Effect of salts and temperature on the interaction of levofloxacin hemihydrate drug with cetyltrimethylammonium bromide: Conductometric and molecular dynamics investigations

Investigation of the interaction of the beta-lactum antibiotic drug levofloxacin hemihydrate (LFH) with cetyltrimethylammonium bromide (CTAB) has been performed in aqueous solution and in the attendance of salts at various temperatures (298.15, 303.15, 308.15, 313.15 and 318.15 K). A single critical micelle concentration (CMC) was observed for pure CTAB and their mixture with the drug (LFH). The CMC values for mixed systems (LFH + CTAB) in the presence of salt showed lower in magnitude in comparison to their absence. This pointed out the early micellization of the mixture of LFH and CTAB. All the Delta G(m)(0) values were found to be negative for all systems. The Delta H-m(0) and Delta S-m(0) values showed that hydrophobic and electrostatic interactions were boosted in the presence of salts compared to their absence at lower and higher temperatures respectively. The other thermodynamic parameters such as transfer energy (Delta G(m,tr)(0).), transfer enthalpy (Delta H-m,tr(0).) as well as transfer entropy (Delta S-m,tr(0).) were also determined and discussed in detail. The intrinsic enthalpy gain (Delta H-m(0,)*) and the compensation temperature (T-c) were also evaluated and discussed. Molecular dynamics simulation reveals that aqueous as well as salt environment have impact on the hydrophobic interaction between LFH and surfactant. (C) 2017 Elsevier B.V. All rights reserved.