Development of a Matrix-prespotted Plate for Enhancing the Reproducibility of Serum Glycan Analysis by MALDI-TOF-MS

Abstract

Matrix Assisted Laser Desorption/Ionization-Time-of-Flight mass spectrometry (MALDI-TOF-MS) is the most widely used MS technique for glycan analysis. However, the poor point-to-point and sample-to-sample reproducibility becomes a limit in glycan biomarker research. A prespotted MALDI plate which overcomes the large crystal formation of 2,5-dihydroxybenzoic acid (DHB) has been developed and applied for glycan analysis. A homogeneous matrix coated surface without a crystal structure was formed on a hydrophilic/ hydrophobic patterned surface using a piezoelectric device. The reproducible MALDI-TOF-MS data have been presented using MALDI imaging of beer glycan as well as serum glycan eluted from 10% and 20% ACN elution fractions. The glycan profile from the serum glycan by MALDI-TOF-MS with a DHB prespotted plate was highly conserved for 10 different spectra and the coefficient of variations of significant ion peaks of MALDI data varies from 3.59 to 19.95.

Acquisition of the depth profiles and reproducible mass spectra in matrix‐assisted laser desorption/ionization of inhomogeneous samples

“…We also prepared samples with a micro‐spotter (μMatrix Spotter, ASTA, Suwon, Korea) . Both CHCA and 2,5‐dihydroxybenzoic acid (DHB) were used as the matrix.…”

“…We also prepared samples with a micro-spotter (μMatrix Spotter, ASTA, Suwon, Korea). [24] Both CHCA and 2,5dihydroxybenzoic acid (DHB) were used as the matrix. To prepare the DHB samples, an amount of 3 pL per drops of a solution (20% methanol and 0.1% TFA in water) containing DHB and an analyte was piezoelectrically sprayed.…”

On-target and nanoparticle-facilitated selective enrichment of peptides and proteins for analysis by MALDI-MS

“…ZipTip from Millipore) and are used primarily for desalting peptides and for selective enrichment of ionic peptides from low ionic strength solutions. Hydrophobic targets for desalting peptides as well as hydrophobic targets with hydrophilic anchors have been prepared by (i) photopatterning a self‐assembled monolayers (SAMs) on gold with small hydrophilic spots and concentric larger medium hydrophobicity spots arrayed on a superhydrophobic target (Mass Spec Focus Desalting Chip from Qiagen) , (ii) atmospheric molding of poly(alkyl methacrylate co‐methyl methacrylate) copolymers , (iii) templating poly(methyl methacrylate) (PMMA) and PMMA derivatized with fullerence‐C 60 on SS targets , (iv) patterning small PMMA spots on larger concentric silica spots arrayed on a silicon substrate modified with a fluorine‐terminated silane , (v) photolithography and chemical etching of a silicon substrate , and (vi) patterning concentric hydrophobic, hydrophilic, and hydrophobic spots on a silicon substrate . Similarly, ionic targets suitable for electrostatic retention of anionic and cationic peptides have been prepared by atmospheric molding of ionic copolymers with carboxy, sulfo, dimethylalkylamino, and trimethylalkylammonium groups , and photopatterning SAMs on gold with small hydrophilic spots and concentric larger weak cation exchange spots arrayed on a superhydrophobic target (Mass Spec Focus Chip from Qiagen) .…”

Analysis of carbohydrates and glycoconjugates by matrix‐assisted laser desorption/ionization mass spectrometry: An update for 2011–2012

“…A pre-spotted MALDI plate, which overcomes the problem of the large crystal formation from DHB, has been developed by Ha et al (2011a). A homogeneous matrix-coated surface without a crystal structure was formed on a hydrophilic/hydrophobic patterned surface with 1700 mm spots using a piezoelectric device with 5760 Â 1440 dpi resolution and a six channel piezoelectric head that delivered 87 pl per 200 mm 2 .…”