Characterization of concanavalin A-conjugated resistant starch acetate bioadhesive film for oral colon-targeting microcapsule delivery system

• Con A was conjugated to the resistant starch acetate molecules with 8–32 μg/mg.
• G′ and Tg changes of Con A-RSA film under simulated GIT conditions were analyzed.
• Colon-targeting controlled release can be achieved by adjusting the coupled Con A.
• Con A-RSA film coated microcapsules showed good colon-targeting and bioadhesion.
• Con A-RSA film is a potential colon-targeting bioadhesive film coating material.

For the effectiveness of bioactive ingredient targeting delivery in the gastrointestinal tract (GIT), the concanavalin A (Con A)-conjugated RSA film was developed for the potential bioadhesive coating material for colon-targeting bioadhesive microcapsules which were designed by the method of extrusion–spheronization and film coating process. The Con A-conjugated RSA films with coupled Con A from 8 to 32 μg/mg showed sufficient higher storage modulus (G′) and glass transition temperature (Tg). The G′ and Tg increased as immersion in simulated digestive fluids progressed which allowed the films transformed from a viscoelastic state to a glassy state and is benefit for the bioactive ingredients releasing. Through adjusting the amount of coupled Con A the brittleness time and brittlement of Con A-conjugated RSA film could be adjusted and controlled for matching the colon targeting and releasing performance. The in-vitro and in-vivo study demonstrated that the Con A-conjugated RSA film coated microcapsules have good colon targeting and bioadhensive properties which could not only target bioactive molecules to the colon but also increase the residence time of the microcapsules for 72 h in the colon.