On-plate desalting and SALDI-MS analysis of peptides with hydrophobic silicate nanofilms on a gold substrate.
We report the use of silicate nanofilms for on-plate desalting and subsequently direct laser desorption/ionization-mass spectrometric (LDI-MS) analysis of peptides. A hydrophobic octadecyltrichlorosilane (OTS) monolayer is formed on a calcinated nanofilm on a gold substrate to facilitate sample deposition and interaction with the surface that allows effective removal of MS-incompatible contaminants such as salts and surfactants by simple on-plate washing while the peptides are retained on the spot. By elimination of interferences from matrix-related ions and contaminants, sensitivity of MS analysis has been enhanced over ca. 20 times, leading to improved detection of peptides at the low-femtomolar level. A high recovery rate of the peptides is obtained by using relatively rough nanofilms, which are prepared through a modified layer-by-layer deposition/calcination process. The performance of the films has been investigated with peptide samples in the presence of high salts (NaCl and sodium acetate) and urea. Compared to matrix-assisted laser desorption/ionization analysis with CHCA matrix, LDI with on-plate desalting offers marked improvement for analysis of peptides due to low background ions and reduction of sample complexity. Additionally, selective capture of the hydrophobic components of a protein can be achieved, providing a highly useful strategy for specific peptide enrichment. LDI with on-plate desalting approach has also been successfully applied to peptide analysis from protein digests.
Department of Chemistry, University of California, Riverside, California 92521, United States.
Jicheng
J
Duan
Hui
H
Wang
Quan
Q
Cheng
D053000:Analytic Sample Preparation Methods / Q000379:methods*; D000818:Animals; D002417:Cattle; D006046:Gold / Q000737:chemistry*; D057927:Hydrophobic and Hydrophilic Interactions; D049329:Nanostructures / Q000737:chemistry*; D010446:Peptide Fragments / Q000737:chemistry; D010455:Peptides / Q000737:chemistry*; D012492:Salts / Q000737:chemistry; D012821:Silanes / Q000737:chemistry; D017640:Silicates / Q000737:chemistry*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods*
D010446:Peptide Fragments; D010455:Peptides; D012492:Salts; D012821:Silanes; D017640:Silicates; C061189:octadecyltrichlorosilane; D006046:Gold