Smart Nanofibre Dressing Fights Infection Then Repairs Diabetic Wounds in Stages
A coaxial electrospun dressing releases antibiotics rapidly then delivers regenerative peptides over 7 days, tackling diabetic foot ulcers in sequence.
Summary
Researchers at Queen's University Belfast engineered a dual-compartment wound dressing using coaxial electrospinning. The outer PCL shell rapidly releases the antibiotic levofloxacin within hours, while the inner PVA core slowly delivers insulin or CGRP over seven days. This staged approach addresses two competing needs in diabetic foot ulcer care: fast infection clearance and sustained tissue regeneration signalling. In lab tests, the dressing inhibited both Staphylococcus aureus and E. coli for a full week, while peptide payloads were protected from the degradation seen in free-peptide controls. The fibres also showed improved mechanical strength compared to unloaded mats, suggesting the platform is physically robust enough for wound dressing applications.
Detailed Summary
Diabetic foot ulcers (DFUs) are a leading cause of amputation and chronic disability, presenting a dual clinical challenge: infections must be controlled immediately while tissue repair requires sustained biological signalling over days to weeks. Delivering these two types of agents together has been difficult because they have conflicting release requirements and therapeutic peptides are inherently unstable outside a protective matrix.
This in vitro study fabricated a core-sheath nanofibre dressing using coaxial electrospinning. The outer shell was made from poly(ε-caprolactone) (PCL) loaded with levofloxacin (LEV), a broad-spectrum fluoroquinolone antibiotic. The inner core used poly(vinyl alcohol) (PVA) encapsulating either insulin or calcitonin gene-related peptide (CGRP), both of which support wound healing and tissue regeneration.
Encapsulation efficiency exceeded 92% for levofloxacin and approached 83% for both peptides. In simulated physiological conditions, the antibiotic was released rapidly — over 91% within 4 hours — while peptide payloads were released gradually, reaching approximately 88–90% cumulative release over 7 days. Crucially, free peptides in solution showed time-dependent degradation, whereas fibre-encapsulated peptides were measurably more stable. The dressings also maintained antibacterial activity against S. aureus and E. coli throughout the 7-day testing period. Drug loading improved tensile strength, with CGRP-loaded fibres reaching 11.80 MPa versus 7.05 MPa for blank fibres.
The findings demonstrate that a single dressing can decouple the kinetics of antibiotic and regenerative agent delivery, matching the biological timeline of wound healing. This modular platform could reduce the need for multiple wound interventions and improve outcomes in chronic wound management.
Caveats are significant: this is a proof-of-concept in vitro study. No cell culture, animal, or clinical data are included, and translation will require biocompatibility testing, in vivo wound models, and peptide stability assessment under real wound conditions.
Key Findings
- LEV released >91% within 4 hours from PCL shell, providing rapid antibacterial action.
- Insulin and CGRP released steadily over 7 days from PVA core, reaching ~88–90% cumulative release.
- Dressings inhibited S. aureus and E. coli throughout the full 7-day observation period.
- Fibre encapsulation protected peptides from degradation observed in free-peptide controls.
- Drug loading increased tensile strength from 7.05 MPa (blank) to 11.80 MPa (CGRP-loaded).
Methodology
Coaxial electrospinning was used to fabricate PCL/PVA core-sheath nanofibres loaded with levofloxacin (shell) and insulin or CGRP (core). Release profiles were measured in phosphate-buffered saline at 37°C over 7 days, and antibacterial activity was assessed using zone-of-inhibition assays against S. aureus and E. coli. This was a purely in vitro proof-of-concept study with no cell or animal testing.
Study Limitations
The study is in vitro only, with no cell viability, cytotoxicity, or animal wound model data provided. Peptide stability under the complex biochemical environment of a real wound (proteases, exudate, pH variation) was not tested. Clinical translation will require extensive biocompatibility and regulatory evaluation before conclusions about patient benefit can be drawn.
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