Fungicide itself as a trigger to facilely construct Hymexazol-Encapsulated polysaccharide supramolecular hydrogels with controllable rheological properties and reduced environmental risks

Abstract

Hydrogels with porous networks have received considerable attention in cargo delivery systems due to the inherent versatile performances. However, ideal strategy that bioactive molecule itself spontaneously triggers natural polymers to form self-delivery hydrogels has been less exploited. Herein, the addition of hymexazol into the mixed aqueous solution of alginate and carboxymethyl chitosan can spontaneously trigger the formation of fungicide-encapsulated polysaccharide supramolecular hydrogels with controllable rheological properties and tunable multifunctionality. The hydrogels are three-dimensional porous network structures possessing shear-thinning, self-healing, and pH and ionic strength-responsive swelling properties. Furthermore, soils amended with hydrogel demonstrated enhanced water-holding and water-retention capacities. The hydrogels can not only decrease the leaching of hymexazol in soil, but also increase its retention capacity on hydrophobic interface, and significantly inhibit the fragmentation and rebound of the droplets on hydrophobic surface. More importantly, in addition to the good fungicidal activity, hydrogels can promote the sprouting of wheat seeds compared to the free hymexazol aqueous solution, demonstrating obvious biosafety to target plant through the gelation of active ingredient. This intriguing bioactive molecule itself-triggered self-delivery approach can bestow the active ingredient tunable multifunctionality without sacrificing the bioactivity, offering a promising and practical strategy for various application scenarios in sustainable agricultural practices.