title: Simple fabrication of hydrophobic surface target for increased sensitivity and homogeneity in matrix-assisted laser desorption/ionization time-of-flight mass spectrometry analysis of peptides, phosphopeptides, carbohydrates and proteins.
abstract: To enhance sample signals and improve homogeneity in matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF) analysis, a simple, rapid, and efficient sample preparation method was developed in this study. Polydimethylsiloxane (PDMS) was coated on a stainless steel MALDI plate, forming a transparent, hydrophobic surface that enhanced sample signals without producing observable background signals. Compared to the use of an unmodified commercial metal MALDI plate, peptide signals were enhanced by ~7.1-11.0-fold due to the reduced sample spot area of the PDMS-coated plate, and showed improved peptide mass fingerprinting (PMF) and MS/MS peptide sequencing results. In the analysis of phosphopeptides and carbohydrates with a 2,5-dihydroxybenzoic acid (DHB) matrix, the PDMS-coated plate showed improved sample homogeneity and signal enhancements of ~5.2-8.2-fold and ~2.8-3.2-fold, respectively. Improved sensitivity in the observation of more unique fragment ions by MS/MS analysis, to successfully distinguish isomeric carbohydrates, was also illustrated. In protein analysis with a sinapinic acid (SA) matrix, a ~3.4-fold signal enhancement was observed. The PDMS film coating was easily removed and refabricated to avoid sample carryover, and was applicable to diverse commercial MALDI plates. The PDMS-coated approach is a simple, practical, and attractive method for enhancing analyte signals and homogeneity.
authors.affiliation: Graduate Institute of Integrated Medicine, China Medical University, Taichung, Taiwan. cjchen@mail.cmu.edu.tw
authors.forename: Chao-Jung
authors.initials: CJ
authors.lastname: Chen
authors.forename: Chien-Chen
authors.initials: CC
authors.lastname: Lai
authors.forename: Mei-Chun
authors.initials: MC
authors.lastname: Tseng
authors.forename: Yu-Ching
authors.initials: YC
authors.lastname: Liu
authors.forename: Shih-Yi
authors.initials: SY
authors.lastname: Lin
authors.forename: Fuu-Jen
authors.initials: FJ
authors.lastname: Tsai
mesh_terms: D002241:Carbohydrates / Q000032:analysis*; D002623:Chemistry Techniques, Analytical / Q000379:methods*; D004591:Electrophoresis, Polyacrylamide Gel; D005841:Gentisates / Q000737:chemistry; D057927:Hydrophobic and Hydrophilic Interactions; D007834:Lasers; D057230:Limit of Detection; D010455:Peptides / Q000032:analysis*; D010748:Phosphopeptides / Q000032:analysis*; D011506:Proteins / Q000032:analysis*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
chemical_list: D002241:Carbohydrates; D005841:Gentisates; D010455:Peptides; D010748:Phosphopeptides; D011506:Proteins; C010925:2,5-dihydroxybenzoic acid