Increased Stability of Polysaccharide/Silica Hybrid Sub‐Millicarriers for Retarded Release of Hydrophilic Substances

Abstract

AbstractThis work reports an in situ strategy for the synthesis of hybrid sub‐millispheres as carriers for encapsulating and controlling the release of hydrophilic pharmaceutical compounds in both neutral and acidic media. An organic–inorganic hydrogel is prepared by ionotropic gelation, and its efficiency for entrapping hydrophilic molecules is investigated. Two biopolymers, namely chitosan or alginate, are used to generate a scaffold network, in which the formation of silica nanoparticles takes place in situ by a sol–gel process. Model hydrophilic molecules (erioglaucine disodium salt and ephedrine hydrochloride) are encapsulated within polymer matrix, and the subsequent release is controlled by tailoring the hybrid network structure. Kinetic studies demonstrate that the release of the active substance is slower in the presence of silica, which increases as well the structural stability of the carrier in both neutral and acidic media. As a result, by incorporating nanostructured silica into the polymer matrix, the presented system overcomes the limitations of the ionotropic method for entrapping hydrophilic substances.