Ultrafiltration Can Retain Biological Activity And Save Time
Ultrafiltration can retain biological activity and save time. Protein purification technology has developed from various chemical precipitation methods for sample enrichment or dialysis methods for buffer exchange to pressure driven purification cross flow system using ultrafiltration membrane. Ultrafiltration (UF) technology relies on the use of polymeric membranes with high-level defined pore sizes to separate molecules according to size. In short, the ultrafiltration (UF) step uses liquid pressure to promote the transfer of smaller molecules through the ultrafiltration (UF) membrane and intercept larger molecules at the same time.
Chemical precipitation method can be used to concentrate protein samples. Ultrafiltration based separation is more based on mechanical action than chemical reaction. Researchers can concentrate samples without adding denatured solvents or salts. Buffer exchange using dialysis technology uses a large amount of buffer. Since the only force acting on the solvent is diffusion force, the process will last for several days. The pre assembled and easy-to-use ultrafiltration device can quickly perform the concentration or buffer exchange steps without the cumbersome treatment process required by many other technologies.
Ultrafiltration can be implemented in either of the following two operation modes: direct flow filtration (DFF) or tangential flow filtration (TFF, figure 1). DFF has a good effect on the treatment process of small flow (up to 30ml) with centrifugal device, but DFF technology will be adversely affected by the problem of membrane blockage. In order to reduce the formation of colloidal layer, a floating stirring rod configuration (stirring tank) can be used or a cross flow can be generated on the upstream side of the diaphragm by generating a controlled laminar flow. The operation of stirring rod can improve the ultrafiltration effect, but there are still limitations in obtaining the best performance. Because the stirring speed and timing level depend on the swing range of the rod body, and this range will change with the change of the swing radius.
