Nano-Science Center, Institute of Sports Medicine Copenhagen, Bispebjerg Hospital and Center for Healthy Aging, Faculty of Health Science, University of Copenhagen, Copenhagen, Denmark.
Biophys J. 2010 Dec 15;99(12):4020-7. doi: 10.1016/j.bpj.2010.11.018.
To carry out realistic in vitro mechanical testing on anatomical tissue, a choice has to be made regarding the buffering environment. Therefore, it is important to understand how the environment may influence the measurement to ensure the highest level of accuracy. The most physiologically relevant loading direction of tendon is along its longitudinal axis. Thus, in this study, we focus on the tensile mechanical properties of two hierarchical levels from human patellar tendon, namely: individual collagen fibrils and fascicles. Investigations on collagen fibrils and fascicles were made at pH 7.4 in solutions of phosphate-buffered saline at three different concentrations as well as two HEPES buffered solutions containing NaCl or NaCl + CaCl2. An atomic force microscope technique was used for tensile testing of individual collagen fibrils. Only a slight increase in relative energy dissipation was observed at the highest phosphate-buffered saline concentration for both the fibrils and fascicles, indicating a stabilizing effect of ionic screening, but changes were much less than reported for radial compression. Due to the small magnitude of the effects, the tensile mechanical properties of collagen fibrils and fascicles from the patellar tendon of mature humans are essentially insensitive to environmental salt concentration and composition at physiological pH.
为了对解剖组织进行现实的体外力学测试，必须选择缓冲环境。因此，了解环境如何影响测量结果以确保最高的准确性非常重要。肌腱最接近生理的加载方向是沿着其纵轴。因此，在这项研究中，我们专注于来自人髌腱的两个层次的拉伸力学性能，即：单个胶原原纤维和原纤维束。在 pH 值为 7.4 的条件下，在磷酸盐缓冲生理盐水的三种不同浓度以及两种含有 NaCl 或 NaCl+CaCl2 的 HEPES 缓冲溶液中对胶原原纤维和原纤维束进行了研究。原子力显微镜技术用于测试单个胶原原纤维的拉伸性能。仅在最高磷酸盐缓冲生理盐水浓度下观察到原纤维和原纤维束的相对能量耗散略有增加，表明离子屏蔽具有稳定作用，但变化远小于径向压缩的报道。由于影响的幅度较小，成熟人髌腱胶原原纤维和原纤维束的拉伸力学性能在生理 pH 值下基本不受环境盐浓度和组成的影响。
