Development of amphoteric alginate/aminated chitosan coated microbeads for oral protein delivery

A new amphoteric biopolymer carrier based on alginate and aminated chitosan coated microbeads (Alg/AmCS) was developed and characterized for bovine serum albumin (BSA) protein delivery. The amphoteric character was investigated through studying the swelling and in vitro BSA release behaviors of the developed microbeads in simulated gastric (SGF; pH1.2), intestinal (SIF; pH6.8), and colonic (SCF; pH7.4) fluids. The pH sensitivity was found to depend on the amount of AmCS in the coating medium. The results were interpreted from the view of the individual pH sensitivity of alginate and aminated chitosan in addition to the ionic interaction between them under the studied pHs. Besides; it was found that the BSA loading efficiency (LE) exceeded 82% regardless of the initial concentration of BSA. The released amount of BSA reached approximately 63% and 86% in SIF and SCF, respectively, using 0.25% AmCS. The stability of alginate microbeads in SCF was improved with increasing AmCS concentration in the coating medium up to 2%. Furthermore, the developed microbeads demonstrated their ability for biodegradation in addition to their antibacterial activities against selected bacterial strains. The results clearly suggested that Alg/AmCS coated microbeads could be suitable carriers for site-specific protein delivery in the intestinal and colon tracts.