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

Abstract

More than 50% of all known proteins are glycosylated, which is critical for many biological processes such as protein folding and signal transduction. Glycosylation has proven to be associated with different mammalian diseases such as breast and liver cancers. Therefore, characterization of glycans is highly important to facilitate a better understanding of the development and progression of many human diseases. Although matrix-assisted laser desorption ionization-mass spectrometry (MALDI-MS) offers several advantages such as ease of operation and short analysis times, however, due to the complexity of glycan structures and their low ionization efficiency, there are still challenges that need to be addressed to achieve sensitive glycan analysis. Here, magnetic carbon nanocomposites (CNPs@FeO NCs) were used as a new MALDI matrix or co-matrix for the analysis of glycans derived from different model glycoproteins and human blood serum samples. The addition of CNPs@FeO NCs to the matrix significantly enhanced glycan signal intensity by several orders of magnitude, and effectively controlled/reduced/eliminated in-source decay (ISD) fragmentation. The latter was attained by modulating CNPs@FeO NCs concentrations and allowed the simultaneous study of intact and fragmented glycans, and pseudo-MS analysis. Moreover, CNPs@FeO NCs was also effectively employed to desalt samples directly on MALDI plate, thus enabling direct MALDI-MS analysis of unpurified permethylated glycans derived from both model glycoproteins and biological samples. On-plate desalting enhanced sensitivity by reducing sample loss. Graphical abstract ᅟ.

Characterization of glycan isomers using magnetic carbon nanoparticles as a MALDI co-matrix

“…We recently investigated the performance of using MCNPs as a MALDI matrix and co-matrix in glycan profiling 61. MCNPs not only enhanced the signal intensities by several orders of magnitude but also prompted ISD fragmentations, which produced extensive glycosidic and cross-ring cleavages.…”

“…HPLC grade ethanol, acetonitrile (ACN), and water were used for sample preparation and were purchased from Sigma-Aldrich (St. Louis, MO). MCNPs were readily synthesized by mixing CNPs, FeCl 3 ·6H 2 O, and FeCl 2 ·4H 2 O at 50 °C under N 2 atmosphere, as per our recently published paper 61…”

“…Recently, we investigated the performance of CNPs, GNs, and magnetic CNPs (MCNPs) as MALDI matrices or co-matrices for glycan profiling of different model glycoproteins and human blood serum samples 50,61. The material showed excellent absorption and transfer of laser energy to glycans, resulting in improved signal intensities by several orders of magnitude.…”

“…49 In recent years, the importance of nanomaterials as outstanding MALDI matrices has become increasingly evident due to their unique physicochemical characteristics, such as excellent optical absorption, exceptional electrical properties, and low background interference. [50][51][52][53][54][55][56][57] Among these materials, carbon-based nanomaterials such as carbon nanotubes, 58 carbon nanodots, 59,60 carbon nanoparticles (CNPs), 50,61 and graphene nanosheets (GNs) 50,62,63 have attracted the most attention. Compared to traditional organic matrices, these nanomaterials facilitate the desorption process and enhance MS signal intensity due to their superior interaction with biomolecules and efficient energy absorption.…”

“…Recently, we investigated the performance of CNPs, GNs, and magnetic CNPs (MCNPs) as MALDI matrices or co-matrices for glycan proling of different model glycoproteins and human blood serum samples. 50,61 The material showed excellent absorption and transfer of laser energy to glycans, resulting in improved signal intensities by several orders of magnitude. Extensively-producing glycosidic and cross-ring cleavages, with the ability to easily control the extent of ISD fragmentation by changing the amount of nanomaterials in MALDI spot, conrmed the capability of these materials in the structural study of glycans.…”