Chitin nanocrystals supported copper: a new nanomaterial with high activity with P. syringae pv. Tabaci.

Background: The application of chemical pesticides in control of plant bacterial disease may cause potential environmental pollution. Herein, based on the resistance-inducing ability and the special rod-like structure with high aspect ratio of bio-derived chitin nanocrystals (ChNC), a new Cu composite rod-like nanoparticle was fabricated (ChNC@Cu). The antibacterial activity of the composite nanoparticle was systematically studied, and its safety was evaluated.

Results: TEM, FTIR, ICP and other characterization methods proved that ChNC@Cu is a nano rod-like structure, with a Cu loading capacity of 2.63%. In vitro experiments showed that the inhibition rate of ChNC@Cu to P. syringae pv. tabaci was more than 95% when the copper content was 41.6 μg mL . In vivo experiments showed that ChNC@Cu had a good protective effect on P. syringae pv. tabaci of tobacco. In addition, ChNC@Cu exhibited stronger antibacterial activity than Thiodiazole copper (TC) at the same copper content. The study on the antibacterial mechanism of ChNC@Cu proved that ChNC@Cu caused bacterial death by destroying the bacterial cell membrane structure and damaging the DNA bacteria. And ChNC@Cu is highly safe for plants and can promote seed germination and plant growth.

Conclusion: The special rod-like structure of ChNC can enrich Cu to form ChNC@Cu. ChNC@Cu has a good protective effect on bacterial infection of tobacco, and achieves a great antibacterial activity at low Cu concentration, which indicated that ChNC@Cu has induced resistance and antibacterial effect. As a novel green nanofungicide, ChNC@Cu has high potential application value in control of agricultural bacterial diseases. © 2023 Society of Chemical Industry.