(5h) A Microfluidic Platform for Enhancing Quantitation of Biological Mixtures

In any analytical method of biomarker identification, great lengths must be made to extract or purify specific molecules prior to instrumental detection. In the case of proteomic analysis of a cell lysate via mass spectrometry, for example, counter ions (DNA) and neutral molecules (lipids and triglycerides) can inhibit signal and increase systematic noise, increasing the limit of detection. The signal inhibition is likely caused by the electrostatic coupling of the proteins/peptides with anions (DNA) or micelle formation with non-polar molecules (lipids). Using a microfluidic device with integrated electrodes, we have explored and optimized methods to create enriched biomolecule fractions for such proteomic analyses based on the Electric Field Flow Fractionation (EFFF) technique. With a simple mixture of DNA and peptide, we have demonstrated that over 95% of the peptide can be separated from the DNA with a molecular throughput of about 1.2x10-9 mol/min. Further, we have observed an improvement in the limit of detection for peptides by nearly an order of magnitude when these anionic components (DNA) are removed from the sample using the reported microfluidic charge-induced lateral separation platform integrated to an electrospray ionization source (ESI-MS). Currently, we are evaluating the performance of this microfluidic device as a sample preparation unit for improving the inline quantitation of various biological mixtures.