盐酸胍/Ⅰ型胶原分散体系的流变性

采用胃蛋白酶降解法从猪皮中提取了胶原蛋白, 用十二烷基硫酸钠-聚丙烯酰胺凝胶电泳(SDS-PAGE)确定为Ⅰ型胶原; 红外及紫外光谱表明胶原分子中存在三螺旋结构. 分别采用小幅振荡剪切法、 恒定剪切速率法及滞后环法研究了盐酸胍浓度及作用时间对Ⅰ型胶原蛋白体系流变性的影响. 研究表明, 随盐酸胍浓度的增大及作用时间的延长, 盐酸胍/胶原分散体系由假塑性流体逐渐接近于牛顿流体. 在所研究的盐酸胍浓度范围(0~6.0 mol/L)内, 盐酸胍/胶原分散体系的触变性类型随盐酸胍浓度的增大发生正触变性-复合触变性-负触变性的转变; 随盐酸胍作用时间的延长(6~48 h), 盐酸胍浓度为1.0 mol/L的胶原分散体系的触变性类型发生复合触变性-负触变性的转变. 本文的研究结果有助于加深对触变性产生机理的认识.

Rheological Properties of GuHCl/Type Ⅰ Collagen Dispersions†

Collagen was extracted from the outer skin of pig using a pepsin digestion method. The isolated collagen was characterized by sodium dodecyl sulfate-polyacrylamide gel electrophoresis(SDS-PAGE), Fourier transform infrared spectroscopy(FTIR) and ultraviolet(UV). According to the electrophoretic pattern, the isolated collagen consisted of two different α-chains(α₁, α₂) and one β-chain, indicating type Ⅰ collagen. FTIR and UV results confirmed the presence of triple helical structure in the collagen molecule. The rheological properties of GuHCl/type Ⅰ collagen dispersions were investigated as a function of guanidine hydrochloride(GuHCl) concentration and action time. The results of flow curves indicated that the pseudoplastic flow behavior of GuHCl/collagen dispersions gradually close to the Newtonian fluid with the increase of GuHCl concentration in the range of 0—6.0 mol/L and action time in the range of 6—48 h. The linear oscillatory shear, steady shear and thixotropic loop experiments were performed to investigate thixotropic behavior of the GuHCl/collagen dispersions. It was found that the thixotropic type of GuHCl/collagen dispersions transformed from positive thixotropy to complex thixotropy and then to negative thixotropy with the increase of GuHCl concentration. The thixotropic type of collagen dispersion transformed from complex thixotropy to negative thixotropy with the increase of action time of 1.0 mol/L GuHCl. It should be note that the complex thixotropy in GuHCl/collagen dispersions has not been reported in the similar systems so far. And we tentatively discussed this novel discovery on the basis of the interactions between GuHCl molecule and collagen. Meanwhile, this work would be helpful to deeply understand the mechanism of thixotropy.