Temperature and ROS Dual-Responsive Hydrogels as Controlled-Release Carriers for Fungicide Delivery and Improving Antifungal Efficiency

The direct application of pesticides results in a low utilization efficiency and can cause environmental pollution. Stimulus-responsive carriers have attracted considerable attention due to their ability to control pesticide release. However, the application of conventional mesoporous silica nanoparticles (MSNs) is limited because of their low drug-loading capacity and their tendency to pesticide leakage when used as drug delivery systems. In this study, the temperature and ROS dual-responsive hydrogel (N-MSN–TK–SA) were successfully prepared by synergistically introducing thioketone (TK) covalent bonding with amino-modified mesoporous silica nanoparticles (N-MSNs) via amide bond followed by combination with sodium alginate (SA) by ionic cross-linking. Structural characterization revealed that the N-MSN possessed uniform mesopores (3.8148 nm), while the hydrogel exhibited larger mesopores (6.7547 nm), contributing to both efficient drug encapsulation and loading. The controlled-release behavior of N-MSN–TK–SA was explored with carbendazim as the antifungal agent. The results showed that the N-MSN–TK–SA-loaded carbendazim demonstrated a temperature and ROS response and had better antifungal activity than the commercial carbendazim. The maximum cumulative release rate of N-MSN–TK–SA-loaded carbendazim reached 90.5% at 46 h in the 40 μM H 2 O 2 and 95% at 35 °C. The release of carbendazim in the N-MSN–TK–SA is most consistent with the first-order kinetic model. Moreover, N-MSN–TK–SA-loaded carbendazim had excellent storage and thermal stability. At equivalent drug loading, the carbendazim-loaded hydrogel achieved an 85.48% inhibition rate, significantly outperforming commercial carbendazim powder (48.48%). Furthermore, the hydrogel carrier can reduce the toxicity of carbendazim to aquatic organisms and is environmentally friendly, which suggests that it has promising practical applications. The controlled-release strategy developed in this study can improve antifungal utilization and promote green agriculture.