Synthetic homeostatic materials with chemo-mechano-chemical self-regulation
Synthetic homeostatic materials with chemo-mechano-chemical self-regulation
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DOI：
10.1038/nature11223
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发表时间：
2012-07-12
期刊：
影响因子：
64.8
通讯作者：
Aizenberg, Joanna
中科院分区：
文献类型：
--
作者：
He, Ximin;Aizenberg, Michael;Aizenberg, Joanna
生物体具有独特的动态平衡能力，通过化学和机械能的相互转换和在许多长度尺度上分级组织的自我调节反馈循环来维持对当地环境的严格控制(1-7)。相反，大多数合成材料由于其有限的单向化学机械(7-12)或机械化学(13，14)模式而不能持续自我监测和自我调节行为。将动态平衡的概念应用于自主材料的设计(15)将在从有助于稳定身体功能的医疗植入物到调节能源使用的“智能”材料等领域产生重大影响(2，16，17)。在这里，我们提出了一种通用的策略，用于创建自我调节、自我供电、能够在纳米或微米尺度上精确定制化学-机械化学反馈回路的自稳材料。我们设计了一种双层体系，它具有水凝胶支撑的、带有催化剂的微结构，这些微结构与含有反应物的‘营养’层分开。凝胶对刺激的响应重新配置诱导微结构进入和离开营养层的可逆驱动，并作为化学反应的高精度的开/关开关。我们应用这种设计来触发有机、无机和生化反应，这些反应经历了与微结构的运动和驱动外部化学刺激同步的可逆、可重复的循环。通过利用营养层中的各种放热催化反应和温度响应性凝胶的机械作用之间的连续反馈循环，我们然后创建了示范性的自主、自我维持的动态平衡系统，将用户定义的参数-温度-保持在较小的范围内。实验结果得到了计算模型的验证，该模型定性地捕捉了自我调节行为的基本特征，并为平衡功能的优化提供了额外的标准，随后得到了实验证实。这种设计是高度可定制的，因为有广泛的化学选择，可调的力学和它的物理简单性，并可能导致在以化学-机械-化学转导为核心的自治系统中的各种应用。
Living organisms have unique homeostatic abilities, maintaining tight control of their local environment through interconversions of chemical and mechanical energy and self-regulating feedback loops organized hierarchically across many length scales(1-7). In contrast, most synthetic materials are incapable of continuous self-monitoring and self-regulating behaviour owing to their limited single-directional chemomechanical(7-12) or mechanochemical(13,14) modes. Applying the concept of homeostasis to the design of autonomous materials(15) would have substantial impacts in areas ranging from medical implants that help stabilize bodily functions to 'smart' materials that regulate energy usage(2,16,17). Here we present a versatile strategy for creating self-regulating, self-powered, homeostatic materials capable of precisely tailored chemo-mechanochemical feedback loops on the nano- or microscale. We design a bilayer system with hydrogel-supported, catalyst-bearing microstructures, which are separated from a reactant-containing 'nutrient' layer. Reconfiguration of the gel in response to a stimulus induces the reversible actuation of the microstructures into and out of the nutrient layer, and serves as a highly precise 'on/off' switch for chemical reactions. We apply this design to trigger organic, inorganic and biochemical reactions that undergo reversible, repeatable cycles synchronized with the motion of the microstructures and the driving external chemical stimulus. By exploiting a continuous feedback loop between various exothermic catalytic reactions in the nutrient layer and the mechanical action of the temperature-responsive gel, we then create exemplary autonomous, self-sustained homeostatic systems that maintain a user-defined parameter-temperature-in a narrow range. The experimental results are validated using computational modelling that qualitatively captures the essential features of the self-regulating behaviour and provides additional criteria for the optimization of the homeostatic function, subsequently confirmed experimentally. This design is highly customizable owing to the broad choice of chemistries, tunable mechanics and its physical simplicity, and may lead to a variety of applications in autonomous systems with chemo-mechano-chemical transduction at their core.