Synthesis, physiochemical properties, colloidal stability evaluation and potential of ionic liquid modified CS-TPP MPs in controlling the release rate of insulin

Abstract

In the present research, four different ionic liquids (ILs) including 1-Butyl-3-methylimidazolium hydrogen sulfate [BMIM][HSO4], 1-Butyl-3-methylimidazolium acetate [BMIM][OAc], 1-Butyl-3-methylimidazolium chloride [BMIM][Cl], Choline chloride (ChCl) and a surfactant Cetyltrimethylammonium bromide (CTAB) were used in the formulation for preparation of Chitosan-Tripolyphosphate microparticles (CS-TPP MPs) through the ionic gelation method (IGM). The colloidal stability of these MPs was evaluated in HCl medium and the most suitable formulation based on ChCl used for encapsulation of Insulin. All the synthesized MPs are well characterized for size, PDI, zeta potential, structural changes, thermal stability, endo/exothermic behaviour, images, and elemental analysis. The Insulin release experiments were conducted in HCl and PBS mediums, where the MPs containing 0.10–0.40% w/v and 0.10% w/v ChCl evaluated, respectively. In this regard, the formulation containing the 0.10% w/v ChCl protected most of the Insulin successfully (no burst release) in the HCl medium, while a triggered and sustained release occurred in the PBS medium. The kinetic study revealed that the MPs containing the 0.10–0.30% w/v ChCl has a good potential in controlling the release rate of Insulin and the mechanism mainly followed the erosion/relaxation of the polymer matrix with a limited diffusion process.