Separation of DNA fragments for fast diagnosis by microchip electrophoresis using programmed field strength gradient.

We evaluated a novel strategy for fast diagnosis by microchip electrophoresis (ME), using programmed field strength gradients (PFSG) in a conventional glass double-T microfluidic chip. The ME-PFSG allows for the ultrafast separation and enhanced resolving power for target DNA fragments. These results are based on electric field strength gradients (FSG) that use an ME separation step in a sieving gel matrix poly-(ethylene oxide). The gradient can develop staircase or programmed shapes FSG over the time. The PFSG method could be easily used to increase separation efficiency and resolution in ME separation of specific size DNA fragments. Compared to ME that uses a conventional and constantly applied electric field (isoelectrostatic) method, the ME-PFSG achieved about 15-fold faster analysis time during the separation of 100 bp DNA ladder. The ME-PFSG was also applied to the fast analysis of the PCR products, 591 and 1191 bp DNA fragments from the 18S rRNA of Babesia gibsoni and Babesia caballi.