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Integration of Protein Processing Steps on a Droplet Microfluidics Platform for MALDI-MS Analysis
journal contribution
posted on 2010-03-01, 00:00 authored by Debalina Chatterjee, A. Jimmy Ytterberg, Sang Uk Son, Joseph A. Loo, Robin L. GarrellA droplet-based (digital) microfluidics platform has been developed to prepare and purify protein samples for measurement by matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS). Liquid droplets are moved in air by sequentially applying an electric potential to an array of electrodes patterned beneath a hydrophobic dielectric layer. We show that a complete integrated sequence of protein processing steps can be performed on this platform, including disulfide reduction, alkylation, and enzymatic digestion, followed by cocrystallization with a MALDI matrix and analysis of the sample in situ by MALDI-MS. Proteins carbonic anhydrase, cytochrome c, and ubiquitin were used to demonstrate the digestion and postdigestion steps; insulin, serum albumin, and lysozyme were used to illustrate the complete sequence of protein processing steps available with the platform. Several functional improvements in the platform are reported, notably, the incorporation of acetonitrile in the protein droplets to facilitate movement, and patterning the device surfaces to optimize sample crystallization. The method is fast, simple, repeatable, and results in lower reagent consumption and sample loss than conventional techniques for proteomics sample preparation.
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MALDI matrixProtein Processing StepsLiquid dropletsDroplet Microfluidics Platformproteins carbonic anhydrasepostdigestion stepssequencemicrofluidics platformdisulfide reductionprotein processing stepsprotein samplesreagent consumptionsample losssample crystallizationprotein dropletsproteomics sample preparationdielectric layerdevice surfacescytochrome cserum albumin
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