In vivo synthesis of nanomaterials in plants: location of silver nanoparticles and plant metabolism

In planta synthesis of silver nanoparticles and its effect on adventitious shoot growth and withanolide production in Withania somnifera (L.) Dunal

Silver (Ag) is a non-essential heavy metal with substantial environmental toxicity but an excellent promotor for plant organogenesis. It is used as an elicitor for secondary metabolite production and for in planta synthesis of metal nanoparticles (MNPs). In the present study, the Ag accumulation and reduction capability of in vitro shoots of Withania somnifera and the toxicity and elicitation effect of Ag on in vitro shoots were explored. In vitro shoot cultures of W. somnifera were treated with different concentrations of silver nitrate for a specific treatment period. Growth index, withaferin A, elemental and electron microscopy analyses were done on silver-treated in vitro shoots of W. somnifera. 1 mM silver nitrate treatment for 12 days period was found to give increased growth index (1.425 ± 0.05c) and withaferin A (2.568 ± 0.08e mg g-1) content. The concentration of bioaccumulated Ag in 1 mM silver nitrate treated in vitro shoot was found to be 50.8 ppm. The presence of nano-Ag was also found in the leaves of 1 mM silver nitrate-treated in vitro shoots. In summary, this is the first report portraying the bioaccumulation and in planta reduction capability of the in vitro shoot system of W. somnifera, which makes it a potential medicinal plant of commercial value for silver contaminated soils.

Biogenic nanoparticles: pioneering a new era in breast cancer therapeutics-a comprehensive review

Breast cancer, a widespread malignancy affecting women globally, often arises from mutations in estrogen/progesterone receptors. Conventional treatments like surgery, radiotherapy, and chemotherapy face limitations such as low efficacy and adverse effects. However, nanotechnology offers promise with its unique attributes like targeted delivery and controlled drug release. Yet, challenges like poor size distribution and environmental concerns exist. Biogenic nanotechnology, using natural materials or living cells, is gaining traction for its safety and efficacy in cancer treatment. Biogenic nanoparticles synthesized from plant extracts offer a sustainable and eco-friendly approach, demonstrating significant toxicity against breast cancer cells while sparing healthy ones. They surpass traditional drugs, providing benefits like biocompatibility and targeted delivery. Thus, this current review summarizes the available knowledge on breast cancer (its types, stages, histopathology, symptoms, etiology and epidemiology) with the importance of using biogenic nanomaterials as a new and improved therapy. The novelty of this work lies in its comprehensive examination of the challenges and strategies for advancing the industrial utilization of biogenic metal and metal oxide NPs. Additionally; it underscores the potential of plant-mediated synthesis of biogenic NPs as effective therapies for breast cancer, detailing their mechanisms of action, advantages, and areas for further research.

Bioavailability and translocation of platinum nanoparticles and platinum ions in rice (Oryza sativa L.): Nanoparticles biosynthesis and size-dependent transformation

Metal nanoparticles accumulation and bioavailability in plants raised much attention, specifically transformation and transportation of nanoparticles and their corresponding ions in plants are still unknown. In this work, rice seedlings were exposed to platinum nanoparticles (PtNPs) (with three sizes of 25, 50, and 70 nm) and Pt ions (with doses of 1, 2, and 5 mg/L) to investigate the influences of particle size and Pt form on bioavailability and translocation mechanism of metal nanoparticles. Results based on single particle ICP-MS (SP-ICP-MS) demonstrated the biosynthesis of PtNPs in Pt ions treated rice seedlings. The particle size ranges at 75-79.3 nm were detected in Pt ions exposed rice roots, and further migrated up to rice shoots at 21.7-44.3 nm. After exposed to PtNP-25, the particles could transfer to shoots with the original size distribution detected in roots, even with the PtNPs dose change. PtNP-50 and PtNP-70 translocated to shoots with the particle size increase. For the rice exposure with three dose levels, PtNP-70 had the highest number-based bioconcentration factors (NBCFs) in all Pt species, while Pt ions had the highest bioconcentration factors (BCFs), a range of 1.43-2.04. All PtNPs and Pt ions could be accumulated in rice plants and further transferred to shoots, and particle biosynthesis was proved through SP-ICP-MS. The finding could help us better understand the influence of particle size and form on the transformations of PtNPs in environment.

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.

Impact of palladium nanoparticles on plant and its fungal pathogen. A case study: Brassica napus-Plenodomus lingam

The technological exploitation of palladium or palladium nanoparticles (PdNPs) is increasing, and their wider usage relates to an unwanted release of pollutants into the environment, raising public health concerns about the infiltration of palladium into the consumption chain. This study focuses on the effect of spherical gold-cored PdNPs of 50 ± 10 nm diameter stabilized by sodium citrate on the interaction between an oilseed rape (Brassica napus) and the fungal pathogen Plenodomus lingam. Pretreatment of B. napus cotyledons with PdNPs suspension 24 h before but not 24 h after inoculation with P. lingam resulted in a decrease in the extent of disease symptoms; however, this effect was caused by Pd²⁺ ions (35 mg l^-1 or 70 mg l^-1). Tests to determine any direct antifungal activity on P. lingam in vitro demonstrated that the residual Pd²⁺ ions present in the PdNP suspension were responsible for the antifungal activity and that PdNPs themselves do not contribute to this effect. Brassica napus plants did not show any symptoms of palladium toxicity in any form. PdNPs/Pd²⁺ slightly increased the chlorophyll content and the transcription of pathogenesis-related gene 1 (PR1), indicating the activation of the plant defence system. We conclude that the only toxic effect of the PdNP suspension was on P. lingam via ions and that PdNPs/Pd²⁺ did not have any deleterious effect on the B. napus plants.

pH Alteration in Plant-Mediated Green Synthesis and Its Resultant Impact on Antimicrobial Properties of Silver Nanoparticles (AgNPs)

Plant-mediated green synthesis is a cost-effective and eco-friendly process used to synthesize metallic nanoparticles. Experimental pH is of interest due to its ability to influence nanoparticle size and shape; however, little has been explored in comparison to the influence of this parameter on the therapeutic potential of resultant metallic nanoparticles. Our work investigated the influence of pH alternation on antimicrobial properties of plant-mediated green synthesized (using Spinacia oleracea leaf extract) silver nanoparticles. We further investigated if the antimicrobial activity was sustained at 8 weeks (after initial green synthesis). Antimicrobial properties were evaluated against Escherichia coli, Staphylococcus aureus, and Candida albicans. Our work confirmed that experimental pH in plant-mediated green synthesis of silver nanoparticles influenced their resultant antimicrobial properties. Silver nanoparticles generated at experimental pH 4,5, and nine showed activity against E. coli which was sustained at various levels over 8 weeks. No antimicrobial activity was observed against S. aureus, and weak antimicrobial activity against C. albicans. These interesting findings highlight the importance of experimental pH. Further understanding of the role experimental pH plays on resultant metallic nanoparticle properties as it relates to biological and therapeutic impact is required, which will have an impact on wider applications beyond antimicrobial activity.

Evaluation of Green Silver Nanoparticles Fabricated by Spirulina platensis Phycocyanin as Anticancer and Antimicrobial Agents

Green nanotechnology has attracted attention worldwide, especially in treating cancer and drug-resistant section 6 microbes. This work aims to investigate the anticancer activity of green silver nanoparticles synthesized by Spirulina platensis phycocyanin (SPAgNPs) on two cancer cell lines: Lung cancer cell line (A-549) and breast cancer cell line (MCF-7), compared to the normal human lung cell line (A138). We also aimed to investigate the bactericidal activity against Staphylococcus aureus ATCC29737, Bacillus cereus ATCC11778, Escherichia coli ATCC8379, and Klebsiella pneumonia, as well as the fungicidal activity against Candida albicans (ATCC6019) and Aspergillus niger. The obtained SPAgNPs were spherical and crystalline with a size of 30 nm and a net charge of -26.32 mV. Furthermore, they were surrounded by active groups responsible for stability. The SPAgNPs scavenged 85% of the DPPH radical with a relative increase of approximately 30% over the extract. The proliferation of cancer cells using the MTT assay clarified that both cancer cells (A-549 and MCF-7) are regularly inhibited as they grow on different concentrations of SPAgNPs. The maximum inhibitory effect of SPAgNPs (50 ppm) reached 90.99 and 89.51% against A-549 and MCF7, respectively. Regarding antimicrobial activity, no inhibition zones occurred in bacterial or fungal strains at low concentrations of SPAgNPs and the aqueous Spirulina platensis extract. However, at high concentrations, inhibition zones, especially SPAgNPs, were more potent for all tested microorganisms than their positive controls, with particular reference to Staphylococcus aureus, since the inhibition zones were 3.2, 3.8, and 4.3 mm, and Bacillus cereus was 2.37 mm when compared to tetracycline (2.33 mm). SPAgNPs have more potent antifungal activity, especially against Aspergillus niger, compared to their positive controls. We concluded that SPAgNPs are powerful agents against oxidative stress and microbial infection.

The Imbibition of Pea (Pisum sativum L.) Seeds in Silver Nitrate Reduces Seed Germination, Seedlings Development and Their Metabolic Profile

The use of silver nanoparticles (Ag NPs) on plants is accompanied by the occurrence of Ag⁺ ions, so the research of the effects of both on plants should be related. Therefore, in our study, the effects of Ag NPs suspension (containing Ag⁰ at 20 mg/L) and AgNO₃ solutions (with the concentration of Ag⁺ ions at 20 and 50 mg/L) on the seed germination and early seedling growth (4 days) of pea (Pisum sativum L.) were compared. Both Ag NPs and AgNO₃ did not decrease seed germination, and even stimulated seedling growth. In seedlings developing in the Ag NPs suspension, an increase in monosaccharides, homoserine and malate was noted. In the next experiment, the effect of short-term seed imbibition (8 h) in AgNO₃ at elevated concentrations, ranging from 100 to 1000 mg/L, on the further seed germination, seedling growth (in absence of AgNO₃) and their polar metabolic profiles were evaluated. The seed imbibition in AgNO₃ solutions at 500 and 1000 mg/L reduced seed germination, inhibited seedlings’ growth and caused morphological deformations (twisting and folding of root). The above phytotoxic effects were accompanied by changes in amino acids and soluble carbohydrates profiles, in both sprouts and cotyledons. In deformed sprouts, the content of homoserine and asparagine (major amino acids) decreased, while alanine, glutamic acid, glutamine, proline, GABA (γ-aminobutyric acid) and sucrose increased. The increase in sucrose coincided with a decrease in glucose and fructose. Sprouts, but not cotyledons, also accumulated malic acid and phosphoric acid. Additionally, cotyledons developed from seeds imbibed with AgNO₃ contained raffinose and stachyose, which were not detectable in sprouts and cotyledons of control seedlings. The obtained results suggest the possible disturbances in the mobilization of primary (oligosaccharides) and presumably major storage materials (starch, proteins) as well as in the primary metabolism of developing seedlings.

Green nanopriming: responses of alfalfa (Medicago sativa L.) seedlings to alfalfa extracts capped and light-induced silver nanoparticles

The application of nanotechnology in agriculture can remarkably improve the cultivation and growth of crop plants. Many studies showed that nanoparticles (NPs) made plants grow more vigorously. Light can make NPs aggregated, leading to the reduction of the NPs toxicity. In addition, treatment with NPs had a "hormesis effect" on plants. In this study, light-induced silver nanoparticles (AgNPs) were synthesized by using the alfalfa (Medicago sativa L.) extracts, and then the optimal synthetic condition was determined. Light-induced AgNPs were aggregated, spherical and pink, and they were coated with esters, phenols, acids, terpenes, amino acids and sugars, which were the compositions of alfalfa extracts. The concentration of free Ag⁺ was less than 2 % of the AgNPs concentration. Through nanopriming, Ag⁺ got into the seedlings and caused the impact of AgNPs on alfalfa. Compared with the control group, low concentration of light-induced AgNPs had a positive effect on the photosynthesis. It was also harmless to the leaf cells, and there was no elongation effect on shoots. Although high concentration of AgNPs was especially beneficial to root elongation, it had a slight toxic effect on seedlings due to the accumulation of silver. With the increase of AgNPs concentration, the content of silver in the seedlings increased and the silver enriched in plants was at the mg/kg level. Just as available research reported the toxicity of NPs can be reduced by using suitable synthesis and application methods, the present light induction, active material encapsulation and nanopriming minimized the toxicity of AgNPs to plants, enhancing the antioxidant enzyme system.

Uptake, translocation, and transformation of silver nanoparticles in plants

This article reviews the plant uptake of silver nanoparticles (AgNPs) that occurred in soil systems and the in planta fate of Ag.

Biobased composites from agro-industrial wastes and by-products

The greater awareness of non-renewable natural resources preservation needs has led to the development of more ecological high-performance polymeric materials with new functionalities. In this regard, biobased composites are considered interesting options, especially those obtained from agro-industrial wastes and by-products. These are low-cost raw materials derived from renewable sources, which are mostly biodegradable and would otherwise typically be discarded. In this review, recent and innovative academic studies on composites obtained from biopolymers, natural fillers and active agents, as well as green-synthesized nanoparticles are presented. An in-depth discussion of biobased composites structures, properties, manufacture, and life-cycle assessment (LCA) is provided along with a wide up-to-date overview of the most recent works in the field with appropriate references. Potential uses of biobased composites from agri-food residues such as active and intelligent food packaging, agricultural inputs, tissue engineering, among others are described, considering that the specific characteristics of these materials should match the proposed application.

Synthesis and Processing of Nanomaterials Mediated by Living Organisms

Nanomaterials offer exciting properties and functionalities. However, their production and processing frequently involve complex methods, cumbersome equipment, harsh conditions, and hazardous media. The capability of organisms to accomplish this using mild conditions offers a sustainable, biocompatible, and environmentally friendly alternative. Different nanomaterials such as metal nanoparticles, quantum dots, silica nanostructures, and nanocellulose are being synthesized increasingly through living entities. In addition, the bionanofabrication potential enables also the in situ processing of nanomaterials inside biomatrices with unprecedented outcomes. In this Minireview we present a critical state‐of‐the‐art vision of current nanofabrication approaches mediated by living entities (ranging from unicellular to higher organisms), in order to expand this knowledge and scrutinize future prospects. An efficient interfacial interaction at the nanoscale by green means is within reach through this approach.

Polyphenolic extracts from pomegranate and watermelon wastes as substrate to fabricate sustainable silver nanoparticles with larvicidal effect against Spodoptera littoralis

The agricultural wastes adversely affect the environment; however, they are rich in polyphenols; therefore, this study aimed to employ polyphenol-enriched waste extracts for silver nanoparticles synthesis, and study the larvicidal activity of silver nanoparticles fabricated by pomegranate and watermelon peels extracts (PPAgNPs and WPAgNPs) against all larval instars of Spodoptera littoralis. The polyphenol profile of pomegranate and watermelon peel extracts (PP and WP) and silver nanoparticles was detected by HPLC. The antioxidant activity was estimated by DPPH, and FARP assays and the antimicrobial activity was evaluated by disc assay. The Larvicidal activity of AgNPs against Egyptian leaf worm was performed by dipping technique. The obtained AgNPs were spherical with size ranged 15-85 nm and capped with proteins and polyphenols. The phenolic compounds in silver nanoparticles increased about extracts; therefore, they have the best performance in antioxidant/reducing activity, and inhibit the growth of tested bacteria and yeast. The PPAgNPs were the most effective against the first instar larvae instar (LC50 = 68.32 µg/ml), followed by pomegranate extract with (LC50 = 2852 µg/ml). The results indicated that obvious increase in polyphenols content in silver nanoparticles enhance their larvicidal effect and increasing mortality of 1st larval of S. littoralis Egyptian leafworms causing additive effect and synergism. We recommend recycling phenolic enriched agricultural wastes in producing green silver nanoprticles to control cotton leafworm that causes economic loses to crops.

Silver nanoparticles in aquatic sediments: Occurrence, chemical transformations, toxicity, and analytical methods

Sediments represent the major sink for released silver nanoparticles (AgNPs) in aquatic environments. It is well known that the environmental behavior and toxicity of AgNPs in sediments are governed by their specific chemical species instead of their total concentration. This review focuses on various chemical transformations of AgNPs in sediments, which have not been well outlined before. We first outline the concentrations of AgNPs in sediments. The predicted concentrations are 1-5 µg kg^-1 in most model studies. Once enter sediments, AgNPs are transformed to different species (e.g., Ag₂S, Ag-humic substance complexes, AgCl, and Ag⁺) during multiple chemical transformations, such as oxidative dissolution, sulfidation, chlorination, and complexation. Those chemical behaviors mitigate the toxicity of AgNPs by reducing their availability and decreasing Ag⁺ release. Benthic invertebrates and microbes are prone to be affected by AgNPs. AgNPs are found to be accumulated in sediment-dwelling organisms and transferred to higher trophic levels along the food web. Besides X-ray absorption spectroscopy, reliable separation procedures coupled with detection techniques, are powerful tools that characterize the speciation of AgNPs in sediments. More research is needed to investigate diverse chemical transformations in various sediments through development of novel techniques and mathematical models.

Green Synthesis of Nanomaterials

Nanotechnology is considered one of the paramount forefronts in science over the last decade. Its versatile implementations and fast-growing demand have paved the way for innovative measures for the synthesis of higher quality nanomaterials. In the early stages, traditional synthesis methods were utilized, and they relied on both carcinogenic chemicals and high energy input for production of nano-sized material. The pollution produced as a result of traditional synthesis methods induces a need for environmentally safer synthesis methods. As the downfalls of climate change become more abundant, the scientific community is persistently seeking solutions to combat the devastation caused by toxic production methods. Green methods for nanomaterial synthesis apply natural biological systems to nanomaterial production. The present review highlights the history of nanoparticle synthesis, starting with traditional methods and progressing towards green methods. Green synthesis is a method just as effective, if not more so, than traditional synthesis; it provides a sustainable approach to nanomaterial manufacturing by using naturally sourced starting materials and relying on low energy processes. The recent use of active molecules in natural biological systems such as bacteria, yeast, algae and fungi report successful results in the synthesis of various nanoparticle systems. Thus, the integration of green synthesis in scientific research and mass production provides a potential solution to the limitations of traditional synthesis methods.

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

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

Tumor-targeting inorganic nanomaterials synthesized by living cells

Inorganic nanomaterials (NMs) have shown potential application in tumor-targeting theranostics, owing to their unique physicochemical properties. Some living cells in nature can absorb surrounding ions in the environment and then convert them into nanomaterials after a series of intracellular/extracellular biochemical reactions. Inspired by that, a variety of living cells have been used as biofactories to produce metallic/metallic alloy NMs, metalloid NMs, oxide NMs and chalcogenide NMs, which are usually automatically capped with biomolecules originating from the living cells, benefitting their tumor-targeting applications. In this review, we summarize the biosynthesis of inorganic nanomaterials in different types of living cells including bacteria, fungi, plant cells and animal cells, accompanied by their application in tumor-targeting theranostics. The mechanisms involving inorganic-ion bioreduction and detoxification as well as biomineralization are emphasized. Based on the mechanisms, we describe the size and morphology control of the products via the modulation of precursor ion concentration, pH, temperature, and incubation time, as well as cell metabolism by a genetic engineering strategy. The strengths and weaknesses of these biosynthetic processes are compared in terms of the controllability, scalability and cooperativity during applications. Future research in this area will add to the diversity of available inorganic nanomaterials as well as their quality and biosafety.

Green Synthesis of Gold and Silver Nanoparticles from Plant Extracts and Their Possible Applications as Antimicrobial Agents in the Agricultural Area

Currently, metal nanoparticles have varied uses for different medical, pharmaceutical, and agricultural applications. Nanobiotechnology, combined with green chemistry, has great potential for the development of novel and necessary products that benefit human health, environment, and industries. Green chemistry has an important role due to its contribution to unconventional synthesis methods of gold and silver nanoparticles from plant extracts, which have exhibited antimicrobial potential, among other outstanding properties. Biodiversity-rich countries need to collect and convert knowledge from biological resources into processes, compounds, methods, and tools, which need to be achieved along with sustainable use and exploitation of biological diversity. Therefore, this paper describes the relevant reported green synthesis of gold and silver nanoparticles from plant extracts and their capacity as antimicrobial agents within the agricultural field for fighting against bacterial and fungal pathogens that can cause plant, waterborne, and foodborne diseases. Moreover, this work makes a brief review of nanoparticles' contribution to water treatment and the development of "environmentally-friendly" nanofertilizers, nanopesticides, and nanoherbicides, as well as presenting the harmful effects of nanoparticles accumulation in plants and soils.

Phyto-Mediated Synthesis of Porous Titanium Dioxide Nanoparticles From Withania somnifera Root Extract: Broad-Spectrum Attenuation of Biofilm and Cytotoxic Properties Against HepG2 Cell Lines

There is grave necessity to counter the menace of drug-resistant biofilms of pathogens using nanomaterials. Moreover, we need to produce nanoparticles (NPs) using inexpensive clean biological approaches that demonstrate broad-spectrum inhibition of microbial biofilms and cytotoxicity against HepG2 cell lines. In the current research work, titanium dioxide (TiO2) NPs were fabricated through an environmentally friendly green process using the root extract of Withania somnifera as the stabilizing and reducing agent to examine its antibiofilm and anticancer potential. Further, X-ray diffraction (XRD), Fourier transform infrared (FTIR), scanning electron microscopy (SEM), transmission electron micrograph (TEM), energy-dispersive X-ray spectroscopy (EDS), dynamic light scattering (DLS), thermogravimetric analysis (TGA), and Brunauer-Emmett-Teller (BET) techniques were used for determining the crystallinity, functional groups involved, shape, size, thermal behavior, surface area, and porosity measurement, respectively, of the synthesized TiO2 NPs. Antimicrobial potential of the TiO2 NPs was determined by evaluating the minimum inhibitory concentration (MIC) against Escherichia coli, Pseudomonas aeruginosa, methicillin-resistant Staphylococcus aureus, Listeria monocytogenes, Serratia marcescens, and Candida albicans. Furthermore, at levels below the MIC (0.5 × MIC), TiO2 NPs demonstrated significant inhibition of biofilm formation (43-71%) and mature biofilms (24-64%) in all test pathogens. Cell death due to enhanced reactive oxygen species (ROS) production could be responsible for the impaired biofilm production in TiO2 NP-treated pathogens. The synthesized NPs induced considerable reduction in the viability of HepG2 in vitro and could prove effective in controlling liver cancer. In summary, the green synthesized TiO2 NPs demonstrate multifarious biological properties and could be used as an anti-infective agent to treat biofilm-based infections and cancer.

In Vivo Biosynthesis of Inorganic Nanomaterials Using Eukaryotes-A Review

Bionanotechnology, the use of biological resources to produce novel, valuable nanomaterials, has witnessed tremendous developments over the past two decades. This eco-friendly and sustainable approach enables the synthesis of numerous, diverse types of useful nanomaterials for many medical, commercial, and scientific applications. Countless reviews describing the biosynthesis of nanomaterials have been published. However, to the best of our knowledge, no review has been exclusively focused on the in vivo biosynthesis of inorganic nanomaterials. Therefore, the present review is dedicated to filling this gap by describing the many different facets of the in vivo biosynthesis of nanoparticles (NPs) using living eukaryotic cells and organisms-more specifically, live plants and living biomass of several species of microalgae, yeast, fungus, mammalian cells, and animals. It also highlights the strengths and weaknesses of the synthesis methodologies and the NP characteristics, bio-applications, and proposed synthesis mechanisms. This comprehensive review also brings attention to enabling a better understanding between the living organisms themselves and the synthesis conditions that allow their exploitation as nanobiotechnological production platforms as these might serve as a robust resource to boost and expand the bio-production and use of desirable, functional inorganic nanomaterials.

A Brief Overview on Antioxidant Activity Determination of Silver Nanoparticles

Our objective in this review article is to find out relevant information about methods of determination of antioxidant activity of silver nanoparticles. There are many studies dealing with mentioned problem and herein we summarize the knowledge about methods evaluating the antioxidant activity of silver nanoparticles reported so far. Many authors declare better antioxidant activity of silver nanoparticles compared to the extract used for synthesis of them. In this review, we focused on methods of antioxidant activity determination in detail to find out novel and perspective techniques to solve the general problems associated with the determination of antioxidant activity of silver nanoparticles.

Biosynthesis of Ag nanoparticles and two-dimensional element distribution in Arabidopsis

Metallic nanoparticles can be synthesised in living plants, which provide a friendly approach. In this work, the authors aimed to study the synthesis of silver nanoparticles (AgNPs) in Arabidopsis and the two-dimensional (2D) distribution of Ag and other elements (Ca, P, S, Mg, and CI) in the Arabidopsis plant tissues. The concentrations of Ag in the plant tissues were determined by inductively coupled plasma-atomic emission spectrometer, showing that the majority of Ag was retained in the roots. Transmission electron micrographs showed the morphology of AgNPs and the location in plant cells. The distributions of Cl and Ag were consistent in plant tissues by 2D proton-induced X-ray emission. In conclusion, this is the first report of the AgNP synthesis in Arabidopsis living plants and its 2D distribution of important elements, which provide a new clue for further research.

Biogenic Metal Nanoparticles: A New Approach to Detect Life on Mars?

Metal nanoparticles (MNPs) have been extensively studied. They can be produced via different methods (physical, chemical, or biogenic), but biogenic synthesis has become more relevant, mainly for being referred by many as eco-friendly and more advantageous than others. Biogenic MNPs have been largely used in a wide variety of applications, from industry, to agriculture, to health sectors, among others. Even though they are increasingly researched and used, there is still space for exploring further applications and increasing their functionality and our understanding of their synthesis process. Here, we provide an overview of MNPs and biogenic MNPs, and we analyze the potential application of their formation process to astrobiology and the detection of life on Mars and other worlds. According to current knowledge, we suggest that they can be used as potential biosignatures in extra-terrestrial samples. We present the advantages and disadvantages of this approach, suggest further research, and propose its potential use for the search for life in future space exploration.

Advances in nanomaterials as novel elicitors of pharmacologically active plant specialized metabolites: current status and future outlooks

During the last few decades major advances have shed light on nanotechnology. Nanomaterials have been widely used in various fields such as medicine, energy, cosmetics, electronics, biotechnology and pharmaceuticals. Owing to their unique physicochemical characteristics and nanoscale structures, nanoparticles (NPs) have the capacity to enter into plant cells and interact with intracellular organelles and various metabolites. The effects of NPs on plant growth, development, physiology and biochemistry have been reported, but their impact on plant specialized metabolism (aka as secondary metabolism) still remains obscure. In reaction to environmental stress and elicitors, a common response in plants results in the production or activation of different types of specialized metabolites (e.g., alkaloids, terpenoids, phenolics and flavonoids). These plant specialized metabolites (SMs) are important for plant adaptation to an adverse environment, but also a huge number of them are biologically active and used in various commercially-valued products (pharmacy, cosmetic, agriculture, food/feed). Due to their wide array of applications, SMs have attracted much attention to explore and develop new strategies to enhance their production in plants. In this context, NPs emerged as a novel class of effective elicitors to enhance the production of various plant SMs. In recent years, many reports have been published regarding the elicitation of SMs by different types of NPs. However, in order to achieve an enhanced and sustainable production of these SMs, in-depth studies are required to figure out the most suitable NP in terms of type, size and/or effective concentration, along with a more complete understanding about their uptake, translocation, internalization and elicitation mechanisms. Herein, we are presenting a comprehensive and critical account of the plant SMs elicitation capacities of the three main classes of nanomaterials (i.e., metallic NPs (MNPs), metal oxide NPs (MONPs) and carbon related nanomaterials). Their different proposed uptake, translocation and internalization pathways as well as elicitation mechanism along with their possible deleterious effect on plant SMs and/or phytotoxic effects are summarized. We also identified and critically discussed the current research gaps existing in this field and requiring future investigation to further improve the use of these nanomaterials for an efficient production of plant SMs.

Green Synthesis of Silver Nanoparticles Using Bilberry and Red Currant Waste Extracts

The production of silver nanoparticles (Ag-NPs) from bilberry waste (BW) and red currant waste (RCW) extracts was studied. Red fruit extracts were obtained by treating BW and RCW with aqueous ethanol (50% v/v) at 40 °C. The formation of nanoparticles was monitored spectrophotometrically by measuring the intensity of the surface plasmon resonance band (SPR) of silver. The effects of temperature (20–60 °C) and pH (8–12) on the reaction kinetics and on the properties of Ag-NPs were investigated. Characterization by XRD and dynamic light scattering (DLS) techniques showed that Ag-NPs were highly crystalline, with a face-centered cubic structure and a hydrodynamic diameter of 25–65 nm. The zeta potential was in the range of −35.6 to −20.5 mV. Nanoparticles obtained from BW were slightly smaller and more stable than those from RCW. A kinetic analysis by the initial-rate method showed that there was an optimum pH, around 11, for the production of Ag-NPs. Overall, the results obtained suggest that BW and RCW can be advantageously used as a source of reducing and stabilizing agents for the green synthesis of Ag-NPs.

Effect of Nanoparticles Surface Charge on the Arabidopsis thaliana (L.) Roots Development and Their Movement into the Root Cells and Protoplasts

Increasing usage of gold nanoparticles (AuNPs) in different industrial areas inevitably leads to their release into the environment. Thus, living organisms, including plants, may be exposed to a direct contact with nanoparticles (NPs). Despite the growing amount of research on this topic, our knowledge about NPs uptake by plants and their influence on different developmental processes is still insufficient. The first physical barrier for NPs penetration to the plant body is a cell wall which protects cytoplasm from external factors and environmental stresses. The absence of a cell wall may facilitate the internalization of various particles including NPs. Our studies have shown that AuNPs, independently of their surface charge, did not cross the cell wall of Arabidopsis thaliana (L.) roots. However, the research carried out with using light and transmission electron microscope revealed that AuNPs with different surface charge caused diverse changes in the root’s histology and ultrastructure. Therefore, we verified whether this is only the wall which protects cells against particles penetration and for this purpose we used protoplasts culture. It has been shown that plasma membrane (PM) is not a barrier for positively charged (+) AuNPs and negatively charged (−) AuNPs, which passage to the cell.

Synthesis and therapeutic potential of silver nanomaterials derived from plant extracts

Silver nanoparticles (AgNPs) have attracted a great deal of attention in the recent years. It is mostly due to their availability, chemical stability, catalytic activity, conductivity, biocompatibility, antimicrobial activity and intrinsic therapeutic properties. There are three major approaches for AgNPs synthesis; i.e., chemical, physical, and biological methods. Today, many of chemical and physical methods have become less popular due to using hazardous chemicals or their high costs, respectively. The biological method has introduced an appropriate substitute synthesis strategy for the traditional physical and chemical approaches. The utilization of the plant extracts as reducing, stabilizing and coating agent of AgNPs is an interesting eco-friendly approach leading to high efficiency. The antimicrobial and anticancer synergistic effects among the AgNPs and phytochemicals will enhance their therapeutic potentials. Surprisingly, although many studies have demonstrated the significant enhancement in cytotoxic activities of plant-mediated AgNPs toward cancerous cells, these nanoparticles have been found nontoxic to normal human cells in their therapeutic concentrations. This review provides a comprehensive insight into the mechanism of plant-mediated AgNPs synthesis, their antimicrobial and cytotoxic activities as well as their applications.

Uptake and Transformation of Silver Nanoparticles and Ions by Rice Plants Revealed by Dual Stable Isotope Tracing

Knowledge on the uptake and transformation of silver nanoparticles (AgNPs) and Ag⁺ ions by organisms is critical for understanding their toxicity. Herein, the differential uptake, transformation, and translocation of AgNPs and Ag⁺ ions in hydroponic rice ( Oryza sativa L.) is assessed in modified Hewitt (with Cl^- ions, HS(Cl)) and Hogland solutions (without Cl^- ions, HS) using dual stable isotope tracing (¹⁰⁷AgNO₃ and ¹⁰⁹AgNPs). After coexposure to ¹⁰⁷Ag⁺ ions and ¹⁰⁹AgNPs at 50 μg L^-1 (as Ag for both) for 14 days, a stimulatory effect was observed on root elongation (increased by 68.8 and 71.9% for HS(Cl) and HS, respectively). Most of the Ag⁺ ions (from ¹⁰⁷Ag⁺ ions and ¹⁰⁹AgNPs) were retained on the root surface, while the occurrence of AgNPs (from ¹⁰⁹AgNPs and ¹⁰⁷Ag⁺ ions) was observed in the root, suggesting the direct uptake of AgNPs and/or reduction of Ag⁺ ions. Higher fractions of Ag⁺ ions in the shoot suggest an in vivo oxidation of AgNPs. These results demonstrated the intertransformation between Ag⁺ ions and AgNPs and the role of AgNPs as carriers and sources of Ag⁺ ions in organisms, which is helpful for understanding the fate and toxicology of Ag.

Single particle ICP-MS and GC-MS provide a new insight into the formation mechanisms during the green synthesis of AgNPs

For the first time, the formation kinetics and responsible metabolites during the green synthesis of AgNPs were elucidated by sp-ICP-MS and GC-MS.

Silver nanoparticles synthesized with Eucalyptus critriodora ethanol leaf extract stimulate antibacterial activity against clinically multidrug-resistant Acinetobacter baumannii isolated from pneumonia patients

The increasing multidrug resistance of Acinetobacter baumannii has been highlighted as a worldwide therapeutic problem. Despite the wide range of studies on green synthesis of silver nanoparticles, there is currently no alternative treatment for MDR A. baumannii infection. This study investigated the potential of silver nanoparticles synthesized with Eucalyptus critriodora leaf extract as an inhibitor of MDR A. baumannii infection. The results demonstrated that silver nanoparticles synthesized with E. critriodora leaf extract triggered MDR A. baumannii DNA condensation, induced bacterial cell death and had a significant effect on biofilm formation, biofilm-grown cells, bacterial attachment and invasion of human lung cells in a concentration dependent manner. Silver nanoparticles synthesized with E. critriodora leaf extract had no obvious effects on the viability of human lung cells. The synthesized silver nanoparticles inhibited MDR A. baumannii infection by approximately 90% without cytotoxicity with a 50% effective concentration of 0.028 μg/ml. Thus silver nanoparticles with E. critriodora leaf extract had the potential to be a promising anti-MDR A. baumannii agent for effective treatment and they point the way to further development of a wide range of effective biomedical applications.

In vivo biosynthesis and spatial distribution of Ag nanoparticles in maize (Zea mays L.)

Nanoparticles (NPs), especially biosynthesised in living plants by absorbing soluble salts and reducing metal ions, are extensively used in various fields. This work aimed at investigating the in vivo biosynthesis of silver NPs (Ag-NPs) in maize and the spatial distribution of the NPs and some important nutrient elements in the plant. The content of silver in plant was examined by inductively coupled plasma-atomic emission spectrometer showing that Ag can be absorbed by plant as soluble salts. The NPs in different parts of maize plant were detected and analysed by transmission electron microscopy, demonstrating the synthesis of NPs and their transport from the root to the shoots. Two-dimensional proton induced X-ray emission of silver, chlorine and several nutrient elements elucidated the possible relationship between synthesis of NPs and several nutrient elements in plant tissues. To their knowledge, this is the first report of possibility of synthesis of Ag-NPs in living plants maize (Zea mays L.). This study presents direct evidence for synthesis of NPs and distribution of related nutrient elements in maize, which has great significance for studying synthetic application of NPs in crop plants.

Nanoparticle-plant interaction: Implications in energy, environment, and agriculture

In the recent techno-scientific revolution, nanotechnology has gained popularity at a rapid pace in different sectors and disciplines, specifically environmental, sensing, bioenergy, and agricultural systems. Controlled, easy, economical, and safe synthesis of nanomaterials is desired for the development of new-age nanotechnology. In general, nanomaterial synthesis techniques, such as chemical synthesis, are not completely safe or environmentally friendly due to harmful chemicals used or to toxic by-products produced. Moreover, a few nanomaterials are present as by-product during washing process, which may accumulate in water, air, and soil system to pose serious threats to plants, animals, and microbes. In contrast, using plants for nanomaterial (especially nanoparticle) synthesis has proven to be environmentally safe and economical. The role of plants as a source of nanoparticles is also likely to expand the number of options for sustainable green renewable energy, especially in biorefineries. Despite several advantages of nanotechnology, the nano-revolution has aroused concerns in terms of the fate of nanoparticles in the environment because of the potential health impacts caused by nanotoxicity upon their release. In the present panoramic review, we discuss the possibility that a multitudinous array of nanoparticles may find applications convergent with human welfare based on the synthesis of diverse nanoparticles from plants and their extracts. The significance of plant-nanoparticle interactions has been elucidated further for nanoparticle synthesis, applications of nanoparticles, and the disadvantages of using plants for synthesizing nanoparticles. Finally, we discuss future prospects of plant-nanoparticle interactions in relation to the environment, energy, and agriculture with implications in nanotechnology.

Broad‐spectrum inhibitory effect of green synthesised silver nanoparticles from Withania somnifera (L.) on microbial growth, biofilm and respiration: a putative mechanistic approach

Multi‐drug resistance in pathogenic bacteria has created immense clinical problem globally. To address these, there is need to develop new therapeutic strategies to combat bacterial infections. Silver nanoparticles (AgNPs) might prove to be next generation nano‐antibiotics. However, improved efficacy and broad‐spectrum activity is still needed to be evaluated and understood. The authors have synthesised AgNPs from Withania somnifera (WS) by green process and characterised. The effect of WS‐AgNPs on growth kinetics, biofilm inhibition as well as eradication of preformed biofilms on both gram‐positive and gram‐negative pathogenic bacteria was evaluated. The authors have demonstrated the inhibitory effect on bacterial respiration and disruption of membrane permeability and integrity. It was found that WS‐AgNPs inhibited growth of pathogenic bacteria even at 16 µg/ml. At sub‐minimum inhibitory concentration concentration, there was approximately 50% inhibition in biofilm formation which was further validated by light and electron microscopy. WS‐AgNPs also eradicated the performed biofilms by varying levels at elevated concentration. The bacterial respiration was also significantly inhibited. Interaction of WS‐AgNPs with test pathogen caused the disruption of cell membrane leading to leakage of cellular content. The production of intracellular reactive oxygen species reveals that WS‐AgNPs exerted oxidative stress inside bacterial cell causing microbial growth inhibition and disrupting cellular functions.

Plant extracts as green reductants for the synthesis of silver nanoparticles: lessons from chemical synthesis

From conventional synthesis to green transformations: a brief literature overview and insight for the synthesis of Ag nanoparticles.

Effect of Initial Speciation of Copper- and Silver-Based Nanoparticles on Their Long-Term Fate and Phytoavailability in Freshwater Wetland Mesocosms

Ag⁰- and CuO-engineered nanomaterials (ENMs) or their sulfidized forms are introduced into freshwater wetlands through wastewater effluent and agricultural runoff. Knowledge about the rates of transformations of these ENMs in realistic environments and the impact of the form of the incoming ENM (i.e., sulfidized or pristine) on bioavailability and fate is limited. Here, five freshwater wetland mesocosms were exposed to 3 g of total metal as CuO, CuS, Ag⁰, or Ag₂S ENMs or soluble CuNO₃ added weekly for 1 month. Total metal and metal speciation was measured in sediment and plant samples collected 1, 3, 6, and 9 months after addition. The form of the added ENM did not affect the metal distribution, and ENMs distributed similarly to added ionic Cu or Ag. For the dosing condition used, ∼50% of the added Ag or Cu metal mass was found in Egeria densa plant tissue, with the remainder primarily in the surficial sediment. Ag⁰ and CuO ENMs transformed quickly in sediment, with no evidence of CuO and only ∼4% of silver present as Ag⁰ ENM 1 week after the last ENM addition. In contrast to sediment, Ag⁰ and CuO ENMs were persistent in E. densa tissues for up to 9 and 6 months, respectively. The persistence of ENMs in E. densa suggests that chronic exposures, or food web transfers, for both the transformed and the initially added ENMs are possible.

Oral Exposure to Silver Nanoparticles or Silver Ions May Aggravate Fatty Liver Disease in Overweight Mice

As the applications and environmental release of silver ions and nanoparticles are increasing, increasing human exposure to these pollutants has become an emerging health concern. The impeding effects of such pollutants on susceptible populations are severely under-studied. Here, we demonstrate that silver nanoparticles (Ag NPs), at a dose that causes no general toxicity in normal mice, promotes the progression of fatty liver disease from steatosis to steatohepatitis only in overweight mice. Exposure to Ag⁺ ions induces the same effects in overweight mice. Ag NPs rather than Ag⁺ ions cause this disease progression based on our findings that Ag⁺ ions are partly reduced to Ag NPs in fatty livers, and the toxic effect is correlated with the liver dose of Ag NPs, not Ag⁺ ions. Furthermore, the Ag NP-induced pro-inflammatory activation of Kupffer cells in the liver, enhancement of hepatic inflammation, and suppression of fatty acid oxidation are identified as key factors in the underlying mechanisms.

Uptake and Distribution of Silver in the Aquatic Plant Landoltia punctata (Duckweed) Exposed to Silver and Silver Sulfide Nanoparticles

Aquatic ecosystems are expected to receive Ag⁰ and Ag₂S nanoparticles (NPs) through anthropogenic waste streams. The speciation of silver in Ag-NPs affects their fate in ecosystems, but its influence on interactions with aquatic plants is still unclear. Here, the Ag speciation and distribution was measured in an aquatic plant, duckweed (Landoltia punctata), exposed to Ag⁰ or Ag₂S NPs, or to AgNO₃. The silver distribution in duckweed roots was visualized using synchrotron-based micro X-ray fluorescence (XRF) mapping and Ag speciation was determined using extended X-ray absorption fine structure (EXAFS) spectroscopy. Duckweed exposed to Ag₂S-NPs or Ag⁰-NPs accumulated similar Ag concentrations despite an order of magnitude smaller dissolved Ag fraction measured in the exposure medium for Ag₂S-NPs compared to Ag⁰-NPs. By 24 h after exposure, all three forms of silver had accumulated on and partially in the roots regardless of the form of Ag exposed to the plants. Once associated with duckweed tissue, Ag⁰-NPs had transformed primarily into silver sulfide and silver thiol species. This suggests that plant defenses were active within or at the root surface. The Ag₂S-NPs remained as Ag₂S, while AgNO₃ exposure led to Ag⁰ and sulfur-associated Ag species in plant tissue. Thus, regardless of initial speciation, Ag was readily available to duckweed.

Biogenic synthesis and spatial distribution of silver nanoparticles in the legume mungbean plant (Vigna radiata L.)

The present investigation aimed to study the in vivo synthesis of silver nanoparticles (AgNPs) in the legume Vigna radiata. The level of plant metabolites such as total phenolics, lipid, terpenoids, alkaloids and amino acid increased by 65%, 133%, 19%, 67% and 35%, respectively, in AgNO₃ (100 mg L^-1) treated plants compared to control. Whereas protein and sugar contents in the treated plants were reduced by 38% and 27%, respectively. FTIR analysis of AgNO₃ (20-100 mg L^-1) treated plants exhibited changes in the IR regions between 3297 and 3363 cm^-1, 1635-1619 cm^-1, 1249-1266 cm^-1 and that corresponded to alterations in OH groups of carbohydrates, OH and NH groups of amide I and II regions of protein, when compared with the control. Transmission electron micrographs showed the spatial distribution of AgNPs in the chloroplast, cytoplasmic spaces, vacuolar and nucleolar plant regions. Metal quantification in different tissues of plants exposed to 20-100 mg L^-1 AgNO₃ showed about a 22 fold accumulation of Ag in roots as compared to shoots. The phytotoxic parameters such as percent seed germination and shoot elongation remained almost unaltered at low AgNO₃ doses (20-50 mg L^-1). However, at higher levels of exposure (100 mg L^-1), the percent seed germination as well as root and shoot elongation exhibited concentration dependent decline. In conclusion, synthesis of AgNPs in V. radiata particularly at lower doses of AgNO₃, could be used as a sustainable and environmentally safe technology for large scale production of metal nanoparticles.

Engineered nanomaterial-mediated changes in the metabolism of terrestrial plants

Engineered nanomaterials (ENMs) possess remarkable physicochemical characteristics suitable for different applications in medicine, pharmaceuticals, biotechnology, energy, cosmetics and electronics. Because of their ultrafine size and high surface reactivity, ENMs can enter plant cells and interact with intracellular structures and metabolic pathways which may produce toxicity or promote plant growth and development by diverse mechanisms. Depending on their type and concentration, ENMs can have positive or negative effects on photosynthesis, photochemical fluorescence and quantum yield as well as photosynthetic pigments status of the plants. Some studies have shown that ENMs can improve photosynthetic efficiency via increasing chlorophyll content and light absorption and also broadening the spectrum of captured light, suggesting that photosynthesis can be nano-engineered for harnessing more solar energy. Both up- and down-regulation of primary metabolites such as proteins and carbohydrates have been observed following exposure of plants to various ENMs. The potential capacity of ENMs for changing the rate of primary metabolites lies in their close relationship with activation and biosynthesis of the key enzymes. Several classes of secondary metabolites such as phenolics, flavonoids, and alkaloids have been shown to be induced (mostly accompanied by stress-related factors) in plants exposed to different ENMs, highlighting their great potential as elicitors to enhance both quantity and quality of biologically active secondary metabolites. Considering reports on both positive and negative effects of ENMs on plant metabolism, in-depth studies are warranted to figure out the most appropriate ENMs (type, size and optimal concentration) in order to achieve the desirable effect on specific metabolites in a given plant species. In this review, we summarize the studies performed on the impacts of ENMs on biosynthesis of plant primary and secondary metabolites and mention the research gaps that currently exist in this field.

Speciation Matters: Bioavailability of Silver and Silver Sulfide Nanoparticles to Alfalfa (Medicago sativa)

Terrestrial crops are directly exposed to silver nanoparticles (Ag-NPs) and their environmentally transformed analog silver sulfide nanoparticles (Ag2S-NPs) when wastewater treatment biosolids are applied as fertilizer to agricultural soils. This leads to a need to understand their bioavailability to plants. In the present study, the mechanisms of uptake and distribution of silver in alfalfa (Medicago sativa) were quantified and visualized upon hydroponic exposure to Ag-NPs, Ag2S-NPs, and AgNO3 at 3 mg total Ag/L. Total silver uptake was measured in dried roots and shoots, and the spatial distribution of elements was investigated using transmission electron microscopy (TEM) and synchrotron-based X-ray imaging techniques. Despite large differences in release of Ag(+) ions from the particles, Ag-NPs, Ag2S-NPs, and Ag(+) became associated with plant roots to a similar degree, and exhibited similarly limited (<1%) amounts of translocation of silver into the shoot system. X-ray fluorescence (XRF) mapping revealed differences in the distribution of Ag into roots for each treatment. Silver nanoparticles mainly accumulated in the (columella) border cells and elongation zone, whereas Ag(+) accumulated more uniformly throughout the root. In contrast, Ag2S-NPs remained largely adhered to the root exterior, and the presence of cytoplasmic nano-SixOy aggregates was observed. Exclusively in roots exposed to particulate silver, NPs smaller than the originally dosed NPs were identified by TEM in the cell walls. The apparent accumulation of Ag in the root apoplast determined by XRF, and the presence of small NPs in root cell walls suggests uptake of partially dissolved NPs and translocation along the apoplast.

Microwave Accelerated Green Synthesis of Stable Silver Nanoparticles with Eucalyptus globulus Leaf Extract and Their Antibacterial and Antibiofilm Activity on Clinical Isolates

A simple and rapid microwave assisted method of green synthesis of silver nanoparticles (AgNPs) was developed using aqueous leaf extract of Eucalyptus globulus(ELE), and their antibacterial and antibiofilm potential investigated. With this aim, the aqueous solutions of ELE and AgNO3(1 mM) were mixed (1:4 v/v), and microwave irradiated at 2450 Mhz, for 30 sec. The instant color change of the ELE-AgNO3 mixture from pale yellow to dark brown indicated ELE-AgNPs synthesis. The intensity of peak at 428 nm in UV-Vis spectra, due to the surface plasmon resonance of AgNPs, varied with the amount of ELE, AgNO3 concentration, pH and time of incubation. The biosynthesized ELE-AgNPs were characterized by UV-visible spectroscopy, XRD, TEM, SEM-EDX, FTIR and TGA analyses. The size of ELE-AgNPs was determined to be in range of 1.9-4.3 nm and 5-25 nm, with and without microwave treatment, respectively. SEM exhibited the capping of AgNPs with the ELE constituents, and validated by FTIR analysis. The FTIR data revealed the presence of plant organic constituents and metabolites bound to ELE-AgNPs, which contributes for their stability. The antimicrobial activity of ELE-AgNPs was assessed by growth and biofilm inhibition of extended spectrum β-lactamase (ESBL) producing Pseudomonas aeruginosa, Escherichia coli and methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-sensitive Staphylococcus aureus (MSSA) clinical bacterial isolates. The results demonstrated that S. aureus were more sensitive to ELE-AgNPs than E. coli and P. aeruginosa. MRSA exhibited higher sensitive than MSSA, whereas P. aeruginosa were more sensitive than E. coli to ELE-AgNPs treatment. Also, significant (83 ± 3% and 84 ± 5%) biofilm inhibition was observed in case of S. aureus and P. aeruginosa, respectively. The results elucidated environmentally friendly, economical and quick method for production of colloidal bio-functionalized ELE-AgNPs, for effectual clinical applications, as broad spectrum antibacterial agents and biofilm inhibitors.