Calcium-binding casein phosphopeptides-loaded chitosan oligosaccharides core-shell microparticles for controlled...

Core-shell microparticles based on food-grade biopolymers are of particular interest for biological components delivery owing to their unique controlled release property. Here, we introduce a method to fabricate calcium-binding casein phosphopeptides (CPP)-loaded core-shell microparticles for oral calcium delivery, based on ionic gelation interactions between chitosan oligosaccharides (COS) and tripolyphosphate (TPP). The fabrication method, textural properties, calcium binding capacity, pH-dependent stability, thermal properties, intermolecular forces, morphology characterizations, the controlled calcium release and calcium absorption properties in vitro and vivo of core-shell microparticles were studied. The results showed that COS was successfully crosslinked through TPP while CPP-Ca was incorporated in it, and microparticles showed appropriate textural properties, calcium-loaded capacity, and thermal properties. Morphology observations showed the core structures were successfully coated with outer-layer COS shell. Additionally, the calcium release and absorption studies in vitro and in vivo exhibited CPP-Ca-loaded microparticles could achieve controlled calcium release and sustained calcium uptake. Therefore, the fabricated CPP-Ca-loaded core-shell microparticles could function as promising calcium supplements for enhancing calcium bioavailability.