Development of Bone Scaffold using Chitosan Nano-Hydroxyapatite Composite

Bone defects with critical-size fractures require clinical intervention for fracture healing. Commonly used treatments have limitations like donor morbidity, limited donors, and mechanical mismatches. Bone scaffolds are developed to address these limitations and improve bone formation, vascularized ingrowth, and biodegradability as bone remodels. In this study, bone healing scaffolds have been fabricated using a coprecipitated chitosan-nanohydroxyapatite composite. Fourier-transformed infrared spectroscopy, scanning electron microscopy, energy dispersive x-ray analysis, x-ray diffraction spectroscopy and thermogravimetric analysis were used to analyze the extracted chitosan and composite. Cylinder-shaped bone scaffolds were obtained by freeze-drying the composite with gelatin. Scaffold fabrication experiments were conducted by varying the composite: gelatin ratio for better shape retention and mechanical properties. Bone scaffolds were analyzed for porosity, pore size distribution, compressive strength and in-vitro bio-activity. An optimum composition in terms of shape retention and other required properties was obtained by the scaffold fabricated using $70 \%$ composite (Chitosan: nanohydroxyapatite 70:30) and $30 \%$ gelatin. This sample had $85 \%$ porosity exhibiting a compressive strength of 0.2 MPa that mimics the compressive strength of cancellous bone. The bioactivity of the scaffolds was successfully analyzed by conducting an in vitro biomineralization test for the composite and an in vitro biodegradation test for the scaffold.