Dados do Trabalho

Título/Title/Titulo

Optimization of 3D printing parameters for obtaining polyesterurethane scaffolds for tissue engineering

Introdução/Introduction/Introdución

In recent years 3D printing technologies have gained the attention of researchers specialized in tissue engineering (TE). The mean role of 3D printing in TE is to provide a microenvironment that mimics the intricate properties of the native extracellular matrix (ECM), favoring the infiltration of seeded cells and conducting to the generation of a specific tissue. Moreover, 3D printing technologies must be able to yield quality scaffolds with controlled pore size, interconnectivity, adequate mechanical strength, biodegradability, and the ability to support cellular growth.
Fused deposition modelling (FDM) is one of the most common 3D printing methods to fabricate structures with controlled internal and external geometry layer-by-layer using computer-aided design (CAD).

Objetivos - Metodologia - Resultados - Discussão dos Resultados/Objectives - Methodology - Results - Discussion of Results/Objetivos - Metodología - Resultados - Discusión de los resultados

OBJECTIVES
Fabricate bioresorbable scaffolds by FDM using filaments obtained by extrusion of segmented polyesterurethanes (SPU).

METHODOLOGY
Fabrication of SPU filaments
Bioresorbable SPU based on poly(ε-caprolactone)diol (PCL diol), 1,6-hexamethylene diisocyanate (HDI) and 1,4-butanediol (BDO) (50% w/w hard segment) was synthetized by two-step polymerization using N,N-dimethylacetamide as solvent and dibutyltin dilaurate as catalyst. The product was extruded by a twin-screw microextruder (Thermo Fisher Scientific Process 11) to prepare polymer filaments.
FDM printing
The effects of different FDM processing parameters such as nozzle size, printing speed, layer thickness, printing orientation, nozzle and build plate temperature on the scaffolds fabrication were evaluated. In order to optimize the pore size, different infill densities were studied.
Morphology analysis
The scaffolds were examined by optical microscopy and scanning electron microscopy (SEM).

RESULTS AND DISCUSSION
After setting proper conditions, SPU filament was easily obtained by extrusion of the powdered elastomer without additives. The SPU filament was evaluated for the fabrication of 3D printed scaffolds by FDM. The control of pore size is essential in the development of 3D scaffolds for tissue engineering. Particularly, it was reported that scaffolds with a mean pore size of 325 micrometer are optimal for bone tissue engineering. Thus, FDM parameters were explored to control pore size and porosity of the material. Depending on the infill density employed, 3D printed SPU scaffolds with controlled pore sizes between 120 micrometer and 1 millimeter were obtained. Moreover, the defect-free scaffolds were obtained. In order to evaluate their potential for bone tissue engineering, nanocomposites with bioactive nanoparticles are being incorporated and mechanical properties as well as in vitro assays will be studied.

Considerações Finais/Final considerations/Consideraciones finales

CONCLUSIONS
3D printed scaffolds based on SPU were fabricated successfully. The printed structures showed dimensional stability and high reproducibility. The desired geometry, pore size and porosity could be achieved by setting FDM parameters.

FINAL CONSIDERATIONS
Considering the rapid growth of the 3D printing techniques, materials engineered to be compatible with these processes are likely to become a field of increased importance in the upcoming years. This is expected to be driven by increased industrial adoption of 3D printing processes and an increased demand for materials that meet their needs and expectations.

Palavras-chave/Key words/Palabras clave

Polyesterurethane - Filaments - Extrusion - Fused deposition modelling - Scaffolds - Tissue Engineering