Encapsulation of biocontrol agents in alginate hydrogels: A strategy for enhanced stability and release

Biocontrol relies on bio-molecules and micro-organisms to protect crops against pests and diseases. However, the instability of these agents in natural conditions (UV exposure, temperature, humidity, soil pH…) remains a major limitation to its widespread application. This study investigates the use of alginate hydrogels as protective matrices for biocontrol agents. The encapsulation properties of alginates are examined, with a focus on their ability to entrap various compounds and regulate their release. We show that the choice of gelling cations strongly affects hydrogel properties: replacing Ca²⁺ with Cu²⁺ densifies the network, producing smaller pores and stiffer gels and can modulate the release of relatively large compound such as gold nanoparticles. The encapsulation of hydrophobic compound, often difficult in hydrogels, is studied and several enhancing strategies are proposed. Furthermore, this work shows that alginate hydrogels can successfully encapsulate macro-organisms These findings highlight alginate hydrogels as versatile carriers with strong potential to advance sustainable biocontrol application.