Herein, we have investigated the binding interaction of bovine serum albumin (BSA) with a series of 1-alkyl-3-methylimidazolium tetrafluoroborate (alkyl = ethyl, butyl, hexyl, and octyl) ionic liquids (ILs) in physiological buffer medium. The ILs are chosen basically to understand the effect of alkyl chain length on IL−protein interaction. Experiments have shown that the quenching of fluorescence of BSA is induced by relatively longer alkyl chain-containing ILs, [OMIM][BF 4 ] and [HMIM][BF 4 ]. The enthalpy-driven spontaneous binding (−ve ΔG) of hexyl and octyl chaincontaining ILs with the protein is mediated by both hydrogenbonding and van der Waals interactions. The experimental data have categorically explained the denaturation of protein conformation upon interaction with both [OMIM][BF 4 ] and [HMIM][BF 4 ]. The molecular docking calculation nicely corroborates the experimentally obtained results. The present study reveals that neither a smaller alkyl group-containing IL nor a very large alkyl group-containing IL is necessary to have effective protein−IL interactions. The study also reveals the influence of hydrophobic interaction over and above the hydrogen-bonding interaction on protein−IL binding events and essentially gives an idea about the optimum hydrophobic character of the ILs that is necessary to induce protein−IL interaction and consequently the denaturation of the protein structure.
With an objective to understand the differences in the behavior of monocationic and dicationic ionic liquids (ILs) in their interaction with protein, we have investigated the binding interaction of lysozyme enzyme with two monocation ionic liquids (MILs), [C 3 MIm][Br], [C 6 MIm][Br], and one dicationic ionic liquid (DIL), [C 6 (MIm) 2 ][Br] 2 , by exploiting various experimental methods. These ILs are purposefully chosen so that the effect of both hydrophobicity and structural arrangements of the cationic moiety of ionic liquids (ILs), if any, on the interaction event is understood. Both average ensemble and single molecule pathways have been adopted to obtain a comprehensive picture. For ensemble averaged measurements, the interaction events have been investigated by steady-state and time-resolved fluorescence spectroscopy, whereas for single molecule measurements, fluorescence correlation spectroscopy (FCS) has been utilized. Additionally, the behavior of protein in the absence and presence of ILs has also been investigated through circular dichroism (CD) measurements. The investigations have revealed that MILs and DIL interact differently with the protein. In particular, as compared to MILs, the influence of DIL toward protein is observed to be significantly less in terms of change in the structure and dynamics of protein. The outcome of the present work has demonstrated that imidazolium-based DIL can be a better choice over MILs for retaining native structure of protein in aqueous medium.
In recent times,
deep eutectic solvents (DESs) have emerged as
an environment-friendly alternative to both common organic solvents
and ionic liquids (ILs). The present study has been undertaken with
an objective to understand the intermolecular interaction, structural
organization, and dynamics of two DES systems in the absence and presence
of lithium salt so that the potential of these mixtures in electrochemical
application is realized. For this purpose, the steady-state, time-resolved
fluorescence, electron paramagnetic resonance (EPR), and nuclear magnetic
resonance (NMR) behavior of two DESs (ethaline and glyceline) and
their mixture with lithium bis(trifluoromethylsulfonyl) imide (LiNTf2) has been investigated. Measurements of polarity through
EPR technique have revealed that the polarities of DESs are close
to aliphatic polyhydroxy alcohol and the polarities of the medium
increase with the increase in lithium salt concentration. Studies
on solvation dynamics have indicated that there is an increase in
average solvation time with the increase in lithium salt concentration.
Investigation of rotational dynamics of some selected fluorophore
in these media has shown that addition of lithium salt significantly
alters the nano/microstructural organization of both DESs. Further,
measurements of the self-diffusion coefficient through NMR have also
supported the perturbation of the nanostructural organization of the
solvent systems by addition of lithium salts. Essentially, all of
these investigations have suggested that addition of lithium salt
significantly alters the microscopic behavior of DESs. The outcome
of this study is expected to be helpful in realizing the potential
of these media for various electrochemical applications including
application in lithium-ion battery.
The present study has been undertaken with an objective
to find
out a suitable medium for the long-term stability and storage of the ct-DNA structure in aqueous solution. For this purpose,
the potential of a pyrrolidinium-based dicationic ionic liquid (DIL)
in stabilizing ct-DNA structure has been investigated
by following the DNA–DIL interaction. Additionally, in order
to understand the fundamental aspects regarding the DNA–DIL
interaction in a comprehensive manner, studies are also done by employing
structurally similar monocationic ionic liquids (MILs). The investigations
have been carried out both at ensemble-average and single molecular
level by using various spectroscopic techniques. The molecular docking
study has also been performed to throw more light into the experimental
observations. The combined steady-state and time-resolved fluorescence,
fluorescence correlation spectroscopy, and circular dichroism measurements
have demonstrated that DILs can effectively be used as better storage
media for ct-DNA as compared to MILs. Investigations
have also shown that the extra electrostatic interaction between the
cationic head group of DIL and the phosphate backbone of DNA is primarily
responsible for providing better stabilization to ct-DNA, retaining its native structure in aqueous medium. The outcomes
of the present study are also expected to provide valuable insights
in designing new polycationic IL systems that can be used in nucleic
acid-based applications.
Herein, we first present synthesis, structures, luminescent properties, and electrochemistry of gold(III)‐N‐heterocyclic carbene (NHC) complexes fasten with 2,2′‐bipyridine (bpy) or 1,10′‐phenanthroline (phen). Starting from the proligand 3‐[pyridin‐3‐yl]imidazo[1,5‐a]pyridin‐4‐ylium hexafluorophosphate (1·HPF6), two novel complexes, namely, [Au(1)(bpy)Cl][PF6]2 (2) and [Au(1)2(phen)][PF6]3 (3), have been synthesized and characterized by several spectroscopic techniques. Finally, the solid‐state structures of 2, 3, and precursors [Au(bpy)Cl2][PF6] and [Au(phen)Cl2][PF6] have been determined by single‐crystal X‐ray diffraction studies. The absorption, emission, and lifetime properties of 2 and 3 have been compared with the precursors [Au(bpy)Cl2][PF6] and [Au(phen)Cl2][PF6] to observe the influence of NHC. Though the precursors [Au(bpy)Cl2][PF6] and [Au(phen)Cl2][PF6] are non‐luminescent, yet complexes 2 and 3 are luminescent. A combination of the chromophoric and π‐acid bpy/phen ligand in Au(III) complexes with the strong σ‐donor NHC ligand significantly enhanced the emission properties of the complexes. The blue emission of 2 and 3 in 390–500 nm regions has been tentatively ascribed to arise from intraligand and metal‐to‐ligand charge transfer (MLCT) transitions; also, partial contributions are expected from hydrogen‐bonding interactions. Cyclic voltammetric studies revealed Au(III) → Au(I) and Au(I) → Au(0) reductions at ~ −0.35 to ‐0.29 V and ~ −1.20 to ‐1.15 V, and the potentials are compared with precursors.
Although deep eutectic solvents (DESs) are regarded as useful substitutes for both ionic liquids and common organic solvents for storage and applications of biomolecules, it is still unclear whether all...
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.