McClellan Scott J, Franses Elias I
School of Chemical Engineering, Purdue University, 480 Stadium Mall Drive, West Lafayette, Indiana 47907-2100, USA.
Langmuir. 2005 Oct 25;21(22):10148-53. doi: 10.1021/la050579k.
The competitive adsorption of proteins and surfactants has applications to chromatographic systems and biological materials. Adsorption for systems of bovine serum albumin (BSA) and sodium myristate (SM) was investigated with in-situ ATR-IR spectroscopy and ex-situ ellipsometry. The results were used to determine quantitatively the surface densities of the adsorbates at the surface. For a mixture of SM and BSA at 25 degrees C in water, the adsorbed density of BSA is 0.3 mg/m2, which is much less than the value of 3.1 mg/m2 for BSA alone. Sodium myristate, some of which is protonated to myristic acid (MA) when adsorbed because of a pH decrease from 9.0 to 8.2, adsorbs to a surface density of 4.0 x 10(-6) mol/m2, which is greater than the value of 1.7 x 10(-6) mol/m2 from a solution of SM alone. Adsorbed SM and MA are removed, or desorbed, when the bulk mixture is replaced with water, with only a slight amount of SM remaining. When placed in contact with a layer of BSA, SM can displace most of the adsorbed protein, even when BSA is present in the bulk solution, with some BSA at 0.3 mg/m2 remaining adsorbed. Allowing BSA to adsorb to a layer of SM results in gamma(BSA) = 2.3 mg/m2, with little displacement of the SM layer. These results indicate that SM can remove some BSA from the surface by displacement, and that some BSA remains adsorbed in patches.
蛋白质和表面活性剂的竞争吸附在色谱系统和生物材料方面有应用。采用原位衰减全反射红外光谱（ATR-IR）和非原位椭偏仪研究了牛血清白蛋白（BSA）和肉豆蔻酸钠（SM）体系的吸附情况。这些结果用于定量测定吸附质在表面的表面密度。对于25℃水中SM和BSA的混合物，BSA的吸附密度为0.3 mg/m²，远低于单独BSA时3.1 mg/m²的值。肉豆蔻酸钠在吸附时由于pH从9.0降至8.2，部分质子化形成肉豆蔻酸（MA），其吸附的表面密度为4.0×10⁻⁶ mol/m²，大于单独SM溶液时1.7×10⁻⁶ mol/m²的值。当用纯水替换本体混合物时，吸附的SM和MA会被去除或解吸，仅残留少量SM。当与一层BSA接触时，即使本体溶液中存在BSA，SM也能取代大部分吸附的蛋白质，仍有0.3 mg/m²的一些BSA残留吸附。使BSA吸附到一层SM上时，γ(BSA)=2.3 mg/m²，SM层几乎没有被取代。这些结果表明，SM可通过取代作用从表面去除一些BSA，且一些BSA仍以斑块形式残留吸附。
