Nanotech News

August 1, 2005

Nanofluidics Produces Million-Fold Concentration of Proteins

A new nanoscale filter capable of concentrating proteins on a microfluidic device could provide a critical boost to efforts aimed at identifying rare proteins associated with early-stage cancers. The nanofluidic filter was developed by Jongyoon Han, Ph.D., and colleagues at the Massachusetts Institute of Technology.

Writing in the journal Analytical Chemistry, the MIT investigators noted that proteomics research suffers from the lack of an efficient means of concentrating biological fluids so that rare proteins can be separated and identified sensitively on microfluidics devices. To solve this problem, the researchers turned to two complex physical processes known as electrokinetic trapping and nonlinear electroosmotic flow to rapidly concentrate proteins by a factor of at least a million-fold within the confines of a nanofluidic channel. These two physical effects result from the fact that an electric field applied across a nanofluidic channel causes charged molecules to distribute unequally across the channel. This charge separation creates what is in essence a virtual nanoscale filter — without the presence of a physical membrane — that is capable of trapping proteins without impeding the flow of the protein-containing fluid.

The researchers note that this virtual filter is remarkably stable, which allows proteins to be concentrated over the course of hours if necessary. In one experiment, this device achieved a 10-million-fold concentration increase over a one hour period. Once the desired concentration increase is achieved, the electric field is turned off, allowing a band of protein to move through the nanofluidic channel to other parts of a microfluidic device, such as an electrophoresis protein separator.

This work appears in a paper titled, “Million-fold preconcentration of proteins and peptides by nanofluidic filter." This paper was posted online in advance of print publication. An abstract of this paper is available at the journal’s website.
View abstract.