Structure, stability, and mechanism of dextran-CPP-Ca2+ conjugates: A novel high-efficiency calcium ion delivery system

Abstract

Calcium has limited bioavailability because of the formation of calcium phosphate deposits in the gastrointestinal tract. In this study, we prepared a dextran-casein phosphopeptide (CPP)-Ca²⁺ delivery system and evaluated for Ca²⁺ binding mechanism, structure, stability, and sustained release of Ca²⁺ and assessed inhibition of calcium phosphate precipitation. The results revealed that Ca²⁺ binds to dextran-CPP through the phosphate, carboxyl, and amino groups and forms crystal clusters. Furthermore, compared with single polymer CPP-Ca²⁺ conjugates, copolymer dextran-CPP-Ca²⁺ conjugates exhibited improved stability at various conditions (pH, temperature, and coexisting food), efficiently reduced the calcium phosphate precipitation, and improved sustained-release of Ca²⁺. Collectively, dextran-CPP-Ca²⁺ conjugates can be an efficient Ca²⁺ delivery system.

Keywords: Calcium bioavailability; Calcium delivery system; Calcium sustained-release; Copolymer conjugates.