Design of Thermoplastic 3D-Printed Scaffolds for Bone Tissue Engineering: Influence of Parameters of “Hidden” Importance in the Physical Properties of Scaffolds

Abstract

Additive manufacturing (AM) techniques are becoming the approaches of choice for the construction of scaffolds in tissue engineering. However, the development of 3D printing in this field brings unique challenges, which must be accounted for in the design of experiments. The common printing process parameters must be considered as important factors in the design and quality of final 3D-printed products. In this work, we study the influence of some parameters in the design and fabrication of PCL scaffolds, such as the number and orientation of layers, but also others of “hidden” importance, such as the cooling down rate while printing, or the position of the starting point in each layer. These factors can have an important impact oin the final porosity and mechanical performance of the scaffolds. A pure polycaprolactone filament was used. Three different configurations were selected for the design of the internal structure of the scaffolds: a solid one with alternate layers (solid) (0°, 90°), a porous one with 30% infill and alternate layers (ALT) (0°, 90°) and a non-alternated configuration consisting in printing three piled layers before changing the orientation (n-ALT) (0°, 0°, 0°, 90°, 90°, 90°). The nozzle temperature was set to 172 °C for printing and the build plate to 40 °C. Strand diameters of 361 ± 26 µm for room temperature cooling down and of 290 ± 30 µm for forced cooling down, were obtained. A compression elastic modulus of 2.12 ± 0.31 MPa for n-ALT and 8.58 ± 0.14 MPa for ALT scaffolds were obtained. The cooling down rate has been observed as an important parameter for the final characteristics of the scaffold.

Assessment of a PCL-3D Printing-Dental Pulp Stem Cells Triplet for Bone Engineering: An In Vitro Study

“…The ability to facilitate cell attachment and induce cell proliferation is one of the frequently mentioned concerns related with the use of additive manufacturing techniques [ 10 ]. Though, pore morphology obtained with 3D printing should facilitate cell proliferation [ 47 ], complementary techniques are proposed to overcome this problem and generate additional topography features than increment cell adhesion and guides for cell proliferation [ 48 ].…”

“…Though, pore morphology obtained with 3D printing should facilitate cell proliferation [ 47 ], complementary techniques are proposed to overcome this problem and generate additional topography features than increment cell adhesion and guides for cell proliferation [ 48 ]. However, careful control of the printing parameters allows the manipulation of these features in 3D printing as shown in a previous work [ 10 ]. In the current manuscript we investigate the potential for DPSC attachment and proliferation of a 3D printed scaffold without introducing further topography features.…”

“…The polycaprolactone (PCL) used in this project was directly provided as a 1.75 ± 0.005 mm filament for standard 3D printers ( (accessed on 7 March 2021), M w : 84,500 ± 1000, 100% pure, Haarlem, The Netherlands). Polymer characterization is described somewhere else [ 10 ].…”

“…PCL favorable properties for bone engineering include long-term biodegradability, ease of processing due to the low melting temperature (58–60 °C), suitable rheological, viscoelastic properties and thermal stability. Because of its history in drug delivery devices, PCL has also a shorter regulatory path to market than many other polymer systems through the Food and Drug Administration (FDA) and the European Medicines Agency (EMA) [ 10 ]…”

“…The production of scaffold suitable for tissue engineering has been approached using different techniques. Among them, supercritical drying [ 11 ] and 3D printing [ 10 ] are the most innovative. Additive manufacturing (AM) techniques are becoming the techniques of choice for the development of scaffolds as implants and in tissue engineering.…”