Mitigating enzyme and bacterial functions in diabetic ulcer environments using WAAPV-containing electrospun fibers

Diabetic ulcers are often worsened by elevated levels of human neutrophil elastase (HNE) and bacterial infections, both of which impede healing. To address these challenges, polycaprolactone (PCL)/polyethylene glycol (PEG) electrospun fibers infused with elastase-targeting peptides, AAPV and WAAPV, were engineered. The fibers were designed to exert multiple actions, including the inhibition of HNE. WAAPV's effectiveness in regulating proteolytic enzymes was verified by its ability in inhibiting HNE activity. The incorporation of PEG into the fibers enhanced their wettability, although it also accelerated degradation. However, the inclusion of WAAPV mitigated this effect, resulting in a sustained release of peptides over 24 hours.

Peptide loading within the fibers was confirmed through thermal stability and hydration capacity analyses, and the peptide concentrations were determined by mass/dimension ratios in approximately 51.1 μg/cm² and 46.0 μg/cm² for AAPV, and 48.5 μg/cm² and 51.3 μg/cm² for WAAPV, within PCL and PCL/PEG matrices, respectively. Both peptides effectively inhibited HNE, with PEG showing potential to enhance this inhibition by interacting with the peptides and forming peptide-PEG complexes. The fibers containing PCL and peptides achieved approximately 10% HNE inhibition after 6 hours of incubation, while PCL/PEG fibers showed ≈ 20% inhibition after 4 hours testing.

Peptide-loaded fibers demonstrated significant antibacterial activity, inhibiting the growth of Staphylococcus aureus by up to 78% and Escherichia coli by up to 66%, with peak efficacy observed after 4 and 2 hours of incubation, respectively. These findings suggest that WAAPV-loaded fibers hold promise for inhibiting HNE and bacterial activity, and thus for treating diabetic ulcers.