Controlling the Release Profile Through Phase Control of Calcium Phosphate-Alginate Core-shell Nanoparticles in Gene Delivery

In this study, we aimed to control the drug release rate from calcium phosphate-alginate (CaP-Alg) core-shell nanoparticle (NPs) using CaP phases (brushite (DCPD) [Bru] and hydroxyapatite [HA]) generated under different pH conditions. Core-shell NPs consisted of an inorganic CaP core and an organic Alg shell and were synthesized by the water-in-oil emulsification and precipitation method. CaP-Alg NPs were synthesized under different pH conditions, resulting in the mineralization of CaP with Bru and HA in the core region of core-shell NPs. Albumin-fluorescein isothiocyanate conjugate (FITC-BSA) was used as a model drug for in-vitro drug release studies. CaP-Alg (Bru-Alg and HA-Alg) NPs exhibited a higher loading capacity and encapsulation efficiency than Ca-Alg NPs. The release behavior of synthesized core-shell NPs showed different patterns due to the pH-sensitivity of Alg and CaP. At physiological pH, Ca-Alg NPs exhibited an initial burst release behavior, while CaP-Alg showed controlled release behavior. Our results demonstrate that HA-Alg NPs are more suitable for controlled intracellular delivery while Bru-Alg NPs are more suitable for extracellular compartment delivery. Therefore, CaP-Alg NPs could be potential candidates for controlled gene and biomolecule delivery into cells for therapeutic purposes.