Supramolecular Systems Based on Dicationic Gemini Surfactants: Aggregation Behavior and Prospects for Developing Multifunctional Nanocarriers for Antidiabetic Drug Delivery

The aggregation behavior, solubilization capacity, and antimicrobial activity of ethylammonium gemini surfactants with varying spacer lengths, C12CsC12(Et) (s = 4, 6, 8), and their piperidinium analogue C12C4C12(Pip), were investigated systematically. The critical micelle concentrations (CMC), counterion binding degrees, adsorption and thermodynamic parameters, aggregation numbers, and hydrodynamic diameters of the micelles were determined using tensiometry, conductometry, spectrophotometry, and dynamic light scattering. The results showed that increasing the spacer length had only a minor effect on the CMC values but significantly enhanced the micellar solubilization of the hydrophobic compounds, including the dye Orange OT and the hypoglycemic drug glipizide. The lead compound, C12C8C12(Et), at a concentration of 7.0 mM, increased the aqueous solubility of glipizide by more than 20-fold. Antimicrobial activity assays against various pathogenic bacteria (B. cereus, E. faecalis, E. coli, and P. aeruginosa) and fungi (T. mentagrophytes and C. albicans) demonstrated minimum inhibitory concentrations in the micromolar range, which is comparable to those of commercially available drugs. The combination of high solubilization capacity with pronounced antimicrobial activity highlights the potential of these dicationic gemini surfactants as multifunctional nanocontainers for the delivery of poorly soluble drugs. Additionally, variations in the spacer length and the transition from acyclic to cyclic head groups offer opportunities to fine-tune the practical properties of these systems for specific applications.