ZnO Nanowires for DNA Electrophoresis

Professor Kevin Dorfman, Professor Eray Aydil and colleagues at the University of Minnesota have developed a method to integrate ZnO nanowires into a microfluidic device for DNA electrophoresis. The classical method for separating long DNA, known as pulsed-field electrophoresis, requires hours to days to achieve adequate resolution. Recent work demonstrated that the same separations can be performed in arrays of nano-sized posts in the manner of minutes. Unfortunately, these so-called “nanopost arrays” require expensive, time consuming clean room fabrication methods. In the method developed at the University of Minnesota, the nanoposts are grown from solution into a specified region of a glass microchannel. As a result, the cost-limiting nanopatterning step is eliminated. Moreover, the density of the nanowires is easily controlled by the surface preparation prior to nanowire growth. The Minnesota team used a sparse array of nanowires to perform a fundamental study of the collision of a large DNA molecule with an isolated nanowire, whose physics lie at the heart of the separation process. In addition to confirming a number of theoretical predictions, they discovered a new dynamic criterion governing the collision process. The fabrication method developed here could be used in large-scale manufacture of inexpensive DNA separation microdevices.