Effect of cross-linking agents on sodium alginate-based quercetin beads: physicochemical properties and controlled release kinetics

Alginates have a variety of biological, physical, and chemical properties that can be modified to meet a specific purpose. Ionic crosslinking is an easy method of alginate modification. This study examined the ionic crosslinking agents (Ca2+, Ba2+, Mg2+) on swelling ratio, water solubility, and % sol-gel fraction of modified alginate. The performance of the modified alginate used to encapsulate quercetin, such as % encapsulation efficiency (% EE), % release of quercetin, and quercetin release kinetics were examined. The variables used in this study were the concentration of alginate and ionic crosslinking agents. At 3% alginate concentration and 0.3 M, ionic crosslinking agent concentration positively correlated with swelling ratio and water solubility. In contrast, the ionic crosslinking agent that positively correlates to the % sol-gel fraction is Ca2+. Encapsulation of quercetin using a crosslinking agent with ion Ca2+ and 2.5 ppm of quercetin concentration showed the highest % EE of 87%. Modified alginate induced quercetin release from beads at pH 1.4 and 7. The release of quercetin from modified alginate followed the Korsmeyer-Peppas kinetic model (R2 >0.99). The results of the FTIR analysis confirmed that a new peak at 1271 cm-1 was C-O-C characteristic of quercetin, indicating quercetin loaded on encapsulated beads. The morphological analysis showed that the surface of modified alginate (Ca-Ag/Ba-Ag/Mg-Ag) was rough and porous. This study established that modified alginate using different ionic crosslinking agents can be a suitable matrix for encapsulating quercetin.