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DDC: 500 × Publisher: Weinheim : Wiley-VCH × WGL Institute: INM ×

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    Regulating Bacterial Behavior within Hydrogels of Tunable Viscoelasticity
    (Weinheim : Wiley-VCH, 2022) Bhusari, Shardul; Sankaran, Shrikrishnan; del Campo, Aránzazu
    Engineered living materials (ELMs) are a new class of materials in which living organism incorporated into diffusive matrices uptake a fundamental role in material's composition and function. Understanding how the spatial confinement in 3D can regulate the behavior of the embedded cells is crucial to design and predict ELM's function, minimize their environmental impact and facilitate their translation into applied materials. This study investigates the growth and metabolic activity of bacteria within an associative hydrogel network (Pluronic-based) with mechanical properties that can be tuned by introducing a variable degree of acrylate crosslinks. Individual bacteria distributed in the hydrogel matrix at low density form functional colonies whose size is controlled by the extent of permanent crosslinks. With increasing stiffness and elastic response to deformation of the matrix, a decrease in colony volumes and an increase in their sphericity are observed. Protein production follows a different pattern with higher production yields occurring in networks with intermediate permanent crosslinking degrees. These results demonstrate that matrix design can be used to control and regulate the composition and function of ELMs containing microorganisms. Interestingly, design parameters for matrices to regulate bacteria behavior show similarities to those elucidated for 3D culture of mammalian cells.
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    Graphene Acid for Lithium‐Ion Batteries—Carboxylation Boosts Storage Capacity in Graphene
    (Weinheim : Wiley-VCH, 2021) Obraztsov, Ievgen; Bakandritsos, Aristides; Šedajová, Veronika; Langer, Rostislav; Jakubec, Petr; Zoppellaro, Giorgio; Pykal, Martin; Presser, Volker; Otyepka, Michal; Zbořil, Radek
    Environmentally sustainable, low-cost, flexible, and lightweight energy storage technologies require advancement in materials design in order to obtain more efficient organic metal-ion batteries. Synthetically tailored organic molecules, which react reversibly with lithium, may address the need for cost-effective and eco-friendly anodes used for organic/lithium battery technologies. Among them, carboxylic group-bearing molecules act as high-energy content anodes. Although organic molecules offer rich chemistry, allowing a high content of carboxyl groups to be installed on aromatic rings, they suffer from low conductivity and leakage to the electrolytes, which restricts their actual capacity, the charging/discharging rate, and eventually their application potential. Here, a densely carboxylated but conducting graphene derivative (graphene acid (GA)) is designed to circumvent these critical limitations, enabling effective operation without compromising the mechanical or chemical stability of the electrode. Experiments including operando Raman measurements and theoretical calculations reveal the excellent charge transport, redox activity, and lithium intercalation properties of the GA anode at the single-layer level, outperforming all reported organic anodes, including commercial monolayer graphene and graphene nanoplatelets. The practical capacity and rate capability of 800 mAh g−1 at 0.05 A g−1 and 174 mAh g−1 at 2.0 A g−1 demonstrate the true potential of GA anodes in advanced lithium-ion batteries.