Self-assembly of mixed systems based on nonionic and carbamate-bearing cationic surfactants as a tool for fabrication of biocompatible nanocontainers

Aggregation behavior of mixed micellar solutions and microemulsions based on cationic carbamate-bearing surfactants with hexadecyl hydrophobic group and nonionic surfactants (Tween 80, Tween 20, and Triton X 100) has been studied. Critical micelle concentrations have been determined at varying component ratios, which demonstrated a negative deviation of surfactant systems from ideal behavior (synergetic effect). The electrokinetic potential and size of aggregates have been evaluated. Solubilizing effect of individual and mixed systems toward anti-inflammatory drug meloxicam possessing pH dependent solubility in aqueous solutions has been testified by spectrophotometry. It has been determined that nonionic surfactants slightly increase the solubility of meloxicam in water, while the carbamate-bearing surfactants with the concentration of nearly 0.1% provide more than a 10-fold increase in the solubility of this drug in weakly acidic media. Carbamate-bearing surfactants are referred to a class of moderately toxic substances. Their employment in binary compositions with nonionic surfactants has decreased the toxicity of the systems with the retention of the high degree of solubilizing effect. A transition to biocompatible Tween 80/oleic acid/water/ethyl alcohol microemulsions modified with carbamate-bearing surfactant additives has increased the solubility of meloxicam by the factor of 575 as compared to water.