Supercritical CO₂ assisted process for the production of high‐purity and sterile nano‐hydroxyapatite/chitosan hybrid scaffolds

Abstract

Hybrid scaffolds composed of hydroxyapatite (HAp), in particular in its nanometric form (n-HAp), and chitosan (CS) are promising materials for non-load-bearing bone graft applications. The main constraints of their production concern the successful implementation of the final purification/neutralization and sterilization steps. Often, the used purification strategies can compromise scaffold structural features, and conventional sterilization techniques can result in material's thermal degradation and/or contamination with toxic residues. In this context, this work presents a process to produce n-HAp/CS scaffolds mimicking bone composition and structure, where an innovative single step based on supercritical CO extraction was used for both purification and sterilization. A removal of 80% of the residual acetic acid was obtained (T = 75°C, p = 8.0 MPa, 2 extraction cycles of 2 h) giving rise to scaffolds exhibiting adequate interconnected porous structure, fast swelling and storage modulus compatible with non-load-bearing applications. Moreover, the obtained scaffolds showed cytocompatibility and osteoconductivity without further need of disinfection/sterilization procedures. Among the main advantages, the proposed process comprises only three steps (n-HAp/CS dispersion preparation; freeze-drying; and supercritical CO extraction), and the supercritical CO extraction show clear advantages over currently used procedures based on neutralization steps. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 965-975, 2018.

Combination of Human Amniotic Fluid Derived-Mesenchymal Stem Cells and Nano-hydroxyapatite Scaffold Enhances Bone Regeneration

“…Chitosan-nanocomposite scaffolds, the biomaterials that were utilised in the current research, are deemed osteoconductive materials to both cell adhering and tissue ingrowth, and it couples biomaterial resorption with bone formation [40], [41]. However, The SEM images of hAF-MSCs seeded on the 3D scaffold, 30% Nano-hydroxyapatite chitosan, have demonstrated a higher healing potential compared to the control, non-seeded scaffold, 30% Nano-hydroxyapatite chitosan at 2 and 4 weeks post-transplantation.…”

Electrospun Porous PDLLA Fiber Membrane Coated with nHA

“…Once the autologous cells take hold and grow on the scaffold, the tissue engineering scaffold can be transplanted into the patient without fear the reaction temperature was controlled at 55 • C. The reaction mixture was then aged for 24 h at room temperature. Finally, the wet nHA was separated by high speed centrifuge at 5000 rpm and washed several times with distilled water and absolute ethyl alcohol [11,12,24].…”

Micropatterned Silica Films with Nanohydroxyapatite for Y-TZP Implants

“…Characteristics such as release of ions (calcium and phosphate), chemical similarity to bone, and nanometric dimensions also help in biological behavior. Therefore, nano-HA addition is an efficient way to increase cell proliferation, stimulate cell differentiation, and improve bone formation (Kilpadi et al 2001; Laranjeira et al 2010; Fu et al 2017; Nievethitha et al 2017; Santos et al 2017; Zhang et al 2017; Ruphuy et al 2018).…”