Microparticles based on carboxymethyl starch/chitosan polyelectrolyte complex as vehicles for drug delivery systems

Microparticles with oval-shape morphology and rough and porous surfaces were prepared by polyelectrolyte complexation of carboxymethyl starch (CMS) and chitosan (Cs). CMS with DS of 0.5, the polyanionic moiety, was synthesized from rice starch with low content of amylose (6%). A preliminary investigation revealed that this kind of starch is more susceptive to esterification than rice starches with higher contents of amylose. The CMS/Cs microparticles showed higher chemical and thermal stability than microparticles prepared by conventional ionotropic crosslinking of Cs with TPP ions. The carboxymethyl groups of CMS are more efficient to neutralize the positive groups of Cs and, also, enhance the entrapment of bovine serum albumin (BSA) in the CMS/Cs matrix as compared to Cs/TPP. In vitro experiments conducted in simulated gastric fluid (pH 1.2) and simulated intestinal fluid (pH 6.8) with the testing microparticles revealed that the CMS/Cs-BSA microparticles exhibit a highlighted pH-dependent release profile. This desirable property allows controlling the release of BSA more efficiently, which minimizes undesirable issues (e.g. burst effect and non-sustained release). Furthermore, the BSA release from CMS/Cs-BSA microparticles in SIF follows an ideal Zero-order kinetics, which is very attractive for a drug delivery system. Therefore, microparticles based on CMS/Cs polyelectrolyte complex may be promising to control the drug release in specific regions of the gastrointestinal tract. (C) 2018 Production and hosting by Elsevier B.V. on behalf of King Saud University.