Self-Assembled Sphere Covalent Organic Framework with Enhanced Herbicidal Activity by Loading Cyhalofop-butyl

Area of Science:

• Agricultural Science
• Materials Science
• Nanotechnology

Background:

• Nanopesticides offer efficient pest control in modern agriculture.
• Covalent organic frameworks (COFs) are promising carriers for nanopesticides due to their properties.
• Current methods limit COF-based nanopesticides to charged molecules, hindering the use of uncharged pesticides.

Purpose of the Study:

• To develop a mild and effective strategy for loading uncharged pesticide molecules into COFs.
• To explore the use of host-guest interactions for pesticide loading.
• To evaluate the efficacy of the developed nanopesticide delivery system.

Main Methods:

• A neutral herbicide, cyhalofop-butyl (CB), was loaded into sphere COF (SCOF) using a host-guest strategy.
• The loading capacity of CB into SCOF (CB@SCOF) was determined.
• The herbicidal activity of CB@SCOF was compared to commercial CB emulsifiable (EC) against target weeds.

Main Results:

• A high loading capacity of 57% (w/w) CB into SCOF was achieved without ionic interaction.
• Smaller CB@SCOF particles (150-200 nm) demonstrated enhanced penetration into weed tissues.
• CB@SCOF improved CB's water solubility and photostability, leading to superior herbicidal activity against *Echinochloa crus-galli* and *Leptochloa chinensis*.

Conclusions:

• A mild and high-efficacy strategy for loading uncharged pesticides into COFs was established.
• The developed COF nanosphere delivery system shows significant potential for weed control in sustainable agriculture.
• This research expands the application of COFs in developing advanced nanopesticide formulations.