Preparation Of Hollow Silica Carriers And Their Applications For Sustained Pesticide Release Formulations

In this work, two different pesticides of dicamba and prochloraz were loaded into self-prepared porous hollow silica nanoparticles (PHSN), respectively, by a supercritical fluids drug loading (SFDL) method. Both of the drug loading amounts were above50wt%. The release results of formulation of dicamba and prochloraz showed that the drug release rate is fast at the beginning to achieve the immediate curing effects, and then the rate slow down to sustain the prolonged treatment. By choosing proper dispersants and wetting agents, the two pesticide-loaded PHSN were further prepared as wettable powders (WP) formulation for sustained release. Both of dicamba WP (wetting time:72s;1h standard suspended rate:87.5%;6h suspended rate:87.03%; particles size:below5μm) and prochloraz WP (wetting time:28s;1h standard suspended rate:92.36%;6h suspended rate:90.56%; particles size:below10μm) are able to meet the requirements of WP by national standards and demonstrated some sustained release behaviors. By in situ hydrolysis of tetraethyl orthosilicate (TEOS) in water-oil (W/O) emulsions, validamycin-loaded silica hollow microspheres were prepared successfully. The drug-loaded microspheres had an amorphous hollow spherical structure with a diameter of7.5～15μm. Validamycin was encapsulated directly into the inner hollow spaces of the hollow silica particles by physical adsorption.The drug loading amount was about31.9wt%and over90%of the loaded drug was delivered smoothly in a sustained pattern.