A facile and rapid method for green synthesis of Achyranthes aspera stem extract-mediated silver nano-composites with cidal potential against Aedes aegypti L.

Abstract

Aedes aegypti L. is the primary vector associated with transmission of globally concerned diseases; Zika, yellow fever, dengue and Chikungunya. Present study investigates an efficient, alternative and comparative approach for mosquito control which is safe to environment and non-target organisms. The silver nano-composites ( AgNCs) were synthesized from the aqueous stem extract of Achyranthes aspera (AASE) using different concentration of aqueous silver nitrate (AgNO 3 ). The synthesis was tracked by UV-vis spectrophotometer and particle size analyser (DLS). The evaluation of their larvicidal potential against early fourth instars of Ae. aegypti showed significant potency, the toxicity increasing with the concentration of silver nitrate. The 24, 48 and 72 h bioassays resulted in respective LC 50 values of 26.693, 1.113 and 0.610 μg/mL (3 mM AASE-AgNO 3 ) 9.119, 0.420 and 0.407 μg/mL (4 mM AASE-AgNO 3 ) and that of 4.283, 0.3 and 0.248 μg/mL (5 mM AASE-AgNO 3 ). Keeping in view the significantly high larvicidal efficiency at lower concentration of silver nitrate, the 4 mM nano-composites were selected over 5 mM composites for further biophysical characterization carried out by X-ray Diffraction (XRD), Fourier transform infrared spectrometer (FTIR), Scanning electron microscopy (SEM), Energy dispersive X-ray (EDX) spectroscopy and Transmission electron microscopy (TEM). SEM and TEM confirmed the synthesis of spherical poly-dispersed AgNCs with average size ranging from 1–30 nm. Characterization through XRD showed the crystalline face-centered-cubic (fcc) structure of AgNCs with the highest intense peak obtained at 2θ value of 31.82°. FT-IR data suggests complex nature of AgNCs showing clearly defined peaks in different ranges. The present investigations recommend AgNCs of A. aspera stems as a low-cost and eco-friendly alternative to chemical insecticides for mosquito control.

Biogenic Synthesis of Silver Chloride Nanoparticles from Padina gymnospora and their Evaluation of Antimicrobial, Larvicidal, Hemolytic and Anticancer Activities.

“…By the accumulation of nanoparticles in the midgut region of mosquito, larva causes damage in the midgut, cortex region, and epithelial cells. Similar to seaweed mediated synthesis of nanoparticles, several plants mediated synthesized nanoparticles were shown in mosquito larval control [33]. Table 1 The larval bioassays performed by aqueous extract of P. gymnospora and green synthesized silver chloride nanoparticle AgClNPs act as an alternative source for microbial pathogens.…”

An Updated Review on Silver Nanoparticles in Biomedicine

“…Nanosilver-based formulations proved efficient therapeutic effects against several pathologies caused by clinically-relevant viruses, such as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) [ 211 , 212 ], human papilloma virus (HPV) [ 213 ], rotavirus [ 214 , 215 ] and other enteric viruses [ 216 , 217 , 218 ]. It is worth mentioning that new and effective platforms containing AgNPs were evaluated for their biocidal activity against viral vectors, generally mosquito-borne pathogens including Zika virus [ 219 , 220 ], Dengue virus [ 221 , 222 ], West Nile virus [ 223 , 224 ] and Chikungunya virus [ 225 , 226 ].…”

Formulation of Clitoria ternatea Leaves-mediated Silver Nanoparticles to Control Aedes aegypti Larvae

“…Comparable colour change from pale yellow to brownish has been documented while synthesizing silver nanoparticles from the leaves of A. aspera. 8,28 Such change in colour of the reaction mixture is proposed to be positively correlated with AgNO 3 concentration in the solution which led to the surface plasmon vibrations. 29,30 In addition, a specific combination of reductant volume, temperature and amount of NaOH resulted in a quick colour shift.…”

“…have been studied for the production of silver nanocomposites. 7,8 These formulations are cost and time-effective as well as environmentfriendly due to non-requirement of high pressure, energy, temperature and even toxic chemicals. 9 Hence nowadays, botanicals and their secondary metabolites, such as flavonoids, tannins, and ascorbic acid, etc.…”