Effect of surface capping of quantum dots (CdTe) on proteomics

RATIONALE: Investigation of nanoparticles for laser desorption/ionization mass spectrometry (LDI-MS) is routinely reported. However, the effect of surface capping of nanomaterials for LDI-MS is not well studied. METHODS: Different capping agents of quantum dots (CdTe) affect the spectra quality and sensitivity of protein analysis and protein digestion using trypsin enzyme assisted by microwave. Surface modification of CdTe quantum dots with different capping agents, namely 3-mercaptopropionic acid (3-MPA), 4-aminothiophenol (4-ATP), 4-mercaptobenzoic acid (4-MBA), 11-mercaptoundecanoic acid (11-MUA), cysteine (Cys) and thioglycolic acid (TG), were investigated for quantum dots (QDs)-assisted trypsin protease followed by analysis using mass spectrometry. RESULTS: CdTe QDs were used as a surface to assist trypsin protease and laser desorption/ionization mass spectrometry (surface-assisted laser desorption/ionization mass spectrometry, SALDI-MS). The MS profiles for the investigated analytes (bovine serum albumin (BSA), lysozyme, cytochrome c, alpha-casein, transferrin and myoglobin) revealed almost the absence of degradation that implies the softness of the present technique. QDs-assisted LDI-MS offered high sensitivity and high resolution. QDs showed significant enhancement of microwave-assisted trypsin digestion of the investigated proteins and these improvements boosted the identifications of fragments with a database. CONCLUSIONS: A capping agent of quantum dots affects the analysis of proteins and peptides using LDI-MS. CdTe QDs offer sensitive, high-resolution and simple analysis of proteins. QDs improved the protein digestion using the microwave-assisted trypsin digestion. Copyright (C) 2016 John Wiley & Sons, Ltd.