An official website of the United States government
Abstract Engineered living materials (ELMs) are an emerging class of biohybrid materials with genetically programmable functionalities. Integrating ELMs with 3D bioprinting synergizes their biological programmability with the geometry‐driven functionality of 3D‐printed constructs, transforming these materials into practical products and engineering solutions. This integration also introduces a new paradigm in additive manufacturing that harnesses the “livingness” of encapsulated microorganisms as an active element in the fabrication process to create adaptive and evolving 3D constructs. This Perspective presents recent advances in 3D bioprinting and discusses current developments at the intersection of 3D bioprinting and ELMs. It highlights opportunities at the interface of these two emerging fields, including understanding the interactions between living and nonliving components of ELMs for bioink design, incorporating synthetic biology into bioprinting workflows, utilizing microbial growth as a postprinting fabrication process, and integrating shape‐morphing materials to enable the 4D printing of ELMs.
more »
« less
This content will become publicly available on September 1, 2026
Self-Supported Printing of Gelatin Composite-Based Engineered Living Materials
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.
more »
« less
- Award ID(s):
- 2233814
- PAR ID:
- 10630557
- Publisher / Repository:
- ASME
- Date Published:
- Journal Name:
- Journal of Manufacturing Science and Engineering
- Volume:
- 147
- Issue:
- 9
- ISSN:
- 1087-1357
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
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.more » « less
-
Abstract The encapsulation of cells within gel‐phase materials to form bioinks offers distinct advantages for next‐generation 3D bioprinting. 3D bioprinting has emerged as a promising tool for patterning cells, but the technology remains limited in its ability to produce biofunctional, tissue‐like constructs due to a dearth of materials suitable for bioinks. While early demonstrations commonly used viscous polymers optimized for printability, these materials often lacked cell compatibility and biological functionality. In response, advanced materials that exist in the gel phase during the entire printing process are being developed, since hydrogels are uniquely positioned to both protect cells during extrusion and provide biological signals to embedded cells as the construct matures during culture. Here, an overview of the design considerations for gel‐phase materials as bioinks is presented, with a focus on their mechanical, biochemical, and dynamic gel properties. Current challenges and opportunities that arise due to the fact that bioprinted constructs are active, living hydrogels composed of both acellular and cellular components are also evaluated. Engineering hydrogels with consideration of cells as an intrinsic component of the printed bioink will enable control over the evolution of the living construct after printing to achieve greater biofunctionality.more » « less
-
The generation of 3D tissue constructs with multiple cell types and matching mechanical properties remains a challenge in cardiac tissue engineering. Recently, 3D bioprinting has become a powerful tool to achieve these goals. Decellularized extracellular matrix (dECM) is a common scaffold material due to providing a native biochemical environment. Unfortunately, dECM’s low mechanical stability prevents usage for bioprinting applications alone. In this study, we developed bioinks composed of decellularized human heart ECM (dhECM) with either gelatin methacryloyl (GelMA) or GelMA-methacrylated hyaluronic acid (MeHA) hydrogels dual crosslinked with UV light and microbial transglutaminase (mTGase). We characterized the bioinks’ mechanical, rheological, swelling, printability, and biocompatibility properties. Composite GelMA–MeHA–dhECM (GME) hydrogels demonstrated improved mechanical properties by an order of magnitude compared to the GelMA–dhECM (GE) hydrogels. All hydrogels were extrudable and compatible with human induced pluripotent stem cell derived cardiomyocytes (iCMs) and human cardiac fibroblasts (hCFs). Tissue-like beating of the printed constructs with striated sarcomeric alpha-actinin and connexin 43 expression was observed. The order of magnitude difference between the elastic modulus of these hydrogel composites offers applications in in vitro modeling of the myocardial infarct boundary. Here, as a proof of concept, we created an infarct boundary region with control over the mechanical properties along with the cellular and macromolecular content through printing iCMs with GE bioink and hCFs with GME bioink.more » « less
-
There is a growing demand for bone graft substitutes that mimic the extracellular matrix properties of the native bone tissue to enhance stem cell osteogenesis. Composite hydrogels containing human bone allograft particles are particularly interesting due to inherent bioactivity of the allograft tissue. Here, we report a novel photocurable composite hydrogel bioink for bone tissue engineering. Our composite bioink is formulated by incorporating human allograft bone particles in a methacrylated alginate formulation to enhance adult human mesenchymal stem cell (hMSC) osteogenesis. Detailed rheology and printability studies confirm suitability of our composite bioinks for extrusion-based 3D bioprinting technology. In vitro studies reveal high cell viability (~90%) for hMSCs up to 28 days of culture within 3D bioprinted composite scaffolds. When cultured within bioprinted composite scaffolds, hMSCs show significantly enhanced osteogenic differentiation as compared to neat scaffolds based on alkaline phosphatase activity, calcium deposition, and osteocalcin expression.more » « less
