Sponge‐like electrophoresis media: Mechanically strong materials compatible with organic solvents, polymer solutions and two‐dimensional electrophoresis

Publisher Website
Google Scholar
Abstract
A new range of sponge‐like media, called “electrophoresis sponges”, is presented. They differ from electrophoresis gels primarily in that they are mechanically stronger, providing a permanent structure of directly measurable pore size dimensions. The new media are similar to capillary electrophoresis in terms of pore size range, they are mechanically strong with directly definable walls, and are compatible with polymer solutions. The sponges differ from capillary electrophoresis in that they provide large numbers of channels, with a corresponding high load capacity for simultaneous runs in multiple channels and they are compatible directly with multi‐dimensional separations, such as high resolution two‐dimensional electrophoresis. Furthermore, they can be molded (or cut) to any shape and retain that shape, they can be handled more easily than gels, they can be reused if necessary, they can be distributed in the same format between labs easily, and they can be stored indefinitely. Chemically, they can be hydrophilic or hydrophobic, with capability ranging from inert to reactive surfaces. Pore sizes can range from the sub‐nanometer to 100 micron scale. Results with various hydrophobic sponges are reported for the carrier ampholyte‐based isoelectric focusing of proteins. Broad and narrow pH gradients are established in the sponges that are more linear than those achieved with polyacrylamide gels. One‐ and two‐dimensional electrophoresis of proteins has been achieved, for example with high resolution of the charge isomers of the haptoglobin beta chain, using sponge‐based isoelectric focusing. Isoelectric focusing is about threefold faster in the tested sponges than in equivalent polyacrylamide gels. This improved speed is probably related to the larger sponge pores. Moreover, both the quantity of sample entry of the hydrophobic protein zein and its resolution after isoelectric focusing in the electrophoresis sponges (in the presence of organic solvent) was superior to that achieved in polyacrylamide gels. Experimentation and the application of these electrophoresis sponges is still preliminary, but the sponges appear to have potential as alternatives to the existing media used for electrophoresis.