Biophysical probing of antibacterial Gemifloxacin assimilated in surfactant mediated molecular assemblies

Abstract

The quaternary ammonium surfactants (Quats) are advantageously chosen disinfectants, which offer exciting perspectives in biophysical research to mimic biomembranes at molecular level. In this study, we investigated the extent of interactions of Gemifloxacin (GMF), an antibacterial drug, with conventional cationic surfactants, Cetrimonium bromide (HTAB) and Mecetronium bromide (EHDAB) under physiological conditions. The effect of cationic micelles on physicochemical and spectral properties of GMF was examined via photo-luminescent measurements. The quantification of GMF molecules entrapped by cationic micellar systems has been estimated with the help of mathematical models. Binding parameters and related free energies associated with each surfactant was calculated using differential spectroscopic method and fluorescence quenching mechanism. By benefiting from the electrostatic intermolecular forces, larger and more hydrophobic head group viz., EHDAB and HTAB are found to favors the solubilization of GMF in the outer region of the micellar interior. These findings have been confirmed by binding capacity for the GMF-surfactant combinational system and Stern–Volmer quenching constant (Ksv) values. Further evidence revealed that the binding is spontaneous in nature and the quenching mechanism could be ascribed to the static quenching mode initiated by ground-state complex formation.