Electrospun PCL/Zein Fibers with Naringin or Naringenin for Potential Bone Repair Applications: Physicochemical and Preliminary Biological Evaluation

Electrospun fibers can reproduce the architecture of natural tissues while enabling the controlled release of bioactive compounds; therefore, this study evaluated whether the PCL/zein ratio and flavonoid identity govern the properties of fibers loaded with naringin (NI) or naringenin (NE). PCL and PCL/zein (90:10 and 80:20) fibers containing 5 wt.% NI or NE were produced by electrospinning and characterized by computational analysis, morphology, thermal and mechanical testing, water uptake, degradation, flavonoid release, antioxidant and antibacterial assays, and MG-63 viability and ALP activity. All formulations yielded homogeneous fibers. Increasing the zein content reduced fiber diameter to 0.53 ± 0.20 µm and increased water uptake to ~460%, while fibers containing 20% zein and NE exhibited the highest Young’s modulus (15.22 ± 1.42 MPa). Zein modulated NI and NE release in a flavonoid-dependent manner, with increasing zein promoting greater retention of NE over 72 h. PZ20NE showed the highest antioxidant activity (49.6%) and near-complete inhibition of S. aureus (~99.8%), and approximately 85% inhibition of E. coli. All formulations maintained high MG-63 cell viability, while fibers containing 20% zein and NI produced the strongest ALP response. Overall, scaffold performance depended on polymer ratio and flavonoid structure, supporting their potential as multifunctional materials for future bone tissue repair applications.