Optimization of composite bone scaffolds prepared by a new modified foam replica technique

Abstract

This study aimed to demonstrate the application of the recently developed modified polyurethane (PU) foam replica technique in the fabrication of the hydroxyapatite (HA)/alumina (Al2O3) composite bone scaffolds with different volume fraction quantities of the alumina. Furthermore, the optimum values of porosity and volume fraction of the alumina were obtained in order to achieve an ideal scaffold suitable for repairing the damaged cancellous bone tissues existent in different anatomical locations of the body. Introducing a specific ageing process, samples with excellent properties suitable for bone fracture healing were produced in this study. 20 different groups of the scaffolds, each one comprising 20 samples, which included specimens with different porosities and compositions, were synthesized and characterized regarding morphology, composition, porosity, and mechanical properties. The field emission scanning electron microscopy (FESEM) and nano-computed tomography (nano-CT) images of the samples demonstrated that the scaffolds with high value of porosity and interconnectivity between the pores were achieved via the proposed scheme. According to the findings, although the overall trend of the variation in the viscosity of different HA/Al2O3 slurry compositions during the ageing process were the same, their ageing time was different. Besides, depending on the volume fraction of the alumina and the porosity of the foams used in synthesis of the samples, the values of the porosity and the compressive strength of the scaffolds were varied from 55.72% to 84.76% and 1.67–7.13 MPa, respectively, which are good for bone tissue engineering applications. Moreover, the results obtained from the optimization process revealed that the scaffolds with the respective values of the porosity and the alumina volume fraction of 84.76% and 0% for lumbar spine, 62.83% and 6.57% for proximal tibia, 56.16% and 9.33% for proximal femoral, and 55.72% and 9.8% for femur are the best choices for healing the corresponding injured spongy bone tissues.