Bone Tissue Engineering: Hybrid 3D-Printed Scaffold With Enhanced Mechanical Properties

Objectives: Polymeric scaffolds composed of polycaprolactone (PCL) were fabricated through 3D printing, with their surfaces being chemically functionalized with either NaOH or 1,6-hexanediamine. The scaffolds were then coated with gelatin foam to increase nutrient transportation while also maintaining superior mechanical properties, biocompatibility, and cell adhesion.
Methods: The scaffolds were 3D printed with optimized parameters. Once printed, the PCL scaffolds were immersed in either 50%(w/w) NaOH or 10%(w/w) isopropanol solution of 1,6-hexanediamine for 0.5, 1, and 3 hours at 50°C. The treated scaffolds were then immersed in 2.5wt% of glutaraldehyde/PBS solution for 24h at room temperature. Gelatin foam, created by mixing 10wt% of porcine gelatin at 1500 rpm for 15 minutes, was thoroughly coated on the scaffolds at room temperature for 1 hour. The morphology and mechanical properties of fabricated scaffolds were characterized with 3D-laser microscopy and an electromechanical precision universal tester, respectively. Dental pulp stem cells (DPSC) were seeded and cultured on each scaffold. Cell adhesion was observed with SEM imaging after fixing in Karnovsky’s solution for 2 hours.
Results: The mechanical properties of scaffolds with no modification, modification via NaOH, and chemical modification (1,6-hexanediamine) were compared. Scaffolds with chemical modification proved to have the greatest values for both max force (11.44±3.07 N) and stress (37.08±4.87 kPa), resulting in these scaffolds being coated with gelatin foam and further analyzed. Additionally, the chemically modified scaffolds displayed uniform porosity. Reinforced gelatin foam coating further enhanced the mechanical properties of fabricated scaffolds. DPSC adhesion was evaluated with SEM images and showed a greater affinity for attachment on the gelatin foam coated scaffolds.

Conclusions: When compared to bare PCL scaffolds, the chemically modified gelatin foam coated PCL scaffold displayed significantly stronger mechanical properties and better cell adhesion, demonstrating their potential for use in bone tissue engineering.