Jones Christopher Allen Rucksack, Liang Long, Lin Daniel, Jiao Yang, Sun Bo
Department of Physics, Oregon State University, Corvallis, OR 97331, USA.
Soft Matter. 2014 Nov 28;10(44):8855-63. doi: 10.1039/c4sm01772b.
Type I collagen abounds in mammalian extracellular matrix (ECM) and is crucial to many biophysical processes. While previous studies have mostly focused on bulk averaged properties, here we provide a comprehensive and quantitative spatial-temporal characterization of the microstructure of type I collagen-based ECM as the gelation temperature varies. The structural characteristics including the density and nematic correlation functions are obtained by analyzing confocal images of collagen gels prepared at a wide range of gelation temperatures (from 16 °C to 36 °C). As temperature increases, the gel microstructure varies from a "bundled" network with strong orientational correlation between the fibers to an isotropic homogeneous network with no significant orientational correlation, as manifested by the decaying of length scales in the correlation functions. We develop a kinetic Monte-Carlo collagen growth model to better understand how ECM microstructure depends on various environmental or kinetic factors. We show that the nucleation rate, growth rate, and an effective hydrodynamic alignment of collagen fibers fully determines the spatiotemporal fluctuations of the density and orientational order of collagen gel microstructure. Also the temperature dependence of the growth rate and nucleation rate follow the prediction of classical nucleation theory.
I型胶原蛋白在哺乳动物细胞外基质（ECM）中大量存在，对许多生物物理过程至关重要。虽然先前的研究大多集中在整体平均性质上，但在此我们提供了随着凝胶化温度变化，基于I型胶原蛋白的细胞外基质微观结构的全面定量时空表征。通过分析在广泛的凝胶化温度（从16°C到36°C）下制备的胶原蛋白凝胶的共聚焦图像，获得了包括密度和向列相关函数在内的结构特征。随着温度升高，凝胶微观结构从纤维间具有强取向相关性的“束状”网络变化为无明显取向相关性的各向同性均匀网络，这在相关函数中长度尺度的衰减中得到体现。我们开发了一个动力学蒙特卡洛胶原蛋白生长模型，以更好地理解细胞外基质微观结构如何依赖于各种环境或动力学因素。我们表明，胶原蛋白纤维的成核速率、生长速率以及有效的流体动力学排列完全决定了胶原蛋白凝胶微观结构密度和取向有序性的时空波动。此外，生长速率和成核速率的温度依赖性遵循经典成核理论的预测。
