Core–Sheath Nanofibers From a Modified Coaxial Electrospinning for Transdermal Delivery of Finasteride

Traditional blending electrospinning has a series of issues during implementation, and the corresponding monolithic nanofibers can always be updated through the intentional design of core-sheath nanostructures. In this study, a modified coaxial electrospinning approach was employed to refine the electrospinning process by eliminating abnormal phenomena, while simultaneously imparting core-sheath nanostructures and improved transdermal finasteride (FIN) delivery performance. Using an electrospinnable ethylcellulose (EC) solution containing FIN as the core fluid and an unspinnable polyvinylpyrrolidone (PVP)/sodium dodecyl sulfate (SDS) solution as the sheath fluid, medicated core-sheath nanofibers (E3) were fabricated continuously and robustly. The monolithic nanofibers (E2) from a conventional blending electrospinning were prepared as a comparison. FIN existed in an amorphous state within both E2 and E3 nanofibers, attributed to its excellent compatibility with EC. The sustained release profiles of nanofibers E2 and E3 are similar, but the penetration rates of FIN molecules from the nanofibers E2 and E3 always have significant differences from the initial tests at 0.5 h (10.32 ± 4.31% and 12.85 ± 5.14% for nanofibers E2 and E3, respectively) to the final tests at 4.0 h (38.16 ± 5.47% and 51.31 ± 5.19% for nanofibers E2 and E3, respectively). The mechanism underlying the robust preparation enabled by the unspinnable sheath fluid is proposed: it prevents multiple abnormal phenomena inherent to single-fluid blending processes. This protocol offers a versatile strategy to upgrade traditional single-fluid blending electrospinning products, endowing them with an improved functional performance.