Synergistic interaction and antibacterial properties of surface-active mono- and di-cationic ionic liquids with ciprofloxacin

The pharmaceutical industry has been experiencing various challenges while developing drugs, particularly concerning drug stability, solubility, and biocompatibility. Among these the poor solubility of drugs stands out as a serious issue, leading to reduced bioavailability and therapeutic efficiency. An effective approach to tackle these problems involves the utilization of surface-active compounds. Surface-active ionic liquids (SAILs) serve as a better choice for interacting with hydrophobic drugs and act as drug carriers. While the literature extensively discusses the interaction of drugs with monocationic ionic liquids, studies on dicationic ionic liquids are limited. Hence, we synthesized methyl imidazolium and vinyl imidazolium-based monocationic and dicationic surface-active ionic liquids and explored their interaction with ciprofloxacin (CIP), a hydrophobic drug. The evaluation of the aggregation behavior of these SAILs in the presence and absence of CIP was carried out using conductivity, dynamic light scattering, and zeta potential measurements in aqueous solutions. The interaction between SAILs and CIP was investigated using fluorescence spectroscopy. Our findings indicate that the critical micellar concentration of SAILs decreases in the presence of CIP, suggesting an interaction between the two. Also, the association constant and Gibbs free energy for complexation between SAIL and CIP was found to be negative which suggests that the complex formation between SAIL and CIP is spontaneous. Furthermore, we assessed the antibacterial activity of CIP in the presence and absence of SAILs by determining the MIC value. The results demonstrate an enhancement in the antibacterial efficacy of CIP in the presence of SAILs.