Solvent casting-salt leaching synthesis, characterization, and biocompatibility of three-dimensional porous chitosan/nano-hydroxyapatite scaffolds for bone tissue engineering

In this work, we developed three-dimensional (3D) porous chitosan/nano-hydroxyapatite scaffolds (CS/HAp) for bone tissue engineering (BTE) using a solvent casting-salt leaching technique. The physicochemical, morphological, and porous analyses of the scaffolds were performed using X-ray diffraction, Fourier-transform infrared spectroscopy, scanning electron microscopy (SEM), and the liquid displacement method. Results indicated that nano-HAp particles were successfully integrated into the CS matrix to produce 3D CS/HAp scaffolds. These scaffolds exhibited a highly porous structure with a thickness of 2 mm and average pore sizes from 285 to 345 µm and porosity (76.76–86.52%), which are beneficial for cell growth. Additionally, the scaffolds showed increased Young’s modulus (10.9–14.8 MPa) and tensile strength (2.4–2.6 MPa) compared to pure CS scaffolds that are well-compatible with trabecular bone. The degradation rate of the CS/HAp scaffolds was slower than that of the CS scaffolds alone. Notably, a bone-like apatite layer was formed on the CS/HAp scaffold’s surfaces after 15 days of immersion in simulated body fluids (SBF). In contrast, no such mineral layer was observed on the CS scaffolds. The protein adsorption on the surfaces of the CS/HAp scaffolds was significantly high, with 840.96 µg of proteins adsorbed after 24 h in 10% of fetal bovine serum (FBS) in a minimum essential medium. In vitro tests with bone marrow-derived mesenchymal stem cells (BMSCs), including live/dead staining, MTT assay, and SEM, confirmed that all scaffolds exhibit excellent biocompatibility, providing a suitable substrate for cell proliferation and adhesion. Furthermore, the CS/HAp scaffolds demonstrated a high removal efficiency of E. coli, reaching up to 84.92% in 180 min. Our results revealed that the CS/HAp scaffolds are potential biomaterials for BTE applications.