Mechanical behavior of a soft hydrogel reinforced with three-dimensional printed microfibre scaffolds

Abstract

Reinforcing hydrogels with micro-fibre scaffolds obtained by a Melt-Electrospinning Writing (MEW) process has demonstrated great promise for developing tissue engineered (TE) constructs with mechanical properties compatible to native tissues. However, the mechanical performance and reinforcement mechanism of the micro-fibre reinforced hydrogels is not yet fully understood. In this study, FE models, implementing material properties measured experimentally, were used to explore the reinforcement mechanism of fibre-hydrogel composites. First, a continuum FE model based on idealized scaffold geometry was used to capture reinforcement effects related to the suppression of lateral gel expansion by the scaffold, while a second micro-FE model based on micro-CT images of the real construct geometry during compaction captured the effects of load transfer through the scaffold interconnections. Results demonstrate that the reinforcement mechanism at higher scaffold volume fractions was dominated by the load carrying-ability of the fibre scaffold interconnections, which was much higher than expected based on testing scaffolds alone because the hydrogel provides resistance against buckling of the scaffold. We propose that the theoretical understanding presented in this work will assist the design of more effective composite constructs with potential applications in a wide range of TE conditions.

Role of Biomaterials and Controlled Architecture on Tendon/Ligament Repair and Regeneration

“…Recently, electro‐hydrodynamic fiber printing techniques, such as melt electrowriting (MEW), can potentially address these limitations by accurate and continuous deposition of microscaled fibers . Typically, this is undertaken by drawing out a single fiber onto a computer‐controlled collector plate that moves in a horizontal plane ( x – y plane) relative to a fixed extruder nozzle (Figure b–d).…”

“…Typically, this is undertaken by drawing out a single fiber onto a computer‐controlled collector plate that moves in a horizontal plane ( x – y plane) relative to a fixed extruder nozzle (Figure b–d). 3D constructs are then achieved by precise and successive fiber‐by‐fiber stacking of straight, sinusoidal or angled‐shaped fibers . Hochleitner et al and Bas et al printed poly(e‐caprolactone‐ co ‐acryloyl carbonate) and PCL scaffolds, respectively, with a crimped structure by manipulating the collector speed and the polymer jet mass flow (Figure b,c) .…”

Multiscale modelling and homogenisation of fibre-reinforced hydrogels for tissue engineering

“…We assume that the PCL fibres are an isotropic linear elastic material, with Young's modulus E f and Poisson's ratio ν f . The published values of Young's modulus for printed PCL fibres vary with the method of printing and radius of the fibre, and so we will assume that E f is between 53 MPa and 363 MPa (for details see [3,28,27,6]), and that the Poisson's ratio ν f is between 0.3 and 0.49 (see [10,11,6]). The dimensional Lamé parameters µ f and λ f in Table 1 are calculated from these values as follows…”

Recent Advances in Enabling Technologies in 3D Printing for Precision Medicine

“…Other methods for the fabrication of heterogenous structures have combined various 3D printing and biofabrication technologies together. For example, recent advances in electrospinning capabilities have enabled greater spatial control over microfiber deposition through a direct melt electrowriting (MEW) process . Direct MEW applies a high voltage electrical field to spatially pattern high‐resolution fibers from polymer melts (Table ).…”

“…These variations may be important when developing patient‐specific in vitro models, or for creating functional personalized implants. Embedded printing techniques overcome challenges in traditional printing methods by utilizing self‐healing materials as support baths (Table ). These fabrication techniques, compatible with a range of bioprinting platforms, also increase material compatibility of extrusion fabrication systems and enhance the resolution and complexity of fabricated constructs .…”