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Hydrogel beads based on the carbohydrate biopolymers kappa-carrageenan and sodium alginate were newly prepared. Both classical and experimental design (Taguchi) methods were used to obtain the optimum conditions for the full-polysaccharide hydrogel preparation. The carrageenan-alginate (Caralgi) beads exhibited a surface morphology smoother than that of the one-polysaccharide network beads. Infrared spectroscopy and DSC/TGA thermal methods were used to study the chemical structure and thermal properties of the beads. The carrageenan parts appreciably enhanced thermostability of the networks. The fully carbohydrate-based hydrogel beads are expected to be biologically compatible and degradable. They are being considered as new carriers for drug loading and controlled delivery systems.

Interpenetrating polymer network (IPN) hydrogel beads of carrageenan-sodium alginate (Caralgi) were prepared under mild conditions. Betamethasone acetate, as a water-soluble drug model, was simultaneously loaded while the hydrogel network was being formed. The effect of pH and temperature of the preparative media on the drug loading efficiency was investigated. Maximum loading efficiency (71%) was achieved at pH 4.8 and 55°C. The chemical structure and morphology of the Caralgi IPN hydrogels with and without drug were studied using FTIR and SEM analyses. The system exhibited a loading efficiency that depended on the pH and temperature. The in vitro release behavior by Caralgi IPN samples, prepared under various conditions, was evaluated and compared with that of the non-IPN alginate-Ca2+ and carrageenan-K + hydrogels at pH 1.2 and 7.4.

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