Design Of Compatible Matrix For Analysis Of Biomolecules With MALDI-TOF-MS

Matrix-assisted laser desorption/ionization mass spectrometry(MALDI-MS)uses selected matrices,such as 2,5-Dihydroxybenzoic acid(DHB),a-cyano-4-hydroxycinnamic acid(HCCA),Sinapinic acid(SA)for the analysis of compounds i.e.protein,and peptide etc.The existing matrix produced fragmentation in the low mass region,therefore can't be used for the analysis of low molecular weight(LMW)analyte.Surface-assisted laser desorption ionization mass spectrometry(SALDI MS)has been developed to overcome poor reproducibility and high background in the low mass region,which commonly occurs in matrix-assisted laser desorption/ionization mass spectrometry(MALDI-MS).The endeavor of these works is to explore more thoroughly the behaviors of modified surface of different QDs to serve as the matrices for the analysis of carbohydrates and also utilize the sulfonic acid-functionalized mesoporous silica leading to the improvement of detection of glycoprotein/glycopeptides via high throughput technique i.e.MALDI-MS.1.Quantum dots assisted laser desorption/ionization mass spectrometric detection of carbohydrates:qualitative and quantitative analysisQuantum dots(QDs)assisted laser desorption/ionization mass spectrometric(QDA-LDI-MS)strategy was proposed for qualitative and quantitative analysis of a series of carbohydrates.The adsorption of carbohydrates on the modified surface of different QDs as the matrices depended mainly on the formation of hydrogen bonding,which led to higher MS intensity than those with conventional organic matrix.The effects of QDs concentration and sample preparation method were explored for improving the selective ionization process and the detection sensitivity.The proposed approach offered a new dimension to the application of QDs as matrices for MALDI-MS research of carbohydrates.It could be used for quantitative measurement of glucose concentration in human serum with good performance.The QDs served as a matrix showed the advantages of low background,higher sensitivity,convenient sample preparation and excellent stability under vacuum.The QDs assisted LDI-MS approach has promising application to the analysis of carbohydrates in complex biological samples.2.Efficient enrichment of glycopeptides with sulfonic acid-functionalized mesoporous silicaThis work presents an efficient and selective enrichment method for glycoprotein/glycopeptides with sulfonic acid-functionalized mesoporous silica(SBA-15-SO3H),which is synthesized via simple oxidation of-SH groups with H2O2.The functionalized SBA-15 shows large surface area and accessible pores,and can selectively adsorb glycopeptides via hydrogen bond and hydrophilic interaction.Upon the selective enrichment prior to the mass spectrometric(MS)analysis,the signals of glycopeptides are significantly enhanced,which leads to the identifiable signals of 21 glycopeptides from the digest of HRP,16 glycopeptides from the digest of human IgG,and 16 glycopeptides from the digest of chicken avidin.The SBA-15-SO3H gives significant selectivity for glycopeptides even at a low molar ratio of glycopeptides to nonglycopeptides with an enrichment time of 15 min.Therefore,this work provides a powerful material for selective enrichment and identification of low abundant glycopeptides in glycoproteomic analysis.