Temperature dependent micellar study of streptomycin sulfate in aqueous amino acid solutions: physicochemical approach.

An investigation has been carried out to gain insight of the micellization behavior of streptomycin sulfate, a surface-active drug, in aqueous medium for six amino acids (proline, glutamic acid, asparagine, glycine, histidine, and aspartic acid) at 0.01 mol·kg−1. The thermodynamic aspects were analyzed using three techniques: conductivity, density, and speed of sound measurements at various temperatures (293.15–313.15 K) along with UV–Vis spectroscopy at a specific temperature of 298.15 K. By employing conductometry, valuable data on micellization and the degree of ionization of the drug were obtained. The impact of amino acids on two essential parameters, the critical micellar concentration (CMC) and thermodynamic aspects of drug micellization, have been examined. Interestingly, the presence of amino acids was found to enhance the drug tendency to form micelles, as depicted by the CMC variations. The study also investigated the suitability of UV–Vis spectroscopy with pyrene as a probe to explore the interactions between amino acids and the drug. Further, density and speed of sound analysis provides information about strong interactions in streptomycin sulfate-amino acids-water system. The results revealed significant changes in the micropolarity and micelle assembly due to these interactions in aforesaid system. [ABSTRACT FROM AUTHOR]