Cullen corylifolium (L.) Medik. Seed Extract, an Excellent System For Fabrication of Silver Nanoparticles and Their Multipotency Validation Against Different Mosquito Vectors and Human Cervical Cancer Cell Line

Mosquito larvicidal potential of Solanum xanthocarpum leaf extract derived silver nanoparticles and its bio-toxicity on non-target aquatic organism

BACKGROUND & OBJECTIVES

Mosquitoes are insects of public health importance that act as a vector to transmit various vector-borne diseases in humans including dengue, malaria, filariasis and yellow fever. The continually employed synthetic insecticides have developed resistance in mosquitoes. Nano-based botanical insecticides can be considered as the best alternative due to several advantages like being simple, non-pathogenic, biodegradable and safe to the environment. The present work reported the maximum larvicidal potential of green synthesized silver nanoparticles (AgNPs) derived from the leaf extract of Solanum xanthoearpum against the third instar larvae of Anopheles stephensi, Aedes aegypti, and Culex quinquefasciatus over its crude leaf extract.

METHODS

The synthesis of AgNPs was done by adding leaf extract into silver nitrate solution in a conical flask. The characterization of AgNPs was done using different techniques such as UV-Vis, SEM, TEM, XRD, DLS and SAED. FT-IR analysis was done to find out the compound responsible for bio-reduction of silver nitrate. Larvicidal activity of AgNPs was checked against An. stephensi, Ae. aegypti, and Cx. quinquefasciatus according to WHO standard protocol and toxicity was evaluated against Poecilia reticulate.

RESULTS

A change in colour was observed indicating the synthesis of AgNPs which was further confirmed by a strong surface plasmon resonance peak at 421nm under the UV-Vis spectrum. SEM and TEM micrographs exhibited that the most common shape of AgNPs was spherical. XRD spectrum showed crystalline nature of silver nanoparticles. FT-IR spectrum showed the presence of various functional groups such as carboxyl and hydroxyl which might be responsible for bio-reduction and capping of silver nanoparticles. Further, silver nanoparticles were very effective against An. stephensi, Ae. aegypti, and Cx. quinquefasciatus with LC₅₀ and LC₉₀ values of 1.90, 2.36, 2.93, 3.82, 4.31 and 7.63 ppm, respectively, as compared to aqueous leaf extract after 72 h of exposure and were non-toxic against non-target organism P. retieulata. Interpretation & eonelusion: From the above finding, it can be concluded that fabricated AgNPs can be promising eco-friendly tools for controlling mosquito vectors.

Fabrication and characterization of noble crystalline silver nanoparticles from Pimenta dioica leave extract and analysis of chemical constituents for larvicidal applications

The current works report the bio-efficacy of Pimenta dioica leaf derived silver nanoparticles (Pd@AgNPs) and leaf extract obtained trough different solvents against the larvae of malaria, filarial and dengue vectors. Synthesis of silver nanoparticles (AgNPs) was done by adding 10 ml of P. dioica leaf extract into 90 ml of 1 mM silver nitrate solution, a slow colour change was observed depicting the formation of AgNPs. Further, Pd@AgNPs was confirmed through Ultraviolet–visible spectroscopy which exhibited characteristic absorption peak at 422 nm wavelength. X-ray diffraction and selected area electron diffraction analysis confirmed monodispersed and crystalline nature of Pd@AgNPs with 32 nm an average size. Scanning electron microscopy and transmission electron microscopy showed the most of Pd@AgNPs were spherical and triangular in shape and energy-dispersive X-ray spectroscopy revealed silver elemental nature of nanoparticles. Zeta potential of Pd@AgNPs is highly negative which confirmed its stable nature. Pd@AgNPs showed prominent absorption peaks at 1015, 1047, 1243, 1634, 2347, 2373, 2697 and 3840 cm⁻¹ which are corresponding to following compounds polysaccharides, carboxylic acids, water, alcohols, esters, ethers, amines, amides and phenol, respectively as reported by Fourier-transform infrared spectroscopy analysis. Gas chromatography–mass spectrometry and Liquid chromatography–mass spectrometry analysis revealed 39 and 70 compounds, respectively, which might be contributed for bio-reduction, capping, stabilization and larvicidal behavior of AgNPs. A comparable lethality (LC₅₀ and LC₉₀) was observed in case of Pd@AgNPs over leaf extract alone. The potential larvicidal activity of Pd@AgNPs was observed against the larvae of Aedes aegypti,(LC_50, 2.605; LC_90, 5.084 ppm) Anopheles stephensi (LC_50, 3.269; LC_90, 7.790 ppm) and Culex quinquefasciatus (LC_50, 5.373; LC_90, 14.738 ppm without affecting non-targeted organism, Mesocyclops thermocyclopoides after 72 hr of exposure. This study entails green chemistry behind synthesis of AgNPs which offers effective technique for mosquito control and other therapeutic applications.

A potential role of green engineered TiO2 nanocatalyst towards enhanced photocatalytic and biomedical applications

This study demonstrates a simple protocol for phytofabrication of titanium dioxide nanoparticles (TiO₂NPs) wrapped with bioactive molecules from Ludwigia octovalvis leaf extract and their characterization by UV-visible absorption spectroscopy, Fourier transform spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), X-ray photoelectron spectrum (XPS), and diffuse reflectance spectrum (DRS). The bandgap energy of pure green engineered TiO₂ nanoparticles was determined by DRS analysis. The XPS analysis confirmed the purity of the TiO₂ nanoparticles. Results show that the synthesized TiO₂NPs were spherical in shape with the size ranged from 36 to 81 nm. The green engineered titanium oxide nanocatalyst exhibited enhanced rate of photocatalytic degradation of important textile toxic dyes namely crystal violet (93.1%), followed by methylene blue (90.6%), methyl orange (76.7%), and alizarin red (72.4%) after 6-h exposure under sunlight irradiation. Besides, this study determines the antimicrobial efficiency of TiO₂NPs (25 μl and 50 μl), leaf extract (25 μl), and antibiotic (25 μl) against clinically isolated human pathogenic bacterial strains namely Staphylococcus aureus, Klebsiella pneumoniae, Pseudomonas aeruginosa, Proteus vulgaris, Staphylococcus epidermidis, and Escherichia coli. Results show that maximum antibacterial activity with nanotitania treatment noticed was 21.6 and 18.3-mm inhibition in case of S. epidermis and P. aeruginosa, respectively. Enhanced rate of antibiofilm activity towards S. aureus and K. pneumoniae was also observed with TiO₂NPs exposure. The biomolecule loaded TiO₂NPs exhibited the fastest bacterial deactivation dynamics towards gram-negative bacteria (E. coli), with a complete bacterial inactivation within 105-min exposure. Interestingly, anticancer activity result indicates that percentage of human cervical carcinoma cell (HeLa) viability was negatively correlated with TiO₂NPs doses used. The AO/EtBr fluorescent staining result exhibited the occurrence of more apoptosis (dead cells) of HeLa cells due to the exposure of TiO₂NPs. Altogether, the present study clearly showed that biomolecules wrapped nanotitania could be used as effective and promising compound for enhanced photocatalytic and biomedical applications in the future.

Metal oxide nanoparticle synthesis (ZnO-NPs) of Knoxia sumatrensis (Retz.) DC. Aqueous leaf extract and It's evaluation of their antioxidant, anti-proliferative and larvicidal activities

In around the world, mosquito control is considered a most important because of the incapable of synthetic insecticides and the ecological pollution about by them. In this manner, need the eco-friendly insecticides to efficient control the mosquito disease is the need of the hour. We synthesized the eco-friendly of zinc oxide nanoparticles (ZnO-NPs) using the Knoxia sumatrensis aqueous leaf extract (Ks-ALE) as a reducing and stabilizing agent. The synthesis of ZnO-NPs was confirmed by UV with an absorption peak at 354 nm. ZnO-NPs crystal structure was analyzed by X-ray diffraction (XRD). Fourier transform infrared spectroscopy (FT-IR) spectra revealed the chloride, cyclic alcohols, sulfonamies, carboxylic acids, oximes, phosphines, alkenes and alcohol & phenol. Field emission-scanning electron microscopy (FE-SEM) showed that the NP's are rod shaped with 50-80 nm size and also energy dispersive spectra (EDaX) spectra showed presence of zinc. Antioxidant assay showed superior activity and evidenced by DPPH, ABTS and H2O2 radical assays. Furthermore, the ZnO-NPs exhibited strong activity in MCF-7 cell line with IC50 value is 58.87 μg/mL. Mosquito larvicidal activity of ZnO-NPs produced significant activity and excellent larvicidal activity was noticed in Cx. quinquefasciatus with LC50 0.08, mg/mL and LC9019.46 mg/mL. This study suggests that synthesized ZnO-NPs using Knoxia sumatrensis leaf extract have good biological activities and it makes them an ideal candidate for pharmacological studies.

Green synthesis of silver nanoparticles using Indian Belladonna extract and their potential antioxidant, anti-inflammatory, anticancer and larvicidal activities

Atropa acuminata aqueous leaf extract biosynthesized silver nanoparticles showed strong antioxidant, anticancerous (HeLa cells) and anti-inflammatory activities. Besides, this bio syn-AgNP also proved effective against mosquito vectors causing malaria, dengue and filariasis. Present study highlights eco-friendly and sustainable approach for the synthesis of silver nanoparticles (AgNP) using aqueous leaf extract of A. acuminata, a critically endangered medicinal herb. The addition of 1 mM silver nitrate to aqueous leaf extract resulted in the synthesis of AgNP when solution was heated at 60 °C for 30 min at pH 7. Absorption band at 428 nm, as shown by UV-Vis spectroscopy confirmed the synthesis of AgNP. XRD patterns revealed the crystalline nature of AgNP and TEM analysis showed that most of the nanoparticles were spherical in shape. Zeta potential of AgNP was found to be - 33.5 mV which confirmed their high stability. FT-IR investigations confirmed the presence of different functional groups involved in the reduction and capping of AgNP. The synthesized AgNP showed effective DPPH (IC₅₀-16.08 µg/mL), H₂O₂ (IC₅₀-25.40 µg/mL), and superoxide (IC₅₀-21.12 µg/mL) radical scavenging activities. These plant-AgNP showed significant inhibition of albumin denaturation (IC₅₀-12.98 µg/mL) and antiproteinase activity (IC₅₀-18.401 µg/mL). Besides, biosynthesized AgNP were found to have strong inhibitory effect against a cervical cancer (HeLa) cell line (IC₅₀-5.418 µg/mL) as well as larvicidal activity against 3rd instar larvae of Anopheles stephensi (LC₅₀-18.9 ppm, LC₉₀-40.18 ppm), Aedes aegypti (LC₅₀-12.395 ppm, LC₉₀-36.34 ppm) and Culex quinquefasciatus (LC₅₀-17.76 ppm, LC₉₀-30.82 ppm) and were found to be non-toxic against normal cell line (HEK 293), and a non-target organism (Mesocyclops thermocyclopoides). This is the first report on the synthesis of AgNP using aqueous leaf extract of A. acuminata, validating their strong therapeutic potential.

Biocontrol of mosquito vectors through herbal-derived silver nanoparticles: prospects and challenges

Mosquitoes spread several life-threatening diseases such as malaria, filaria, dengue, Japanese encephalitis, West Nile fever, chikungunya, and yellow fever and are associated with millions of deaths every year across the world. However, insecticides of synthetic origin are conventionally used for controlling various vector-borne diseases but they have various associated drawbacks like impact on non-targeted species, negative effects on the environment, and development of resistance in vector species by alteration of the target site. Plant extracts, phytochemicals, and their nanoformulations can serve as ovipositional attractants, insect growth regulators, larvicides, and repellents with least effects on the environment. Such plant-derived products exhibit broad-spectrum resistance against various mosquito species and are relatively cheaper, environmentally safer, biodegradable, easily accessible, and are non-toxic to non-targeted organisms. Therefore, in this review article, the current knowledge of phytochemical sources exhibiting larvicidal activity and their variations in response to solvents used for their extraction is underlined. Also, different methods such as physical, chemical, and biological for silver nanoparticle (AgNPs) synthesis, their mechanism of synthesis using plant extract, their potent larvicidal activity, and the possible mechanism by which these particles kill mosquito larvae are discussed. In addition, constraints related to commercialization of nanoherbal products at government and academic or research level and barriers from laboratory experiments to field trial have also been discussed. This comprehensive information can be gainfully employed for the development of herbal larvicidal formulations and nanopesticides against insecticide-resistant vector species in the near future. Graphical abstract.