An improved insecticidal activity of silver nanoparticle synthesized by using Sargassum muticum

Bioactive nanoparticles derived from marine brown seaweeds and their biological applications: a review

The biosynthesis of novel nanoparticles with varied morphologies, which has good implications for their biological capabilities, has attracted increasing attention in the field of nanotechnology. Bioactive compounds present in the extract of fungi, bacteria, plants and algae are responsible for nanoparticle synthesis. In comparison to other biological resources, brown seaweeds can also be useful to convert metal ions to metal nanoparticles because of the presence of richer bioactive chemicals. Carbohydrates, proteins, polysaccharides, vitamins, enzymes, pigments, and secondary metabolites in brown seaweeds act as natural reducing, capping, and stabilizing agents in the nanoparticle's synthesis. There are around 2000 species of seaweed that dominate marine resources, but only a few have been reported for nanoparticle synthesis. The presence of bioactive chemicals in the biosynthesized metal nanoparticles confers biological activity. The biosynthesized metal and non-metal nanoparticles from brown seaweeds possess different biological activities because of their different physiochemical properties. Compared with terrestrial resources, marine resources are not much explored for nanoparticle synthesis. To confirm their morphology, characterization methods are used, such as absorption spectrophotometer, X-ray diffraction, Fourier transforms infrared spectroscopy, scanning electron microscope, and transmission electron microscopy. This review attempts to include the vital role of brown seaweed in the synthesis of metal and non-metal nanoparticles, as well as the method of synthesis and biological applications such as anticancer, antibacterial, antioxidant, anti-diabetic, and other functions.

Anabaena sp. A-1 mediated molybdenum oxide nanoparticles: A novel frontier in green synthesis, characterization and pharmaceutical properties

Green-synthesized metal oxide nanoparticles have garnered considerable attention due to their simple, sustainable, and eco-friendly attributes, coupled with their diverse applications in biomedicine and environmental context. The current study shows a sustainable approach for synthesizing molybdenum oxide nanoparticles (MoONPs) utilizing an extract from Anabaena sp. A-1. This novel approach marks a significant milestone as various spectral approaches were employed for characterization of the green-synthesized MoONPs. Ultraviolet-visible (UV-Vis) spectroscopic analysis revealed a surface plasmon resonance (SPR) peak of MoONPs at 538 nm. Fourier transform infrared (FTIR) spectral analysis facilitated the identification of functional groups responsible for both the stability and production of MoONPs. Scanning electron microscopy (SEM) was utilized revealing a rod shape morphology of the MoONPs. X-ray diffraction (XRD) analysis yielded a calculated crystal size of 31 nm, indicating the crystalline nature of MoONPs. Subsequently, biological assays were employed to ascertain the potential of the bioengineered MoONPs. The 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay was used to quantify free radical scavenging activity, revealing an antioxidant capacity of 68.1% at 200 μg/mL. To evaluate antibacterial and antifungal efficacy, the disc diffusion method was employed across varying concentrations of MoONPs (6.25, 12.5, 25, 50, 100, 150, 200 μg/mL). Quantification of cytotoxicity was performed via a brine shrimp assay, yielding an IC50 value of 552.3 μg/mL, a metric of moderate cytotoxicity. To assess the biocompatibility of MoONPs, an antihemolytic assay was conducted, confirming their safety profile. Additionally, MoONPs exhibited non-toxic attributes in an insecticidal assay. Notably, in anti-inflammatory assay MoONPs showed an inactive nature towards the reactive oxygen species. In conclusion, these findings highlight the potential versatility of MoONPs in various biological applications, extending beyond their recognized anti-inflammatory and insecticidal properties. RESEARCH HIGHLIGHTS: This study marks an advancement in nanotechnology, exploring ways for MoONPs fabrication, representing a unique and unexplored research domain. Green-synthesized MoONPs using Anabaena sp. A-1 extract offers a sustainable and eco-friendly approach. Characterized by UV-Vis, FTIR, SEM, and XRD, MoONPs demonstrate rod-shaped morphology and crystalline nature. Bioengineered MoONPs exhibit versatility in biological applications, demonstrating notable antioxidant, antibacterial and antifungal efficacy, moderate cytotoxicity, biocompatibility, and insecticidal properties, emphasizing their multifaceted utility. The research findings highlight the potential utilization of MoONPs across a spectrum of biological applications, thereby suggesting their promising role in the realm of biomedicine and environmental context.

Marine Natural Products: The Important Resource of Biological Insecticide

Due to the unique environmental conditions and vast territory, marine habitat breeds more abundant biological resources than terrestrial environment. Massive marine biological species provide valuable resources for obtaining a large number of natural products with diverse structure and excellent activity. In recent years, new breakthroughs have been made in the application of marine natural products in drug development. In addition, the use of marine natural products to develop insecticides and other pesticide products has also been widely concerned. Targeting marine plants, animals, and microorganisms, we have collected information on marine natural products with insecticidal activity for nearly decade, including alkaloids, terpenes, flavonoids and phenols fatty acids, peptides, and proteins, et al. In addition, some active crude extracts are also included. This review describes the insecticidal activities of marine natural products and their broad applications for future research in agriculture and health.

Silver Nanoparticle Production by Ruta graveolens and Testing Its Safety, Bioactivity, Immune Modulation, Anticancer, and Insecticidal Potentials

Ruta graveolens, a plant belonging to the family Rutaceae, is traditionally used as a medicinal plant and a flavoring agent in food. This work aimed to prepare silver nanoparticles (AgNPs) using the ethanol extract from R. graveolens leaves and test different biological activities as well as insecticidal potentials in the extract and extract prepared AgNPs. Dried and powdered R. graveolens leaves were subjected to extraction using ethanol, and this extract was used to synthesize AgNPs. AgNP synthesis was monitored by the change in color, UV spectrophotometry, and electron microscopy (scanning). Fourier transform infrared (FT-IR) spectroscopy was used to monitor the functional groups in the extracts. Immunological, physiological, anticancer, antibacterial, and insecticidal potentials of the extract and its prepared AgNPs were tested. Results showed the ability of the leaf extract to synthesize. SEM examination revealed a spherical shape of AgNPs with a size of 40-45 nm. The extract contained many functional groups as indicated by FT-IR. The extract alone inhibited the growth of normal rat splenic cells, while the extract containing AgNPs stimulated its growth. Extract alone stimulated HeLa cell proliferation and inhibited HepG2 growth, while both cell line growth was inhibited by the extract containing AgNPs. Both the extract and extract with AgNPs were safe on RBCs and did not cause any severe elevation in liver enzymes. The extract alone and with AgNPs showed insecticidal activity against Culex pipiens. Our findings suggest that the R. graveolens leaf extract, alone or with AgNPs, is biologically safe on animal cells and has antibacterial, insecticidal, and immunomodulation potentials.

Study of anticancer, antimicrobial, immunomodulatory, and silver nanoparticles production by Sidr honey from three different sources

Sidr honey is used as food and medicine in many countries. Study of immunomodulatory and anticancer activity of Sidr honey did not tested before. The aim of this work was to study the anticancer activity and immunomodulatory as well as antimicrobial potential of Sidr honey and its synthesized silver nanoparticles (AgNPs). Sidr honey from three sources (two from Kingdom of Saudi Arabia (KSA) and one from Pakistan) was diluted to 20% and tested for its biological activities and to synthesize AgNPs. The results demonstrated that honeys could produce AgNPs (spherical shape), modulated the growth of normal splenic cells, and have antimicrobial activities. Sidr honey has anticancer activity against HepG2 but not Hela cells. Sidr honey can be used as antimicrobial agent, but can be used as anticancer agent with care as it stimulated cell growth of some lines (e.g., Hala) and inhibited another (e.g., HepG2).

Green preparation of seaweed-based silver nano-liquid for cotton pathogenic fungi management

Silver nanoparticles (Ag NPs) were synthesised using the crude ethyl acetate extracts of Ulva lactuca and evaluated their bioefficacy against two crop-damaging pathogens. The sets of lattice planes in the XRD spectrum for the Ag NPs were indexed to the 111, 200, 220 and 311 orientations and support the crystalline nature of the Ag NPs. The 3414 and 2968 cm^-1 peaks were observed in crude algal thallus extract and they were characteristic of terpenoids. Further, a peak at 1389 cm^-1 was observed as fatty acids. The marine macroalgae terpenoids and palmitic acid acted as reducing agent and stabiliser, respectively. The size (3 and 50 nm) and shape (spherical) of Ag NPs were recorded. The energy-dispersive X-ray spectroscopy analysis exemplified the presence of silver in its elemental nature. Moreover, U. lactuca Ag NPs were effective against two cotton phytopathogens namely Fusarium oxysporum f.sp. vasinfectum (FOV) and Xanthomonas campestris pv. malvacearum (XAM). The minimum inhibitory concentration was found to be 80.0 and 43.33 μg ml^-1 against FOV and XAM, respectively. Results confirmed the anti-microbial activity of green nanoparticles against select pathogens and suggest their possible usage in developing antifungal agents for controlling destructive pathogens in a cotton agroecosystem.

Nanoformulations and their mode of action in insects: a review of biological interactions

While nanoparticles (NPs) can be used as insecticides by themselves, they can also be carriers for insecticidal chemicals. Existing literature suggests that the smaller the NP size, the greater the toxicity and penetration into the insect's body. Nonetheless, there is a lack of literature pertaining to the mode of action within insects. This review article summarizes the currently available entomological studies on the mechanisms of NP-insect interactions. Externally, NPs affect pigmentation and integrity of the cuticle, while internally they induce immune responses and alter gene expression leading to altered protein, lipid, and carbohydrate metabolism along with cellular toxicity that impairs development and reproduction of the insect. Consequently, insects are incapacitated due to the disruption of the nutrient intake, production of reactive oxygen species and altered biochemical activity while some NPs can promote growth and development as well as diminish the effects of nontarget toxicity.

Low Dose of Nanocapsules Containing Eucalyptus Oil Has Beneficial Repellent Effect Against Horn Fly (Diptera: Muscidae)

For the first time, the repellent and insecticidal effects of eucalypt essential oil (Eucalyptus globulus) in its free form and associated with different nanostructures (nanoemulsion and nanocapsules) were investigated against Musca domestica (Diptera: Muscidae) and Haemotobia irritans (Diptera: Muscidae) flies. Specimens of M. domestica were collected, separated into groups (n = 10), treated with aspersion of essential oil of eucalypt in its free (1, 5, and 10%) and nanostructured (nanoemulsion or nanoencapsulated at 1, 3, and 5%, respectively) forms. The determination of the insecticidal effect was performed by counting the number of dead flies at intervals of 30, 60, 120, 360 and 750 min after oil aspersion. E. globulus essential oil showed insecticidal effect against M. domestica at concentrations of 1 and 5%. Eucalypt essential oil (10%) caused 100% mortality of M. domestica after 750 min of the treatment. Nanocapsules (3 and 5%) showed efficacy by reducing the number of flies. On the other hand, nanoemulsion did not show insecticidal effect. The repellent action of E. globulus concentrations of 5% was tested against H. irritans on naturally infested cows. The repellent action against H. irritans was verified soon after pulverization. After 24 h, a significant reduction on horn flies' population (83.33 and 66.66%) was observed using free and nanoencapsulated forms tested, respectively. E. globulus essential oil demonstrated insecticidal and repellent effects against M. domestica and H. irritans flies.

DIETARY SILVER NANOPARTICLES REDUCE FITNESS IN A BENEFICIAL, BUT NOT PEST, INSECT SPECIES

Silver nanoparticles (AgNPs) have antimicrobial and insecticidal properties and they have been considered for their potential use as insecticides. While they do, indeed, kill some insects, two broader issues have not been considered in a critical way. First, reports of insect-lethal AgNPs are often based on simplistic methods that yield nanoparticles of nonuniform shapes and sizes, leaving questions about the precise treatments test insects experienced. Second, we do not know how AgNPs influence beneficial insects. This work addresses these issues. We assessed the influence of AgNPs on life history parameters of two agricultural pest insect species, Heliothis virescens (tobacco budworm) and Trichoplusia ni (cabbage looper) and a beneficial predatory insect species, Podisus maculiventris (spined soldier bug), all of which act in agroecosystems. Rearing the two pest species on standard media amended with AgNPs led to negligible influence on developmental times, pupal weights, and adult emergence, however, they led to retarded development, reductions in adult weight and fecundity, and increased mortality in the predator. These negative effects on the beneficial species, if also true for other beneficial insect species, would have substantial negative implications for continued development of AgNPs for insect pest management programs.

Fighting arboviral diseases: low toxicity on mammalian cells, dengue growth inhibition (in vitro), and mosquitocidal activity of Centroceras clavulatum-synthesized silver nanoparticles

Dengue is a mosquito-borne viral disease that has rapidly spread in all regions of the world in recent years. Female mosquitoes, mainly Aedes aegypti, transmit dengue. Approximately 3,900 million people, in 128 countries, are at risk of dengue infection. Recently, a focus has been provided on the potential of green-synthesized nanoparticles as inhibitors of the production of dengue viral envelope (E) protein in Vero cells and downregulators of the expression of dengue viral E gene. Algae are an outstanding reservoir of novel compounds, which may help in the fight against mosquito-borne diseases. In this research, silver nanoparticles (AgNP) were rapidly synthesized using a cheap extract of the alga Centroceras clavulatum. AgNP were characterized by UV–vis spectrophotometry, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and X-ray diffraction (XRD). In mosquitocidal assays, LC50 values of C. clavulatum extract against A. aegypti larvae and pupae were 269.361 ppm (larva I), 309.698 ppm (larva II), 348.325 ppm (larva III), 387.637 ppm (larva IV), and 446.262 ppm (pupa). C. clavulatum extract also exhibited moderate antioxidant activity, both in 2,2-diphenyl-1-picrylhydrazyl (DPPH) and nitric oxide (NO) radical scavenging assays. LC50 values of C. clavulatum-synthesized AgNP were 21.460 ppm (larva I), 23.579 ppm (larva II), 25.912 ppm (larva III), 29.155 ppm (larva IV), and 33.877 ppm (pupa). Furthermore, C. clavulatum-synthesized AgNP inhibited dengue (serotype dengue virus type-2 (DEN-2)) viral replication in Vero cells. Notably, 50 μg/ml of green-synthesized AgNP showed no cytotoxicity on Vero cells while reduced DEN-2 viral growth of more than 80%; 12.5 μg/ml inhibited viral growth of more than 50%. Cellular internalization assays highlighted that untreated infected cells showed high intensity of fluorescence emission, which denotes high level of viral internalization. Conversely, AgNP-treated infected cells showed reduced levels of fluorescence, failing to show significant viral load. Overall, our study showed that alga-mediated synthesis of metal nanoparticles may be considered to develop newer, safer, and cheap tools in the fight against the dengue virus, serotype DEN-2, and its vector A. aegypti, with little cytotoxicity on mammalian cells.

S argassum muticum-synthesized silver nanoparticles: an effective control tool against mosquito vectors and bacterial pathogens

Mosquito-borne diseases represent a deadly threat for millions of people worldwide. Furthermore, pathogens and parasites polluting water also constitute a severe plague for populations of developing countries. In this research, silver nanoparticles (AgNP) were synthesized using the aqueous extract of the seaweed Sargassum muticum. The production of AgNP was confirmed by surface plasmon resonance band illustrated in UV-vis spectrophotometry. AgNP were characterized by FTIR, SEM, EDX, and XRD analyses. AgNP were mostly spherical in shape, crystalline in nature, with face-centered cubic geometry, and mean size was 43-79 nm. Toxicity of AgNP was assessed against Aedes aegypti, Anopheles stephensi, and Culex quinquefasciatus. In laboratory, AgNP were highly toxic against larvae and pupae of the three mosquito species. Maximum efficacy was observed against A. stephensi larvae, with LC50 ranging from 16.156 ppm (larva I) to 28.881 ppm (pupa). In the field, a single treatment with AgNP (10 × LC50) in water storage reservoirs was effective against the three mosquito vectors, allowing complete elimination of larval populations after 72 h. In ovicidal experiments, egg hatchability was reduced by 100% after treatment with 30 ppm of AgNP. Ovideterrence assays highlighted that 10 ppm of AgNP reduced oviposition rates of more than 70% in A. aegypti, A. stephensi, and C. quinquefasciatus (OAI = -0.61, -0.63, and -0.58, respectively). Antibacterial properties of AgNP were evaluated against Bacillus subtilis, Klebsiella pneumoniae, and Salmonella typhi using the agar disk diffusion and minimum inhibitory concentration protocol. AgNP tested at 50 ppm evoked growth inhibition zones larger than 5 mm in all tested bacteria. Overall, the chance to use S. muticum-synthesized AgNP for control of mosquito vectors seems promising since they are effective at low doses and may constitute an advantageous alternative to build newer and safer mosquito control tools. This is the first report about ovicidal activity of metal nanoparticles against mosquito vectors.

Characterization and biotoxicity of Hypnea musciformis-synthesized silver nanoparticles as potential eco-friendly control tool against Aedes aegypti and Plutella xylostella

Two of the most important challenges facing humanity in the 21st century comprise food production and disease control. Eco-friendly control tools against mosquito vectors and agricultural pests are urgently needed. Insecticidal products of marine origin have a huge potential to control these pests. In this research, we reported a single-step method to synthesize silver nanoparticles (AgNP) using the aqueous leaf extract of the seaweed Hypnea musciformis, a cheap, nontoxic and eco-friendly material, that worked as reducing and stabilizing agent during the biosynthesis. The formation of AgNP was confirmed by surface plasmon resonance band illustrated in UV-vis spectrophotometer. AgNP were characterized by FTIR, SEM, EDX and XRD analyses. AgNP were mostly spherical in shape, crystalline in nature, with face-centered cubic geometry, and their mean size was 40-65nm. Low doses of H. musciformis aqueous extract and seaweed-synthesized AgNP showed larvicidal and pupicidal toxicity against the dengue vector Aedes aegypti and the cabbage pest Plutella xylostella. The LC50 value of AgNP ranged from 18.14 to 38.23ppm for 1st instar larvae (L1) and pupae of A. aegypti, and from 24.5 to 38.23ppm for L1 and pupae of P. xylostella. Both H. musciformis extract and AgNP strongly reduced longevity and fecundity of A. aegypti and P. xylostella adults. This study adds knowledge on the toxicity of seaweed borne insecticides and green-synthesized AgNP against arthropods of medical and agricultural importance, allowing us to propose the tested products as effective candidates to develop newer and cheap pest control tools.

Toxicity of seaweed-synthesized silver nanoparticles against the filariasis vector Culex quinquefasciatus and its impact on predation efficiency of the cyclopoid crustacean Mesocyclops longisetus

Nearly 1.4 billion people in 73 countries worldwide are threatened by lymphatic filariasis, a parasitic infection that leads to a disease commonly known as elephantiasis. Filariasis is vectored by mosquitoes, with special reference to the genus Culex. The main control tool against mosquito larvae is represented by treatments with organophosphates and insect growth regulators, with negative effects on human health and the environment. Recently, green-synthesized nanoparticles have been proposed as highly effective larvicidals against mosquito vectors. In this research, we attempted a reply to the following question: do green-synthesized nanoparticles affect predation rates of copepods against mosquito larvae? We proposed a novel method of seaweed-mediated synthesis of silver nanoparticles using the frond extract of Caulerpa scalpelliformis. The toxicity of the seaweed extract and silver nanoparticles was assessed against the filarial vector Culex quinquefasciatus. Then, we evaluated the predatory efficiency of the cyclopoid crustacean Mesocyclops longisetus against larval instars of C. quinquefasciatus in a nanoparticle-contaminated water environment. Green-synthesized silver nanoparticles were characterized by UV-vis spectrum, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and X-ray diffraction (XRD). In mosquitocidal assays, the LC₅₀ values of the C. scalpelliformis extract against C. quinquefasciatus were 31.38 ppm (I), 46.49 ppm (II), 75.79 ppm (III), 102.26 ppm (IV), and 138.89 ppm (pupa), while LC₅₀ of silver nanoparticles were 3.08 ppm, (I), 3.49 ppm (II), 4.64 ppm (III), 5.86 ppm (IV), and 7.33 ppm (pupa). The predatory efficiency of the copepod M. longisetus in the control treatment was 78 and 59% against I and II instar larvae of C. quinquefasciatus. In a nanoparticle-contaminated environment, predation efficiency was 84 and 63%, respectively. Predation was higher against first instar larvae over other instars. Overall, our study showed that seaweed-synthesized silver nanoparticles can be proposed in synergy with biological control agents against Culex larvae, since their use leads to little detrimental effects against aquatic predators, such as copepods.