Phyto-fabrication of brown seaweed Dictyota ciliolata extract towards silver nanoparticles synthesis and evaluation of mosquito-larvicidal potential of the synthesized AgNPs

Bio-fabrication of silver nanoparticles (AgNPs) was performed using the extracts of the brown seaweed Dictyota ciliolata (DC) and the resultant AgNPs were characterized by biophysical and chemical techniques. A prominent absorbance peak observed at 417 nm in the UV-Vis spectroscopy confirmed the presence of AgNPs. The FTIR spectrum revealed the presence of various functional groups at 2988.16, 1763.58, 1375.96, 1242.9 and 1055.84 cm^-1 which indicates their involvement in the stabilization of nanoparticles. XRD analysis showed the crystalline nature of DC-AgNPs. SEM analysis confirmed the presence of particles with an agglomerated clusters of micro flakes-like structure with the size range of 10 –120 nm. The weight percentage of elemental silver was determined as 54.96 % using the EDX analysis. DC-AgNPs showed potent larvicidal toxicity on the larvae of Anopheles stephensi, Aedes aegypti and Culex quinquefasciatus at first, second and third instars as well as against pupae stages when compared to the aqueous extract of D. ciliolata (DC-AE). The eco-toxicity assessment of the DC-AgNPs showed only very low toxicity against the non-target species, Artemia salina. The study results show the efficacy of the brown seaweed, D. ciliolata for the cost-effective and eco-friendly synthesis of AgNPs and their potential against mosquito-vectors.