title: Electrospray interfacing of polymer microfluidics to MALDI-MS.
abstract: The off-line coupling of polymer microfluidics to MALDI-MS is presented using electrospray deposition. Using polycarbonate microfluidic chips with integrated hydrophobic membrane electrospray tips, peptides and proteins are deposited onto a stainless steel target followed by MALDI-MS analysis. Microchip electrospray deposition is found to yield excellent spatial control and homogeneity of deposited peptide spots, and significantly improved MALDI-MS spectral reproducibility compared to traditional target preparation methods. A detection limit of 3.5 fmol is demonstrated for angiotensin. Furthermore, multiple electrospray tips on a single chip provide the ability to simultaneously elute parallel sample streams onto a MALDI target for high-throughput multiplexed analysis. Using a three-element electrospray tip array with 150 microm spacing, the simultaneous deposition of bradykinin, fibrinopeptide, and angiotensin is achieved with no cross talk between deposited samples. In addition, in-line proteolytic digestion of intact proteins is successfully achieved during the electrospray process by binding trypsin within the electrospray membrane, eliminating the need for on-probe digestion prior to MALDI-MS. The technology offers promise for a range of microfluidic platforms designed for high-throughput multiplexed proteomic analyses in which simultaneous on-chip separations require an effective interface to MS.
authors.affiliation: Department of Mechanical Engineering, and Bioengineering Program, University of Maryland, College Park, MD 20742, USA.
authors.forename: Ying-Xin
authors.initials: YX
authors.lastname: Wang
authors.forename: Yi
authors.initials: Y
authors.lastname: Zhou
authors.forename: Brian M
authors.initials: BM
authors.lastname: Balgley
authors.forename: Jon W
authors.initials: JW
authors.lastname: Cooper
authors.forename: Cheng S
authors.initials: CS
authors.lastname: Lee
authors.forename: Don L
authors.initials: DL
authors.lastname: DeVoe
mesh_terms: D046210:Microfluidic Analytical Techniques / Q000295:instrumentation*; D010455:Peptides / Q000032:analysis*; D011108:Polymers / Q000737:chemistry; D011506:Proteins / Q000032:analysis*; D021241:Spectrometry, Mass, Electrospray Ionization; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
chemical_list: D010455:Peptides; D011108:Polymers; D011506:Proteins