AVS 53rd International Symposium
    Biomaterial Interfaces Tuesday Sessions
       Session BI-TuP

Paper BI-TuP18
Gradient Functionalized Plasma Polymer Films for on Probe Affinity Capture (OPAC) MALDI MS

Tuesday, November 14, 2006, 6:00 pm, Room 3rd Floor Lobby

Session: Biomaterial Interfaces Poster Session
Presenter: C.J. Mathai, Southern Illinois University
Authors: C.J. Mathai, Southern Illinois University
M.Z. Segu, Southern Illinois University
R.G. Kinsel, Southern Illinois University
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Surface modification of the sample targets used for Matrix Assisted Laser Desorption / Ionization (MALDI) Mass Spectrometry (MS) is receiving considerable attention because these devices allow for rapid, on-probe fractionation of complex protein mixtures. This on-MALDI-probe fractionation of proteins/peptides is now being explored as a novel approach for disease diagnosis. Our research has focused on the use of rf pulsed plasma technique for incorporation of the surface chemical functionality on the MALDI target. In the present study a new rf plasma reactor design is described which allows for rapid deposition of discreet, or continuous, gradients of chemical functionality directly on a MALDI target. The reactor system has a cylindrical chamber with two adjustable electrodes kept parallel to each other. One of the electrodes is powered by 13.56 MHz rf generated by a function generator and amplified by an rf power amplifier. A matching network is used to couple the rf power to the electrode. For pulsed operational mode, a signal generator is employed to pulse the function generator. By varying the pulsing parameters, plasma on and off times can be varied to achieve maximum control on the film chemistry. Patterned and gradient plasma polymer films are obtained by mounting MALDI probes on an automated XY stage with specially designed masks. The complete coating system including the XY stage is fully controlled by using LabView software. Using this system, plasma polymer thin films having gradient hydrophobicity or acidity are depositied directly on the MALDI probe as a series of discreet spots. All surface chemical modifications are fully characterized by FT-IR and contact angel measurement. Subsequently, these gradient surface modified MALDI probes are used to perform on-probe fractionation of various mixtures of peptides and proteins with a goal of identifying optimal conditions for fractionation and analysis of the peptide/protein mixture constituents.