Green-synthesized silver nanoparticles as a novel control tool against dengue virus (DEN-2) and its primary vector Aedes aegypti

Eco-friendly synthesis of silver nanoparticles against mosquitoes: Pesticidal impact and indispensable biosafety assessment

The emergence of nanotechnology has opened new avenues for enhancing pest control strategies through the development of nanopesticides. Green-fabricated nanoparticles, while promising due to their eco-friendly synthesis methods, may still pose risks to biodiversity and ecosystem stability. The potential toxic effects of nanomaterials on ecosystems and human health raise important questions about their real-world application. Understanding the dose-response relationships of nanopesticides, both in terms of pest control efficacy and non-target organism safety, is crucial for ensuring their sustainable use in agricultural settings. This review delves into the complexities of silver nanopesticides, exploring their interactions with arthropod species, modes of action, and underlying mechanisms of toxicity. It discusses critical issues concerning the emergence of silver nanopesticides, spanning their mosquitocidal efficacy to environmental impact and safety considerations. While nano‑silver has shown promise in targeting insect pests, there is a lack of systematic research comparing its effects on different arthropod subclasses. Moreover, factors influencing nanotoxicity, such as nanoparticle size, charge, and surface chemistry, require further investigation to optimize the design of eco-safe nanoparticles for pest control. By elucidating the mechanisms by which nanoparticles interact with pests and non-target organisms, we can enhance the specificity and effectiveness of nanopesticides while minimizing unintended ecological consequences.

Plant-based synthesis, characterization approaches, applications and toxicity of silver nanoparticles: A comprehensive review

The development of an environmentally benign method for the synthesis of nanoparticles has been facilitated by green chemistry. "Green synthesis" uses a range of biological elements like microbes, plants, and other biodegradable materials to produce NPs. Active biomolecules that are secreted by natural strains and present in the plant extracts serve as both reducing and capping/stabilizing agents. Microorganisms' intracellular enzymes can reduce metal ions, which explains how NPs might potentially nucleate. Plant-based synthesis of nanomaterials is particularly promising owing to abundant resources, simplicity of synthesis, and low cost. Silver nanoparticles (AgNPs) are attracting great attention in the research community due to their wide variety of applications in chemistry, food technology, microbiology, and biomedicine. Recent years have seen a large amount of research on the bio-genic synthesis of AgNPs employing biomaterials like plant extract and bacteria as reducing agents. Herein we discuss a thorough overview of the plant-based synthesis of silver nanoparticles (AgNPs), characterization approaches, applications, and toxicity. The review covers the green chemistry and nanotechnology elements of producing AgNPs, including a thorough discussion of the plant extract mediated synthesis, detailed formation mechanism, and a well-balanced emphasis on hazards and advantages. Based on current developments, the optimisation strategies, applications, and interdisciplinary characteristics are also covered in detail.

Bioinspired and Green Synthesis of Silver Nanoparticles for Medical Applications: A Green Perspective

Silver nanoparticles (AgNPs) possess unmatched chemical, biological, and physical properties that make them unique compounds as antimicrobial, antifungal, antiviral, and anticancer agents. With the increasing drug resistance, AgNPs serve as promising entities for targeted drug therapy against several bacterial, fungal, and viral components. In addition, AgNPs also serve as successful anticancer agents against several cancers, including breast, prostate, and lung cancers. Several works in recent years have been done towards the development of AgNPs by using plant extracts like flowers, leaves, bark, root, stem, and whole plant parts. The green method of AgNP synthesis thus has several advantages over chemical and physical methods, especially the low cost of synthesis, no toxic byproducts, eco-friendly production pathways, can be easily regenerated, and the bio-reducing potential of plant derived nanoparticles. Furthermore, AgNPs are biocompatible and do not harm normally functioning human or host cells. This review provides an exhaustive overview and potential of green synthesized AgNPs that can be used as antimicrobial, antifungal, antiviral, and anticancer agents. After a brief introduction, we discussed the recent studies on the development of AgNPs from different plant extracts, including leaf parts, seeds, flowers, stems, bark, root, and whole plants. In the following section, we highlighted the different therapeutic actions of AgNPs against various bacteria, fungi, viruses, and cancers, including breast, prostate, and lung cancers. We then highlighted the general mechanism of action of AgNPs. The advantages of the green synthesis method over chemical and physical methods were then discussed in the article. Finally, we concluded the review by providing future perspectives on this promising field in nanotechnology.

Entomopathogenic fungi-based silver nanoparticles: a potential substitute of synthetic insecticides to counter behavioral and physiological immunity in Aedes aegypti mosquito (Diptera: Culicidae)

Excessive use of synthetic insecticides has resulted in environmental contamination and adverse effects on humans and other non-target organisms. Entomopathogenic fungi offer eco-friendly alternatives; however, their application for pest control requires significant advancement owing to limitations like slow killing time and effectiveness only when applied in higher amounts, whereas exposure to UV radiation, high temperature, and humidity can also reduce their viability and shelf-life. The nanoparticles synthesized using fungal extracellular extracts provide a new approach to use fungal pathogens. Our study focused on the synthesis of Metarhizium anisopliae-based silver nanoparticles (AgNPs) and evaluation of their efficiency on various physiological and behavioral parameters of the mosquito Aedes aegypti. The synthesis, size (27.6 d.nm, PDI = 0.209), zeta potential (- 24.3 mV), and shape of the AgNPs were determined through dynamic light scattering, scanning and transmission electron microscopic, and UV-visual spectroscopic analyses (432 nm). Our results showed significantly reduced survival (100% decrease in case of 3.2 and 1.8 μL/cm2 volumes, and 60% decrease in case of 0.8 μL/cm2 volume), phenoloxidase activity (t = 39.91; p = 0.0001), and gut microbiota, with increased oxidative stress and cell apoptosis in AgNPs-challenged mosquitoes. Furthermore, the AgNPs-exposed mosquitoes presented a concentration-specific decrease in flight locomotor activity (F = 17.312; p < 0.0001), whereas no significant changes in antifungal activity, self-grooming frequencies, or time spent were found. These findings enhance our understanding of mosquito responses to AgNPs exposure, and offer a more efficient mosquito control strategy using entomopathogenic fungi.

Anti-dengue potential and mosquitocidal effect of marine green algae-stabilized Mn-doped superparamagnetic iron oxide nanoparticles (Mn-SPIONs): an eco-friendly approach

Vector-borne diseases pose a significant public health challenge in economically disadvantaged nations. Malaria, dengue fever, chikungunya, Zika, yellow fever, Japanese encephalitis, and lymphatic filariasis are spread by mosquitoes. Consequently, the most effective method of preventing these diseases is to eliminate the mosquito population. Historically, the majority of control programs have depended on chemical pesticides, including organochlorines, organophosphates, carbamates, and pyrethroids. Synthetic insecticides used to eradicate pests have the potential to contaminate groundwater, surface water, beneficial soil organisms, and non-target species. Nanotechnology is an innovative technology that has the potential to be used in insect control with great precision. The goal of this study was to test the in vitro anti-dengue potential and mosquitocidal activity of Chaetomorpha aerea and C. aerea-synthesized Mn-doped superparamagnetic iron oxide nanoparticles (CA-Mn-SPIONs). The synthesis of CA-Mn-SPIONs using C. aerea extract was verified by the observable alteration in the colour of the reaction mixture, transitioning from a pale green colour to a brown. The study of UV-Vis spectra revealed absorbance peaks at approximately 290 nm, which can be attributed to the surface Plasmon resonance of the CA-Mn-SPIONs. The SEM, TEM, EDX, FTIR, vibrating sample magnetometry, and XRD analyses provided evidence that confirmed the presence of CA-Mn-SPIONs. In the present study, results revealed that C. aerea aqueous extract LC50 values against Ae. aegypti ranged from 222.942 (first instar larvae) to 349.877 ppm in bioassays (pupae). CA-Mn-SPIONs had LC50 ranging from 20.199 (first instar larvae) to 26.918 ppm (pupae). After treatment with 40 ppm CA-Mn-SPIONs and 500 ppm C. aerea extract in ovicidal tests, egg hatchability was lowered by 100%. Oviposition deterrence experiments showed that in Ae. aegypti, oviposition rates were lowered by more than 66% by 100 ppm of green algal extract and by more than 71% by 10 ppm of CA-Mn-SPIONs (oviposition activity index values were 0.50 and 0.55, respectively). Moreover, in vitro anti-dengue activity of CA-Mn-SPIONs has good anti-viral property against dengue viral cell lines. In addition, GC-MS analysis showed that 21 intriguing chemicals were discovered. Two significant phytoconstituents in the methanol extract of C. aerea include butanoic acid and palmitic acid. These two substances were examined using an in silico methodology against the NS5 methyltransferase protein and demonstrated good glide scores and binding affinities. Finally, we looked into the morphological damage and fluorescent emission of third instar Ae. aegypti larvae treated with CA-Mn-SPIONs. Fluorescent emission is consistent with ROS formation of CA-Mn-SPIONs against Ae. aegypti larvae. The present study determines that the key variables for the successful development of new insecticidal agents are rooted in the eco-compatibility and the provision of alternative tool for the pesticide manufacturing sector.

Promising applications of phyto-fabricated silver nanoparticles: Recent trends in biomedicine

The prospective contribution of phyto-nanotechnology to the synthesis of silver nanomaterials for biomedical purposes is attracting increasing interest across the world. Green synthesis of silver nanoparticles (Ag-NPs) through plants has been extensively examined recently, and it is now seen to be a green and efficient path for future exploitation and development of practical nano-factories. Fabrication of Ag-NPs is the process involves use of plant extracts/phyto-compounds (e.g.alkaloids, terpenoids, flavonoids, and phenolic compounds) to synthesise nanoparticles in more economical and feasible. Several findings concluded that in the field of medicine, Ag-NPs play a major role in pharmacotherapy (infection and cancer). Indeed, they exhibits novel properties but the reason is unclear (except some theoretical interpretation e.g. size, shape and morphology). But recent technological advancements help to address these questions by predicting the unique properties (composition and origin) by characterizing physical, chemical and biological properties. Due to increased list of publications and their application in the field of agriculture, industries and pharmaceuticals, issues relating to toxicity are unavoidable and question of debate. The present reviews aim to find out the role of plant extracts to synthesise Ag-NPs. It provides an overview of various phytocompounds and their role in the field of biomedicine (antibacterial, antioxidant, anticancer, anti-inflammatory etc.). In addition, this review also especially focused on various applications such as role in infection, oxidative stress, application in medical engineering, diagnosis and therapy, medical devices, orthopedics, wound healing and dressings. Additionally, the toxic effects of Ag-NPs in cell culture, tissue of different model organism, type of toxic reactions and regulation implemented to reduce associated risk are discussed critically. Addressing all above explanations, this review focus on the detailed properties of plant mediated Ag-NPs, its impact on biology, medicine and their commercial properties as well as toxicity.

Introduction of invasive mosquito species into Europe and prospects for arbovirus transmission and vector control in an era of globalization

BACKGROUND

Mosquito research in Europe has a long history, primarily focused on malaria vectors. In recent years, invasive mosquito species like the Asian tiger mosquito (Aedes albopictus) and the spread of arboviruses like dengue virus, chikungunya virus or bluetongue virus have led to an intensification of research and monitoring in Europe. The risk of further dissemination of exotic species and mosquito-borne pathogens is expected to increase with ongoing globalization, human mobility, transport geography, and climate warming. Researchers have conducted various studies to understand the ecology, biology, and effective control strategies of mosquitoes and associated pathogens.

MAIN BODY

Three invasive mosquito species are established in Europe: Asian tiger mosquito (Aedes albopictus), Japanese bush mosquito (Ae. japonicus), and Korean bush mosquito (Aedes koreicus). Ae. albopictus is the most invasive species and has been established in Europe since 1990. Over the past two decades, there has been an increasing number of outbreaks of infections by mosquito-borne viruses in particular chikungunya virus, dengue virus or Zika virus in Europe primary driven by Ae. albopictus. At the same time, climate change with rising temperatures results in increasing threat of invasive mosquito-borne viruses, in particular Usutu virus and West Nile virus transmitted by native Culex mosquito species. Effective mosquito control programs require a high level of community participation, going along with comprehensive information campaigns, to ensure source reduction and successful control. Control strategies for container breeding mosquitoes like Ae. albopictus or Culex species involve community participation, door-to-door control activities in private areas. Further measures can involve integration of sterile insect techniques, applying indigenous copepods, Wolbachia sp. bacteria, or genetically modified mosquitoes, which is very unlike to be practiced as standard method in the near future.

CONCLUSIONS

Climate change and globalization resulting in the increased establishment of invasive mosquitoes in particular of the Asian tiger mosquito Ae. albopictus in Europe within the last 30 years and increasing outbreaks of infections by mosquito-borne viruses warrants intensification of research and monitoring. Further, effective future mosquito control programs require increase in intense community and private participation, applying physical, chemical, biological, and genetical control activities.

From Benznidazole to New Drugs: Nanotechnology Contribution in Chagas Disease

Chagas disease is a neglected tropical disease caused by the protozoan Trypanosoma cruzi. Benznidazole and nifurtimox are the two approved drugs for their treatment, but both drugs present side effects and efficacy problems, especially in the chronic phase of this disease. Therefore, new molecules have been tested with promising results aiming for strategic targeting action against T. cruzi. Several studies involve in vitro screening, but a considerable number of in vivo studies describe drug bioavailability increment, drug stability, toxicity assessment, and mainly the efficacy of new drugs and formulations. In this context, new drug delivery systems, such as nanotechnology systems, have been developed for these purposes. Some nanocarriers are able to interact with the immune system of the vertebrate host, modulating the immune response to the elimination of pathogenic microorganisms. In this overview of nanotechnology-based delivery strategies for established and new antichagasic agents, different strategies, and limitations of a wide class of nanocarriers are explored, as new perspectives in the treatment and monitoring of Chagas disease.

Biosynthesizing Cassia fistula Extract-Mediated Silver Nanoparticles for MCF-7 Cell Lines Anti-Cancer Assay

The unique consequence of green synthesis is that the mediator plant is able to release chemicals that are efficacious as reducing as well as stabilizing agents. In this work, the fruit pulp and leaf essences of Cassia fistula have been used to manufacture silver nanoparticles through the green synthesis technique. The sculpturing of nanoparticles was accomplished by utilizing the reduction phenomenon that ensued due to the reaction between plant essences and the precursor solution. These biosynthesized silver nanoparticles were examined, where we used scanning electron microscopy, UV-vis spectroscopy, and X-ray diffraction techniques as means to analyze the structure, optical properties, and crystalline behavior, respectively. The absorption spectra for fruit and leaf extracts obtained from the UV-vis analyses peaked at 401 and 397 nm, and these peaks imply the appearance of optical energy gaps of 2.12 and 2.58 eV, accompanying spherical shapes of particles with diameters in the ranges of 12-20 and 50-80 nm, respectively. These silver nanoparticles together with the adopted green technique have a vast array of applications, specifically in the biomedical realm. In particular, they are being used to treat several diseases and are manifested as strong anti-tumor agents to medicate MCF-7 breast cancer cell lines in order to minimize the cell growth rate depending on their concentrations.

Current Trends and Prospects for Application of Green Synthesized Metal Nanoparticles in Cancer and COVID-19 Therapies

Cancer and COVID-19 have been deemed as world health concerns due to the millions of lives that they have claimed over the years. Extensive efforts have been made to develop sophisticated, site-specific, and safe strategies that can effectively diagnose, prevent, manage, and treat these diseases. These strategies involve the implementation of metal nanoparticles and metal oxides such as gold, silver, iron oxide, titanium oxide, zinc oxide, and copper oxide, formulated through nanotechnology as alternative anticancer or antiviral therapeutics or drug delivery systems. This review provides a perspective on metal nanoparticles and their potential application in cancer and COVID-19 treatments. The data of published studies were critically analysed to expose the potential therapeutic relevance of green synthesized metal nanoparticles in cancer and COVID-19. Although various research reports highlight the great potential of metal and metal oxide nanoparticles as alternative nanotherapeutics, issues of nanotoxicity, complex methods of preparation, biodegradability, and clearance are lingering challenges for the successful clinical application of the NPs. Thus, future innovations include fabricating metal nanoparticles with eco-friendly materials, tailor making them with optimal therapeutics for specific disease targeting, and in vitro and in vivo evaluation of safety, therapeutic efficiency, pharmacokinetics, and biodistribution.

Biosynthesis of zinc oxide nanoparticles using Indigofera tinctoria and their efficacy against dengue vector, Aedes aegypti (Diptera: Culicidae)

Dengue fever is a viral mosquito borne disease transmitted by day biting mosquito, Aedes aegypti. No medicine has been proven to be effective for the complete cure of dengue and mosquito control remains to be the only effective option. Increased cases of dengue contraction are being enormously reported worldwide every year. Thus, the urge for an effective measure remains a factor of major concern. In the present study, biosynthesized spherical-like structured zinc oxide (ZnO) nanoparticles using Indigofera tinctoria leaf extracts are employed as a mosquito controlling agent. The biosynthesized nanoparticles are characterized by UV-Vis, FTIR, FESEM, EDAX, XRD, Zeta Potential, and DLS analysis. The efficacy of the green synthesized ZnO nanoparticles were tested against different larval and pupal stages of A. aegypti. Further, it is established that a significant LC₅₀ values of 4.030 ppm in first instar and 7.213 ppm in pupae of A. aegypti is due to the impact of synthesized ZnO. Histological studies confirmed that effective and destructive changes were observed in larval body tissues particularly in the fat cells and the midgut. Therefore, this study highlights the application of biosynthesized ZnO nanoparticles as a potential candidate for safe and eco-friendly agent against the dengue vector, A. aegypti.

Silver Nanoparticles: Review of Antiviral Properties, Mechanism of Action and Applications

New antiviral drugs and new preventive antiviral strategies are a target of intense scientific interest. Thanks to their peculiar properties, nanomaterials play an important role in this field, and, in particular, among metallic materials, silver nanoparticles were demonstrated to be effective against a wide range of viruses, in addition to having a strong antibacterial effect. Although the mechanism of antiviral action is not completely clarified, silver nanoparticles can directly act on viruses, and on their first steps of interaction with the host cell, depending on several factors, such as size, shape, functionalization and concentration. This review provides an overview of the antiviral properties of silver nanoparticles, along with their demonstrated mechanisms of action and factors mainly influencing their properties. In addition, the fields of potential application are analyzed, demonstrating the versatility of silver nanoparticles, which can be involved in several devices and applications, including biomedical applications, considering both human and animal health, environmental applications, such as air filtration and water treatment, and for food and textile industry purposes. For each application, the study level of the device is indicated, if it is either a laboratory study or a commercial product.

Plant and Microbial Approaches as Green Methods for the Synthesis of Nanomaterials: Synthesis, Applications, and Future Perspectives

The unique biological and physicochemical characteristics of biogenic (green-synthesized) nanomaterials (NMs) have attracted significant interest in different fields, with applications in the agrochemical, food, medication delivery, cosmetics, cellular imaging, and biomedical industries. To synthesize biogenic nanomaterials, green synthesis techniques use microorganisms, plant extracts, or proteins as bio-capping and bio-reducing agents and their role as bio-nanofactories for material synthesis at the nanoscale size. Green chemistry is environmentally benign, biocompatible, nontoxic, and economically effective. By taking into account the findings from recent investigations, we shed light on the most recent developments in the green synthesis of nanomaterials using different types of microbes and plants. Additionally, we cover different applications of green-synthesized nanomaterials in the food and textile industries, water treatment, and biomedical applications. Furthermore, we discuss the future perspectives of the green synthesis of nanomaterials to advance their production and applications.

Nanoparticles: A Potential and Effective Method to Control Insect-Borne Diseases

Insects act as vectors to carry a wide range of bacteria and viruses that can cause multiple vector-borne diseases in humans. Diseases such as dengue fever, epidemic encephalitis B, and epidemic typhus, which pose serious risks to humans, can be transmitted by insects. Due to the absence of effective vaccines for most arbovirus, insect control was the main strategy for vector-borne diseases control. However, the rise of drug resistance in the vectors brings a great challenge to the prevention and control of vector-borne diseases. Therefore, finding an eco-friendly method for vector control is essential to combat vector-borne diseases. Nanomaterials with the ability to resist insects and deliver drugs offer new opportunities to increase agent efficacy compared with traditional agents, and the application of nanoagents has expanded the field of vector-borne disease control. Up to now, the reviews of nanomaterials mainly focus on biomedicines, and the control of insect-borne diseases has always been a neglected field. In this study, we analyzed 425 works of the literature about different nanoparticles applied on vectors in PubMed around keywords, such as"nanoparticles against insect," "NPs against insect," and "metal nanoparticles against insect." Through these articles, we focus on the application and development of nanoparticles (NPs) for vector control, discussing the lethal mechanism of NPs to vectors, which can explore the prospect of applying nanotechnology in the prevention and control of vectors.

Self-Therapeutic Nanomaterials: Applications in Biology and Medicine

Over past decades, nanotechnology has contributed to the biomedical field in areas including detection, diagnosis, and drug delivery via opto-electronic properties or enhancement of biological effects. Though generally considered inert delivery vehicles, a plethora of past and present evidence demonstrates that nanomaterials also exude unique intrinsic biological activity based on composition, shape, and surface functionalization. These intrinsic biological activities, termed self-therapeutic properties, take several forms, including mediation of cell-cell interactions, modulation of interactions between biomolecules, catalytic amplification of biochemical reactions, and alteration of biological signal transduction events. Moreover, study of biomolecule-nanomaterial interactions offers a promising avenue for uncovering the molecular mechanisms of biology and the evolution of disease. In this review, we observe the historical development, synthesis, and characterization of self-therapeutic nanomaterials. Next, we discuss nanomaterial interactions with biological systems, starting with administration and concluding with elimination. Finally, we apply this materials perspective to advances in intrinsic nanotherapies across the biomedical field, from cancer therapy to treatment of microbial infections and tissue regeneration. We conclude with a description of self-therapeutic nanomaterials in clinical trials and share our perspective on the direction of the field in upcoming years.

Antiviral role of nanomaterials: a material scientist's perspective

The present world continues to face unprecedented challenges caused by the COVID-19 pandemic. Collaboration between researchers of multiple disciplines is the need of the hour. There is a need to develop antiviral agents capable of inhibiting viruses and tailoring existing antiviral drugs for efficient delivery to prevent a surge in deaths caused by viruses globally. Biocompatible systems have been designed using nanotechnological principles which showed appreciable results against a wide range of viruses. Many nanoparticles can act as antiviral therapeutic agents if synthesized by the correct approach. Moreover, nanoparticles can act as carriers of antiviral drugs while overcoming their inherent drawbacks such as low solubility, poor bioavailability, uncontrolled release, and side effects. This review highlights the potential of nanomaterials in antiviral applications by discussing various studies and their results regarding antiviral potential of nanoparticles while also suggesting future directions to researchers.

Nano-antivirals: A comprehensive review

Nanoparticles can be used as inhibitory agents against various microorganisms, including bacteria, algae, archaea, fungi, and a huge class of viruses. The mechanism of action includes inhibiting the function of the cell membrane/stopping the synthesis of the cell membrane, disturbing the transduction of energy, producing toxic reactive oxygen species (ROS), and inhibiting or reducing RNA and DNA production. Various nanomaterials, including different metallic, silicon, and carbon-based nanomaterials and nanoarchitectures, have been successfully used against different viruses. Recent research strongly agrees that these nanoarchitecture-based virucidal materials (nano-antivirals) have shown activity in the solid state. Therefore, they are very useful in the development of several products, such as fabric and high-touch surfaces. This review thoroughly and critically identifies recently developed nano-antivirals and their products, nano-antiviral deposition methods on various substrates, and possible mechanisms of action. By considering the commercial viability of nano-antivirals, recommendations are made to develop scalable and sustainable nano-antiviral products with contact-killing properties.

Environmental Implications Associated with the Development of Nanotechnology: From Synthesis to Disposal

Nanotechnology remains under continuous development. The unique, fascinating, and tunable properties of nanomaterials make them interesting for diverse applications in different fields such as medicine, agriculture, and remediation. However, knowledge about the risks associated with nanomaterials is still poorly known and presents variable results. Furthermore, the interaction of nanomaterials with biological systems and the environment still needs to be clarified. Moreover, some issues such as toxicity, bioaccumulation, and physicochemical transformations are found to be dependent on several factors such as size, capping agent, and shape, making the comparisons even more complex. This review presents a comprehensive discussion about the consequences of the use and development of nanomaterials regarding their potential risks to the environment as well as human and animal health. For this purpose, we reviewed the entire production chain from manufacturing, product development, applications, and even product disposal to raise the important implications at each stage. In addition, we present the recent developments in terms of risk management and the recycling of nanomaterials. Furthermore, the advances and limitations in the legislation and characterization of nanomaterials are also discussed.

Citrullus colocynthis-Mediated Green Synthesis of Silver Nanoparticles and Their Antiproliferative Action against Breast Cancer Cells and Bactericidal Roles against Human Pathogens

The present study investigated the biomedical potential of eco-friendly Citrullus colocynthis-mediated silver nanoparticles (Cc-AgNPs). The antibacterial efficacy of Cc-AgNPs was evaluated against two multidrug-resistant pathogenic bacterial strains, Escherichia coli and Pseudomonas aeruginosa. The antiproliferative and antilipidemic performance of the prepared particles was determined against the MCF7 cell line, a breast cancer cell line. The in vitro antibacterial assay revealed that Cc-AgNPs induced dose-dependent bactericidal activity, as a considerable increase in the zone of inhibition (ZOI) was noted at higher concentrations. Reduced proliferation, migration, spheroid size, and colony formation exhibited the substantial antiproliferative potential of Cc-AgNPs against MCF7 cells. Significant alterations in the expression of cell surface markers, apoptosis, and cell proliferation genes further confirmed the antiproliferative impact of Cc-AgNPs. Moreover, Cc-AgNPs exhibited antilipidemic activity by reducing cellular cholesterol and triglyceride levels and regulating key genes involved in lipogenesis. In conclusion, these results propose that Cc-AgNPs can be employed as a potent tool for future antibacterial and anticancer applications.

Potential application of chitosan stabilized silver nanoparticles for simultaneous control of dengue virus and mosquito vectors

Dengue fever pandemic caused by dengue virus has been claimed for many lives, however, no specific treatment is available. Prevention based on vector control posed to be the most effective measure so far. The application of chitosan stabilized silver nanoparticle (AgNPs) to control larvae and adult mosquitoes has recently discovered, but their ability to inhibit Dengue virus has scarcely discussed. In this study, chitosan stabilized AgNPs have been prepared and tested against dengue virus type 1. The results showed that chitosan stabilized AgNPs can inhibit 96.66% and 98.33% dengue virus type 1 at 12.50 ppm and 25.00 ppm, respectively, without any toxicity to BHKFcɣ cells. This study confirms that chitosan stabilized AgNPs have a highly antiviral ability against dengue virus in addition to its mosquitocidal properties. This allows one to control both virus and vector simultaneously. The study suggested that chitosan stabilized AgNPs could be an effective tool to prevent the dengue epidemic.

Green Nano-Biotechnology: A New Sustainable Paradigm to Control Dengue Infection

Dengue is a growing mosquito-borne viral disease prevalent in 128 countries, while 3.9 billion people are at high risk of acquiring the infection. With no specific treatment available, the only way to mitigate the risk of dengue infection is through controlling of vector, i.e., Aedes aegypti. Nanotechnology-based prevention strategies like biopesticides with nanoformulation are now getting popular for preventing dengue fever. Metal nanoparticles (NPs) synthesized by an eco-friendly process, through extracts of medicinal plants have indicated potential anti-dengue applications. Green synthesis of metal NPs is simple, cost-effective, and devoid of hazardous wastes. The recent progress in the phyto-synthesized multifunctional metal NPs for anti-dengue applications has encouraged us to review the available literature and mechanistic aspects of the dengue control using green-synthesized NPs. Furthermore, the molecular bases of the viral inhibition through NPs and the nontarget impacts or hazards with reference to the environmental integrity are discussed in depth. Till date, major focus has been on green synthesis of silver and gold NPs, which need further extension to other innovative composite nanomaterials. Further detailed mechanistic studies are required to critically evaluate the mechanistic insights during the synthesis of the biogenic NPs. Likewise, detailed analysis of the toxicological aspects of NPs and their long-term impact in the environment should be critically assessed.

Plant Extract-Based Synthesis of Metallic Nanomaterials, Their Applications, and Safety Concerns

Nanotechnology has attracted the attention of researchers from different scientific fields because of the escalated properties of nanomaterials compared with the properties of macromolecules. Nanomaterials can be prepared through different approaches involving physical and chemical methods. The development of nanomaterials through plant-based green chemistry approaches is more advantageous than other methods from the perspectives of environmental safety, animal, and human health. The biomolecules and metabolites of plants act as reducing and capping agents for the synthesis of metallic green nanomaterials. Plant-based synthesis is a preferred approach as it is not only cost-effective, easy, safe, clean, and eco-friendly but also provides pure nanomaterials in high yield. Since nanomaterials have antimicrobial and antioxidant potential, green nanomaterials synthesized from plants can be used for a variety of biomedical and environmental remediation applications. Past studies have focused mainly on the overall biogenic synthesis of individual or combinations of metallic nanomaterials and their oxides from different biological sources, including microorganisms and biomolecules. Moreover, from the viewpoint of biomedical applications, the literature is mainly focusing on synthetic nanomaterials. Herein, we discuss the extraction of green molecules and recent developments in the synthesis of different plant-based metallic nanomaterials, including silver, gold, platinum, palladium, copper, zinc, iron, and carbon. Apart from the biomedical applications of metallic nanomaterials, including antimicrobial, anticancer, diagnostic, drug delivery, tissue engineering, and regenerative medicine applications, their environmental remediation potential is also discussed. Furthermore, safety concerns and safety regulations pertaining to green nanomaterials are also discussed. This article is protected by copyright. All rights reserved.

Mycosynthesis, Characterization, and Mosquitocidal Activity of Silver Nanoparticles Fabricated by Aspergillus niger Strain

Herein, silver nanoparticles (Ag-NPs) were synthesized using an environmentally friendly approach by harnessing the metabolites of Aspergillus niger F2. The successful formation of Ag-NPs was checked by a color change to yellowish-brown, followed by UV-Vis spectroscopy, Fourier transforms infrared (FT-IR), Transmission electron microscopy (TEM), and X-ray diffraction (XRD). Data showed the successful formation of crystalline Ag-NPs with a spherical shape at the maximum surface plasmon resonance of 420 nm with a size range of 3–13 nm. The Ag-NPs showed high toxicity against I, II, III, and IV instar larvae and pupae of Aedes aegypti with LC50 and LC90 values of 12.4–22.9 ppm and 22.4–41.4 ppm, respectively under laboratory conditions. The field assay exhibited the highest reduction in larval density due to treatment with Ag-NPs (10× LC50) with values of 59.6%, 74.7%, and 100% after 24, 48, and 72 h, respectively. The exposure of A. aegypti adults to the vapor of burning Ag-NPs-based coils caused a reduction of unfed individuals with a percentage of 81.6 ± 0.5% compared with the positive control, pyrethrin-based coils (86.1 ± 1.1%). The ovicidal activity of biosynthesized Ag-NPs caused the hatching of the eggs with percentages of 50.1 ± 0.9, 33.5 ± 1.1, 22.9 ± 1.1, and 13.7 ± 1.2% for concentrations of 5, 10, 15, and 20 ppm, whereas Ag-NPs at a concentration of 25 and 30 ppm caused complete egg mortality (100%). The obtained data confirmed the applicability of biosynthesized Ag-NPs to the biocontrol of A. aegypti at low concentrations.

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 of new series of quinoline derivatives with insecticidal effects on larval vectors of malaria and dengue diseases

Mosquito borne diseases are on the rise because of their fast spread worldwide and the lack of effective treatments. Here we are focusing on the development of a novel anti-malarial and virucidal agent with biocidal effects also on its vectors. We have synthesized a new quinoline (4,7-dichloroquinoline) derivative which showed significant larvicidal and pupicidal properties against a malarial and a dengue vector and a lethal toxicity ranging from 4.408 µM/mL (first instar larvae) to 7.958 µM/mL (pupal populations) for Anopheles stephensi and 5.016 µM/mL (larva 1) to 10.669 µM/mL (pupae) for Aedes aegypti. In-vitro antiplasmodial efficacy of 4,7-dichloroquinoline revealed a significant growth inhibition of both sensitive strains of Plasmodium falciparum with IC50 values of 6.7 nM (CQ-s) and 8.5 nM (CQ-r). Chloroquine IC50 values, as control, were 23 nM (CQ-s), and 27.5 nM (CQ-r). In vivo antiplasmodial studies with P. falciparum infected mice showed an effect of 4,7-dichloroquinoline compared to chloroquine. The quinoline compound showed significant activity against the viral pathogen serotype 2 (DENV-2). In vitro conditions and the purified quinoline exhibited insignificant toxicity on the host system up to 100 µM/mL. Overall, 4,7-dichloroquinoline could provide a good anti-vectorial and anti-malarial agent.

Plant-Mediated Green Synthesis of Ag NPs and Their Possible Applications: A Critical Review

The potential applications of Ag NPs are exciting and beneficial in a variety of fields; however, there is less awareness of the new risks posed by inappropriate disposal of Ag NPs. The Ag NPs have medicinal, plasmonic, and catalytic properties. The Ag NPs can be prepared via physical, chemical, or biological routes, and the selection of any specific route depends largely on the end-use. The downside of a physical and chemical approach is that it requires a wide space, high temperature, high temperature for a longer time to preserve the thermal stability of synthesized Ag NPs, and the use of toxic chemicals. Although these methods produce nanoparticles with high purity and well-defined morphology, it is critical to develop cost-effective, energy-efficient, and facile route, such as green synthesis; it suggests the desirable use of renewable resources by avoiding the use of additional solvents and toxic reagents in order to achieve the ultimate goal. However, each method has its pros and cons. The synthesized Ag NPs obtained using the green approach have larger biocompatibility and are less toxic towards the biotic systems. However, identifying the phytoconstituents that are responsible for nanoparticle synthesis is difficult and has been reported as a suitable candidate for biological application. The concentration of the effective bioreducing phytoconstituents plays a crucial role in deciding the morphology of the nanoparticle. Besides these reaction times, temperature, pH, and concentration of silver salt are some of the key factors that determine the morphology. Hence, careful optimization in the methodology is required as different morphologies have different properties and usage. It is due to which the development of methods to prepare nanoparticles effectively using various plant extracts is gaining rapid momentum in recent days. To make sense of what involves in the bioreduction of silver salt and to isolate the secondary metabolites from plants are yet challenging. This review focuses on the contribution of plant-mediated Ag NPs in different applications and their toxicity in the aquatic system.

The Emerging Roles of Silver Nanoparticles to Target Viral Life Cycle and Detect Viral Pathogens

Along the line of recent vaccine advancements, new antiviral therapeutics are compelling to combat viral infection-related public health crises. Several properties of silver nanoparticles (AgNPs) such as low level of cytotoxicity, ease of tunability of the AgNPs in the ultra-small nanoscale size and shape through different convenient bottom-up chemistry approaches, high penetration of the composite with drug formulations into host cells has made AgNPs, a promising candidate for developing antivirals. In this review, we have highlighted the recent advancements in the AgNPs based nano-formulations to target cellular mechanisms of viral propagation, immune modulation of the host, and the ability to synergistically enhance the activity of existing antiviral drugs. On the other hand, we have discussed the recent advancements on AgNPs based detection of viral pathogens from clinical samples using inherent physicochemical properties. This article will provide an overview of our current knowledge on AgNPs based formulations that has promising potential for developing a counteractive strategy against emerging and existing viruses.

Biosynthesis and Characterizations of Silver Nanoparticles from Annona squamosa Leaf and Fruit Extracts for Size-Dependent Biomedical Applications

Green synthesis differs in the way that the plant produces chemicals that act as reducing and stabilizing agents, and by adopting this green synthesis, we have synthesized silver nanoparticles (AgNPs) from the leaf and fruit extracts of Annona squamosa (also known as Sharifa), where these extracts have played an important role as reducing and capping agents. The nanoparticles were synthesized as the consequence of a reduction that happened between plant extracts and the precursor solution. The prepared AgNPs were then characterized using scanning electron microscopy, UV-Visible spectroscopy, and X-ray diffraction to study their morphology, optical response, and crystallinity. A single distinctive absorption peak of colloidal AgNPs samples was observed at 430 nm and 410 nm for leaf and fruit extract samples, having an optical bandgap of 2.97 eV and 2.88 eV, respectively, with a spherical shape having a diameter in the range of 35–90 nm and 15–50 nm, respectively, whilst XRD studies supported the FCC cubic structure of the mediated AgNPs. These green synthesized AgNPs have a wide variety of uses, particularly in the biomedical domain, where they have the potential to treat numerous diseases and are reported to be efficient against antibacterial, anti-cancer, and anti-diabetic activities.

Recent advances on therapeutic potentials of gold and silver nanobiomaterials for human viral diseases

Viral diseases are prominent among the widely spread infections threatening human well-being. Real-life clinical successes of the few available therapeutics are challenged by pathogenic resistance and suboptimal delivery to target sites. Nanotechnology has aided the design of functionalised and non-functionalised Au and Ag nanobiomaterials through physical, chemical and biological (green synthesis) methods with improved antiviral efficacy and delivery. In this review, innovative designs as well as interesting antiviral activities of the nanotechnology-inclined biomaterials of Au and Ag, reported in the last 5 years were critically overviewed against several viral diseases affecting man. These include influenza, respiratory syncytial, adenovirus, severe acute respiratory syndromes (SARS), rotavirus, norovirus, measles, chikungunya, HIV, herpes simplex virus, dengue, polio, enterovirus and rift valley fever virus. Notably identified among the nanotechnologically designed promising antiviral agents include AuNP-M2e peptide vaccine, AgNP of cinnamon bark extract and AgNP of oseltamivir for influenza, PVP coated AgNP for RSV, PVP-AgNPs for SARS-CoV-2, AuNRs of a peptide pregnancy-induce d hypertension and AuNP nanocarriers of antigen for MERS-CoV and SARS-CoV respectively. Others are AgNPs of collagen and Bacillus subtilis for rotavirus, AgNPs labelled Ag30-SiO 2 for murine norovirus in water, AuNPs of Allium sativum and AgNPs of ribavirin for measles, AgNPs of Citrus limetta and Andrographis Paniculata for Chikungunya, AuNPs of efavirenz and stavudine, and AgNPs-curcumin for HIV, NPAuG3-S8 for HSV, AgNPs of Moringa oleifera and Bruguiera cylindrica for dengue while AgNPs of polyethyleneimine and siRNA analogues displayed potency against enterovirus. The highlighted candidates are recommended for further translational studies towards antiviral therapeutic designs.

Synthesis, Characterization and Biomedical Application of Silver Nanoparticles

Silver nanoparticles (AgNPs) have been employed in various fields of biotechnology due to their proven properties as an antibacterial, antiviral and antifungal agent. AgNPs are generally synthesized through chemical, physical and biological approaches involving a myriad of methods. As each approach confers unique advantages and challenges, a trends analysis of literature for the AgNPs synthesis using different types of synthesis were also reviewed through a bibliometric approach. A sum of 10,278 publications were analyzed on the annual numbers of publication relating to AgNPs and biological, chemical or physical synthesis from 2010 to 2020 using Microsoft Excel applied to the Scopus publication database. Furthermore, another bibliometric clustering and mapping software were used to study the occurrences of author keywords on the biomedical applications of biosynthesized AgNPs and a total collection of 224 documents were found, sourced from articles, reviews, book chapters, conference papers and reviews. AgNPs provides an excellent, dependable, and effective solution for seven major concerns: as antibacterial, antiviral, anticancer, bone healing, bone cement, dental applications and wound healing. In recent years, AgNPs have been employed in biomedical sector due to their antibacterial, antiviral and anticancer properties. This review discussed on the types of synthesis, how AgNPs are characterized and their applications in biomedical field.

Risk Factors Associated with a Dengue Fever Outbreak in Islamabad, Pakistan: Case-Control Study

Background

On October 23, 2016, 79 dengue fever cases were reported from the Union Council Tarlai to Federal Disease Surveillance and Response Unit Islamabad. A team was established to investigate the suspected dengue outbreak.

Objective

The aim of this study was to determine the extent of the outbreak and identify the possible risk factors.

Methods

Active case finding was performed through a house-to-house survey. A case was defined as an acute onset of fever ≥38℃ in a resident of Tarlai from October 2 to November 11, 2016, with a positive dengue virus (nonstructural protein, NS-1) test and any of the two of following signs and symptoms: retroorbital/ocular pain, headache, rash, myalgia, arthralgia, and hemorrhagic manifestations. A structured questionnaire was used to collect data. Age- and sex-matched controls (1:1) were identified from residents in the same area as cases. Blood samples were taken and sent to the National Institute of Health for genotype identification.

Results

During the active case search, 145 cases of dengue fever were identified by surveying 928 houses from October 23 to November 11, 2016. The attack rate (AR) was 17.0/10,000. The mean age was 34.4 (SD 14.4) years. More than half of the cases were male (80/145, 55.2%). Among all cases, 29% belonged to the 25-34 years age group and the highest AR was found in the 35-44 years age group (35.6/10,000), followed by the 55-64 years age group (35.5/10,000). All five blood samples tested positive for NS-1 (genotype DENV-2). The most frequent presenting signs/symptoms were fever and headache (both 100%). Stagnant water around houses (odds ratio [OR] 4.86, 95% CI 2.94-8.01; P<.001), presence of flower pots in the home (OR 2.73, 95% CI 1.67-4.45; P<.001), and open water containers (OR 2.24, 95% CI 1.36-3.60; P<.001) showed higher odds among cases. Conversely, use of bed nets (OR 0.44, 95% CI 0.25-0.77; P=.003), insecticidal spray (OR 0.33, 95% CI 0.22-0.55; P<.001), door screens (OR 0.27, 95% CI 0.15-0.46; P<.001), mosquito coil/mat (OR 0.26, 95% CI 0.16-0.44; P<.001), and cleanliness of the house (OR 0.12, 95% CI 0.05-0.26; P<.001) showed significant protective effects.

Conclusions

Stagnant water acting as breeding grounds for vectors was identified as the probable cause of spread of the dengue outbreak. Establishment of surveillance and an early reporting system along with use of protective measures against the vector are strongly recommended.

Road map to the treatment of neglected tropical diseases: Nanocarriers interventions

Neglected tropical disease (NTD) is a set of 20 deadliest endemic diseases which shows its presence in most of the developing countries worldwide. Nearly 1 billion of the population are affected by it and suffered from poverty yearly. These diseases offer their own unique challenges and limitations towards effective prevention and treatment methods. Neglected tropical diseases are severe infections they may not kill the patient but debilitate the patient by causing severe skin deformities, disfigurement and horrible risks for several infections. Existing therapies for neglected diseases suffer from the loopholes like high degree of toxicity, side effects, low bioavailability, improper targeting and problematic application for affected populations. Progress in the field of nanotechnology in last decades suggested the intervention of nanocarriers to take over and drive the research and development to the next level by incorporating established drugs into the nanocarriers rather than discovering the newer drugs which is an expensive affair. These nanocarriers are believed to be a sure shot technique to fight infections at root level by virtue of its nanosize and ability to reach at cellular level. This article highlights the recent advances, rationale, targets and the challenges that are being faced to fight against NTDs and how the novel therapy tactics are able to contribute to its importance in prevention and treatment of NTDs.

Nanotechnology Applications of Flavonoids for Viral Diseases

Recent years have witnessed the emergence of several viral diseases, including various zoonotic diseases such as the current pandemic caused by the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2). Other viruses, which possess pandemic-causing potential include avian flu, Ebola, dengue, Zika, and Nipah virus, as well as the re-emergence of SARS (Severe Acute Respiratory Syndrome) and MERS (Middle East Respiratory Syndrome) coronaviruses. Notably, effective drugs or vaccines against these viruses are still to be discovered. All the newly approved vaccines against the SARS-CoV-2-induced disease COVID-19 possess real-time possibility of becoming obsolete because of the development of ‘variants of concern’. Flavonoids are being increasingly recognized as prophylactic and therapeutic agents against emerging and old viral diseases. Around 10,000 natural flavonoid compounds have been identified, being phytochemicals, all plant-based. Flavonoids have been reported to have lesser side effects than conventional anti-viral agents and are effective against more viral diseases than currently used anti-virals. Despite their abundance in plants, which are a part of human diet, flavonoids have the problem of low bioavailability. Various attempts are in progress to increase the bioavailability of flavonoids, one of the promising fields being nanotechnology. This review is a narrative of some anti-viral dietary flavonoids, their bioavailability, and various means with an emphasis on the nanotechnology system(s) being experimented with to deliver anti-viral flavonoids, whose systems show potential in the efficient delivery of flavonoids, resulting in increased bioavailability.

Green synthesis and characterization of titanium dioxide nanoparticles using leaf extract of Pouteria campechiana and larvicidal and pupicidal activity on Aedes aegypti

The frequent application of synthetic insecticides creates resistance among insects, including mosquitoes, and causes environmental pollution and health issues. The current work aim at assessing the possibilities to produce and characterize the titanium dioxide (TiO₂) nanoparticles (TiO₂ NPs) mediated through the aqueous leaf extract of Pouteria campechiana, and their larvicidal and pupicidal activities against Aedes aegypti. The attained results showed that the aqueous leaf extract of P. campechiana had the efficiency to fabricate TiO₂ NPs from TiO₂. Under the UV-vis spectrum analysis, a sharp peak was recorded at 320 nm, which indicated the production of TiO₂ NPs by the plant extract. The SEM analysis revealed that the synthesized TiO₂ NPs were spherical, and 5 dissimilar diffractions were detected in the XRD spectrum analysis related to the TiO₂ NPs. In FTIR analysis, a prominent peak was found at 1052.41 cm^-1, corresponding to alcohol, and confirmed metal reduction. In the EDX analysis, there was a signal of around 58.44%, confirming the decrease in Ti from TiO₂ NPs, and the remaining percentages were Ca, Al, and Mg. About 900 μg mL^-1 of TiO₂ NPs had excellent lethal activity against various larvae and pupa stages of Ae. aegypti. The attained results showed that the P. campechiana aqueous leaf extract could reduce TiO₂ into TiO₂ NPs and could be considered a mosquito control agent. Furthermore, this is the initial report about the aqueous leaf extract of P. campechiana effectively synthesizing the TiO₂ NPs with anti-mosquito activity.

Silver Nanoparticles Biosynthesis, Characterization, Antimicrobial Activities, Applications, Cytotoxicity and Safety Issues: An Updated Review

Rapid advances in nanotechnology have led to its emergence as a tool for the development of green synthesized noble metal nanoparticles, especially silver nanoparticles (AgNPs), for applications in diverse fields such as human health, the environment and industry. The importance of AgNPs is because of their unique physicochemical and antimicrobial properties, with a myriad of activities that are applicable in various fields, including the pharmaceutical industry. Countries with high biodiversity require the collection and transformation of information about biological assets into processes, associations, methods and tools that must be combined with the sustainable utilization of biological diversity. Therefore, this review paper discusses the applicable studies of the biosynthesis of AgNPs and their antimicrobial activities towards microorganisms in different areas viz. medicine and agriculture. The confirmed antiviral properties of AgNPs promote their applicability for SARS-CoV-2 treatment, based on assimilating the virus’ activities with those of similar viruses via in vivo studies. In this review, an insight into the cytotoxicity and safety issues of AgNPs, along with their future prospects, is also provided.

Metal Nanoparticles: a Promising Treatment for Viral and Arboviral Infections

Globally, viral diseases continue to pose a significant threat to public health. Recent outbreaks, such as influenza, coronavirus, Ebola, and dengue, have emphasized the urgent need for new antiviral therapeutics. Considerable efforts have focused on developing metal nanoparticles for the treatment of several pathogenic viruses. As a result of these efforts, metal nanoparticles are demonstrating promising antiviral activity against pathogenic surrogates and clinical isolates. This review summarizes the application of metal nanoparticles for the treatment of viral infections. It provides information on synthesis methods, size-related properties, nano-bio-interaction, and immunological effects of metal nanoparticles. This article also addresses critical criteria and considerations for developing clinically translatable nanosized metal particles to treat viral diseases.

Silver nanoparticles biosynthesized from secondary metabolite producing marine actinobacteria and evaluation of their biomedical potential

Biosynthesis of silver nanoparticles (AgNPs) from marine actinobacteria offers a promising avenue for exploring bacterial extracts as reducing and stabilizing agents. We report extracellular extracts of Rhodococcus rhodochrous (MOSEL-ME29) and Streptomyces sp. (MOSEL-ME28), identified by 16S rRNA gene sequencing for synthesis of AgNPs. Ultrafine silver nanoparticles were biosynthesized using the extracts of R. rhodochrous and Streptomyces sp. and their possible therapeutic applications were studied. The physicochemical properties of nanoparticles were established by HR-SEM/TEM, SAED, UV-Vis, EDS, XRD, and FTIR. UV-Vis spectra displayed characteristic absorption at 430 nm and 412 nm for AgNPs from Streptomyces sp. (S-AgNPs) and Rhodococcus sp. (R-AgNPs), respectively. HR-SEM/TEM, XRD, EDS analysis confirmed the spherical shape, crystalline nature, and elemental formation of silver. Crystallite or grain size was deduced as 5.52 nm for R-AgNPs and 35 nm for S-AgNPs. Zeta-potential indicated electrostatic negative charge for AgNPs, while FTIR revealed the presence of diverse functional groups. Disc diffusion assay indicated the broad-spectrum antibacterial potential of S-AgNPs with the maximum inhibition of B. subtilis while R-AgNPs revealed potency against P. aeruginosa at 10 µg/mL concentration. Biogenic AgNPs revealed antileishmanial activity and the IC₅₀ was calculated as 164 µg/mL and 184 µg/mL for R-AgNPs and S-AgNPs respectively. Similarly, the R-AgNPs and S-AgNPs revealed anti-cancer potential against HepG2 and the IC₅₀ was calculated as 49 µg/mL and 69 µg/mL for R-AgNPs and S-AgNPs, respectively. Moreover, the antioxidant activity showed significant results. MTT assay on RD cells, L20B cells, and Hep-2C indicated intensification in viability by reducing the concentration of R-AgNPs and S-AgNPs. The R-AgNPs and S-AgNPs inhibited sabin-like poliovirus (1TCID₅₀ infection in RD cells). Furthermore, hemocompatibility at low concentrations has been confirmed. Hence, it is concluded that biogenic-AgNPs has the potential to be used in diverse biological applications and that the marine actinobacteria are an excellent resource for fabrication of AgNPs.

Carica papaya Leaf Extract Silver Synthesized Nanoparticles Inhibit Dengue Type 2 Viral Replication In Vitro

The current global occurrence of dengue infection annually is approximately 400 million, with a case fatality rate of 2.5%. However, there are no antiviral agents. Carica papaya leaf extract is known for its medicinal value, due to the presence of organic compounds that possess antimicrobial, anti-inflammatory, and antioxidant activities. This study determined the anti-dengue effect of C. papaya leaf extract silver synthesized nanoparticles. In this study, aqueous and non-aqueous extractions were carried out, followed by the synthesis of silver nanoparticles as well as characterization through Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy. The in vitro anti-dengue effect was evaluated using a focus reduction neutralization test on kidney Vero E2 cell lines. In silico studies involved molecular docking to determine the potential interactions between the bioactive compounds in C. papaya leaf extract and the viral NS5 protein. C. papaya leaf methanol extract silver synthesized nanoparticle was the most promising with an IC₅₀ of 9.20 µg/mL. Molecular docking showed 5,7 dimethoxycoumarin as the best ligand, with binding energy of −7.75 kcal/mol, indicating high affinity for the NS5 protein. These results highlight that C. papaya leaf methanol extract silver synthesized nanoparticles could be used to inhibit dengue virus type 2 viral replication. However, we recommend further studies to determine their toxicity and the safety profiles.

Silver, copper and copper oxide nanoparticles in the fight against human viruses: progress and perspectives

The rapid development of nanomedicine has created a high demand for silver, copper and copper oxide nanoparticles. Due to their high reactivity and potent antimicrobial activity, silver and copper-based nanomaterials have been playing an important role in the search for new alternatives for the treatment of several issues of concern, such as pathologies caused by bacteria and viruses. Viral diseases are a significant and constant threat to public health. The most recent example is the pandemic caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). In this context, the object of the present review is to highlight recent progress in the biomedical uses of these metal nanoparticles for the treatment and prevention of human viral infections. We discuss the antiviral activity of AgNPs and Cu-based NPs, including their actions against SARS-CoV-2. We also discuss the toxicity, biodistribution and excretion of AgNPs and CuNPs, along with their uses in medical devices or on inert surfaces to avoid viral dissemination by fomites. The challenges and limitations of the biomedical use of these nanoparticles are presented.

A review on nanostructured silver as a basic ingredient in medicine: physicochemical parameters and characterization

Recent studies with silver nanoparticles (AgNPs) and the history of silver metal as a broad-spectrum bactericidal and virucidal agent, places silver as one of the future biocidal candidates in the field of nanomedicine to eliminate bacteria and viruses, especially multidrug resistant ones. In this review, we have described the various morphologies of AgNPs and correlated the enhanced bactericidal activity with their prominent {111} facets. In addition to prioritizing the characterization we have also discussed the importance of quantifying AgNPs and silver ion content (Ag+) and their different mechanisms at the chemical, biological, pharmacological, and toxicological levels. The mechanism of action of AgNPs against various bacteria and viruses including the SARS-CoV-2 was analyzed in order to understand its effectiveness as an antimicrobial agent with therapeutic efficacy and low toxicity. Further, there is the need to characterize AgNPs and quantify the content of free Ag+ for the implementation of new systematic studies of this promising agent in nanomedicine and in clinical practice.

Green synthesized plant-based silver nanoparticles: therapeutic prospective for anticancer and antiviral activity

Nanotechnology holds an emerging domain of medical science as it can be utilized virtually in all areas. Phyto-constituents are valuable and encouraging candidates for synthesizing green silver nanoparticles (AgNPs) which possess great potentials toward chronic diseases. This review gives an overview of the Green approach of AgNPs synthesis and its characterization. The present review further explores the potentials of Phyto-based AgNPs toward anticancer and antiviral activity including its probable mechanism of action. Green synthesized AgNPs prepared by numerous medicinal plants extract are critically reviewed for cancer and viral infection. Thus, this article mainly highlights green synthesized Phyto-based AgNPs with their potential applications for cancer and viral infection including mechanism of action and therapeutic future prospective in a single window.

Nanotechnology as a tool for detection and treatment of arbovirus infections

Arboviruses are medically important viruses that cause high rates of infection all over the world. In addition, the severity of the symptoms and the inadequate diagnostic methods represent a challenge far beyond eradicating the vector. The lack of specific treatments for arbovirus infections reflects the imminent need for new research for safe and efficient medicines to treat these infections. Nanotechnology is an innovative approach currently used as a platform for developing new treatments, thus improving the biopharmaceutical properties of drugs. It can also be applied to the development of diagnostic devices, improving their detection capacity. The purpose of this paper is to review recent research on the use of nanotechnology for developing new treatments and detection devices for arbovirus infections. Interestingly, it was found that only a few studies report on the use of nanotechnology to treat arbovirus infections and that most of these reports focus on the fabrication of diagnostic tools. Also, some papers report on the use of nanotechnology for the development of vaccines, which in association with mosquito eradication programs could effectively reduce the high rates of infections by these viruses.

Biogenic selenium nanoparticles (SeNPs) from citrus fruit have anti-bacterial activities

Nanotechnology deals with the synthesis of materials and particles at nanoscale with dimensions of 1-100 nm. Biological synthesis of nanoparticles, using microbes and plants, is the most proficient method in terms of ease of handling and reliability. Core objectives of this study were to synthesize metallic nanoparticles using selenium metal salt from citrus fruit extracts, their characterization and evaluation for antimicrobial activities against pathogenic microbes. In methodology, simple green method was implicated using sodium selenite salt solution and citrus fruit extracts of Grapefruit and Lemon as precursors for synthesizing nanoparticles. Brick red color of the solution indicated towards the synthesis of selenium nanoparticles (SeNPs). Nanoparticle's initial characterization was done by UV-Vis Spectrophotometry and later FTIR analysis and DLS graphs via Zetasizer were obtained for the confirmation of different physical and chemical parameters of the nanoparticles. Different concentrations of SeNPs were used for antimicrobial testing against E. coli, M. luteus, B. subtilis and K. pneumoniae comparative with the standard antibiotic Ciprofloxacin. SeNPs possessed significant antimicrobial activities against all the bacterial pathogens used. Conclusively, SeNPs made from citrus fruits can act as potent antibacterial candidates.