Pluronics are triblock copolymers of poly(ethylene oxide) -poly(propylene oxide)-poly (ethylene oxide) that are able to form many different ordered nanostructures at appropriate polymer concentrations and temperatures in selective solvents. These nanostructured "gels" showed desirable criteria when used as DNA separation media, especially in microchip electrophoresis, including dynamic coating and viscosity switching. A ternary system of F127 (E99P69E99)/TBE buffer/1-butanol was selected as a model system to test the sieving performance of different nanostructures in separating dsDNA by CE. The nanostructures and their lattice constants were determined by small-angle X-ray scattering. Viscosity measurements showed the sol-gel transition phenomena. In addition to the cubic structure, successful electrophoretic separation of dsDNA in 2-D hexagonally packed cylinders was achieved. Results showed that without further optimization, Phi X174 DNA-Hae III digest was well separated within 15 min in a 7-cm. separation channel, by using F127/TBE/1-butanol gel with a 2-D hexagonal structure. A mechanism for DNA separations by those gels with both hydrophilic and hydrophobic domains is discussed.