An Aptameric Microfluidic System for Specific Purification, Enrichment, and Mass Spectrometric Detection of Biomolecules

We present an innovative microfluidic system that accomplishes specific capture, enrichment, and isocratic elution of biomolecular analytes with coupling to label-free mass spectrometric detection. Analytes in a liquid phase are specifically captured and enriched via their affinity binding to aptamers, which are immobilized on microbeads packed inside a microchamber. Exploiting thermally induced reversible disruption of aptamer-analyte binding via on-chip temperature control with an integrated heater and temperature sensor, the captured analytes are released into the liquid phase and then isocratically eluted and transferred via a microfluidic flow gate for detection by matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS). The utility of the device is demonstrated using adenosine monophosphate (AMP) as a model analyte. Experimental results indicate that the device is capable of purifying and enriching the analyte from a sample mixed with nonspecific analytes and contaminated with salts. In addition, thermally induced analyte release is performed at modest temperatures (45degC), and mass spectra obtained from MALDI-MS demonstrate successful detection of AMP at concentrations as low as 10 nM following enrichment by consecutive infusion of a diluted sample.