Carbon Nanoparticles and Graphene Nanosheets as MALDI Matrices in Glycomics: a New Approach to Improve Glycan Profiling in Biological Samples

Abstract

Glycomics continues to be a highly dynamic and interesting research area due to the need to comprehensively understand the biological attributes of glycosylation in many important biological functions such as the immune response, cell development, cell differentiation/adhesion, and host-pathogen interactions. Although matrix-assisted laser desorption ionization (MALDI) mass spectrometry (MS) has proven to be suitable for glycomic profiling studies, there is a need for improved sensitivity in the detection of native glycans, which ionize inefficiently. In this study, we investigated the efficiencies of graphene nanosheets (GNs) and carbon nanoparticles (CNPs) as MALDI matrices and co-matrices in glycan profiling. Our results indicated an enhancement of signal intensity by several orders of magnitude upon using GNs and CNPs in MALDI analysis of N-glycans derived from a variety of biological samples. Interestingly, increasing the amounts of CNPs and GNs improved not only the signal intensities but also prompted in-source decay (ISD) fragmentations, which produced extensive glycosidic and cross-ring cleavages. Our results indicated that the extent of ISD fragmentation could be modulated by CNP and GN concentrations, to obtain MS and pseudo-MS spectra. The results for glycan profiling in high salt solutions confirmed high salt-tolerance capacities for both CNPs and GNs. Finally, the results showed that by using CNPs and GNs as co-matrices, DHB crystal formation was more homogeneous which improved shot-to-shot reproducibility and sensitivity. Graphical Abstract ᅟ.

Magnetic carbon nanocomposites as a MALDI co-matrix enhancing MS-based glycomics

“…S1b) indicated that CNPs@Fe 3 O 4 NCs have a broad absorption peak from 250 nm to 375 nm which corresponds to a π−π* transition of aromatic sp 2 carbon domains. As it was shown in our previous work [26], Raman spectra also confirmed π-conjugation structures of CNPs. Comparing CNPs and Fe 3 O 4 NPs, the UV−Vis data verified higher molar absorptivity of CNPs@Fe 3 O 4 NCs, at the MALDI laser radiation wavelength (355 nm).…”

“…1a), resulting in poor shot-to-shot reproducibility in MALDI analyses [26, 39, 40]. Although crystallization could be improved via recrystallization using methanol, still small crystals formed near the rim (Fig.…”

“…Our previous report [26] on CNPs and GNs, demonstrated that the degree of ISD could be controlled when when such material are used as co-matrices. In order to evaluate the performance of CNPs@Fe 3 O 4 NCs as a co-matrix, MALDI-TOF-MS spectrum of RNase B glycans was obtained using DHB+CNPs@Fe 3 O 4 NCs (Fig.…”

“…When applied as MALDI matrices, carbon nanomaterials like graphene nanosheets, carbon nanodots, and carbon nanotubes have shown to be quite effective because of their notable electrical properties, optical absorption, and minimal background interference [20–26]. In addition to carbon-based nanomaterials, some other nanomaterials have also been used as MALDI matrices.…”

“…Recently, we investigate the advantages of using graphene nanosheets (GNs) and carbon nanoparticles (CNPs) as MALDI matrices and co-matrices in glycan profiling [26]. The modulation of CNPs and GNs concentrations significantly enhanced glycan signal intensity by several orders of magnitude, and controlled the degree of in-source decay (ISD) fragmentation [26].…”