Nonwoven nanofibrous PLA/SiO₂-gelatin/hydroxyapatite hybrid scaffolds by two-nozzle electrospinning: bone tissue engineering applications.

This study presents the fabrication and optimization of poly(lactic acid)/gelatin (PLA/Gel) composite nanofibrous scaffolds simultaneously reinforced with hydroxyapatite (HA) and silica (SiO₂) nanoparticles using a dual-nozzle electrospinning approach. Separate PLA/SiO₂ and Gel/HA solutions were electrospun simultaneously, but each from one distinct syringe to enable independent control of processing parameters. Compositional and processing parameters were systematically optimized using the Taguchi design method, a novel approach for this type of hybrid scaffold. Morphological analysis showed that fiber diameter could be tuned by adjusting formulation parameters, with average diameters ranging from approximately ~200 nm to ~1000 nm under stable electrospinning conditions. Uniform, bead-free nanofibers were obtained at balanced compositions, whereas higher nanoparticle loadings led to greater diameter variability and bead formation. Surface wettability was tunable, with contact angles ranging from 130° to 28°, depending on composition. Thermal analyses revealed that both nanoparticle content and polymer blend ratio significantly influenced degradation and crystallization behavior. The optimized scaffold, consisting of a 50/50 Gel/PLA with 2 wt% HA and 2.5 wt% SiO₂, exhibited uniform, bead-free morphology, favorable hydrophilicity, and mechanical properties suitable for bone tissue engineering (tensile strength 3.5 MPa; Young's modulus 180 MPa). In vitro evaluations demonstrated enhanced cell viability, proliferation, mineralization, and osteogenic differentiation, particularly in HA/SiO₂-reinforced structures. Overall, these findings underscore the effectiveness of dual-nozzle electrospinning combined with Taguchi optimization for tailoring PLA/Gel nanofibers structure and performance in advanced bone tissue engineering applications.