Preparation of alginate hydrogels through solution extrusion and the release behavior of different drugs

Homogeneous alginate hydrogels were facilely fabricated through solution extrusion process. CaCO₃ and D-glucono-δ-lactone (GDL) were used as the gelation agents. The slow gelation of alginate was realized by the in-situ release of Ca²⁺ from CaCO₃ particles induced by hydrolysis of GDL to reduce pH. Slight gelation during the extrusion caused the enhanced strength of the alginate solutions, leading to the extrudability of the blends. This method enables to produce alginate hydrogels in a single step via extrusion, which is economically advantageous to conventional lab-scale preparation for mass production. Three different drugs, ibuprofen, acetaminophen, and methylthionine chloride, were used as model drugs to evaluate the drug release behavior of the alginate hydrogels. It was demonstrated that the drug release behavior was significantly adjusted by both the drug solubility and the ionic interaction between alginate and the drug molecule. It was shown that solution extrusion process is a feasible method to produce alginate-based drug delivery systems.