Robust hierarchical porous Polycaprolactone/nano-Hydroxyapatite/ Polyethylene glycol scaffolds with boosted in vitro osteogenic ability

The reconstruction of bone defects is an important challenge in tissue engineering. Nano-hydroxyapatite (nHA) and polycaprolactone (PCL) composite scaffolds play an important role in bone tissue engineering due to their excellent biological activity, mechanical properties, and osteogenic properties. However, multi-dimensional voids are required during cell infiltration and growth, and the HA and PCL composite scaffold cannot meet the conditions well. In this work, polyethylene glycol (PEG) with hydrophilic and rapid degradation characteristics was introduced into the PCL/nHA system to form porous scaffold. Meanwhile, the physicochemical properties, biological safety, and biological activity of the scaffold were evaluated. It was found that the composite scaffolds with the addition of PEG were safe and non-toxic, which not only improved the hydrophilicity, porosity and degradation rate of the scaffolds, but also formed 20 nm to 4 mu m microscopic pores after hydrolysis, together with the large pores of 100-200 mu m prepared by Fused Deposition Modelling (FDM), which jointly endowed the scaffolds with a rich multilevel pore structure. Moreover, this micropore can be adjusted by modulating the content of the added PEG, which is beneficial to cell adhesion, enhance the in vitro osteogenic ability, and expect to become future bone tissue engineering scaffolds.