Optimizing Hydroxyapatite Loading in Electrospinning Polyvinyl Pyrrolidone Fibers Toward Biocompatible Scaffolds for Critical-Sized Bone Defects

Critical-sized bone defects exceed the body's natural healing capacity and often require scaffold materials to support bone regeneration. Polyvinylpyrrolidone (PVP) is widely used in biomedical applications due to its biocompatibility; however, its osteoconductive performance and mechanical robustness are limited when used alone. To address these limitations, hydroxyapatite (HA) was incorporated into PVP fibers and fabricated into electrospinning scaffolds. PVP/HA composites were prepared at PVP:HA weight ratios of 100:0 (A), 80:20 (B), 60:40 (C), and 40:60 (D), and characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), porosity testing, and in vitro degradation in simulated body fluid (SBF) over 21 days. Among all compositions, the 40:60 scaffold (Sample D) showed the most favorable structural features, exhibiting the smallest average fiber diameter (326 ± 95 nm), the highest porosity (86.03%), and an increased crystallinity. In SBF, Sample D displayed controlled degradation, with weight loss increasing from 20.55% (day 7) to 61.06% (day 21). Overall, increasing HA loading improved scaffold microstructure and degradation behavior, suggesting that the 40:60 PVP/HA composition offers an optimal balance for electrospinning scaffold design toward bone tissue engineering applications.