Green synthesis of silver nanoparticles using Sida acuta (Malvaceae) leaf extract against Culex quinquefasciatus, Anopheles stephensi, and Aedes aegypti (Diptera: Culicidae)

Plant-based nanoparticles targeting malaria management

Malaria is one of the most devastating diseases across the globe, particularly in low-income countries in Sub-Saharan Africa. The increasing incidence of malaria morbidity is mainly due to the shortcomings of preventative measures such as the lack of vaccines and inappropriate control over the parasite vector. Additionally, high mortality rates arise from therapeutic failures due to poor patient adherence and drug resistance development. Although the causative pathogen (Plasmodium spp.) is an intracellular parasite, the recommended antimalarial drugs show large volumes of distribution and low-to no-specificity towards the host cell. This leads to severe side effects that hamper patient compliance and promote the emergence of drug-resistant strains. Recent research efforts are promising to enable the discovery of new antimalarial agents; however, the lack of efficient means to achieve targeted delivery remains a concern, given the risk of further resistance development. New strategies based on green nanotechnologies are a promising avenue for malaria management due to their potential to eliminate malaria vectors (Anopheles sp.) and to encapsulate existing and emerging antimalarial agents and deliver them to different target sites. In this review we summarized studies on the use of plant-derived nanoparticles as cost-effective preventative measures against malaria parasites, starting from the vector stage. We also reviewed plant-based nanoengineering strategies to target malaria parasites, and further discussed the site-specific delivery of natural products using ligand-decorated nanoparticles that act through receptors on the host cells or malaria parasites. The exploration of traditionally established plant medicines, surface-engineered nanoparticles and the molecular targets of parasite/host cells may provide valuable insights for future discovery of antimalarial drugs and open new avenues for advancing science toward the goal of malaria eradication.

Green synthesis of zinc oxide nanoparticles from Sida acuta leaf extract for antibacterial and antioxidant applications, and catalytic degradation of dye through the use of convolutional neural network

This study synthesized zinc oxide nanoparticles (ZnO NPs) using a novel green approach, with Sida acuta leaf extract as a capping and reducing agent to initiate nucleation and structure formation. The innovation of this study lies in demonstrating the originality of utilizing zinc oxide nanoparticles for antibacterial action, antioxidant potential, and catalytic degradation of Congo red dye. This unique approach harnesses eco-friendly methods to initiate nucleation and structure formation. The synthesized nanoparticles' structure and conformation were characterized using UV-vis (λmax = 280 nm), X-ray, atomic force microscopy, SEM, HR-TEM and FTIR. The antibacterial activity of the Nps was tested against Pseudomonas sp, Klebsiella sp, Staphylococcus aureus, and E. coli, demonstrating efficacy. The nanoparticles exhibited unique properties, with a crystallite size of 20 nm (XRD), a surface roughness of 2.5 nm (AFM), and a specific surface area of 60 m2/g (SEM). A Convolutional Neural Network (CNN) was effectively employed to accurately classify and analyze microscopic images of green-synthesized zinc oxide nanoparticles. This research revealed their exceptional antioxidant potential, with an average DPPH scavenging rate of 80% at a concentration of 0.05 mg/mL. Additionally, zeta potential measurements indicated a stable net negative surface charge of approximately -12.2 mV. These quantitative findings highlight the promising applications of green-synthesized ZnO NPs in healthcare, materials science, and environmental remediation. The ZnO nanoparticles exhibited catalytic capabilities for dye degradation, and the degradation rate was determined using UV spectroscopy. Key findings of the study encompass the green synthesis of versatile zinc oxide nanoparticles, demonstrating potent antibacterial action, antioxidant capabilities, and catalytic dye degradation potential. These nanoparticles offer multifaceted solutions with minimal environmental impact, addressing challenges in various fields, from healthcare to environmental remediation.

New weapons against the disease vector Aedes aegypti: From natural products to nanoparticles

Despite the global burden of viral diseases transmitted by Aedes aegypti, there is a lack of effective means of prevention and treatment. Strategies for vector control include chemical and biological approaches such as organophosphates and Bacillus thuringiensis var. israelensis (Bti), among others. However, important concerns are associated, such as resistance in mosquito larvae and deleterious effects on non-target organisms. In this scenario, novel approaches against A. aegypti have been investigated, including natural products (e.g. vegetable oil and extracts) and nanostructured systems. This review focuses on potential strategies for fighting A. aegypti, highlighting plant-based materials and nanomaterials able to induce toxic effects on egg, larva, pupa and adult mosquitoes. Issues including aspects of conventional vector control strategies are presented, and finally new insights on development of eco-friendly nanoformulations against A. aegypti are discussed.

Promising photocatalytic and antimicrobial activity of novel capsaicin coated cobalt ferrite nanocatalyst

In this study, CoFe₂O₄ nanoparticles were prepared by the co-precipitation method then surface modified with Capsaicin (Capsicum annuum ssp.). The virgin CoFe₂O₄ NPs and Capsaicin-coated CoFe₂O₄ NPs (CPCF NPs) were characterized by XRD, FTIR, SEM, and TEM. The antimicrobial potential and photocatalytic degradation efficiencies of the prepared samples via Fuchsine basic (FB) were investigated. The results revealed that CoFe₂O₄ NPs have spherical shapes and their diameter varied from 18.0 to 30.0 nm with an average particle size of 25.0 nm. Antimicrobial activity was tested on Gram-positive (S. aureusATCC 52923) and Gram-negative (E. coli ATCC 52922) by disk diffusion and broth dilution methods to determine the zone of inhibition (ZOI) and minimum inhibitory concentration (MIC), respectively. UV-assisted photocatalytic degradation of FB was examined. Various parameters affecting the photocatalytic efficiency such as pH, initial concentration of FB, and dose of nanocatalyst were studied. The in-vitro ZOI and MIC results verified that CPCF NPs were more active upon Gram-Positive S. aureus ATCC 52923 (23.0 mm ZOI and 0.625 μg/ml MIC) than Gram-Negative E. coli ATCC 52922 (17.0 mm ZOI and 1.250 μg/ml MIC). Results obtained from the photocatalytic activity indicated that the maximum FB removal achieving 94.6% in equilibrium was observed using 20.0 mg of CPCF NPS at pH 9.0. The synthesized CPCF NPs were effective in the removal of FB and also as potent antimicrobial agent against both Gram-positive and Gram-negative bacteria with potential medical and environmental applications.

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

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

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

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

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

Medicinal Plants of Solanum Species: The Promising Sources of Phyto-Insecticidal Compounds

Several medicinal plants have the potential to be a promising alternative pharmacological therapy for a variety of human illnesses. Many insects, including mosquitoes, are important vectors of deadly pathogens and parasites, which in the world's growing human and animal populations can cause serious epidemics and pandemics. Medicinal plants continue to provide a large library of phytochemicals, which can be used to replace chemically synthesized insecticides, and utilization of herbal product-based insecticides is one of the best and safest alternatives for mosquito control. Identifying new effective phyto-derived insecticides is important to counter increasing insect resistance to synthetic compounds and provide a safer environment. Solanum genus (Solanaceae family or nightshades) comprises more than 2500 species, which are widely used as food and traditional medicine. All research publications on insecticidal properties of Solanaceae plants and their phytoconstituents against mosquitoes and other insects published up to July 2020 were systematically analyzed through PubMed/MEDLINE, Scopus, EBSCO, Europe PMC, and Google Scholar databases, with focus on species containing active phytoconstituents that are biodegradable and environmentally safe. The current state of knowledge on larvicidal plants of Solanum species, type of extracts, target insect species, type of effects, name of inhibiting bioactive compounds, and their lethal doses (LC50 and LC90) were reviewed in this study. These studies provide valuable information about the activity of various species of Solanum and their phytochemical diversity, as well as a roadmap for optimizing select compounds for botanical repellents against a variety of vectors that cause debilitating and life-threatening human diseases.

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.

Multifarious global flora fabricated phytosynthesis of silver nanoparticles: a green nanoweapon for antiviral approach including SARS-CoV-2

The progressive research into the nanoscale level upgrades the higher end modernized evolution with every field of science, engineering, and technology. Silver nanoparticles and their broader range of application from nanoelectronics to nano-drug delivery systems drive the futuristic direction of nanoengineering and technology in contemporary days. In this review, the green synthesis of silver nanoparticles is the cornerstone of interest over physical and chemical methods owing to its remarkable biocompatibility and idiosyncratic property engineering. The abundant primary and secondary plant metabolites collectively as multifarious phytochemicals which are more peculiar in the composition from root hair to aerial apex through various interspecies and intraspecies, capable of reduction, and capping with the synthesis of silver nanoparticles. Furthermore, the process by which intracellular, extracellular biological macromolecules of the microbiota reduce with the synthesis of silver nanoparticles from the precursor molecule is also discussed. Viruses are one of the predominant infectious agents that gets faster resistance to the antiviral therapies of traditional generations of medicine. We discuss the various stages of virus targeting of cells and viral target through drugs. Antiviral potential of silver nanoparticles against different classes and families of the past and their considerable candidate for up-to-the-minute need of complete addressing of the fulminant and opportunistic global pandemic of this millennium SARS-CoV2, illustrated through recent silver-based formulations under development and approval for countering the pandemic situation.

Graphical abstract

Biocontrol of mosquito vectors through herbal-derived silver nanoparticles: prospects and challenges

Mosquitoes spread several life-threatening diseases such as malaria, filaria, dengue, Japanese encephalitis, West Nile fever, chikungunya, and yellow fever and are associated with millions of deaths every year across the world. However, insecticides of synthetic origin are conventionally used for controlling various vector-borne diseases but they have various associated drawbacks like impact on non-targeted species, negative effects on the environment, and development of resistance in vector species by alteration of the target site. Plant extracts, phytochemicals, and their nanoformulations can serve as ovipositional attractants, insect growth regulators, larvicides, and repellents with least effects on the environment. Such plant-derived products exhibit broad-spectrum resistance against various mosquito species and are relatively cheaper, environmentally safer, biodegradable, easily accessible, and are non-toxic to non-targeted organisms. Therefore, in this review article, the current knowledge of phytochemical sources exhibiting larvicidal activity and their variations in response to solvents used for their extraction is underlined. Also, different methods such as physical, chemical, and biological for silver nanoparticle (AgNPs) synthesis, their mechanism of synthesis using plant extract, their potent larvicidal activity, and the possible mechanism by which these particles kill mosquito larvae are discussed. In addition, constraints related to commercialization of nanoherbal products at government and academic or research level and barriers from laboratory experiments to field trial have also been discussed. This comprehensive information can be gainfully employed for the development of herbal larvicidal formulations and nanopesticides against insecticide-resistant vector species in the near future. Graphical abstract.

Leaf Extract of Dillenia indica as a Source of Selenium Nanoparticles with Larvicidal and Antimicrobial Potential toward Vector Mosquitoes and Pathogenic Microbes

Chikungunya, dengue, Zika, malaria, Japanese encephalitis, filariasis, West Nile, etc. are mosquito transmitted diseases that have killed millions of people worldwide, and millions of people are at risk of these diseases. Control of the mosquitoes, such as Aedes aegypti and Culex quinquefasciatus, is challenging due to their development of resistance to synthetic insecticides. The habitats of the young mosquitoes are also the habitats for foodborne pathogens like Staphylococcus aureus (MTCC96) and Serratia marcescens (MTCC4822). The present study was aimed at synthesizing eco-friendly green nanoparticles using Dillenia indica leaf broth and analyzing its efficacy in controlling the vector mosquitoes A. aegypti and C. quinquefasciatus, as well as the microbial pathogens St. aureus and Se. marcescens. The formation of selenium nanoparticles (SeNps) was confirmed using UV-Vis spectroscopy (absorption peak at 383.00 nm), Fourier transform infrared radiation (FTIR spectrum peaks at 3177, 2114, 1614, 1502, 1340, 1097, 901, 705, and 508 cm−1), X-ray diffraction (diffraction peaks at 23.3 (100), 29.6 (101), 43.5 (012), and 50.05 (201)), and scanning electron microscopy (oval shaped). The size of the nanoparticles and their stability were analyzed using dynamic light scattering (Z-Average value of 248.0 nm) and zeta potential (−13.2 mV). The SeNps disorganized the epithelial layers and have broken the peritrophic membrane. Histopathological changes were also observed in the midgut and caeca regions of the SeNPs treated A. aegypti and C. quinquefasciatus larvae. The SeNps were also active on both the bacterial species showing strong inhibitory zones. The present results will explain the ability of SeNps in controlling the mosquitoes as well as the bacteria and will contribute to the development of multi potent eco-friendly compounds.

Polyurethane/carboxymethylcellulose nanofibers containing Malva sylvestris extract for healing diabetic wounds: Preparation, characterization, in vitro and in vivo studies

In this study, new polyurethane (PU)-based nanofibers wound dressings containing Malva sylvestris extract were prepared and their effect on diabetic wound healing process was evaluated. Different amounts of carboxymethyl cellulose (CMC) were used to improve the absorption ability of wound exudates. The result showed that the usage of 20% w/w CMC in the polymer blend; and producing of nanofibers with an average diameter of 386.5 nm, led to the gradual release of the herbal compound in 85 h and bead-free morphology. Due to the antibacterial activity of wound dressing and wound healing process, the amount of 15% w/w herbal extract was selected as the optimum. For this sample, the fluid absorption was 412.31%. The extract loaded wound dressing samples showed satisfactory effects on Staphylococcus aureus and Escherichia coli bacteria. In vivo wound-healing and histological performance observations indicated that the use of the herbal extract in wound dressing improved wound healing significantly. On day 14, the average healing rate for gauze bandage, PU/CMC, and different amounts of 5, 10, 15 and 20% w/w extract containing wound dressings was 32.1 ± 0.2%, 51.4 ± 0.4%, 71 ± 0.14%, 87.64 ± 1.02%, 95.05 ± 0.24% and 95.11 ± 0.2%, respectively. Compared to the control groups, treatments with extract loaded wound dressings were effective in lowering acute and chronic inflammations. In diabetic rat wounds, collagen deposition and neovascularization were higher in wounds treated with an herbal extract containing wound dressing compared to the wounds treated with a gauze bandage and PU/CMC treated wounds. It can be suggested that this product may be considered as a good dual anti-inflammatory-antimicrobial wound dressing candidate for improving the diabetic wound healing.

Bio-nanoparticle assembly: a potent on-site biolarvicidal agent against mosquito vectors

Background: Vector-borne diseases such as malaria, dengue, yellow fever, encephalitis and filariasis are considered serious human health concerns in the field of medical entomology. Controlling the population of mosquito vectors is one of the best strategies for combating such vector-borne diseases. However, the use of synthetic insecticides for longer periods of time increases mosquito resistance to the insecticides. Recently, the search for new environmentally friendly and efficient insecticides has attracted major attention globally. With the evolution of material sciences, researchers have reported the effective control of such diseases using various sustainable resources. The present investigation demonstrates a potent on-site biolarvicidal agent against different mosquito vectors such as Aedes albopictus, Anopheles stephensi and Culex quinquefasciatus. Methods: Stable and photo-induced colloidal silver nanoparticles were generated via the surface functionalization of the root extract of Cyprus rotundas. Characterizations of the nanoparticles were performed using assorted techniques, such as UV-visible spectroscopy, FTIR spectroscopy, DLS and HRTEM. The bioefficacy of the synthesized nanoparticles was investigated against different species of mosquito larvae through the evaluation of their life history trait studies, fecundity and hatchability rate of the treated larvae. Histopathological and polymerase chain reaction-random amplified polymorphic DNA (RAPD) analyses of the treated larvae were also examined to establish the cellular damage. Results: The synthesized nanoparticles showed remarkable larvicidal activity against mosquito larvae in a very low concentration range (0.001–1.00) mg L⁻¹. The histopathological study confirmed that the present nanoparticles could easily enter the cuticle membrane of mosquito larvae and subsequently obliterate their complete intestinal system. Furthermore, RAPD analysis of the treated larvae could assess the damage of the DNA banding pattern. Conclusion: The present work demonstrates a potent biolarvicidal agent using sustainable bioresources of the aqueous Cyprus rotundas root extract. The results showed that the synthesized nanoparticles were stable under different physiological conditions such as temperature and photo-induced oxidation. The effectiveness of these materials against mosquito larvae was quantified at very low dose concentrations. The present biolarvicidal agent can be considered as an environmentally benign material to control the mosquito vectors with an immense potential for on-site field applications.

The present work demonstrates a potent and stable biolarvicidal agent using sustainable bioresources. The synthesized nanomaterials can control the mosquito vectors at a very low concentration range (0.01–1.00 mg L⁻¹) for on-site field applications.

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

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

Biological Activities of Euphorbia peplus Leaves Ethanolic Extract and the Extract Fabricated Gold Nanoparticles (AuNPs)

Euphorbia peplus leaves extract (EpExt) and gold nanoparticles (AuNPs) phytofabricated with extract (EpExt-AuNPs) were investigated for biological activities. EpExt and EpExt-AuNPs were screened for: (i) anticancer activity against Hela and HepG2 cell lines; (ii) antimicrobial activity; (iii) hemolytic activity; (iv) cytotoxic or stimulatory effects; and (v) insecticidal activity. AuNPs (size 50 nm) were synthesized. (i) EpExt had a stimulatory effect (51.04%) on Hela cells and an inhibitory effect (-12.83%) on HepG2 cells while EpExt-AuNPs showed inhibitory effects (-54.25% and -59.64% on Hela and HepG2 cells respectively). (ii) Antimicrobial activity of EpExt-AuNPs was significantly higher (ranged from 11.67 mm to 14.33 mm) than that of EpExt (ranged from 5.33 mm to 6.33 mm). (iii) Both EpExt and EpExt-AuNPs displayed 100% hemolysis. (iv) A dose-dependent inhibitory effect of EpExt was observed (ranged from -48.5% to -92.1%), which was greater than that of EpExt-AuNPs (ranged from -32.1% to -69.1%) (v) EpExt-AuNPs was more lethal against mosquito larvae with lethal concentration (LC50) value (202.692 ppm) compared to EpExt (1430.590 ppm). In conclusion, EpExt-AuNPs were inhibitory against HepG2 and Hela cells, while EpExt inhibited HepG2 but stimulated Hela cells. EpExt-AuNPs had antimicrobial effects. EpExt showed dose-dependent inhibitory effects on splenic cells. EpExt-AuNPs were lethal against mosquito larvae.

Biological synthesis of metallic nanoparticles (MNPs) by plants and microbes: their cellular uptake, biocompatibility, and biomedical applications

Metallic nanoparticles (MNPs) with their diverse physical and chemical properties have been applied in various biomedical domains. The increasing demand for MNPs has attracted researchers to develop straightforward, inexpensive, simple, and eco-friendly processes for the enhanced production of MNPs. To discover new biomedical applications first requires knowledge of the interactions of MNPs with target cells. This review focuses on plant and microbial synthesis of biological MNPs, their cellular uptake, biocompatibility, any biological consequences such as cytotoxicity, and biomedical applications. We highlighted the involvement of biomolecules in capping and stabilization of MNPs and the effect of physicochemical parameters particularly the pH on the synthesis of MNPs. Recently achieved milestones to understand the role of synthetic biology (SynBiol) in the synthesis of tailored MNPs are also discussed.

Ultra Small, mono dispersed green synthesized silver nanoparticles using aqueous extract of Sida cordifolia plant and investigation of antibacterial activity

The present study is focused on the synthesis of silver nano particles (Ag NPs) using an aqueous extract of the whole plant of Sida cordifolia as a potential bio-reducing agent and assessment of their antibacterial activity. UV-Vis spectroscopy of composed silver colloidal solution displayed surface Plasmon resonance peak at 420 nm. XRD and TEM analysis revealed the morphology as ultra-small, monodispersed spherical nanoparticles with face-centered cubic structure and mean particle size of 3-6 nm. This ultra-small nano size might owe to the slow reaction time and phytochemicals existing in the S. cordifolia extract. The Ag NPs are trailed for antibacterial activity against 5 fish (Aeromonas hydrophila, Pseudomonas fluorescence, Flavobacterium branchiophilum, Edwardsiella tarda and Yersinia rukeri) and 4 human (Escherichia coli, Klebsiella pneumonia, Bacillus subtilis and Staphyloccocus aureus) bacterial pathogens. In all the cases, Ag NPs from Sida cordifolia plant extract manifested noteworthy antibacterial effects on par with positive control i.e.; Gentamicin.

Antibacterial, anticancer and antioxidant potential of silver nanoparticles engineered using Trigonella foenum-graecum seed extract

In this study, the authors report a simple and eco-friendly method for the synthesis of silver nanoparticles (AgNPs) using Trigonella foenum-graecum (TFG) seed extract. They explored several parameters dictating the biosynthesis of TFG-AgNPs such as reaction time, temperature, concentration of AgNO3, and TFG extract amount. Physicochemical characterisation of TFG-AgNPs was done on dynamic light scattering (DLS), field emission electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction and Fourier transform infrared spectroscopy. The size determination studies using DLS revealed of TFG-AgNPs size between 95 and 110 nm. The antibacterial activity was studied against Escherichia coli, Proteus vulgaris, Pseudomonas aeruginosa and Staphylococcus aureus. The biosynthesised TFG-AgNPs showed remarkable anticancer efficacy against skin cancer cell line, A431 and also exhibited significant antioxidant efficacy.

Biophysical characterization of Acacia caesia-fabricated silver nanoparticles: effectiveness on mosquito vectors of public health relevance and impact on non-target aquatic biocontrol agents

Mosquito-borne diseases lead to serious public health concerns in tropical and sub-tropical countries worldwide, due to development of mosquito resistance to synthetic pesticides, non-target effects of pesticides, and socioeconomic reasons. Currently, green nanotechnology is a promising research field, showing a wide range of potential applications in vector control programs. The employ of natural products as reducing agents to fabricate insecticidal nanocomposites is gaining research attention worldwide, due to low costs and high effectiveness. Interestingly, biophysical features of green-synthesized nanoparticles strongly differ when different botanicals are employed for nanosynthesis. In this study, a cheap Acacia caesia leaf extract was employed to fabricate silver nanoparticles (Ag NPs) with ovicidal, larvicidal, and adulticidal toxicity against three mosquito vectors, Anopheles subpictus, Aedes albopictus, and Culex tritaeniorhynchus. Ag NPs were analyzed by various biophysical methods, including spectroscopy (UV-visible spectrophotometry, XRD, FTIR, EDX) and microscopy (SEM, TEM, AFM) techniques. High acute larvicidal potential was observed against larvae of An. subpictus (LC₅₀ = 10.33 μg/ml), Ae. albopictus (LC₅₀ = 11.32 μg/ml), and Cx. tritaeniorhynchus (LC₅₀ = 12.35 μg/ml). Ag NPs completely inhibited egg hatchability on three vectors at 60, 75, and 90 μg/ml, respectively. In adulticidal assays, LD₅₀ values were 18.66, 20.94, and 22.63 μg/ml. If compared to mosquito larvae, Ag NPs were safer to three non-target aquatic biocontrol agents, with LC₅₀ ranging from 684 to 2245 μg/ml. Overall, our study highlights the potential of A. caesia as an abundant and cheap bioresource to fabricate biogenic Ag NPs effective against mosquito young instars and adults, with moderate impact on non-target aquatic biocontrol agents.

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

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

Structural characterization and evaluation of mosquito-larvicidal property of silver nanoparticles synthesized from the seaweed, Turbinaria ornata (Turner) J. Agardh 1848

The silver nanoparticles synthesized from Turbinaria ornata (To-AgNPs) showed spherical with crystalline nature (20-32 nm) was evaluated against fourth instar larvae of three mosquitoes. The maximum activity of To-AgNPs was recorded on Aedes aegypti followed by Anopheles stephensi and Culex quinquefasciatus with the following lethal concentration values (μg/ml): LC50 of 0.738, 1.134, and 1.494; and LC90 of 3.342, 17.982, and 22.475, respectively. The obtained respective values (μg/ml) vis-a-vis aqueous extract (To-AE) were: 2.767 and 40.577; 4.347 and 158.399, and 7.351 and 278.994. The findings revealed that To-AgNPs could form a base for the development of an eco-friendly, low-cost pesticide.

Green Synthesis of Ag/Ag₂O Nanoparticles Using Aqueous Leaf Extract of Eupatorium odoratum and Its Antimicrobial and Mosquito Larvicidal Activities

The health challenges associated with pathogens and ectoparasites highlight the need for effective control approaches. Metal nanoparticles have been proposed as highly effective tools towards combatting different microbial organisms and parasites. The present work reports the antimicrobial and larvicidal potential of biosynthesized Ag/Ag₂O nanoparticles using aqueous leaf extract of Eupatorium odoratum (EO). The constituents of the leaf extract act as both reducing and stabilizing agents. The UV-VIS spectra of the nanoparticles showed surface plasmon resonance. The particle size and shape of the nanoparticles was analysed by transmission electron microscopy (TEM). The larvicidal study was carried out using third and fourth instar Culex quinquefasciatus larvae. The mosquito larvae were exposed to varying concentrations of plant extract (EO) and the synthesized nanoparticles, and their percentage of mortality was accounted for at different time intervals of 12 h and 24 h periods of exposure. The nanoparticles were more lethal against third and fourth instars of Culex quinquefasciatus larvae at the 24 h period of exposure with lower lethal concentration values (LC50 = 95.9 ppm; LC90 = 337.5 ppm) and (LC50 = 166.4 ppm; LC90 = 438.7 ppm) compared to the plant extract (LC50 = 396.8 ppm; LC90 = 716.8 ppm and LC50 = 448.3 ppm; LC90 = 803.9 ppm, respectively). The antimicrobial properties of the nanoparticles were established against different clinically-isolated microbial strains and compared to that of the plant extract (EO) and standard antimicrobial drugs. The nanoparticles were generally more active than the plant extract against the selected microbial organisms. The Gram-negative bacterial strains Escheerichua coli and Salmonella typhi were more susceptible towards the nanoparticles compared to the Gram-positive strains and the fungal organism.

Ipomoea batatas (Convolvulaceae)-mediated synthesis of silver nanoparticles for controlling mosquito vectors of Aedes albopictus, Anopheles stephensi, and Culex quinquefasciatus (Diptera:Culicidae)

We proposed an effective and eco-friendly control of dengue, malaria, and filariasis-causing vectors. We tested Ipomoea batatas leaves-mediated silver nanoparticles (AgNPs) against first to fourth instar larvae and adults of Aedes albopictus, Anopheles stephensi, and Culex quinquefasciatus at different concentrations. The synthesized AgNPs showed broad spectrum of larvicidal and adulticidal effects after 48 h of exposure. The characterization of synthesized AgNPs was done using various spectral and microscopy analyses. The maximum efficacy was observed in synthesized AgNPs against the adult of Ae. albopictus with the LC₅₀ and LC₉₀ values were 10.069 and 15.657 μg/mL, respectively, followed by others.

Novel synthesis of silver nanoparticles using Bauhinia variegata: a recent eco-friendly approach for mosquito control

Mosquito vectors are responsible for transmitting diseases such as malaria, dengue, chikungunya, Japanese encephalitis, dengue, and lymphatic filariasis. The use of synthetic insecticides to control mosquito vectors has caused physiological resistance and adverse environmental effects, in addition to high operational cost. Biosynthesis of silver nanoparticles has been proposed as an alternative to traditional control tools. In the present study, green synthesis of silver nanoparticles (AgNPs) using aqueous leaf extract of Bauhinia variegata by reduction of Ag(+) ions from silver nitrate solution has been investigated. The bioreduced silver nanoparticles were characterized by UV–visible spectrophotometry, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray analysis (EDX), and X-ray diffraction analysis (XRD). Leaf extract and synthesized AgNPs were evaluated against the larvae of Anopheles subpictus, Aedes albopictus, and Culex tritaeniorhynchus. Compared to aqueous extract, synthesized AgNPs showed higher toxicity against An. subpictus, Ae. albopictus, and Cx. tritaeniorhynchus with LC50 and LC90 values of 41.96, 46.16, and 51.92 μg/mL and 82.93, 89.42, and 97.12 μg/mL, respectively. Overall, this study proves that B. variegata is a potential bioresource for stable, reproducible nanoparticle synthesis and may be proposed as an efficient mosquito control agent.

One-pot green synthesis of silver nanocrystals using Hymenodictyon orixense: a cheap and effective tool against malaria, chikungunya and Japanese encephalitis mosquito vectors?

Mosquitoes are important vectors of malaria, dengue, Zika virus and many other parasites and pathogens of public health relevance.