Spectroscopic and thermodynamic studies on binding behaviour of an ionic liquid, 2′,3′-Epoxypropyl-N-methyl-2-oxopyrrolidinium acetate, with bovine serum albumin (BSA)

Abstract

Spectroscopic and thermodynamic investigation of molecular interactions in a binary mixture of 2′,3′-epoxypropyl-N-methyl-2-oxopyrrolidinium acetate ([EPMpyr][OAC]) ionic liquid (IL) with a bovine serum albumin (BSA) aqueous solution was carried out. The thermophysical properties of density (ρ) and speed of sound (u) were first measured for the binary mixture at different mole concentrations in the temperature range from 293.15–323.15 K at a 5 K interval at atmospheric pressure. Using the above data, the thermodynamic properties of excess molar volume (VmE), isentropic compressibility (ks), deviation in isentropic compressibility Δks and intermolecular free length Lf were derived. These thermodynamic parameters have been used to get more information about the interaction of IL with BSA. In addition, absorption, steady state emission, synchronous emission, three-dimensional (3D) emission and circular dichroism (CD) have been exploited to acquire an understanding of the binding mechanisms and binding strengths of the interactions between the IL and BSA. Emission quenching results clearly indicate that the effect of IL on trypthophan of BSA. This work was undertaken with the expectation of getting results which would cast light on the types of interactions occurring between [EPMpyr][OAC] and BSA molecule. Furthermore, the data emanating from this work may help researchers in the bio-pharmaceutical sector developing more active IL based drugs. Moreover, this work can provide valuable information of potential interest to researchers in biotechnology including drug bioengineering.