Laboratory of Food Process Engineering, Wageningen University, Bornse Weilanden 9, Wageningen 6708 WG, The Netherlands.
School of Chemical and Biomedical Engineering, Nanyang Technological University, 62 Nanyang Drive, 637459, Singapore.
Langmuir. 2021 Jun 1;37(21):6549-6555. doi: 10.1021/acs.langmuir.1c00828. Epub 2021 May 19.
When proteins in aqueous solutions are exposed to solid substrates, they adsorb due to the dynamic interplay of electrostatic, van der Waals, and hydration interactions and do so in a rather irreversible fashion, which makes protein recovery troublesome. Here, we use a gold electrode as the solid substrate and modulate the surface potential to systematically induce protein adsorption as well as partial desorption. We use different methods such as surface plasmon resonance, atomic force microscopy, and electrowetting and show that biasing the electrode to more negative potentials (by -0.4 V compared to the open-circuit potential at pH 6) results in an increased adsorption barrier of 6 kJ mol for the negatively charged protein β-lactoglobulin. Further, we clearly demonstrate that this is due to an increased double layer potential of -0.06 V and an increase in hydration repulsion. This indicates that an electric potential can directly influence surface interactions and thus induce partial β-lactoglobulin desorption. These observations can be the basis for biosensors as well as separation technologies that use to steer protein ad- and desorption, which is low in energy requirement and does not generate large waste streams, as is the case for standard protein separation technologies.
当蛋白质在水溶液中暴露于固体基质时，由于静电、范德华和水合相互作用的动态相互作用，它们会发生吸附，而且这种吸附往往是不可逆的，这使得蛋白质的回收变得很麻烦。在这里，我们使用金电极作为固体基质，并调节表面电势以系统地诱导蛋白质吸附和部分解吸。我们使用不同的方法，如表面等离子体共振、原子力显微镜和电润湿，并表明将电极偏置到更负的电位（与 pH 6 时的开路电位相比为 -0.4 V）会导致带负电荷的蛋白质β-乳球蛋白的吸附势垒增加 6 kJ mol。此外，我们清楚地表明，这是由于双电层电位增加了-0.06 V 和水化排斥的增加。这表明电势可以直接影响表面相互作用，从而诱导部分β-乳球蛋白解吸。这些观察结果可以为生物传感器以及使用电势来控制蛋白质吸附和解吸的分离技术提供基础，这种方法的能量需求低，而且不会产生大量的废物，这与标准的蛋白质分离技术不同。
