep. Histological results revealed the superior wound regeneration ability of the manufactured fiber. PCL-SA-pep fiber promoted faster re- epithelialization in just 3 days as characterized by a continual decrease in epithelial gap in the wound, did not elicit much inflammatory reactions, and reduced scar area. Neoangiogenesis and growth of follicular structures were also observed to be significantly higher in PCL-SA-pep treated wounds compared to Vicryl proving the higher wound healing capacity of the engineered microfiber.
