Calcium carbonate modified polyurethane shell in polycaprolactone based core-shell fibre integrated 5-fluorouracil delivery for colon treatment: In vitro characterization

Core-shell nanofibers fabricated by coaxial electrospinning offer a versatile platform where the drug is encapsulated within the core fiber for controlled and targeted delivery applications. In this work, polyurethane (TPU)/polycaprolactone (PCL) core-shell nanofibers were developed to enable localized, pH-responsive chemotherapy for colon cancer. Calcium Carbonate-modified core-shell nanofibers were engineered via coaxial electrospinning, featuring a PCL core loaded with 5-fluorouracil (5-FU) and a hydrophobic TPU shell incorporating 0–20 wt% Calcium Carbonate nanoparticles. The fibers exhibited uniform core-shell morphology (142 ± 50 nm diameter), enhanced mechanical strength (7.8 ± 0.52 MPa vs. 4 ± 0.24 MPa for core-only), increased hydrophobicity (contact angle 82°–88° vs. 75°), and sustained Fickian drug release characterized by minimal burst release (< 10%) and 32% cumulative release over 72 h under simulated colonic conditions. Optimal performance was achieved at 5 wt% Calcium Carbonate, balancing effective drug release (≈ 30% over 72 h.) and biocompatibility (fibroblast viability > 75%), while higher concentrations induced cytotoxicity. This mechanically reinforced nanofiber system demonstrates promising potential as a colorectal stent cover, enabling localized, sustained 5-FU delivery to reduce systemic toxicity and resist mechanical stress in the colon.