米托蒽醌与双链及三链核酸相互作用的电喷雾质谱研究

The interaction of mitoxantrone (MXT) with duplex and triplex DNA, contain repeating sequence CTCT, CCTT and CTT were studied by electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI-FTICR-MS). The 1:3 specific complexes of mitoxantrone and duplex DNA and 1:2 specific complexes of mitoxantrone and triplex DNA were observed. The results show that mitoxantrone has no remarkable sequence selectivity, however it has distinct structure selectivity, and destabilization the triplex.

Injection, Transport, Absorption and Phosphorescence Properties of a Series of Blue-Emitting Ir(III) Emitters in OLEDs: a DFT and Time-Dependent DFT Study

Quantum-chemistry methods were explored to investigate the electronic structures, injection and transport properties, absorption and phosphorescence mechanism of a series of blue-emitting Ir(III) complexes {[(F-2-ppy)(2)Ir(pta -X/pyN4)], where F-2-ppy = (2,4-difluoro)phenylpyridine; pta = pyridine-1,2,4-triazole; X = phenyl(1); p-tolyl (2); 2,6-difluororophenyl (3); -CF3 (4), and pyN4 = pyridine-1,2,4-tetrazolate (5)}, which are used as emitters in organic light-emitting diodes (OLEDs). The mobility of hole and electron were studied computationally based on the Marcus theory. Calculations of Ionization potentials (IPs) and electron affinities (EAs) were used to evaluate the injection abilities of holes and electrons into these complexes.

Theoretical studies on electronic structures, spectra and charge transporting properties of a series of Pt((CN)-N-Lambda)(2) complexes

We report a quantum-chemical study of electronic, optical and charge transporting properties of four platinum (II) complexes, pt((CN)-N-Lambda)(2) ((CN)-N-Lambda=phenylpyridine or thiophenepyridine). The lowest-lying absorptions at 442, 440, 447 and 429 nm are all attributed to the mixed transition characters of metal-to-ligand charge transfer (MLCT) and ligand-centered (LC) pi - pi(*) transition. While, unexpectedly, the lowest-lying phosphorescent emissions at 663, 660, 675 and 742 nm are mainly from metal-to-ligand charge transfer ((MLCT)-M-3) ligand-centered (LC) pi ->pi* transition. Ionization potential (IP), electron affinities (EA) and reorganization energy P (lambda(hole/electron)) were obtained to evaluate the charge transfer and balance properties between hole and electron.

Single-walled carbon nanohorn as new solid-phase extraction adsorbent for determination of 4-nitrophenol in water sample

Single-walled carbon nanohorn (SWCNH) was developed as new adsorbent for solid-phase extraction using 4-nitrophenol as representative. The unique exoteric structures and high surface area of SWCNH allow extracting a large amount of 4-nitrophenol over a short time. Highly sensitive determination of 4-nitrophenol was achieved by linear sweep voltammetry after only 120 s extraction. The calibration plot for 4-nitrophenol determination is linear in the range of 5.0 x 10(-8) M-1.0 x 10(-5) M under optimum conditions. The detection limit is 1.1 x 10(-8) M. The proposed method was successfully employed to determine 4-nitrophenol in lake water samples, and the recoveries of the spiked 4-nitrophenol were excellent (92-106%).

Screening and Structural Characterization of alpha-Glucosidase Inhibitors from Hawthorn Leaf Flavonoids Extract by Ultrafiltration LC-DAD-MSn and SORI-CID FTICR MS

In vitro a-glucosidase inhibition assays and ultrafiltration liquid chromatography with photodiode array detection coupled to electrospray ionization tandem mass spectrometry (ultrafiltration LC-DAD-ESI-MSn) were combined to screen a-glucosidase inhibitors from hawthorn leaf flavonoids extract (HLFE). As a result, four compounds were identified as alpha-glucosidase inhibitors in the HLFE, and their structures were confirmed to be quercetin-3-O-rha-(1-4)-glc-rha and C-glycosylflavones (vitexin-2 ''-O-glucoside, vitexin-2 ''-O-rhamnoside and vitexin) by high-resolution sustained off resonance irradiation collision-induced dissociation (SORI-CID) data obtained by Fourier transform ion cyclotron resonance mass spectrometry (FTICR MS).

Studies on Triterpenoids and Flavones in Glycyrrhiza uralensis Fisch by HPLC-ESI-MSn and FT-ICR-MSn

Seven compounds, four flavones and three triterpenoids from Glycyrrhiza uralensis Fisch. extract are identified by high performance liquid chromatography coupled with electrospray ionization multi-tandem mass spectrometry (HPLC-ESI-MSn). The fragmentation pathways of these compounds are investigated by ESI-MSn and Fourier transform ion cyclotron resonance multiple-stage tandem mass spectrometry (FT-ICR-MSn). Comparing the retention times (t(R)) and mass spectra with those of reference compounds, seven components are identified in Glycyrrhiza uralensis Fisch. and their MSn data proposed plausible schemes for their fragmentation. All the experimental results show that ESI-MSn and FT-ICR-MSn are powerful tools for the structural characterization of triterpenoids and flavones

Analysis of Saponins from Leaves of Aralia elata by Liquid Chromatography and Multi-stage Tandem Mass Spectrometry

Four saponins were isolated from the leaves of Aralia elata, and established using NMR and other spectroscopic methods, as well as data reported in the literature. Three Aralia saponins from the leaves of Aralia elata sharing the same structures as those isolated from the root bark suggested that the leaves would be a good substitute for the root bark of Aralia elata. These four Aralia saponins were then extensively investigated using complementarily positive and negative electrospray ionization multistage tandem mass spectrometry (ESI-MSn). Two isomers of saponins with different sugar linkages were then successfully differentiated by positive ESI-MSn and verified with different retention times and the collision-induced dissociation (CID) spectra by LC-MS. A simple and effective LC-MS method was thus developed for the rapid identification and screening of these saponins in plant extracts from leaves of Aralia elata.

Chemical Bonding and Electronic Structure of 4d-Metal Monosulfides

Bond distances, vibrational frequencies, dissociation energies, electron affinities, ionization potentials and dipole moments of the title molecules in neutral and charged ions were studied by use of density functional method. Ground states for each molecule were assigned. The calculated bond distance decreases with the increasing of atomic number of 4d metals, reaches minimum at RhS, then increases. For cationic molecules, the calculated bond distance decreases to the minimum at MoS+, then increases. The calculated vibrational frequency decreases from YS(YS+) to PdS(PdS+) for both neutral and cationic molecules. The bond ionic character decreases from YS(YS+) to PdS(PdS+) for neutral and cationic molecules. The bonding patterns are discussed and compared with the available studies.

Performance Enhancement of Polymer Light-Emitting Diodes by Using Ultrathin Fluorinated Polyimide Modifying the Surface of Poly(3,4-ethylene dioxythiophene):Poly(styrenesulfonate)

Herein, an insulating fluorinated polyimide (F-PI) is utilized as an ultrathin buffer layer of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) in polymer light-emitting diodes to enhance the device performance. The selective solubility of F-PI in common solvents avoids typical intermixing interfacial problems during the sequential multilayer spin-coating process. Compared to the control device, the F-PI modification causes the luminous and power efficiencies of the devices to be increased by a factor of 1.1 and 4.7, respectively, along with almost 3-fold device lifetime enhancement. Photovoltaic measurement, single-hole devices, and X-ray photoelectron spectroscopy, are utilized to investigate the underlying, mechanisms, and it is found that the hole injection barrier is lowered owing to the interactions between the PEDOT:PSS and F-PI. The F-PI modified PEDOT:PSS layer demonstrates step-up ionization potential profiles from the intrinsic bulk PEDOT:PSS side toward the F-PI-modified PEDOT:PSS surface, which facilitate the hole injection.

Evaluation of Effects of Bivalent Cations on the Formation of Purine-rich Triple-Helix DNA by ESI-FT-MS

The GGA triplet repeats are widely dispersed throughout eukaryotic genomes. (GGA)n or (GGT)n oligonucleotides can interact with double-stranded DNA containing (GGA:CCT)n to form triple-stranded DNA. The effects of 8 divalent metal ions (3 alkaline-earth metals and 5 transition metals) on formation of these purine-rich triple-helix DNA were investigated by electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI-FT-MS). In the absence of metal ions, no triplex but single-strand, duplex, and purine homodimer ions were observed in mass spectra. The triple-helix DNA complexes were observed only in the presence of certain divalent ions. The effects of different divalent cations on the formation of purine-rich triplexes were compared. Transition-metal ions, especially Co2+ and Ni2+, significantly boost the formation of triple-helix DNA, whereas alkaline-earth metal ions have no positive effects on triplex formation. In addition, Ba2+ is notably beneficial to the formation of homodimer instead of triplex.

大青叶正丁醇提取物化学成分的HPLC/ESI-MSn研究

High performance liquid chromatography-electrospray ionization mass spectrometry(HPLC/ESI-MSn) was applied to analyze the chemical constituents from n-BuOH extract of Folium Isatidis.The data of retention time,UV spectra,molar masses and structural information on the compounds were obtained.Seventeen compounds are found in extract from n-BuOH.There are four nucleosides,two purines and eleven flavones.

Lung alveolar proteomics of bronchoalveolar lavage from a pulmonary alveolar proteinosis patient using high-resolution FTICR mass spectrometry

High-resolution Fourier transform ion cyclotron resonance (FTICR) mass spectrometry was developed and applied to the proteome analysis of bronchoalveolar lavage fluid (BALF) from a patient with pulmonary alveolar proteinosis. With use of 1-D and 2-D gel electrophoresis, surfactant protein A (SP-A) and other surfactant-related lung alveolar proteins were efficiently separated and identified by matrix-assisted laser desorption/ionization FTICR mass spectrometry . Low molecular mass BALF proteins were separated using a gradient 2-D gel. An efficient extraction/precipitation system was developed and used for the enrichment of surfactant proteins. The result of the BALF proteome analysis show the presence of several isoforms of SP-A, in which an N-non-glycosylierte form and several proline hydroxylations were identified. Furthermore, a number of protein spots were found to contain a mixture of proteins unresolved by 2-D gel electrophoresis, illustrating the feasibility of high-resolution mass spectrometry to provide identifications of proteins that remain unseparated in 2-D gels even upon extended pH gradients.