Green synthesis and characterization of CuO nanoparticles derived from Pimenta dioica and evaluating its activity against Tobacco streak virus

The synthesis of nanoparticles using plants represents a green and sustainable method that uses natural and non-toxic resources for nanoparticle production. In this study, CuO nanoparticles were synthesized from allspice (Pimenta dioica ), which served as both the capping and reducing agent during synthesis. Synthesised nanoparticles were validated using UV-Vis spectroscopy, X-ray diffraction, FT-IR analysis and Transmission Electron Microscopy (TEM). The monoclinic phase of the synthesised particles was revealed through the X-ray diffraction pattern indicating its crystalline nature. The UV -visible spectrum showed a strong absorbance of UV rays at a wavelength of 294 nm, confirming the presence of CuO nanoparticles. FT-IR analysis identified different functional groups from the phytochemicals in the plant extract used for the green synthesis, with peaks at 424.34 cm-1, 478.35 cm-1, 555.50 cm-1 and 648.08 cm-1 corresponding to Cu-O bond vibrations, thereby confirming the existence of CuO nanoparticles. TEM analysis revealed that the nanoparticles had spherical and hexagonal shapes, with sizes ranging from 10 to 20 nm. The antiviral potential of these nanoparticles was assessed against Tobacco streak virus, isolated from black gram plants, as spray applications at concentrations of 100, 200, 400 and 500 ppm. The preinoculation spray at 500 ppm of CuO nanoparticles, followed by challenge inoculation with the virus, yielded the most effective result, with a reduction of 59.58 % compared to the control. Therefore, the antiviral efficacy of synthesized CuO nanoparticles against plant viruses was established, supporting their potential as a novel strategy for plant management.