Preparation and characterization of PLA/PCL/HA composite scaffolds using indirect 3D printing for bone tissue engineering

Abstract

3D printing-based technologies can fabricate scaffolds offer great precision to control internal architecture and print complicated structures based upon the defect site. However, the materials used in the direct printing are restricted depending on the printing technology used and the indirect one can overcome this limitation. In the present study, indirect 3D printing approach was used to develop bone scaffolds from polylactic acid/ polycaprolactone/ hydroxyapatite (PLA/PCL/HA) composites. Casting of the composite suspensions was done into a dissolvable 3D printed negative mold, in order to achieve simultaneous macro- and micro-porous composites, using freeze drying/particle leaching method. To evaluate morphology, functional groups, and elemental analysis of the scaffolds, scanning electron microscopy (SEM), Fourier transform infrared (FTIR), and energy dispersive spectroscopy (EDS) were respectively used. Scaffolds' porosity was measured with the aid of liquid replacement technique. Also, the mechanical strength of scaffolds was examined by compression test and measuring the compressive modulus Considering the microstructure, porosity and pore size as well as mechanical property, the scaffold composed of PLA/PCL 70/30 w/w and 35% HA was more favorable. The PLA/PCL/HA 70/30-35% scaffold presented a porosity of 77%, an average pore size of 160 μm, and Young's modulus of 1.35 MPa. Cell adhesion, viability and mineral deposits formation for PLA/PCL/HA scaffolds at PLA/PCL ratios of 70/30, 50/50 and 30/70 and the fixed amount of HA (35%) were also studied in vitro by the means of MG63 cells. The cytotoxicity assessment showed that the cells could be viable and proliferate on the scaffolds. The results indicated that composite scaffold with the PLA/PCL weight ratio of70/30 accomplished more favorable properties in terms of biocompatibility, viability, and osteoinduction property.

Keywords: 3D printer; Bone scaffold; Hydroxyapatite; Indirect molding; Polycaprolactone; Polylactic acid.