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    Digitally Fabricated and Naturally Augmented In Vitro Tissues
    (Weinheim : Wiley-VCH, 2020) Duarte Campos, Daniela F.; De Laporte, Laura
    Human in vitro tissues are extracorporeal 3D cultures of human cells embedded in biomaterials, commonly hydrogels, which recapitulate the heterogeneous, multiscale, and architectural environment of the human body. Contemporary strategies used in 3D tissue and organ engineering integrate the use of automated digital manufacturing methods, such as 3D printing, bioprinting, and biofabrication. Human tissues and organs, and their intra- and interphysiological interplay, are particularly intricate. For this reason, attentiveness is rising to intersect materials science, medicine, and biology with arts and informatics. This report presents advances in computational modeling of bioink polymerization and its compatibility with bioprinting, the use of digital design and fabrication in the development of fluidic culture devices, and the employment of generative algorithms for modeling the natural and biological augmentation of in vitro tissues. As a future direction, the use of serially linked in vitro tissues as human body-mimicking systems and their application in drug pharmacokinetics and metabolism, disease modeling, and diagnostics are discussed. © 2020 The Authors. Advanced Healthcare Materials published by Wiley-VCH GmbH
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    Impact of Reactive Amphiphilic Copolymers on Mechanical Properties and Cell Responses of Fibrin-Based Hydrogels
    (Weinheim : Wiley-VCH, 2020) Al Enezy-Ulbrich, Miriam Aischa; Malyaran, Hanna; de Lange, Robert Dirk; Labude, Norina; Plum, René; Rütten, Stephan; Terefenko, Nicole; Wein, Svenja; Neuss, Sabine; Pich, Andrij
    Mechanical properties of hydrogels can be modified by the variation of structure and concentration of reactive building blocks. One promising biological source for the synthesis of biocompatible hydrogels is fibrinogen. Fibrinogen is a glycoprotein in blood, which can be transformed enzymatically to fibrin playing an important role in wound healing and clot formation. In the present work, it is demonstrated that hybrid hydrogels with their improved mechanical properties, tunable internal structure, and enhanced resistance to degradation can be synthesized by a combination of fibrinogen and reactive amphiphilic copolymers. Water-soluble amphiphilic copolymers with tunable molecular weight and controlled amounts of reactive epoxy side groups are used as reactive crosslinkers to reinforce fibrin hydrogels. In the present work, copolymers that can influence the mechanical properties of fibrin-based hydrogels are used. The reactive copolymers increase the storage modulus of the hydrogels from 600 Pa to 30 kPa. The thickness of fibrin fibers is regulated by the copolymer concentration. It could be demonstrated that the fibrin-based hydrogels are biocompatible and support cell proliferation. Their degradation rate is considerably slower than that of native fibrin gels. In conclusion, fibrin-based hydrogels with tunable elasticity and fiber thickness useful to direct cell responses like proliferation and differentiation are produced. © 2020 The Authors. Published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
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    4D Printing of a Light-Driven Soft Actuator with Programmed Printing Density
    (Washington, DC : ACS Publications, 2020) Nishiguchi, Akihiro; Zhang, Hang; Schweizerhof, Sjören; Schulte, Marie Friederike; Mourran, Ahmed; Möller, Martin
    There is a growing interest in the concept of four-dimensional (4D) printing that combines a three-dimensional (3D) manufacturing process with dynamic modulation for bioinspired soft materials exhibiting more complex functionality. However, conventional approaches have drawbacks of low resolution, control of internal micro/nanostructure, and creation of fast, complex actuation due to a lack of high-resolution fabrication technology and suitable photoresist for soft materials. Here, we report an approach of 4D printing that develops a bioinspired soft actuator with a defined 3D geometry and programmed printing density. Multiphoton lithography (MPL) allows for controlling printing density in gels at pixel-by-pixel with a resolution of a few hundreds of nanometers, which tune swelling behaviors of gels in response to external stimuli. We printed a 3D soft actuator composed of thermoresponsive poly(N-isopropylacrylamide) (PNIPAm) and gold nanorods (AuNRs). To improve the resolution of printing, we synthesized a functional, thermoresponsive macrocrosslinker. Through plasmonic heating by AuNRs, nanocomposite-based soft actuators undergo nonequilibrium, programmed, and fast actuation. Light-mediated manufacture and manipulation (MPL and photothermal effect) offer the feasibility of 4D printing toward adaptive bioinspired soft materials. Copyright © 2020 American Chemical Society.
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    Pros and Cons : Supramolecular or Macromolecular : What Is Best for Functional Hydrogels with Advanced Properties?
    (Weinheim : Wiley-VCH, 2020) Eelkema, Rienk; Pich, Andrij
    Hydrogels are fascinating soft materials with unique properties. Many biological systems are based on hydrogel-like structures, underlining their versatility and relevance. The properties of hydrogels strongly depend on the structure of the building blocks they are composed of, as well as the nature of interactions between them in the network structure. Herein, gel networks made by supramolecular interactions are compared to covalent macromolecular networks, drawing conclusions about their performance and application as responsive materials. © 2020 The Authors. Published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim