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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]

The green synthesis of silver nanoparticles (AgNPs) has been proposed as a simple, eco-friendly and cost effective alternative to chemical and physical methods. The Rhus chinensis plant is one of the well studied medicinal plant and its galls find excellent clinical and therapeutic applications. The present study reports the use of water extract from galls of R. chinensis as a reducing agent and formation of AgNPs from silver nitrate solution by a green synthesis route. The AgNPs formation was observed visually by color change and the absorbance peak at 450 nm was observed by UV-Visible spectrophotometer. The shape, size, and morphology of synthesized AgNPs were monitored by transmission electron microscopy and field-emission scanning electron microscopy. The face centered cubic structure of AgNPs was confirmed by X-ray diffraction pattern and element composition by energy dispersive X-ray analysis. The Fourier transform infrared spectroscopy spectrum revealed that the presence of components acts as a reducing and capping agent. The antibacterial activity was performed using the agar well diffusion method. Minimum inhibitory concentration and minimum bactericidal concentration were determined by broth dilution and spread plate method respectively. Synthesized nanoparticles were spotted as triangular and hexagonal shape and the particle size was around 150 nm. [ABSTRACT FROM AUTHOR]