Melt Electrowriting of a Photo‐Crosslinkable Poly(ε‐caprolactone)‐Based Material into Tubular Constructs with Predefined Architecture and Tunable Mechanical Properties

Abstract

Melt electrowriting (MEW) is an additive manufacturing process that produces highly defined constructs with elements in the micrometer range. A specific configuration of MEW enables printing tubular constructs to create small‐diameter tubular structures. The small pool of processable materials poses a bottleneck for wider application in biomedicine. To alleviate this obstacle, an acrylate‐endcapped urethane‐based polymer (AUP), using a poly(ε‐caprolactone) (PCL) (molar mass: 20 000 g mol−1) (AUP PCL20k) as backbone material, is synthesized and utilized for MEW. Spectroscopic analysis confirms the successful modification of the PCL backbone with photo‐crosslinkable acrylate endgroups. Printing experiments of AUP PCL20k reveal limited printability but the photo‐crosslinking ability is preserved post‐printing. To improve printability and to tune the mechanical properties of printed constructs, the AUP‐material is blended with commercially available PCL (AUP PCL20k:PCL in ratios 80:20, 60:40, 50:50). Print fidelity improves for 60:40 and 50:50 blends. Blending enables modification of the constructs' mechanical properties to approximate the range of blood vessels for transplantation surgeries. The crosslinking‐ability of the material allows pure AUP to be manipulated post‐printing and illustrates significant differences in mechanical properties of 80:20 blends after crosslinking. An in vitro cell compatibility assay using human umbilical vein endothelial cells also demonstrates the material's non‐cytotoxicity.

Volumetric Printing across Melt Electrowritten Scaffolds Fabricates Multi-Material Living Constructs with Tunable Architecture and Mechanics

“…It should be noted that although we focused on PCL as the MEW platform material in this study, the mechanical properties of the MEW fiber reinforcements could also be tuned by utilizing different biomaterial inks. [49][50][51] In addition to tensile testing and burst pressure analyses, the shape stability of these VolMEW cylinders was assessed by evaluating their bending resistance. While a degree of bending flexibility can be desirable to manipulate the VolMEW tubes, unwanted collapse due to the inability of the tubes to sustain their own weight can be detrimental.…”

“…It should be noted that although we focused on PCL as the MEW platform material in this study, the mechanical properties of the MEW fiber reinforcements could also be tuned by utilizing different biomaterial inks. [49–51]…”

Flexible, Suturable, and Leak-free Scaffolds for Vascular Tissue Engineering Using Melt Spinning

“…Early work by Brown et al described the fabrication of tubular scaffolds with control over the winding angle using MEW that resemble the ones in this study, with fibers ranging from 20 to 60 μm, using 50 kDa PCL but a larger-diameter (6 mm) collecting mandrel . Similar work by Pien and colleagues described the fabrication of tubular scaffolds produced by MEW using a photo-cross-linkable acrylate PCL with tunable mechanical properties upon blending with PCL …”

3D Printed Tubular Scaffolds with Massively Tailorable Mechanical Behavior

“…The ability to fabricate tubular MEW scaffolds using a rotating mandrel is of growing interest and has been demonstrated in various works, [ 7–22 ] with proposed tissue engineering applications including vascular, [ 9,14,17,22 ] bone, [ 10,17 ] kidney, [ 12 ] and heart valve. [ 13 ] Tubular scaffolds with aligned fiber meshes [ 16,17 ] and crosshatch (or “diamond”) patterns [ 18 ] are most often reported.…”

“…These 3D fiber networks have been explored for their highly tunable mechanical properties and subsequent influence on cell attachment, proliferation, and tissue regeneration for a range of applications. [1,8,9] The ability to fabricate tubular MEW scaffolds using a rotating mandrel is of growing interest and has been demonstrated in various works, [7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22] with proposed tissue engineering applications including vascular, [9,14,17,22] bone, [10,17] kidney, [12] and heart valve. [13] Tubular scaffolds with aligned fiber meshes [16,17] and crosshatch (or "diamond") patterns [18] are most often reported.…”