Synthesis and antifungal activity of chitosan-silver nanocomposite synergize fungicide against Phytophthora capsici

Fungicides are important tools for preventing pathogens and maintaining crop quality; however, their effectiveness was directly affected by high-priced, toxicity, and environmental pollution. As a result, it is necessary to get a safe and efficient antimicrobial agent against agricultural pathogens. In this study, silver-incorporated chitosan nanocomposites (Ag@CS) were first prepared in which CS was used as reducing and stabilizing agent and then these nanocomposites was synergized with fungicide Antracol (An), Ag@CS/An, against Phytophthora capsici causing Phytophthora blight in pepper. The obtained nanocomposites were characterized by Fourier transform infrared (FTIR), X-ray diffraction analysis (XRD), thermogravimetric analysis (TGA), dynamic light scattering (DLS), and transmission electron microscopy (TEM). These results showed that Ag@CS and Ag@CS/An were successfully synthesized with spherical shape AgNPs having diameter of 20.3 +/- 0.7 nm and 44.6 +/- 0.3 nm, respectively. More importantly, Ag@CS/An was found to have significantly stronger antifungal ability than each component alone, analyzed by agar diffusion method. It might be anticipated that Ag@CS/An has a promising future as nano-antibiotic materials for agriculture.