Target-responsive Host-Guest binding-driven dual sensing readout for enhanced electrochemical chiral analysis

The Analyst ◽

10.1039/d1an00795e ◽

2021 ◽

Author(s):

Somaye Ebrahimi ◽

Abbas Afkhami ◽

Tayyebeh Madrakian

Keyword(s):

Convenient Method ◽

Chiral Discrimination ◽

Chiral Analysis ◽

Guest Binding ◽

Dual Sensing ◽

Enantioselective Sensing

Efﬁcient chiral discrimination with a convenient method remains a challenge in pharmaceutical and biotechnology. Our aim with this paper was to develop a dual-signaling enantioselective sensing strategy based on the...

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Application of Infrared Multiple Photon Dissociation (IRMPD) Spectroscopy in Chiral Analysis

Molecules ◽

10.3390/molecules25215152 ◽

2020 ◽

Vol 25 (21) ◽

pp. 5152

Author(s):

Yingying Shi ◽

Mengying Du ◽

Juan Ren ◽

Kailing Zhang ◽

Yicheng Xu ◽

...

Keyword(s):

Ion Trap ◽

Structural Information ◽

Theoretical Calculations ◽

Chiral Discrimination ◽

Chiral Analysis ◽

Chiral Molecules ◽

Chiral Complexes ◽

Irmpd Spectroscopy ◽

Infrared Multiple Photon Dissociation ◽

The Difference

In recent years, methods based on photodissociation in the gas phase have become powerful means in the field of chiral analysis. Among them, infrared multiple photon dissociation (IRMPD) spectroscopy is a very attractive one, since it can provide valuable spectral and structural information of chiral complexes in addition to chiral discrimination. Experimentally, the method can be fulfilled by the isolation of target diastereomeric ions in an ion trap followed by the irradiation of a tunable IR laser. Chiral analysis is performed by comparing the difference existing in the spectra of enantiomers. Combined with theoretical calculations, their structures can be further understood on the molecular scale. By now, lots of chiral molecules, including amino acids and peptides, have been studied with the method combined with theoretical calculations. This review summarizes the relative experimental results obtained, and discusses the limitation and prospects of the method.

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The Use of Dual Cyclodextrin Chiral Selector Systems in the Enantioseparation of Pharmaceuticals by Capillary Electrophoresis: An Overview

Molecules ◽

10.3390/molecules26082261 ◽

2021 ◽

Vol 26 (8) ◽

pp. 2261

Author(s):

Gabriel Hancu ◽

Lajos Attila Papp ◽

Gergő Tóth ◽

Hajnal Kelemen

Keyword(s):

Capillary Electrophoresis ◽

Efficient Solution ◽

Chiral Selector ◽

Chiral Discrimination ◽

Chiral Analysis ◽

Chiral Selectors ◽

Separation Of Enantiomers ◽

Pharmaceutical Substances ◽

Current Review ◽

General Aspects

Cyclodextrin (CD) derivatives are the most efficient and frequently used chiral selectors (CSs) in capillary electrophoresis (CE). There are situations when the use of a single CD as CS is not enough to obtain efficient chiral discrimination of the enantiomers; in these cases, sometimes this problem can be resolved using a dual CD system. The use of dual CD systems can often dramatically enhance enantioseparation selectivity and can be applied for the separation of many analytes of pharmaceutical interest for which enantioseparation by CE with another CS systems can be problematic. Usually in a dual CD system an anionic CD is used together with a neutral one, but there are situations when the use of a cationic CD with a neutral one or the use of two neutral CDs or even two ionized CDs can be an efficient solution. In the current review we present general aspects of the use of dual CD systems in the analysis of pharmaceutical substances. Several examples of applications of the use of dual CD systems in the analysis of pharmaceuticals are selected and discussed. Theoretical aspects regarding the separation of enantiomers through simultaneous interaction with the two CSs are also explained. Finally, advantages, disadvantages, potential and new direction in this chiral analysis field are highlighted.

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Thickness and composition determinations from T.E.M. specimens using both x-ray and backscattered electron data

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100112816 ◽

1984 ◽

Vol 42 ◽

pp. 576-577

Author(s):

M.D. Ball ◽

H. Lagace ◽

M.C. Thornton

Keyword(s):

Electron Microscope ◽

Atomic Number ◽

Transmission Electron Microscope ◽

Convenient Method ◽

Flow Chart ◽

X Ray ◽

Intensity Measurements ◽

Transmission Electron ◽

Electron Intensity ◽

Backscattered Electron

The backscattered electron coefficient η for transmission electron microscope specimens depends on both the atomic number Z and the thickness t. Hence for specimens of known atomic number, the thickness can be determined from backscattered electron coefficient measurements. This work describes a simple and convenient method of estimating the thickness and the corrected composition of areas of uncertain atomic number by combining x-ray microanalysis and backscattered electron intensity measurements.The method is best described in terms of the flow chart shown In Figure 1. Having selected a feature of interest, x-ray microanalysis data is recorded and used to estimate the composition. At this stage thickness corrections for absorption and fluorescence are not performed.

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Stereo imaging in the shadow electron microscope

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100107745 ◽

1978 ◽

Vol 36 (1) ◽

pp. 120-121

Author(s):

W. C. T. Dowell

Keyword(s):

Electron Microscopy ◽

Electron Microscope ◽

Convenient Method ◽

Patent Application ◽

Standard Technique ◽

Stereo Imaging ◽

Stereo Images ◽

Specimen Height

Stereo imaging is not new to electron microscopy. Von Ardenne, who first published transmission pairs nearly forty hears ago, himself refers to a patent application by Ruska in 1934. In the early days of the electron microscope von Ardenne employed a pair of magnetic lenses to view untilted specimens but soon opted for the now standard technique of tilting the specimen with respect to the beam.In the shadow electron microscope stereo images can, of course, be obtained by tilting the specimen between micrographs. This obvious method suffers from the disadvantage that the magnification is very sensitive to small changes in specimen height which accompany tilting in the less sophisticated stages and it is also time consuming. A more convenient method is provided by horizontally displacing the specimen between micrographs. The specimen is not tilted and the technique is both simple and rapid, stereo pairs being obtained in less than thirty seconds.

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Rotary Beveling for In Situ Thin-Section Microscopy of Cell Cultures

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100099192 ◽

1981 ◽

Vol 39 ◽

pp. 550-551

Author(s):

Dean A. Handley ◽

Jack T. Alexander ◽

Shu Chien

Keyword(s):

Cell Growth ◽

Cell Cultures ◽

Molecular Interactions ◽

Convenient Method ◽

Petri Dish ◽

Simple Method ◽

Thin Section Microscopy ◽

Thin Sectioning ◽

Organic Fluids

In situ preparation of cell cultures for ultrastructural investigations is a convenient method by which fixation, dehydration and embedment are carried out in the culture petri dish. The in situ method offers the advantage of preserving the native orientation of cell-cell interactions, junctional regions and overlapping configurations. In order to section after embedment, the petri dish is usually separated from the polymerized resin by either differential cryo-contraction or solvation in organic fluids. The remaining resin block must be re-embedded before sectioning. Although removal of the petri dish may not disrupt the native cellular geometry, it does sacrifice what is now recognized as an important characteristic of cell growth: cell-substratum molecular interactions. To preserve the topographic cell-substratum relationship, we developed a simple method of tapered rotary beveling to reduce the petri dish thickness to a dimension suitable for direct thin sectioning.

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