Mesoporous Silica Nanoparticles Carrier for Urea: Potential Applications in Agrochemical Delivery Systems

Nanotechnology-based agrochemical delivery systems would ensure efficient and economical utilization of these very important agricultural inputs. In this study, mesoporous silica nanoparticles with particle diameters of similar to 150 nm and pore sizes of similar to 2.5 nm were synthesized via liquid crystal templating mechanism. Urea, as a model agrochemical molecule, was entrapped in the mesopores of the siliceous material by simple immersion loading using aqueous urea solutions. About 15.5% (w/w) of urea was loaded inside the pores mainly by physisorption while the total adsorption capacity of mesoporous silica nanoparticles could reach up to 80% (w/w). Highly concentrated urea solution was found to be more effective due to high driving concentration gradient generated. Release process of the urea-loaded mesoporous silica nanoparticles in water and soil indicated a two stage sustained slow release-profile. The findings for soil release studies revealed at least fivefold improvement in the release period. By the ability to entrap urea guest molecules into its mesopores and release them in a controlled manner, mesoporous silica nanoparticles demonstrated its great potential as a nanocarrier for agrochemicals.