Fabrication of copper nanoparticle composite nanogel for high-efficiency management of Pseudomonas syringae pv. tabaci on tobacco.

Background: Copper nanoparticles (CuNPs) can release copper ions (Cu ) to control bacterial diseases on crops. However, the high concentration of the CuNPs applied in disease controlling can highly limit their application. In this work, by in situ reducing CuNPs in alginate nanogels and coated with cetyl trimethyl ammonium chloride (CTAC), a CuNP composite nanogel was fabricated as a new nanopesticide with low copper content.

Results: Data showed that the CTAC coating would affect the antibacterial activity and leaf surface adhesion of the nanogel, while CuNP content could also influence the membrane damage ability of the gel. The nanogel could depress the growth of bacteria by rupturing its membrane and show a minimum inhibitory concentration (MIC) as low as 500 μg mL , which only contain 58 μg mL CuNP, and achieve a 64% of therapeutic efficiency (with 1000 μg mL nanogel) in in vivo experiments, higher than that of commercial bactericide thiodiazole copper. Furthermore, the application of the nanogel can also perform a growth-promoting effect on the plant, which may be due to the supplement of copper element provided by CuNP.

Conclusion: The CuNP composite nanogel fabricated in this work performed high leaf disease controllability and safety compared to the commercial bactericide thiodiazole copper. We hope this nanogel can provide a potential high-efficiency nano-bactericide that can be used in the leaf bacterial disease control.