Insights into the interaction of Bovine Serum Albumin with Surface-Active Ionic Liquids in aqueous solution

The unique physicochemical properties of Ionic liquids (ILs) make them very desirable for biomedical applications, namely as surface active ionic liquids (SAILs). SAILs surface activity, intrinsically higher than conventional surfactants, allows them to enhance drug permeability across biomembranes and, thus, become better drug carriers than current solutions. To harvest the full potential of these materials, in-depth studies of ILs interactions with model proteins are necessary to understand the mechanisms controlling these biological processes. Albumin, a key protein of blood serum, is of particular relevance, namely in drug carrier applications. Thus, here we characterize the interaction of bovine serum albumin (BSA) with fluorinated ionic liquids which are SAILs that possess fluorous tags equal to or longer than four carbon atoms. Their impact on BSA stability and structure was evaluated using different biophysical techniques. Differential scanning fluorimetry (DSF) and calorimetry (DSC), as well as circular dichroism (CD), yielded insights on the stabilization and secondary structure of BSA upon incubation with the ILs. Binding dynamics of the interaction were studied by conductimetry and isothermal titration calorimetry (ITC), which give the values of critical aggregation concentration (CAC) of the BSA-IL complex formation, as well as thermodynamic parameters. The results presented herein support the hypothesis that BSA is stabilized and encapsulated in the presence of FILs. Thus, the FILs studied in this work have potential for uses in biomedical applications.