Fiber-Reinforced Printing (FiRePrint) - a novel method for the production of load-oriented 3D scaffolds in biohybrid implants.

Abstract

Personalized medicine focuses on the needs of individual patients, with biohybrid implants being one key area. Various textile or additively manufactured structures have been established to allow the design of load-orientated scaffolds, but they all have specific limitations. The aim of this study is to develop a new manufacturing process (FiRePrint) for the fabrication of load-oriented 3D scaffolds for biohybrid implants. The FiRePrint process is intended to combine the specific advantages of textiles (high tensile strength and flexibility with low material thickness) and 3D printing (feasibility of complex 3D structures).
Material & Methods: A fused deposition modeling printer was modified to facilitate continuous textile fiber feeding to the print head. In this way, we produced composite structures consisting of a thermoplastic polyurethane matrix and continuous fiber reinforcement using a polyethylene terephthalate multi-filament yarn. We also examined the mechanical properties, microscopic morphology and cell biology.
Results: We were able to print thin-walled scaffold structures (150 µm) with the flexibility of thermoplastic polyurethane and the Young's modulus and tensile strength of textile structures. Furthermore, we were able to print single tracks, open-porous and closed surfaces and complex load-oriented structures (2D and 3D). The scaffold structures showed no cytotoxicity and supported cell viability, adhesion, proliferation and confluence. 
Conclusion: By combining the design flexibility of 3D printing with the mechanical properties of continuous textile fibers, we were able to fabricate load-oriented scaffolds for biohybrid implants without the current limitations of classic fabrication strategies. Our approach provides a novel manufacturing technology for biomedical scaffold structures with enhanced biomimetic mechanical properties.