Anti-larvicidal Activity of Silver Nanoparticles Synthesized from Sargassum polycystum Against Mosquito Vectors

Use of micro and macroalgae extracts for the control of vector mosquitoes

Mosquitoes are one of the most dangerous vectors of human diseases such as malaria, dengue, chikungunya, and Zika virus. Controlling these vectors is a challenging responsibility for public health authorities worldwide. In recent years, the use of products derived from living organisms has emerged as a promising approach for mosquito control. Among these living organisms, algae are of great interest due to their larvicidal properties. Some algal species provide nutritious food for larvae, while others produce allelochemicals that are toxic to mosquito larvae. In this article, we reviewed the existing literature on the larvicidal potential of extracts of micro- and macroalgae, transgenic microalgae, and nanoparticles of algae on mosquitoes and their underlying mechanisms. The results of many publications show that the toxic effects of micro- and macroalgae on mosquitoes vary according to the type of extraction, solvents, mosquito species, exposure time, larval stage, and algal components. A few studies suggest that the components of algae that have toxic effects on mosquitoes show through synergistic interaction between components, inhibition of feeding, damage to gut membrane cells, and inhibition of digestive and detoxification enzymes. In conclusion, algae extracts, transgenic microalgae, and nanoparticles of algae have shown significant larvicidal activity against mosquitoes, making them potential candidates for the development of new mosquito control products.

Enterobacter hormaechei-Driven Novel Biosynthesis of Tin Oxide Nanoparticles and Evaluation of Their Anti-aging, Cytotoxic, and Enzyme Inhibition Potential

Nanotechnology is a research hotspot that has gained considerable interest due to its potential inferences in the bioscience, medical, and engineering disciplines. The present study uses biomass from the Enterobacter hormaechei EAF63 strain to create bio-inspired metallic tin oxide nanoparticles (SnO2 NPs). The biosynthesized NPs were extensively analyzed using UV spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and Fourier transform infrared (FTIR) techniques. The identification of the crystalline phase was confirmed by XRD. The SEM technique elucidated the morphological characteristics and size of SnO2 NPs. SEM investigation revealed that the SnO2 NPs have a size of 10 nm with spherical morphology. The capping of NPs was confirmed by FTIR analysis that revealed the presence of different compounds found in the biomass of the E. hormaechei EAF63 strain. Later, EDX confirmed the elemental composition of NPs. Moreover, the synthesized SnO2 NPs were employed for important applications including anti-aging, anti-Alzheimer's, anti-inflammatory, anti-larvicidal, and antibacterial action against sinusitis pathogens. The highest value was observed for Streptococcus pyogenes (19.75 ± 0.46), followed by Moraxella catarrhalis (17.49 ± 0.82) and Haemophilus influenzae (15.31 ± 0.73), respectively. Among the used concentrations, the highest inhibition of 76.8 ± 0.93 for 15-lipoxygenase (15-LOX) was observed at 400 μg/mL, followed by 67.4 ± 0.91 for cyclooxygenase-1 (COX-1). So, as an outcome, E. hormaechei-mediated SnO2 NPs might be considered as the safe and effective nanoplatforms for multifunctional biological applications in the field of nanomedicine.

A critical review on the bio-mediated green synthesis and multiple applications of magnesium oxide nanoparticles

Nowadays, advancements in nanotechnology have efficiently solved many global problems, such as environmental pollution, climate change, and infectious diseases. Nano-scaled materials have played a central role in this evolution. Chemical synthesis of nanomaterials, however, required hazardous chemicals, unsafe, eco-unfriendly, and cost-ineffective, calling for green synthesis methods. Here, we review the green synthesis of MgO nanoparticles and their applications in biochemical, environmental remediation, catalysis, and energy production. Green MgO nanoparticles can be safely produced using biomolecules extracted from plants, fungus, bacteria, algae, and lichens. They exhibited fascinating and unique properties in morphology, surface area, particle size, and stabilization. Green MgO nanoparticles served as excellent antimicrobial agents, adsorbents, colorimetric sensors, and had enormous potential in biomedical therapies against cancers, oxidants, diseases, and the sensing detection of dopamine. In addition, green MgO nanoparticles are of great interests in plant pathogens, phytoremediation, plant cell and organ culture, and seed germination in the agricultural sector. This review also highlighted recent advances in using green MgO nanoparticles as nanocatalysts, nano-fertilizers, and nano-pesticides. Thanks to many emerging applications, green MgO nanoparticles can become a promising platform for future studies.

Biologically Synthesized Silver Nanoparticles and Their Diverse Applications

Nanotechnology has become the most effective and rapidly developing field in the area of material science, and silver nanoparticles (AgNPs) are of leading interest because of their smaller size, larger surface area, and multiple applications. The use of plant sources as reducing agents in the fabrication of silver nanoparticles is most attractive due to the cheaper and less time-consuming process for synthesis. Furthermore, the tremendous attention of AgNPs in scientific fields is due to their multiple biomedical applications such as antibacterial, anticancer, and anti-inflammatory activities, and they could be used for clean environment applications. In this review, we briefly describe the types of nanoparticle syntheses and various applications of AgNPs, including antibacterial, anticancer, and larvicidal applications and photocatalytic dye degradation. It will be helpful to the extent of a better understanding of the studies of biological synthesis of AgNPs and their multiple uses.

Sargassum myriocystum-mediated TiO2-nanoparticles and their antimicrobial, larvicidal activities and enhanced photocatalytic degradation of various dyes

Recently, the phyco-synthesis of nanoparticles has been applied as a reliable approach to modern research field, and it has yielded a wide spectrum of diverse uses in fields such as biological science and environmental science. This study used marine natural resource seaweed Sargassum myriocystum due to their unique phytochemicals and their significant attributes in giving effective response on various biomedical applications. The response is created by their stress-tolerant environmental adaptations. This inspired us to make an attempt using the above-mentioned charactersitics. Therfore, the current study performed phycosynthesis of titanium dioxide nanoparticles (TiO2-NPs) utilising aqueous extracts of S. myriocystum. The TiO2-NPs formation was confirmed in earlier UV-visible spectroscopy analysis. The crystalline structure, functional groups (phycomolecules), particle morphology (cubic, square, and spherical), size (∼50-90 nm), and surface charge (negative) of the TiO2-NPs were analysed and confirmed by various characterisation analyses. In addition, the seaweed-mediated TiO2-NPs was investigated, which showed potential impacts on antibacterial activity and anti-biofilm actions against pathogens (Staphylococcus aureus, S. epidermidis, Escherichia coli, Proteus vulgaris, Pseudomonas aeruginosa, and Klebsiella pneumoniae). Additionally, some evaluations were performed on larvicidal activities of TiO2-NPs in oppose to Aedes aegypti and Culex quinquefasciatus mosquitos and the environmental effects of photocatalytic activities against methylene blue and crystal violet under sunlight irradiation. The highest percent of methylene blue degradation was observed at 92.92% within 45 min. Overall, our findings suggested that S. myriocystum mediates TiO2-NPs to be a potent disruptive material for bacterial pathogens and mosquito larvae and also to enhance the photocatalytic dye degradation.

Screening and evaluation of different algal extracts and prospects for controlling the disease vector mosquito Culex pipiens L

Continual application of synthetic insecticides in controlling mosquito larvae has resulted in several problems as build-up of mosquito resistance beside to negative impacts on human health and environment. Discovering new and affordable bio-insecticidal agents with high efficiency, cost effective and target specific become a crucial need. The current study assessed the larvicidal activity of eight methanolic algal extracts belong to three different algal divisions against the 3^rd larval instar of Culex pipiens L. (Diptera: Culicidae). Comparative studies showed that four species of red and green algal extracts exhibited good larvicidal activity. Galaxaura elongata and Jania rubens (Rhodophyta), Codium tomentosum and Ulva intestinales (Chlorophyta) showed higher larvicidal potencies than Padina boryana, Dictyota dichotoma, and Sargassum dentifolium (Phaeophyta) and Gelidium latifolium (Rhodophyta). The maximum level of toxicity was achieved by exposure to G. elongata extract with LC₅₀ (31.13 ppm), followed by C. tomentosum (69.85 ppm) then J. rubens (84.82 ppm) and U. intestinalis (97.54 ppm), while the lowest toxicity exhibited by G. latifolium (297.38 ppm) at 72 h post- treatment. The application of LC₅₀ values of G. elongate, J. rubens, C. tomentosum, and U. intestinalis extracts affected the activities of antioxidant enzymes viz. superoxide dismutase, catalase and glutathione peroxidase as oxidative stress markers. An increase of antioxidant enzymes activities was recorded. Therefore, a significant elimination of free radicals, causing toxic effects. Overall, this study casts light on the insecticidal activity of some algal extracts, suggesting the possibility of application of these bio- agents as novel and cost- effective larvicides.

Elucidation of larvicidal potential of metallic and environment friendly food-grade nanostructures against Aedes albopictus

To combat health challenges associated with mosquito-borne diseases, the larvicidal activity of metallic nanoparticles, food-grade polymeric nano-capsules and insecticides was investigated against larvae of Aedes albopictus as an effective alternate control approach. The Ae. albopictus was identified using sequencing and phylogenetic analyses of COXI, CYTB and ITS2 genes. The characterization of synthesized nanostructures was performed through Zetasizer, UV-VIS spectroscopy, atomic force microscopy, scanning electron microscopy and energy dispersive X-ray spectroscopy. The mosquito larvae were exposed to varying concentration of nanostructures and insecticides, and their percentage mortality was evaluated at different time intervals of 24 h and 48 h exposure. The highest efficacy was observed in zinc oxide nanoparticles (ZnO-NPs) and polymeric nanocapsules FG-Cur E-III (LC50 = 0.24 mg/L, LC90 = 0.6 mg/L) and (LC50 = 3.8 mg/L, LC90 = 9.33 mg/L), respectively, after 24 h; while (LC50 = 0.18 mg/L, LC90 = 0.43 mg/L) and (LC50 = 1.95 mg/L, LC90 = 6.46 mg/L), respectively, after 48 h against fourth instar larvae of Ae. albopictus. Ag, CuO, NiTiO3 and CoTiO3 nanoparticles evaluated in this study also showed promising larvicidal activity. Although ZnO-NPs proved to be effective larvicides, their possible toxicity (producing ROS species) can limit their use. The curcumin nanostructures (FG-Cur E-III) stabilized by food-grade materials are thought to exert their larvicidal activity by binding to sterol carrier protein-2, and depriving the larvae from the essential dietary cholesterol, and bears effective larvicidal potential as safe alternative for chemical larvicides, due to their environment friendly, food-grade and easy biodegradability.

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.

Synthesis of Silver Nanoparticles and their Biomedical Applications - A Comprehensive Review

Generally, silver is considered as a noble metal used for treating burn wound infections, open wounds and cuts. However, the emerging nanotechnology has made a remarkable impact by converting metallic silver into silver nanoparticles (AgNPs) for better applications. The advancement in technology has improved the synthesis of NPs using biological method instead of physical and chemical methods. Nonetheless, synthesizing AgNPs using biological sources is ecofriendly and cost effective. Till date, AgNPs are widely used as antibacterial agents; therefore, a novel idea is needed for the successful use of AgNPs as therapeutic agents to uncertain diseases and infections. In biomedicine, AgNPs possess significant advantages due to their physical and chemical versatility. Indeed, the toxicity concerns regarding AgNPs have created the need for non-toxic and ecofriendly approaches to produce AgNPs. The applications of AgNPs in nanogels, nanosolutions, silver based dressings and coating over medical devices are under progress. Still, an improvised version of AgNPs for extended applications in an ecofriendly manner is the need of the hour. Therefore, the present review emphasizes the synthesis methods, modes of action under dissipative conditions and the various biomedical applications of AgNPs in detail.

Synthesis of magnetite-based nanocomposites for effective removal of brilliant green dye from wastewater

The present study aims at evaluating the batch scale potential of cotton shell powder (CSP), Moringa oleifera leaves (ML), and magnetite-assisted composites of Moringa oleifera leaves (MLMC) and cotton shell powder (CSPMC) for the removal of brilliant green dye (BG) from synthetic wastewater. This is the first attempt to combine biosorbents with nanoparticles (NPs) for the removal of BG. The surface properties of ML, CSP, and their composites were characterized with Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and energy-dispersive X-ray (EDX). The impact of dosage of the adsorbents (1-4 g/L), initial concentrations of BG (20-320 mg/L), pH (6-12), and contact time (15-180 min) on BG removal was evaluated. The BG removal was in order of CSPMC > MLMC > CSP > ML (98.8-86.6% > 98.2-82.0% > 92.3-70.7% > 89.0-57.4%) at optimum dosage (2 g/L) and pH (8). Moreover, maximum adsorption (252.17 mg/g) was obtained with CSPMC. The experimental results showed better fit with Freundlich adsorption isotherm model and kinetic data revealed that sorption followed pseudo-second-order kinetic model. The values of Gibbs free energy and mean free energy of sorption showed that physical adsorption was involved in the removal of BG. FTIR results confirmed that -O-H, -C-OH, =C-H, -C-H, =-CH₃, HC ≡ CH, C=C, -C=O, -C-N, and -C-O-C- groups were involved in the removal of BG. The results revealed that application of low-cost biosorbents combined with NPs is very effective and promising for the removal of textile dyes from wastewater.