Complex Fluids Research Group, College of Engineering, Swansea University, SA1 8EN.
Soft Matter. 2018 Jan 24;14(4):574-580. doi: 10.1039/c7sm01933e.
The ability to control the mechanical properties of cell culture environments is known to influence cell morphology, motility, invasion and differentiation. The present work shows that it is possible to control the mechanical properties of collagen gels by manipulating gelation conditions near the sol gel transition. This manipulation is accomplished by performing gelation in two stages at different temperatures. The mechanical properties of the gel are found to be strongly dependent on the duration and temperature of the first stage. In the second stage the system is quickly depleted of free collagen which self assembles into a highly branched network characteristic of gelation at the higher temperature (37 °C). An important aspect of the present work is the use of advanced rheometric techniques to assess the transition point between viscoelastic liquid and viscoelastic solid behaviour which occurs upon establishment of a sample spanning network at the gel point. The gel time at the stage I temperature is found to indicate the minimum time that the gelling collagen sample must spend under stage I conditions before the two stage gelation procedure generates an enhancement of mechanical properties. Further, the Fractional Maxwell Model is found to provide an excellent description of the time-dependent mechanical properties of the mature collagen gels.
众所周知，控制细胞培养环境的机械性能可以影响细胞形态、迁移、侵袭和分化。本工作表明，通过在溶胶-凝胶转变附近改变凝胶化条件，可以控制胶原凝胶的机械性能。这种操作是通过在不同温度下分两个阶段进行凝胶化来完成的。发现凝胶的机械性能强烈依赖于第一阶段的持续时间和温度。在第二阶段，系统中很快耗尽了游离胶原蛋白，其自组装成高度分支的网络，这是在较高温度（37°C）下凝胶化的特征。本工作的一个重要方面是使用先进的流变技术来评估在凝胶点建立跨越样品的网络时发生的粘弹性液体和粘弹性固体行为之间的转变点。在第一阶段温度下的凝胶时间被发现表明，在两阶段凝胶化程序产生机械性能增强之前，凝胶化胶原样品必须在第一阶段条件下花费的最小时间。此外，分数 Maxwell 模型被发现为成熟胶原凝胶的时变机械性能提供了极好的描述。
