Phytosynthesis of silver nanoparticles using Halocharis sulphurea (Moq.) Moq. extract and their antimicrobial, antioxidant and aphicidal activities

Researchers are synthesizing metallic nanoparticles by using numerous synthesis methods. Biosynthesis of silver nanoparticles by using plants (phytosynthesis) is an efficient, environmentally friendly, and cost effective alternative of chemical and physical methods. Presently phytosynthesized silver nanoparticles have gained interest due to their medicinal properties and various industrial applications. Halocharis sulphurea ( H. sulphurea ) is a medicinal plant and used in the treatment of different diseases. Therefore, the present study tested H. sulphurea derived silver nanoparticles (HAgNps) for antimicrobial, antioxidant and aphicidal activities. The HAgNps were successfully synthesized by treating 0.001 mM solution of silver nitrate (5 mL) with 500 µl extract of H. sulphurea (2% HSE) by retaining synthesis temperature at 55 ^o C, pH 11, and incubation time 24 hours. The formation of HAgNps was visually authenticated when color of the reaction mixture changed to brown, which was further confirmed by UV-visible spectrophotometry. The morphological parameters of the HAgNps were confirmed by using a different analytic techniques. The HAgNps were further tested for in vitro antimicrobial, antioxidant and aphicidal properties. Under optimum reaction conditions, the UV-visible spectrophotometry showed a sharp absorption peak at 420 nm wavelength which is characteristic peak of HAgNps. The XRD crystallography confirmed crystalline structure of the HAgNps having average crystalline size 55.33 nm. The SEM analysis revealed random shaped HAgNps. The EDX spectrum revealed the presence of Ag and O atoms in the green synthesized materials. The HAgNps at 100 mg/10 mL concentration showed zones of growth inhibition 22.67 mm, 22.66 mm and 19 mm against S. aureus, E. coli and K. pneumonia . The HAgNps proved antifungal agents against A. niger, R. solani and F. solani and their antifungal activity was highly comparable to terbinafine. Results of aphicidal activity showed that both the HAgNps and insecticide imidacloprid significantly decreased (p<0.05) the L. erysimi population after 24 hours of application. The LD50 values calculated for HAgNps and imidacloprid were 29.684 mg/mL and 1.641 µL/mL. It was concluded that H. sulphurea derived silver nanoparticles has potential antimicrobial, antioxidant and aphicidal activities.