Biosynthesised silver nanoparticle with Rhizophora annamalayana mangrove leaf aqueous extract and its larvicidal activity: An in-vitro study

Plant extracts have been used as both reducing and capping agents, which has helped make the production of silver nanoparticles (AgNPs) more eco-friendly. Following a 30-minute treatment with aqueous leaf extracts, a change in color was evident, indicating the formation of silver nanoparticles (AgNPs). Moreover, the confirmation was achieved by analyzing data acquired from a range of analytical techniques, such as the UV-visible spectrum, Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Scanning Electron Microscopy (SEM). The larvicidal activity of these silver nanoparticles (AgNPs) was evaluated against the third instar and fourth larvae of Aedes aegypti in the present study. The results indicated that the larvae displayed a reaction that differed depending on the dosage, with AgNPs at 20 mL demonstrating the most notable effect on mortality rates. More precisely, when the concentration was 90 μg/mL, the mortality rate was 84% for 3rd instar larvae and 87.33% for 4th instar larvae. In contrast, the concentration of 12.5 μg/mL resulted in the lowest amount of activity, specifically 12.67%, on 3rd instar larvae. This phenomenon can be attributed to the likelihood of the radicals forming chelation bonds on the extensive surface area of the nanoparticles. The study demonstrates the potential use of R. annamalayana-mediated AgNPs as highly effective larvicidal agents for the development of innovative nanoparticle-based biological treatments.