Efficient nanostructured platforms for Thiram formulation

Abstract

Peanut smut, caused by Thecaphora frezii, leads to severe annual yield losses worldwide, particularly in Córdoba, Argentina. The fungicide Thiram (tetramethylthiuram disulfide) is widely used to control this disease, but its low aqueous solubility (∼30 mg L⁻¹) is a major limitation to its application. Nanocarriers could enhance Thiram's solubility and stability, possibly increasing its efficiency in agricultural applications. To test this in our laboratory, Thiram was encapsulated in two different delivery systems: a) zirconium-based MOF-808 nanocrystals (nMOF-808) and b) Tween 80/Span 80 (1 : 1) niosomes. nMOF-808 was able to incorporate up to 2 g of the fungicide per gram of absorbent and keep it colloidally stable in aqueous suspension for one day. On the other hand, in the presence of niosomes, it was possible to dissolve up to 0.1 mM Thiram in a colloidally stable form for approximately one month under appropriate conditions. Both systems proved to be photoprotective for the fungicide and were capable of controlled release of the encapsulated Thiram. The incorporation of Thiram into nMOF-808 could be interpreted according to the Langmuir model and kinetically by the intraparticle diffusion model, which is uncommon in the literature for the adsorption of neutral molecules in MOFs. These laboratory results indicate that the studied nanoplatforms are promising for future field studies aimed at optimizing efficiency and sustainability in the control of peanut smut and other fungal diseases.