Design of a new, twelve-channel electrophoretic apparatus based on the Gradiflow technology

The Gradiflow technology, originally designed to carry out binary, size-based and charge sign-based electrophoretic protein separations, has been extended to simultaneously obtain multiple protein fractions from a single electrophoretic separation. The separation unit of the new apparatus houses the anode and cathode compartments and up to twelve shallow separation compartments through which the background electrolyte solution that contains the separated protein fractions is recirculated. The separation compartments are formed from grids as thin as 1.2 mm and polyacrylamide membranes as thin as 0.15 mm, all with corresponding multiple inlet and outlet ports. The average pore size of the polyacrylamide membranes can be varied to permit passage of proteins in the 5000–800 000 molecular mass range. The electric field, orthogonal to the flow paths of the recirculated background electrolyte, selectively moves the sample components across the polyacrylamide separation membranes. Selective protein transport can be achieved by exploiting differences in either the relative size of the proteins or the charge sign of the proteins. The advantages of the new apparatus stem from the synergistic combination of the short electrophoretic transfer distances, high electric field strength, large effective surface areas of the separation membranes, and the great flexibility with which apparati containing one to twelve separation compartments can be created.