Development of a pH/Cellulase Dual-Responsive Fe-MOFs Delivery System for Targeted Control of Maize Fungal Diseases

The iron-based metal–organic frameworks (Fe-MOFs) NH2-MIL-101(Fe) (MIL) has gained widespread attention as a drug carrier material in agriculture. In this study, a multifunctional nanocomposite, MIL@A@D@C, was successfully synthesized by loading the fungicide azoxystrobin (AZOX) and immunoinducer d-cellobiose (D) onto MIL, followed by surface modification with carboxymethyl cellulose (CMC). The loading capacity of MIL was optimized by varying solvent conditions and the mass ratio of MIL to AZOX, revealing that ethanol as the reaction solvent and a MIL: AZOX mass ratio of 1:4 resulted in the highest loading efficiency (6.73%). MIL@A@D@C exhibited pH- and cellulase-responsive controlled release behavior. In vitro antifungal assays demonstrated that MIL@A@D@C at a low concentration of 1 ppm effectively inhibited Colletotrichum graminicola (the causal agent of maize anthracnose). Foliar application experiments further confirmed that the composite formulation achieved significant inhibition at a low dosage of 10 ppm, outperforming commercial azoxystrobin products. Plant and animal safety assessments indicated that MIL@A@D@C possessed enhanced biosafety. These findings highlight the potential of MIL@A@D@C as an environmentally friendly and highly effective nanodelivery system for crop disease management.