Development of electrospun scaffolds for bone regeneration from strontium-doped hydroxyapatite nanorods and thermoplastic polyurethane elastomer

Abstract

Strontium based biomaterials have gained importance in bone tissue regeneration due to their incredible osteoinductivity and differentiation ability. In this study, strontium-doped hydroxyapatite nanorods [SrHAp, Ca<inf>9</inf>Sr(PO<inf>4</inf>)<inf>6</inf>(OH)<inf>2</inf>] were synthesized by the coprecipitation method. Subsequently, electrospun fibrous scaffolds were fabricated from thermoplastic polyurethane elastomer (TPU) dispersed with SrHAp nanorods. The loading of SrHAp nanorods in TPU was varied from 1 wt% to 7 wt% in steps of 2. Morphology of electrospun fibrous scaffolds and the dispersion of nanorods in the TPU matrix were characterised by field emission scanning electron microscopy, and elemental mapping by energy-dispersive x-ray spectroscopy, respectively. The scaffolds exhibited 3D interconnected network structure with well-distributed pores. The SrHAp nanorods were observed to be smoothly dispersed in the polymer matrix in the scaffolds using elemental mapping and transmission electron microscopy. The newly developed scaffolds exhibited adequate mechanical strength combined with good biocompatibility and excellent biomineralization characteristics. Further, MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay of the electrospun scaffolds against gingiva-derived mesenchymal stem cells (gMSCs) revealed excellent survival and growth rate of the cells. In addition, the osteoinductivity study using gMSCs confirms the better osteodifferentiation in the scaffold containing 5 wt% SrHAp compared with its counterparts by showing the expressions of alkaline phosphatase (ALP), osteocalcin (OCN) and RUNX2. Among all the compositions, the one with 3 wt% SrHAp loading demonstrated promising results in terms of fiber uniformity, improved mechanical properties, and enhanced cell viability. Thus, the SrHAp/TPU scaffolds developed in this study have the potential for use in bone tissue regeneration. © 2025 Elsevier Ltd