Studies on the impact of biosynthesized silver nanoparticles (AgNPs) in relation to malaria and filariasis vector contro
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ORIGINAL PAPER
Studies on the impact of biosynthesized silver nanoparticles (AgNPs) in relation to malaria and filariasis vector control against Anopheles stephensi Liston and Culex quinquefasciatus Say (Diptera: Culicidae) Selladurai Subarani & Selvi Sabhanayakam & Chinnaperumal Kamaraj
Received: 13 July 2012 / Accepted: 28 September 2012 / Published online: 12 October 2012 # Springer-Verlag Berlin Heidelberg 2012
Abstract Biosynthesized nanoparticles have been achieved using environmentally acceptable plant extract and ecofriendly reducing and capping agents. The present study was based on assessments of the larvicidal activities to determine the efficacies of synthesized silver nanoparticles (AgNPs) using aqueous leaf extract of Vinca rosea (L.) (Apocynaceae) against the larvae of malaria vector Anopheles stephensi Liston and filariasis vector Culex quinquefasciatus Say (Diptera: Culicidae). Larvae were exposed to varying concentrations of aqueous extract of V. rosea and synthesized AgNPs for 24, 48, and 72 h. AgNPs were rapidly synthesized using the leaf extract of V. rosea, and the formation of nanoparticles was observed within 15 min. The results recorded from UV–Vis spectrum, Fourier transform infrared (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) support the biosynthesis and characterization of AgNPs. The formation of the AgNPs synthesized from the XRD spectrum compared with the Bragg reflections at 2θ029.36, 38.26, 44.51, 63.54, and 77.13° which can be indexed to the (121), (111), (200), (220), and (311) orientations, respectively, confirmed the presence of AgNPs. The FTIR spectra of AgNPs exhibited prominent S. Subarani : S. Sabhanayakam (*) Department of Zoology, Annamalai University, Annamalai Nagar 608 002 Tamil Nadu, India e-mail: [email protected] C. Kamaraj Post Graduate and Research Department of Zoology, C. Abdul Hakeem College, Melvisharam, 632 509, Vellore District Tamil Nadu, India
peaks at the spectra showed sharp and strong absorption band at 3,406.71 to 3,431.90 cm−1 double in case of NH2 group of a primary amine (N–H stretch). The presence of the sharp peak at 2,926.54 to 2,925.80 cm−1 very broad often looks like distorted baseline (O–H carboxylic acids). The band 1,633.26 to 1,625.81 cm−1 was assigned to C 0C alkenes, aromatic ring stretching vibration, respectively. SEM analysis of the synthesized AgNPs clearly showed the clustered and irregular shapes, mostly aggregated and having the size of 120 nm. TEM reveals spherical shape of synthesized AgNPs. Particle size analysis revealed that the size of particles ranges from 25 to 47 nm with average size of 34.61 nm. Energy-dispersive X-ray spectroscopy showed the complete chemical composition of the synthesized AgNPs. In larvicidal activity, the results showed that the maximum efficacy was observed in synthesized AgNPs against the fourth instar larvae of A. stephensi (LC50 0 12.47 and 16.84 mg/mL and LC90 036.33 and 68.62 mg/ mL) on 48 and 72 h of exposure and against C. qu
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