Simultaneous Concentration and Separation of Proteins in a Nanochannel


  • This work was supported by grants from the Australian Research Council (DP0880205, DP110102207). Thermal oxidation was performed at the University of New South Wales node and photomasks were made at the Optofab node of the Australian National Fabrication Facility, established under NCRIS. We also thank R.H. Austin and M.S. Baker for helpful discussions.


original image

Balancing the forces: Conductivity gradient focusing in a nanochannel achieves simultaneous separation and concentration of proteins without a temperature gradient, membrane, matrix, ampholytes, or external pump. The electrophoretic force (see picture; red arrow) that dominates at the low-salt side (−) balances the electro-osmotic force (blue) at the high-salt side (+).