Apparent molar volume, compressibility, and spectroscopic studies of ionic surfactants in aqueous solutions of antibiotic gemifloxacin

Abstract

This work aims to explore the interactions between a wide-spectrum bactericidal drug, gemifloxacin (GMF), and micelles of cationic (dodecyltrimethylammonium bromide, DTAB) and anionic (sodium dodecyl sulfate, SDS) surfactants at the molecular level under physiological conditions (using a phosphate buffer, pH 7.4). Various physical parameters are calculated from volumetric and acoustic data. These include apparent molar volume (${ɸ}_V$), apparent molar isentropic compressibility (${ɸ}_K$), isentropic compressibility ($K_s$), specific acoustic impedance (Z), relative association (RA), intermolecular free length (L_f) and sound velocity number (U). The obtained quantities are interpreted regarding of solute-solute and solute-solvent interactions employing the cosphere overlap model and electrostriction effect. Further, normal and differential UV-visible spectroscopy is employed to predict GMF locus in ionic micelles and to find the binding constant (K_b) and partition coefficient (K_c) along with the corresponding free energy changes of GMF-ionic micelle systems. The results demonstrate that the binding and partitioning of GMF with SDS is more significant than DTAB.

Graphical Abstract

Keywords:

• Gemifloxacin
• ionic surfactant
• electrostriction effect
• cosphere overlap model
• volumetric studies
• UV-visible spectroscopy

Additional information

Funding

The authors express gratitude to Higher Education Commission (HEC) of Pakistan for funding this research under HEC-NRPU Project No. 5475.