Design and evaluation of curcumin-loaded sodium alginate/lignosulfonate beads for controlled pesticide release in sustainable agricultural applications

Abstract

Biopesticides often face limitations in agriculture due to poor solubility, photodegradation, and environmental loss. This study developed calcium-crosslinked sodium alginate–lignosulfonate beads for sustained curcumin delivery and evaluated the effect of crosslinking duration. SEM showed that increasing crosslinking time produced denser bead structures, reducing diffusion and release. FTIR confirmed hydrogen bonding, XRD indicated loss of curcumin crystallinity, and DSC–TGA demonstrated modified thermal stability. Entrapment efficiency reached 100% with a loading capacity of 33.33%. 1-min crosslinked beads showed best performance, releasing about 75–77% curcumin over 31 days, whereas longer crosslinking limited release. Photostability improved significantly, reducing the degradation rate and extending curcumin half-life. The encapsulated formulation exhibited improved soil retention and reduced leaching compared with free curcumin. Molecular docking showed favourable binding of curcumin to acetylcholinesterase, and in vitro assays confirmed enhanced inhibitory activity of the bead formulations. These biodegradable beads show promise as eco-friendly controlled-release pesticide carriers.