Search

Recently the use of medicinal plants potential in the production of nanoparticles has received serious attention. Here, the main component of Camellia sinensis L. (green tea) extract was detected by spectroscopy and the optimal conditions were determined for their performance in green synthesis of silver nanoparticles at room temperature. Epigallocatechin gallate was identified as the dominant component in the extract as determined by spectroscopy, and it was established that its oxidation was a function of the solution pH. Transmission electron microscopy, dynamic light scattering, and visible absorption spectroscopy (UV‐Vis) confirmed the reduction in silver ions to silver nanoparticles (Ag NPs). Controlling over Ag NPs shape and narrow size distribution was achieved with 10 ml green tea leaf extract solution and in different reaction pH. Spherical colloidal Ag NPs with well‐defined hydrodynamic diameters (with average hydrodynamic size of 27.9–50.2 nm) were produced. Silver nitrate concentrations used in this study were lower than that of reported in similar works, and synthesis efficiency was also higher. Nanoparticles were perfectly spherical and their uniformity, compared to similar studies, was much higher. These NPs showed higher degree of stability and were aqueously stable for >10 months in dark glasses at 4°C. [ABSTRACT FROM AUTHOR]

Sphingomonas is a novel and abundant microbial resource for biodegradation of aromatic compounds. It has great potential in environment protection and industrial production. The use of microorganisms for the synthesis of nanoparticles is in the limelight of modern nanotechnology, since it is cost effective, non‐toxic and friendly to the ever‐overwhelmed environment. In this paper, the biosynthesis of silver nanoparticles (AgNPs) using Sphingomonas paucimobilis sp. BDS1 under ambient conditions was investigated for the first time. Biosynthesised AgNPs were characterised with powder ultraviolet–visible spectroscopy, X‐ray diffraction, Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy and energy dispersive X‐ray spectroscopy. The overall results revealed that well‐dispersed face centred cubic spherical AgNPs in the range of 50–80 nm were produced on the surface of Sphingomonas paucimobilis sp. BDS1, after challenging pure wet biomass with silver nitrate solution. This suggests that the capture of silver ions may be a complex process of physical and chemical adsorption and the proteins on the surface of the bacteria may play the role of reduction and stabilising agent with regard to the result of FTIR. [ABSTRACT FROM AUTHOR]

Extracellular and intracellular biosynthesis of silver nanoparticles (AgNPs) by Euglena gracilis (EG) strain and Euglena intermedia (EI) strain are reported in this study. The obtained nanoparticles showed an absorption peak approximates 420 nm in the UV–visible spectrum, corresponding to the plasmon resonance of AgNPs. According to the result of inductively coupled plasma‐atomic emission spectrometer, the intakes of silver ions by EI and EG are roughly equal. The transmission electron microscope (TEM) analysis of the successful in vivo and in vitro synthesised AgNPs indicated the sizes, ranging from 6 to 24 nm and 15 to 60 nm in diameter, respectively, and a spherical‐shaped polydispersal of the particles. The successful formation of AgNPs has been confirmed by energy dispersive X‐ray analysis connected to the TEM. The Fourier transform infrared spectroscopy measurements reveal the presence of bioactive functional groups such as amines are found to be the capping and stabilising agents of nanoparticles. To our knowledge, this is the first report where two kinds of Euglena microalga were used as the potential source for in vivo and in vitro biosynthesis of AgNPs. [ABSTRACT FROM AUTHOR]