Researchers from the Czech Republic have developed a technology that facilitates the preparation of matrix-assisted laser desorption/ionization (MALDI) – compatible protein chips by a process termed ambient ion landing.
The team, comprising scientists from the Czech Academy of Sciences (Prague, Czech Republic), Charles University (Prague, Czech Republic), Purkyne University (Usti nad Labem, Czech Republic) described this new technology in a recent issue of Analytical Chemistry.
MALDI is a technique that enables analysis of biomolecules and large organic molecules – molecules that are sensitive to conventional ionization methods. The ionization technique is used in mass spectrometry.
Prepared using ambient ion landing, the novel compatible proteins were electrosprayed and immobilized on nonreactive dry metal and metal oxide surfaces.
Compared with other substances, this nonreactive surface demonstrated the least interactions with the samples under investigation.
Under atmospheric pressure, the team used an automated ion landing apparatus that enabled ion landing of the electrosprayed protein molecules. This process allowed for the creation of protein chips with an established range of sample positions.
Protein chips primed in this way were shown to be fully compatible with MALDI ionization and thus these MALDI-compatible protein chips could be used for the development of bioanalytical assays.
The assays function via the interaction between a stationary protein and sampled analyte directly on the protein chip – an interaction that is then analyzed in situ by MALDI MS.
The team demonstrated three different bioanalytical applications of the protein chips.
One of the protein chips with immobilized proteolytic enzymes showed the convenience of the chips for fast in situ peptide MALDI sequencing. Another protein chip based on lectin demonstrated the capacity to enhance glycopeptides from complex mixtures followed by MALDI analysis.
A third chip with immobilized antibodies was utilized for a new immunoMALDI workflow allowing antigen enrichment followed by highly specific MALDI detection.
The new technology will could numerous bioanalytical applications, particularly in the development of bioanalytical assays.
Source: Pompach P, Benada O, Rosulek M et al. Protein chips compatible with MALDI Mass Spectrometry prepared by Ambient Ion Landing. Analytical Chemistry doi: 10.1021/acs.analchem.6b01366 (2016).