Continuous Multicomponent Focusing of Solutes and Particles Using Spatially Stabilized pH

这项研究建议使用磁稳定的流态床(MSFB)通过不同的等电值(即分子不带电荷的pH)来分离两性离子分子(即含有正负电荷部分的分子)。该流态化床由一个管子组成，其中带负电荷的树脂颗粒从管子的顶部加入，流态化液体从管子的底部分布。从底部去除颗粒，从顶部去除液体，从而实现连续操作。通过在高pH下插入液体进料和在低pH下插入固体颗粒，在床中保持pH梯度。含有溶解的溶质的混合物(其中一种是要分离的)被送入液流中靠近底部的某处，并进入柱子的一侧。当溶质在液体运动的作用下沿床层向上移动时，溶质所处的局部pH值降低。局部pH的降低导致溶质最终带正电(在床层中局部pH等于溶质等电值位置的正上方)。一旦带正电，溶质就与带负电的树脂静电结合，并与树脂颗粒一起被带到柱子的底部。当它沿着柱子下降时，局部的pH值下降，这导致溶质反转其电荷，从树脂颗粒中移出，并被夹带在向上流动的液体中。因此，溶质被困在柱子中某一水平的狭窄区域中，在那里，局部pH等于溶质的等电点。理想情况下，混合物中的溶质将在柱中分离成占据不同水平的区域。通过从这些区域提取液体和固体，可以获得富含一种溶质的液体，从而实现分离。这项拟议的研究将开发一个工作原型，并研究该床在准备生物分子分离方面的有效性。

This study proposes using a magnetically stabilized fluidized bed (MSFB) to separate zwitterionic molecules (i.e., molecules containing negatively and positively charged moieties) by virtue of differing isoelectric values (i.e., the pH at which the molecule is not charged). The fluidized bed consists of a tube in which negatively charged resin particles are added from the top of the tube, and the fluidizing liquid is distributed from the bottom. Removal of the particles from the bottom, and liquid from the top allows for continuous operation. A pH gradient is maintained in the bed by inserting the liquid feed at a high pH and the solid particles at a low pH. A mixture containing dissolved solutes (one of which is targeted for separation) is fed into the liquid stream somewhere near the bottom, and to one side of the column. As the solute moves up the bed by virtue of the liquid motion, the local pH that the solute is exposed to decreases. The reduction in the local pH causes the solutes to eventually become positively charged (at the positions in the bed just above the positions where the local pH is equal to the isoelectric values of the solutes). Once positively charged, the solute binds electrostatically to the negatively charged resin, and is carried with the resin particles down to the bottom of the column. As it descends down the column, the local pH decreases, and this causes the solute to reverse its charge, remove itself from the resin particle, and become entrained in the upflowing liquid. The solute thus becomes trapped in a narrow zone at a level in the column where the local pH is equal to the solute's isoelectric point. Ideally, the solutes in the mixture will separate out into zones occupying different levels in the column. By withdrawing fluid and solid from these zones, liquid rich in one solute can be obtained, thereby effecting the separation. The proposed research will develop a working prototype, and scope the effectiveness of the bed to prepare separations of biological molecules.