Thin-layer matrix sublimation with vapor-sorption induced co-crystallization for sensitive and reproducible SAMDI-TOF MS analysis of protein biosensors

Michael J. Roth, Jaekuk Kim, Erica M. Maresh, Daniel A. Plymire, John R. Corbett, Junmei Zhang, Steven M. Patrie

Research output: Contribution to journalArticlepeer-review

10 Scopus citations

Abstract

Coupling immunoassays on self-assembled monolayers (SAMs) to matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry (MS) provides improved assay selectivity compared with traditional photometric detection techniques. We show that thin-layer-transfer (TLT) of α-cyano-4-hydroxycinnaminic acid (CHCA) MALDI matrix via vacuum sublimation followed by organic solvent-based vapor-sorption induced co-crystallization (VIC) results in unique matrix/analyte co-crystallization tendencies that optimizes assay reproducibility and sensitivity. Unique matrix crystal morphologies resulted from VIC solvent vapors, indicating nucleation and crystal growth characteristics depend upon VIC parameters. We observed that CHCA microcrystals generated by methanol VIC resulted in >10× better sensitivity, increased analyte charging, and improved precision compared with dried droplet measurements. The uniformity of matrix/analyte co-crystallization across planar immunoassays directed at intact proteins yielded low spectral variation for single shot replicates (18.5 % relative standard deviation, RSD) and signal averaged spectra (<10 % RSD). We envision that TLT and VIC for MALDI-TOF will enable high-throughput, reproducible array-based immunoassays for protein molecular diagnostic assays in diverse biochemical and clinical applications.

Original languageEnglish (US)
Pages (from-to)1661-1669
Number of pages9
JournalJournal of the American Society for Mass Spectrometry
Volume23
Issue number10
DOIs
StatePublished - Oct 2012

Keywords

  • MALDI
  • Protein analysis
  • Reproducibility
  • SAMDI

ASJC Scopus subject areas

  • Structural Biology
  • Spectroscopy

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