Unveiling the Influence of Non-Toxic Fluorinated Ionic Liquids Aqueous Solutions in the Encapsulation and Stability of Lysozyme

Abstract

Proteins are bioactive compounds with high potential to be applied in the biopharmaceutical industry, food science and as biocatalysts. However, protein stability is very difficult to maintain outside of the native environment, which hinders their applications. Fluorinated ionic liquids (FILs) are a promising family of surface-active ionic liquids (SAILs) that have an amphiphilic behavior and the ability to self-aggregate in aqueous solutions by the formation of colloidal systems. In this work, the protein lysozyme was selected to infer on the influence of FILs in its stability and activity. Then, the cytotoxicity of FILs was determined to evaluate their biocompatibility, concluding that the selected compounds have neglected cytotoxicity. Therefore, UV–visible spectroscopy was used to infer the FIL-lysozyme interactions, concluding that the predominant interaction is the encapsulation of the lysozyme by FILs. The encapsulation efficiency was also tested, which highly depends on the concentration and anion of FIL. Finally, the bioactivity and thermal stability of lysozyme were evaluated, and the encapsulated lysozyme keeps its activity and thermal stability, concluding that FILs can be a potential stabilizer to be used in protein-based delivery systems.

Disclosing the Potential of Fluorinated Ionic Liquids as Interferon-Alpha 2b Delivery Systems

“…These results also indicate that [C 2 C 1 Im] + and [N 1112(OH) ] + cations present similar behaviour, supporting the anion having the most important role in this interaction. Comparing these results with the ones obtained for lysozyme [ 40 ], the protein-FILs interactions have high specificity and depend on the target protein. In this case, there were no significant alterations in the characteristic peak of IFN-α 2b, and the studied solutions do not present turbidity.…”

“…To understand the impact of different simulated biological fluids, protein medium, and IFN-α 2b on the aggregation behaviour of FILs, the [C 2 C 1 Im][C 4 F 9 SO 3 ] was selected. This FIL has aggregates very well characterized in pure water [ 38 ] and with other biomolecules, such as BSA and lysozyme [ 40 , 41 , 42 , 43 ]. One way to acquire this information is through the careful analysis of the FIL conductivity profile, which is dependent on the FIL concentration.…”

“…Thus, the IFN-α 2b absorption spectrum is very similar to that of most proteins, with a characteristic band between 260 and 300 nm. Any alteration on the profile of this band may indicate a perturbation of the protein chromophores, and consequently, the existence of an interaction with a ligand [ 40 ]. For example, the coverage of the protein surface by the FIL can be reflected in the absorption spectra by the absence of the characteristic absorption band or reflected in the turbidity of the solution due to the presence of protein-FIL aggregates [ 40 ].…”

“…This superior surfactant behaviour allows those FILs to be completely miscible in aqueous solutions [ 38 ]. Moreover, FILs can be customized to have negligible cytotoxicity in four different human cell lines [ 31 , 32 , 39 , 40 ], high acceptance of red blood lysis [ 32 ], and insignificant ecotoxicity to several aquatic species and bacteria [ 31 , 32 ]. These properties have been key to considering the use of FILs in the biological field, especially in the formulation of DDSs for therapeutic proteins.…”

“…Vieira et al [ 42 ] have demonstrated that after the encapsulation of lysozyme by FILs, the system is stable and the protein can be later released with the application of external stimuli, maintaining the properties of the protein intact. Ferreira et al [ 40 ] have also successfully encapsulated lysozyme with hydroxyl functionalized FILs (more biocompatible compounds), keeping the activity of this protein. Alves et al [ 43 ] also studied the impact of FILs on the stability, structure, and interactions of bovine serum albumin (BSA).…”