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Collagen Fibrils: Nature’s Highly Tunable Nonlinear Springs
ACS Nano ( IF 17.1 ) Pub Date : 2018-03-12 00:00:00 , DOI: 10.1021/acsnano.8b00837
Orestis G. Andriotis 1 , Sylvia Desissaire 1 , Philipp J. Thurner 1
Affiliation  

Tissue hydration is well known to influence tissue mechanics and can be tuned via osmotic pressure. Collagen fibrils are nature’s nanoscale building blocks to achieve biomechanical function in a broad range of biological tissues and across many species. Intrafibrillar covalent cross-links have long been thought to play a pivotal role in collagen fibril elasticity, but predominantly at large, far from physiological, strains. Performing nanotensile experiments of collagen fibrils at varying hydration levels by adjusting osmotic pressure in situ during atomic force microscopy experiments, we show the power the intrafibrillar noncovalent interactions have for defining collagen fibril tensile elasticity at low fibril strains. Nanomechanical tensile tests reveal that osmotic pressure increases collagen fibril stiffness up to 24-fold in transverse (nanoindentation) and up to 6-fold in the longitudinal direction (tension), compared to physiological saline in a reversible fashion. We attribute the stiffening to the density and strength of weak intermolecular forces tuned by hydration and hence collagen packing density. This reversible mechanism may be employed by cells to alter their mechanical microenvironment in a reversible manner. The mechanism could also be translated to tissue engineering approaches for customizing scaffold mechanics in spatially resolved fashion, and it may help explain local mechanical changes during development of diseases and inflammation.

中文翻译:

胶原蛋白原纤维:自然界中高度可调的非线性弹簧

众所周知,组织水合作用会影响组织力学,可以通过渗透压进行调节。胶原蛋白原纤维是自然界的纳米级构建基块,可在广泛的生物组织和许多物种中实现生物力学功能。长期以来,人们一直认为原纤维内共价交联在胶原原纤维弹性中起关键作用,但主要是在远离生理菌株的地方。通过原位调节渗透压在不同水合水平下进行胶原蛋白原纤维的纳米拉伸实验在原子力显微镜实验中,我们显示了原纤维内非共价相互作用具有定义低原纤维应变时胶原原纤维拉伸弹性的能力。纳米机械拉伸试验显示,与生理盐水相比,渗透压可逆地将胶原纤维的刚度在横向(纳米压痕)提高到24倍,在纵向(张力)提高到6倍。我们将这种硬化归因于通过水合作用调节的弱分子间力的密度和强度,从而调节了胶原蛋白的堆积密度。细胞可采用这种可逆机制来以可逆方式改变其机械微环境。该机制也可以转化为组织工程方法,以空间解析的方式自定义脚手架力学,
更新日期:2018-03-12
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