title: Free-flow zone electrophoresis of peptides and proteins in PDMS microchip for narrow pI range sample prefractionation coupled with mass spectrometry.
abstract: In this paper, we are evaluating the strategy of sorting peptides/proteins based on the charge to mass without resorting to ampholytes and/or isoelectric focusing, using a single- and two-step free-flow zone electrophoresis. We developed a simple fabrication method to create a salt bridge for free-flow zone electrophoresis in PDMS chips by surface printing a hydrophobic layer on a glass substrate. Since the surface-printed hydrophobic layer prevents plasma bonding between the PDMS chip and the substrate, an electrical junction gap can be created for free-flow zone electrophoresis. With this device, we demonstrated a separation of positive and negative peptides and proteins at a given pH in standard buffer systems and validated the sorting result with LC/MS. Furthermore, we coupled two sorting steps via off-chip titration and isolated peptides within specific pI ranges from sample mixtures, where the pI range was simply set by the pH values of the buffer solutions. This free-flow zone electrophoresis sorting device, with its simplicity of fabrication, and a sorting resolution of 0.5 pH unit, can potentially be a high-throughput sample fractionation tool for targeted proteomics using LC/MS.
authors.affiliation: Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, USA.
authors.forename: Yong-Ak
authors.initials: YA
authors.lastname: Song
authors.forename: Michael
authors.initials: M
authors.lastname: Chan
authors.forename: Chris
authors.initials: C
authors.lastname: Celio
authors.forename: Steven R
authors.initials: SR
authors.lastname: Tannenbaum
authors.forename: John S
authors.initials: JS
authors.lastname: Wishnok
authors.forename: Jongyoon
authors.initials: J
authors.lastname: Han
mesh_terms: D000818:Animals; D002417:Cattle; D004129:Dimethylpolysiloxanes / Q000737:chemistry; D004586:Electrophoresis / Q000295:instrumentation*; D004867:Equipment Design; D006736:Horses; D007525:Isoelectric Focusing / Q000295:instrumentation*; D013058:Mass Spectrometry / Q000379:methods*; D044085:Microfluidics / Q000295:instrumentation*; D010455:Peptides / Q000302:isolation & purification*; D011506:Proteins / Q000302:isolation & purification*; D013499:Surface Properties
chemical_list: D004129:Dimethylpolysiloxanes; D010455:Peptides; D011506:Proteins; C013830:baysilon