A Self-Assembled Matrix Monolayer for UV-MALDI Mass Spectrometry

Abstract

Matrix-assisted laser desorption/ionization (MALDI) mass spectrometry has in recent years significantly advanced the field of polymer analysis. However, the mechanisms of the desorption and ionization processes, and in particular the critical role played by the matrix, remain unclear. In the present work, the usual matrix is replaced with a self-assembled monolayer consisting of a UV absorbing matrix-like compound covalently linked to a gold surface. Analytes such as proteins or oligonucleotides are directly deposited on the covalently modified probe tips and mass analyzed by laser desorption time of flight (TOF) mass spectrometry. Several types of monolayers were investigated and tested for their ability to produce positive and negative analyte ions. Molecular ion signals were obtained for dT10 oligonucleotides and proteins as large as cytochrome C on monolayers of methyl N-(4-mercaptophenyl)carbamate (MMPC). The amenability of this model system to characterization with established physical and chemical methods should help investigate the processes involved in MALDI.

CHCA-modified Au nanoparticles for laser desorption ionization mass spectrometric analysis of peptides

“…Peaks at m/z 191 and 145 were detected on the surface of citrate-capped AuNPs, corresponding to dihydrogen citrate anion and anion of hydrogen citrate with loss of carboxyl, respectively. For cysteamine-capped AuNPs, an oxidized derivate of cysteamine at m/z 124 was detected, providing the evidence for capping of cysteamine on the surface of AuNPs [33]. Additionally, dihydrogen citrate anions were found on the surface of cysteaminecapped AuNPs.…”

“…UV-absorbing molecules, such as CHCA [29,30], 2,5-dihydroxybenzoic acid [31,32], and selfassembled monolayer reagents such as methyl N-(4-mercaptophenyl)carbamate [33], have been immobilized on the solid support surface to assist the desorption ionization of samples in SALDI-MS. Presence of a proton donor and high extinction coefficients at laser exciting wavelengths are crucial for MALDI [34] and SALDI-MS [22,35].…”

Specific Capture of Mammalian Cells by Cell Surface Receptor Binding to Ligand Immobilized on Gold Thin Films

“…Arrays prepared on gold thin films are compatible with many detection methods such as conventional phase contrast bright field microscopy, fluorescence microscopy, mass spectrometry (MALDI), and surface plasmon resonance (SPR) imaging, as well as electrochemical detection methods. (17)(18)(19) We also demonstrate the difference between cell binding and cell adhesion assays. (21,22) We tested the specificity of the receptor-ligand interaction in two ways.…”

Electroless plating of silver nanoparticles on porous silicon for laser desorption/ionization mass spectrometry

“…The SALDI technique utilizes substrates, which generally do not significantly desorb with analytes together, to bring analytes to be desorbed and ionized. Many effective SALDI-assisted materials have also been discovered , such as pencil lead [3], carbon nanotubes [4][5][6][7][8][9], porous silicon [10][11][12][13], metal and metal oxide powders [14][15][16][17][18][19][20][21][22][23][24][25][26][27][28]. One of the most widely used SALDI substrates is porous silicon.…”