Protein‐Based Hydrogels that Actuate Self‐Folding Systems

Gomes, Conor M.; Liu, Chang; Paten, Jeffrey A.; Felton, Samuel M.; Deravi, Leila F.

doi:10.1002/adfm.201805777

Cited by 18 publications

(15 citation statements)

References 57 publications

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“…This approach demonstrates that incubation of polyelectrolyte with protein hydrogels does not only increase the attainable stiffness and tunability but also allow hydrogels to operate in a stimuli-responsive manner. Other systems, based on fibrillar proteins such as collagen, use swelling and deswelling to actuate macroscopic movements 42 . Our system is unique, as it is utilizing the reversible unfolding and refolding of protein domains to trigger deformation and recovery of the programed shape.…”

Section: Discussionmentioning

confidence: 99%

Chemical unfolding of protein domains induces shape change in programmed protein hydrogels

Khoury

Popa

2019

Nat Commun

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Programmable behavior combined with tailored stiffness and tunable biomechanical response are key requirements for developing successful materials. However, these properties are still an elusive goal for protein-based biomaterials. Here, we use protein-polymer interactions to manipulate the stiffness of protein-based hydrogels made from bovine serum albumin (BSA) by using polyelectrolytes such as polyethyleneimine (PEI) and poly-L-lysine (PLL) at various concentrations. This approach confers protein-hydrogels with tunable wide-range stiffness, from ~10–64 kPa, without affecting the protein mechanics and nanostructure. We use the 6-fold increase in stiffness induced by PEI to program BSA hydrogels in various shapes. By utilizing the characteristic protein unfolding we can induce reversible shape-memory behavior of these composite materials using chemical denaturing solutions. The approach demonstrated here, based on protein engineering and polymer reinforcing, may enable the development and investigation of smart biomaterials and extend protein hydrogel capabilities beyond their conventional applications.

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Section: Discussionmentioning

confidence: 99%

Chemical unfolding of protein domains induces shape change in programmed protein hydrogels

Khoury

Popa

2019

Nat Commun

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“…Other classes of soft‐robotic hydrogel structures include a variety of folding and unfolding structures and soft tethered or untethered gripping devices. As an example, Zhang et al used CNT‐hydrogel composites to thermally or optically swell and de‐swell and guide a flower to bloom or to reversibly fold and close a cube ( Figure a) . Yuk et al described osmotically or pneumatically actuated and optically and sonically camouflaged grippers.…”

Section: Applicationsmentioning

confidence: 99%

Transformer Hydrogels: A Review

Erol

Pantula

Liu

et al. 2019

Adv Materials Technologies

221

210

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Hydrogels, which are hydrophilic soft porous networks, are an important class of materials of broad relevance to bioanalytical chemistry, soft‐robotics, drug delivery, and regenerative medicine. Transformer hydrogels are micro‐ and mesostructured hydrogels that display a dramatic transformation of shape, form, or dimension with associated changes in function, due to engineered local variations such as in swelling or stiffness, in response to external controls or environmental stimuli. This review describes principles that can be utilized to fabricate transformer hydrogels such as by layering, patterning, or generating anisotropy, and gradients. Transformer hydrogels are classified based on their responsivity to different stimuli such as temperature, electromagnetic fields, chemicals, and biomolecules. A survey of the current research progress suggests applications of transformer hydrogels in biomimetics, soft robotics, microfluidics, tissue engineering, drug delivery, surgery, and biomedical engineering.

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“…Currently, many promising actuating materials, that can potentially trigger 2D‐to‐3D shape transformations, are available, such as dielectric elastomers, shape‐memory polymers, polymer composites, and hydrogels, which can be driven by electricity, heat, light, magnetism, solvent, humidity, and/or multi‐stimuli. [ 25–39 ] For example, compressive bulking guided, on‐demand 3D assembly has been recently achieved by using dielectric elastomers [ 38 ] and shape memory polymers [ 39 ] as the assembly substrates. However, these two strategies have some limitations in terms of high operation voltages (thousands of volts) and poor reversibility and cyclability, respectively.…”

Section: Figurementioning

confidence: 99%

Laser‐Induced Graphene for Electrothermally Controlled, Mechanically Guided, 3D Assembly and Human–Soft Actuators Interaction

et al. 2020

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Strategically designed, well-defined 3D architectures could offer great opportunities, that are unavailable in their 2D counterparts, for a broad spectrum of applications, such as microelectronics, bioelectronics, photonics and optoelectronics, micro-electromechanical systems, metamaterials, energy storage and harvesting, soft robotics, and many others. Existing manufacturing techniques of 3D structures mainly include 3D printing, templated growth, fluidic self-assembly, and mechanically guided 3D assembly. Among these methods, the mechanically guided 3D assembly has recently attracted broad attention in the scientific community. The process starts from the planar fabrication of patterned 2D precursor structures, followed by the 2D-to-3D shape transformation via controlled rolling, folding, curving, and/ or buckling. [4] This process is naturally compatible with existing advanced planar fabrication technologies (e.g., lithographic and laser-processing techniques). Consequently, micro/nanoscale structures, sensors and/or other functional components Mechanically guided, 3D assembly has attracted broad interests, owing to its compatibility with planar fabrication techniques and applicability to a diversity of geometries and length scales. Its further development requires the capability of on-demand reversible shape reconfigurations, desirable for many emerging applications (e.g., responsive metamaterials, soft robotics). Here, the design, fabrication, and modeling of soft electrothermal actuators based on laser-induced graphene (LIG) are reported and their applications in mechanically guided 3D assembly and human-soft actuators interaction are explored. Over 20 complex 3D architectures are fabricated, including reconfigurable structures that can reshape among three distinct geometries. Also, the structures capable of maintaining 3D shapes at room temperature without the need for any actuation are realized by fabricating LIG actuators at an elevated temperature. Finite element analysis can quantitatively capture key aspects that govern electrothermally controlled shape transformations, thereby providing a reliable tool for rapid design optimization. Furthermore, their applications are explored in human-soft actuators interaction, including elastic metamaterials with human gesture-controlled bandgap behaviors and soft robotic fingers which can measure electrocardiogram from humans in an on-demand fashion. Other demonstrations include artificial muscles, which can lift masses that are about 110 times of their weights and biomimetic frog tongues which can prey insects.

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Protein‐Based Hydrogels that Actuate Self‐Folding Systems

Cited by 18 publications

References 57 publications

Chemical unfolding of protein domains induces shape change in programmed protein hydrogels

Chemical unfolding of protein domains induces shape change in programmed protein hydrogels

Transformer Hydrogels: A Review

Laser‐Induced Graphene for Electrothermally Controlled, Mechanically Guided, 3D Assembly and Human–Soft Actuators Interaction

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