Preparation of magnetic scaffolds via supercritical carbon dioxide foaming process using iron oxide nanoparticles coated with CO2-philic materials as nucleating agents

The iron oxide nanoparticles (IONs), coated with different materials, are synthesized and utilized as nucleating agents to prepare magnetic multi-modal porous scaffolds of poly (lactic-co-glycolic acid)/IONs using the supercritical carbon dioxide (ScCO₂) foaming process. The effects of the modification materials, including citric acid, polycaprolactone, and polyvinyl acetate, on the foaming process and properties of the magnetic scaffolds are systematically investigated. The results indicate that the solubility and diffusion ability of CO₂ in the foaming materials played a vital role in the foaming process. The use of CO₂-philic materials and high pressure proves beneficial in generating micropores. The scaffolds with multi-modal porous structures can be obtained at relatively low pressure for the ScCO₂ foaming systems evaluated in this study. Furthermore, the prepared scaffolds exhibit high porosity and a good compressive modulus (higher than 0.4 MPa), satisfying the requirements of tissue engineering for soft tissue scaffolds.