Strontium-Doped Bioglass-Enhanced Extracellular Matrix Mineralization Scaffold for Bone Regeneration

Objectives: This study aims to develop novel small intestinal submucosa (SIS) scaffolds using polydopamine-assisted strontium-doped bioglass (Sr-PDA-BG), followed by in situ mineralization. The physicochemical and biological properties of these scaffolds were investigated for their potential in bone tissue engineering applications.
Methods: Sr-PDA-BG was synthesized by combining strontium chloride and bioactive glass into a polydopamine solution, followed by mixing, drying, and incorporation into a 1% SIS solution. Sr-PDA-BG/SIS scaffolds were fabricated using a freeze-drying method, cross-linked, and subsequently immersed in a mineralization solution containing polyacrylic acid and polyaspartic acid for two weeks, yielding Sr-PDA-BG/mSIS scaffolds. SIS scaffolds without Sr-PDA-BG served as controls.
Morphological analysis was performed using environmental scanning electron microscopy (ESEM), and chemical compositions were assessed by energy-dispersive spectroscopy (EDS). Compressive strength was measured using a universal mechanical testing machine. The proliferation of human bone marrow stem cells (hBMSCs) on the scaffolds was evaluated using cell counting kits. Osteogenic differentiation was assessed via alkaline phosphatase (ALP) activity and alizarin red staining, with quantitative analysis of ALP expression and mineralized nodule formation.
Results: The Sr-PDA-BG/mSIS scaffolds exhibited a highly porous structure with interconnected pores and uniform strontium distribution on the surface. Their compressive strength was significantly greater than that of the SIS control scaffolds. None of the scaffolds displayed cytotoxicity. Sr-PDA-BG/mSIS scaffolds showed significantly enhanced ALP activity and alizarin red staining compared to the control group (P<0.05). Quantitative analysis confirmed increased expression of ALP and mineralized nodules in the Sr-PDA-BG/mSIS scaffolds.
Conclusions: Sr-PDA-BG/mSIS scaffolds demonstrated excellent biocompatibility, superior mechanical strength, and enhanced osteogenic properties, making them promising candidates for bone regeneration applications.

Corresponding author: Yuhua Liu
Yuke Li and Lin Tang contributed equally to this article.