Department of Chemistry, Royal Institute of Technology, Stockholm, Sweden.
Colloids Surf B Biointerfaces. 2010 May 1;77(1):1-11. doi: 10.1016/j.colsurfb.2009.12.019. Epub 2010 Jan 15.
The adsorbed amount and layer structure of lysozyme, beta-casein and mixed layers of the two proteins were studied on hydrophilic silica and quartz surfaces using the following techniques: ellipsometry, quartz crystal microbalance with dissipation monitoring (QCM-D) and total internal reflection fluorescence (TIRF). Particular emphasis was put on the effect of solution ionic strength on the layer formation. Both lysozyme and beta-casein showed a higher affinity for the silica surface when adsorbed from a solution of low ionic strength even though beta-casein and silica are negatively charged at the pH used. No beta-casein remained adsorbed after rinsing with a 150mM buffer solution. The adsorbed amount of lysozyme on silica exceeded a monolayer coverage irrespective of the solution conditions and displayed a rigid structure. beta-Casein forms more than a single layer on pre-adsorbed lysozyme; an inner flat layer and an outer layer with an extended structure, which largely desorbs on rinsing. The build-up through sequential adsorption of lysozyme and beta-casein is favoured at intermediate and high ionic strength. The total adsorbed amount increased slightly with each deposition cycle and the mixed lysozyme/beta-casein layers contain higher amounts of protein compared to those of pure lysozyme or beta-casein. Sequential adsorption gives rise to a proteinaceous layer consisting of both lysozyme and beta-casein. The protein layers are probably highly interpenetrated with no clear separation between them.
采用椭圆偏振法、石英晶体微天平（QCM-D）和全内反射荧光（TIRF）技术，研究了溶菌酶、β-酪蛋白及其两者混合层在亲水二氧化硅和石英表面上的吸附量和层结构。特别强调了溶液离子强度对层形成的影响。尽管β-酪蛋白和二氧化硅在使用的 pH 值下带负电荷，但当从低离子强度溶液中吸附时，溶菌酶和β-酪蛋白对二氧化硅表面的亲和力更高。用 150mM 缓冲溶液冲洗后，没有β-酪蛋白残留吸附。溶菌酶在二氧化硅上的吸附量超过单层覆盖，无论溶液条件如何，均显示出刚性结构。β-酪蛋白在预先吸附的溶菌酶上形成多个单层；内层为平面层，外层为伸展结构，在冲洗时大部分解吸。在中间和高离子强度下，通过溶菌酶和β-酪蛋白的顺序吸附进行组装是有利的。每次沉积循环都会使总吸附量略有增加，并且与纯溶菌酶或β-酪蛋白相比，混合溶菌酶/β-酪蛋白层含有更多的蛋白质。顺序吸附产生了由溶菌酶和β-酪蛋白组成的蛋白质层。这些蛋白质层可能高度交织，彼此之间没有明显的分离。
