Multi-commutation in flow analysis: recent developments and applications

The concept of multi-commutation in flow analysis is revisited, and emphasis is given to recent methodological and applicative achievements. Multi-commutation is compatible with different flow patterns (unsegmented, segmented, pulsed, tandem) and amenable to concentration-oriented feedback mechanisms. Its exploitation has led to significant attainments mainly in relation to versatility of the flow system. Characteristics and potentialities of the multi-commuted flow systems are discussed, and guidelines for assisting methodological implementation are given.The number of applications has experienced remarkable increase during last years; therefore, the applicative part of this review is focused on the recent noteworthy applications, mainly in relation to environmental, agronomical, pharmaceutical, biological, food and industrial samples.     

Top-down mass spectrometry: recent developments, applications and perspectives

Top-down mass spectrometry is an emerging approach for the analysis of intact proteins. The term was coined as a contrast with the better-established, bottom-up strategy for analysis of peptide fragments derived from digestion, either enzymatically or chemically, of intact proteins. Although the term top-down originates from proteomics, it can also be applied to mass spectrometric analysis of intact large biomolecules that are constituents of protein assemblies or complexes. Traditionally, mass spectrometry has usually started with intact molecules, and in this regard, top-down approaches reflect the spirit of mass spectrometry. This article provides an overview of the methodologies in top-down mass spectrometry and then reviews applications covering protein posttranslational modifications, protein biophysics, DNAs/RNAs, and protein assemblies. Finally, challenges and future directions are discussed.     

Monolith-based immobilized enzyme reactors: recent developments and applications for proteome analysis

In the current proteome study, protein digestion is indispensable before proteins could be identified by MS/MS, no matter based on top-down or bottom-up strategies. Compared to the traditional digestion performed in free solution, immobilized enzyme shows great advantages in digestion speed, stability, and longevity, especially with monolithic materials as the supports. Besides the improved digestion capacity, the immobilized enzyme reactors (IMERs) could be further coupled with the separation and detection systems, enabling high-throughput protein identification. In this paper, the latest advances in the monolith-based IMERs and their applications in proteomic study are briefly summarized. By reviewing these achievements, it could be seen that monilith-based IMERs have very bright future in proteome analysis.     

Droplet microfluidics: recent developments and future applications

We report recent advances in the field of droplet-based microfluidics. Specifically, we highlight the unique features of such platforms for high-throughput experimentation; describe functional components that afford complex analytical processing and report on applications in synthesis, high-throughput screening, cell biology and synthetic and systems biology. Issues including the integration of high-information content detection methods, long term droplet stability and opportunities for large scale and intelligent biological experimentation are also discussed.     

Split-luciferase complementary assay: applications,recent developments,and future perspectives

Bioluminescent systems are considered as potent reporter systems for bioanalysis since they have specific characteristics, such as relatively high quantum yields and photon emission over a wide range of colors from green to red. Biochemical events are mostly accomplished through large protein machines. These molecular complexes are built from a few to many proteins organized through their interactions. These protein–protein interactions are vital to facilitate the biological activity of cells. The split-luciferase complementation assay makes the study of two or more interacting proteins possible. In this technique, each of the two domains of luciferase is attached to each partner of two interacting proteins. On interaction of those proteins, luciferase fragments are placed close to each other and form a complemented luciferase, which produces a luminescent signal. Split luciferase is an effective tool for assaying biochemical metabolites, where a domain or an intact protein is inserted into an internally fragmented luciferase, resulting in ligand binding, which causes a change in the emitted signals. We review the various applications of this novel luminescent biosensor in studying protein–protein interactions and assaying metabolites involved in analytical biochemistry, cell communication and cell signaling, molecular biology, and the fate of the whole cell, and show that luciferase-based biosensors are powerful tools that can be applied for diagnostic and therapeutic purposes.     

Biomimetic and bioinspired silica: recent developments and applications

In a previous review of biological and bioinspired silica formation (S. V. Patwardhan et al., Chem. Commun., 2005, 1113 [ref. 1]), we have identified and discussed the roles that organic molecules (additives) play in silica formation in vitro. Tremendous progress has been made in this field since and this review attempts to capture, with selected examples from the literature, the key advances in synthesising and controlling properties of silica-based materials using bioinspired approaches, i.e. conditions of near-neutral pH, all aqueous environments and room temperature. One important reason to investigate biosilicifying systems is to be able to develop novel materials and/or technologies suitable for a wide range of applications. Therefore, this review will also focus on applications arising from research on biological and bioinspired silica. A range of applications such as in the areas of sensors, coatings, hybrid materials, catalysis and biocatalysis and drug delivery have started appearing. Furthermore, scale-up of this technology suitable for large-scale manufacturing has proven the potential of biologically inspired synthesis.     

Prompt gamma neutron activation analysis (PGAA): recent developments and applications

Journal of Radioanalytical and Nuclear Chemistry - Prompt gamma neutron activation analysis has become an important part of the analytical toolkit, practiced at several research reactors worldwide....     

Broadband 1H homodecoupled NMR experiments: recent developments,methods and applications

In recent years, a great interest in the development of new broadband ¹H homonuclear decoupled techniques providing simplified J_HH multiplet patterns has emerged again in the field of small molecule NMR. The resulting highly resolved ¹H NMR spectra display resonances as collapsed singlets, therefore minimizing signal overlap and expediting spectral analysis. This review aims at presenting the most recent advances in pure shift NMR spectroscopy, with a particular emphasis to the Zangger–Sterk experiment. A detailed discussion about the most relevant practical aspects in terms of pulse sequence design, selectivity, sensitivity, spectral resolution and performance is provided. Finally, the implementation of the different reported strategies into traditional 1D and 2D NMR experiments is described while several practical applications are also reviewed. Copyright © 2015 John Wiley & Sons, Ltd.     

Exploring recent developments on 1,2,4-triazole: Synthesis and biological applications

Triazoles are nitrogen-bearing heterocycles. In the last few decades, researchers have focused on fused heterocycles, as they have better pharmacological effect compared to triazoles alone. Among the two isomers of triazole, this article aims to explore the work carried out on 1,2,4-triazole and N-bridged heterocycles derived from 1,2,4-triazole in last 18 years, highlight different synthetic pathways, and present a brief summary of the different biological activities possessed by 1,2,4-triazole derivatives. The information collected in this article is expected to help researchers to discover novel therapeutic agents for better applications in the field of pharmaceutical science.     

Iodine electrophiles in stereoselective reactions: recent developments and synthetic applications

The regio- and stereocontrolled functionalisation of carbon-carbon double bonds bears enormous potential in organic synthesis. This area has been extensively studied and reviewed as alkenes are amongst the most important starting materials for synthetic chemists, accessible in many varieties and in large quantities. We focus in this tutorial review only on recent developments using iodine electrophiles for the functionalisation of alkenes although transition-mediated reactions and functionalisations with chalcogen electrophiles also play an important role. New synthetic applications using this methodology showing scope and limitations of iodine-mediated processes also within the context of other electrophilic reactions are highlighted.     

Electron ionization in LC-MS: recent developments and applications of the direct-EI LC-MS interface

The purpose of this article is to underline the possibility of efficiently using electron ionization (EI) in liquid chromatography (LC) and mass spectrometry (MS). From a historical perspective, EI accompanied the first attempts in LC-MS but, owing to several technical shortcomings, it was soon outshined by soft, atmospheric pressure ionization (API) techniques. Nowadays, two modern approaches, supersonic molecular beam LC-MS and direct-EI LC-MS, offer a valid alterative to API, and preserve the advantages of EI also in LC-MS applications. These advantages can be summarized in three crucial aspects: automated library identification; identification of unknown compounds, owing to EI extensive fragment information; inertness to coeluted matrix interferences owing to very unlikely ion–ion and ion–molecule interactions in the EI gas-phase environment. The direct-EI LC-MS interface is a simple and efficient solution able to produce high-quality, interpretable EI spectra from a wide range of low molecular weight molecules of different polarity. Because of the low operative flow rates, this interface relies on a nano-LC technology that helps in reducing the impact of the mobile phase on the gas-phase environment of EI. This review provides an extensive discussion on the role of EI in LC-MS interfacing, and presents in detail several performance aspects of the direct-EI LC-MS interface, especially in terms of response, mass-spectral quality, and matrix effects. In addition, several key applications are also reported.     

Immobilized trypsin systems coupled on-line to separation methods: recent developments and analytical applications

The ability to rapidly and efficiently digest and identify an unknown protein is of great utility for proteome studies. Identification of proteins via peptide mapping is generally accomplished through proteolytic digestion with enzymes such as trypsin. Limitations of this approach consist in manual sample manipulation steps and extended reaction times for proteolytic digestion. The use of immobilized trypsin for cleavage of proteins is advantageous in comparison with application of its soluble form. Enzymes can be immobilized on different supports and used in flow systems such as immobilized enzyme reactors (IMERs). This review reports applications of immobilized trypsin reactors in which the IMER has been integrated into separation systems such as reversed-phase liquid chromatography or capillary electrophoresis, prior to MS analysis. Immobilization procedures including supports, mode of integration into separation systems, and methods are described.     

手性氨基醇在不对称催化中的应用及新进展

综述了手性氨基醇作为配体或催化剂在不对称合成中的应用及最新进展。     

Some recent developments on cost-effective flow-based analysis

This paper reviews some recent developments on cost-effective flow-based analysis. They include the newly developed Lab-at-Valve (LAV), concepts in using the stopped-flow injection approach, on-line sample pretreatment systems, including bead injection–flow injection and flow injection–ion-chromatography, systems for size-based speciation, and cost-effective reagents. Applications and advantages of such techniques are discussed.     

The oxa-Michael reaction: from recent developments to applications in natural product synthesis

In marked contrast to Michael reactions, oxa-Michael reactions have not been used as standard transformations in organic synthesis until quite recently. This was mainly due to a lack of reactivity and selectivity, although the potential products of such reactions are valuable intermediates. This tutorial review presents recent major advances in the field of oxa-Michael (sometimes called oxo-Michael or oxy-Michael) reactions and applications in the total synthesis of complex natural products.     

From fundamentals to applications: recent developments in atmospheric pressure photoionization mass spectrometry

Only five years after the first publication on atmospheric pressure photoionization (APPI), this technique has evolved rapidly as a very useful complement to established ionization techniques for liquid chromatography/mass spectrometry (LC/MS). This is reflected in a rapidly increasing number of publications in this field. On the one hand, thorough studies into the photoionization mechanism have provided deep insights into the roles and influences of the solvent, the dopant and other additives. On the other hand, a large number of new and attractive applications have recently been introduced. New instrumental developments have resulted in combined APPI/ESI (PAESI) and APPI/APCI sources and a microfabricated APPI source. In this review, the most important developments within the field are summarized, focusing in particular on the applications of the technique.     

Vacuum ultraviolet photoionization and photoelectron studies in the new millennium: recent developments and applications

Vacuum ultraviolet (VUV) photoionization mass spectrometry and photoelectron spectroscopy have played a central role in providing energetic and spectroscopic information for neutrals and cations. The most important data obtainable in a VUV photoionization and photoelectron experiment are ionization energies and 0 K ion dissociation thresholds or appearance energy (AE), from which 0 K bond dissociation energies for neutrals and cations can be deduced. The recent developments in VUV lasers and third-generation synchrotron sources, together with the introduction of the pulsed-field ionization (PFI), photoelectron (PFI-PE), and PFI-photoion (PFI-PI) methods, have revolutionized the field of photoelectron and ion spectroscopy by significantly improving the energy resolution to the range of 0.025–1.0 meV (full width at half maximum, FWHM). These resolutions, which make possible the measurement of photoelectron spectra for many simple molecules at the rotational-resolved level, are ≈100-fold better than those observed in traditional photoelectron studies, making the PFI-PE technique a true spectroscopic method. The recent introduction of the synchrotron-based PFI-PEPICO scheme has shown that AE values for a range of molecules can be determined with an unprecedented precision limited only by the PFI-PE measurement. The synchrotron-based PFI-PEPICO and PFI-PI schemes show great promises for future studies of state- or energy-selected ion-dissociation dynamics and energy-selected ion-molecule reaction dynamics. Further improvement in energy resolution for PFI-PE and PFI-PI measurements has been demonstrated using the two-color photo-induced Rydberg ionization (PIRI) spectroscopic scheme, which involves the photo-induced ionization of intermediate long-lived high-n ( n≥100) Rydberg states. The incorporation of this method by VUV photoexcitation to prepare intermediate high-n ( n≥100) Rydberg states is also expected to greatly increase the energy range of PFI studies. The availability of this array of laser- and synchrotron-based PFI methods, including PFI-PE, PFI-PEPICO, PFI-PI, PFI-ion-pair, and PIRI schemes, ensures an exciting and bright future for VUV photoionization and photoelectron studies in the new millennium.