Zeper Abliz

Integrated ionization approach for RRLC-MS/MS-based metabonomics: finding potential biomarkers for lung cancer.

An integrated ionization approach of electrospray ionization (ESI), atmospheric pressure chemical ionization (APCI), and atmospheric pressure photoionization (APPI) combining with rapid resolution liquid chromatography mass spectrometry (RRLC-MS) has been developed for performing global metabonomic analysis on complex biological samples. This approach was designed to overcome the low ionization efficiencies of endogenous metabolites due to diverse physicochemical properties as well as ion suppression, and obtain comprehensive metabolite profiles in LC-MS analysis. Ionization capability and applicability were manifested by improved ionization efficiency and enlarged metabolite coverage in analysis on typical urinary metabolite standards and urine samples from healthy volunteers. The method was validated by the limit of detection and precision. When applied to the global metabonomic studies of lung cancer, more comprehensive biomarker candidates were obtained to reflect metabolic traits between healthy volunteers and lung cancer patients, including 74 potential biomarkers in positive ion mode and 59 in negative ion mode. Taking identical potential biomarkers of any two or three ionization methods into account, analysis using ESI-MS in positive (+) and negative (-) ion mode contributed to 70 and 64% of the total potential biomarkers, respectively. The biomarker discovery capability of (+/-) APCI-MS accounted for 45 and 42% of the overall; meanwhile (+/-) APPI-MS amounted for 39 and 54%. These results indicated that potential biomarkers with vital biological information could be missed if only a single ionization method was used. Furthermore, 11 potential biomarkers were identified including amino acids, nucleosides, and a metabolite of indole. They revealed elevated amino acid and nucleoside metabolism as well as protein degradation in lung cancer patients. This proposed approach provided a more comprehensive picture of the metabolic changes and further verified identical biomarkers that were obtained simultaneously using different ionization methods.

Global and Targeted Metabolomics of Esophageal Squamous Cell Carcinoma Discovers Potential Diagnostic and Therapeutic Biomarkers

Diagnostic and therapeutic biomarkers useful for esophageal squamous cell carcinoma (ESCC) have the ability to increase the long term survival of cancer patients. A metabolomics study, using plasma from four groups including ESCC patients before, during, and after chemoradiotherapy (CRT) and healthy controls, was originally carried out by LC-MS to determine global alterations in the metabolic profiles and find biomarkers potentially applicable to diagnosis and monitoring treatment effects. It is worth pointing out that a clear clustering and separation of metabolic data from the four groups was observed, which indicated that disease status and treatment intervention resulted in specific metabolic perturbations in the patients. A series of metabolites were found to be significantly altered in ESCC patients versus healthy controls and in pre- versus post-treatment patients based on multivariate statistical data analysis (MVDA). To further validate the reliability of these potential biomarkers, an independent validation was performed by using the selected reaction monitoring (SRM) based targeted approach. Finally, 18 most significantly altered plasma metabolites in ESCC patients, relative to healthy controls, were tentatively identified as lysophosphatidylcholines (lysoPCs), fatty acids, l-carnitine, acylcarnitines, organic acids, and a sterol metabolite. The classification performance of these metabolites were analyzed by receiver operating characteristic (ROC)1 analysis and a biomarker panel was generated. Together, biological significance of these metabolites was discussed. Comparison between pre- and post-treatment patients generated 11 metabolites as potential therapeutic biomarkers that were tentatively identified as amino acids, acylcarnitines, and lysoPCs. Levels of three of these (octanoylcarnitine, lysoPC(16:1), and decanoylcarnitine) were closely correlated with treatment effect. Moreover, variation of these three potential biomarkers was investigated over the treatment course. The results suggest that these biomarkers may be useful in diagnosis, as well as in monitoring therapeutic responses and predicting outcomes of the ESCC.

Palladium(II)-Directed Self-Assembly of Dynamic Donor−Acceptor [2]Catenanes

Highly efficient syntheses of donor-acceptor [2]catenanes were developed using a combination of templation and reversible metal-ligand coordination. The desired [2]catenanes were obtained within minutes through a five-component assembly, involving a donor-containing crown ether, an acceptor-containing ligand, two Pd(II) metal centers, and a dipyridyl ligand. The [2]catenane formation was characterized by 1H NMR and UV-vis spectroscopies and cold-spray ionization mass spectrometry. In particular, great translational selectivity was observed when a crown ether with two different donor units was employed.

RRLC-MS/MS-based metabonomics combined with in-depth analysis of metabolic correlation network: finding potential biomarkers for breast cancer

A metabonomics strategy based on rapid resolution liquid chromatography/tandem mass spectrometry (RRLC-MS/MS), multivariate statistics and metabolic correlation networks has been implemented to find biologically significant metabolite biomarkers in breast cancer. RRLC-MS/MS analysis by electrospray ionization (ESI) in both positive and negative ion modes was employed to investigate human urine samples. The resulting data matrices were analyzed using multivariate analysis. Application of orthogonal projections to latent structures discriminate analysis (OPLS-DA) allowed us to extract several discriminated metabolites reflecting metabolic characteristics between healthy volunteers and breast cancer patients. Correlation network analysis between these metabolites has been further applied to select more reliable biomarkers. Finally, high resolution MS and MS/MS analyses were performed for the identification of the metabolites of interest. We identified 12 metabolites as potential biomarkers including amino acids, organic acids, and nucleosides. They revealed elevated tryptophan and nucleoside metabolism as well as protein degradation in breast cancer patients. These studies demonstrate the advantages of integrating metabolic correlation networks with metabonomics for finding significant potential biomarkers: this strategy not only helps identify potential biomarkers, it also further confirms these biomarkers and can even provide biochemical insights into changes in breast cancer.

Design and Construction of Endo-Functionalized Multiferrocenyl Hexagons via Coordination-Driven Self-Assembly and Their Electrochemistry

The construction of a new family of endo-functionalized multiferrocenyl hexagons with various sizes via coordination-driven self-assembly is described. The structures of these novel metallacycles, containing several ferrocenyl moieties at their interior surface, are characterized by multinuclear NMR ((31)P and (1)H) spectroscopy, cold-spray ionization mass spectrometry (CSI-TOF-MS), elemental analysis, and molecular modeling. Insight into the structural and electrochemical properties of these endo-functionalized multiferrocenyl hexagons was obtained through cyclic voltammetry investigation.

Identification of new trace triterpenoid saponins from the roots of Panax notoginseng by high-performance liquid chromatography coupled with electrospray ionization tandem mass spectrometry

Triterpenoid saponins are the major bioactive constituents of Panax notoginseng. In the study reported here, the fragmentation behavior of triterpenoid saponins from P. notoginseng was investigated by electrospray ionization tandem mass spectrometry (ESI-MS(n))and high-performance liquid chromatography coupled with electrospray ionization tandem mass spectrometry (HPLC/ESI-MS(n)). Analyses revealed that product ions from glycosidic and cross-ring cleavages can give a wealth of structural information regarding the nature of the aglycone, sugar types, the sequence and linkage information of sugar units. It is noted that different glycosylation positions remarkably influenced the fragmentation behaviors, which could assist in the differentiation of saponin analogues. To rationalize this characteristic, the collision energy required for various glycosidic cleavages was investigated. According to the summarized fragmentation rules, identification of triterpenoid saponins from the roots of P. notoginseng could be fulfilled, even when reference standards were unavailable. Furthermore, minor and trace constituents were enriched and detected by eliminating the major constituents in one of the saponin fractions. As a result, a total of 151 saponins, including 56 new trace ones, were identified or tentatively characterized from saponin fractions based on their retention times, HPLC/HRMS, HPLC/ESI-MS(n) fragmentation behaviors and comparison with literature data.

Water-Soluble Pillar[7]arene: Synthesis, pH-Controlled Complexation with Paraquat, and Application in Constructing Supramolecular Vesicles

By the introduction of 14 anionic carboxylate groups at its two rims, a water-soluble pillar[7]arene (WP7) was synthesized. Its pH-controlled complexation with paraquat G1 in water was investigated. Host WP7 and guest G1 formed a 1:1 [2]pseudorotaxane with a high association constant of (2.96 ± 0.31) × 10(9) M(-1) in water. Furthermore, we took advantage of this novel molecular recognition motif to fabricate a supra-amphiphile based on WP7 and an amphiphilic paraquat derivative G2. The morphologies and sizes of self-assemblies of G2 and WP7⊃G2 were identified by transmission electron microscopy and dynamic light scattering.

Liquid chromatography-tandem mass spectrometry-based plasma metabonomics delineate the effect of metabolites' stability on reliability of potential biomarkers.

Metabonomics is an important platform for investigating the metabolites of integrated living systems and their dynamic responses to changes caused by both endogenous and exogenous factors. A metabonomics strategy based on liquid chromatography-mass spectrometry/mass spectrometry in both positive and negative ion modes was applied to investigate the short-term and long-term stability of metabolites in plasma. Principal components analysis and ten types of identified metabolites were used to summarize the time-dependent change rules in metabolites systematically at different temperatures. The long-term stability of metabolites in plasma specimens stored at -80 °C for five years was also studied. Analysis of these subjects identified 36 metabolites with statistically significant changes in expression (p < 0.05) and found a kind of metabolite with a hundred-fold change. The stability of metabolites in blood at 4 °C for 24 h was also investigated. These studies show that a thorough understanding of the effects of metabolite stability are necessary for improving the reliability of potential biomarkers.

π-Stacking Enhanced Dynamic and Redox-Switchable Self-Assembly of Donor–Acceptor Metallo-[2]Catenanes from Diimide Derivatives and Crown Ethers

Research interest in nanoscale molecular machines and devices has grown dramatically in the past a few decades. Interlocked molecules, for example, switchable catenanes and rotaxanes, have become the representative class of active components in molecular-based devices, such as molecular memories, nanovalves, and molecular muscles. Accompanying the quest for molecular machines with more sophisticated functions is the need for the convenient synthesis of such materials from readily available precursors. With the aid of preprogrammed interactions, such as hydrogen bonding, p stacking, anion templating, and metal– ligand coordination, many assembly strategies have been developed for the synthesis of functional interlocked molecules. In particular, donor–acceptor interactions have become a favorable driving force in the synthesis of electroand photoactive molecular machines because of the rich electrochemical and photophysical properties of p-electron donors and acceptors. Following the first template-directed synthesis of donor–acceptor [2]catenanes through a kinetic approach, thermodynamic approaches that use dynamic covalent chemistry, such as olefin metathesis, imine bond formation, and iodide-catalyzed N!C cleavage, have also been employed for the synthesis of such [2]catenanes. Recently, metal–ligand coordination has been utilized together with donor–acceptor interactions to give metallocatenanes. Scheme 1 illustrates an assembly strategy in which donor–acceptor [2]catenanes were obtained in high yields from an electron-rich crown ether (the donor), an electron-deficient ditopic ligand (the acceptor), two Pd centers (the connectors), and a linking ditopic ligand (the filler). Donor–acceptor interactions between a crown ether (4–6) and bipyridinium 1c (BPy) led to the formation of an inclusion complex, and the involvement of two [Pd(en)] (2 ; en=ethylenediamine) and one neutral bipyridine 3a closed the macrocycle to give a rectangular cavity that was optimal for alternative arrangements of the p systems. Although it was obvious that both donor–acceptor interactions and metal–ligand coordination were responsible for the high self-assembly efficiency, the way in which the two types of interaction balance with each other to ensure that efficiency still remains to be investigated. This issue was tested by comparing the self-assembly results while varying donor–acceptor pairs with different interaction strengths. Among the limited examples, BPy-based p acceptors have been the major electron-deficient unit used to template the formation of donor–acceptor [2]catenanes. Neutral naphthalene diimide (NDI) and Pyromellitic diimide (PmI) units, on the other hand, are readily available electron-deficient p acceptors that have been incorporated in a variety of supramolecular systems. Similarly to BPy derivatives, they were able to form inclusion complexes with p-electron-rich crown ethers. Their p-accepting ability, how[a] G. Koshkakaryan, Dr. Y. Liu The Molecular Foundry, Lawrence Berkeley National Laboratory One Cyclotron Road Berkeley, California, 94720 (USA) Fax: (+1)510-486-6287 E-mail : yliu@lbl.gov [b] G. Koshkakaryan University of California, Berkeley Berkeley, California, 94720 (USA) [c] K. Parimal, Prof. Dr. A. H. Flood Department of Chemistry Indiana University Bloomington, Indiana, 47405 (USA) [d] J. He, Prof. Dr. Z. Abliz Institute of Materia Medica Chinese Academy of Medical Sciences and Peking Union Medical College Beijing 100050 (P. R. China) [e] Dr. X. Zhang Codexis, Inc. 200 Penobscot Drive Redwood City, California, 94063 (USA) Supporting information for this article is available on the WWW under http://dx.doi.org/10.1002/chem.200801590.

Air flow assisted ionization for remote sampling of ambient mass spectrometry and its application.

Ambient ionization methods are an important research area in mass spectrometry (MS) analysis. Under ambient conditions, the gas flow and atmospheric pressure significantly affect the transfer and focusing of ions. The design and implementation of air flow assisted ionization (AFAI) as a novel and effective, remote sampling method for ambient mass spectrometry are described herein. AFAI benefits from a high extracting air flow rate. A systematic investigation of the extracting air flow in the AFAI system has been carried out, and it has been demonstrated not only that it plays a role in the effective capture and remote transport of charged droplets, but also that it promotes desolvation and ion formation, and even prevents ion fragmentation during the ionization process. Moreover, the sensitivity of remote sampling ambient MS analysis was improved significantly by the AFAI method. Highly polar and nonpolar molecules, including dyes, pharmaceutical samples, explosives, drugs of abuse, protein and volatile compounds, have been successfully analyzed using AFAI-MS. The successful application of the technique to residue detection on fingers, large object analysis and remote monitoring in real time indicates its potential for the analysis of a variety of samples, especially large objects. The ability to couple this technique with most commercially available MS instruments with an API interface further enhances its broad applicability.