Osteoblast adhesion, proliferation and growth on polyelectrolyte complex–hydroxyapatite nanocomposites

In this work, we have investigated osteoblast adhesion, proliferation and differentiation on nanocomposites of chitosan, polygalacturonic acid (PgA) and hydroxyapatite. These studies were done on both two- and three-dimensional (scaffold) samples. Atomic force microscopy experiments showed nanostructuring of film samples. Scaffolds were prepared by freeze-drying methods. The mechanical response and porosity of the scaffolds were also determined. The compressive elastic modulus and compressive strength were determined to be around 0.9 and 0.023 MPa, respectively, and the porosity of these scaffolds was found to be around 97 per cent. Human osteoblast cells were used to study their adhesion, proliferation and differentiation. Optical images were collected after different intervals of time of seeding cells. This study indicated that chitosan/PgA/hydroxyapatite nanocomposite films and scaffolds promote cellular adhesion, proliferation and differentiation. The formation of bone-like nodules was observed after 7 days of seeding cells. The nodule size continues to increase with time, and after 20 days the size of some nodules was around 735 μm. Scanning electron microscope images of nodules showed the presence of extracellular matrix. The alizarin red S staining technique was used to confirm mineralization of these nodules.