Matrix enrichment by black phosphorus improves ionization and reproducibility of mass spectrometry of intact cells, peptides, and amino acids

Abstract

Intact (whole) cell matrix-assisted laser desorption/ionization mass spectrometry (MALDI-TOF MS) is an established method for biotyping in clinical microbiology as well as for revealing phenotypic shifts in cultured eukaryotic cells. Intact cell MALDI-TOF MS has recently been introduced as a quality control tool for long-term cultures of pluripotent stem cells. Despite the potential this method holds for revealing minute changes in cells, there is still a need for improving the ionization efficiency or peak reproducibility. Here we report for the first time that supplementation by fine particles of black phosphorus to the standard MALDI matrices, such as sinapinic and α-cyano-4-hydroxycinnamic acids enhance intensities of mass spectra of particular amino acids and peptides, presumably by interactions with aromatic groups within the molecules. In addition, the particles of black phosphorus induce the formation of small and regularly dispersed crystals of sinapinic acid and α-cyano-4-hydroxycinnamic acid with the analyte on a steel MALDI target plate. Patterns of mass spectra recorded from intact cells using black phosphorus-enriched matrix were more reproducible and contained peaks of higher intensities when compared to matrix without black phosphorus supplementation. In summary, enrichment of common organic matrices by black phosphorus can improve discrimination data analysis by enhancing peak intensity and reproducibility of mass spectra acquired from intact cells.

Silver Nanostructured Substrates in LDI-MS of Low Molecular Weight Compounds

“…Interactions of the analytes with nanostructured substrates may affect LDI-MS efficiency, and they can be characterized by complementary analytical techniques. A good example of such work was reported by Mandal et al [26].…”

Molecular-level degradation pathways of black phosphorus revealed by mass spectrometry fingerprinting

“…BP has been used as a matrix in LDI-MS for detection of various compounds. 20,21 It has also been reported that elemental phosphorus itself can generate phosphorus clusters under laser ablation. [22][23][24][25] This inspired us to use LDI-MS to resolve the puzzle of the BP degradation mechanism.…”