Interaction of cephalexin monohydrate with surfactants in aqueous and sodium chloride solution at variable temperatures: Conductivity and spectroscopic measurements

Cephalexin monohydrate (CLM) is a well-known antibiotic applied for prohibiting bacterial growth. Herein, the mode of interaction of CLMwith both ionic (cetyltrimethylammonium bromide (CTAB) and sodium dodecyl sulfate (SDS)), and nonionic (triton X-100 (TX-100)) surfactants, was investigated using the conductivity measurement and UV-Visible spectroscopic techniques in H(2)Oand NaCl+ H2O media at numerous temperatures ranging from 293.15 to 328.15 K. In the current study, the critical micelle concentration (CMC) of CLM + CTAB and CLM+ SDS mixed systems was estimated from a sudden and clear breakpoint of specific conductivity (kappa) versus the concentration of surfactant plot. A single CMC was found for both CLM + CTAB and CLM + SDS systems in entirely experimental cases studied. The value of CMC of surfactants undergoes a drop in presence of CLM in an aqueous phase and hence, the drug causes an enhancement of the extent of micellization of surfactants. Also, the CMC values of CLM + CTAB and CLM + SDS mixed systems were found to reduce in NaCl + H(2)Omedium and the CMC values were observed to experience a further reduction with increasing concentration of NaCl salt. A negative standard free energy change (Delta G(m)(o)) ofmicellization discloses that the CLM+ ionic surfactant micellization is spontaneous. The different thermodynamic parameters of transfer and the enthalpy-entropy compensation parameters of micelle formation were also measured and demonstrated appropriately. The binding constant (K-b) of the CLM+ TX-100 mixture has been evaluated fromthe Benesi-Hildebrand equation and the values were found to be dependent on CLM concentration and temperature. The Delta H-b(o) and Delta S-b(o) values of CLM+ TX-100 mixture reveal the survival of the electrostatic force of interaction along with the presence of hydrophobic interaction developed between the CLM drug and TX-100 surfactant. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

The study investigated the interaction mode and micellization characteristics of Cephalexin monohydrate with both ionic and nonionic surfactants, revealing that the presence of CLM enhances the micellization of surfactants. The study also found that the binding constant of CLM mixture with nonionic surfactant is dependent on CLM concentration and temperature, indicating the presence of electrostatic and hydrophobic interactions between the CLM drug and the surfactant.