(366c) Size Exclusion Electrofocusing In Nanochannels

The standard method for protein sizing, SDS-PAGE, is cumbersome, slow, difficult to automate, and requires that protein bands be excised from the gel prior to further analysis. Capillary and microchip formats for performing SDS-PAGE have emerged as alternatives to the “slab gel” format, but have failed to displace traditional SDS-PAGE because of the relatively long runtimes required and the need for a pre-concentration "stacking" step to increase resolution.

In this paper, we consider replacing SDS-PAGE with an electrofocusing method that separates proteins on the basis of their molecular weights. Proteins and other nanoparticles can be simultaneously separated and concentrated according to their size in channels and/or pores whose dimensions are several times larger than the particles. In porous media such as monoliths, size-based electrofocusing can be conducted if there is a gradient in the properties of the pores while open nano-channels require a gradient in the channel properties to do this.

This paper will discuss how size-based electrofocusing can be carried out in several different media, the resolving power that can be expected from this technique, and how mathematical models can be used to describe these separations.