Pseudo-zwitterionic microvesicles for sustained urea release

Abstract

Zwitterionic microvesicles formed by catanionic system, based on sodium dodecyl sulfate and hexadecyltrimethyl ammonium bromide, have been investigated for sustained urea release using UV–visible absorption spectroscopy. The change in variables such as temperature, sonication time and initial urea concentration was related to urea entrapment efficiency and release from microvesicles. Korsmeyer–Peppas model was applied to highlight release mechanism and kinetics. Both diffusion and erosion were responsible for urea release and rate constant varied with change in conditions. The quantification of association between urea and catanionic vesicles in terms of binding constant (Kbin) and binding free energy showed that urea binding was thermodynamically favored. Our results indicate that biocompatible pseudo-zwitterionic vesicles have enormous potential to act as sustained release system for nitrogenous fertilizers such as urea.

Keywords

• controlled-release
• surfactant vesicles
• fertilizer