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DDC: 500 × Type: Text × Version: publishedVersion × Publisher: Washington, DC [u.a.] : Assoc. × WGL Institute: IPF ×

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    Molecular structure of bottlebrush polymers in melts
    (Washington, DC [u.a.] : Assoc., 2016) Paturej, Jarosław; Sheiko, Sergei S.; Panyukov, Sergey; Rubinstein, Michael
    Bottlebrushes are fascinating macromolecules that display an intriguing combination of molecular and particulate features having vital implications in both living and synthetic systems, such as cartilage and ultrasoft elastomers. However, the progress in practical applications is impeded by the lack of knowledge about the hierarchic organization of both individual bottlebrushes and their assemblies. We delineate fundamental correlations between molecular architecture, mesoscopic conformation, and macroscopic properties of polymer melts. Numerical simulations corroborate theoretical predictions for the effect of grafting density and side-chain length on the dimensions and rigidity of bottlebrushes, which effectively behave as a melt of flexible filaments. These findings provide quantitative guidelines for the design of novel materials that allow architectural tuning of their properties in a broad range without changing chemical composition.
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    A thrombin-triggered self-regulating anticoagulant strategy combined with anti-inflammatory capacity for blood-contacting implants
    (Washington, DC [u.a.] : Assoc., 2022) Wang, Yanan; Wu, Haoshuang; Zhou, Zhongyi; Maitz, Manfred F.; Liu, Kunpeng; Zhang, Bo; Yang, Li; Luo, Rifang; Wang, Yunbing
    Interrelated coagulation and inflammation are impediments to endothelialization, a prerequisite for the longterm function of cardiovascular materials. Here, we proposed a self-regulating anticoagulant coating strategy combined with anti-inflammatory capacity, which consisted of thrombin-responsive nanogels with anticoagulant and anti-inflammatory components. As an anticoagulant, rivaroxaban was encapsulated in nanogels cross-linked by thrombin-cleavable peptide and released upon the trigger of environmental thrombin, blocking the further coagulation cascade. The superoxide dismutase mimetic Tempol imparted the antioxidant property. Polyphenol epigallocatechin gallate (EGCG), in addition to its anti-inflammatory function in synergy with Tempol, also acted as a weak cross-linker to stabilize the coating. The effectiveness and versatility of this coating were validated using two typical cardiovascular devices as models, biological valves and vascular stents. It was demonstrated that the coating worked as a precise strategy to resist coagulation and inflammation, escorted reendothelialization on the cardiovascular devices, and provided a new perspective for designing endothelium-like functional coatings.
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    Self-organized stress patterns drive state transitions in actin cortices
    (Washington, DC [u.a.] : Assoc., 2018) Tan, Tzer Han; Malik-Garbi, Maya; Abu-Shah, Enas; Li, Junang; Sharma, Abhinav; MacKintosh, Fred C.; Keren, Kinneret; Schmidt, Christoph F.; Fakhri, Nikta
    Biological functions rely on ordered structures and intricately controlled collective dynamics. This order in living systems is typically established and sustained by continuous dissipation of energy. The emergence of collective patterns of motion is unique to nonequilibrium systems and is a manifestation of dynamic steady states. Mechanical resilience of animal cells is largely controlled by the actomyosin cortex. The cortex provides stability but is, at the same time, highly adaptable due to rapid turnover of its components. Dynamic functions involve regulated transitions between different steady states of the cortex. We find that model actomyosin cortices, constructed to maintain turnover, self-organize into distinct nonequilibrium steady states when we vary cross-link density. The feedback between actin network structure and organization of stress-generating myosin motors defines the symmetries of the dynamic steady states. A marginally cross-linked state displays divergence-free long-range flow patterns. Higher cross-link density causes structural symmetry breaking, resulting in a stationary converging flow pattern. We track the flow patterns in the model actomyosin cortices using fluorescent single-walled carbon nanotubes as novel probes. The self-organization of stress patterns we have observed in a model system can have direct implications for biological functions.