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The emergence of engineered living materials (ELMs) has led to the development of functional composites by combining living microorganisms with nonliving components, particularly hydrogels. Hydrogels, which mimic the extracellular matrix, support microbial growth by providing essential nutrients and promoting cell adhesion, making them ideal for ELM production. However, hydrogel-based materials often face challenges in three-dimensional printing due to poor structural integrity and limited printability, frequently requiring additional processes, precise control, and/or material modifications to enhance their printing performance. This study focuses on developing a microorganism-laden gelatin microgel and gelatin solution-based composite bioink for self-supported printing of ELMs, enhanced via microbial-induced calcium carbonate precipitation. Gelatin microgels are utilized as rheology modifiers, enabling the yield-stress fluid behavior of the bioink for improved printability and postprinting shape retention, while transglutaminase enzymatically cross-links printed structures completely, resulting in good printability. Furthermore, Sporosarcina pasteurii in the bioink enables calcium carbonate deposition during postprinting culturing, forming robust, biomineralized structures. Fabricated samples are found to have significant successful mineral deposition with over 50 wt% calcium carbonate content, and they exhibit compressive strengths of up to 1.4 MPa. This approach offers a cost-effective, energy-efficient method for creating high-strength, biocompatible biocomposites with potential applications such as bone tissue engineering, coral restoration, and sustainable building development.
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Effects of transglutaminase cross-linking process on printability of gelatin microgel-gelatin solution composite bioink
Abstract Three-dimensional (3D) bioprinting has emerged as a powerful engineering approach for various tissue engineering applications, particularly for the development of 3D cellular structures with unique mechanical and/or biological properties. For the jammed gelatin microgel-gelatin solution composite bioink, comprising a discrete phase of microgels (enzymatically gelled gelatin microgels) and a cross-linkable continuous gelatin precursor solution-based phase containing transglutaminase (TG), its rheological properties and printability change gradually due to the TG enzyme-induced cross-linking process. The objective of this study is to establish a direct mapping between the printability of the gelatin microgel-gelatin solution based cross-linkable composite bioink and the TG concentration and cross-linking time, respectively. Due to the inclusion of TG in the composite bioink, the bioink starts cross-linking once prepared and is usually prepared right before a printing process. Herein, the bioink printability is evaluated based on the three metrics: injectability, feature formability, and process-induced cell injury. In this study, the rheological properties such as the storage modulus and viscosity have been first systematically investigated and predicted at different TG concentrations and times during the cross-linking process using the first-order cross-linking kinetics model. The storage modulus and viscosity have been satisfactorily modeled as exponential functions of the TG concentration and time with an experimentally calibrated cross-linking kinetic rate constant. Furthermore, the injectability, feature formability, and process-induced cell injury have been successfully correlated to the TG concentration and cross-linking time via the storage modulus, viscosity, and/or process-induced shear stress. By combing the good injectability, good feature formability, and satisfactory cell viability zones, a good printability zone (1.65, 0.61, and 0.31 h for the composite bioinks with 1.00, 2.00, and 4.00% w/v TG, respectively) has been established during the printing of mouse fibroblast-based 2% gelatin B microgel-3% gelatin B solution composite bioink. This printability zone approach can be extended to the use of other cross-linkable bioinks for bioprinting applications.
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- Award ID(s):
- 1762941
- PAR ID:
- 10323471
- Date Published:
- Journal Name:
- Biofabrication
- Volume:
- 14
- Issue:
- 1
- ISSN:
- 1758-5082
- Page Range / eLocation ID:
- 015014
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
-
Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1088/1758-5090/ac3d75
