A Novel Green Synthesis of Silver Nanoparticles Using Rubus crataegifolius Bge Fruit Extract

Catalytic Degradability of p-Nitrophenol Using Ecofriendly Silver Nanoparticles

In an effort to produce non-toxic and economically viable “green” protocols for waste water treatment, researchers are actively involved to develop versatile and effective silver nanoparticles (SNPs) as nano-catalyst from bio-based techniques. Since, p-nitrophenol (PNP) is one of the anthropogenic contaminants, considerable attention has been focused in catalytic degradability of PNP in wastewater treatment by curtailing serious effect on aquatic fauna. Ingestion of contaminants by aquatic organisms will not only affect the aquatic species but is also a potential threat to human health, especially if the toxic contaminants are involved in food chain. In this short report, we provided a comprehensive insight on few remarkable nanocatalysts especially based on SNPs and its biopolymer composites synthesized via ecofriendly “green” route. The beneficiality and catalytic performance of these silver nanocatalysts are concisely documented on standard model degradation reduction of PNP to p-aminophenol (PAP) in the presence of aqueous sodium borohydride. The catalytic degradation of PNP to PAP using SNPs follows pseudo first order kinetics involving six-electrons with lower activation energy. Furthermore, we provided a list of highly effective, recoverable, and economically viable SNPs, which demonstrated its potential as nanocatalysts by focusing its technical impact in the area of water remediation.

Larvicidal Activity of Synthesized Silver Nanoparticles from Curcuma zedoaria Essential Oil against Culex quinquefasciatus

Culex quinquefasciatus is the major vector of the bancroftian filarial parasite which causes human lymphatic filariasis and St. Louis encephalitis. The simple way to stop the transmission is to control the vector by using synthetic chemicals. However, herbal essential oils have biological properties, such as a larvicidal effect and are ecofriendly to use. In this study, we investigated the larvicidal activity of Curcuma zedoaria essential oil (ZEO) and biosynthesized silver nanoparticles using this essential oil (ZEO-AgNPs). The larvicidal activity against both insecticide-susceptible and -resistant strains of Cx. quinquefasciatus larvae of ZEO were investigated and compared with ZEO-AgNPs. The ZEO-AgNPs showed the utmost toxicity against both strains of Cx. quinquefasciatus. After 24 h of exposure, LC₅₀ and LC₉₉ of ZEO against susceptible strain were 36.32 and 85.11 ppm, respectively. While LC₅₀ and LC₉₉ of ZEO against the resistant strain were 37.29 and 76.79 ppm, respectively. Whereas ZEO-AgNPs offered complete larval mortality within 24 h of exposure, LC₅₀ and LC₉₉ of ZEO-AgNPs against the susceptible strain, were 0.57 and 8.54 ppm, respectively. For the resistant strain, LC₅₀ and LC₉₉ values were 0.64 and 8.88 ppm, respectively. The potency in killing Cx. quinquefasciatus and stability of ZEO-AgNPs have made this product a good candidate for the development of novel natural larvicides.

Larvicidal and pupicidal evaluation of silver nanoparticles synthesized using Aquilaria sinensis and Pogostemon cablin essential oils against dengue and zika viruses vector Aedes albopictus mosquito and its histopathological analysis

Mosquitoes pose a threat to humans and animals, causing millions of deaths every year. Vector control by effective eco-friendly pesticides of natural origin is a serious issue that requires urgent attention. The employment of green-reducing extracts for nanoparticles biosynthesis in a rapid and single-step process represents a promising strategy. In this study, silver nanoparticles (AgNPs) were biofabricated using an essential oil of Aquilaria sinensis (AsEO) and Pogostemonis Herba essential oil of Pogostemon cablin (PcEO) in one step and cost-effective manner. UV-vis spectrophotometry, Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, X-ray diffraction analysis and energy-dispersive X-ray spectroscopy were used to confirm the AgNPs formation and their biophysical characterization. The larvicidal and pupicidal toxicity of AsEO, PcEO and biosynthesized AgNPs were evaluated against larvae and pupae of the dengue and Zika virus vector Aedes albopictus. Compared to the tested essential oils, the biofabricated AgNPs showed the highest toxicity against larvae and pupae of Ae.albopictus. In particular, the LC₅₀ values of AsEO ranged from 44.23 (I) to 166 (pupae), LC₅₀ values of PcEO ranged from 32.49 (I) to 90.05(IV), LC₅₀ values of AsEO-AgNPs from 0.81 (I) to 1.12 (IV) and LC₅₀ values of PcEO-AgPNs from 0.85 (I) to 1.19 (IV). Furthermore, histological analysis of the midgut cells of the control and treated larvae exhibited that the epithelial cells and brush border were highly affected by the fabricated AgNPs compared to the essential oils (AsEO and PcEO). Overall, the A. sinensis and P. cablin essential oils fabricated AgNPs have a potential of application as a biopesticide for mosquito control through safer and cost-effective approach.