Fabrication and Characterization of Electrospun Sr/Zn-Doped Nano-Hydroxyapatite-Collagen-PLGA Nanofibrous Scaffolds for Bone Tissue Engineering.

Introduction: Bone tissue engineering (BTE) presents a promising strategy for addressing critical-size bone defects that surpass the intrinsic regenerative capacity of bone tissue. This study presents the fabrication and characterization of biomimetic electrospun scaffolds composed of strontium/zinc co-doped nano-hydroxyapatite (Sr/Zn-nHAp), collagen, and poly(lactic-co-glycolic acid) (PLGA) polymer for BTE applications. Methods: Electrospinning was employed to fabricate the scaffolds, which were subsequently analyzed for their structural, mechanical, bioactivity, biodegradation, and ion release characteristics. Results and Discussion: X-ray diffraction (XRD) confirmed the successful incorporation of Sr/Zn into the nHAp lattice, reducing crystallinity and enhancing bioactivity. Fourier-transform infrared spectroscopy (FTIR) revealed characteristic peaks corresponding to nHAp, collagen, and PLGA, with clear evidence of chemical interactions between the constituents. Mechanical testing using nanoindentation demonstrated superior mechanical performance in the 4% Sr/Zn-doped scaffolds, with a Young's modulus of 9.91 ± 1.7 GPa and hardness of 0.30 ± 0.08 GPa, values comparable to those of cancellous bone. Scanning electron microscopy (SEM) showed a uniform nanofibrous structure with interconnected pores (2.9 ± 0.076 µm). In vitro assay confirmed substantial bioactivity, with apatite formation after 14 days of immersion in simulated body fluid (SBF). The ion release study indicated a sustained release of Ca2+, Sr2+, and Zn2+, which can promote osteogenesis and antibacterial activity. Biodegradation studies demonstrated a controlled degradation profile with minimal pH fluctuations. Conclusion: Collectively, these findings suggest that the 4% Sr/Zn-nHAp-collagen-PLGA electrospun scaffolds possess favorable structural, mechanical, and biological properties, making them promising candidates for orthopedic applications.