β-casein and symmetrical triblock copolymer (PEO-PPO-PEO and PPO-PEO-PPO) surface properties at the air-water interface
β-casein and symmetrical triblock copolymer (PEO-PPO-PEO and PPO-PEO-PPO) surface properties at the air-water interface
复制标题
DOI：
10.1021/la030294c
复制
发表时间：
2004-02-03
期刊：
影响因子：
3.9
通讯作者：
Douillard, R
中科院分区：
文献类型：
--
作者：
Hambardzumyan, A;Aguié-Béghin, V;Douillard, R
用气泡张力仪和椭偏仪比较了β-酪蛋白和对称三嵌段共聚物(PEO-PPO-PEO和PPO-PEO-PPO)在空气-水界面的吸附性能。由Brewster条件下的表面压力(Pi)和椭圆度((Rho)/bar(B))得到的与表面浓度(Gamma)数据成正比的状态参数(pi类似于Gamma(Y))，与由膨胀模epsilon和pi得到的数据相同。这两个一致的方法进一步支持了先前为蛋白质在流体界面吸附而开发的嵌段共聚物的理论模型。结果表明，共聚物吸附层的界面行为随亲水嵌段序列和疏水嵌段序列的长度变化很大。只有当嵌段尺寸足够大时，理论模型才能用于解释合成共聚物的吸附性能。在嵌段共聚物的情况下，无论温度如何，线圈都是自避免的行走构象(y=3)，而在β-酪蛋白的情况下，多肽链在室温下由于不热的非共价键而部分折叠。在第一个半稀释阶段结束时，有明显的证据表明，合成共聚物和β-酪蛋白有向第二个半稀释阶段过渡的迹象，但目前只有部分特征。
A comparison of beta-casein and symmetrical triblock copolymer (PEO-PPO-PEO and PPO-PEO-PPO) adsorption layer properties at the air-water interface has been carried out by bubble tensiometry and ellipsometry. It has been verified that the equation of state parameters (pi similar to Gamma(y)) obtained from surface pressure (pi) and ellipticity in Brewster conditions ((rho) over bar (B)), which is proportional to the surface concentration (Gamma) data, are the same as those obtained from dilational modulus epsilon and pi data. These two consistent approaches give further support to the theoretical model of block copolymers which has been previously developed for protein adsorption at fluid interfaces. It is shown that the interfacial behavior of the copolymer adsorption layer changes strongly as a function of the length of the hydrophilic and hydrophobic block sequences. The theoretical model may be used for the interpretation of the adsorption properties of the synthetic copolymers only when the size of the blocks is large enough. In the case of block copolymers, the coil is in a self-avoiding walk conformation (y = 3) whatever the temperature, while in the case of beta-casein, the polypeptide chain is partly collapsed at room temperature due to thermolabile noncovalent bonds. At the end of the first semidilute regime, there is clear evidence for a crossover toward a second semidilute regime for synthetic copolymers as well as for beta-casein but it is presently only partially characterized.