Hydrogels hold much promise for 3D printing of functional living materials; however, challenges remain in tailoring mechanical robustness as well as biological performance. In addressing this challenge, the modular synthesis of functional hydrogels from 3‐arm diblock copolypeptide stars composed of an inner poly(
This content will become publicly available on July 10, 2024
Shear‐recoverable hydrogels based on block copolypeptides with rapid self‐recovery hold potential in extrudable and injectable 3D‐printing applications. In this work, a series of 3‐arm star‐shaped block copolypeptides composed of an inner hydrophilic poly(
- NSF-PAR ID:
- 10442142
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Small
- Volume:
- 19
- Issue:
- 50
- ISSN:
- 1613-6810
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
more » « less
Abstract l ‐glutamate) domain and outer poly(l ‐tyrosine) or poly(l ‐valine) blocks is described. Physical crosslinking due to ß‐sheet assembly of these star block copolymers gives mechanical stability during extrusion printing and the selective incorporation of methacrylate units allows for subsequent photocrosslinking to occur under biocompatible conditions. This permits direct ink writing (DIW) printing of bacteria‐based mixtures leading to 3D objects with high fidelity and excellent bacterial viability. The tunable stiffness of different copolypeptide networks enables control over proliferation and colony formation for embeddedEscherichia coli bacteria as demonstrated via isopropyl ß‐d ‐1‐thiogalactopyranoside (IPTG) induction of green fluorescent protein (GFP) expression. This translation of molecular structure to network properties highlights the versatility of these polypeptide hydrogel systems with the combination of writable structures and biological activity illustrating the future potential of these 3D‐printed biocomposites. -
null (Ed.)Purpose This paper aims to summarize the up-to-date research performed on combinations of various biofibers and resin systems used in different three-dimensional (3D) printing technologies, including powder-based, material extrusion, solid-sheet and liquid-based systems. Detailed information about each process, including materials used and process design, are described, with the resultant products’ mechanical properties compared with those of 3D-printed parts produced from pure resin or different material combinations. In most processes introduced in this paper, biofibers are beneficial in improving the mechanical properties of 3D-printed parts and the biodegradability of the parts made using these green materials is also greatly improved. However, research on 3D printing of biofiber-reinforced composites is still far from complete, and there are still many further studies and research areas that could be explored in the future. Design/methodology/approach The paper starts with an overview of the current scenario of the composite manufacturing industry and then the problems of advanced composite materials are pointed out, followed by an introduction of biocomposites. The main body of the paper covers literature reviews of recently emerged 3D printing technologies that were applied to biofiber-reinforced composite materials. This part is classified into subsections based on the form of the starting materials used in the 3D printing process. A comprehensive conclusion is drawn at the end of the paper summarizing the findings by the authors. Findings Most of the biofiber-reinforced 3D-printed products exhibited improved mechanical properties than products printed using pure resin, indicating that biofibers are good replacements for synthetic ones. However, synthetic fibers are far from being completely replaced by biofibers due to several of their disadvantages including higher moisture absorbance, lower thermal stability and mechanical properties. Many studies are being performed to solve these problems, yet there are still some 3D printing technologies in which research concerning biofiber-reinforced composite parts is quite limited. This paper unveils potential research directions that would further develop 3D printing in a sustainable manner. Originality/value This paper is a summary of attempts to use biofibers as reinforcements together with different resin systems as the starting material for 3D printing processes, and most of the currently available 3D printing techniques are included herein. All of these attempts are solutions to some principal problems with current 3D printing processes such as the limit in the variety of materials and the poor mechanical performance of 3D printed parts. Various types of biofibers are involved in these studies. This paper unveils potential research directions that would further widen the use of biofibers in 3D printing in a sustainable manner.more » « less
-
more » « less
Abstract A rapid and facile approach to predictably control integration between two materials with divergent properties is introduced. Programmed integration between photopolymerizable soft and stiff hydrogels is investigated due to their promise in applications such as tissue engineering where heterogeneous properties are often desired. The spatial control afforded by grayscale 3D printing is leveraged to define regions at the interface that permit diffusive transport of a second material in‐filled into the 3D printed part. The printing parameters (i.e., effective exposure dose) for the resin are correlated directly to mesh size to achieve controlled diffusion. Applying this information to grayscale exposures leads to a range of distances over which integration is achieved with high fidelity. A prescribed finite distance of integration between soft and stiff hydrogels leads to a 33% increase in strain to failure under tensile testing and eliminates failure at the interface. The feasibility of this approach is demonstrated in a layer‐by‐layer 3D printed part fabricated by stereolithography, which is subsequently infilled with a soft hydrogel containing osteoblastic cells. In summary, this approach holds promise for applications where integration of multiple materials and living cells is needed by allowing precise control over integration and reducing mechanical failure at contrasting material interfaces.
-
more » « less
Abstract Hydrogels are the focus of extensive research due to their potential use in fields including biomedical, pharmaceutical, biosensors, and cosmetics. However, the general weak mechanical properties of hydrogels limit their utility. Here, pristine silk fibroin (SF) hydrogels with excellent mechanical properties are generated via a binary‐solvent‐induced conformation transition (BSICT) strategy. In this method, the conformational transition of SF is regulated by moderate binary solvent diffusion and SF/solvent interactions. β‐sheet formation serves as the physical crosslinks that connect disparate protein chains to form continuous 3D hydrogel networks, avoiding complex chemical and/or physical treatments. The Young's modulus of these new BSICT–SF hydrogels can reach up to 6.5 ± 0.2 MPa, tens to hundreds of times higher than that of conventional hydrogels (0.01–0.1 MPa). These new materials fill the “empty soft materials' space” in the elastic modulus/strain Ashby plot. More remarkably, the BSICT–SF hydrogels can be processed into different constructions through different polymer and/or metal‐based processing techniques, such as molding, laser cutting, and machining. Thus, these new hydrogel systems exhibit potential utility in many biomedical and engineering fields.
-
more » « less
Abstract Polyvinyl alcohol (PVA) is a water-soluble synthetic polymer that can be used to make hydrogels for biomedical applications as well as biodegradable bags and films; however, compared to other plastics currently used for containers, it lacks mechanical strength, thermal stability, and can easily absorb water from humid environments. Although mechanical improvement has been observed by blending PVA with collagen in a hybrid hydrogel, there is a lack of fundamental understanding of the molecular mechanism, and it is not clear whether the improvement is limited to a hydrated state. Here, using classical molecular dynamics simulations based on fully atomistic models, we develop the equilibrated molecular structure of PVA with collagen and characterize its mechanics. We show that by interacting with a collagen molecule, PVA is equilibrated to a more ordered structure with each residue interacting with the near neighbors by forming more hydrogen bonds locally, making the structure stiffer than pure PVA. The structure shows higher thermal stability before melting, as well as higher rigidity in water. Our results provide the mechanism of the mechanical advantages of hybrid PVA-collagen polymer. The study demonstrates that the structure and mechanics of a synthetic polymer can be tuned by a tiny amount of a natural polymer at the molecular interface. Moreover, it may shed light on identifying a way to improve the mechanics of biodegradable polymer materials without adding much cost, which is crucial for environmental safety.
Impact statement Blending natural and synthetic polymers (e.g., polyvinyl alcohol [PVA] and collagen in a hybrid hydrogel) has shown advantages in polymer mechanics, but there is a lack of fundamental understanding. Using molecular dynamics (MD) simulations based on fully atomistic models, we develop the equilibrated structure of the PVA with collagen and characterize its mechanics. We show that by interacting with a collagen molecule, PVA is equilibrated to a more ordered structure with each residue interacting with the near neighbors by forming more H-bonds locally and the structure is stiffer than pure PVA. Moreover, the structure shows a higher thermal stability before the melting point of PVA, as well as higher rigidity in water. Our results demonstrate that the structure and mechanics of a synthetic polymer can be tuned by a tiny amount of a natural polymer at the molecular interface. It provides the mechanism of the mechanical advantages as experimentally observed. This study paves the way for the multiscale modeling and mechanical design of the hybrid polymer material. It sheds light on identifying a way to improve the mechanics of biodegradable materials without adding much cost for both material functionality and environmental safety.
Graphical abstract
