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231.
Multifunctional ZrO2 nanoparticles (NPs) and ZrO2-SiO2 nanorods (NRs) have been successfully applied as the matrices for cyclodextrins and as affinity probes for enrichment of
peptides (leucine-enkephalin, methionine-enkephalin and thiopeptide), phosphopeptides (from tryptic digestion products of
β-casein) and phosphoproteins from complex samples (urine and milk) in atmospheric pressure matrix-assisted laser desorption/ionization
(MALDI) mass spectrometry (MS) and MALDI time-of-flight (TOF) MS. The results show that the ZrO2 NPs and ZrO2-SiO2 NRs can interact with target molecules (cyclodextrins, peptides, and proteins), and the signal intensities of the analytes
were significantly improved in MALDI-MS. The maximum signal intensities of the peptides were obtained at pH 4.5 using ZrO2 NPs and ZrO2-SiO2 NRs as affinity probes. The limits of detection of the peptides were found to be 75-105 fmol for atmospheric pressure MALDI-MS
and those of the cyclodextrins and β-casein were found to be 7.5-20 and 115-125 fmol, respectively, for MALDI-TOF-MS. In addition,
these nanomaterials can be applied as the matrices for the analysis of cyclodextrins in urine samples by MALDI-TOF-MS. ZrO2 NPs and ZrO2-SiO2 NRs efficiently served as electrostatic probes for peptide mixtures and milk proteins because 2–11 times signal enhancement
can be achieved compared with use of conventional organic matrices. Moreover, we have successfully demonstrated that the ZrO2 NPs can be effectively applied for enrichment of phosphopeptides from tryptic digestion of β-casein. Comparing ZrO2 NPs with ZrO2-SiO2 NRs, we found that ZrO2 NPs exhibited better affinity towards phosphopeptides than ZrO2-SiO2 NRs. Furthermore, the ZrO2 and ZrO2-SiO2 nanomaterials could be used to concentrate trace amounts of peptides/proteins from aqueous solutions without tedious washing
procedures. This approach is a simple, straightforward, separation-and washing-free approach for MALDI-MS analysis of cyclodextrins,
peptides, proteins, and tryptic digestion products of phosphoproteins.
相似文献
232.
Divya KP Sreejith S Suresh CH Ajayaghosh A 《Chemical communications (Cambridge, England)》2010,46(44):8392-8394
A chiral π-conjugated oligomer having alternate bipyridine and carbazole moieties connected through acetylinic bonds undergoes helical folding in chloroform-acetonitrile (40/60, v/v) as evident by fluorescence and circular dichroism changes. In the presence of transition metal cations such as Zn(2+) defolding of the helical conformation occurs. Upon decomplexation of the cation with EDTA, the helical conformation is regained. 相似文献
233.
Gabbutt CD Heron BM Kilner C Kolla SB 《Chemical communications (Cambridge, England)》2010,46(44):8481-8483
Novel, highly coloured benzopentalenonaphthalenones result from a cascade process initiated by the thermally-induced ring-opening of diarylmethanol substituted 2H-naphtho[1,2-b]pyrans in the presence of acid. 相似文献
234.
The cytotoxicity of 39 compounds, including eighteen flavonoids (flavanones, 1-10; flavones, 11-17; flavanol, 18), sixteen phenolic acid derivatives (aromatic acids, 19-24; aldehyde, 25; esters, 26-34) and five glycerides (35-39), isolated from Mexican propolis, were evaluated against a panel of six different cancer cell lines; murine colon 26-L5 carcinoma, murine B16-BL6 melanoma, murine Lewis lung carcinoma, human lung A549 adenocarcinoma, human cervix HeLa adenocarcinoma and human HT-1080 fibrosarcoma. A phenylpropanoid-substituted flavanol, (2R,3S)-8-[4-phenylprop-2-en-1-one]-4',7-dihydroxy-3',5-dimethoxyflavan-3-ol (18), showed the most potent cytotoxicity against A549 cells (IC50, 6.2 microM) and HT-1080 cells (IC50, 3.9 microM), stronger than those of the clinically used anticancer drug, 5-fluorouracil (IC50, 7.5 microM and 5.4 microM, respectively). Based on the observed results, the structure-activity relationships are discussed. 相似文献
235.
Diphenyl diamine-based phosphonyl imines attached by the N-isopropyl group in the auxiliary have been synthesized in good yields under convenient reaction conditions. These new chiral N-phosphonyl imines can react with glycine enolate smoothly to give chiral α-β diamino esters in good yields (72%–90%) and up to excellent diastereoselectivity (>99:1 dr). By treatment with HBr, the chiral auxiliary can be readily removed. The absolute structure has been unambiguously determined by converting a product to a known sample. 相似文献
236.
237.
Kulkarni NV Budagumpi S Kurdekar GS Revankar VK Didagi S 《Chemical & pharmaceutical bulletin》2010,58(12):1569-1575
A novel Cu(II) and Zn(II) complexes of triazolo-quinoline derivatives were synthesized by in situ method and were characterized by the spectro-analytical methods and their pharmacological properties were evaluated. The compound C3 has exhibited promising anticonvulsant activity towards the electroshock induced seizures in Wistar rats and possesses low toxicity, providing a high safety profile. 相似文献
238.
Template-free cross-linking of single-stranded DNA bearing octadiynyl side chains at the 7-position of 8-aza-7-deazapurine moieties with bisfunctional azides is reported employing a Cu(I)-catalyzed azide-alkyne "bis-click" reaction. Bis-adducts were formed when the bis-azide:oligonucleotide ratio was 1:1; monofunctionalization occurred when the ratio was 15:1. Four-stranded DNA consisting of two cross-linked duplexes was obtained after hydridization. Cross-linked duplexes are as stable as individual duplexes when ligation was introduced at terminal positions; ligation at a central position led to a slight duplex destabilization. 相似文献
239.
The gemini surfactant N-N′bis(dimethyldodecyl)-1,4-butanediammonium dibromide (12-4-12) was synthesized and its critical micelle concentrations (CMCs) and degree of counterion dissociation (α) in aqueous solutions in the presence of alkanols viz ethanol, isomeric butyl alcohols, 1-hexanol and alkanediols (ethanediol, 1,4-butanediol, 1,2-hexanediol, 2,5-hexanediol 1,6-hexanediol, and 1,8-octanediol) determined from electrical conductivity are reported. While ethanol, ethanediol, 1,4-butanediol showed an increase in CMC, a decrease was seen for isomeric butyl alcohols, 1-hexanol, isomeric hexanediols and 1,8-octanediol. For butyl alcohols the CMC decrease showed the trend 1° >2° > 3°; in C6 diols, 1,2-hexanediol exerted more decrease as compared to 2,5-hexanediol and 1,6-hexanediol.The results are explained on the basis of the structure and hydrophobicity of alcohols that determine their effect as cosolvent or cosurfactant (partitioning in micelles). Two-dimensional nuclear overhauser enhancement spectroscopy (2D-NOESY) was used to examine the location for 1-butanol and 1,4-butanediol in micellar systems as representative additives from alkanols and alkanediols showing CMC decreasing and increasing effect respectively. 相似文献
240.
D.M. Raj KumarM. Manivel Raja K. PrabaharV. Chandrasekaran Asok PoddarR. Ranganathan K.G. Suresh 《Journal of magnetism and magnetic materials》2011,323(13):1750-1754
The effect of Si/Ge ratio on resistivity and thermopower behavior has been investigated in the magnetocaloric ferromagnetic Gd5SixGe4−x compounds with x=1.7-2.3. Microstructural studies reveal the presence of Gd5(Si,Ge)4-matrix phase (5:4-type) along with traces of secondary phases (5:5 or 5:3-type). The x=1.7 and 2.0 samples display the presence of a first order structural transition from orthorhombic to monoclinic phase followed by a magnetic transition of the monoclinic phase. The alloys with x=2.2 and 2.3 display only magnetic transitions of the orthorhombic phase. A low temperature feature apparent in the AC susceptibility and resistivity data below 100 K reflects an antiferromagnetic transition of secondary phase(s) present in these compounds. The resistivity behavior study correlates with microstructural studies. A large change in thermopower of −8 μV/K was obtained at the magneto-structural transition for the x=2 compound. 相似文献