Authors: A. Hieke
Affilation: Stanford University, School of Medicine, United States
Pages: 93 - 96
Keywords: MALDI, ionization, biomarker, molecular diagnostics, surface
Imperfections of the MALDI ionization process of proteins and peptides impose considerable limitations on the utility of mass spectrometry in basic life sciences and ultimately on the application in biomarker discovery and medical diagnostics. Improved understanding of and control over the MALDI ionization process therefore holds the potential to largely expand the performance of mass spectrometry. MALDI ion yield is extremely low, typically 1E-5 to 1E-6 and a detailed explanation of the MALDI mechanism remains elusive. Current models do also not take into account the chemical composition of the MALDI surface. Presented here is a MALDI-TOF mass spectrometric study using 21 different metals, ceramics, and plastics as surfaces combined with a tryptic digest of BSA and an artificial protein mix as samples. We observed 3 orders of magnitude variation in ion yield with Gold and Aluminum providing best results. Remarkably, there is no clear correlation between the observed ion yield and any of the considered individual physical properties. This investigation illustrates the notoriously low sensitivity of MALDI and it is unlikely that this problem can be corrected by solely by optimized surface materials. Fundamentally novel solutions are required to solve the problem of low ionization efficiency of MALDI.
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