Fabrication of Robust Poly( <scp>l</scp> -lactic acid) Nanofiber Yarns Loaded with Curcumin@ZIF-8 Nanoparticles for Sustained Drug Release in Biomedical Applications

Electrospun nanofiber yarns loaded with drugs or bioadditives combine nanobionic structures with enhanced bioactivities, showing great promise for advanced biomedical textiles, but are hindered by burst release, short release periods, and poor mechanical properties. This study designed a hierarchical drug encapsulation yarn system. Curcumin (Cur) was first encapsulated into zeolitic imidazolate framework-8 (ZIF-8) to generate Cur@ZIF-8 nanoparticles, which were then loaded into poly(l-lactic acid) (PLLA) nanofibers during a modified electrospinning process and further processed into Cur@ZIF-8 containing PLLA nanofiber yarns by a rolling and thermal stretching process. TEM images demonstrated the successful encapsulation of Cur@ZIF-8 into PLLA nanofibers, and SEM images showed that the addition of Cur@ZIF-8 could dramatically decrease the diameter of the PLLA nanofibers. Mechanical tests indicated that the PLLA nanofiber yarn loading with 2% Cur@ZIF-8 possessed robust mechanical properties with an ultimate stress of 72.1 ± 6.2 MPa. In vitro drug release studies confirmed that the PLLA nanofiber yarn loading with Cur@ZIF-8 exhibited sustained drug release behavior over 15 days with pH-responsive characteristics. The Cur release was quicker in the skin acidic (pH = 5.4) condition compared with the physiological (pH = 7.4) condition. Importantly, the Cur release profiles of PLLA nanofiber yarns loaded with Cur@ZIF-8 conformed to the Korsmeyer–Peppas model during the initial stage (0∼24 h) and the first-order model in the later stage (48∼300 h). Antimicrobial assessment revealed that the Cur@ZIF-8 loaded PLLA nanofiber yarns presented >99% inhibition rates against both Escherichia coli and Staphylococcus aureus, while cytocompatibility evaluation confirmed that the Cur@ZIF-8 loaded PLLA nanofiber yarns significantly promoted the proliferation of human dermal fibroblasts. In all, this study provides a simple method to fabricate Cur@ZIF-8/PLLA nanofiber yarns with controlled drug release, strong mechanical strength, excellent antibacterial/antioxidant performance, and superior biocompatibility, making them promising for use in biomedical textiles.