Prevention of insulin self-aggregation by a protic ionic liquid

Abstract

The self-aggregation and thermal instability of insulin (In) was considerably controlled in the presence of ammonium-based protic ionic liquids (PILs). The thermal stability of In in PILs was observed using fluorescence and absorption spectroscopy of the Tyr environment of the biomolecule. Additionally, from circular dichroism (CD) measurements, we observed the shift in the wavelength towards lower values in the presence of PILs, which indicates the formation of monomers of In, further evidently supported by dynamic light scattering (DLS) measurements. Surprisingly, it is the monomeric form of the In that exists in the active form. For the first time, ammonium-based PILs have been shown to be novel solvents for In, which prevent it from associating into an inactive form and also stabilizes In against thermal influence.