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Nanoparticle synthesis under environmentally friendly conditions has been conducted utilizing natural resources in order to reduce the reliance on hazardous chemicals. For example, the utilization of microbial synthesis has enabled the production of nanoparticles that exhibit biocompatibility, stability, and safety. Microorganisms facilitate the growth of crystals while preventing aggregation. They serve as both reducing agents and capping agents by offering enzymes, peptides, poly(amino acids), polyhydroxyalkanoate, and polysaccharides. In this review, we present an overview of nanoparticle synthesis based on microorganisms including bacteria, fungi, algae, and actinobacteria, encompassing metals such as gold (Au), silver (Ag), platinum (Pt), palladium (Pd), copper (Cu), titanium dioxide ((TiO2), zinc oxide (ZnO), iron oxide (Fe2O3), and selenium (Se). The nanoparticles typically vary in size from 1 to 100 nm and exhibit various shapes including spherical, rod-shaped, triangular, cubic, and hexagonal shapes. Additionally, this review discusses the mechanisms behind the synthesis of metal nanoparticles by microorganisms, whether they occur intracellularly or extracellularly. [ABSTRACT FROM AUTHOR]

Nanoparticles, nowadays, are being used in multiple applications such as therapeutics, industries, healthcare, cosmetics, and wound healing. Nanoparticles are entirely distinct from bulk particles as they have a giant surface area to volume ratio, therefore, showing various mechanical, electrical, physical, chemical, and optical properties, and thus, being used in different properties. As there are so many applications of metallic nanoparticles, there is a requirement for an efficient method for nanoparticle synthesis because the conventional chemical methods used to synthesize nanoparticles have limitations such as high cost and negative environmental impact. To overcome these drawbacks, green methods for nanoparticle synthesis have emerged as an eco-friendly and cost-efficient alternative. The green method for nanoparticle amalgam is cost-efficient and eco-friendly, unlike the chemical technique for nanoparticle synthesis. A variety of dimensions of nanoparticles can be synthesized by a substitute of the plant's extract. Moreover, there is no requirement for external stabilizing agents and the involvement of harmful chemicals. This review aims to investigate how plant compounds can be used to synthesize silver nanoparticles and to evaluate the potential of plant extracts as reducing and stabilizing agents in the green synthesis of metallic nanoparticles. This review seeks to investigate the green production of metallic nanoparticles using plant-derived chemicals and to assess the potential of plant extracts as reducing and stabilizing agents. The study investigates the function of numerous plant substances in the synthesis process, such as flavonoids, alkaloids, terpenoids, saponins, and phenols. The paper also examines various methods for figuring out the morphology of nanoparticles created from various plant parts and their prospective uses as antibacterial agents, wastewater treatment, and reactive oxygen species modulators. This review offers insightful information about the possible uses of metallic nanoparticles by highlighting the advantages of environmentally friendly processes for the manufacture of silver nanoparticles. [ABSTRACT FROM AUTHOR]

Green synthesis reduces the production of deleterious products through sustainable and eco-friendly synthesis procedures by using natural resources such as green materials. The present work reports the green synthesis of metal nanoparticles to minimise waste products and implement sustainable processes. Environmental sustainability will increase the healthy environment by reducing hazardous products to the environment. The research community attracts green plants and their products for materials production due to their nontoxic nature to the environment and human health. The current report is new experimentation for nanoparticles by use of green materials with biological reduction method. Silver and gold nanoparticles were synthesized by use of Butea monosperma plant leaves extract. Potential applications of the green derived nanoparticles are known for biological applications and environmental remediation is discussed. The mechanisms of the biological activity of the nanoparticles are also reported. [ABSTRACT FROM AUTHOR]

The ZnO, MgO, NiO, and AlO nanoparticles and Zn–Al and Mg–Ni composite oxides were synthesized by the green method from the Prunus persica leaves extract. The synthesized nanoparticles were characterized through FT-IR, XRD, SEM, and TEM. The FT-IR study was carried out to find out the presence of various functional groups in nanoparticles. Their size was studied by the XRD method which exposed that the nanoparticles were in the range of 19–29 nm, and the size and morphology were studied by SEM, which was further confirmed by TEM. The synthesized nanoparticles were tested for antibacterial activity. In particular, ZnO showed a good inhibitory effect with 22.31 mm of inhibition against Pseudomonas aeruginosa. [ABSTRACT FROM AUTHOR]

Biosynthesis of nanoparticles is the preferred route for the fabrication of biocompatible and cheaper drugs. In this study, the extract and major secondary metabolite from Helichrysum aureonitens, 3,5-dihydroxy-6,7,8-trimethoxyflavone, were used to synthesize silver and zinc oxide nanoparticles. Spectroscopic and microscopic techniques confirmed the formation of the nanoparticles. The flavone alone showed higher DPPH radical scavenging ability (IC50 = 487.1 μg mL−1) relative to the control, butylated hydroxytoluene. In addition, silver nanoparticles synthesized using the flavone had higher ferric reducing potential (Fe3+ to Fe2+) compared to the other test samples. The cytotoxic activity of the plant extract, the flavone, and their biosynthesized nanoparticles was also investigated using the MTT assay against the cancerous MCF-7 (breast adenocarcinoma) and A549 (human lung adenocarcinoma)), and non-cancerous HEK293 (human embryonic kidney) cell lines. The plant extract decreased the cell viability of A549 (IC50 = 68.6 μg mL−1) without being cytotoxic against HEK293, even at high concentrations. Silver nanoparticles significantly decreased cell viability of A549 and moderately decreased cell viability of MCF-7 but induced cell death of HEK293 even at low concentrations. This study provides a green synthesis route for silver and zinc oxide nanoparticles and confirms the therapeutic effectiveness of H. aureonitens, thereby validating its use in ethnomedicine. [ABSTRACT FROM AUTHOR]

Green synthesis of nanoparticles provides an advancement over chemical and physical methods given its cost-effectively, environment-friendly, facile, and suitability for large-scale industrial production. Due to their characteristics, silver nanoparticles are exploited in various fields such as developing electronic devices, biosensing platforms, catalysts, wastewater purification, biomedicine, antifungal, and antibacterial agent. In this study, silver nanoparticles (Ag-NPs) were synthesized using leaves extract of Biarum chaduchrum at ambient temperature, and characterized through transmission electron microscopy, particle size analyzer, and fourier transform infrared spectroscopy. The average size of synthesized Ag-NPs was estimated at 100 nm with a spherical shape. In addition, the antibacterial activity of nanoparticles against Staphylococcusaureus, Enterococcus faecalis, Escherichia coli, and Pseudomonas aeruginosa was tested by minimum inhibitory concentration analysis. According to the results and observations, this procedure can be applied for large-scale synthesis of Ag-NPs and other notable metal nanoparticles with medicinal and industrial use. [ABSTRACT FROM AUTHOR]

Metal nanoparticles synthesis using plant extracts and the study of their medicinal effects is a relatively new topic. Many chemical techniques have been proposed for the synthesis of silver nanoparticles (AgNPs), but green synthesis has a special place due to its clean and non-toxicity. Eryngium bungei Boiss plant was selected for this study due to its reducing properties and medicinal properties. The effect of various factors including concentration of silver nitrate, contact time and pH were investigated to reach optimum conditions. Silver nanoparticles were synthesized by the reaction between extract and silver nitrate after 20 min at room temperature and pH 12. The obtained nanoparticles were analyzed by XRD, UV–Vis, FESEM, EDX analysis to determine the crystals, morphology, identification of constituents, identification of unknown substances and particle distribution, respectively. The absorption of silver nanoparticles at 438 nm was measured using spectrophotometer machine. Particle size, morphology and antibacterial activity against standard strains of Escherichia coli (E. coli; ATCC® 25922™), Klebsiella pneumoniae (K. pneumonia; PTCC® 700603™) and Staphylococcus aureus (S. aureus; PTCC® 16538™) were investigated and the results showed that the synthesized silver nanoparticles have antibacterial properties. Due to the antibacterial results, biosynthesized silver nanoparticles enhanced antibacterial efficiency against S. aureus, K. pneumonia and E. coli bacteria with MIC value of 27.34, 27.34, 6.83 µg/ml and MBC value of 54.68, 109.3 and 13.67 µg/ml, respectively. The results of this study showed that the synthesis of silver nanoparticles can be performed using the extract of Eryngium bungei Boiss and the synthesized nanoparticles by this extract have effective antibacterial effects. [ABSTRACT FROM AUTHOR]

The present study investigated the possible influence of enzymatic browning of banana peel over the production of silver nanoparticles (AgNPs). Firstly, aqueous extracts of banana peel were prepared at different times after peeling and they were used as reducing and stabilizing agents for the production of AgNPs as monitored by visual inspection and spectrophotometry. Hydrodynamic diameters, polydispersity indexes, and Zeta potentials of the produced AgNPs were evaluated. Besides, antimicrobial activities of the AgNPs produced in the moment of peeling and after up to 2 h were assessed. As longer the period of time passed after peeling, AgNPs produced showed a tendency to decrease the size, to become with Zeta potential more negative, and to stabilize their polydispersity indexes. Antimicrobial assays showed that the two tested AgNPs were similarly effective against Escherichia coli and Staphylococcus aureus at 128 and 256 μM, respectively. This study demonstrated that banana peels extracts obtained after different times affected the production of AgNPs in different manners, producing AgNPs with distinct characteristics, such as hydrodynamic diameter, Zeta potential, and polydispersity index. Moreover, all tested AgNPs showed antimicrobial activity. [ABSTRACT FROM AUTHOR]

Nature has a massive range of diverse species of flora. The phytochemical content of each plant may vary due to the diverse climate and different geographical areas. Several plants have been outlined for their reducing properties and highly exploited for the green synthesis of metal nanoparticles. Moreover, phytochemicals present in plant parts (leaf, root, flower, fruit, etc.) act as both reducing and capping agents for the production of nanoparticles. Plant-mediated nanoparticles have gained so much attention in the present era for its green and rational approach and developed as a green substitute to conventional synthesis approaches. This critical review encloses literature, phytosynthesis methods, and factors affecting the synthesis of silver nanoparticles. Also, the main characterization techniques especially, spectroscopic techniques are epigrammatically summarized and discussed here. [ABSTRACT FROM AUTHOR]

Nanobiotechnology is a fast developing scientific field having several applications in biochemistry, medicine, biology, engineering, etc. and plays a key role in the development and improvement of clean, eco-friendly, non-toxic and cost effective techniques for the synthesis and assembly of metal nanoparticles. One of the foremost green synthesis approaches includes biofabrication of silver nanoparticles (AgNPs) using plants and plant products. In the present study, we have synthesized silver nanoparticles using aqueous extract of Indian spice Asafoetida. Their formation was confirmed through UV–Vis spectral peak at 426.4 nm and their stability was also monitored for 3 months at room temperature using dynamic light scattering (DLS). DLS analysis revealed that the particles so formed were not only monodispersed in nature but also stable at room temperature for 3 months with a reported size of 90–95 nm. The characterization techniques revealed that synthesized AgNPs were well distributed with size ranging from 90 to 100 nm. Furthermore, Asafoetida-AgNPs were tested for their anticancer activity against the HepG2 cell line. Cell viability assay was done to check the percentage of viable cells and morphological changes at various test concentrations (0.01, 0.1, 1 and 10 ppm) after 24 and 48 h of exposure. The recorded viable cells at lowest concentration (0.01 ppm) was found to be 58.55% and at highest concentration (10 ppm) it was 40.08% after 24 h. Further, when the percent cell viability was observed at 48 h it was 45.22% and 20.23% at lowest and highest concentrations. Morphological characterization of HepG2 cells after the treatment of Asafoetida-AgNPs showed floating and patchy cells signifying their toxic nature against cancerous cells. [ABSTRACT FROM AUTHOR]

Thermal ecosystems like hot springs are exclusive habitat of thermotolerant microorganisms that produce exopolysaccharides (EPS). In this study, EPS produced by a hot spring origin Pseudomonas species is structurally elucidated.The EPS is highly thermostable (Td 289.98 °C), has low molecular weight (1510 Da) and is rhamnoglucose type consisting α-(1 → 3) linked to L-Rhap and α-(1 → 6) linked to d-Glc substituted with O-acetyl groups. Irregular EPS sheets with smooth surface were observed that signify the compact structure of the biopolymer; a characteristic plasticized film-like feature. Intra- and inter-molecular aggregation of EPS units are observed in atomic force microscopy. The EPS showed good rheological property at neutral pH. EPS-mediated green synthesis of silver nanoparticles (AgNP) was performed using co-precipitation method. Size of individual AgNPs had a Z-average of 93.6 nm and 0.437 polydispersity index. The EPS-coated AgNPs were moderately monodisperse. These AgNPs also exhibited biocidal property preferentially against gram negative bacteria and some fungi. Incorporating EPS to the metal nanoparticles confers them biocompatibility. Green synthesis of silver nanoparticles has gained considerable attention for its eco-friendliness in nano-medicine and nano-biotechnology. Keeping in context, the results of our study will support a new polysaccharide-mediated green synthesis approach of metal nanoparticles that shows profound antimicrobial property. [ABSTRACT FROM AUTHOR]

Increasing antimicrobial resistance is a clinical crisis worldwide. Recent progress in the field of green synthesis has fascinated scientists and researchers to explore its potentials against pathogenic microbes. Bioinspired-metal-based nanoparticles (silver, copper, gold, zinc, etc.) have been reported to be tested against both Gram-positive and Gram-negative bacteria such as B. subtilis, E. coli, Staphylococcus aureus, etc., as well as some pathogenic fungi including A. niger, F. oxysporum, A. fumigatus, etc., and are testified to exhibit inhibitory effects against pathogenic microbes. The possible modes of action of these metal nanoparticles include: (a) excess production of reactive oxygen species inside microbes; (b) disruption of vital enzymes in respiratory chain via damaging microbial plasma membranes; (c) accumulation of metal ions in microbial membranes; (d) electrostatic attraction between metal nanoparticles and microbial cells which disrupt metabolic activities; and (e) inhibition of microbial proteins/enzymes by increased production of H2O2. Although these pathways are interconnected, information on potential mechanism of most of these biogenic nanoparticles is still limited. Further exploration of these mechanisms could help in tackling the burning issue of antibiotics resistance. [ABSTRACT FROM AUTHOR]

Silver nanoparticles (AgNPs) were successfully synthesized from the reduction of Ag+ using AgNO3 solution as a precursor and Brassica rapa var. japonica leaf extract as a reducing and capping agent. This study was aimed at synthesis of AgNPs, exhibiting less toxicity with high antibacterial activity. The characterization of AgNPs was carried out using UV-Vis spectrometry, energy dispersive X-ray spectrometry, fourier transform infrared spectrometry, field emission scanning electron microscopy, X-ray diffraction, atomic absorption spectrometry, and transmission electron microscopy analyses. The analyses data revealed the successful synthesis of nano-crystalline Ag possessing more stability than commercial AgNPs. The cytotoxicity of Brassica AgNPs was compared with commercial AgNPs using in vitro PC12 cell model. Commercial AgNPs reduced cell viability to 23% (control 97%) and increased lactate dehydrogenase activity at a concentration of 3 ppm, whereas, Brassica AgNPs did not show any effects on both of the cytotoxicity parameters up to a concentration level of 10 ppm in PC12 cells. Moreover, Brassica AgNPs exhibited antibacterial activity in terms of zone of inhibition against E. coli (11.1 ± 0.5 mm) and Enterobacter sp. (15 ± 0.5 mm) which was higher than some previously reported green-synthesised AgNPs. Thus, this finding can be a matter of interest for the production and safe use of green-AgNPs in consumer products. [ABSTRACT FROM AUTHOR]

Nanotechnology has emerged as a prominent scientific discipline in the technological revolution of this millennium. The scientific community has focused on the green synthesis of metal nanoparticles as compared to physical and chemical methods due to its eco-friendly nature and high efficacy. Medicinal plants have been proven as the paramount source of various phytochemicals that can be used for the biogenic synthesis of colloidal silver and gold nanoparticles as compared to other living organisms, e.g., microbes and fungi. According to various scientific reports, the biogenic nanoparticles have shown promising potential as wound healing agents. However, not a single broad review article was present that demonstrates the wound healing application of biogenic silver and gold nanoparticles. Foreseeing the overall literature published, we for the first time intended to discuss the current trends in wound healing via biogenic silver and gold nanoparticles. Furthermore, light has been shed on the mechanistic aspects of wound healing along with futuristic discussion on the faith of biogenic silver and gold nanoparticles as potential wound healing agents. [ABSTRACT FROM AUTHOR]

Abstract: Green synthesis of silver nanoparticles-calcium alginate beads (AgNP-CA) was prepared using five different methods. The immobilization/reduction/incorporation of AgNPs on alginate biopolymer using Walsura trifoliata bark extract as reducing and capping agent were confirmed by the characterization results of UV-Vis spectra, XRD, FTIR, and TEM techniques. The prepared Ag-CA nanocomposite catalyst was used for the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) in the presence of sodium borohydride (NaBH4) in a liquid phase at ambient conditions. Comparatively, AgNPs-ACA (Adsorption calcium alginate) exhibited very high catalytic activity in the reduction of 4-nitrophenol within few seconds with exceptional stability, up to ten cycles without any loss in the catalytic activity. This study reports effective synthesis of AgNPs on alginate polymer beads via phytochemicals of aqueous extract of W. trifoliata and its excellent catalytic efficiency towards 4-nitrophenol reduction as of the practical application.Graphical Abstract: [ABSTRACT FROM AUTHOR]

Plant-derived nanomaterials opened a green approach in solving the current environment issues. Present study focused on rapid microwave-assisted synthesis and applications of gold and silver nanoparticles mediated by aqueous leaf extract of Mussaenda glabrata. The synthesized nanoparticles were characterized by UV-vis, FT-IR, powder XRD, energy-dispersive X-ray spectroscopy (EDX), transmission electron (TEM), and atomic force microscopic techniques (AFM). FCC crystal structure of both nanoparticles was confirmed by peaks corresponding to (111), (200), (220), and (311) planes in XRD spectra and bright circular spots in SAED pattern. IC values shown by gold and silver nanoparticles (44.1 ± 0.82 and 57.92 ± 1.33 μg/mL) reflected their high free radical scavenging potential. The synthesized gold and silver nanoparticles revealed their potency to inhibit pathogenic microorganisms Bacillus pumilus, Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, Aspergillus niger, and Penicillium chrysogenum. Anthropogenic pollutants rhodamine B and methyl orange were effectively degraded from aquatic environment and waste water sewages of dye industries using the prepared nanocatalysts. The catalytic capacities of the synthesized nanoparticles were also exploited in the reduction of 4-nitrophenol. [ABSTRACT FROM AUTHOR]

Green synthesis of metal nanoparticles using earth abundant materials in the absence of any toxic solvent, reducing agent and protecting group is one of the emerging areas of research in materials chemistry. Herein, we report a green method for the synthesis of silver nanoparticles (AgNPs) using Actinodaphne madraspatana Bedd leaf extract as reducing as well as stabilizing agent. To our delight, AgNPs of different sizes could be readily synthesized by simply changing the pH of plant extract and the average size of AgNPs were found to be 60, 35 and 20 nm at pH 6, 9 and 12 respectively. The efficacy of prepared AgNPs towards the catalytic reduction of 4-nitrophenol (4-NP) has been investigated and the nanocatalysts have demonstrated excellent catalytic activity as evidenced from the rate constants. The kinetics of reduction reaction follows Langmuir-Hinshelwood mechanism, based on which the rate constant ' k' was calculated. The effect of catalyst dosage, concentration of 4-NP, concentration of NaBH and size of AgNPs towards catalytic reduction of 4-NP has been systematically investigated. It was interesting to notice that the AgNPs have exhibited size dependent catalytic activity towards reduction of 4-NP and the catalytic activity was found to increase with decrease in particle size. Graphical Abstract: [ABSTRACT FROM AUTHOR]