Fabrication of Janus silica nanocarriers for enhancing foliage retention

The deposition performance of drug droplets on plant foliage has played a key role in determining pesticide availability. Herein, we designed and prepared hollow mesoporous silica (HMS) carriers using the etching method. The HMS carriers are uniform hollow spheres with a diameter of 400 nm and shell thickness of 50 nm. The as-prepared HMS carriers show high specific surface area (1148.9 m2/g) and pore volume (0.89 cm3/g) and are suitable for loading pesticides. The HMS carriers were further modified with amino and alkyl groups to form Janus structure (J-HMS) carriers with the amphipathic surface. Abamectin (Aba) is used as a model pesticide to assess the release and adhesive property of J-HMS carriers. The Aba-J-HMS system displayed pH-responsive release behavior and improved wetting and adhesive performance on both hydrophilic and hydrophobic foliar surfaces. In addition, the J-HMS had a good ultraviolet (UV) shielding performance.