Xu Bin, Chow Ming-Jay, Zhang Yanhang
Department of Mechanical Engineering, Boston University, Boston, MA 02215, USA.
Int J Biomater. 2011;2011:172389. doi: 10.1155/2011/172389. Epub 2011 Aug 23.
Collagen type I scaffolds are commonly used due to its abundance, biocompatibility, and ubiquity. Most applications require the scaffolds to operate under mechanical stresses. Therefore understanding and being able to control the structural-functional integrity of collagen scaffolds becomes crucial. Using a combined experimental and modeling approach, we studied the structure and function of Type I collagen gel with the effects of spatial fiber alignment and crosslinking. Aligned collagen scaffolds were created through the flow of magnetic particles enmeshed in collagen fibrils to mimic the anisotropy seen in native tissue. Inter- and intra- molecular crosslinking was modified chemically with Genipin to further improve the stiffness of collagen scaffolds. The anisotropic mechanical properties of collagen scaffolds were characterized using a planar biaxial tensile tester and parallel plate rheometer. The tangent stiffness from biaxial tensile test is two to three orders of magnitude higher than the storage moduli from rheological measurements. The biphasic nature of collagen gel was discussed and used to explain the mechanical behavior of collagen scaffolds under different types of mechanical tests. An anisotropic hyperelastic constitutive model was used to capture the characteristics of the stress-strain behavior exhibited by collagen scaffolds.
I型胶原蛋白支架因其丰富性、生物相容性和普遍性而被广泛使用。大多数应用要求支架在机械应力下运行。因此，了解并能够控制胶原蛋白支架的结构功能完整性变得至关重要。我们采用实验和建模相结合的方法，研究了具有空间纤维排列和交联作用的I型胶原蛋白凝胶的结构和功能。通过使包裹在胶原纤维中的磁性颗粒流动，制造出排列整齐的胶原蛋白支架，以模拟天然组织中观察到的各向异性。用京尼平对分子间和分子内交联进行化学修饰，以进一步提高胶原蛋白支架的硬度。使用平面双轴拉伸试验机和平行板流变仪对胶原蛋白支架的各向异性力学性能进行了表征。双轴拉伸试验的切线刚度比流变测量的储能模量高两到三个数量级。讨论了胶原蛋白凝胶的双相性质，并用以解释胶原蛋白支架在不同类型力学测试下的力学行为。采用各向异性超弹性本构模型来描述胶原蛋白支架所表现出的应力-应变行为特征。
