Photo-Stimuli Smart Supramolecular Self-Assembly of Azobenzene/β-Cyclodextrin Inclusion Complex for Controlling Plant Bacterial Diseases

Controllable and on-demand delivery of supramolecular systems have received considerable attention in modern agricultural management, especially for managing intractable plant diseases. Here, an intelligent photoresponsive pesticide delivery system is reported based on beta-cyclodextrin (beta-CD) and azobenzene, which overcomes the resistance of phytopathogens caused by the irrational use of conventional pesticides. Antibacterial bioassays illustrated that designed azobenzene derivative 3a possesses the most efficient bioactivity with EC50 values of 0.52-25.31 mu g mL(-1) toward three typical phytopathogens. Moreover, the assembly of the supramolecular binary complex 3a@beta-CD is successfully elucidated and displays exceptional inhibitory activity on biofilm formation. Of note, this supramolecular binary complex significantly improves the water solubility, foliar surface wettability, and shows marked light-responsive properties. In vivo anti-Xoo assays reveal that 3a@beta-CD has excellent control efficiency (protective activity: 51.22%, curative activity: 48.37%) against rice bacterial blight pathogens, and their control efficiency can be elevated to values of 55.84% (protective activity) and 52.05% (curative activity) by UV-vis exposure. In addition, the 3a@beta-CD are non-toxic toward various non-target organisms. This study therefore offers new insights into the potential of host-guest complexes as a feasible pesticide discovery strategy characterized by a safe, biocompatible, light-responsive release, and antibiofilm properties for overcoming intractable plant bacterial diseases.

Automated summary

A photoresponsive pesticide delivery system based on beta-cyclodextrin and azobenzene is reported, which can overcome the resistance of plant pathogens caused by the irrational use of conventional pesticides. The system shows efficient bioactivity against typical phytopathogens and exceptional inhibitory activity on biofilm formation. It also exhibits improved water solubility, foliar surface wettability, and light-responsive properties.