Multifunctional Borax Cross-Linked Hydroxypropyl Guar Gum Hydrogels with Crop Nutritional Function as Carriers for Dual-Responsive Acaricide Release

Hydrogels with porous networks have received considerable attention in smart pesticide delivery due to their inherent versatility. In this study, acaricide cyetpyrafen (CPF)-loaded borax (BO) cross-linked hydroxypropyl guar gum (HPG) (CPF@BO-co-HPG, CBG) hydrogels were prepared by cross-linking and pesticide loading simultaneously. The flowable CBG hydrogels with 3D porous network structures had better wetting and spreading ability on Citrus reticulata Blanco leaves and a hydrophobic interface. The nonflowable CBG hydrogels had pH- and temperature-responsive release properties. Meanwhile, the acaricidal efficacy of CBG against Panonychus citri (McGregor) at both 24 and 48 h was significantly higher than those of CPF-loaded BO-free HPG hydrogels. Furthermore, CBG had a nutritional function for cotton growth and environmental safety for zebrafish. This research developed a BO cross-linked HPG hydrogel as a smart pesticide delivery vehicle and crop nutrient replenishment, which can be widely applied in sustainable agriculture.