Biosynthesis, Characterization and Anti-dengue vector activity of Silver Nanoparticles prepared by Azadirachta indica and Citrullus colocynthis

<p><span>Here, we report biosynthesis of silver nanoparticles (AgNPs) using aqueous extracts of (i) <i>Azadirachta indica</i> leaves and (ii) <i>Citrullus colocynthis</i> fruit and their larvicidal activity against <i>Aedes aegypti.</i> The Uv-Vis spectroscopy absorption peaks occurred in range 412-416 nm for <i>A. indica</i> AgNPs and 416-431nm for <i>C. </i><i>colocynthis</i> AgNPs indicating the silver nature of prepared colloidal samples. The Scanning electron microscopy examination revealed the spherical morphology of both types of NPs with average size of 17±4 nm (<i>A. indica</i> AgNPs) and 26±5 nm (<i>C. </i><i>colocynthis</i> AgNPs). The x-ray diffraction pattern confirmed the face centred cubic (FCC) structure with crystallite size of 11±1 nm (<i>A. indica</i> AgNPs) and 15±1 nm (<i>C. </i><i>colocynthis</i> AgNPs) while characteristic peaks appearing in Fourier transform infrared spectroscopy analysis indicated the attachment of different biomolecules on AgNPs.. The larvicidal activity at different concentrations of synthesized AgNPs (1-20 </span>mg/L<span>) and extracts (0.5 % - 1.5 %) against <i>Aedes aegypti</i> was examined for 24 h. A concentration dependent larvicidal potential of both types of AgNPs was observed. The LC₅₀values were found to be 0.3 mg/L and 1.25 mg/L for <i>C. colocynthis</i> AgNPs and <i>A. indica</i> AgNPs respectively. However, extracts did not exhibit any notable larvicidal activity.</span></p>