Intestine-targeted delivery potency of the O-carboxymethyl chitosan-gum Arabic coacervate: Effects of coacervation acidity and possible mechanism

•Crosslinked O-CMC-GA coacervates swell more severely in the gastric fluid.•Higher coacervation acidity leads to greater swelling degree but less BSA release.•Coacervation acidity affects the matrix density and composition of coacervates.•O-CMC-GA coacervates can deliver hydrophobic compounds to the intestine.•The delivery potency of O-CMC coacervates varies with coacervation acidity.

The potential of the glutaraldehyde-crosslinked O-carboxymethyl chitosan (O-CMC)-gum Arabic (GA) coacervate as an intestine-targeted delivery system for hydrophobic compounds was concerned. OCMC-GA coacervates and emulsified bovine serum albumin (BSA)-loaded microcapsules were prepared in pH 3.0, 4.5, and 6.0 and their swelling behaviors as well as BSA release profiles in simulated gastrointestinal fluids were measured. All the coacervates showed higher swelling ratios in the simulated gastric solution than in the simulated intestine and colon solutions and the values increased as the coacervation pH increased from 3.0 to 6.0, but a reversed trend was observed for the BSA release profile. SEM, TEM, and CLSM analysis revealed that the coacervation acidity influenced the swelling and BSA release behavior by changing the matrix density and O-CMC content of the coacervates. It was concluded that the O-CMC-GA coacervate could be used to deliver hydrophobic compounds to the intestine and its delivery performance could be tailored by selecting appropriate coacervation acidity and crosslinking degree.