One-step calcium crosslinking of chitosan/alginate/pectin/bioactive glass scaffolds with synergistic osteogenic-angiogenic activity for bone regeneration

Abstract

This study aimed to simplify the fabrication process of bone tissue engineering scaffolds by developing a composite scaffold based on chitosan (CS), sodium alginate (SA), pectin (PEC), and 45S5 bioactive glass (BG) through an integrated one-step CaCl2-mediated crosslinking method. Scaffolds were prepared with varying BG mass fractions (10, 20, 30, and 40 wt%, named CSAP@BG10, CSAP@BG20, CSAP@BG30, and CSAP@BG40) by mixing CS, SA, and PEC solutions (dry ratio 50:40:10) with BG particles. The resulting mixture was then subjected to shaping, Ca2+-mediated crosslinking, freezing, and freeze-drying. Characterization included porosity assessment, infrared spectroscopy (IR), x-ray diffraction (XRD), and simulated body fluid (SBF) evaluation. In vitro studies were performed using bone marrow-derived mesenchymal stem cells (BMSCs). The CSAP@BG20 scaffold exhibited an interconnected porous structure, a favorable swelling ratio, and notable mass retention after degradation. IR and XRD analyses confirmed the successful incorporation of the BG and the retention of its amorphous structural characteristics within the scaffold. A bone-like apatite layer formed on the scaffold after SBF immersion, indicating favorable in vitro bioactivity. In addition, immersion studies showed composition-dependent physicochemical behavior, including mild pH variation and sustained Ca2+ release. BMSCs exhibited enhanced adhesion, proliferation, and osteogenic gene expression in CSAP@BG20 compared with the BG-free control. It also upregulates angiogenic-related factors, demonstrating synergistic osteogenic and angiogenic effects. The integrated one-step CaCl2-mediated fabrication strategy successfully created a scaffold with favorable structure, mechanical properties, and bioactivity. Among the tested formulations, CSAP@BG20 showed the most balanced physicochemical and biological performance. The CSAP@BG20 scaffold shows promise for bone defect repair.