Ian Wark Research Institute, University of South Australia, Mawson Lakes Blvd., Mawson Lakes, South Australia 5095, Australia.
Biomaterials. 2011 Nov;32(33):8462-73. doi: 10.1016/j.biomaterials.2011.07.064. Epub 2011 Aug 24.
The outstanding rubber-like elasticity of resilin and resilin-mimetic proteins depends critically on the level of hydration. In this investigation, water vapor sorption and the role of hydration on the molecular chain dynamics and viscoelastic properties of resilin-mimetic protein, rec1-resilin is investigated in detail. The dynamic and equilibrium swelling behavior of the crosslinked protein hydrogels with different crosslink density are reported under various controlled environments. We propose three different stages of hydration; involving non-crystallizable water, followed by condensation or clustering of water around the already hydrated sites, and finally crystallizable water. The kinetics of water sorption for this engineering protein is observed to be comparable to hydrophilic polymers with a diffusion coefficient in the range of 10(-7) cm(2) s(-1). From the comparison between the absorption and desorption isotherms at a constant water activity, it has been observed that rec1-resilin exhibits sorption hysteresis only for the tightly bound water. Investigation of molecular mobility using differential scanning calorimetry, indicates that dehydrated crosslinked rec1-resilin is brittle with a glass transition temperature (T(g)) of >180 °C, which dramatically decreases with increasing hydration; and above a critical level of hydration rec1-resilin exhibits rubber-like elasticity. Nanoindentation studies show that even with little hydration (<10%), the mechanical properties of rec1-resilin gels change dramatically. Rheological investigations confirm that the equilibrium-swollen crosslinked rec1-resilin hydrogel exhibits outstanding elasticity and resilience of ∼ 92%, which exceeds that of any other synthetic polymer and biopolymer hydrogels.
回弹蛋白和类回弹蛋白的突出橡胶弹性在很大程度上取决于水合水平。在这项研究中，详细研究了水蒸气吸附以及水合作用对类回弹蛋白蛋白 rec1-resilin 分子链动力学和粘弹性的影响。在各种控制环境下，报道了不同交联密度的交联蛋白水凝胶的动态和平衡溶胀行为。我们提出了三个不同的水合阶段；涉及不可结晶水，然后是水在已经水合的部位周围的凝结或聚集，最后是可结晶水。观察到这种工程蛋白的吸水动力学与具有 10(-7)cm(2)s(-1)范围内的扩散系数的亲水聚合物相当。从在恒定水活度下的吸收和解吸等温线的比较中，可以看出 rec1-resilin 仅在紧密结合的水处表现出吸附滞后。使用差示扫描量热法研究分子迁移率表明，脱水交联 rec1-resilin 具有脆性，玻璃化转变温度 (T(g))>180°C，随水合作用的增加而急剧下降；并且在临界水合水平以上，rec1-resilin 表现出橡胶弹性。纳米压痕研究表明，即使水合度很小（<10%），rec1-resilin 凝胶的机械性能也会发生剧烈变化。流变学研究证实，平衡溶胀的交联 rec1-resilin 水凝胶具有出色的弹性和回弹性约为 92%，超过了任何其他合成聚合物和生物聚合物水凝胶。
