Delivery of Hexaconazole by the Carboxymethylcellulose grafting and Cellulase/pH responsiveness hollow mesoporous silica nanoparticles.

Conventional pesticides are easily lost, and poorly targeted deposition causes pollution and economic losses because of their large particle sizes. Cellulase/pH Responsiveness Hollow Mesoporous Silica Nanoparticles (Hex/HMSN-CMC) was developed to respond rapidly to changes in the environment. The particle size of Hex/HMSN-CMC was 133.44 nm. The characterization results confirmed the introduction of CMC and a Hex loading capacity of 12 %. Controlled-release kinetics indicated that the drug-loaded system could exhibit specific responses to pH and cellulase, with the cumulative release rate exceeding 80 %. Bioactivity assays showed that the EC₅₀ values of Hex/HMSN nanoparticles and the commercial hexaconazole suspension against Rhizoctonia solani were 0.638 mg/L and 1.281 mg/L at 5 days, and 1.404 mg/L and 2.454 mg/L at 10 days after application, respectively. Furthermore, Hex/HMSN-CMC demonstrated the ability to transport within mycelium and rice plants. Contact angle experiments showed that the wetting ability increased with the introduction of CMC. Additionally, Hex/HMSN-CMC increased rice seed germination than Hex alone. Zebrafish toxicity assays indicated the LC₅₀ value of Hex/HMSN-CMC to zebrafish was increased by 16.65 % compared with Hex SC. These results indicate hexaconazole delivery system with dual responsiveness to pH and cellulase could achieve targeted transportation and reduce pesticide runoff.