Poloxamer/Poly(ethylene glycol) Self-Healing Hydrogel for High-Precision Freeform Reversible Embedding of Suspended Hydrogel

Abstract

Freeform reversible embedding of suspended hydrogel (FRESH) is an additive manufacturing technique enabling the 3D printing of soft materials with low or no yield stress. The printed material is embedded during the process until its solidification. From the literature, FRESH abilities are self-healing, reusability, suspending, thermal stability, and high-precision printing. This study proposes a new support hydrogel bath formulation for FRESH 3D printing. To do so, a poloxamer micellar thermoreversible hydrogel is tuned through the addition of poly(ethylene glycol) (PEG) to adapt rheological properties. PEG macromolecules interact with poly(ethylene oxide) blocks of poloxamer and favor micelle dehydration, and then decreasing the gelation temperature, the yield stress, and the viscosity. Parameters such as the Oldroyd number and the Rayleigh−Plateau instability, both dependent on yield stress, were studied to determine their impact on the FRESH 3D printing resolution and accuracy. It was found that print accuracy of embedded parts increases with increasing yield stress but then the self-healing property gets limited, leading to crevasse formation. The usefulness of this approach is distinctly demonstrated through a six-axis printing of a highly complex silicone anatomical model. Printing fidelity of 96.0 ± 3.58% (5−40 mm printed parts) is thus achieved using the newly formulated FRESH material, while only 56.0 ± 0.76% fidelity is obtained using the standard formulation. The present study thus showed that complex FRESH 3D printing of soft materials is possible in this tunable hydrogel and that parts can be manufactured on an industrial scale, thanks to the reusability of the support bath.

Extracellular Matrix-Based Biomaterials for Cardiovascular Tissue Engineering

“…Therefore, low viscosity is desirable during extrusion to avoid high shear stress and potential clogging. Upon deposition, a high viscosity rate is needed to maintain shape and high print fidelity to preserve high printing precision such as thermo-responsive gelation of gelatin that retains its shape of printed structure [150]. However, gelatin is not used alone in biofabrication as its reversible sol-gel transition can affect printing temperature and viscosity [151].…”

Soft-tissue-mimicking using silicones for the manufacturing of soft phantoms by fresh 3D printing

“…Different materials were used for creating the thermo-reversible Pluronic V R F-127-based support bath supplied by Sigma Aldrich, USA. The support bath is a mixing of 30Wt.% of Pluronic V R F-127 and 40Wt.% of a plasticizer agent (Colly et al, 2021). Firstly, the 40Wt.% of the plasticizer agent was mixed with deionized water.…”

Fluid Bath-Assisted 3D Printing for Biomedical Applications: From Pre- to Postprinting Stages

“…In addition, the fluid bath offers in situ support, making it unnecessary to create auxiliary supporting structures. As a result, this strategy can be used to fabricate complex geometries from various materials such as elastomers, − hydrogels, ,− composites, − etc. Since its inception, fluid bath-assisted 3D printing has spurred tremendous interest in tissue engineering.…”