Highly porous PLA nanofibers containing borate bioactive glass: Hydroxyapatite formation, cytocompatibility, and osteogenic mineralization

Multifunctional scaffolds that can address both soft and hard tissue requirements remain a key need in regenerative medicine. Herein, highly porous poly(lactic acid) (PLA) nanofibrous mats were produced and incorporated with 45B5 borate bioactive glass (46.1 B₂O₃ - 26.9 CaO - 24.4 Na₂O - 2.6 P₂O₅, mol%) at two nominal dope loadings (2.5 and 5 wt./v %; PLA/2.5_45B5 and PLA/5_45B5) to enhance biological responsiveness. The PLA nanofibers exhibited uniform, bead-free fibers with surface nanoporosity, and with effective glass encapsulation. Glass incorporation induced PLA matrix partial crystallization, while the polymer's characteristic chemical fingerprint remained unchanged, indicating that 45B5 was incorporated predominantly through physical encapsulation. Glass loading increased stiffness but reduced tensile strength and elongation, most notably for PLA/5_45B5, which showed the highest modulus and a brittle fracture profile. In simulated body fluid, only PLA/5_45B5 promoted clear hydroxyapatite formation, indicating a threshold-dependent mineralization response. In vitro assays using fibroblastic (L929) and osteoblast-like (MG63) cells showed overall cytocompatibility across all formulations; fibroblasts maintained metabolic activity over time, whereas MG63 showed a time-dependent metabolic profile with a late decrease that should be interpreted alongside complementary readouts. Importantly, both glass-containing mats enhanced late-stage osteogenic outcomes, increasing calcium deposition and mineralized nodule formation relative to neat PLA. Collectively, these findings position PLA/45B5 nanofibers as composition-dependent scaffolds that maintain compatibility while promoting mineralization-relevant responses for bone repair.