Swift Fabrication of Silver Nanoparticles Using Bougainvillea glabra: Potential Against the Japanese Encephalitis Vector, Culex tritaeniorhynchus Giles (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.

Fabrication and evaluation of Dillenia indica-carrageenan blend hybrid superporous hydrogel reinforced with green synthesized MgO nanoparticles as an effective wound dressing material

An unexplored hybrid superporous hydrogel (MHSPH) of Dillenia indica fruit mucilage (DIFM) and carrageenan blend embedded with green synthesized magnesium oxide nanoparticles (MNPs) is utilized as an effective wound dressing material with appreciable mechanical strength in murine model. The prepared MNPs and the optimized MHSPH were characterized using X-ray diffraction (XRD), thermogravimetric analysis (TGA), Fourier transform infrared (FT- IR) spectroscopy. Size, zeta potential and morphology of MNPs was assessed using Dynamic light scattering technique (DLS) and field-emission scanning electron microscopy (FESEM) respectively. The MHSPH grades were further optimized using swelling study in phosphate buffer solution at pH 1.2, 7.0, and 8. Both MNPs and the optimized grade of MHSPH were evaluated based on hemolysis assay, and protein denaturation assays indicating them to be safe for biological use. Acute toxicity studies of the optimized MHSPH on Zebra fish model, revealed no observable toxic effect on the gill cells. Wound healing in Swiss albino mice with application of optimized grade of MHSPH took only 11 days for healing when compared to control mice where healing took 14 days, thus concluding that MHSPH as an effective dressing material as well as tissue regrowth scaffold.

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.

Ultra-sonication-enhanced green synthesis of silver nanoparticles using Barleria buxifolia leaf extract and their possible application

The main aim of the study, green route to the synthesis of silver nanoparticles (AgNPs) is a new technique that has recently gained popularity due to several advantages over conventional chemical methods. The objective of the study was focused on the green synthesis of AgNPs using Barleria buxifolia leaf extract via a rapid and eco-friendly ultrasonic-assisted technique. The obtained AgNPs were characterized using ultraviolet-visible (UV-Vis) absorption spectrum of the organically reduced silver showed a surface plasmon peak at 435 nm, characteristic for silver colloidal solutions. UV-Vis absorption spectrum, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy-dispersive X-ray spectroscopy (EDS) analysis showed that the obtained AgNPs were dispersed spheres with a uniform size of 80 nm. Furthermore, the Fourier-transform infrared spectroscopy (FTIR) and X-ray powder diffraction (XRD) analysis indicated that the surface of the obtained AgNPs was covered with organic molecules in plant extracts. Green synthesized AgNPs showed the highest antioxidant, antibacterial and anti-biofilm activity than a plant extract. In vitro anticancer assay demonstrated half-maximal inhibitory concentration (IC₅₀) values of 31.42, 30.67, 51.07 and 56.26 µg/mL against MCF-7, HeLa and HepG2 cancer cell lines, respectively, which confirms its potent anticancer action. The biocompatibility of green synthesized AgNPs is confirmed by their lack of cytotoxicity against normal human cells. The potent bioactivity exhibited by the green synthesized AgNPs leads towards the multiple use as antioxidant, antibacterial, anti-biofilm and cytotoxic agent.

Sustainable development through the bio-fabrication of ecofriendly ZnO nanoparticles and its approaches to toxicology and environmental protection

Mosquito control is becoming more difficult as a result of the rise in resistance to toxic chemical insecticides. The insecticides of bio-fabrication sources may serve as a convenient alternative to environmentally acceptable methods in the future. The larvicidal and pupicidal activities of bio-fabricated zinc oxide nanoparticles (ZnO NPs) on the different instar larvae and pupae of Anopheles subpictus Grassi (Malaria vector) and Culex quinquefasciatus Say (lymphatic filariasis) were investigated in this study. The results recorded from XRD, FTIR, SEM-EDX, and TEM analyses confirmed the bio-fabrication of ZnO NPs. Such nanoparticles were nearly spherical and agglomerated with a size of 34.21 nm. GC-MS analysis of methanol extract revealed the compound, stigmasterol (C29H48O) as major one. Mosquito larvae and pupae of targeted mosquito were tested against varied concentrations of the bio-fabricated ZnO NPs and methanol extract of Vitex negundo for 24 h. The maximum activity was recorded from ZnO NPs against the larvae and pupae of A. subpictus LC50 which were 1.70 (I), 1.66 (II), 1.93 (III), 2.48 (IV), and 3.63 mg/L (pupa) and C. quinquefasciatus LC50 were 1.95 (I), 2.63 (II), 2.90 (III), 4.32 (IV), and 4.61 mg/L (pupa) respectively. ZnO NPs exhibited strong DPPH radical and FRAP scavengers compared to the aqueous extract of V. negundo. Also, V. negundo leaf methanol extract (VNLME) and ZnO NPs were evaluated for their cytotoxicity on HeLa cells, which exhibited the IC50 values of 72.35 and 43.70μg/mL, respectively. The methylene blue (MB) dye, which is harmful to both aquatic and terrestrial life, was degraded using the biosynthesized ZnO nanoparticles. At 664 nm, 81.2% of the MB dye had degraded after 120 min of exposure to sunlight. Overall, our results revealed that ZnO NPs are the perfect biological agent and economical for the control of malaria, filariasis vectors, antioxidant, HeLa cells, and MB blue dye degradation under sunlight irradiation.

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Toxicity of plant-based silver nanoparticles to vectors and intermediate hosts: Historical review and trends

Green nanoparticles (GNPs), mainly green silver nanoparticles (Ag NPs), have been recommended as sustainable and eco-friendly technologies to control vectors and intermediate hosts. The aim of the current study is to carry out a historical and systematic literature review about the use of green plant-based Ag NPs (GP-Ag NPs) to control medically important mosquito, tick and gastropods. Data about the number of studies published per year, geographical distribution of studies (mailing address of the corresponding author), synthesis type (plant species, plant structure and extract types), physicochemical properties of GP-Ag NPs, experimental designs, developmental stages and the toxic effects on mosquitoes, ticks and gastropods were summarized and discussed. Revised data showed that GP-Ag NPs synthesis and toxicity in mosquitoes, ticks and snails depend on plant species, plant part, extract types, exposure condition and on the analyzed species. GP-Ag NPs induced mortality, tissue damage, biochemical and behavioral changes in mosquitoes and reduced their fecundity, oviposition, egg hatching and longevity. Ticks exposed to GP-Ag NPs presented increased mortality and reduced oviposition, while on snails, studies demonstrated mortality, oxidative stress, and DNA damage. Immune responses were also observed in snails after their exposure to GP-Ag NPs. GP-Ag NPs reduced the reproduction and population of several vectors and intermediate hosts. This finding confirms their potential to be used in gastropod control programs. Future studies about current gaps in knowledge are recommended.

Biosynthesis of silver capped magnesium oxide nanocomposite using Olea cuspidata leaf extract and their photocatalytic, antioxidant and antibacterial activity

Green chemistry is a modern area of research which covers synthesis of nanomaterials through useful, environmentally, economically friendly techniques and their use in different fields. The synthesis involves the formation of bimetallic nanomaterials to enhance their synergistic relationship and achieve special modulated properties. That's why bimetallic nanomaterials are extremely important and gaining interest among researchers in the field of medicinal chemistry for the treatment of various diseases. In this particular study, bimetallic nanoparticles synthesis was done by reduction procedure using leaf extract of Olea cuspidata. The phytochemicals in leaf extract act as stabilizing and capping agent in reduction of precursor's salts. The characterization of green synthesized Ag@MgO nanocomposite was done through several analytical techniques such as ultraviolet-visible (UV-vis) spectroscopy, X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), Scanning electron microscope (SEM), High resolution transmission electron microscope (HRTEM) and Zeta potential. To explore the biological potential of synthesized nanocomposite, antibacterial activities against gram negative (Escherichia coli) bacteria and gram positive (Staphylococcus aureus) has been evaluated. The photocatalytic activity in contrary to methylene blue (MB) decomposition was seen efficiently. Moreover, the antioxidant nature of green synthesized Ag@MgO nanocomposite was analyzed by destabilizing and scavenging maximum percentage (93 %) of dangerous and harmful 2, 2-diphenyl-1-picrylhydrazyl (DPPH) free radical. The best and surprising results provided the information for the presence of essential and vital components in Olea Cuspidata in the form of organic acids (Citrus Acid) aids in stabilizing the entire structure with enhanced properties. Up to the best of our knowledge, the facts and results obtained regarding the structure of Ag@MgO nanocomposite clearly illustrates the uniqueness of green chemistry and also its role in future developing multifunctional nanoparticles in the field of nanobiotechnology.

Plant extracts for developing mosquito larvicides: From laboratory to the field, with insights on the modes of action

In the last decades, major research efforts have been done to investigate the insecticidal activity of plant-based products against mosquitoes. This is a modern and timely challenge in parasitology, aimed to reduce the frequent overuse of synthetic pesticides boosting resistance development in mosquitoes and causing serious threats to human health and environment. This review covers the huge amount of literature available on plant extracts tested as mosquito larvicides, particularly aqueous and alcoholic ones, due to their easy formulation in water without using surfactants. We analysed results obtained on more than 400 plant species, outlining that 29 of them have outstanding larvicidal activity (i.e., LC₅₀ values below 10 ppm) against major vectors belonging to the genera Anopheles, Aedes and Culex, among others. Furthermore, synergistic and antagonistic effects between plant extracts and conventional pesticides, as well as among selected plant extracts are discussed. The efficacy of pure compounds isolated from the most effective plant extracts and - when available - their mechanism of action, as well as the impact on non-target species, is also covered. These belong to the following class of secondary metabolites: alkaloids, alkamides, sesquiterpenes, triterpenes, sterols, flavonoids, coumarins, anthraquinones, xanthones, acetogenonins and aliphatics. Their mode of action on mosquito larvae ranges from neurotoxic effects to inhibition of detoxificant enzymes and larval development and/or midugut damages. In the final section, current drawbacks as well as key challenges for future research, including technologies to synergize efficacy and improve stability - thus field performances - of the selected plant extracts, are outlined. Unfortunately, despite the huge amount of laboratory evidences about their efficacy, only a limited number of studies was aimed to validate their efficacy in the field, nor the epidemiological impact potentially arising from these vector control operations has been assessed. This strongly limits the development of commercial mosquito larvicides of botanical origin, at variance with plant-borne products developed in the latest decades to kill or repel other key arthropod species of medical and veterinary importance (e.g., ticks and lice), as well as mosquito adults. Further research on these issues is urgently needed.

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.

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.

Size-controlled fabrication of silver nanoparticles using the Hedyotis puberula leaf extract: toxicity on mosquito vectors and impact on biological control agents

As a low-cost and eco-friendly control tool, Ag nanoparticles were fabricated usingHedyotis puberulaaqueous extract as a reducing and capping agent and showed potent activity against malaria and arbovirus vectors with low biotoxicity against non-target aquatic organisms.