Million-fold preconcentration of proteins and peptides by nanofluidic filter.

We have developed a highly efficient microfluidic sample preconcentration device based on the electrokinetic trapping mechanism enabled by nanofluidic filters. The device, fabricated by standard photolithography and etching techniques, generates an extended space charge region within a microchannel, which was used to both collect and trap the molecules efficiently. The electrokinetic trapping and collection can be maintained for several hours, and concentration factors as high as 10(6)-10(8) have been demonstrated. This device could be useful in various bioanalysis microsystems, due to its simplicity, performance, robustness, and integrabilty to other separation and detection systems.