Biesheuvel P Maarten, Wittemann Alexander
Laboratory of Physical Chemistry and Colloid Science, Wageningen University, Dreijenplein 6, 6703 HB Wageningen, The Netherlands.
J Phys Chem B. 2005 Mar 10;109(9):4209-14. doi: 10.1021/jp0452812.
Recent experiments showed significant adsorption of bovine serum albumin (BSA) in spherical polyelectrolyte brushes (SPB) consisting of polyacrylic acid, even for pH values above the isoelectric point of the protein, when both protein and polyion are negatively charged. To describe these experimental findings theoretically, we have constructed a spherical box model for an annealed brush consisting of a weak polyelectrolyte that includes the adsorption of BSA. At equilibrium the chemical potential of BSA in solution equals that at each location in the brush, while the net force on the polyions (including osmotic, stretching, and excluded volume terms) is zero at each location. Protein adsorption is predicted above the isoelectric point and--in agreement with experimental data--is a strong function of ionic strength and pH. Adsorption of protein in the brush is possible because the pH in the brush is below the isoelectric point and protein reverses its charge from negative to positive when it adsorbs.
最近的实验表明，在由聚丙烯酸组成的球形聚电解质刷（SPB）中，牛血清白蛋白（BSA）有显著吸附，即使在蛋白质等电点以上的pH值条件下，此时蛋白质和聚离子均带负电荷。为了从理论上描述这些实验结果，我们构建了一个由弱聚电解质组成的退火刷的球形盒模型，其中包括BSA的吸附。在平衡状态下，溶液中BSA的化学势等于刷中每个位置的化学势，而聚离子上的净力（包括渗透、拉伸和排除体积项）在每个位置均为零。预测在等电点以上会发生蛋白质吸附，并且——与实验数据一致——吸附是离子强度和pH的强函数。刷中蛋白质能够吸附是因为刷中的pH低于等电点，并且蛋白质吸附时电荷从负变为正。
