Applications of plant terpenoids in the synthesis of colloidal silver nanoparticles

Rethinking Nanoparticle Synthesis: A Sustainable Approach vs. Traditional Methods

This review portrays a comparison between green protocols and conventional nanoparticle (NP) synthesis strategies, highlighting each method's advantages and limitations. Various top-down and bottom-up methods in NP synthesis are described in detail. The green chemistry principles are emphasized for designing safe processes for nanomaterial synthesis. Among the green biogenic sources plant extracts, vitamins, enzymes, polysaccharides, fungi (Molds and mushrooms), bacteria, yeast, algae, and lichens are discussed. Limitations in the reproducibility of green protocols in terms of availability of raw material, variation in synthetic protocol, and selection of material due to geographical differences are elaborated. Finally, a conclusion is drawn utilizing green chemical principles, & a circular economy strategy to minimize waste generation, offering a promising framework for the synthesis of NPs emphasizing sustainability.

Waste-Derived Caffeine for Green Synthesis of Rhenium Nanoparticles with Enhanced Catalytic Activity in the Hydrogenation of 4-Nitrophenol

Yearly, thousands of tons of wasted coffee grounds are produced according to high coffee consumption. Still, after the coffee brewing, wasted coffee grounds contain some amounts of caffeine (CAF). CAF, in turn, contains multiple O and N chelating atoms in its structure. These have a potential to be reductors for complexes of metals. In this context, within the present study, a set of CAF extracts derived from coffee beans and coffee grounds were obtained and then used for the one-step reduction of ReO4- ions with no additional toxic chemicals. Within this approach, CAF was applied as a secondary, green resource for the synthesis of unique rhenium nanoparticles (ReNPs) containing Re species at 0 and +6 oxidation states. The obtained ReNPs were identified and characterized with the use of X-ray powder diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM). Further, the capping and stabilization of ReNPs by CAF were verified with the aid of Fourier transformation infrared spectroscopy (FT-IR). The so-obtained "green" ReNPs were then used as a homogenous catalyst in the catalytic hydrogenation of 4-nitrophenol (4-NP). This new nanomaterial revealed a superior catalytic activity, leading to the complete reduction of 4-NP to 4-aminophenol within 40-60 min with a first-order rate constant of 0.255 min-1.

Synthesis of metallic nanoparticles using biometabolites: mechanisms and applications

Bio-metabolites have played a crucial role in the recent green synthesis of nanoparticles, resulting in more versatile, safer, and effective nanoparticles. Various primary and secondary metabolites, such as proteins, carbohydrates, lipids, nucleic acids, enzymes, vitamins, organic acids, alkaloids, flavonoids, and terpenes, have demonstrated strong metal reduction and stabilization properties that can be utilized to synthesize nanomaterials and influence their characters. While physical and chemical methods were previously used to synthesize these nanomaterials, their drawbacks, including high energy consumption, elevated cost, lower yield, and the use of toxic chemicals, have led to a shift towards eco-friendly, rapid, and efficient alternatives. Biomolecules act as reducing agents through deprotonation, nucleophilic reactions, transesterification reactions, ligand binding, and chelation mechanisms, which help sequester metal ions into stable metal nanoparticles (NPs). Engineered NPs have potential applications in various fields due to their optical, electronic, and magnetic properties, offering improved performance compared to bulkier counterparts. NPs can be used in medicine, food and agriculture, chemical catalysts, energy harvesting, electronics, etc. This review provides an overview of the role of primary and secondary metabolites in creating effective nanostructures and their potential applications.

Biomimetic synthesis of nanoparticles: A comprehensive review on green synthesis of nanoparticles with a focus on Prosopis farcta plant extracts and biomedical applications

The synthesis of nanoparticles (NPs) using environmentally friendly methods has garnered significant attention in response to concerns about the environmental impact of various nanomaterial manufacturing techniques. To address this issue, natural resources like extracts from plants, fungi, and bacteria are employed as a green alternative for nanoparticle synthesis. Plant extracts, which contain active components such as terpenoids, alkaloids, phenols, tannins, and vitamins, operate as coating and reducing agents. Bacteria and fungi, on the other hand, rely on internal enzymes, sugar molecules, membrane proteins, nicotinamide adenine dinucleotide (NADH), and nicotinamide adenine dinucleotide phosphate (NADPH) dependent enzymes to play critical roles as reducing agents. This review collects recent advancements in biomimetic methods for nanoparticle synthesis, critically discussing the preparation approaches, the type of particles obtained, and their envisaged applications. A specific focus is given on using Prosopis fractal plant extracts to synthesize nanoparticles tailored for biomedical applications. The applications of this plant and its role in the biomimetic manufacturing of nanoparticles have not been reported yet, making this review a pioneering and valuable contribution to the field.

Antibacterial Efficacy and Characterization of Silver Nanoparticles Synthesized via Methanolic Extract of Fomes fomentarius L. Fr

Green synthesis employs environmentally friendly, biodegradable substances for the production of nanomaterials. This study aims to develop an innovative method for synthesizing silver nanoparticles (AgNPs) using a methanolic extract of Fomes fomentarius L. Fr. as the reducing agent and to assess the potential antibacterial properties of the resulting nanoparticles. The successful synthesis of AgNPs was confirmed through characterization techniques such as UV-visible (UV-Vis) spectrophotometry, Fourier-transform infrared spectroscopy (FT-IR), and powder X-ray diffraction (PXRD). The UV-Vis analysis revealed an absorption peak at 423 nm, while FT-IR identified key phytochemical compounds involved in the reduction process. PXRD analysis indicated a face-centered cubic (fcc) structure with prominent peaks observed at 2θ = 38°, 44.6°, 64.6°, and 78°, confirming the crystalline nature of the AgNPs, with a crystallite diameter of approximately 24 nm, consistent with TEM analysis. The synthesized AgNPs demonstrated significant antibacterial activity, particularly against S. aureus, with higher efficacy against gram-positive bacteria.

Development of phytosterol-loaded silver nanoparticles for ameliorating haemorrhoidal complications via the AMPK pathway-a mechanistic approach

The aim of the current study was to synthesize silver nanoparticles (PLSNPs) using green technology by means of phytosterol-enriched fractions fromBlumea laceraextracts (EAF) and evaluate their toxicological and anti-haemorrhoidal potential. The average size of the synthesized particles was found to be 85.64 nm by scanning electron microscopy and transmission electron microscopy. Energy dispersive spectroscopy showed the elemental composition of PLSNPs to be 12.59% carbon and 87.41% silver, indicating the capping of phytochemicals on the PLSNPs. The PLSNPs were also standardized for total phytosterol content using chemical methods and high-perfromance liquid chromatography. The PLSNPs were found to be safe up to 1000 mg kg-1as no toxicity was observed in the acute and sub-acute toxicity studies performed as per OECD guidelines. After the induction of haemorrhoids, experimental animals were treated with different doses of EAF, PLSNPs and a standard drug (Pilex) for 7 d, and on the eighth day the ameliorative potential was assessed by evaluating the haemorrhoidal (inflammatory severity index, recto-anal coefficient) and biochemical (tumour necrosis factor-alpha and interleukin-6) parameters and histology of the recto-anal tissue. The results showed that treatment with PLSNPs and Pilex significantly (p< 0.05) reduced haemorrhoidal and biochemical parameters. This was further supported by restoration of altered antioxidant status. Further, a marked reduction in the inflammatory zones along with minimal dilated blood vessels was observed in the histopathological study. The results of molecular docking studies also confirmed the amelioration of haemorrhoids via AMP-activated protein kinase (AMPK)-mediated reduction of inflammation and endothelin B receptor modification by PLSNPs. In conclusion, PLSNPs could be a good alternative for the management of haemorrhoids.

Silver nanoparticles biogenically synthesised using Maclurodendron porteri extract and their bioactivities

Silver nanoparticle is widely used in various field including medical, cosmetic, food and industrial purposes due to their unique properties in electrical conductivity, thermal, and biological activities. In the medical field, silver nanoparticles (AgNPs) have been reported to have strong antimicrobial and cytotoxic activities. This study aimed to synthesize and characterize silver nanoparticles (AgNPs) using Maclurodendron porteri (MP) extract and to evaluate the antimicrobial and cytotoxic activities of the synthesised MP-AgNPs. Green method of Ultrasound Assisted Extraction (UAE) was used to extract the leaves of M. porter. Liquid Chromatography -Mass Spectrometry/Quadrupole time-of-flight (LC-MS/QTOF) was used to identify the compounds in the leaf extract of M. porteri. Characterisation of the synthesised nanoparticles involved ultraviolet-visible (UV-Vis), Fourier Transform Infrared (FTIR), scanning electromagnetic microscopy (SEM), Zeta potential Analyzer and Particle Size Analyzer. The cytotoxic assay was conducted on MCF-7 and Caco-2 cell lines by MTT assay. Antimicrobial activity was tested on Gram-negative and Gram-positive bacteria using the disc diffusion method. Based on LC-MS/QTOF analysis, 430 compounds were found. The identified major compounds consist of amino acids, polyphenols, steroids, terpenoids and heterocyclic compounds which possibly act as reducing agents. 1 mM, 5 mM and 10 mM of silver nitrate solution were mixed with the leaf extract to form silver nanoparticles. 1.2 mg/ml of MP-AgNPs were found to have antibacterial activity against B. subtilis, S. aureus, E. coli, and P. aeruginosa with inhibitory zones of 8.0 ± 0.36 mm, 8.5 ± 0.45 mm, 7.5 ± 0.36 mm, and 9.0 ± 0.40 mm respectively. MP-AgNPs showed no cytotoxic activity against Caco-2 and MCF-7 cells. In conclusion, the presence of major amine compounds such as 10,11-dihydro-10,11-dihydroxyprotriptyline and harderoporphyrin in the extract facilitated the synthesis of AgNPs and the nanoparticle showed weak bioactivities in the assay conducted.

Nanoengineered chitosan functionalized titanium dioxide biohybrids for bacterial infections and cancer therapy

Nanoengineered chitosan functionalized titanium dioxide biohybrids (CTiO2@NPs) were prepared with Amomum subulatum Roxb extract via one-pot green method and assessed by UV-Vis spectroscopy, XRD, SEM and EDAX analyses. As revealed by XRD pattern, the nanohybrids exhibits a rutile TiO2 crystallites around 45 nm in size. The emergence of the Ti-O-Ti bond is identified by observing a peak between 400 and 800 cm-1. A wide bandgap (4.8 eV) has been observed in CTiO2@NPs, due to the quantum confinement effects and the oxygen vacancies reveal the intriguing potential of developed nanohybrids for various applications. Surface flaws were identified by observing an emission band at 382, 437, 482, 517, and 556 nm. They also exhibit better antibacterial performances using well diffusion method against Staphylococcus aureus, Bacillus substilis, Klebsiella pneumonia, and Escherichia coli. CTiO2@NPs were discovered to have free radical scavenging activity on DPPH analysis and exhibit IC50 value as 95.80 μg/mL and standard (Vitamin C) IC50 is 87.62 μg/mL. CTiO2@NPs exhibited better anticancer properties against the osteosarcoma (MG-63) cell line. All these findings suggest that there is a forum for further useful therapeutic applications. Therefore, we claim that nano-engineered carbohydrated TiO2 phytohybrid is a promising solution for bacterial infections and bone cancer.

Green Synthesis of Narrow-Size Silver Nanoparticles Using Ginkgo biloba Leaves: Condition Optimization, Characterization, and Antibacterial and Cytotoxic Activities

Natural products derived from medicinal plants offer convenience and therapeutic potential and have inspired the development of antimicrobial agents. Thus, it is worth exploring the combination of nanotechnology and natural products. In this study, silver nanoparticles (AgNPs) were synthesized from the leaf extract of Ginkgo biloba (Gb), having abundant flavonoid compounds. The reaction conditions and the colloidal stability were assessed using ultraviolet-visible spectroscopy. X-ray diffraction, transmission electron microscopy, and Fourier transform infrared spectroscopy (FTIR) were used to characterize the AgNPs. AgNPs exhibited a spherical morphology, uniform dispersion, and diameter ranging from ~8 to 9 nm. The FTIR data indicated that phytoconstituents, such as polyphenols, flavonoids, and terpenoids, could potentially serve as reducing and capping agents. The antibacterial activity of the synthesized AgNPs was assessed using broth dilution and agar well diffusion assays. The results demonstrate antibacterial effects against both Gram-positive and Gram-negative strains at low AgNP concentrations. The cytotoxicity of AgNPs was examined in vitro using the CCK-8 method, which showed that low concentrations of AgNPs are noncytotoxic to normal cells and promote cell growth. In conclusion, an environmentally friendly approach for synthesizing AgNPs from Gb leaves yielded antibacterial AgNPs with minimal toxicity, holding promise for future applications in the field of biomedicine.

Low-Cost Plant-Based Metal and Metal Oxide Nanoparticle Synthesis and Their Use in Optical and Electrochemical (Bio)Sensors

Technological progress has led to the development of analytical tools that promise a huge socio-economic impact on our daily lives and an improved quality of life for all. The use of plant extract synthesized nanoparticles in the development and fabrication of optical or electrochemical (bio)sensors presents major advantages. Besides their low-cost fabrication and scalability, these nanoparticles may have a dual role, serving as a transducer component and as a recognition element, the latter requiring their functionalization with specific components. Different approaches, such as surface modification techniques to facilitate precise biomolecule attachment, thereby augmenting recognition capabilities, or fine tuning functional groups on nanoparticle surfaces are preferred for ensuring stable biomolecule conjugation while preserving bioactivity. Size optimization, maximizing surface area, and tailored nanoparticle shapes increase the potential for robust interactions and enhance the transduction. This article specifically aims to illustrate the adaptability and effectiveness of these biosensing platforms in identifying precise biological targets along with their far-reaching implications across various domains, spanning healthcare diagnostics, environmental monitoring, and diverse bioanalytical fields. By exploring these applications, the article highlights the significance of prioritizing the use of natural resources for nanoparticle synthesis. This emphasis aligns with the worldwide goal of envisioning sustainable and customized biosensing solutions, emphasizing heightened sensitivity and selectivity.

Efficient green silver nanoparticles-antibiotic combinations against antibiotic-resistant bacteria

Antibiotic-resistant bacterial strains and the consequent surge in infections caused by them have become major public health concerns. Silver nanoparticles (AgNPs) exhibit antibacterial properties and have wide applications in biomedical sciences. In this study, AgNPs were synthesized in the presence of antibiotics: Ceftazidime (Cft), Cefotaxime (Cef), Ceftriaxone (Cfx), and Cefepime (Cpm), along with the extract of Mentha longifolia. Mentha longifolia-based AgNPs were kept as the control for all experiments. The associated metabolites, structural properties, surface charges, and antibacterial activity of the AgNPs were also evaluated. Overall, a blue-shift of SPR peaks was observed for control AgNPs (λmax = 421 nm, 422 nm, 426 nm, and 406 nm for Cft-AgNPs, Cef-AgNPs, Cfx-AgNPs, and Cpm-AgNPs, respectively), compared to the control (λmax = 438 nm). Fourier-transform infrared spectroscopy showed that antibiotic-based AgNPs had distinct peaks that corresponded to the respective antibiotics, which were not observed in the control. XRD analysis showed that there were observed changes in crystallinity in antibiotic-based AgNPs compared to the control. TEM images revealed that all samples had spherical nanoparticles with different sizes and distributions compared to the control. The Zeta potential for extract-based AgNPs was - 33.6 mV, compared to -19.6 mV for Cft-AgNPs, -2 mV for Cef-AgNPs, -21.1 mV for Cfx-AgNPs, and - 24.2 mV for Cpm-AgNPs. The increase in the PDI value for antibiotic-based AgNPs also showed a highly polydisperse distribution. However, the antibiotic-AgNPs conjugates showed significantly higher activity against pathogenic bacteria. The addition of antibiotics to AgNPs brought significant changes in structural properties and antibacterial activities.

Revisiting the Green Synthesis of Nanoparticles: Uncovering Influences of Plant Extracts as Reducing Agents for Enhanced Synthesis Efficiency and Its Biomedical Applications

Background

Conventional nanoparticle synthesis methods involve harsh conditions, high costs, and environmental pollution. In this context, researchers are actively searching for sustainable, eco-friendly alternatives to conventional chemical synthesis methods. This has led to the development of green synthesis procedures among which the exploration of the plant-mediated synthesis of nanoparticles experienced a great development. Especially, because plant extracts can work as reducing and stabilizing agents. This opens up new possibilities for cost-effective, environmentally-friendly nanoparticle synthesis with enhanced size uniformity and stability. Moreover, bio-inspired nanoparticles derived from plants exhibit intriguing pharmacological properties, making them highly promising for use in medical applications due to their biocompatibility and nano-dimension.

Objective

This study investigates the role of specific phytochemicals, such as phenolic compounds, terpenoids, and proteins, in plant-mediated nanoparticle synthesis together with their influence on particle size, stability, and properties. Additionally, we highlight the potential applications of these bio-derived nanoparticles, particularly with regard to drug delivery, disease management, agriculture, bioremediation, and application in other industries.

Methodology

Extensive research on scientific databases identified green synthesis methods, specifically plant-mediated synthesis, with a focus on understanding the contributions of phytochemicals like phenolic compounds, terpenoids, and proteins. The database search covered the field's development over the past 15 years.

Results

Insights gained from this exploration highlight plant-mediated green synthesis for cost-effective nanoparticle production with significant pharmacological properties. Utilizing renewable biological resources and controlling nanoparticle characteristics through biomolecule interactions offer promising avenues for future research and applications.

Conclusion

This review delves into the scientific intricacies of plant-mediated synthesis of nanoparticles, highlighting the advantages of this approach over the traditional chemical synthesis methods. The study showcases the immense potential of green synthesis for medical and other applications, aiming to inspire further research in this exciting area and promote a more sustainable future.

Chemical background of silver nanoparticles interfering with mammalian copper metabolism

The rapidly increasing application of silver nanoparticles (AgNPs) boosts their release into the environment, which raises a reasonable alarm for ecologists and health specialists. This is manifested as increased research devoted to the influence of AgNPs on physiological and cellular processes in various model systems, including mammals. The topic of the present paper is the ability of silver to interfere with copper metabolism, the potential health effects of this interference, and the danger of low silver concentrations to humans. The chemical properties of ionic and nanoparticle silver, supporting the possibility of silver release by AgNPs in extracellular and intracellular compartments of mammals, are discussed. The possibility of justified use of silver for the treatment of some severe diseases, including tumors and viral infections, based on the specific molecular mechanisms of the decrease in copper status by silver ions released from AgNPs is also discussed.

Green synthesis and antimicrobial mechanism of nanoparticles: applications in agricultural and agrifood safety

The growing demand for food and its safety are a challenge for agriculture and agrifood. This has led to the incorporation of alternatives such as organic agriculture, the use of biocontrollers, the development of transgenic plants resistant to pathogens and the incorporation of nanotechnology. In this sense, agrochemicals based on nanoparticles (NPs) have been developed. Recently, the green synthesis of NPs has grown rapidly and, for this reason, molecules, microorganisms, fungi and plants are used. Synthesis from plant extracts offers a broad spectrum and, despite the fact that NPs are usually dispersed in size and shape, extensive antimicrobial effectiveness has been demonstrated at nanomolar concentrations. It has been shown that the mechanism of action can be through the dissipation of the driving force of the protons, the alteration of cellular permeability, the formation of bonds with the thiol group of the proteins, the generation of reactive species of oxygen, and the hyperoxidation of DNA, RNA and even the cell membrane. To improve the efficiency of NPs, modifications have been made such as coating with other metals, the addition of antibiotics, detergents and surfactants, as well as the acidification of the solution. Consequently, NPs are considered as a promising method for achieving safety in the agricultural and agrifood area. However, it is necessary to investigate the side effects of NPs, when applied in agroecological systems, on the textural, nutriment and sensory properties of food, as well as the impact on human health. © 2022 Society of Chemical Industry.

Green synthesis of AgNPs using Delonix regia bark for potential catalytic and antioxidant applications

Nanoparticle synthesis from plant resources has recently gained significant impact due to its low cost, simple equipment requirements, and ease of availability. In this work, DR-AgNPs were synthesized using bark extract of Delonix regia (D. regia) plant under microwave irradiation. The formation of DR-AgNPs has been confirmed with UV-Vis, XRD, FTIR, FESEM, HRTEM, EDS, DLS, and zeta potential analysis. Catalytic and antioxidant activities were tested on synthesized spherical nanoparticles with a size range of 10-48 nm. The effects of pH and catalyst dosage on the methylene blue (MB) dye degradation were carried out. It was observed from the treatment results that 95% MB dye degradation efficiency was achieved within 4 min with a degradation rate constant of 0.772 min^-1 . The synthesized nanoparticles showed a strong antioxidant property when analyzed by a 2,2-Diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assay. The calculated IC₅₀ value for DR-AgNPs was 37.1 ± 0.12 μg mL^-1 . Therefore, DR-AgNPs are excellent in both catalytic and antioxidant activities when compared to previously reported works. HIGHLIGHTS: Green synthesis of silver nanoparticles (DR-AgNPs) using Delonix regia bark extract. The catalytic activity of DR-AgNPs is remarkable against Methylene Blue. DR-AgNPs also have a strong DPPH radical antioxidant effect. Short degradation time, high degradation rate constant, and a good scavenging activity are key features of this study compared to previously reported works.

One-Step Phytofabrication Method of Silver and Gold Nanoparticles Using Haloxylon salicornicum for Anticancer, Antimicrobial, and Antioxidant Activities

Among various routes of metallic nanoparticle (NPs) fabrication, phytosynthesis has significant advantages over other conventional approaches. Plant-mediated synthesis of NPs is a fast, one-step, ecobenign, and inexpensive method with high scalability. Herein, silver (Ag) and gold (Au)-NPs were extracellularly synthesized using aqueous Haloxylon salicornicum (H@Ag-, H@Au-NPs) leaf extracts. GC-MS was performed to analyze the chemical compositions of H. salicornicum extract. H@Ag- and H@Au-NPs were characterized via UV-Vis spectroscopy, Fourier transform infrared spectroscopy, X-ray diffraction, transmission and scanning electron microscopy, and Zetasizer. H@Ag- and H@Au-NPs have surface plasmon resonance at 435.5 and 530.3 nm, respectively. FTIR and GC-MS data suggest that secondary plant metabolites and hydrocarbons might be responsible for the reduction and stabilization of NPs. XRD demonstrated that both NPs have a crystalline nature. H@Ag-NPs have a uniform spherical shape, whereas H@Au-NPs are spherical with few oval and triangular shapes, and their average nanosizes were 19.1 ± 0.8 and 8.1 ± 0.3 nm, respectively. Hydrodynamic diameters of H@Ag-NPs and H@Au-NPs were 184.7 nm, 56.4, and 295.4 nm, and their potential charges were -24.0 and -24.4 mV, respectively. The inhibitory activity of 500 µg/mL H@Ag- and H@Au-NPs was tested against Sw480, Sw620, HCT-116, and Caco-2 colon cancer cell lines and two normal cell lines, including HFs and Vero. H@Ag-NPs revealed potent anticancer activity against all cancer cells at low concentrations. Sw480 was the most sensitive cell to H@Ag-NPs, whereas Sw620 was the least permeable one. These findings suggested that the antiproliferative activity of H@Ag-NPs is cell-response-dependent and may be influenced by a variety of factors, including the cellular metabolic state, which influences cellular charge and interactions with charged NPs. Although H@Au-NPs were smaller, their reactivity against cancer cells was weak, suggesting that the chemical properties, metal structure, quantity and chemistry of the functional groups on the NP surface may influence their reactivity. The biocidal activity of 1 mg/mL H@Ag- and H@Au-NPs against Staphylococcus aureus, Bacillus cereus, Escherichia coli and Klebsiella pneumoniae was assessed. H@Ag-NPs showed biocidal activity against Gram-positive bacteria compared to Gram-negative bacteria, whereas H@Au-NPs showed no inhibitory activity. FRAP and DPPH assays were used to determine the scavenging activity of the plant extracts and both NPs. H@Ag-NPs (1 mg/mL) had the greatest scavenging activity compared to tested drugs. These findings suggest that H@Ag-NPs are potent anticancer, antibacterial, and antioxidant agents, while H@Au-NPs may be used as a drug vehicle for pharmaceutical applications.

Dose-dependent biological toxicity of green synthesized silver nanoparticles in rat's brain

Metal nanoparticles, in general, and silver nanoparticles (AgNPs), in particular, have been the focus of numerous studies over the last two decades. Recently, the green synthesis of metal nanoparticles has been favored over chemical synthesis due to its low toxicity and easy preparation. The present study aims to investigate the dose-dependent toxicity of green synthesized AgNPs on rats' brains. Thirty-four Wistar male rats were divided into four groups. The first, second, and third groups were administered for 14 days with three different doses (0.5, 5, and 10 mg/kg) of AgNPs, respectively. The fourth group, which served as a control group, was given normal saline for the same period. The toxicity of the green synthesized AgNPs on the cortical and hippocampal levels of the oxidative stress markers (MDA, NO, and GSH) as well as the activity of acetylcholinesterase (AchE) and the monoamine neurotransmitters (DA, NE, and 5H-T) were investigated. AgNPs showed minimal oxidative stress in the cortex and hippocampus for the administered doses. However, AgNPs showed an inhibitory effect on AchE activity in a dose-dependent manner and a decrease in the 5H-T and NE levels. The green synthesized AgNPs showed an ultrastructural change in the cellular membranes of the neurons. The green synthesis of AgNPs has reduced their cytotoxic oxidative effects due to their capping with biologically compatible and boosting molecules such as flavonoids. However, another neurotoxicity was observed in a dose-dependent manner.

Formulation and characterisation of Azadirachta indica nanobiopesticides for ecofriendly control of wheat pest Tribolium castaneum and Rhyzopertha dominica

This study aimed to formulate the green, sustainable, and ecofriendly nanobiopesticides of Azadirachta indica with enhanced pest control efficacy. Nanoprecipitation method was used for the development of nanobiopesticides. Optimisation was done by response surface methodology. Nanoformulations were characterised by zetasizer, scanning electron microscopy, energy dispersive x-ray spectroscopy, atomic force microscopy, and Fourier transform infrared spectroscopy. Pesticidal potential of nanosuspensions was evaluated by insecticide impregnated filter paper method. Optimised nanobiopesticide showed an average particle size of 275.8 ± 0.95 nm, polydispersity index (PDI) 0.351 ± 0.002, and zeta potential of -33 ± 0.90 mV. Nanobiopesticides exhibited significantly higher mortality rates of 86.81 ± 3.04 and 84.97 ± 2.83% against Tribolium castaneum and Ryzopertha dominica, respectively, as compared to their crude extract. Minor change in particle size from 275.8 ± 0.95 to 298.8 ± 1.00 nm and PDI from 0.351 ± 0.002 to 0.445 ± 0.02 were observed after 3 months of storage at 4 °C. Pesticidal efficacy of A. indica was significantly enhanced by the formulation of its nanobiopesticides.

Bioinspired Green Synthesis of Silver Nanoparticles Using Three Plant Extracts and Their Antibacterial Activity against Rice Bacterial Leaf Blight Pathogen Xanthomonas oryzae pv. oryzae

Rice bacterial leaf blight caused by Xanthomonas oryzae pv. oryzae (Xoo) is responsible for a significant reduction in rice production. Due to the small impact on the environment, biogenic nanomaterials are regarded as a new type of antibacterial agent. In this research, three colloids of silver nanoparticles (AgNPs) were synthesized with different biological materials such as Arctium lappa fruit, Solanum melongena leaves, and Taraxacum mongolicum leaves, and called Al-AgNPs, Sm-AgNPs and Tm-AgNPs, respectively. The appearance of brown colloids and the UV-Visible spectroscopy analysis proved the successful synthesis of the three colloids of AgNPs. Moreover, FTIR and XRD analysis revealed the formation of AgNPs structure. The SEM and TEM analysis indicated that the average diameters of the three synthesized spherical AgNPs were 20.18 nm, 21.00 nm, and 40.08 nm, respectively. The three botanical AgNPs had the strongest bacteriostatic against Xoo strain C2 at 20 μg/mL with the inhibition zone of 16.5 mm, 14.5 mm, and 12.4 mm, while bacterial numbers in a liquid broth (measured by OD600) decreased by 72.10%, 68.19%, and 65.60%, respectively. Results showed that the three AgNPs could inhibit biofilm formation and swarming motility of Xoo. The ultrastructural observation showed that Al-AgNPs adhered to the surface of bacteria and broke the bacteria. Overall, the three synthetic AgNPs could be used to inhibit the pathogen Xoo of rice bacterial leaf blight.

Retrospective analysis of the key molecules involved in the green synthesis of nanoparticles

Emerging nanotechnology leads to success in synthesizing and applying nanoparticles (NPs) using the green-chemistry approach. NPs synthesized using naturally derived materials are a potential alternative to chemical and physical methods because they are simple, cost-effective, eco-friendly, and lower the possibility of hazardous residues being released into the environment. Furthermore, NPs synthesized using the green synthesis approach are stable and biocompatible. However, because natural extracts contain a diverse spectrum of bioactive components, it is difficult to pinpoint the specific component involved in NP formation. Furthermore, the bioactive component contained in the extract changes based on a number of environmental factors; therefore, several studies began with the synthesis of NPs using a pure compound isolated from diverse natural sources. Hence, the present review paper makes an effort to retrospectively analyze the key compounds of the extracts which are responsible for the synthesis of the NPs. The analysis was carried out based on the physicochemical characteristics and biological activities of NPs synthesized from either the extract or the pure compounds. These pure-compound-based NPs were studied for their antimicrobial, antibiofilm, anti-inflammatory, anticancer, and antioxidant properties. In addition, the present review also describes progress in the study of pure compound-based numerous biological activities and the underlying mechanisms of action.

Biosynthesized silver nanoparticles using Polygonatum geminiflorum efficiently control fusarium wilt disease of tomato

Nanomaterials are gaining tremendous potential as emerging antimicrobials in the quest to find resistance-free alternatives of chemical pesticides. In this study, stable silver nanoparticles were synthesized using the aqueous extract of medicinal plant species Polygonatum geminiflorum , and their morphological features were evaluated by transmission electron microscopy, X-ray diffraction spectroscopy and energy dispersive X-ray analysis. In vitro Antifungal activity of the synthesized silver nanoparticles (AgNPs) and P. geminiflorum extract (PE) either alone or in combination (PE-AgNPs) against Fusarium oxysporum was evaluated using disc-diffusion and well-diffusion methods. In planta assay of the same treatments against Fusarium wilt diseases of tomato was evaluated by foliar spray method. Moreover, plant extract was evaluated for the quantitative investigation of antioxidant activity, phenolics and flavonoids by spectroscopic and HPLC techniques. Phytochemical analysis indicated the presence of total phenolic and flavonoid contents as 48.32 mg ± 1.54 mg GAE/g and 57.08 mg ± 1.36 mg QE/g, respectively. The DPPH radical scavenging of leaf extract was found to be 88.23% ± 0.87%. Besides, the HPLC phenolic profile showed the presence of 15 bioactive phenolic compounds. Characterization of nanoparticles revealed the size ranging from 8 nm to 34 nm with average crystallite size of 27 nm. The FTIR analysis revealed important functional groups that were responsible for the reduction and stabilization of AgNPs. In the in vitro assays, 100 μg/ml of AgNPs and AgNPs-PE strongly inhibited Fusarium oxysporum. The same treatments tested against Fusarium sprayed on tomato plants in controlled environment exhibited nearly 100% plant survival with no observable phytotoxicity. These finding provide a simple baseline to control Fusarium wilt using silver nano bio-control agents without affecting the crop health.

Comparing the Anticancer Activities of Green-Synthesized Ginsenoside and Transformed Ginsenoside Nanoconjugates (Ag, Au, and Pt)

Aim: To assess the anticancer activity of nanoparticles synthesized via a green method using American ginseng (AG). Methods: Stem-leaf saponins from AG (SAG) and heat-transformed stem-leaf saponins from AG (TSAG) were used to synthesize different SAG nanoparticles (SAG-NPs) and TSAG nanoparticles (TSAG-NPs). The NPs were characterized, and their anticancer activity was assessed in vitro. Results: The NPs, which differed in size (16.69 nm∼253.8 nm), were spherical or polyhedral with a low PDI and good stability. The TSAG-NPs inhibited cancer cells by inhibiting proliferation, promoting cancer cell apoptosis and directly leading cancer cells to necrosis. The small cell lung cancer cell line (SCLC) NCI-H446 was the most sensitive to the TSAG-AgNPs, with an IC50 value of 20.71±2.38 μg/mL, and the TSAG-AgNPs inhibited invasiveness and reduced the risk of metastasis. Conclusion: TSAG-AgNPs, selected from many SAG-NPs and TSAG-NPs, are sensitive to SCLC and provide a new approach to the currently limited treatment.

Green synthesis of silver nanoparticles through oil: Promoting full-thickness cutaneous wound healing in methicillin-resistant Staphylococcus aureus infections

Due to the emergence of multi-drug resistant microorganisms, the development and discovery of alternative eco-friendly antimicrobial agents have become a top priority. In this study, a simple, novel, and valid green method was developed to synthesize Litsea cubeba essential oil-silver nanoparticles (Lceo-AgNPs) using Lceo as a reducing and capping agent. The maximum UV absorbance of Lceo-AgNPs appeared at 423 nm and the size was 5-15 nm through transmission electron microscopy result. The results of Fourier transform infrared and DLS showed that Lceo provided sufficient chemical bonds for Lceo-AgNPs to reinforce its stability and dispersion. The in vitro antibacterial effects of Lceo-AgNPs against microbial susceptible multidrug-resistant Escherichia coli (E. coli) and methicillin-resistant Staphylococcus aureus (MRSA) were determined. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of Lceo-AgNPs against E. coli were 25 and 50 μg/ml. The MIC and MBC of Lceo-AgNPs against MRSA were 50 and 100 μg/ml, respectively. The results of scanning electron microscopy showed that the amount of bacteria obviously decreased and the bacteria cells were destroyed by Lceo-AgNPs. In vivo research disclosed significant wound healing and re-epithelialization effects in the Lceo-AgNPs group compared with the self-healing group and the healing activity was better than in the sulfadiazine silver group. In this experiment, Lceo-AgNPs has been shown to have effects on killing multidrug-resistant bacteria and promoting wound healing. This study suggested Lceo-AgNPs as an excellent new-type drug for wound treatment infected with multidrug-resistant bacteria, and now expects to proceed with clinical research.

Recent advances on botanical biosynthesis of nanoparticles for catalytic, water treatment and agricultural applications: A review

Green synthesis of nanoparticles using plant extracts minimizes the usage of toxic chemicals or energy. Here, we concentrate on the green synthesis of nanoparticles using natural compounds from plant extracts and their applications in catalysis, water treatment and agriculture. Polyphenols, flavonoid, rutin, quercetin, myricetin, kaempferol, coumarin, and gallic acid in the plant extracts engage in the reduction and stabilization of green nanoparticles. Ten types of nanoparticles involving Ag, Au, Cu, Pt, CuO, ZnO, MgO, TiO₂, Fe₃O₄, and ZrO₂ with emphasis on their formation mechanism are illuminated. We find that green nanoparticles serve as excellent, and recyclable catalysts for reduction of nitrophenols and synthesis of organic compounds with high yields of 83-100% and at least 5 recycles. Many emerging pollutants such as synthetic dyes, antibiotics, heavy metal and oils are effectively mitigated (90-100%) using green nanoparticles. In agriculture, green nanoparticles efficiently immobilize toxic compounds in soil. They are also sufficient nanopesticides to kill harmful larvae, and nanoinsecticides against dangerous vectors of pathogens. As potential nanofertilizers and nanoagrochemicals, green nanoparticles will open a revolution in green agriculture for sustainable development.

Photocatalytic and antibacterial activities of green synthesized Ag doped MgO nanocomposites towards environmental sustainability

The utilization of MgO nanoparticles (NPs) for Photocatalytic and antimicrobial activities has gained lots of attention in recent years. Since silver is an expensive material, it's of interest to check that doping of very small concentration of silver will increase the pollutant degradation efficiency of composites. Here Aloe Vera plant extract was used for synthesis of MgO, Ag NPs and Ag/MgO-nanocomposites (NCs). Green synthesized NPs and NCs were confirmed by using different techniques like UV-Vis, BET, TGA, FTIR, PL, XRD (optical, functional, Thermal, Structural) EDX, TEM, SEM, XPS, EIS and EPR (morphological, elemental, photoelectrical and ROS) studies respectively. Then NPs and NCs were applied for the photocatalytic activity of methylene blue (MB), phenol and antimicrobial studies of E. coli bacteria. Ag/MgO-NCs showed 90.18% dye and 80.67% phenol degradation in 120 min which killed E. Coli pathogenic bacteria in 25 min under solar light irradiations. In disk diffusion methods, it inactivates 24 mm area of bacterial cell growth. Thus, among these green synthesized NPs and NCs, Ag/MgO-NCs exhibited enhanced photocatalytic and antimicrobial activities.

Green Synthesis of Silver Nanoparticles Using Euphorbia wallichii Leaf Extract: Its Antibacterial Action against Citrus Canker Causal Agent and Antioxidant Potential

Biologically synthesized silver nanoparticles are emerging as attractive alternatives to chemical pesticides due to the ease of their synthesis, safety and antimicrobial activities in lower possible concentrations. In the present study, we have synthesized silver nanoparticles (AgNPs) using the aqueous extract of the medicinal plant Euphorbia wallichii and tested them against the plant pathogenic bacterium Xanthomonas axonopodis, the causative agent of citrus canker, via an in vitro experiment. The synthesized silver nanoparticles were characterized by techniques such as UV-Vis spectroscopy, Fourier transform infrared spectroscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction analysis and transmission electron microscopy. Moreover, the plant species were investigated for phenolics, flavonoids and antioxidant activity. The antioxidant potential of the extract was determined against a DPPH radical. The extract was also evaluated for phenolic compounds using the HPLC technique. The results confirmed the synthesis of centered cubic, spherical-shaped and crystalline nanoparticles by employing standard characterization techniques. A qualitative and quantitative phytochemical analysis revealed the presence of phenolics (41.52 mg GAE/g), flavonoids (14.2 mg QE/g) and other metabolites of medicinal importance. Different concentrations (1000 µg/mL to 15.62 µg/mL—2 fold dilutions) of AgNPs and plant extract (PE) alone, and both in combination (AgNPs-PE), exhibited a differential inhibition of X. axanopodis in a high throughput antibacterial assay. Overall, AgNPs-PE was superior in terms of displaying significant antibacterial activity, followed by AgNPs alone. An appreciable antioxidant potential was recorded as well. The observed antibacterial and antioxidant potential may be attributed to eight phenolic compounds identified in the extract. The Euphorbia wallichii leaf-extract-induced synthesized AgNPs exhibited strong antibacterial activity against X. axanopodis, which could be exploited as effective alternative preparations against citrus canker in planta in a controlled environment. In addition, as a good source of phenolic compounds, the plant could be further exploited for potent antioxidants.

Green Synthesis of Silver Nanoparticles (AgNPs), Structural Characterization, and their Antibacterial Potential

Background

In the field of nanotechnology, the metallic nanoparticles are of remarkable interest because of their unique electronic, magnetic, chemical, and mechanical properties.

Purpose:

In the present work, silver nanoparticles (AgNPs) were synthesized using bio-reduction method.

Research Design:

Silver nitrate was used as metallic precursor and the extract of Moringa oleifera leaves with different concentrations was used as reducing as well capping agent. The extract exhibited strong potential in rapid reduction of silver ions for the synthesis of silver nanoparticles. The synthesized silver nanoparticles were characterized by UV-visible spectroscopy, X-ray diffraction (XRD), and scanning electron microscopy (SEM) techniques.

Results:

The absorption SPR peaks appeared in the range of 415 to 439 nm. SEM analysis exhibited that particles were spherical in shape with size distribution range from 10 nm to 25 nm. The synthesized silver nanoparticles were pure crystalline in nature as confirmed by the XRD spectra with average crystallite size 7 nm. In vitro antibacterial activity of the prepared silver nanoparticles colloidal samples as well the extract was studied using different concentrations of AgNPs (C1 = 100 μg/ml, C2 = 50 μg/ml, C3 = 25 μg/ml) by well diffusion method against Gram negative Escherichia coli. The antibacterial performance was assessed by measuring the zone of inhibition (ZOI).

Conclusions

The results suggested that AgNPs prepared by green approach can be considered as an alternative antibacterial agent.

Induction of p53 mediated mitochondrial apoptosis and cell cycle arrest in human breast cancer cells by plant mediated synthesis of silver nanoparticles from Bergenia ligulata (Whole plant)

The biological synthesis of nanoparticles is a growing research trend because it has numerous pharmaceutical and biomedical applications. The present study describes the preparation, characterization and anti-cancer evaluation of silver nanoparticles synthesized using an aqueous extract of Bergenia ligulata whole plant as a reducing agent. The physiochemical properties of the Bergenia ligulata silver nanoparticles (BgAgNPs) were measured by ultraviolet-visible spectrophotometry, Fourier transform infrared spectrophotmetry (FTIR), X-ray powder diffraction (XRD) and Scanning electron microscopy (SEM) analysis for identifying functional groups, crystallinity, structural and morphological features, respectively. Further, BgAgNps, along with the Bergenia ligulata aqueous extract (BgAE), were investigated for their effects on cell proliferation and apoptosis through MTT, colony-forming assay, wound-healing assay and flow cytometry-based approaches. The cytotoxic effects were more pronounced in cells treated with BgAgNps in comparison to BgAE. These effects were evidenced by the decreasing cell viability, migration capacity and loss of characteristic morphological features. In addition, BgAgNps unveiled significant induction of apoptosis in human breast cancer (MCF-7) cells, possibly through oxidative stress-mediated reactive oxygen species (ROS) generation and loss of mitochondrial membrane potential (MMP). Moreover, molecular mechanism-based studies revealed that BgAgNps robustly augmented p53 levels and pro-apoptotic downstream targets of p53 like Bax and cleaved caspase 3 in MCF-7 cells. Of note, BgAgNps had little or no cytotoxic effect on p53-deficient cancer cells (Mda-mb-231 and SW-620). These findings confirm that the BgAgNPs exhibited superior anti-cancer potential and could be exploited as a promising, cost-effective, and environmentally benign strategy in treating this disease in the future.

Platinum Nanoparticles in Biomedicine: Preparation, Anti-Cancer Activity, and Drug Delivery Vehicles

Cancer is the main cause of morbidity and mortality worldwide, excluding infectious disease. Because of their lack of specificity in chemotherapy agents are used for cancer treatment, these agents have severe systemic side effects, and gradually lose their therapeutic effects because most cancers become multidrug resistant. Platinum nanoparticles (PtNPs) are relatively new agents that are being tested in cancer therapy. This review covers the various methods for the preparation and physicochemical characterization of PtNPs. PtNPs have been shown to possess some intrinsic anticancer activity, probably due to their antioxidant action, which slows tumor growth. Targeting ligands can be attached to functionalized metal PtNPs to improve their tumor targeting ability. PtNPs-based therapeutic systems can enable the controlled release of drugs, to improve the efficiency and reduce the side effects of cancer therapy. Pt-based materials play a key role in clinical research. Thus, the diagnostic and medical industries are exploring the possibility of using PtNPs as a next-generation anticancer therapeutic agent. Although, biologically prepared nanomaterials exhibit high efficacy with low concentrations, several factors still need to be considered for clinical use of PtNPs such as the source of raw materials, stability, solubility, the method of production, biodistribution, accumulation, controlled release, cell-specific targeting, and toxicological issues to human beings. The development of PtNPs as an anticancer agent is one of the most valuable approaches for cancer treatment. The future of PtNPs in biomedical applications holds great promise, especially in the area of disease diagnosis, early detection, cellular and deep tissue imaging, drug/gene delivery, as well as multifunctional therapeutics.

Valorization of agro-industrial biowaste to green nanomaterials for wastewater treatment: Approaching green chemistry and circular economy principles

Water pollution is one of the most critical issues worldwide and is a priority in all scientific agendas. Green nanotechnology presents a plethora of promising avenues for wastewater treatment. This review discusses the current trends in the valorization of zero-cost, biodegradable, and readily available agro-industrial biowaste to produce green bio-nanocatalysts and bio-nanosorbents for wastewater treatment. The promising roles of green bio-nanocatalysts and bio-nanosorbents in removing organic and inorganic water contaminants are discussed. The potent antimicrobial activity of bio-derived nanodisinfectants against water-borne pathogenic microbes is reviewed. The bioactive molecules involved in the chelation and tailoring of green synthesized nanomaterials are highlighted along with the mechanisms involved. Furthermore, this review emphasizes how the valorization of agro-industrial biowaste to green nanomaterials for wastewater treatment adheres to the fundamental principles of green chemistry, circular economy, nexus thinking, and zero-waste manufacturing. The potential economic, environmental, and health impacts of valorizing agro-industrial biowaste to green nanomaterials are highlighted. The challenges and future outlooks for the management of agro-industrial biowaste and safe application of green nanomaterials for wastewater treatment are summarized.

Green synthesized silver nanoparticles obtained from Stachys schtschegleevii extract: ct-DNA interaction and in silico and in vitro investigation of antimicrobial activity

The aim of this study was the synthesis of Ag nanoparticles (AgNPs) by using Stachys schtschegleevii extract and checking the composition, morphology and size of the green synthesized AgNPs using the analytical techniques (UV-vis, DLS, zeta potential, SEM-EDX, FT-IR and TEM). The TEM images of AgNPs represent a smooth surface and are spherical in shape with an average particle size of 31.43 nm. The antioxidant activities of green synthesized AgNPs were appraised by radical scavenging 1, 1-diphenyl-2-picrylhydrazyl test and the green synthesized AgNPs showed a strong ability to scavenge free radicals. In addition, AgNPs displayed a remarkable antibacterial and antifungal activity against various microorganisms. We employed molecular docking to investigate the AgNPs interaction with Dihydrofolate reductase (DHFR) of Escherichia coli, Staphylococcus aureus, and Candida albicans and there is a good agreement between molecular docking and our experimental results. The result of ct-DNA-AgNPs interaction demonstrated that AgNPs can bind to ct-DNA through partial intercalation binding mode.Communicated by Ramaswamy H. Sarma.

Exploring Pharmacological Mechanisms of Essential Oils on the Central Nervous System

Essential oils (EOs) have been traditionally used as ancient remedies to treat many health disorders due to their enormous biological activities. As mainstream allopathic medication currently used for CNS disorders is associated with adverse effects, the search to obtain safer alternatives as compared to the currently marketed therapies is of tremendous significance. Research conducted suggests that concurrent utilization of allopathic medicines and EOs is synergistically beneficial. Due to their inability to show untoward effects, various scientists have tried to elucidate the pharmacological mechanisms by which these oils exert beneficial effects on the CNS. In this regard, our review aims to improve the understanding of EOs' biological activity on the CNS and to highlight the significance of the utilization of EOs in neuronal disorders, thereby improving patient acceptability of EOs as therapeutic agents. Through data compilation from library searches and electronic databases such as PubMed, Google Scholar, etc., recent preclinical and clinical data, routes of administration, and the required or maximal dosage for the observation of beneficial effects are addressed. We have also highlighted the challenges that require attention for further improving patient compliance, research gaps, and the development of EO-based nanomedicine for targeted therapy and pharmacotherapy.

In Vitro Antioxidant, Antitumor and Photocatalytic Activities of Silver Nanoparticles Synthesized Using Equisetum Species: A Green Approach

The ethanolic extracts of three Equisetum species (E. pratense Ehrh., E. sylvaticum L. and E. telmateia Ehrh.) were used to reduce silver ions to silver nanoparticles (AgNPs). The synthesized AgNPs were characterized using UV-Vis spectrophotometry, Fourier Transform Infrared Spectroscopy (FTIR), Energy Dispersive X-ray (EDX), Transmission Electron Microscopy (TEM) and Dynamic Light Scattering (DLS) measurements. FTIR data revealed the functional groups of biomolecules involved in AgNPs synthesis, such as O-H, C-H, C=O, C-O, and C-C. EDX spectroscopy was used to highlight the presence of silver, while DLS spectroscopy provided information on the mean diameter of AgNPs, that ranged from 74.4 to 314 nm. The negative Zeta potential values (−23.76 for Ep–AgNPs, −29.54 for Es–AgNPs and −20.72 for Et–AgNPs) indicate the stability of the obtained colloidal solution. The study also focused on establishing the photocatalytic activity of AgNPs, which is an important aspect in terms of removing organic dyes from the environment. The best photocatalytic activity was observed for AgNPs obtained from E. telmateia, which degraded malachite green in a proportion of 97.9%. The antioxidant action of the three AgNPs samples was highlighted comparatively through four tests, with the best overall antioxidant capacity being observed for AgNPs obtained using E. sylvaticum. Moreover, the biosynthesized AgNPs showed promising cytotoxic efficacy against cancerous cell line MG63, the AgNPs obtained from E. sylvaticum L. providing the best result, with a LD₅₀ value around 1.5 mg/mL.

Silver Nanoparticles as Potential Antiviral Agents

Since the early 1990s, nanotechnology has led to new horizons in nanomedicine, which encompasses all spheres of science including chemistry, material science, biology, and biotechnology. Emerging viral infections are creating severe hazards to public health worldwide, recently, COVID-19 has caused mass human casualties with significant economic impacts. Interestingly, silver nanoparticles (AgNPs) exhibited the potential to destroy viruses, bacteria, and fungi using various methods. However, developing safe and effective antiviral drugs is challenging, as viruses use host cells for replication. Designing drugs that do not harm host cells while targeting viruses is complicated. In recent years, the impact of AgNPs on viruses has been evaluated. Here, we discuss the potential role of silver nanoparticles as antiviral agents. In this review, we focus on the properties of AgNPs such as their characterization methods, antiviral activity, mechanisms, applications, and toxicity.

Green Synthesis of Metal and Metal Oxide Nanoparticles Using Different Plants’ Parts for Antimicrobial Activity and Anticancer Activity: A Review Article

Nanotechnology emerged as a scientific innovation in the 21st century. Metallic nanoparticles (metal or metal oxide nanoparticles) have attained remarkable popularity due to their interesting biological, physical, chemical, magnetic, and optical properties. Metal-based nanoparticles can be prepared by utilizing different biological, physical, and chemical methods. The biological method is preferred as it provides a green, simple, facile, ecofriendly, rapid, and cost-effective route for the green synthesis of nanoparticles. Plants have complex phytochemical constituents such as carbohydrates, amino acids, phenolics, flavonoids, terpenoids, and proteins, which can behave as reducing and stabilizing agents. However, the mechanism of green synthesis by using plants is still highly debatable. In this report, we summarized basic principles or mechanisms of green synthesis especially for metal or metal oxide (i.e., ZnO, Au, Ag, and TiO2, Fe, Fe2O3, Cu, CuO, Co) nanoparticles. Finally, we explored the medical applications of plant-based nanoparticles in terms of antibacterial, antifungal, and anticancer activity.

Investigation on Green Synthesis, Biocompatibility, and Antibacterial Activity of Silver Nanoparticles Prepared Using Cistus incanus

This paper describes the plant-mediated preparation of silver nanoparticles with aqueous extract and infusion of Cistus incanus leaves. To evaluate aqueous extract and infusion antioxidant capacity and total phenolic content the DPPH and Folin-Ciocalteau methods were utilized. The antioxidant capacity and total phenolic content of extract and infusion were equal to 85.97 ± 6.54 mg gallic acid equivalents per gram of dry weight.; 10.76 ± 0.59 mg/mL and 12.65 ± 1.04 mg gallic acid equivalents per gram of dry weight.; 3.10 ± 0.14 mg/mL, respectively. The formed nanoparticles displayed the characteristic absorption band in the 380-450 nm wavelength range. The average size of particles was in the 68.8-71.2 nm range. Morphology and phase composition analysis revealed the formation of spherical nanoparticles with a face-centred cubic structure. Immune compatibility tests of nanoparticles and plant extracts showed no activation of the THP1-XBlue™ monocyte. Cytotoxicity tests performed with L929 mice fibroblasts showed that nanoparticles should be utilized at a concentration of 16 ppm. The minimum inhibitory concentrations determined with the microdilution method for nanoparticles prepared with plant infusion for S. aureus and S. epidermidis were 2 ppm and 16 ppm, respectively.

Toward a Better Understanding of Metal Nanoparticles, a Novel Strategy from Eucalyptus Plants

Nanotechnology is a promising tool that has opened the doors of improvement to the quality of human's lives through its potential in numerous technological aspects. Green chemistry of nanoscale materials (1-100 nm) is as an effective and sustainable strategy to manufacture homogeneous nanoparticles (NPs) with unique properties, thus making the synthesis of green NPs, especially metal nanoparticles (MNPs), the scientist's core theme. Researchers have tested different organisms to manufacture MNPs and the results of experiments confirmed that plants tend to be the ideal candidate amongst all entities and are suitable to synthesize a wide variety of MNPs. Natural and cultivated Eucalyptus forests are among woody plants used for landscape beautification and as forest products. The present review has been written to reflect the efficacious role of Eucalyptus in the synthesis of MNPs. To better understand this, the route of extracting MNPs from plants, in general, and Eucalyptus, in particular, are discussed. Furthermore, the crucial factors influencing the process of MNP synthesis from Eucalyptus as well as their characterization and recent applications are highlighted. Information gathered in this review is useful to build a basis for new prospective research ideas on how to exploit this woody species in the production of MNPs. Nevertheless, there is a necessity to feed the scientific field with further investigations on wider applications of Eucalyptus-derived MNPs.

Green synthesis of silver nanoparticles using pollen extract: Characterization, assessment of their electrochemical and antioxidant activities

In the present study, a simple, cheaply and environmental friendly method was evaluated for the synthesis of silver nanoparticle via Cupressus sempervirens L. (CSPE) pollen extract as reducing and stabilizing agent. Various parameters such as volume of CSPE, temperature and reaction time on AgNPs formation were investigated spectrophotometrically to optimize reaction conditions. The electrochemical behavior of the biosynthesized AgNPs were investigated by cyclic voltammetry and square wave voltammetry techniques. An electrosensor based on AgNPs modified glassy carbon electrode were constructed and tested on electro reduction of hydrogen peroxide in phosphate buffer medium. The prepared electrosensor could detect the H₂O₂ in the range of 5.0 μM - 2.5 mM with a detection limit of 0.23 μM. In addition, the antioxidant activity of biosynthesized AgNPs were evaluated against DPPH free radical. Results obtained from the antioxidant study suggested that CSPE mediated AgNPs exhibit a good antioxidant effect.

Plant-mediated green synthesis of metal-based nanoparticles for dermopharmaceutical and cosmetic applications

The skin is the primordial barrier that protects the human body against environmental factors. Due to the arise of dermatological pathologies, the development of efficient delivery systems for topical applications has received increased interest. The highest challenge consists of increasing the penetration of the active ingredients through the skin barrier, alongside to the need of obtaining enough skin retention to achieve therapeutic concentrations. Metals, specially noble metals, have been used for years to treat and prevent health issues, among them dermatological disorders. Nanoparticles have been extensively used for topical applications given their advantages, namely by enhancing solubility of apolar drugs, the possibility of controlled release, the higher stability and the capability to target specific areas and delivery of high concentrations of active ingredients. In order to take advantage of the before mentioned unique properties of nanoparticles and the biological activities of metals, various metal-based nanoparticles (MNPs) have been synthesized in the past few years, such as silver (AgNPs), gold (AuNPs), zinc (ZnNPs), zinc oxide (ZnONPs), copper (CuNPs) and copper oxide (CuONPs) nanoparticles. These MNPs are flexible structures that allow the control of physical characteristics, with enhanced surface properties, which provides a high applicability in dermopharmacy and cosmetics. The conventional methods for synthesizing nanoparticles (physical and chemical approaches) are associated with major drawbacks, being the most concerning the high cost (in resources, energy, time and space) and human/environmental toxicity. Hence, the need to develop an alternative synthesis pathway was imposed, giving rise to the green synthesis methodology. In general, green synthesis consist of using biological sources (plants, bacteria or fungi) to synthesize ecological benign, non-hazard and biocompatible nanoparticles. With the development of green synthesis, starting materials have been used more frequently, among them plants. Plant-mediated green synthesis of nanoparticles is based on the use of plant extracts to synthesize nanoparticles, and their outstanding advantages have paved the way for exciting developments on nanoparticle synthesis to the detriment of complex and toxicity-associated chemical and physical synthesis. MNPs produced by plant-mediated synthesis also demonstrate notorious biological activities, i.e., anticancer, antioxidant, anti-inflammatory, antimicrobial, wound healing and antiaging activities. However, safety assessment of phyto MNPs (phyto-MNPs) holds significant importance due to the lack of toxicological studies and the conception issues that some of the available studies show. In general, current studies suggest the biocompatibility and safety of phyto-MNPs, together with significantly improved and relevant biological activities towards dermopharmaceutical and cosmetic applications. Against this backdrop, there is still a long way to run until the application of phyto-MNPs in the medical, pharmaceutical and cosmetic fields, but studies so far show a very high potential towards their clinical translation for dermopharmaceutical and cosmetics applications. This review focuses on phyto-MNPs synthesized resorting to various plant extracts, including their production, characterization and the biological activities that support their topical application for dermopharmaceutical and cosmetic purposes.

The formation and antibacterial activity of Zn/ZnO nanoparticle produced in Pometia pinnata leaf extract solution using a laser ablation technique

The single-step green synthesis has been successfully established to prepare a bi-phase structure of Zn/ZnO nanoparticles using laser ablation in a liquid medium. Nd: YAG laser with the wavelength of 1064 nm was employed to perform the laser ablation in pure water and Pometia pinnata (P. pinnata) leaf extract, with the leaf, were extracted in pure water and some concentration of ethanol. ZnO nanoparticles can be obtained via laser ablation in pure water, while the usage of P. pinnata leaf extract as the solution has caused the appearance of the bi-phase Zn/ZnO nanostructure. X-ray diffraction (XRD) pattern indicates the appearance of Zn peaks alongside with ZnO peaks with the inclusion of P. pinnata leaf extract. Transmission electron microscope (TEM) images show the change of shape from the rod-like shape into a spherical shape and smaller size spherical shape of Zn/ZnO nanoparticles in comparison with ZnO. Noticeable change of UV-visible spectrum emerges as the water was substituted by P. pinnata leaf extract. The zeta potential of Zn/ZnO prepared with P. pinnata extracted in water, with the value of - 18.9 V, reduces down to - 43.5 and - 41.1 for 20-40% of ethanol concentration, respectively. The as-prepared ZnO and Zn/ZnO colloidal samples were evaluated for their antibacterial activities against two strains Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli). Zn/ZnO sample shows a more substantial antibacterial effect in comparison with pure ZnO, no bacteria alive after 12 and 24 h' treatment for E. coli and S. aureus, respectively.

Conifer-Derived Metallic Nanoparticles: Green Synthesis and Biological Applications

The use of metallic nanoparticles in engineering and biomedicine disciplines has gained considerable attention. Scientists are exploring new synthesis protocols of these substances considering their small size and lucrative antimicrobial potential. Among the most economical techniques of synthesis of metallic nanoparticles via chemical routes, which includes the use of chemicals as metal reducing agents, is considered to generate nanoparticles possessing toxicity and biological risk. This limitation of chemically synthesized nanoparticles has engendered the exploration for the ecofriendly synthesis process. Biological or green synthesis approaches have emerged as an effective solution to address the limitations of conventionally synthesized nanoparticles. Nanoparticles synthesized via biological entities obtained from plant extracts exhibit superior effect in comparison to chemical methods. Recently, conifer extracts have been found to be effective in synthesizing metallic nanoparticles through a highly regulated process. The current review highlights the importance of conifers and its extracts in synthesis of metallic nanoparticles. It also discusses the different applications of the conifer extract mediated metallic nanoparticles.

Silver Nanoparticles: Mechanism of Action and Probable Bio-Application

This review is devoted to the medical application of silver nanoparticles produced as a result of "green" synthesis using various living organisms (bacteria, fungi, plants). The proposed mechanisms of AgNPs synthesis and the action mechanisms on target cells are highlighted.

Nano zinc elicited biochemical characterization, nutritional assessment, antioxidant enzymes and fatty acid profiling of rapeseed

The use of nanomaterials in agriculture is a current need and could be helpful in overcoming food security risks. Brassica napus L. is the third most important crop for edible oil, having double low unsaturated fatty acids. In the present study, we investigated the effects of green synthesized Zn NPs on biochemical effects, antioxidant enzymes, nutritional quality parameters and on the fatty acid profile of rapeseed (B. napus). Plant-mediated synthesis of zinc nanoparticles (Zn NPs) was carried out using Mentha arvensis L. leaf extract followed by characterization through ultraviolet-visible spectroscopy (UV-vis), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-Ray (EDX), and X-Ray diffraction (XRD). NPs exhibited irregular shapes ranging in size from 30-70 nm and EDX analysis confirmed 96.08% of Zn in the sample. The investigated biochemical characterization (protein content, proline content, total soluble sugar (TSS), total flavonoid content (TFC), and total phenolic content (TPC) showed a substantial change on exposure to Zn NPs. A dose-dependent gradual increase was observed in the antioxidant enzymes, superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT). Oil and moisture contents dropped significantly from the control level in the rapeseed (B. napus) varieties. However, different trends in nutritional (Zn, Na+, K+) and fatty acid profiling of B. napus have been noted. This study demonstrates that Zn NPs have the potential to improve the biochemical, nutritional, antioxidant enzymes, and fatty acid profile of B. napus varieties.

Platinum Nanoparticles: Green Synthesis and Biomedical Applications

Platinum nanoparticles (PtNPs) have superior physicochemical properties and great potential in biomedical applications. Eco-friendly and economic approaches for the synthesis of PtNPs have been developed to overcome the shortcomings of the traditional physical and chemical methods. Various biogenic entities have been utilized in the green synthesis of PtNPs, including mainly plant extracts, algae, fungi bacteria, and their biomedical effects were assessed. Other biological derivatives have been used in the synthesis of PtNPs such as egg yolk, sheep milk, honey, and bovine serum albumin protein. The green approaches for the synthesis of PtNPs have reduced the reaction time, the energy required, and offered ambient conditions of fabrication. This review highlights the state-of-the-art methods used for green synthesis of PtNPs, synthesis parameters, and their reported biomedical applications.