Muscle‐Inspired Highly Anisotropic, Strong, Ion‐Conductive Hydrogels

Kong, Weiqing; Wang, Chengwei; Jia, Chao; Kuang, Yudi; Pastel, Glenn; Chen, Chaoji; Chen, Gegu; He, Shuaiming; Huang, Hao; Zhang, Jianhua; Wang, Sha; Hu, Liangbing

doi:10.1002/adma.201801934

Cited by 455 publications

(329 citation statements)

References 65 publications

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“…To compare our results with existing hydrogels and biological tissues, we summarize the nominal tensile strengths, Young's moduli, fatigue thresholds, and water contents of various tough hydrogels (24,25,28,40,(45)(46)(47)(48)(49) and biological tissues (1) (47), fiber-reinforced hydrogel composites (45,51), wood hydrogels (46), and constrained air-drying hydrogels (40) are in the range of 0.1 to 10 (Fig. 3E).…”

Section: Significancementioning

confidence: 99%

Muscle-like fatigue-resistant hydrogels by mechanical training

Lin

Liu

et al. 2019

Proc. Natl. Acad. Sci. U.S.A.

373

412

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Skeletal muscles possess the combinational properties of high fatigue resistance (1,000 J/m 2 ), high strength (1 MPa), low Young's modulus (100 kPa), and high water content (70 to 80 wt %), which have not been achieved in synthetic hydrogels. The muscle-like properties are highly desirable for hydrogels' nascent applications in load-bearing artificial tissues and soft devices. Here, we propose a strategy of mechanical training to achieve the aligned nanofibrillar architectures of skeletal muscles in synthetic hydrogels, resulting in the combinational muscle-like properties. These properties are obtained through the training-induced alignment of nanofibrils, without additional chemical modifications or additives. In situ confocal microscopy of the hydrogels' fracturing processes reveals that the fatigue resistance results from the crack pinning by the aligned nanofibrils, which require much higher energy to fracture than the corresponding amorphous polymer chains. This strategy is particularly applicable for 3D-printed microstructures of hydrogels, in which we can achieve isotropically fatigue-resistant, strong yet compliant properties.polyvinyl alcohol | anti-fatigue-fracture | freeze−thaw | prestretch | 3D printing B iological load-bearing tissues such as skeletal muscles commonly show J-shaped stress−strain behaviors with low Young's modulus and high strength on the order of 100 kPa and 1 MPa, respectively (1, 2). Moreover, despite their high water content of around 75 wt % (3), skeletal muscles can sustain a high stress of 1 MPa over 1 million cycles per year, with a fatigue resistance over 1,000 J/m 2 (4). The combinational properties of skeletal muscles (i.e., high fatigue resistance, high strength, superior compliance, and high water content) are highly desirable for hydrogels' nascent applications in soft biological devices, such as load-bearing artificial tissues (5), hydrogel bioelectronics (6-9), hydrogel optical fibers (10, 11), ingestible hydrogel devices (12), robust hydrogel coatings on medical devices (13-17), and hydrogel soft robots (18)(19)(20).Although various molecular and macromolecular engineering approaches have replicated parts of biological muscles' characteristics, none of them can synergistically replicate all these attributes in one single material system (SI Appendix, Table S1). For example, both strain-stiffening hydrogels (21, 22) and bottle brush polymer networks (1, 23) can mimic the J-shaped stress− strain behaviors, but their fracture toughness is still much lower than biological tissues, since no significant mechanical dissipation has been introduced in these materials for toughness enhancement. Although various tough hydrogels (24-26) have been developed by incorporating various dissipation mechanisms, they are susceptible to fatigue fracture under repeated mechanical loads, since the resistance to fatigue crack propagation after prolonged repeated mechanical loads is the energy required to fracture a single layer of polymer chains, unaffected by the additional dissipation (2...

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Section: Significancementioning

confidence: 99%

Muscle-like fatigue-resistant hydrogels by mechanical training

Lin

Liu

et al. 2019

Proc. Natl. Acad. Sci. U.S.A.

373

412

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“…Finally, nowadays it is realized that the natural cellular environment is not uniform but contains anisotropic structures that provide directionality and guidance . In order to achieve this next level of complexity composite hydrogels are prepared . Trying to meet all these demands of increasing complexity still a lot remains to be explored.…”

Section: Introductionmentioning

confidence: 99%

A Hybrid Peptide Amphiphile Fiber PEG Hydrogel Matrix for 3D Cell Culture

Zhan

Löwik

2019

Adv Funct Materials

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Since the traditional 2D surface for cell growth has been shown to be increasingly insufficient in contemporary cell biology, more and more research is performed on 3D matrices that can better represent the natural extracellular matrix (ECM) in many aspects. To create such a complex nonuniform 3D matrix, four-armed polyethylene glycol with azides and (1R,8S,9S)-bicyclo[6.1.0]non-4-yn-9-yl groups is functionalized to form the hydrogel basis. Together with these, a matrix metalloproteinase cleavable peptide sequence as a functional motif is also built in to add degradability to the hydrogel. In addition, self-assembled peptide amphiphile (PA) fibers containing a cellular binding peptide sequence (RGDS) are encapsulated in the hydrogel to mimic the natural fibrous structure of the ECM and to stimulate cell adhesion. Rheology studies confirm that the polymer dissolved in the PA fiber solution forms a stable hydrogel with acceptable mechanical properties (G′ = 3.8 kPa). In addition, it is shown that this hydrogel network is degradable under the action of a metalloproteinase enzyme. Finally, the hybrid hydrogel is used to culture and it is demonstrated that both HeLa cells and human mesenchymal stem cells show adherence, good viability, and a well-spread shape inside the hybrid hydrogel after 5 days of incubation when all components are present.

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“…Hu et al. reported highly anisotropic and ion‐conductive wood‐based hydrogels with high tensile strength of 36 MPa along the longitudinal direction . By utilizing the electrical field, magnetic field, and other advanced engineering technologies including 3D printing and electrospinning, hydrogel actuators have achieved great improvement in motion amplitude and response speed .…”

Section: Introductionmentioning

confidence: 99%

Multi‐Responsive Bilayer Hydrogel Actuators with Programmable and Precisely Tunable Motions

Wang

Huang

Liu

et al. 2019

Macro Chemistry & Physics

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Multi‐responsive hydrogel actuators show promising applications for soft robotics, biomedical engineering, and artificial muscles, but the uncontrollable nature of their motions poses a barrier to practical applications. Herein, a novel type of bilayer hydrogel actuators (BHAs) is presented comprising of a poly(N‐isopropylacrylamide) (PNIPAm) and a poly (N‐hydroxyethyl acrylamide) (PHEAm) hydrogel layer with various compositions, which demonstrate thermal‐responsive and novel solvent‐responsive actuation under water or within solvents. These BHAs exhibit a wide range of regulable bidirectional motions due to the simultaneous co‐nonsolvency property of PNIPAm and the shrinking behavior of PHEAm in ethanol/water mixtures with various ethanol contents. By adjusting the compositions of ethanol/water mixtures, the bending directions and amplitudes of BHAs are precisely regulable and the curvatures of actuators are tunable between −0.34 and 0.3. Because of the temperature‐responsive character of PNIPAm, BHAs fulfilled thermal‐driven motions to lift items. By reinforcing PHEAm layers with cellulose nanocrystals (CNCs) or CNCs bearing methacylamide moieties on the surface, the weight‐lifting capability of BHAs is highly improved to 18 times the weight of their own polymer weights. This design concept with bilayer structures provides a new strategy for the construction of precisely regulable hydrogel actuators, which allows using solvents to exactly control their motions.

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Muscle‐Inspired Highly Anisotropic, Strong, Ion‐Conductive Hydrogels

Cited by 455 publications

References 65 publications

Muscle-like fatigue-resistant hydrogels by mechanical training

Muscle-like fatigue-resistant hydrogels by mechanical training

A Hybrid Peptide Amphiphile Fiber PEG Hydrogel Matrix for 3D Cell Culture

Multi‐Responsive Bilayer Hydrogel Actuators with Programmable and Precisely Tunable Motions

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