Solid-phase extraction/MALDI-MS: extended ion-pairing surfaces for the on-target cleanup of protein samples

Area of Science:

• Analytical Chemistry
• Biochemistry
• Materials Science

Background:

• Matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) is a powerful analytical technique.
• Current MALDI-MS targets modified for solid-phase extraction (SPE) have limited binding capacity due to self-assembled monolayers (SAMs).
• This limitation hinders the analysis of complex or contaminated samples.

Purpose of the Study:

• To develop novel SPE/MALDI-MS surfaces with significantly higher binding capacity.
• To overcome the low binding capacity of SAM-based SPE/MALDI-MS targets.
• To improve the cleanup of analytes from challenging sample matrices.

Main Methods:

• Covalent modification of MALDI-MS target surfaces.
• Attachment of high molecular weight polylysine chains (> 300,000) to target surfaces.
• Evaluation of binding capacity and analyte capture efficiency using peptide/protein solutions.

Main Results:

• Polylysine-modified targets exhibit approximately 100 times the binding capacity of SAM-based targets.
• These new targets effectively bind peptides/proteins via ion-pairing interactions.
• Over 60% of protein can be captured from highly contaminated solutions.

Conclusions:

• Polylysine SPE/MALDI-MS targets provide a practical solution for analyzing small volumes of contaminated peptide/protein samples.
• Enhanced binding capacity allows for efficient cleanup of analytes from salts, buffers, detergents, and chaotropic agents.
• This advancement facilitates MALDI-MS analysis of complex biological samples.