Layers of Electrostatically Self-assembled Composite Hydrogel Beads Based on Porous Starch and ZnO Filling for Intestinal Sustained Release of Quercetin

Quercetin (Que) is a naturally occurring bioactive compound with various potential health benefits, but its low stability and low bioaccessibility limit its application in functional foods. Therefore, there is an urgent need to prepare a novel composite hydrogel bead with efficient and controlled release. Specifically, porous starch (PS) was first prepared by enzymatic hydrolysis to increase the specific surface area and thus enhance the adsorption rate of Que. Scanning electron microscopy confirmed the formation of the PS and the adsorption of Que. The maximum swelling properties of carboxymethylcellulose-porous starch composite hydrogel beads (CQPZ) were reduced by adding different amounts of zinc oxide to achieve slow release. The results showed that the higher the amount of zinc oxide, the stronger the slow-release performance, while the lower the drug loading capacity. To obtain composite hydrogel beads with both low swelling and high drug-carrying properties, bilayer gel beads (CQPZ/CS) were prepared by electrostatic self-assembly of carboxymethyl cellulose and chitosan. The experimental results showed that the drug loading was significantly increased by nearly 2-fold while enhancing the slow-release performance. In addition, the CQPZ/CS composite hydrogel beads enhanced the stability of Que under light and heat conditions, and the DPPH radical scavenging rate after UV irradiation was still greater than 75%, which was much higher than that of free quercetin (31.08%). In conclusion, the prepared hydrogel beads are a promising delivery system for bioactive compounds.