Degradable janus nanofiber dressing with asymmetric wettability for urethral repair and reconstruction

Urethral wound repair is frequently impaired by urine irritation, bacterial contamination, oxidative stress, and fibrotic remodeling, which together increase the risk of urethral stricture. Herein, a degradable Janus nanofiber dressing with asymmetric wettability was constructed by electrospinning as a multifunctional dressing for promoting urethral inner-wall wound healing. Antibacterial and antioxidant carbon dots (AA-CDs) were first synthesized from ascorbic acid, polyethyleneimine, and glutathione through a one-pot hydrothermal method. The AA-CDs were then incorporated into a hydrophilic layer (PLGA@mPEG@AA-CDs), followed by deposition of a hydrophobic layer (PCL) to obtain the PCL/PLGA@mPEG@AA-CDs (PPPC) nanofiber dressing. The inner hydrophobic layer served as a urine-resistant barrier, whereas the outer hydrophilic layer improved wound affinity and provided sustained bioactivity. The optimized PPPC-15 nanofiber dressing showed asymmetric wettability, favorable flexibility, enhanced tensile properties, and gradual degradation in a simulated urethral environment. AA-CDs loading endowed the dressing with efficient antibacterial activity against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli), high cytocompatibility, and strong promotion of epithelial cell migration and tube formation. In a rabbit urethral wound model, PPPC-15 maintained luminal patency, reduced stricture incidence, accelerated urothelial regeneration, enhanced vascularization and smooth muscle reconstruction, and minimized scar-related complications. This Janus nanofiber dressing provides a practical strategy for local urethral wound management and scarless urethral reconstruction.