Electrophoretic Separation Of Antisense Dna Using Polymer-Solution Filled Capillary By Cross-Injection

Different lengths of antisense DNA are normally separated by polyacrylamide gel-filled column using capillary electrophoresis. The rigid gel bed, however, has a limited lifetime due to the forming of air bubbles and clogging particularly wen a real sample with complex matrix is analyzed. An alternative is to replace the gel with a replenishable polymer solution. In this work, a capillary electrophoresis system using a microcross (10 nL) connected with four 75 mu m i.d. fused-silica capillaries and operated under high-voltage shunting is described to implement the PEG sieving medium for the separation of antisense DNAs. Both the separation and injection capillaries were filled with polyethylene glycol (PEG) in tris-borate buffer and the separation was performed with pinched-mode. The PEG medium was found to resolve the 15-20mers of antisense DNA under a conventional linear configuration. Substantial band broadening, however, was observed when using the cross configuration under the same separation conditions. A better control of the injection time as well as the applied voltage is required to minimize the sample diffusion.