Physicochemical investigation of antibacterial Moxifloxacin interacting with quaternary ammonium disinfectants

Abstract

The quaternary ammonium disinfectants (quats) offer exciting perspectives in biophysical research to mimic biomembranes at molecular level. In the present study, we carried out photo-luminescent measurements to probe the molecular interaction of potential antibacterial drug, Moxifloxacin (MOF) with conventional cationic quaternary ammonium surfactants viz., Cetrimonium bromide (HTAB) and Mecetronium bromide (EHDAB) under varying physiological conditions. The impact of surfactants’ microstructure on physicochemical properties of MOF was quantified with the help of mathematical models. By benefiting from the electrostatic interactive forces, larger and more hydrophobic head group of surfactant are found to favor the solubilization of MOF in the micellar corona. These findings were confirmed by measuring the binding capacity for the MOF-surfactants combinational system and the Stern–Volmer quenching constant (Ksv) values. The in-depth mechanism revealed that the binding mode in MOF-surfactants combinational system is spontaneous and the quenching exists in static mode initiated by ground-state complex formation. We believe that the true knowledge of host–guest interaction mechanisms concerning model membrane with entrapped fluorophore can help in better understanding of molecular recognition in related phospholipid membrane models.