Influence of shear thinning and material flow on robotic dispensing of poly(ethylene glycol) diacrylate/poloxamer 407 hydrogels

Kraut, Gabriele; Yenchesky, Laura; Prieto, Fermin; Tovar, Günter E. M.; Southan, Alexander

doi:10.1002/app.45083

Cited by 24 publications

(26 citation statements)

References 31 publications

(51 reference statements)

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“…22 A bioink's viscosity, shear-thinning, and thixotropic behaviors can be measured through rheology, and several mathematical models relating these measurements to extrudability and cell damage have been well-established. 26,44,45 As such, rheological characterizations can be successfully used as indirect measures of extrudability. Most notably, frequency sweeps have been used to measure the viscosity of bioinks across different shear rates.…”

Section: Extrudabilitymentioning

confidence: 99%

“…Meanwhile, the flow index relates to the shear-thinning abilities of the bioink, with a flow index of one indicating Newtonian behavior and values closer to zero indicating a higher degree of shear-thinning and therefore extrudability. 26,[46][47][48][49][50][51] Extrudability has been characterized in several other manners by researchers. Utilizing a piston-driven bioprinting system, Chung et al held strain rate constant and measured the extrusion force.…”

Section: Extrudabilitymentioning

confidence: 99%

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Assessment methodologies for extrusion-based bioink printability

Gillispie¹,

et al. 2020

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Extrusion-based bioprinting is one of the leading manufacturing techniques for tissue engineering and regenerative medicine. Its primary limitation is the lack of materials, known as bioinks, which are suitable for the bioprinting process. The degree to which a bioink is suitable for bioprinting has been described as its "printability." However, a lack of clarity surrounding the methodologies used to evaluate a bioink's printability, as well as the usage of the term itself, have hindered the field. This article presents a review of measures used to assess the printability of extrusion-based bioinks in an attempt to assist researchers during the bioink development process. Many different aspects of printability exist and many different measurements have been proposed as a consequence. Researchers often do not evaluate a new bioink's printability at all, while others simply do so qualitatively. Several quantitative measures have been presented for the extrudability, shape fidelity, and printing accuracy of bioinks. Different measures have been developed even within these aspects, each testing the bioink in a slightly different way. Additionally, other relevant measures which had little or no examples of quantifiable methods are also to be considered. Looking forward, further work is needed to improve upon current assessment methodologies, to move towards a more comprehensive view of printability, and to standardize these printability measurements between researchers. Better assessment techniques will naturally lead to a better understanding of the underlying mechanisms which affect printability and better comparisons between bioinks. This in turn will help improve upon the bioink development process and the bioinks available for use in bioprinting.

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Section: Extrudabilitymentioning

confidence: 99%

Section: Extrudabilitymentioning

confidence: 99%

Assessment methodologies for extrusion-based bioink printability

Gillispie¹,

et al. 2020

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“…However, these additional bioink components can alter the mechanical and physiological properties of the resulting printed structures, which can negatively affect the cell growth and differentiation within the materials. Therefore, sacrificial materials, such as alginate [ 32 ] and poloxamer 407 [ 33 ] have been used to improve printability of hydrogel‐based bioinks. In this study, cold water fish gelatin was used as a sacrificial material to enhance the printability of the designed bioink ( Figure A).…”

Section: Figurementioning

confidence: 99%

Human‐Recombinant‐Elastin‐Based Bioinks for 3D Bioprinting of Vascularized Soft Tissues

Lee

Sani

Spencer³

et al. 2020

Advanced Materials

117

101

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Bioprinting has emerged as an advanced method for fabricating complex 3D tissues. Despite the tremendous potential of 3D bioprinting, there are several drawbacks of current bioinks and printing methodologies that limit the ability to print elastic and highly vascularized tissues. In particular, fabrication of complex biomimetic structure that are entirely based on 3D bioprinting is still challenging primarily due to the lack of suitable bioinks with high printability, biocompatibility, biomimicry, and proper mechanical properties. To address these shortcomings, in this work the use of recombinant human tropoelastin as a highly biocompatible and elastic bioink for 3D printing of complex soft tissues is demonstrated. As proof of the concept, vascularized cardiac constructs are bioprinted and their functions are assessed in vitro and in vivo. The printed constructs demonstrate endothelium barrier function and spontaneous beating of cardiac muscle cells, which are important functions of cardiac tissue in vivo. Furthermore, the printed construct elicits minimal inflammatory responses, and is shown to be efficiently biodegraded in vivo when implanted subcutaneously in rats. Taken together, these results demonstrate the potential of the elastic bioink for printing 3D functional cardiac tissues, which can eventually be used for cardiac tissue replacement.

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“…On the other hand, extrusion-based 3D printing offers a relatively quick way to generate 3D structured hydrogel objects in the centimeter range without the need for molds [10,11,12], as used, e.g., in injection molding [13]. Looking at materials used for hydrogel formulations in general, both bio-based polymers like hyaluronic acid [14,15], gelatin [16,17], and alginate [18,19] as well as synthetic polymers like polyacrylamide (PAAm) [20], polyvinyl alcohol (PVA) [21], and poly(ethylene glycol) (PEG) [22,23] have been used in various applications and were partly formulated for extrusion-based 3D printing as well [24,25,26]. In particular, the readily available PEG can be obtained in various polymer architectures and with various end-group functionalities.…”

Section: Introductionmentioning

confidence: 99%

Extrusion-Based 3D Printing of Poly(ethylene glycol) Diacrylate Hydrogels Containing Positively and Negatively Charged Groups

Joas

Tovar

Celik

et al. 2018

Gels

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Hydrogels are an interesting class of materials used in extrusion-based 3D printing, e.g., for drug delivery or tissue engineering. However, new hydrogel formulations for 3D printing as well as a detailed understanding of crucial formulation properties for 3D printing are needed. In this contribution, hydrogels based on poly(ethylene glycol) diacrylate (PEG-DA) and the charged monomers 3-sulfopropyl acrylate and [2-(acryloyloxy)ethyl]trimethylammonium chloride are formulated for 3D printing, together with Poloxamer 407 (P407). Chemical curing of formulations with PEG-DA and up to 5% (w/w) of the charged monomers was possible without difficulty. Through careful examination of the rheological properties of the non-cured formulations, it was found that flow properties of formulations with a high P407 concentration of 22.5% (w/w) possessed yield stresses well above 100 Pa together with pronounced shear thinning behavior. Thus, those formulations could be processed by 3D printing, as demonstrated by the generation of pyramidal objects. Modelling of the flow profile during 3D printing suggests that a plug-like laminar flow is prevalent inside the printer capillary. Under such circumstances, fast recovery of a high vicosity after material deposition might not be necessary to guarantee shape fidelity because the majority of the 3D printed volume does not face any relevant shear stress during printing.

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Influence of shear thinning and material flow on robotic dispensing of poly(ethylene glycol) diacrylate/poloxamer 407 hydrogels

Cited by 24 publications

References 31 publications

Assessment methodologies for extrusion-based bioink printability

Assessment methodologies for extrusion-based bioink printability

Human‐Recombinant‐Elastin‐Based Bioinks for 3D Bioprinting of Vascularized Soft Tissues

Extrusion-Based 3D Printing of Poly(ethylene glycol) Diacrylate Hydrogels Containing Positively and Negatively Charged Groups

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