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Silver nanoparticles (AgNPs) have been widely studied due to their interesting physicochemical properties and remarkable antibacterial properties. Chemical synthesis methods, including green chemistry, have achieved 0D nanostructures. However, ecological methods have little studied self-assembling Ag nanostructures, such as flowers or dendrites. In this work, Ag dendrites and Ag flower-like morphologies have been successfully synthesized using a one-step green method employing Arctostaphylos pungens Kunth fruit extract at room temperature. The antibacterial properties of both nanostructures were evaluated against Gram-positive Escherichia coli and Gram-negative Staphylococcus aureus bacteria. Scanning electron microscopy (SEM), X-ray diffraction (XRD), ultraviolet–visible spectroscopy (UV–Vis), and infrared spectroscopy (IR) characterized the synthesized products. The morphological changes of the nanostructures come from the variation in the concentration of the precursor salt, silver nitrate (AgNO3). A growth mechanism is proposed that includes the formation of nanospheres and their subsequent transformation into Ag dendrites. Both nanostructures show good antibacterial activity against the tested microorganisms. The Ag dendritic nanostructures presented inhibition zones of 11 mm and 10.7 mm against Escherichia coli and Staphylococcus aureus bacteria. However, the flower-like structure was slightly less effective, presenting 11 and 9.5 mm inhibition zones against the same microorganisms, respectively. [ABSTRACT FROM AUTHOR]

Delonix regia has bioactive phytochemicals present in leaves, seeds, roots, and flowers. Considering that these compounds are common in extracts used for silver nanoparticles (AgNPs) biosynthesis, this study investigated the potential of D. regia seeds aqueous extract (DRE) in different concentrations to produce AgNPs (DRE-AgNPs). DRE composition was investigated by qualitative assays, and physico-chemical/structural characterization of AgNPs was performed by UV–Visible spectroscopy, dynamic light scattering (DLS), Zeta potential, and atomic force microscopy (AFM). Antibacterial effect of DRE-AgNPs was evaluated against Escherichia coli and Staphylococcus aureus. DRE presented mainly tannins and saponins. Additionally, the absorbance of each DRE-AgNPs was positively correlated to DRE concentration. At higher DRE concentrations, AgNPs were larger, regarding Z average; tended to monodispersity; and presented more negative Zeta potentials. Hydrodynamic diameters of DRE-AgNPs were measured by number distribution and only AgNPs synthesized with DRE 2 mg ml−1 (DRE-AgNPs 2) presented a single population of particles. Thus, DRE-AgNP 2 was analyzed by AFM and exhibited a spherical shape and an average height of 18.39 ± 1.59 nm. Most of DRE-AgNPs presented antibacterial effects against E. coli and S. aureus at 128 or 256 µmol l−1. In conclusion, different DRE concentrations modulated physico-chemical characteristics of AgNPs with antibacterial activity. [ABSTRACT FROM AUTHOR]

In this study, silver nanoparticles (Ag NPs) were profitably synthesized from aqueous Amorphophallus paeoniifolius leaf extract at room temperature, using one step and eco-friend green synthesis. The leaf extract acts as reducing agent to the formation of Ag NPs from Ag+ ions. The development of Ag NPs through aqueous medium was confirmed by UV–Vis spectroscopy and the spectra show characteristic surface plasmon resonance of Ag NPs at 428 nm. Crystalline nature of the synthesized samples was affirmed by the XRD studies. The particles are predominantly grown via (111) plane of Ag crystal and the particles size was fall in the range of 20–26 nm calculated by Scheerrer's formula. Size and shape of Ag NPs were observed from the SEM and TEM characterization. The samples are almost having spherical shape particles and the size of the particles is lies between 20 and 30 nm. The energy peak at 3 keV in the EDS spectrum strongly supported that the synthesized sample is Ag. FTIR spectra exhibit the leaf extract containing various characteristic functional groups which should responsible for the reduction of Ag+ ions. Synthesized Ag NPs displayed as potential antibacterial candidate against both gram positive and gram negative bacterial. [ABSTRACT FROM AUTHOR]

The present study focused on the green synthesis of silver nanoparticles (AgNPs) using Arachis hypogaea (ground nut) root extract for the antibacterial and clinical application. The presence of major phytochemical compounds are found to be 2H-Pyaran,2,5-diethenyltetrahydro, Didodecyl phthalate, Decanoic acid, Tetradecanoic acid, Bis(2-ethylhexyl) phthalate, Dodecanoic acid, Phosphonic acid, 2-(4-Methoxyphenyl)-5-(4-methoxynaphthyl) thiophene and Methyl 2-(N-Benzylimino)-4-chloro-3,3-dimethylbutanoate by GC-MS. Nanoparticles synthesis is confirmed by UV-Vis analysis by observing the maximum absorption spectrum at 450 nm. XRD and SEM-EDX results reveals the synthesized nanoparticles are cubic crystalline with agglomerated particles of silver oxide with biomolecules present around it. TEM images clearly shows that the biosynthesized nanoparticles are mostly spherical and irregular shaped with an average particles size of 30 nm. Highest susceptibility pattern of silver nanoparticle against Enterococcus sp. (35 ± 0.4 mm) which followed by Pseudomonas sp. (33 mm) and Staphylococcus aureus (29 mm). Green synthesized nanoparticles are coated over the commercially available clinical band aid cloth by dip coating method. Silver nanoparticle incorporated band aid cloth showed good antibacterial activity against the harmful bacteria which usually cause infection and interfere during wound healing. Our findings revealed that green nanoparticle has a good antibacterial action against harmful bacteria and showed good response for efficient clinical application. [ABSTRACT FROM AUTHOR]

Compared with cultivated plants, wild weeds are cheaper and wider available for phytogenetic synthesis of nanoparticles. It is very valuable to distinguish the weed species from the local dominant wild plants for both efficient synthesis of nanoparticles and real industrial applications. In this study, a cheap, simple and novel biosynthesis method for silver nanoparticles (AgNPs) using Chenopodium aristatum. L stem extract as reducing and capping agents was developed. The real-time formation of AgNPs was monitored by UV-vis spectroscopy, and the SPR band was located at ~440 nm. The reaction factors including incubation time, AgNO concentration, reaction temperature and pH were discussed and optimized. The synthesized AgNPs were quasi-spherical with the sizes from 3 to 36 nm. HRTEM images and XRD patterns showed that the AgNPs were with the face-centered cubic (fcc) structure. FTIR spectra indicated that some functional groups such like O-H, N-H, C-H, C=O were possibly responsible for reducing silver ions into nanoparticles and acted as capping agents to avoid agglomeration. The synthesized AgNPs exhibited strong catalytic activity in degradation of 4-nitrophenol and good antibacterial activity against E. coli and S. aureus. The proposed phytogenetic synthesis method is economical, simple and feasible. [ABSTRACT FROM AUTHOR]