Squid-Inspired Tandem Repeat Proteins: Functional Fibers and Films

Production of repetitive polypeptides that comprise one or more tandem copies of a single unit with distinct amorphous and ordered regions have been an interest for the last couple of decades. Their molecular structure provides a rich architecture that can micro-phase-separate to form periodic nanostructures (e.g., lamellar and cylindrical repeating phases) with enhanced physicochemical properties via directed or natural evolution that often exceed those of conventional synthetic polymers. Here, we review programmable design, structure, and properties of functional fibers and films from squid-inspired tandem repeat proteins, with applications in soft photonics and advanced textiles among others

Zwitterionic 3D- Printed Non- Immunogenic Stealth Microrobots

Microrobots offer transformative solutions for non- invasive medical interventions due to their small size and untethered operation inside the human body. However, they must face the immune system as a natural protection mechanism against foreign threats. Here, non- immunogenic stealth zwitterionic microrobots that avoid recognition from immune cells are introduced. Fully zwitterionic photoresists are developed for two- photon polymerization 3D microprinting of hydrogel microrobots with ample functionalization: tunable mechanical properties, anti- biofouling and non- immunogenic properties, functionalization for magnetic actuation, encapsulation of biomolecules, and surface functionalization for drug delivery. Stealth microrobots avoid detection by macrophage cells of the innate immune system after exhaustive inspection (>90 hours), which has not been achieved in any microrobotic platform to date. These versatile zwitterionic materials eliminate a major roadblock in the development of biocompatible microrobots, and will serve as a toolbox of non- immunogenic materials for medical microrobot and other device technologies for bioengineering and biomedical applications.Zwitterionic stealth microrobots avoid detection and capture by immune cells. Zwitterionic microrobots with anti- biofouling, stealth, and non- immunogenic properties are 3D- printed via two- photon- polymerization, and are functionalized for magnetic actuation, encapsulation of biomolecules, and drug delivery. The microrobots remain undetected by macrophages and other immune cells for at least 90 hours, overcoming a major roadblock in medical microrobotics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/163416/3/adma202003013-sup-0001-SuppMat.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/163416/2/adma202003013.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/163416/1/adma202003013_am.pd

High shear rate propulsion of acoustic microrobots in complex biological fluids

Untethered microrobots offer a great promise for localized targeted therapy in hard-to-access spaces in our body. Despite recent advancements, most microrobot propulsion capabilities have been limited to homogenous Newtonian fluids. However, the biological fluids present in our body are heterogeneous and have shear rate-dependent rheological properties, which limit the propulsion of microrobots using conventional designs and actuation methods. We propose an acoustically powered microrobotic system, consisting of a three-dimensionally printed 30-micrometer-diameter hollow body with an oscillatory microbubble, to generate high shear rate fluidic flow for propulsion in complex biofluids. The acoustically induced microstreaming flow leads to distinct surface-slipping and puller-type propulsion modes in Newtonian and non-Newtonian fluids, respectively. We demonstrate efficient propulsion of the microrobots in diverse biological fluids, including in vitro navigation through mucus layers on biologically relevant three-dimensional surfaces. The microrobot design and high shear rate propulsion mechanism discussed herein could open new possibilities to deploy microrobots in complex biofluids toward minimally invasive targeted therapy.ISSN:2375-254

Liquid‐Crystal‐Elastomer‐Actuated Reconfigurable Microscale Kirigami Metastructures

Programmable actuation of metastructures with predesigned geometrical configurations has recently drawn significant attention in many applications, such as smart structures, medical devices, soft robotics, prosthetics, and wearable devices. Despite remarkable progress in this field, achieving wireless miniaturized reconfigurable metastructures remains a challenge due to the difficult nature of the fabrication and actuation processes at the micrometer scale. Herein, microscale thermo-responsive reconfigurable metasurfaces using stimuli-responsive liquid crystal elastomers (LCEs) is fabricated as an artificial muscle for reconfiguring the 2D microscale kirigami structures. Such structures are fabricated via two-photon polymerization with sub-micrometer precision. Through rationally designed experiments guided by simulations, the optimal formulation of the LCE artificial muscle is explored and the relationship between shape transformation behaviors and geometrical parameters of the kirigami structures is build. As a proof of concept demonstration, the constructs for temperature-dependent switching and information encryption is applied. Such reconfigurable kirigami metastructures have significant potential for boosting the fundamental small-scale metastructure research and the design and fabrication of wireless functional devices, wearables, and soft robots at the microscale as well.ISSN:0935-9648ISSN:1521-409

Liquid- Crystal- Elastomer- Actuated Reconfigurable Microscale Kirigami Metastructures

Programmable actuation of metastructures with predesigned geometrical configurations has recently drawn significant attention in many applications, such as smart structures, medical devices, soft robotics, prosthetics, and wearable devices. Despite remarkable progress in this field, achieving wireless miniaturized reconfigurable metastructures remains a challenge due to the difficult nature of the fabrication and actuation processes at the micrometer scale. Herein, microscale thermo- responsive reconfigurable metasurfaces using stimuli- responsive liquid crystal elastomers (LCEs) is fabricated as an artificial muscle for reconfiguring the 2D microscale kirigami structures. Such structures are fabricated via two- photon polymerization with sub- micrometer precision. Through rationally designed experiments guided by simulations, the optimal formulation of the LCE artificial muscle is explored and the relationship between shape transformation behaviors and geometrical parameters of the kirigami structures is build. As a proof of concept demonstration, the constructs for temperature- dependent switching and information encryption is applied. Such reconfigurable kirigami metastructures have significant potential for boosting the fundamental small- scale metastructure research and the design and fabrication of wireless functional devices, wearables, and soft robots at the microscale as well.Programmable and reconfigurable metasurfaces at the microscale are achieved by using uniaxially aligned liquid crystal elastomer film as artificial muscle to thermally actuate kirigami microstructures 3D- printed via the two- photon polymerization technique. This strategy paves the way to a host of potential applications, such as tunable phononic/photonic crystals, optoelectronics, biomedical devices, camouflage, microelectromechanical systems, and soft microrobots.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/168316/1/adma202008605-sup-0001-SuppMat.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/168316/2/adma202008605.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/168316/3/adma202008605_am.pd

Kirigami Metastructures: Liquid- Crystal- Elastomer- Actuated Reconfigurable Microscale Kirigami Metastructures (Adv. Mater. 25/2021)

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/168290/1/adma202170195.pd

Pressure sensitive adhesion of an elastomeric protein complex extracted from squid ring teeth

The pressure sensitive adhesion characteristic of a protein complex extracted from squid ring teeth (SRT), which exhibits an unusual and reversible transition from a solid to a melt, is studied. The native SRT is an elastomeric protein complex that has standard amino acids, and it does not function as adhesives in nature. The SRT can be thermally shaped into any 3D geometry (e.g., thin films, ribbons, colloids), and it has a glass transition temperature of 32 °C in water. Underwater adhesion strength of the protein film is approximately 1.5–2.5 MPa. The thermoplastic protein film could potentially be used in an array of fields, including dental resins, bandages for wound healing, and surgical sutures in the body

Microrobots: Zwitterionic 3D- Printed Non- Immunogenic Stealth Microrobots (Adv. Mater. 42/2020)

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/163415/1/adma202070312.pd

Segmented molecular design of self-healing proteinaceous materials

In article: OpenHierarchical assembly of self-healing adhesive proteins creates strong and robust structural and interfacial materials, but understanding of the molecular design and structure-property relationships of structural proteins remains unclear. Elucidating this relationship would allow rational design of next generation genetically engineered self-healing structural proteins. Here we report a general self-healing and -assembly strategy based on a multiphase recombinant protein based material. Segmented structure of the protein shows soft glycine- and tyrosine-rich segments with self-healing capability and hard beta-sheet segments. The soft segments are strongly plasticized by water, lowering the self-healing temperature close to body temperature. The hard segments self-assemble into nanoconfined domains to reinforce the material. The healing strength scales sublinearly with contact time, which associates with diffusion and wetting of autohesion. The finding suggests that recombinant structural proteins from heterologous expression have potential as strong and repairable engineering materials.Peer reviewe