scholarly journals Footprints of Nanoscale DNA–Silver Cluster Chromophores via Activated-Electron Photodetachment Mass Spectrometry

ACS Nano ◽  
2019 ◽  
Vol 13 (12) ◽  
pp. 14070-14079 ◽  
Author(s):  
Molly S. Blevins ◽  
Dahye Kim ◽  
Christopher M. Crittenden ◽  
Soonwoo Hong ◽  
Hsin-Chih Yeh ◽  
...  
The Analyst ◽  
2019 ◽  
Vol 144 (11) ◽  
pp. 3518-3524 ◽  
Author(s):  
Dababrata Paul ◽  
Adrien Marchand ◽  
Daniela Verga ◽  
Marie-Paule Teulade-Fichou ◽  
Sophie Bombard ◽  
...  

Tandem mass spectrometry: native top-down sequencing by electron photodetachment dissociation (EPD) reveals ligand binding sites on DNA G-quadruplexes.


2019 ◽  
Author(s):  
Dababrata Paul ◽  
Adrien Marchand ◽  
Daniela Verga ◽  
Marie-Paule Teulade-Fichou ◽  
Sophie Bombard ◽  
...  

ABSTRACTMass spectrometry provides exquisite detail on ligand and cation binding stoichiometries with a DNA target. The next important step is to develop reliable methods to determine the cation and ligand binding sites in each complex separated by the mass spectrometer. To circumvent the caveat of ligand derivatization for cross-linking, which may alter the ligand binding mode, we explored a tandem mass spectrometry (MS/MS) method that does not require ligand derivatization, and is therefore also applicable to localize metal cations. By obtaining more negative charge states for the complexes using supercharging agents, and by creating radical ions by electron photodetachment, oligonucleotide bonds become weaker than the DNA-cation or DNA-ligand noncovalent bonds upon collision-induced dissociation of the radicals. This electron photodetachment (EPD) method allows to locate the binding regions of cations and ligands by top-down sequencing of the oligonucleotide target. The very potent G-quadruplex ligands 360A and PhenDC3 were found to replace a potassium cation and bind close to the central loop of 4-repeat human telomeric sequences.


2017 ◽  
Vol 121 (24) ◽  
pp. 13421-13427 ◽  
Author(s):  
Ananya Baksi ◽  
Atanu Ghosh ◽  
Sathish Kumar Mudedla ◽  
Papri Chakraborty ◽  
Shridevi Bhat ◽  
...  

2019 ◽  
Vol 91 (7) ◽  
pp. 4672-4679 ◽  
Author(s):  
Christopher M. Crittenden ◽  
Edwin E. Escobar ◽  
Peggy E. Williams ◽  
James D. Sanders ◽  
Jennifer S. Brodbelt

Author(s):  
Philippe Fragu

The identification, localization and quantification of intracellular chemical elements is an area of scientific endeavour which has not ceased to develop over the past 30 years. Secondary Ion Mass Spectrometry (SIMS) microscopy is widely used for elemental localization problems in geochemistry, metallurgy and electronics. Although the first commercial instruments were available in 1968, biological applications have been gradual as investigators have systematically examined the potential source of artefacts inherent in the method and sought to develop strategies for the analysis of soft biological material with a lateral resolution equivalent to that of the light microscope. In 1992, the prospects offered by this technique are even more encouraging as prototypes of new ion probes appear capable of achieving the ultimate goal, namely the quantitative analysis of micron and submicron regions. The purpose of this review is to underline the requirements for biomedical applications of SIMS microscopy.Sample preparation methodology should preserve both the structural and the chemical integrity of the tissue.


Author(s):  
K.K. Soni ◽  
D.B. Williams ◽  
J.M. Chabala ◽  
R. Levi-Setti ◽  
D.E. Newbury

In contrast to the inability of x-ray microanalysis to detect Li, secondary ion mass spectrometry (SIMS) generates a very strong Li+ signal. The latter’s potential was recently exploited by Williams et al. in the study of binary Al-Li alloys. The present study of Al-Li-Cu was done using the high resolution scanning ion microprobe (SIM) at the University of Chicago (UC). The UC SIM employs a 40 keV, ∼70 nm diameter Ga+ probe extracted from a liquid Ga source, which is scanned over areas smaller than 160×160 μm2 using a 512×512 raster. During this experiment, the sample was held at 2 × 10-8 torr.In the Al-Li-Cu system, two phases of major importance are T1 and T2, with nominal compositions of Al2LiCu and Al6Li3Cu respectively. In commercial alloys, T1 develops a plate-like structure with a thickness <∼2 nm and is therefore inaccessible to conventional microanalytical techniques. T2 is the equilibrium phase with apparent icosahedral symmetry and its presence is undesirable in industrial alloys.


Author(s):  
Bruno Schueler ◽  
Robert W. Odom

Time-of-flight secondary ion mass spectrometry (TOF-SIMS) provides unique capabilities for elemental and molecular compositional analysis of a wide variety of surfaces. This relatively new technique is finding increasing applications in analyses concerned with determining the chemical composition of various polymer surfaces, identifying the composition of organic and inorganic residues on surfaces and the localization of molecular or structurally significant secondary ions signals from biological tissues. TOF-SIMS analyses are typically performed under low primary ion dose (static SIMS) conditions and hence the secondary ions formed often contain significant structural information.This paper will present an overview of current TOF-SIMS instrumentation with particular emphasis on the stigmatic imaging ion microscope developed in the authors’ laboratory. This discussion will be followed by a presentation of several useful applications of the technique for the characterization of polymer surfaces and biological tissues specimens. Particular attention in these applications will focus on how the analytical problem impacts the performance requirements of the mass spectrometer and vice-versa.


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