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)

Tiny Green Army: Fighting Malaria with Plants and Nanotechnology

Malaria poses a global threat to human health, with millions of cases and thousands of deaths each year, mainly affecting developing countries in tropical and subtropical regions. Malaria's causative agent is Plasmodium species, generally transmitted in the hematophagous act of female Anopheles sp. mosquitoes. The main approaches to fighting malaria are eliminating the parasite through drug treatments and preventing transmission with vector control. However, vector and parasite resistance to current strategies set a challenge. In response to the loss of drug efficacy and the environmental impact of pesticides, the focus shifted to the search for biocompatible products that could be antimalarial. Plant derivatives have a millennial application in traditional medicine, including the treatment of malaria, and show toxic effects towards the parasite and the mosquito, aside from being accessible and affordable. Its disadvantage lies in the type of administration because green chemical compounds rapidly degrade. The nanoformulation of these compounds can improve bioavailability, solubility, and efficacy. Thus, the nanotechnology-based development of plant products represents a relevant tool in the fight against malaria. We aim to review the effects of nanoparticles synthesized with plant extracts on Anopheles and Plasmodium while outlining the nanotechnology green synthesis and current malaria prevention strategies.

Silver Nanoparticles as an Intracanal Medicament: A Scoping Review

Silver nanoparticles (AgNPs) release Ag ions with potent bactericidal and anti-inflammatory effects. They have shown promising results as an intracanal medicament for removing Enterococcus faecalis (E. faecalis), a resistant bacterium associated with root canal failures. This review summarizes the role of AgNPs as an intracanal medicament. Original research articles on AgNPs as an intracanal medicament were searched in databases such as MEDLINE (PubMed), Scopus, and Embase, resulting in 24 studies. They showed that AgNPs effectively eliminated E. faecalis and reduced postoperative pain following root canal therapy. However, these effects should be further verified through clinical trials as most of the studies were in vitro.

Mosquito-Borne Diseases and Their Control Strategies: An Overview Focused on Green Synthesized Plant-Based Metallic Nanoparticles

Mosquitoes act as vectors of pathogens that cause most life-threatening diseases, such as malaria, Dengue, Chikungunya, Yellow fever, Zika, West Nile, Lymphatic filariasis, etc. To reduce the transmission of these mosquito-borne diseases in humans, several chemical, biological, mechanical, and pharmaceutical methods of control are used. However, these different strategies are facing important and timely challenges that include the rapid spread of highly invasive mosquitoes worldwide, the development of resistance in several mosquito species, and the recent outbreaks of novel arthropod-borne viruses (e.g., Dengue, Rift Valley fever, tick-borne encephalitis, West Nile, yellow fever, etc.). Therefore, the development of novel and effective methods of control is urgently needed to manage mosquito vectors. Adapting the principles of nanobiotechnology to mosquito vector control is one of the current approaches. As a single-step, eco-friendly, and biodegradable method that does not require the use of toxic chemicals, the green synthesis of nanoparticles using active toxic agents from plant extracts available since ancient times exhibits antagonistic responses and broad-spectrum target-specific activities against different species of vector mosquitoes. In this article, the current state of knowledge on the different mosquito control strategies in general, and on repellent and mosquitocidal plant-mediated synthesis of nanoparticles in particular, has been reviewed. By doing so, this review may open new doors for research on mosquito-borne diseases.

Synthesis, characterization, antimicrobial activity, and toxicity evaluation of aminolevulinic acid-silver and silver-iron nanoparticles for potential applications in agriculture

Aminolevulinic acid (ALA) is considered one of the most critical plants growth regulators and essential precursors for chlorophyll biosynthesis; besides, its photodynamic activity can be used to exterminate larvae and microorganisms in plants and soil. Silver nanoparticles (AgNPs) have unique physicochemical properties and potent antimicrobial, antiviral, and antifungal activities, and in agriculture, their application as nanopesticides has been proposed. In this study, silver and silver–iron nanoparticles capped/stabilized with aminolevulinic acid (ALAAgNPs and ALAAgFeNPs) were synthesized by the photoreduction method and characterized by UV-vis spectroscopy, transmission electron microscopy, and zeta potential analysis. The kinetics of ¹O₂ generation from ALAAgFeNPs were obtained. The ALANP toxicity was evaluated on stalks of E. densa by observing cell morphology changes and measuring chlorophyll content compared with water-treated plants. Antimicrobial activity was tested against E. coli, P. aeruginosa, and Candida albicans. The results suggested that ALANPs (prepared with [AgNO₃] ≤ 0.2 mM and [ALA] ≤ 0.4 mM) could be suitable for applications in the agricultural sector. The presence of ∼0.3 mmol of iron in ALAAgNPs synthesis increased cell uptake and chlorophyll synthesis.

ALA is a natural metabolite in all living cells and possesses low toxicity. ALANPs exhibit high antimicrobial activity, promote plant growth and have the potential to show photodynamic herbicidal properties under solar illumination.

Green Synthesis of Selenium Nanoparticles Mediated by Nilgirianthus ciliates Leaf Extracts for Antimicrobial Activity on Foodborne Pathogenic Microbes and Pesticidal Activity Against Aedes aegypti with Molecular Docking

The present study deals with the synthesis of selenium nanoparticles (SeNPs) using Nilgirianthus ciliatus leaf extracts, characterized by UV-Vis spectrophotometer, XRD, FTIR, FE-SEM, HR-TEM, DLS, and zeta potential analysis. The antimicrobial activity against Staphylococcus aureus (MTCC96), Escherichia coli (MTCC443), and Salmonella typhi (MTCC98) showed the remarkable inhibitory effect at 25 µl/mL concentration level. Furthermore, the characterized SeNPs showed a great insecticidal activity against Aedes aegypti in the early larval stages with the median Lethal Concentration (LC₅₀) of 0.92 mg/L. Histopathological observations of the SeNPs treated midgut and caeca regions of Ae. aegypti 4th instar larvae showed damaged epithelial layer and fragmented peritrophic membrane. In order to provide a mechanistic approach for further studies, molecular docking studies using Auto Dock Vina were performed with compounds of N. ciliatus within the active site of AeSCP2. Overall, the N. ciliates leaf-mediated biogenic SeNPs was promisingly evidenced to have potential larvicidal and food pathogenic bactericidal activity in an eco-friendly approach.

Larvicidal Activity of Carbon Black against the Yellow Fever Mosquito Aedes aegypti

Simple Summary

Nanoparticles have previously shown potential to control mosquito vectors. The present study examined whether carbon black, an industrial source of carbon-based nanoparticles (CNPs), was toxic to larvae of the yellow fever mosquito (Aedes aegypti). We found that exposing the first developmental stages of mosquito larvae to a modified form of carbon black EMPEROR^® 1800 (E1800), caused concentration-dependent mortality within 48 h of exposure; however, the development of larvae exposed to sub-lethal concentrations of E1800 was not disrupted. Analyses of E1800 suspensions suggest this carbon black forms CNPs that coalesce into larger aggregations. Microscopic observations of dead larvae showed the presence of CNP aggregations in the digestive tract and on external structures associated with swimming, breathing, and food uptake. Our results suggest carbon black is a source of CNPs that may have potential use for treating sources of standing water that mosquitoes use as breeding sites.

Abstract

The yellow fever mosquito Aedes aegypti is one of the deadliest animals on the planet because it transmits several medically important arboviruses, including Zika, chikungunya, dengue, and yellow fever. Carbon-based nanoparticles (CNPs) derived from natural sources have previously been shown to have toxic effects on mosquito larvae and offer a potential alternative to chemical insecticides such as pyrethroids, for which mosquitoes have evolved resistance. However, CNPs derived from industrial sources, such as carbon black, have not previously been evaluated as larvicides. Here, we evaluate the effects of a commercially-available carbon black, EMPEROR^® 1800 (E1800), on mortality and development of pyrethroid-susceptible (PS) and pyrethroid-resistant (PR) strains of Ae. aegypti. We found that E1800 exhibited concentration-dependent mortality against 1st instar larvae of both strains within the first 120 h after exposure, but after this period, surviving larvae did not show delays in their development to adults. Physical characterization of E1800 suspensions suggests that they form primary particles of ~30 nm in diameter that fuse into fundamental aggregates of ~170 nm in diameter. Notably, larvae treated with E1800 showed internal accumulation of E1800 in the gut and external accumulation on the respiratory siphon, anal papillae, and setae, suggesting a physical mode of toxic action. Taken together, our results suggest that E1800 has potential use as a larvicide with a novel mode of action for controlling PS and PR mosquitoes.

Synthesis and Antibacterial Activity of Silver Nanoparticles Against Escherichia coli and Pseudomonas sp

Silver nanoparticles (AgNPs) have been synthesized by chemical reduction method using ascorbic acid as reducing agent. Silver nitrate (AgNO[Formula: see text] and sodium dodecyl sulfate (SDS) have been used as precursor and stabilizer, respectively. The prepared samples were characterized by UV-visible spectroscopy, scanning electron microscopy (SEM) and X-ray diffraction (XRD). The antibacterial activity of prepared silver nanoparticles has been assessed by using the disc diffusion method against pathogenic, gram-negative bacterial strains including Escherichia coli and Pseudomonassp. To evaluate the potential antibacterial properties of AgNPs, the discs have been impregnated and dried with three different doses like 50, 100 and 150[Formula: see text][Formula: see text]l of 20[Formula: see text][Formula: see text]g/ml concentrated AgNPs solution and placed on the Petri-dishes. The antibiotic kanamycin (5[Formula: see text][Formula: see text]g) was used as control. In all the cases, a clear and distinct zone of inhibition is observed, which suggests that AgNPs can be used as effective growth inhibitors of various bacterial species and would be promising candidate for future development of antibacterial agents.

Enhanced mosquitocidal efficacy of pyrethroid insecticides by nanometric emulsion preparation towards Culex pipiens larvae with biochemical and molecular docking studies

BACKGROUND

The growing threat of vector-borne diseases and environmental pollution with conventional pesticides has led to the search for nanotechnology applications to prepare alternative products.

METHODS

In the current study, four pyrethroid insecticides include alpha-cypermethrin, deltamethrin, lambda-cyhalothrin, and permethrin were incorporated into stable nanoemulsions. The optimization of nanoemulsions is designed based on the active ingredient, solvent, surfactant, sonication time, sonication cycle, and sonication energy by factorial analysis. The nanoscale emulsions' droplet size and morphology were measured by dynamic light scattering (DLS) and transmission electron microscopy (TEM), respectively. The toxicity of nanoemulsions against Culex pipiens larvae was evaluated and compared with the technical and commercial formulations. The in vitro assay of adenosine triphosphatase (ATPase), carboxylesterase (CaE), and glutathione-S-transferase (GST) were also investigated. Furthermore, molecular docking was examined to assess the binding interactions between the tested pyrethroids and the target enzymes. Also, an ecotoxicological assessment of potential effects of the tested products on the freshwater alga Raphidocelis subcapitata was determined according to OECD and EPA methods. The emulsifible concentration (EC50) and NOEC (no observed effect concentration) values were estimated for each insecticide and graded according to the GHS to determine the risk profile in aquatic life.

RESULTS

The mean droplet diameter and zeta potential of the prepared pyrethroid nanoemulsions were found to be in the range of 72.00-172.00 nm and - 0.539 to - 15.40 mV, respectively. All insecticides' nanoemulsions showed significantly high toxicity (1.5-2-fold) against C. pipiens larvae compared to the technical and EC. The biochemical activity data proved that all products significantly inhibited ATPase. However, GST and CaE were significantly activated. Docking results proved that the pyrethroids exhibited a higher binding affinity with CaE and GST than ATPase. The docking scores ranged from - 4.33 to - 10.01 kcal/mol. Further, the biosafety studies of the nanopesticides in comparison with the active ingredient and commercial EC were carried out against the freshwater alga R. subcapitata and the mosquitocidal concentration of nanopesticides was found to be non-toxic.

CONCLUSION

The mosquitocidal efficacy of nano-pyrethroids formulated in a greener approach could become an alternative to using conventional pesticide application in an environmentally friendly manner.

Preparation, characterisation and comparative toxicity of nanopermethrin against Anopheles stephensi and Culex pipiens

OBJECTIVES

To assess the effectiveness of nanopermethrin as a potential new formulation for pest and vector control.

METHODS

Permethrin nanoparticles were prepared by the ionic gelation method and its structure and the formulations were designed using Box-Behnken statistical technique. The effect of independent variables (Chitosan/Permethrin ratio, tripolyphosphate quantity, sonication time) on the properties of nanoparticles was investigated to determine the optimal formulation.

RESULTS

The size of the nanoparticles ranged from 135.27 ± 5.88 to 539.5 ± 24.01 nm and the insecticide entrapment efficiency per cent (EE%) ranged from 7.72 ± 1.36 to 63.59 ± 3.17%. Anopheles stephensi larvae were then bioassayed with the nanopermethrin and compared with the results of the bioassay with the mother molecule of permethrin using a standard WHO-recommended mosquito larval bioassay kit. LC₅₀ with permethrin and nanopermethrin on larvae of An. stephensi were 0.125 and 0.026 ppm showing a 4.8 times difference. The LC₅₀ for permethrin and nanopermethrin on Culex pipiens were 0.003 and 0.00032 ppm, respectively, showing a 9.4-fold difference.

CONCLUSION

Nanopermethrin is much more potent than its mother molecule against larvae of An. stephensi and Cx. pipiens.

Green-synthesized metal nanoparticles for mosquito control: A systematic review about their toxicity on non-target organisms

Studies capturing the high efficiency of green-synthesized metal nanoparticles (NPs) in targeting mosquito vectors of the world's main infectious diseases suggest the NPs' possible utilization as bio-insecticides. However, it is necessary to confirm that these potential bio-insecticides are not harmful to non-target organisms that are often sympatric and natural enemies of the vectors of these diseases. In this systematic review, we comprehensively analyse the content of 56 publications focused on the potentially deleterious effects of NPs on these non-target organisms. Current research on biosynthesised NPs, characterization, and impact on mosquito vectors and non-target larvivorous organisms is reviewed and critically discussed. Finally, we pinpoint some major challenges that merit future investigation. Plants (87.5%) were mainly used for synthesizing NPs in the studies. NPs were found to be spherical or mainly spherical in shape with a large distribution size. In most of the included studies, NPs showed interesting mosquitocidal activity (LC₅₀ < 50 ppm). Some plant families (e.g., Meliaceae, Poaceae, Lamiaceae) have produced NPs with a particularly high larvicidal and pupicidal activity (LC₅₀ < 10 ppm). Regarding non-target organisms, most of the studies concluded that NPs were safe to them, with boosted predatory activity in NP-treated milieu. In contrast, some studies reported NP-elicited adverse effects (i.e., genotoxic, nuclear, and enzymatic effects) on these non-target organisms. This review outlines the promising mosquitocidal effects of biosynthesized NPs, recognizing that NPs' potential usage is currently limited by the harm NPs are thought pose to non-target organism. It is of utmost importance to investigate green NPs to determine whether laboratory findings have applications in the real world.

Susceptibility of Culex quinquefasciatus (Say) Larvae to Methanolic Extracts of Annona reticulata

&lt;b&gt;Background and Objective:&lt;/b&gt; Environment pollution and resistance of many pests to the most frequently used chemical insecticides gave the rationale of altering to replace them with natural herbal extracts for pests and vector control. This study investigated the effect of methanolic extract of &lt;i&gt;Annona reticulata&lt;/i&gt; on the mortality and development of larvae of &lt;i&gt;Culex quinquefasciatus&lt;/i&gt;. &lt;b&gt;Materials and Methods:&lt;/b&gt; Methanolic herbal extracts were analyzed using Reverse-Phase High-Performance Liquid Chromatography (RP-HPLC) to identify the phytochemical compounds in them. Ten mosquito larvae were used as replicates and exposed to each of the five concentrations of the plant extract (30, 100, 150, 200 and 250 mg mL&lt;sup&gt;1&lt;/sup&gt;) and ten larvae were exposed to double distilled water and considered as control. &lt;b&gt;Results:&lt;/b&gt; Phytochemical analysis revealed the presence of phenols, steroids, quinones, tannins and saponins. Statistical analysis showed a significant strong correlation and regression between exposure to the different concentrations of the extract and mortality of &lt;i&gt;Culex quinquefasciatus&lt;/i&gt; larvae where R&lt;sup&gt;2&lt;/sup&gt; = 0.982, the Correlation value is 0.991099 (p<0.05). Results also showed that the extracts affect the development of larvae more than mortality. The effect of the extracts on the early larval stages was significantly high compared to the late stages of larvae. &lt;b&gt;Conclusion:&lt;/b&gt; According to our knowledge results of this study has been reported for the first time in Saudi Arabia where &lt;i&gt;Annona reticulata&lt;/i&gt; is neglected regionally and no study approved its efficacy as a botanical herbal extract against mosquitoes.

Silver nanoparticles: Synthesis, medical applications and biosafety

Silver nanoparticles (AgNPs) have been one of the most attractive nanomaterials in biomedicine due to their unique physicochemical properties. In this paper, we review the state-of-the-art advances of AgNPs in the synthesis methods, medical applications and biosafety of AgNPs. The synthesis methods of AgNPs include physical, chemical and biological routes. AgNPs are mainly used for antimicrobial and anticancer therapy, and also applied in the promotion of wound repair and bone healing, or as the vaccine adjuvant, anti-diabetic agent and biosensors. This review also summarizes the biological action mechanisms of AgNPs, which mainly involve the release of silver ions (Ag+), generation of reactive oxygen species (ROS), destruction of membrane structure. Despite these therapeutic benefits, their biological safety problems such as potential toxicity on cells, tissue, and organs should be paid enough attention. Besides, we briefly introduce a new type of Ag particles smaller than AgNPs, silver Ångstrom (Å, 1 Å = 0.1 nm) particles (AgÅPs), which exhibit better biological activity and lower toxicity compared with AgNPs. Finally, we conclude the current challenges and point out the future development direction of AgNPs.

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.

In vitro anti-Pythium insidiosum activity of biogenic silver nanoparticles

Pythium insidiosum belongs to the phylum Oomycota. It is capable of infecting mammals causing a serious condition called pythiosis, which affects mainly horses in Brazil and humans in Thailand. The objective of the present study was to verify the in vitro anti-P. insidiosum activity of a biogenic silver nanoparticle (bio-AgNP) formulation. The in vitro assays were evaluated on P. insidiosum isolates (n = 38) following the M38-A2 protocol. Damage to the P. insidiosum hyphae ultrastructure was verified by means of scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Bio-AgNP inhibition concentrations on P. insidiosum isolates ranged from 0.06 to 0.47 μg/ml. It was observed through SEM that P. insidiosum hyphae treated showed surface roughness, as well as cell walls with multiple retraction areas, loss of continuity, and rupture in some areas. The TEM of treated hyphae did not differentiate organelle structures; also, the cellular wall was rarefied, showing wrinkled and partly ruptured borders. The bio-AgNP evaluated has excellent in vitro anti-P. insidiosum activity. However, further studies on its in vivo action are necessary as so to determine the possibility of its use in the treatment of the disease in affected hosts.

Evaluation of Pistia stratiotes fractions as effective larvicide against Anopheles mosquitoes

Mosquito are well-known vectors that cause diseases particularly malaria and filariasis which are detrimental to human health. These vectors occur mainly in tropical countries where more than 2 billion people live in endemic regions with about one million deaths been claimed yearly from malaria and filariasis. The study is aimed at evaluating the larvicidal activity of Pistia stratiotes fractions on Anopheles mosquitoes (Diptera: Culicidae). The ethyl acetate extract of P. stratiotes was obtained through percolation process and was chromatographed to yield nine fractions. The larvicidal activity of each of the nine fractions was tested in triplicates by exposing the larvae to 500, 250, 125, 62.5 and 31.3 µg/ml, respectively. Phytochemical screening of the nine fractions revealed the presence of alkaloids, flavonoids, glycosides and phlobatannins in varying quantities. The result obtained shows that fraction E has the highest lethal effect on the Anopheles larvae at LC₅₀ =14.81 µg/ml and was weakly effective at 602.03 µg/ml on brine shrimp larvae. The gas chromatography mass spectrometry analysis of fraction E revealed the presence of 35 pre-cursor compounds. Hence, ethyl acetate fractions of P. stratiotes could be an effective larvicide against Anopheles mosquito larvae as it has been found to be harmless to other aquatic organisms. Further work should be done on other aquatic weeds that have larvicidal potential to isolate the bioactive compounds.

Green synthesis of silver-nanoparticles from Annona reticulata leaves aqueous extract and its mosquito larvicidal and anti-microbial activity on human pathogens

Silver nanoparticles play a important role in controlling mosquito population as well as multi drug resistant pathogens without causing much harm to humans. In the present study was focused on green synthesis of silver nanoparticles against dengue causing vector (Aedes aegypti) and pathogens affecting humans. The synthesized silver nanoparticle was confirmed using UV- absorption spectrum range obtained at 416 nm, XRD, FTIR and HR-TEM analysis were used to determine the silver nanoparticle morphology and size with ∼6.48 ± 1.2-8.13 ± 0.18 nm and face centered cubic structure. The synthesized silver nanoparticles were exposed to fourth instar larvae of A. aegypti with different concentration (3-20 μg/mL) for 24 h and its elicit maximum mortality (100%) at their final concentration of 20 μg/mL and it's LC50 value was 4.43 μg/mL and LC90 value was 13.96 μg/mL, respectively. The minimum inhibitory activities of the tested pathogens were 125, 31.25, 62.5, 62.6 and 62.5 μg/mL for the Bacillus cereus, Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli and Candida albicans respectively. Further, the synthesized silver nanoparticle shows a potent antimicrobial activity against all tested pathogens. Moreover the effect of silver nanoparticle against Red Blood Cells belonging to 'O' positive blood group were tested and does not cause higher hemolysis to the cells even at the highest concentration. Based on these finding, we strongly suggested that face centered cubic structured A. reticulata AgNPs is an eco-friendly and potent bio-medical agent and can be apply in wide range of application an alternative chemically synthesized metal nanoparticle.

Biological nanopesticides: a greener approach towards the mosquito vector control

Mosquitoes, being a vector for some potentially dreadful diseases, pose a considerable threat to people all around the world. The control over the growth and propagation of mosquitoes comprises conventional pesticides, insect growth regulators and other microbial control agents. However, the usage of these common chemicals and conventional pesticides eventually has a negative impact on human health as well as the environment, which therefore becomes a major concern. The lacuna allows nanotechnology to come into action and exploit nanopesticides. Nanopesticides are majorly divided into two categories-synthetic and biological. Several nanoformulations serve as a promising nanopesticide viz. nanoparticles, e.g. biologically synthesised nanoparticles through plant extracts, nanoemulsions prepared using the essential oils like neem oil and citronella oil and nanoemulsion of conventional pesticides like pyrethroids. These green approaches of synthesising nanopesticides make use of non-toxic and biologically derived compounds and hence are eco-friendly with a better target specificity. Even though there are numerous evidences to show the effectiveness of these nanopesticides, very few efforts have been made to study the possible non-target effects on other organisms prevalent in the aquatic ecosystem. This study focuses on the role of these nanopesticides towards the vector control and its eco-safe property against the other non-target species.

Mosquito control with green nanopesticides: towards the One Health approach? A review of non-target effects

The rapid spread of highly aggressive arboviruses, parasites, and bacteria along with the development of resistance in the pathogens and parasites, as well as in their arthropod vectors, represents a huge challenge in modern parasitology and tropical medicine. Eco-friendly vector control programs are crucial to fight, besides malaria, the spread of dengue, West Nile, chikungunya, and Zika virus, as well as other arboviruses such as St. Louis encephalitis and Japanese encephalitis. However, research efforts on the control of mosquito vectors are experiencing a serious lack of eco-friendly and highly effective pesticides, as well as the limited success of most biocontrol tools currently applied. Most importantly, a cooperative interface between the two disciplines is still lacking. To face this challenge, we have reviewed a wide number of promising results in the field of green-fabricated pesticides tested against mosquito vectors, outlining several examples of synergy with classic biological control tools. The non-target effects of green-fabricated nanopesticides, including acute toxicity, genotoxicity, and impact on behavioral traits of mosquito predators, have been critically discussed. In the final section, we have identified several key challenges at the interface between "green" nanotechnology and classic biological control, which deserve further research attention.

Fabrication of highly effective mosquito nanolarvicides using an Asian plant of ethno-pharmacological interest, Priyangu (Aglaia elaeagnoidea): toxicity on non-target mosquito natural enemies

Mosquitoes threaten the lives of humans, livestock, pets and wildlife around the globe, due to their ability to vector devastating diseases. Aglaia elaeagnoidea, commonly known as Priyangu, is widely employed in Asian traditional medicine and pest control. Medicinal activities include anti-inflammatory, analgesic, anticancer, and anesthetic actions. Flavaglines, six cyclopenta[b]benzofurans, a cyclopenta[bc]benzopyran, a benzo[b]oxepine, and an aromatic butyrolactone showed antifungal properties, and aglaroxin A and rocaglamide were effective to control moth pests. Here, we determined the larvicidal action of A. elaeagnoidea leaf aqueous extract. Furthermore, we focused on Priyangu-mediated synthesis of Ag nanoparticles toxic to Culex quinquefasciatus, Aedes aegypti and Anopheles stephensi. The plant extract and the nanolarvicide were tested on three mosquito vectors, following the WHO protocol, as well as on three non-target mosquito predators. Priyangu-synthesized Ag nanoparticles were characterized by spectroscopic (UV, FTIR, XRD, and EDX) and microscopic (AFM, SEM, and TEM) analyses. Priyangu extract toxicity was moderate on Cx. quinquefasciatus (LC₅₀ 246.43; LC₉₀ 462.09 μg/mL), Ae. aegypti (LC₅₀ 229.79; LC₉₀ 442.71 μg/mL), and An. stephensi (LC₅₀ 207.06; LC₉₀ 408.46 μg/mL), respectively, while Priyangu-synthesized Ag nanoparticles were highly toxic to Cx. quinquefasciatus (LC₅₀ 24.91; LC₉₀ 45.96 μg/mL), Ae. aegypti (LC₅₀ 22.80; LC₉₀ 43.23 μg/mL), and An. stephensi (LC₅₀ 20.66; LC₉₀ 39.94 μg/mL), respectively. Priyangu extract and Ag nanoparticles were found safer to non-target larvivorous fishes, backswimmers, and waterbugs, with LC₅₀ ranging from 1247 to 37,254.45 μg/mL, if compared to target pests. Overall, the current research represents a modern approach integrating traditional botanical pesticides and nanotechnology to the control of larval populations of mosquito vectors, with negligible toxicity against non-target including larvivorous fishes, backswimmers, and waterbugs.

Nanosilver: new ageless and versatile biomedical therapeutic scaffold

Silver nanotechnology has received tremendous attention in recent years, owing to its wide range of applications in various fields and its intrinsic therapeutic properties. In this review, an attempt is made to critically evaluate the chemical, physical, and biological synthesis of silver nanoparticles (AgNPs) as well as their efficacy in the field of theranostics including microbiology and parasitology. Moreover, an outlook is also provided regarding the performance of AgNPs against different biological systems such as bacteria, fungi, viruses, and parasites (leishmanial and malarial parasites) in curing certain fatal human diseases, with a special focus on cancer. The mechanism of action of AgNPs in different biological systems still remains enigmatic. Here, due to limited available literature, we only focused on AgNPs mechanism in biological systems including human (wound healing and apoptosis), bacteria, and viruses which may open new windows for future research to ensure the versatile application of AgNPs in cosmetics, electronics, and medical fields.

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

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 (AgNO₃). 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 LC₅₀ values of 26.693, 1.113 and 0.610 μg/mL (3 mM AASE-AgNO₃) 9.119, 0.420 and 0.407 μg/mL (4 mM AASE-AgNO₃) and that of 4.283, 0.3 and 0.248 μg/mL (5 mM AASE-AgNO₃). 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.

Mosquito larvicidal activity of cadmium nanoparticles synthesized from petal extracts of marigold (Tagetes sp.) and rose (Rosa sp.) flower

Mosquitoes are blood-thirsty insects and serve as the most important vectors for spreading most notorious diseases such as malaria, yellow fever, dengue fever, and filariasis. The extensive use of synthetic mosquito repellent has resulted in resistance in mosquitoes. Therefore, the development of a reliable, eco-friendly processes for the synthesis of nano dimensional materials is an utmost important aspect of nanotechnology. In the present study, authors report absolute green synthesis of cadmium nanoparticles using marigold and rose flower petal extract. The characterization of nanomaterials was done by using UV-Vis, SEM, FTIR and fluorescent spectrophotometer analysis. Finally cadmium nanoparticles were also evaluated for their larvicidal activity of mosquito. Marigold flower petal extract shows 100 % mortality after 72 h of incubation with 10 ppm of Cd-nanoparticles. No mortality was observed in the control. Therefore, out of two flower petal mediated nanoparticles, only marigold showed better performance towards mosquito larvicidal activity than rose petal extracts. This is the first report on mosquito larvicidal activity of flower-petal mediated cadmium nanoparticles. Thus, the use of marigold petal extract to synthesize cadmium nanoparticles is a rapid, ecofriendly, and a single-step approach and the CdNps formed can be potential mosquito larvicidal agents.

Biosynthesis, Antibacterial Activity and Anticancer Effects Against Prostate Cancer (PC-3) Cells of Silver Nanoparticles Using Dimocarpus Longan Lour. Peel Extract

Metal nanoparticles, particularly silver nanoparticles (AgNPs), are developing more important roles as diagnostic and therapeutic agents for cancers with the improvement of eco-friendly synthesis methods. This study demonstrates the biosynthesis, antibacterial activity, and anticancer effects of silver nanoparticles using Dimocarpus Longan Lour. peel aqueous extract. The AgNPs were characterized by UV-vis absorption spectroscopy, X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), scanning electron microscopy (SEM), and Fourier transform infrared spectroscope (FTIR). The bactericidal properties of the synthesized AgNPs were observed via the agar dilution method and the growth inhibition test. The cytotoxicity effect was explored on human prostate cancer PC-3 cells in vitro by trypan blue assay. The expressions of phosphorylated stat 3, bcl-2, survivin, and caspase-3 were examined by Western blot analysis. The longan peel extract acted as a strong reducing and stabilizing agent during the synthesis. Water-soluble AgNPs of size 9-32 nm was gathered with a face-centered cubic structure. The AgNPs had potent bactericidal activities against gram-positive and gram-negative bacteria with a dose-related effect. AgNPs also showed dose-dependent cytotoxicity against PC-3 cells through a decrease of stat 3, bcl-2, and survivin, as well as an increase in caspase-3. These findings confirm the bactericidal properties and explored a potential anticancer application of AgNPs for prostate cancer therapy. Further research should be focused on the comprehensive study of molecular mechanism and in vivo effects on the prostate cancer.

Biosynthesis, characterization, and acute toxicity of Berberis tinctoria-fabricated silver nanoparticles against the Asian tiger mosquito, Aedes albopictus, and the mosquito predators Toxorhynchites splendens and Mesocyclops thermocyclopoides

Aedes albopictus is an important arbovirus vector, including dengue. Currently, there is no specific treatment for dengue. Its prevention solely depends on effective vector control measures. In this study, silver nanoparticles (AgNPs) were biosynthesized using a cheap leaf extract of Berberis tinctoria as reducing and stabilizing agent and tested against Ae. albopictus and two mosquito natural enemies. AgNPs were characterized by using UV–vis spectrophotometry, X-ray diffraction, and scanning electron microscopy. In laboratory conditions, the toxicity of AgNPs was evaluated on larvae and pupae of Ae. albopictus. Suitability Index/Predator Safety Factor was assessed on Toxorhynchites splendens and Mesocyclops thermocyclopoides. The leaf extract of B. tinctoria was toxic against larval instars (I–IV) and pupae of Ae. albopictus; LC50 was 182.72 ppm (I instar), 230.99 ppm (II), 269.65 ppm (III), 321.75 ppm (IV), and 359.71 ppm (pupa). B. tinctoria-synthesized AgNPs were highly effective, with LC50 of 4.97 ppm (I instar), 5.97 ppm (II), 7.60 ppm (III), 9.65 ppm (IV), and 14.87 ppm (pupa). Both the leaf extract and AgNPs showed reduced toxicity against the mosquito natural enemies M. thermocyclopoides and T. splendens. Overall, this study firstly shed light on effectiveness of B. tinctoria-synthesized AgNPs as an eco-friendly nanopesticide, highlighting the concrete possibility to employ this newer and safer tool in arbovirus vector control programs.

Green synthesis of silver nanoparticles from Cassia roxburghii-a most potent power for mosquito control

Mosquitoes transmit serious human diseases, causing millions of deaths every year. The use of synthetic insecticides to control vector mosquitoes has caused physiological resistance and adverse environmental effects in addition to high operational cost. Insecticides of synthesized natural products for vector control have been a priority in this area. In the present study, silver nanoparticles (AgNPs) synthesized using Cassia roxburghii plant leaf extract against Anopheles stephensi, Aedes aegypti, and Culex quinquefasciatus were determined. Larvae were exposed to varying concentrations of synthesized AgNPs (12, 24, 36, 48, and 60 μg/mL) and aqueous leaf extracts (60, 120, 180, 240, and 300 μg/mL) for 24 h. The synthesized AgNPs were characterized by UV-Vis spectrum, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), with energy-dispersive X-ray spectroscopy analysis (EDX), transmission electron microscopy, and X-ray diffraction analysis (XRD). Compare to aqueous extracted synthesized AgNPs showed extensive mortality rate against An. stephensi, Ae. aegypti, and C. quinquefasciatus with the LC50 and LC90 values that were 26.35, 28.67, 31.27 and 48.81, 53.24, and 58.11 μg/mL, respectively. No mortality was observed in the control. This is the first report on mosquito larvicidal activity of plant-synthesized nanoparticles. Thus, the use of C. roxburghii to synthesize silver nanoparticles is a rapid, eco-friendly, and a single-step approach, and the AgNPs formed can be potential mosquito larvicidal agents. Therefore, this study proves that C. roxburghii is a potential bioresource for stable, reproducible nanoparticle synthesis (AgNPs) and also can be used as an efficient mosquito control agent. This is the first report on the larvicidal activity of the plant extract and AgNPs.

Predation by Asian bullfrog tadpoles, Hoplobatrachus tigerinus, against the dengue vector, Aedes aegypti, in an aquatic environment treated with mosquitocidal nanoparticles

Aedes aegypti is a primary vector of dengue and chikungunya. The use of synthetic insecticides to control Aedes populations often leads to high operational costs and adverse non-target effects. Botanical extracts have been proposed for rapid extracellular synthesis of mosquitocidal nanoparticles, but their impact against predators of mosquito larvae has not been well studied. We propose a single-step method for the biosynthesis of silver nanoparticles (AgNP) using the extract of Artemisia vulgaris leaves as a reducing and stabilizing agent. AgNP were characterized by UV-vis spectroscopy, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and X-ray diffraction (XRD). SEM and XRD showed that AgNP were polydispersed, crystalline, irregularly shaped, with a mean size of 30-70 nm. EDX confirmed the presence of elemental silver. FTIR highlighted that the functional groups from plant metabolites capped AgNP, stabilizing them over time. We investigated the mosquitocidal properties of A. vulgaris leaf extract and green-synthesized AgNP against larvae and pupae of Ae. aegypti. We also evaluated the predatory efficiency of Asian bullfrog tadpoles, Hoplobatrachus tigerinus, against larvae of Ae. aegypti, under laboratory conditions and in an aquatic environment treated with ultra-low doses of AgNP. AgNP were highly toxic to Ae. aegypti larval instars (I-IV) and pupae, with LC50 ranging from 4.4 (I) to 13.1 ppm (pupae). In the lab, the mean number of prey consumed per tadpole per day was 29.0 (I), 26.0 (II), 21.4 (III), and 16.7 (IV). After treatment with AgNP, the mean number of mosquito prey per tadpole per day increased to 34.2 (I), 32.4 (II), 27.4 (III), and 22.6 (IV). Overall, this study highlights the importance of a synergistic approach based on biocontrol agents and botanical nano-insecticides for mosquito control.