Linear Supramolecular Block Copolymer Micelles for ROS-Responsive Release of Antimicrobial Pesticides

After cotton is invaded by cotton aphids and other pests, the function of its defense system decreases, and it is more vulnerable to infection by bacteria. When plants are invaded by external bacteria, they quickly produce reactive oxygen species (ROS). In this paper, ROS-responsive pesticide release carrier materials are designed and prepared for solving bacterial infections in plants by ring-opening polymerization of ε-caprolactone (ε-CL) and β-cyclodextrin (β-CD) to obtain a hydrophobic guest (β-CD-PCL). Thioketal (TK) was modified by adamantane (Ad) and poly(ethylene glycol) monomethyl ether (mPEG5000-OH) to form a hydrophilic guest (mPEG5000-TK-Ad). β-CD-PCL and mPEG5000-TK-Ad interact with each other to form an amphiphilic polymer (mPEG5000-TK-Ad@β-CD-PCL), which is loaded with carbendazim (MBC) by self-assembly (MBC-mPEG5000-TK-Ad@β-CD-PCL). The polymer had ROS response characteristics, and the release rate of C increased from 30 to 57% after 120 h of ROS stimulation. The inhibition rate of Rhizoctonia S. was 92.23% when the effective concentration of MBC was 30 mg/L. The critical micelle concentration (CMC) of the polymer is 8.30 mg/L, and the micelle had storage stability for at least 14 days, showing good storage stability. Therefore, this ROS-responsive polymer carrier has great potential as a carrier for antimicrobial pesticides.