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Photoresponsive mesoporous silica nanocarriers for paraquat with substantially reduced acute toxicity and effective
Chaonan Li1, Yiping Liu1, Yalan Mo2
1College of Chemistry and Chemical Engineering, Central South University, Changsha, China.
Background:
Paraquat (PQ) is a fast-acting non-selective herbicide, but its high mammalian toxicity and environmental risks severely limit its safe use. In this study, a photoresponsive controlled release formulation (PQ@MSN@SP) was constructed by loading paraquat into amine-functionalized mesoporous silica nanoparticles (MSN-NH₂) and using spiropyran derivatives (SP-COOH) as photoresponsive gatekeepers.
Results:
PQ@MSN@SP nanoparticles exhibited a hexagonal prismatic morphology with an average particle size of 475.2 nm and a PQ loading capacity of 13.63%. Under UV irradiation or natural sunlight, the spiropyran moieties underwent reversible photoisomerization, which triggered PQ release. In vitro release studies demonstrated distinct photoresponsive sustained-release behavior. Stability tests further showed enhanced paraquat stability under alkaline conditions. Herbicidal assays indicated that PQ@MSN@SP maintained herbicidal efficacy comparable to that of technical-grade paraquat under sunlight exposure. Moreover, cell viability assays and acute toxicity studies in mice indicated that PQ delivery via the PQ@MSN@SP system markedly reduced cytotoxicity and acute toxicity compared with technical-grade paraquat.
Conclusion:
PQ@MSN@SP represents a safer paraquat delivery system that combines effective weed control with substantially reduced toxicity. This formulation offers a practical approach to the risk-mitigated use of highly hazardous herbicides in agricultural weed management. © 2026 Society of Chemical Industry.
