Sugar-sensitive polyelectrolyte microcapsules containing insulin

Sugar-sensitive microcapsules containing insulin were prepared by a layer-by-layer (LbL) deposition of alginic acid (AGA) and phenylboronic acid-modified poly (allylamine) (PBA-PAH) on the surface of a calcium carbonate (CaCO₃) microparticle in which insulin had been embedded, followed by dissolution of the CaCO₃ core. The microcapsules thus prepared were stable at pH 7.0-9.0. In the presence of 10-100 mM fructose or glucose, the release of insulin was significantly enhanced depending on solution pH and sugar concentration. The sugar-triggered release of insulin was explained on the basis of decomposition of the microcapsules, which in turn was caused by competitive binding of added sugar to the phenylboronic acid moieties in the LbL film.