AVS 53rd International Symposium
    Applied Surface Science Wednesday Sessions
       Session AS-WeM

Paper AS-WeM12
Combining Fluidics, Surface Chemistries and Direct Mass Spectrometric Detection to Address Protein Analyte Quantitation from Complex Samples for the Purpose of Diagnostic Assays

Wednesday, November 15, 2006, 11:40 am, Room 2005

Session: Molecular Ion Sources and Characterization of Biomaterials
Presenter: L.O. Lomas, Ciphergen
Authors: L.O. Lomas, Ciphergen
E. Fung, Ciphergen
E. Boschetti, Ciphergen
Correspondent: Click to Email
The development of analyte assays for the purpose of diagnostic tests is driven by multiple factors, including sample availability, required throughput and quantitative reproducibility. Although antibody-based assays have dominated in the detection of peptide/protein analytes and serve well in terms of throughput and quantitative reproducibility, mass spectrometry is becoming more main-stream due to the added information provided in terms of precise analyte conformation by mass and/or secondary structure fragmentation. Laser Desorption/ionization mass spectrometry (MS) is particularly well suited for both peptide and protein characterization, however, absolute quantitation has been elusive due to complexities associated with integrating sample processing and final analyte detection. To resolve these issues, we have integrated unique solid-phase extractions chemistries directly on MS probes that allow us to quantitatively extract the protein analytes of interest from a complex sample in a defined and controlled process. The resulting analyte arrays minimize the sample requirements and allow for high-throughput processing using standard sample fluidic systems. To exemplify this process, we describe the development of a seven protein-marker panel that may aid in the stratification of women with a pelvic mass. The specific MS-based analyte array assays permit the discrimination of post-translationally modified forms of the markers and by using reference standards, we are able to achieve absolute quantitation with high reproducibility (CV<10%). The integrated assay platform includes an automated liquid handler, analyte-specific arrays, and a MS reader. Measurements of the seven markers provide a measure of the risk that a pelvic mass is malignant. Women at low risk for ovarian cancer can be further evaluated by their general gynecologist, while women at high risk for ovarian cancer should be evaluated by a specialist gynecologic oncologist.