A Patterned Anisotropic Nanofilter Array for Continuous-Flow Separation of DNA and Proteins

Microfabricated regular sieving structures hold great promise as an alternative to gels to improve biomolecule separation speed and resolution. In contrast to the disordered gel porous network, these regular structures also provide well-defined environments ideal for study of molecular dynamics in confining spaces. However, previous regular sieving structures have been limited for separation of long DNA molecules, and separation of smaller, physiologically- relevant macromolecules, such as proteins, still remains as a challenge. Here we report a microfabricated anisotropic sieving structure consisting of a two-dimensional periodic nanofluidic filter array (an Anisotropic Nanofilter Array, or ANA). The designed structural anisotropy in the ANA causes differently-sized molecules to follow different trajectories, leading to efficient separation. Continuous-flow Ogston sieving-based separation of short DNA and proteins as well as entropic trapping-based separation of long DNA were achieved, thus demonstrating the potential of the ANA as a generic sieving structure for an integrated biomolecule sample preparation and analysis system.