Thermosensitive Chitosan-Hyaluronic Acid Hydrogel for Sustained Betamethasone and Levofloxacin Delivery in Corneal Wound Healing.

PURPOSE: This research designed a thermosensitive chitosan-hyaluronic acid (Ch-HA) hydrogel for the dual controlled release of betamethasone and levofloxacin to improve corneal wound healing and inhibit subsequent infections.

METHODS

Ch (2% w/v) and HA (10% w/v) solutions were neutralized with varying concentrations of β-glycerophosphate. The optimal formulation was characterized for gelation time, swelling, degradation, morphology, cytocompatibility, drug release profiles, and antimicrobial activity. In vivo healing was assessed in a rabbit corneal burn model using fluorescein staining, histology, and cytokine analysis.

RESULTS

Hydrogels with 35% β-glycerophosphate provided an 8-minute gelation time, low cytotoxicity, and favorable swelling/degradation profiles. In vitro release kinetics showed a release profile extending over 24 hours, reaching 49.6% for levofloxacin and 30.3% for betamethasone after 24 hours. The dual-loaded hydrogel exhibited effective antibacterial zones against Staphylococcus aureus (17.8 ± 1.5 mm), Escherichia coli (14.2 ± 1.8 mm), and Staphylococcus epidermidis (11.9 ± 0.8 mm). The antibacterial efficacy was comparable with the levofloxacin-only control for S. aureus and E. coli (P > 0.05), although slightly reduced for S. epidermidis (P < 0.05). In vivo, the Ch-HA-35-beta-levo group accelerated re-epithelialization (4.3 ± 0.6 days vs. 7.3 ± 0.6 days in untreated controls; P < 0.01). Histological analysis revealed significantly reduced epithelial thickening (56.5 ± 2.1 µm vs. 72.7 ± 2.1 µm; P < 0.001), and molecular analysis confirmed a significant downregulation of inflammatory markers, showing a 59% reduction in tumor necrosis factor-α and a 54% reduction in interleukin-6 expression (P < 0.05).

CONCLUSIONS

The thermosensitive Ch-HA hydrogel demonstrated promising physicochemical properties, controlled release kinetics, effective antimicrobial efficacy, and accelerated corneal healing, offering a combined therapeutic approach to simultaneously manage inflammation and infection in corneal injuries.

TRANSLATIONAL RELEVANCE: This instillable in situ gelling drug delivery system bridges laboratory innovation with clinical application by providing a sustained-release platform that simultaneously addresses inflammation and infection, offering a convenient once-daily regimen compared with the frequent instillation required by conventional eye drops that may improve patient compliance.