Physical and Theoretical Chemistry Laboratory, Oxford University, South Parks Road, Oxford, United Kingdom.
Langmuir. 2011 Sep 20;27(18):11316-23. doi: 10.1021/la201706p. Epub 2011 Aug 18.
The adsorption of the surface-active protein hydrophobin, HFBII, and the competitive adsorption of HFBII with the cationic, anionic, and nonionic surfactants hexadecyltrimethylammonium bromide, CTAB, sodium dodecyl sulfate, SDS, and hexaethylene monododecyl ether, C(12)E(6), has been studied using neutron reflectivity, NR. HFBII adsorbs strongly at the air-water interface to form a dense monolayer ∼30 Å thick, with a mean area per molecule of ∼400 Å(2) and a volume fraction of ∼0.7, for concentrations greater than 0.01 g/L, and the adsorption is independent of the solution pH. In competition with the conventional surfactants CTAB, SDS, and C(12)E(6) at pH 7, the HFBII adsorption totally dominates the surface for surfactant concentrations less than the critical micellar concentration, cmc. Above the cmc of the conventional surfactants, HFBII is displaced by the surfactant (CTAB, SDS, or C(12)E(6)). For C(12)E(6) this displacement is only partial, and some HFBII remains at the surface for concentrations greater than the C(12)E(6) cmc. At low pH (pH 3) the patterns of adsorption for HFBII/SDS and HFBII/C(12)E(6) are different. At concentrations just below the surfactant cmc there is now mixed HFBII/surfactant adsorption for both SDS and C(12)E(6). For the HFBII/SDS mixture the structure of the adsorbed layer is more complex in the region immediately below the SDS cmc, resulting from the HFBII/SDS complex formation at the interface.
表面活性蛋白疏水蛋白 HFBII 的吸附以及 HFBII 与阳离子、阴离子和非离子表面活性剂十六烷基三甲基溴化铵（CTAB）、十二烷基硫酸钠（SDS）和六亚乙基单十二醚（C(12)E(6)）的竞争吸附已使用中子反射率（NR）进行了研究。HFBII 在空气-水界面强烈吸附形成约 30 Å厚的致密单层，对于浓度大于 0.01 g/L 的浓度，每个分子的平均面积约为 400 Å(2)，体积分数约为 0.7，并且吸附与溶液 pH 无关。在 pH 7 时与常规表面活性剂 CTAB、SDS 和 C(12)E(6)竞争时，HFBII 吸附在表面活性剂浓度小于临界胶束浓度（cmc）时完全主导表面。在常规表面活性剂的 cmc 以上，HFBII 被表面活性剂（CTAB、SDS 或 C(12)E(6)）取代。对于 C(12)E(6)，这种取代是部分的，对于浓度大于 C(12)E(6)cmc 的浓度，一些 HFBII 仍留在表面。在低 pH（pH 3）下，HFBII/SDS 和 HFBII/C(12)E(6)的吸附模式不同。在表面活性剂 cmc 以下的浓度下，现在对于 SDS 和 C(12)E(6)，都存在混合的 HFBII/表面活性剂吸附。对于 HFBII/SDS 混合物，在 SDS cmc 以下的区域，吸附层的结构更加复杂，这是由于界面处 HFBII/SDS 复合物的形成所致。
