3D Printable Ethylene-co-vinyl Acetate-Hydroxyapatite Composites for Bone Substitute Applications.

Area of Science:

• Biomaterials Science
• Additive Manufacturing
• Tissue Engineering

Background:

• 3D printing enables complex bioinspired structures but faces challenges with thermoplastic elastomeric filament extrusion.
• Low-modulus polymers like ethylene-vinyl acetate (EVA) are limited for bone tissue scaffold fabrication due to extrusion complexities.

Purpose of the Study:

• To address the limitations of EVA for bone tissue engineering by compounding it with hydroxyapatite (HAP).
• To investigate the effects of HAP incorporation on the extrudability, printability, mechanical properties, and osteoblast interactions of EVA.

Main Methods:

• Compounding EVA with varying HAP concentrations.
• Optimizing pellet-extrusion 3D printing parameters for composite scaffolds.
• Characterizing material properties using Confocal Raman microscopy, SEM, and DMA.
• Evaluating biocompatibility and osteogenic potential through cell culture studies (MG-63 cells) and assays (ALP, Alizarin Red S).

Main Results:

• HAP addition improved EVA extrudability, reducing die swell and warpage, enabling stable 3D printing.
• Composite scaffolds exhibited enhanced mechanical properties, with a 5-fold increase in storage modulus for 40 vol% HAP.
• Scaffolds demonstrated excellent biocompatibility, supporting MG-63 cell viability, proliferation, adhesion, and osteogenic differentiation.
• Statistically significant increases in osteogenic factors and mineralization were observed in HAP-containing scaffolds.

Conclusions:

• EVA-HAP composites, particularly at 40 vol% HAP, offer improved printability and mechanical strength for 3D scaffold fabrication.
• These composites provide a conducive microenvironment for osteoblast activity, promoting bone tissue formation.
• The developed EVA-HAP composite is a promising material for bone tissue engineering applications.