3D ToF-SIMS Analysis of Peptide Incorporation into MALDI Matrix Crystals with Sub-micrometer Resolution

Abstract

Abstract. The analytical sensitivity in matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) is largely affected by the specific analyte-matrix interaction, in particular by the possible incorporation of the analytes into crystalline MALDI matrices. Here we used time-of-flight secondary ion mass spectrometry (ToF-SIMS) to visualize the incorporation of three peptides with different hydrophobicities, bradykinin, Substance P, and vasopressin, into two classic MALDI matrices, 2,5-dihydroxybenzoic acid (DHB) and α-cyano-4-hydroxycinnamic acid (HCCA). For depth profiling, an Ar cluster ion beam was used to gradually sputter through the matrix crystals without causing significant degradation of matrix or biomolecules. A pulsed Bi 3 ion cluster beam was used to image the lateral analyte distribution in the center of the sputter crater. Using this dual beam technique, the 3D distribution of the analytes and spatial segregation effects within the matrix crystals were imaged with sub-μm resolution. The technique could in the future enable matrix-enhanced (ME)-ToF-SIMS imaging of peptides in tissue slices at ultra-high resolution.

The electrospinning of a thermo-responsive polymer with peptide conjugates for phenotype support and extracellular matrix production of therapeutically relevant mammalian cells

“…2A). Nor-GGG-YIGSR peptide positive ion fragment signals were identified and were corroborated to literature 30,31 (see fragment structures of identified signals in Fig. S23 †).…”

Mass Spectrometry Imaging: A Review of Emerging Advancements and Future Insights

“…Interestingly, alternative ionization methods (e.g., SIMS) have been used to characterize the analyte incorporation into spots and, although difficult to implement, similar imaging-based studies would be interesting. 25 Homogenous application has also been a major focus, and researchers have utilized alternative application methods to improve this facet in the past few years. One example is electrospray deposition, for which units tend to be home-built.…”

Amorphous Conjugated Polymers as Efficient Dual‐Mode MALDI Matrices for Low‐Molecular‐Weight Analytes

“…During the preparation of the MALDI sample, SOMs incorporate the analyte into their crystal lattice, and ideally, a homogenous and defect free crystal lattice is targeted to ensure a high ionization efficiency and successful measurements, and the correlation between the matrix crystal forms and the analyte signal distribution was intensively studied . Crystal formation and analyte incorporation are influenced by the sample preparation method and several method related parameters; e. g. it was reported that the commonly used air‐dried‐droplet method leads to poor homogeneity, while electrospray sample preparation gives evenly sized matrix crystals with well‐distributed analyte incorporation . Furthermore, a low vapor pressure of the used solvent and a longer drying time improves the crystal formation and promotes homogeneous incorporation of the analyte .…”