生物聚合物交联网络的力学响应  

Mechanical Responses of Crosslinked Biopolymer Networks

作　　者：程传亮 龚博[1] 钱劲[1,2] 

机构地区：[1]浙江大学航空航天学院软物质科学研究中心,杭州310027 [2]浙江省软体机器人与智能器件研究重点实验室(浙江大学),杭州310027

出　　处：《应用数学和力学》2016年第5期441-458,共18页Applied Mathematics and Mechanics

基　　金：国家自然科学基金(11321202);浙江省自然科学基金(LR16A020001)~~

摘　　要：生物聚合物交联网络(crosslinked biopolymer networks)是由肌动蛋白微丝等生物纤维相互交联形成的复杂网络结构,它广泛存在于细胞骨架和生物凝胶等系统中,对维持细胞完整性、使细胞具有主动变形和抵抗被动变形能力起着不可或缺的作用,其力学响应及工作机理对细胞工程、组织工程的发展非常重要.生物聚合物交联网络中交联蛋白的结合能量通常较低,其解离和重连过程容易受到网络结构变形和环境热涨落等因素的影响.实验中发现生物聚合物交联网络在小变形时刚度较低,但随着变形的增加,网络整体刚度会呈现数量级的增加,如果变形继续增加并超过一定阈值,网络刚度将急剧下降,这种应变硬化到软化的现象引起了研究者的广泛关注.已有理论模型和数值模拟发现,生物聚合物交联网络的硬化主要来源于纤维变形模式从弯曲到拉伸的转化,而软化则是由于网络中交联蛋白解离导致结构弱化和应力松弛.从生物聚合物交联网络的微观组成和结构出发,综述了生物聚合物纤维的力学模型、交联蛋白的力学属性和交联方式、交联网络的主要构型以及测量网络力学响应的实验方法,重点讨论了理论建模、有限元模拟、分子动力学等方法在研究生物聚合物交联网络非线性力学行为的进展,旨在为具有不同专业背景的研究者了解并开展生物聚合物交联网络力学响应的相关研究提供参考,也有助于机理化、定量化地理解细胞骨架中蕴含的结构-功能关系.Crosslinked biopolymer networks are composed of filaments randomly distributed and crosslinked by specific binders, and are widespread in cytoskeletons of cells, biological gels and other natural materials, The binding energy of typical crosslinks in such biopolymer networks is relatively low and close to thermal energy, so that the binding status of the interac- tion is strongly influenced by the deformation of networks and thermal excitations from the en- vironment. Experiments on different types of crosslinked biopolymer networks have demonstra- ted that these networks exhibit a linear response with low modulus in small deformation, and can be stiffened by more than two orders of magnitude in large strain. However, the network stiffness decreases dramatically when the applied strain exceeds a threshold value. This phenomenon is known as the transition from strain hardening to softening, and draws great attention from many researchers. Theoretical and numerical studies have indicated that such strain hardening is mainly caused by a transition from bending-dominated filament deformation in small strain to stretching-dominated response in large strain, and the strain softening is due to the microscopic unbinding of crosslinks, leading to weakened networks. This paper overviews the key components and representative architectures of crosslinked biopolymer networks, stretching behaviors of biopolymers, types and properties of crosslinks, and experimental methods used to measure the mechanical responses of network structures, with an emphasis on the theoretical, finite element and molecular dynamics models that pave the way to the under-standing of the structure-function relations in crosslinked biopolymer networks.

关 键 词：生物聚合物交联网络 力学响应 聚合物纤维 交联 硬化-软化 非线性 

分 类 号：O34[理学—固体力学] O39[理学—力学]