Magnetic Electrospun Polycaprolactone (PCL) Fibers Modified with Oleic Acid-Coated Iron Oxide Nanoparticles

Magnetic polycaprolactone (PCL) fibers containing oleic acid-coated iron oxide nanoparticles (IONPs/OA) were produced by electrospinning. First, a systematic study was carried out to determine the optimal processing parameters, establishing a 20% (w/v) PCL concentration, an applied voltage of 20 kV, a needle-to-collector distance of 22 cm, and a flow rate of 2 mL/h as the most suitable parameters. Homogeneous neat PCL fibers with an average diameter of 543 ± 88 nm were obtained under these conditions. Subsequently, different IONPs/OA concentrations (5, 10, and 20 wt %) were incorporated, leading to a progressive increase in fiber diameter, with a maximum of 961 ± 201 nm for the 20 wt % formulation. Magnetic measurements confirmed superparamagnetic behavior at room temperature for all composite fiber samples, with a maximum saturation magnetization (M _s) of 6.1 ± 0.1 emu/g for the 20 wt % formulation. Thermogravimetric analysis revealed that the incorporation of IONPs/OA into the fibers decreased the degradation temperature by approximately 63 °C compared to neat PCL. Finally, water contact angle (WCA) measurements revealed a progressive increase in fiber hydrophobicity, reaching a maximum WCA of 135°. These results indicate that the produced fibers exhibited promising morphological, compositional, thermal and magnetic properties for potential future biomedical applications, such as drug delivery and magnetic hyperthermia.