Detergent enhancement of on‐tissue protein analysis by matrix‐assisted laser desorption/ionization imaging mass spectrometry

Abstract

Matrix-Assisted Laser Desorption/Ionization (MALDI) Imaging Mass Spectrometry (IMS) is a molecular technology that allows simultaneous investigation of the content and spatial distribution of molecules within tissue. In this work, we examine different classes of detergents, the anionic sodium dodecyl sulfate (SDS), the nonionic detergents Triton X-100, Tween 20 and Tween 80, and the zwitterionic 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate (CHAPS) for use in MALDI IMS of analytes above m/z 4000. These detergents were found to be compatible with MALDI MS and did not cause signal suppression relative to non-detergent applications and did not produce interfering background signals. In general, these detergents enhanced signal acquisition within the mass range m/z 4–40 000. Adding detergents into the matrix was comparable with the separate application of detergent and matrix. Evaluation of spectra collected from organ-specific regions of a whole mouse pup section showed that different detergents perform optimally with different organs, indicating that detergent selection should be optimized on the specific tissue for maximum gain. These data show the utility of detergents towards enhancement of protein signals for on-tissue MALDI IMS analysis.

Tissue protein imaging at 1 μm laser spot diameter for high spatial resolution and high imaging speed using transmission geometry MALDI TOF MS

“…The energetic electrons strike the scintillator, and because the light output from the scintillator is proportional to the energy lost to electronic collisions, high isolation voltages translate into intense flashes of light at the output. The PMT detects these flashes of light, amplifies and produces a high current output pulse at ground potential regardless of the voltage setting at the front of the detector [11]. Operating the MCP at low voltage and taking advantage of the high output current of the PMT high gain and dynamic range, saturation effects of highly abundant low mass ions are minimized.…”

Localized in Situ Hydrogel-Mediated Protein Digestion and Extraction Technique for on-Tissue Analysis

“…Recent advances in the field have focused on improved sensitivity of targeted chemical classes and achieving high spatial resolution IMS. 6, 7 Concurrent to these developments, the field has addressed challenging clinical and biological applications. 8–11 …”

Current frontiers in clinical research application of MALDI imaging mass spectrometry

“…For protein analysis, the most common washing procedure applied for MALDI-IMS of proteins is a fixation procedure in increasing concentrations of ethanol (1 min in each of 70% EtOH and 100% EtOH). In addition to this, different protocols have been proposed for efficient analysis of proteins and peptides using organic solvents [32], buffers [33] or detergents [34].…”