Facile synthesis of magnetic homochiral metal-organic frameworks for "enantioselective fishing".

Magnetic functionalized homochiral metal-organic frameworks (MOFs) were prepared and applied to efficient enantioselective fishing of chiral drug intermediates. Under optimized conditions, the enantiomeric excess (ee) value as high as 85.2% was achieved for methyl phenyl sulfoxide (MPS) within 3 min.

A lithium-rich composite metal oxide used as a SALDI-MS matrix for the determination of small biomolecules.

A lithium-rich composite metal oxide was evaluated as a novel matrix for matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-MS). The low background interference and lithium-rich feature made it a highly efficient matrix for the analysis of small molecules with high reproducibility, sensitivity and strong salt tolerance.

Phospholipids profiling and outcome of peritoneal dialysis patients.

OBJECTIVES: To investigate phospholipids (PLs) biomarkers in predicting outcome of patients undergoing peritoneal dialysis (PD). MATERIALS AND METHODS: Twenty PD patients were followed using baseline plasma PLs with an improved online two-dimensional liquid chromatography-quadrupole time-of-flight mass spectrometry system. RESULTS: Significant differences were observed in eight PL species with sphingomyelin (SM) and glycerophosphocholine between technical survival (n=15) and failure patients (n = 5). Cox regression showed SM 21:0 (adjusted HR 13.7, 95% CI 2.42-77.88, p = 0.003) was independently associated with patients technical failure. CONCLUSIONS: PD failure patients had different plasma PLs profiling as compared with survival patients. Elevated plasma SM 21:0 level may potentially serve as a biomarker of PD patients at risk for adverse outcomes.

GdF3 as a promising phosphopeptide affinity probe and dephospho-labelling medium: experiments and theoretical explanation.

Bone-like GdF3 was synthesized and applied for phosphopeptide enrichment for the first time. As a new kind of efficient phosphopeptide affinity probe, GdF3 exhibits high efficiency in the mediation of the dephosphorylation reaction. In addition, DFT calculations were introduced to theoretically explain the unique property of GdF3 compared to GdPO4, which is promising and can be potentially significant in protein phosphorylation research.

A facilely synthesized amino-functionalized metal-organic framework for highly specific and efficient enrichment of glycopeptides.

A facilely synthesized amino-functionalized metal-organic framework (MOF) MIL-101(Cr)-NH2 was first applied for highly specific glycopeptide enrichment based on the hydrophilic interactions. With the special characteristics of the MOF, the material performed well in selectivity and sensitivity for both standard glycoprotein samples and complex biological samples.

Guanidyl-functionalized graphene as a bifunctional adsorbent for selective enrichment of phosphopeptides.

Guanidyl-functionalized graphene (GFG) was designed and synthesized. By simple modulation of the loading buffer this novel bifunctional adsorbent provides two enriching functions, one for global phosphopeptides, and the other for multiphosphopeptides with consecutive phosphorylated residues. GFG provides a promising perspective for consecutive phosphorylated peptide enrichment in phosphor-proteomic research and related biological process studies.

Applications of ambient mass spectrometry in high-throughput screening.

The development of rapid screening and identification techniques is of great importance for drug discovery, doping control, forensic identification, food safety and quality control. Ambient mass spectrometry (AMS) allows rapid and direct analysis of various samples in open air with little sample preparation. Recently, its applications in high-throughput screening have been in rapid progress. During the past decade, various ambient ionization techniques have been developed and applied in high-throughput screening. This review discusses typical applications of AMS, including DESI (desorption electrospray ionization), DART (direct analysis in real time), EESI (extractive electrospray ionization), etc., in high-throughput screening (HTS).

SnO(2)-ZnSn(OH)(6): a novel binary affinity probe for global phosphopeptide detection.

ZnSn(OH)(6) and binary-component SnO(2)-ZnSn(OH)(6) were introduced as affinity probes for phosphopeptide enrichment for the first time. Two strategies, either ZnSn(OH)(6) and SnO(2) serial enrichment or binary-component SnO(2)-ZnSn(OH)(6) enrichment in a single run, were proposed to enhance multi-phosphopeptide enrichment and to significantly improve global phosphopeptide detection.

Increased dialysate levels of phospholipids containing unsaturated fatty acid are associated with increased peritoneal transport rate.

BACKGROUND: High peritoneal transport status in end-stage renal disease patients receiving peritoneal dialysis was shown to be associated with increased morbidity and mortality. Although the pathogenesis of increased peritoneal transport is still not clear, previous studies have demonstrated that phospholipids (PLs) are present on the peritoneal mesothelium and when added to dialysate can decrease the peritoneal fluid absorption rate and increase peritoneal fluid removal. In the present report, we explored the relationship between peritoneal transport and dialysate loss of endogenous PLs. METHODS: We evaluated 48 prevalent continuous ambulatory peritoneal dialysis patients with high or low peritoneal transport in a cross-sectional study. The 4-hour dwell dialysate PL profile was analyzed by high-performance liquid chromatography coupled with electrospray ionization ion trap mass spectrometry. The patients' peritoneal small solute transport rate was assessed by D/P(Cr) at 4 h and their fluid transport by kinetic modeling. RESULTS: While there were no significant differences between the 2 groups in age, sex, diabetic status and time on dialysis, high transporters had a significantly higher D/P(Cr) and peritoneal fluid absorption rate (K(e)) than low transporters. The PLs in dialysate effluents mainly consisted of PLs containing unsaturated fatty acid, and the concentrations, as well as the amount, of PLs were significantly elevated in the dialysate of high transporters as compared to low transporters. CONCLUSION: Our results showed that dialysate from high transporters exhibited elevated levels of PLs, especially PLs containing unsaturated fatty acid, suggesting a possible loss of peritoneal surface-active PLs in peritoneal dialysis, and this loss may contribute to the alteration in peritoneal transport.

A method to determine quercetin by enhanced luminol electrogenerated chemiluminescence (ECL) and quercetin autoxidation.

Quercetin greatly enhanced luminol electrochemiluminescence of quercetin in alkaline solution. When the concentration of luminol was 0.1 mol L(-1), the detection limit for quercetin was 2.0x10(-8) mol L(-1) with a linear range from 1.0x10(-7) to 2x10(-5) mol L(-1). The pH and buffer substantially affected ECL intensity. Quercetin was autoxidized in alkaline aqueous solution. The rate of autoxidation of quercetin in various pH buffers and borate concentrations were measured. Borate was found to inhibit quercetin autoxidation and compromise quercetin enhancement effect on luminol ECL to some extent. Two final autoxidation products were identified with LC-MS methods. Autoxidation process was associated with enhancement of ECL intensity. The ROS generated during quercetin autoxidation enhanced the ECL intensity.

[Identification of a naturally presented MAGE-A3 epitope on the surface of HLE cell line by mass spectrometry].

OBJECTIVE: To identify a naturally presented HLA-A2-restricted epitope of MAGE-A3 antigen, FLWGPRALV (MAGE-A3(271 - 279)), on the surface of a human hepatocellular carcinoma (HCC) cell line HLE. METHODS: Synthetic peptide FLWGPRALV, served as positive control target, was analyzed by HPLC and HPLC-ESI-TOF-MSMS, in order to determine its HPLC elution time, mass-spectrometric characteristics and the lowest detection limitation by the two approaches. 3 x 10(9) HLE cells were collected, peptides naturally presented by major histocompatibility complex (MHC) molecules on the cell surface were isolated by mild acid elution, and concentrated by lyophilization, then the mixtures of peptides were fractioned by HPLC. The ingredient ranged from 2 min before the elution time determined by the synthetic peptide to 2 min after that was collected, concentrated by lyophilization, and analyzed by HPLC-ESI-TOF-MSMS, to identify the existence of the MAGE-A3(271 - 279) peptide. RESULTS: The HPLC-ESI-TOF-MSMS detection provided an evidence for the existence of a doubly charged ion of (m/z)(2) 529.9, which was further analyzed by collision induced dissociation. The doubly charged ion was ultimately identified as the MAGE-A3(271 - 279) peptide, its amino sequence was FLWGPRALV and its molecular weight was 1058.4 Da. CONCLUSIONS: MAGE-A3(271 - 279) epitope could be naturally presented by HLA-A2 molecules to the surface of HCC cell line and MAGE-A3(271 - 279) peptide may have potential immunotherapeutic value in HCC patients.

Fabrication and characterization of stable ultrathin film micropatterns containing DNA and photosensitive polymer diazoresin.

Stable, ultrathin DNA micropatterns were fabricated from photosensitive polymer diazoresin (DR) through a self-assembly technique. The micropatterns were achieved on LBL ultrathin film after UV exposure through a photomask. The patterns were characterized systematically with scanning electron microscopy, atomic force microscopy, X-ray photoelectron spectroscopy and fluorescence microscopy. All of the results indicate that the combined LBL self-assembly and photolithography technique is a promising method for constructing stable, well-defined micropatterns with a nanoscale thickness.

[Determination of sildenafil in medicines for erectile dysfunction by capillary electrophoresis].

A method has been developed for the determination of sildenafil in the medicines for erectile dysfunction by capillary electrophoresis. The samples were analyzed with 60 mmol/L NaH2PO4(pH 5.0) running buffer at 35 degrees C capillary temperature and 30 kV voltage. A linear calibration was obtained from 0.07 g/L to 1.05 g/L of sildenafil (r = 0.9985) with the RSD of 4.7% for peak area, and the average recovery was 97.4%. The results were compared with those of HPLC, showing that the method is precise, simple and cost-effective, and can be used as a complementary method to HPLC.