Sulfited Tannin Capsules: Novel Stimuli-Responsive Delivery Systems

Microcapsules of sulfited Acacia mearnsii tannin (AmST-MCs) were generated for the first time via the sonochemical method. Their stability profile was assessed and set in the general context of tannin microcapsules (TMCs) generated under the same experimental conditions. The analytical data gathered in this work indicate an excellent stability of TMCs over time as well as under high temperature and pressure, which is a major milestone toward the meaningful applications of TMCs in industrial, pharmaceutical, and biomedical applications in which sterilization of TMCs might be a prerequisite. Active release is shown to be efficiently triggered by varying pH and/or salinity, with different profiles for TMCs from sulfited and nonsulfited species. Surfactants also affect the stability of TMCs significantly, with effects eventually amplifiable by pH and the inherent kosmotropic and chaotropic characteristics of salt components in solutions.