Optimization and Characterization of Silver Nanoparticles Synthesized by Celosia cristata and Their Potential Application as Antimicrobial Agent against Plant Pathogens

Background: As a need of hour around the globe for attaining sustainable solutions, the present investigation validates an easy, economical and time-efficient method to produce silver nanoparticles by natural plant leaf extract of Celosia cristata. Methods: The silver nanoparticles were synthesized and further characterized by visual observation, UV-Vis spectrophotometer, XRD, FTIR and TEM. The response surface methodology was utilized to optimize the operational conditions that prescribe a mixture of 12.5 ml Celosia cristata leaf extract and 87.5 ml 10 mM silver nitrate, to be kept at 37.5° for 120 minutes. Result: The change in colour of plant extract on adding precursor from yellow to brown colour indicates nanoparticles synthesis, which on UV-Vis spectrophotometer shows relevant peak at 424 nm. The X-ray diffraction peaks at 38°, 44°, 64° and 77° correspond to the hkl of (111), (200), (220) and (311) respectively that displays the crystal nature of silver nanoparticle. Fourier transform infrared spectroscopy indicated the presence of alkanes, alkynes, amines, carboxyl groups and methylene compounds functional groups in silver nanoparticles. Transmission electron microscope image depicted their spherical shapes with average nanoparticle size of 22 nm, which were found to be anti-microbial with minimum inhibitory concentration of 0.1562, 0.3125 and 0.625 against Alternaria solani, Fusarium graminearum and Xanthomonas oryzae which are potential plant pathogens. The present work concludes the antimicrobial efficacy of nanoparticles and RSM method to be an efficient tool for detecting the optimized synthesis parameter.