Physicochemical and DFT insights into streptomycin sulfate and cetrimonium bromide interactions

Electrical conductivity measurements at 298.15 K were conducted to study the formation of mixed micelles with the antibiotic streptomycin sulfate (SMS) and the cationic surfactant cetrimonium bromide (CB) at various mole fraction (α₁) of SMS. It was observed that the critical micelle concentration (cmc) values decreased in the mixed system, with experimental cmc values being lower than the ideal cmc values (cmc*), indicating non-ideal behavior. We used theoretical models from Clint, Rubingh, Motomura, and Rodenas to analyze micellar mole fractions (X_i) and activity coefficients (f_i). The interaction parameter (β) calculated via Rubingh’s model revealed a synergistic effect, attributed to hydrophobic interactions between the drug and surfactant. Thermodynamic parameters confirmed that mixed micellization is spontaneous and more stable than individual micelles. Additionally, computational simulations helped optimize our molecules, enhancing our understanding of drug-surfactant interactions. This study underscores the significance of electrical conductivity measurements and density functional theory (DFT) in examining drug behavior in the presence of surfactant.