Thymol-loaded polycaprolactone wet-spun fibers and their ability to suppress bacterial action and chronic wound-associated pro-inflammatory enzymes activity

Chronic wounds (CWs) are labeled as a significant clinical challenge due to their complex treatment, often hindered by bacterial colonization and persistent inflammation. In this study, the potential of wet-spun polycaprolactone (PCL) fibers embedded with thymol (PCL-thy), a natural antibacterial, anti-inflammatory and antioxidant compound, was investigated for the treatment of CWs. The incorporation of thymol within the fiber structure was confirmed through Fourier-transform infrared spectroscopy. Several characterization tests demonstrated the efficient production of PCL fibers, highlighting their homogeneity, good breaking strength (>2 MPa), high elongation capacity (>290 %) and structural stability when exposed to physiological conditions for 28 days (very small mass loss). The antimicrobial efficacy of the fibers was tested against Staphylococcus aureus, Staphylococcus epidermidis, Escherichia coli and Pseudomonas aeruginosa bacteria, commonly associated with wound infections. Thymol was gradually released from the fibers (50-70 % of total release in 20 days), enabling a prolonged action and achieving nearly 100 % antibacterial effectiveness in the first 4-6 h Moreover, PCL-thy fibers demonstrated high antioxidant (reduction above 60 % of 1,1-diphenyl-2-picrylhydrazyl),anti-biofilm forming abilities and pro-inflammatory enzymes inhibition (matrix metalloproteases and myeloperoxidase inhibition > 80 %). Cytotoxicity tests revealed that keratinocytes retained over 80 % of their metabolic activity when in contact with the fibers, with no adverse effects on cellular proliferation. In conclusion, PCL-thy fibers possess the desired qualities for the treatment of CWs, offering a multifaceted and promising solution for wound dressings.