Size control of chitosan capsules containing insulin for oral drug delivery via a combined process of ionic gelation with electrohydrodynamic atomization

Recently, the development of new insulin delivery strategies, such as oral drug delivery, has sparked the interest of many researchers. In this paper, microsized chitosan capsules containing insulin were produced via a combined process of ionic gelation with electrohydrodynamic atomization (EHDA). Produced airborne chitosan-insulin droplets were reacted with phytic acid to induce the binding between chitosan and phytic acid, resulting in chitosan capsules containing insulin. As the nozzle size decreased, the size and uniformity of the primary airborne droplets decreased and enhanced, respectively. The size of primary airborne droplets affected the uniformity of the chitosan capsules in size. Using a nozzle of 320 μm in diameter, the mean diameter of the capsules was 232 μm, which is much smaller than that of capsules formed using only the ionic gelation method. The insulin encapsulation efficiency was nearly independent of nozzle size and was above 92%. Through in vitro tests, when a nozzle smaller than or equal to about 700 μm was used, the sustained insulin release occurred in the artificial intestinal juice although the smaller capsules exhibited lower resistance to acidic conditions.