| Processing and composition can signifcantly affect the mechanobiology, biodegradability, and cellular behavior
of polymer-based bone scaffolds to replace damaged bone tissue. In this research, hydroxyapatite (HA), zincdoped HA (ZnHA), and ZnHA-graphene (ZnHA-rGO) nanoparticles are composed in a polycaprolactone (PCL)
matrix. After compositing PCL with nanoparticles, 3D bone scaffolds were built by a custom-built 3D printing
system. The characterization of nanoparticles was extensively investigated by TEM, EDX-MAP, XRD, and ATRFTIR. Simultaneously, 3D-printed scaffolds with different compositions were studied in terms of structure,
morphology, thermogravimetry, biodegradability, and mechanical behaviors. The FE-SEM images of the scaffolds showed a highly regular structure and good printability of the developed material system. Moreover, the
stiffness modulus of the samples increased due to the presence of the nanoparticles, especially in the ZnHA-rGO
nanocomposite. In vitro cell assessment of 3D bone scaffolds was investigated by cell viability tests, cell
attachment, and alizarin red staining via mesenchymal stem cells (MSCs). For differentiation capacity of the
developed scaffolds, stem cell osteogenesis differentiation was studied by RT-PCR to analyze the ALP, RUNX2,
BMP2, TGFβ, and OCN genes. The cellular assessments revealed an increase in PCL scaffold’s cell osteogenesis
due to the HA nanoparticles in the scaffold matrix. Zinc doping in the HA nanoparticles and rGO addition
signifcantly increased the osteogenesis of MSCs. In particular, the nanocomposite of ZnHA-rGO in PCL scaffold
matrix signifcantly improved the osteogenic differentiation and, thus, it is a viable option for effective regeneration of damaged bone tissue. |