Antimicrobial Colloidal Complexes of Lysozyme with Bio-Based Surface Active Ionic Liquids in Aqueous Medium

Abstract

Bio-based surface-active ionic liquids (SAILs) have been synthesized and investigated for their complexation with lysozyme (LYZ) in an aqueous medium to develop antimicrobial SAIL−LYZ colloidal complexes. The synthesized SAILs, [Cho]-[Sar] and [Cho][Doc], are comprised of choline ([Cho] + ) and lauryl sarcosinate ([Sar] − ) or deoxycholate ([Doc] − ). The constituent anions of the investigated SAILs are structurally dissimilar and thus resulted in contrasting complexation behavior toward LYZ, as suggested by the results obtained from different techniques. The interfacial behavior is monitored using tensiometry. Zeta-potential, turbidity, and dynamic light scattering results provide insights into the complexation phenomenon in bulk. The observations made from fluorescence and circular dichroism (CD) spectroscopy give information about the alterations in the inherent structure of LYZ. The thermodynamics of the binding of SAILs with LYZ is monitored using isothermal titration calorimetry (ITC). Computer simulations have been utilized to determine the preferential binding site of SAILs on LYZ, which supports the results obtained from different techniques. Interestingly, LYZ complexed with the investigated SAILs, which are nonantimicrobial, is found to exhibit enhanced antimicrobial activity depending upon the concentration regime of the used SAIL. In this way, we have developed new antimicrobial colloidal complexes of SAILs and LYZ. The present study provides useful insights to synthesize new bio-based SAILs to be utilized for creating colloidal formulations applicable in enzyme/protein stabilization, storage, and other biomedical applications.

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

“…Lysozyme (Lys) is a small globular protein with 129 amino acid residues, a molecular weight of approximately 14.7 kDa, and a positively charged surface, found in different living organisms and biological fluids. Lys is an enzyme with multifaceted properties which enable its unique antibacterial, antifungal, anti-inflammatory, antitumor, and antihistaminic activities [6,7]. This enzyme was selected for this study as a model protein due to its vast applicability in biochemical, pharmaceutical, and food industry fields; easy availability due to the high homology of human Lys with hen egg white Lys; and irreversible aggregation which hinders its usage and increases the interest in it as a target of studies in the areas of protein stability, activity, interactions with other compounds, protein-based deliveries, crystallization, and separation processes [6,7].…”

“…A specific family has grown in this direction, the surface-active ionic liquids (SAILs), which are characterized by their enhanced solubilization mechanisms due to their amphiphilic nature granted by the long cationic and/or anionic hydrogenated chains. The superior surface activity of SAILs compared with conventional surfactants allows self-assembly in aqueous solutions into more efficient colloidal systems, such as micelles or vesicles, with greater control of their shape, size, stability, and specific utility [7,[10][11][12][13][14][15][16]. These advantages highlight the substitution of surfactants by SAILs in the protein stability field, successfully demonstrated by some works in the specific case of lysozyme.…”

“…They found out that this IL is an efficient additive agent for the enhancement of lysozyme stability, increasing its activity and preserving the thermal and conformational stability, while the other studied IL has the opposite behavior. Singh et al [7,16] recently showed in two different works the complexation of lysozyme by binding to bio-based SAILs, allowing the connection of lysozyme molecules to each other and providing enhanced structural stability and antimicrobial activity to the enzyme, depending on the concentration of SAILs and of their distinct interactions with the protein.…”

Scrutinizing Self-Assembly, Surface Activity and Aggregation Behavior of Mixtures of Imidazolium Based Ionic Liquids and Surfactants: A Comprehensive Review

“…Their cationic or anionic part possesses a charged head group and a long hydrophobic tail in it. This is responsible for the self-aggregation property and surface activity of SAILs (Cobanov et al, 2020 ; Garcia et al, 2020 ; Singh et al, 2020 ; Alves et al, 2021 ). There is no hardliner difference among SAILs and surfactants.…”

Recent Advances in Ionic Liquids in Biomedicine

“…[ 173 , 174 ] Recently they have been both used alone [ 175 , 176 , 177 , 178 , 179 , 180 , 181 , 182 ] and incorporated into hybrid materials. [ 183 , 184 , 185 , 186 , 187 , 188 , 189 , 190 ] In particular, poly(ionic liquids) have recently shown excellent antibacterial properties [ 191 , 192 , 193 , 194 , 195 , 196 , 197 , 198 , 199 ] and their polymeric character has been used to manufacture antibacterial membranes. [ 200 , 201 ] There are two main proposed mechanisms of action for ionic liquid bactericidal activity.…”