scholarly journals Peek Inside the Water Mixtures of Ionic Liquids at Molecular Level: Microscopic Properties Probed by EPR Spectroscopy

2021 ◽  
Vol 22 (21) ◽  
pp. 11900
Author(s):  
Mikhail Yu. Ivanov ◽  
Yuliya F. Polienko ◽  
Igor A. Kirilyuk ◽  
Sergey A. Prikhod’ko ◽  
Nicolay Yu. Adonin ◽  
...  

Many ionic liquids (ILs) can be mixed with water, forming either true solutions or emulsions. This favors their applications in many respects, but at the same time might strongly alter their physicochemical properties. A number of methods exist for studying the macroscopic properties of such mixtures, whereas understanding their characteristics at micro/nanoscale is rather challenging. In this work we investigate microscopic properties, such as viscosity and local structuring, in binary water mixtures of IL [Bmim]BF4 in liquid and glassy states. For this sake, we use continuous wave and pulse electron paramagnetic resonance (EPR) spectroscopy with dedicated spin probes, located preferably in IL-rich domains or distributed in IL- and water-rich domains. We demonstrate that the glassy-state nanostructuring of IL-rich domains is very similar to that in neat ILs. At the same time, in liquid state the residual water makes local viscosity in IL-rich domains noticeably different compared to neat ILs, even though the overwhelming amount of water is contained in water-rich domains. These results have to be taken into account in various applications of IL-water mixtures, especially in those cases demanding the combinations of optimum micro- and macroscopic characteristics.

Pharmaceutics ◽  
2021 ◽  
Vol 13 (10) ◽  
pp. 1661
Author(s):  
Niuosha Sanaeifar ◽  
Karsten Mäder ◽  
Dariush Hinderberger

This investigation aimed at developing BSA hydrogels as a controlled release system to study the release behavior of spin-labeled coumarin-3-carboxylic acid (SL-CCS) and warfarin (SL-WFR). The release profiles of these spin-labeled (SL-) pharmaceuticals from BSA hydrogels prepared with different procedures are compared in detail. The mechanical properties of the gels during formation and release were studied via rheology, while a nanoscopic view on the release behavior was achieved by analyzing SL-drugs–BSA interaction using continuous wave electron paramagnetic resonance (CW EPR) spectroscopy. The influence of type of drug, drug concentration, duration of gel formation, and gelation methods on release behavior were characterized by CW EPR spectroscopy, EPR imaging (EPRI), and dynamic light scattering (DLS), which provide information on the interaction of BSA with SL-drugs, the percentage of drug inside the hydrogel and the nature and size of the released structures, respectively. We found that the release rate of SL-CCS and SL-WFR from BSA hydrogels is tunable through drug ratios, hydrogel incubation time and gelation procedures. All of the results indicate that BSA hydrogels can be potentially exploited in controlled drug delivery applications.


2017 ◽  
Vol 231 (4) ◽  
Author(s):  
Andrey A. Kuzhelev ◽  
Victor M. Tormyshev ◽  
Olga Yu. Rogozhnikova ◽  
Dmitry V. Trukhin ◽  
Tatiana I. Troitskaya ◽  
...  

AbstractTriarylmethyl (TAM) radicals are widely used in electron paramagnetic resonance (EPR) spectroscopy as spin labels and in EPR imaging as spin probes for


Author(s):  
Jacob N. Spencer ◽  
Andrea Folli ◽  
Hong Ren ◽  
Damien M. Murphy

Continuous Wave (CW) Electron Paramagnetic Resonance (EPR) spectroscopy was used to study the defect structure and electron transfer mechanism in a series of LiBO2-V2O5 mixed conductive glasses of varying V2O5...


2021 ◽  
Author(s):  
Mikhail Yu. Ivanov ◽  
Olga D. Bakulina ◽  
Dmitriy Alimov ◽  
Sergey Aleksandrovich Prikhod'ko ◽  
Sergey L. Veber ◽  
...  

Intriguing heterogeneities and nanostructural reorganizations of glassy ionic liquids (ILs) have recently been found using electron paramagnetic resonance (EPR) spectroscopy. Alkyl chains of IL cations play the key role in...


Author(s):  
Igor Tkach ◽  
Ulf Diederichsen ◽  
Marina Bennati

AbstractElectron paramagnetic resonance (EPR)-based pulsed dipolar spectroscopy measures the dipolar interaction between paramagnetic centers that are separated by distances in the range of about 1.5–10 nm. Its application to transmembrane (TM) peptides in combination with modern spin labelling techniques provides a valuable tool to study peptide-to-lipid interactions at a molecular level, which permits access to key parameters characterizing the structural adaptation of model peptides incorporated in natural membranes. In this mini-review, we summarize our approach for distance and orientation measurements in lipid environment using novel semi-rigid TOPP [4-(3,3,5,5-tetramethyl-2,6-dioxo-4-oxylpiperazin-1-yl)-L-phenylglycine] labels specifically designed for incorporation in TM peptides. TOPP labels can report single peak distance distributions with sub-angstrom resolution, thus offering new capabilities for a variety of TM peptide investigations, such as monitoring of various helix conformations or measuring of tilt angles in membranes. Graphical Abstract


Biochemistry ◽  
2014 ◽  
Vol 53 (50) ◽  
pp. 7914-7928 ◽  
Author(s):  
Paul H. Oyala ◽  
Troy A. Stich ◽  
Jamie A. Stull ◽  
Fangting Yu ◽  
Vincent L. Pecoraro ◽  
...  

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