Department of Chemical Physics, Hefei National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei, P R China.
Langmuir. 2013 Jun 4;29(22):6588-96. doi: 10.1021/la401069y. Epub 2013 May 22.
The conformation of polyzwitterionic brushes plays a crucial role in the adsorption/desorption of proteins on solid surfaces. By use of quartz crystal microbalance with dissipation (QCM-D) and surface plasmon resonance (SPR), we have systematically investigated the conformational behavior of poly(sulfobetaine methacrylate) (PSBMA) brushes as a function of ionic strength in the presence of different ions. The frequency change demonstrates that the effectiveness of anions to weaken the inter/intrachain association and to enhance the hydration of the grafted chains increases from kosmotrope to chaotrope in the low ionic strength regime, but the ordering of anions is almost reversed at the high ionic strengths. The dissipation change indicates that some heterogeneous structures are formed inside the brushes in the presence of chaotropic anions with the increase of ionic strength. In SPR studies, the change of resonance unit (ΔRU) with ionic strength is determined by the balance between the increase of thickness and the decrease of refractive index of the brushes. No anion specificity is observed in the SPR measurements because ΔRU is insensitive to the coupled water molecules inside the brushes. For the control of protein adsorption/desorption, our studies show that the brushes can more effectively resist the protein adsorption in the presence of a more chaotropic anion and a more chaotropic anion can also more effectively induce the protein desorption from the surface of the brushes. In addition, no obvious cation specificity can be observed in the conformational change of the brushes in either QCM-D or SPR measurements.
聚两性离子刷的构象在固体表面上蛋白质的吸附/解吸中起着至关重要的作用。我们通过使用石英晶体微天平（QCM-D）和表面等离子体共振（SPR），系统地研究了聚（磺酸甜菜碱甲基丙烯酸酯）（PSBMA）刷在存在不同离子时的离子强度的构象行为。频率变化表明，在低离子强度范围内，阴离子减弱链间/链内缔合并增强接枝链水合的有效性从同离子到离于型增加，但在高离子强度下，阴离子的有序性几乎相反。耗散变化表明，在存在离于型较强的阴离子时，随着离子强度的增加，刷内会形成一些不均匀的结构。在 SPR 研究中，随着离子强度的变化，共振单元（ΔRU）的变化取决于刷的厚度增加和折射率降低之间的平衡。SPR 测量中没有观察到阴离子特异性，因为 ΔRU 对刷内结合水分子不敏感。为了控制蛋白质的吸附/解吸，我们的研究表明，在存在更离于型较强的阴离子时，刷可以更有效地抵抗蛋白质的吸附，而更离于型较强的阴离子也可以更有效地诱导蛋白质从刷的表面解吸。此外，在 QCM-D 或 SPR 测量中，刷的构象变化都没有观察到明显的阳离子特异性。
