Effect of applied uniaxial stress on rate and mechanical effects of cross-linking in tissue-derived biomaterials
Effect of applied uniaxial stress on rate and mechanical effects of cross-linking in tissue-derived biomaterials
复制标题
DOI：
10.1016/0142-9612(95)00305-3
复制
发表时间：
1996-10-01
期刊：
影响因子：
14
通讯作者：
Lee, JM
中科院分区：
文献类型：
--
作者：
Chachra, D;Gratzer, PF;Lee, JM
胶原原纤维的构象变化，实际上是三螺旋结构，可以通过施加机械应力或应变而产生。我们已经证明戊二醛和环氧化物均双功能试剂的交联速率可以通过单轴应力（应变）来调节。使用两种聚缩水甘油酯环氧化物：Denacol(R) EX-810（小型双功能试剂）和Denacol EX-512（大型多功能试剂）。为了防止任何可能的影响被交联位点的饱和所掩盖，牛心包被交联到这样的程度，即胶原变性温度的增加，T-d，是每种试剂可达到的最大上升的一半。交联时施加的单轴拉应力分别为0、15、124或233 kPa。交联速率（通过T-d的增加观察到）随着胁迫的增加而增加，pH为7时戊二醛在124 kPa时达到最大值，而EX-810在pH为7时则降低。在每种情况下，影响都很小，但在统计上是显著的。较大的EX-512未观察到任何影响。增加应力下的交联对材料的力学性能也有系统的影响：降低拉伸和塑性应变，提高抗拉强度。在每种情况下，环氧化物的作用与戊二醛的作用略有不同。在准备上述实验时，研究了pH值、温度和暴露时间对每种环氧化物的影响，并（在较小程度上）对戊二醛进行了研究。再一次，随着T-d的增加，观察到机械性能的系统性变化。由机械应力（应变）产生的胶原构象变化调节交联速率和由此产生的力学性能；然而，效果对所用的试剂很敏感。(C) 1996 Elsevier Science Limited
Conformational changes in collagen fibrils, and indeed the triple helix, can be produced by application of mechanical stress or strain. We have demonstrated that the rate of cross-linking in glutaraldehyde and epoxide homobifunctional reagents can be modulated by uniaxial stress (strain). Two poly(glycidyl ether) epoxides were used: Denacol(R) EX-810 (a small bifunctional reagent), and Denacol EX-512 (a large polyfunctional reagent). To prevent any possible effect from being masked by saturation of cross-linking sites, bovine pericardium was cross-linked to such an extent that the increase in collagen denaturation temperature, T-d, was one-half of the maximal rise achievable with each reagent. Uniaxial tensile stress of 0, 15, 124 or 233 kPa was applied during cross-linking. Cross-linking rate (as observed by increase in T-d) increased with increasing stress to a maximum at 124 kPa in glutaraldehyde at pH 7 but decreased in EX-810 at pH 7. In each case, the effect was small but statistically significant. No effect was observed with the larger EX-512. Cross-linking under increasing stress also showed systematic effects on mechanical properties: decreasing extensibility and plastic strain while increasing tensile strength. In each case, the effects of the epoxides were slightly different from those of glutaraldehyde. In preparation for the above experiments, studies of the effect of pH, temperature, and exposure time were carried out for each epoxide and (to a lesser extent) for glutaraldehyde. Again, systematic changes in mechanical properties were observed with increasing T-d. Conformational changes in collagen produced by mechanical stress (strain) modulate the rate of cross-linking and the resulting mechanical properties; however, the effects are sensitive to the reagent employed. (C) 1996 Elsevier Science Limited