弹性

Abstract(#br)In nanoindentation tests for soft polymers, the elastic modulus estimated from the Hertz model varies with applied force, implying the effect of adhesion work needs to be considered in contact theory. In this article, a hybrid method of combining the Hertz model and the Johnson–Kendall–Roberts (JKR) model is presented, to analytically explain the descending phenomenon of the modulus estimation by considering adhesive effects.

Abstract(#br)Matrix elasticity guides differentiation of mesenchymal stem cells (MSCs) but it is unclear if these effects are only transient – while the cells reside on the substrate – or if they reflect persistent lineage commitment. In this study, MSCs were continuously culture-expanded in parallel either on tissue culture plastic (TCP) or on polydimethylsiloxane (PDMS) gels of different elasticity to compare impact on replicative senescence, in vitro differentiation, gene expression, and DNA methylation (DNAm) profiles.

Abstract(#br)In cardiac tissue engineering (TE), in vitro models are essential for the study of healthy and pathological heart tissues in order to understand the underpinning mechanisms. In this scenario, scaffolds are platforms that can realistically mimic the natural architecture of the heart, and they add biorealism to in vitro models. This paper reports a novel and robust technique to fabricate cardiovascular-mimetic scaffolds based on Parylene C and Polydimethylsiloxane (PDMS). Parylene C is employed as a mask material for inducing hybrid and non-hybrid micropatterns to the PDMS layer.

磁性弹性体( MEs )通过磁力机械耦合作用响应一个外加磁场，其中MEs的力学性能随磁场强度的变化而变化。这些现象在均匀磁场下由于简单而得到了广泛的研究。本工作考察了磁场梯度对MEs力学性能和响应的影响。MEs是将羰基铁微粒( CI )嵌入到聚二甲基硅氧烷( PDMS )基体中制成的，随后被渲染成多孔状。以CI / PDMS质量比分别为0.2、0.6、1.0和1.4的4种不同的样品为研究对象，考察了CI浓度的影响。提出了进一步了解磁场梯度与材料响应之间相互作用的分析方法。随后用不同磁场存在下的压缩试验结果验证了所提理论。所提出的理论框架和实验方法可用于今后MEs的设计改进。

Microglia——大脑的初级免疫细胞———在脑病理上表现出一个由促炎和抗炎作用紧密调节的级联反应，要么促进再生，要么促进神经退化。因此，小胶质细胞的治疗成为神经科学研究的一个潜在的治疗理念。最近的研究表明，除了受趋化因子和细胞因子的影响外，大脑中的各种细胞实体对其微环境的力学性质也有相应的反应。例如，我们最近报告了弹性对神经干细胞的相当大的影响，关于安静和分化潜能。然而，弹性对小胶质细胞的影响还有待探讨。在微环境的弹性影响小胶质细胞关键特性和功能的假设下，我们建立了在聚二甲基硅氧烷( PDMS )弹性体为主的细胞培养体系中生长的原代大鼠小胶质细胞体外模型。这样，我们模拟了大脑的生理弹性范围，并将其与超生理僵硬的PDMS对照进行了比较。我们评估了小胶质细胞在“静息”状态下的功能参数，以及在脂多糖( LPS )或白介素-4 ( IL-4 )极化为促炎表型( M1 )或抗炎表型( M2 )时的功能参数。在软基上，小胶质细胞的活力没有受到损害，但我们发现在模拟大脑的软基弹性(相对于PDMS对照)上，小胶质细胞的增殖增加了两倍多。此外，软底物促进小胶质细胞活化标志波形蛋白的表达。而且，M2标记的CD206与胰岛素样生长因子-1 ( IGF-1 )分泌增加平行上调。CD206的上调通过阻断牵张依赖性氯通道而被取消。