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Brunel LG, Christakopoulos F, Kilian D, Cai B, Hull SM, Myung D, Heilshorn SC. Embedded 3D Bioprinting of Collagen Inks into Microgel Baths to Control Hydrogel Microstructure and Cell Spreading. Adv Healthc Mater 2023:e2303325. [PMID: 38134346 DOI: 10.1002/adhm.202303325] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2023] [Revised: 12/14/2023] [Indexed: 12/24/2023]
Abstract
Microextrusion-based 3D bioprinting into support baths has emerged as a promising technique to pattern soft biomaterials into complex, macroscopic structures. It is hypothesized that interactions between inks and support baths, which are often composed of granular microgels, can be modulated to control the microscopic structure within these macroscopic-printed constructs. Using printed collagen bioinks crosslinked either through physical self-assembly or bioorthogonal covalent chemistry, it is demonstrated that microscopic porosity is introduced into collagen inks printed into microgel support baths but not bulk gel support baths. The overall porosity is governed by the ratio between the ink's shear viscosity and the microgel support bath's zero-shear viscosity. By adjusting the flow rate during extrusion, the ink's shear viscosity is modulated, thus controlling the extent of microscopic porosity independent of the ink composition. For covalently crosslinked collagen, printing into support baths comprised of gelatin microgels (15-50 µm) results in large pores (≈40 µm) that allow human corneal mesenchymal stromal cells (MSCs) to readily spread, while control samples of cast collagen or collagen printed in non-granular support baths do not allow cell spreading. Taken together, these data demonstrate a new method to impart controlled microscale porosity into 3D printed hydrogels using granular microgel support baths.
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Affiliation(s)
- Lucia G Brunel
- Department of Chemical Engineering, Stanford University, Stanford, CA, 94305, USA
| | - Fotis Christakopoulos
- Department of Materials Science and Engineering, Stanford University, Stanford, CA, 94305, USA
| | - David Kilian
- Department of Materials Science and Engineering, Stanford University, Stanford, CA, 94305, USA
| | - Betty Cai
- Department of Materials Science and Engineering, Stanford University, Stanford, CA, 94305, USA
| | - Sarah M Hull
- Department of Chemical Engineering, Stanford University, Stanford, CA, 94305, USA
| | - David Myung
- Department of Chemical Engineering, Stanford University, Stanford, CA, 94305, USA
- Department of Ophthalmology, Byers Eye Institute, Stanford University School of Medicine, Palo Alto, CA, 94303, USA
- VA Palo Alto Health Care System, Palo Alto, CA, 94304, USA
| | - Sarah C Heilshorn
- Department of Materials Science and Engineering, Stanford University, Stanford, CA, 94305, USA
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Romberg SK, Kotula AP. Simultaneous rheology and cure kinetics dictate thermal post-curing of thermoset composite resins for material extrusion. ADDITIVE MANUFACTURING 2023; 71:10.1016/j.addma.2023.103589. [PMID: 37427308 PMCID: PMC10327424 DOI: 10.1016/j.addma.2023.103589] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/11/2023]
Abstract
Thermoset composites are excellent candidates for material extrusion because they shear thin during extrusion but retain their shape once deposited via a yield stress. However, thermal post-curing is often required to solidify these materials, which can destabilize printed parts. Elevated temperatures can decrease the rheological properties responsible for stabilizing the printed structure before crosslinking solidifies the material. These properties, namely the storage modulus and yield stress, must therefore be characterized as a function of temperature and extent of reaction for various filler loadings. This work utilizes rheo-Raman spectroscopy to measure the storage modulus and dynamic yield stress as a function of temperature and conversion in epoxy-amine resins with fumed silica mass fractions up to 10 %. Both rheological properties are sensitive to conversion and particle loading, but only the dynamic yield stress is reduced by elevated temperatures early in the cure. Notably, the dynamic yield stress increases with conversion well before the chemical gel point. These findings motivate a two-step cure protocol that starts at a low temperature to mitigate the drop in dynamic yield stress, then ramps up to a high temperature when the dynamic yield stress is no longer at risk of decreasing to rapidly drive conversion to near completion. The results suggests that structural stability can be improved without resorting to increasing filler content, which limits control over the final properties, laying the groundwork for future studies to evaluate the stability improvements provided by the multi-step curing schedules.
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Affiliation(s)
- Stian K Romberg
- Materials Science and Engineering Division, National Institute of Standards and Technology, Gaithersburg, MD 20899
| | - Anthony P Kotula
- Materials Science and Engineering Division, National Institute of Standards and Technology, Gaithersburg, MD 20899
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Cernencu AI, Ioniță M. The current state of the art in gellan-based printing inks in tissue engineering. Carbohydr Polym 2023; 309:120676. [PMID: 36906360 DOI: 10.1016/j.carbpol.2023.120676] [Citation(s) in RCA: 12] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2022] [Revised: 02/02/2023] [Accepted: 02/03/2023] [Indexed: 02/10/2023]
Abstract
With the advancement of enhanced fabrication technologies, specifically 3D printing, it is now possible to build artificial tissue for personalized healing. However, inks developed from polymers often fail to meet expectations in terms of mechanical strength, scaffold integrity, and the stimulation of tissue formation. Developing new printable formulations as well as adapting existing printing methods is an essential aspect of contemporary biofabrication research. In order to push the boundaries of the printability window, various strategies have been developed employing gellan gum. This has resulted in major breakthroughs in the development of 3D hydrogels scaffolds that exhibit significant resemblance to genuine tissues and enables the fabrication of more complex systems. In light of the many uses of gellan gum, the purpose of this paper is to provide a synopsis of the printable ink designs drawing attention to the various compositions and fabrication approaches that may be used for tuning the properties of 3D printed hydrogels for tissue engineering applications. The purpose of this article is to outline the development of gellan-based 3D printing inks and to encourage research by highlighting the possible applications of gellan gum.
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Affiliation(s)
- Alexandra I Cernencu
- Advanced Polymer Materials Group, University Politehnica of Bucharest, SplaiulIndependenței, 313, 060042, Bucharest, Romania
| | - Mariana Ioniță
- Advanced Polymer Materials Group, University Politehnica of Bucharest, SplaiulIndependenței, 313, 060042, Bucharest, Romania; Faculty of Medical Engineering, University Politehnica of Bucharest, Bucharest 011061, Romania.
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Honaryar H, Amirfattahi S, Niroobakhsh Z. Associative Liquid-In-Liquid 3D Printing Techniques for Freeform Fabrication of Soft Matter. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2023; 19:e2206524. [PMID: 36670057 DOI: 10.1002/smll.202206524] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/22/2022] [Revised: 12/19/2022] [Indexed: 06/17/2023]
Abstract
Shaping soft materials into prescribed 3D complex designs has been challenging yet feasible using various 3D printing technologies. For a broader range of soft matters to be printable, liquid-in-liquid 3D printing techniques have emerged in which an ink phase is printed into 3D constructs within a bath. Most of the attention in this field has been focused on using a support bath with favorable rheology (i.e., shear-thinning behavior) which limits the selection of materials, impeding the broad application of such techniques. However, a growing body of work has begun to leverage the interaction or association of the two involved phases (specifically at the liquid-liquid interface) to fabricate complex constructs from a myriad of soft materials with practical structural, mechanical, optical, magnetic, and communicative properties. This review article has provided an overview of the studies on such associative liquid-in-liquid 3D printing techniques along with their fundamentals, underlying mechanisms, various characterization techniques used for ensuring the structural stability, and practical properties of prints. Also, the future paths with the potential applications are discussed.
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Affiliation(s)
- Houman Honaryar
- Division of Energy, Matter, and Systems, School of Science and Engineering, University of Missouri-Kansas City, Kansas City, MO, 64110, USA
| | - Saba Amirfattahi
- Division of Energy, Matter, and Systems, School of Science and Engineering, University of Missouri-Kansas City, Kansas City, MO, 64110, USA
| | - Zahra Niroobakhsh
- Division of Energy, Matter, and Systems, School of Science and Engineering, University of Missouri-Kansas City, Kansas City, MO, 64110, USA
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Weeks RD, Truby RL, Uzel SGM, Lewis JA. Embedded 3D Printing of Multimaterial Polymer Lattices via Graph-Based Print Path Planning. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2023; 35:e2206958. [PMID: 36404106 DOI: 10.1002/adma.202206958] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2022] [Revised: 11/12/2022] [Indexed: 06/16/2023]
Abstract
Recent advances in computational design and 3D printing enable the fabrication of polymer lattices with high strength-to-weight ratio and tailored mechanics. To date, 3D lattices composed of monolithic materials have primarily been constructed due to limitations associated with most commercial 3D printing platforms. Here, freeform fabrication of multi-material polymer lattices via embedded three-dimensional (EMB3D) printing is demonstrated. An algorithm is developed first that generates print paths for each target lattice based on graph theory. The effects of ink rheology on filamentary printing and the effects of the print path on resultant mechanical properties are then investigated. By co-printing multiple materials with different mechanical properties, a broad range of periodic and stochastic lattices with tailored mechanical responses can be realized opening new avenues for constructing architected matter.
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Affiliation(s)
- Robert D Weeks
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, 02138, USA
| | - Ryan L Truby
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, 02138, USA
| | - Sebastien G M Uzel
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, 02138, USA
- Wyss Institute for Biologically Inspired Engineering, Harvard University, Cambridge, MA, 02138, USA
| | - Jennifer A Lewis
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, 02138, USA
- Wyss Institute for Biologically Inspired Engineering, Harvard University, Cambridge, MA, 02138, USA
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Zhang C, Liao E, Li C, Zhang Y, Chen Y, Lu A, Liu Y, Geng C. 3D Printed Silicones with Shape Morphing and Low-Temperature Ultraelasticity. ACS APPLIED MATERIALS & INTERFACES 2023; 15:4549-4558. [PMID: 36642888 DOI: 10.1021/acsami.2c20392] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
3D printed silicones have demonstrated great potential in diverse areas by combining the advantageous physiochemical properties of silicones with the unparalleled design freedom of additive manufacturing. However, their low-temperature performance, which is of particular importance for polar and space applications, has not been addressed. Herein, a 3D printed silicone foam with unprecedented low-temperature elasticity is presented, which is featured with extraordinary fatigue resistance, excellent shape recovery, and energy-absorbing capability down to a low temperature of -60 °C after extreme compression (an intensive load of over 66000 times its own weight). The foam is achieved by direct writing of a phenyl silicone-based pseudoplastic ink embedded with sodium chloride as sacrificial template. During the water immersion process to create pores in the printed filaments, a unique osmotic pressure-driven shape morphing strategy is also reported, which offers an attractive alternative to traditional 4D printed hydrogels in virtue of the favorable mechanical robustness of the silicone material. The underlying mechanisms for shape morphing and low-temperature elasticity are discussed in detail.
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Affiliation(s)
- Chenyang Zhang
- Institute of Chemical Materials, China Academy of Engineering Physics (CAEP), Mianyang 621900, China
| | - Enze Liao
- Institute of Chemical Materials, China Academy of Engineering Physics (CAEP), Mianyang 621900, China
| | - Changlin Li
- Institute of Chemical Materials, China Academy of Engineering Physics (CAEP), Mianyang 621900, China
| | - Yaling Zhang
- Institute of Chemical Materials, China Academy of Engineering Physics (CAEP), Mianyang 621900, China
| | | | - Ai Lu
- Institute of Chemical Materials, China Academy of Engineering Physics (CAEP), Mianyang 621900, China
| | | | - Chengzhen Geng
- Institute of Chemical Materials, China Academy of Engineering Physics (CAEP), Mianyang 621900, China
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