Facile manufacturing of fused-deposition modeled composite scaffolds for tissue engineering-an embedding model with plasticity for incorporation of additives.

The fused-deposition modeling (FDM) process is carried out at an elevated temperature, preventing the addition of biological factors, drugs, bioactive compounds, etc, during fabrication. To overcome this disadvantage, a 3D interlinked porous polylactic acid (PLA) scaffold was fabricated by FDM, followed by the embedding of a polycaprolactone (PCL) scaffold into the pores of the PLA at room temperature, yielding a PLA-PCL scaffold. In addition, PLA-PCL scaffolds with nanohydroxyapatite (PLA-PCL-nHAP) and multiwalled carbon nanotubes (PLA-PCL-MWCNT) were also fabricated. Here, the FDM-fabricated PLA scaffold functions as the structural component, whereas the embedded PCL scaffold acts as the functional component, which provides a the ability to functionalize the scaffolds with the desired chemical or biological materials. The embedding process is straightforward, cost effective, and does not require sophistication. A mechanical characterization of the scaffolds suggests that the Young's modulus of the PLA-PCL scaffold (16.02 MPa) was higher than that of the FDM-fabricated PLA (9.98 MPa) scaffold, by virtue of embedded PCL matrix. In addition, finite element analysis showed that the von Mises stress on a mandible with scaffolds was 4.04 MPa, whereas for a mandible with a defect, it was 6.7 MPa, confirming the stress distribution efficiency and mechanical stability of these scaffolds. Furthermore, field emission-scanning electron microscope analysis implied the presence of interlinked porous structures with pore diameters of 50 µm to 300 µm. X-ray diffraction results revealed an increased crystallinity (%) in the embedded models (PLA-PCL, PLA-PCL-nHAP and PLA-PCL-MWCNT), compared to a PLA printed scaffold. Additionally, Raman analysis revealed that the embedding process did not cause chemical alterations in the polymeric chains. In vitro analysis with human osteoblasts demonstrated the osteoconductive nature of the scaffold, which supported mineralization. In brief, the advantage of our model is that it helps to overcome the difficulties of manufacturing a filament with the desired additives for FDM, and offers the ability to incorporate the desired concentrations of heat-labile bioactive molecules during the embedding process at ambient temperatures.