Modulation of Insulin Amyloid Fibrillization in Imidazolium-Based Ionic Liquids with Hofmeister Series Anions
Journal
International Journal of Molecular Sciences
Journal Volume
24
Journal Issue
11
Date Issued
2023-06-01
Author(s)
Vanik, Vladimir
Bednarikova, Zuzana
Fabriciova, Gabriela
Gazova, Zuzana
Fedunova, Diana
Abstract
Amyloid fibrils have immense potential to become the basis of modern biomaterials. The formation of amyloid fibrils in vitro strongly depends on the solvent properties. Ionic liquids (ILs), alternative solvents with tunable properties, have been shown to modulate amyloid fibrillization. In this work, we studied the impact of five ILs with 1-ethyl-3-methylimidazolium cation [EMIM+] and anions of Hofmeisterseries hydrogen sulfate [HSO4−], acetate [AC−], chloride [Cl−], nitrate [NO3−], and tetrafluoroborate [BF4−] on the kinetics of insulin fibrillization and morphology, and the structure of insulin fibrils when applying fluorescence spectroscopy, AFM and ATR-FTIR spectroscopy. We found that the studied ILs were able to speed up the fibrillization process in an anion- and IL-concentration-dependent manner. At an IL concentration of 100 mM, the efficiency of the anions at promoting insulin amyloid fibrillization followed the reverse Hofmeister series, indicating the direct binding of ions with the protein surface. At a concentration of 25 mM, fibrils with different morphologies were formed, yet with similar secondary structure content. Moreover, no correlation with the Hofmeister ranking was detected for kinetics parameters. IL with the kosmotropic strongly hydrated [HSO4−] anion induced the formation of large amyloid fibril clusters, while the other kosmotropic anion [AC−] along with [Cl−] led to the formation of fibrils with similar needle-like morphologies to those formed in the IL-free solvent. The presence of the ILs with the chaotropic anions [NO3−] and [BF4−] resulted in longer laterally associated fibrils. The effect of the selected ILs was driven by a sensitive balance and interplay between specific protein–ion and ion–water interactions and non-specific long-range electrostatic shielding.
Subjects
amyloid aggregation | amyloid fibril morphology | Hofmeister series | ionic liquids
SDGs
Type
journal article