The present study reports a green chemistry approach for the rapid and easy biological synthesis of silver (Ag), gold (Au), and bimetallic Ag/Au nanoparticles using the callus extract of Lithospermum erythrorhizon as a reducing and capping agent. The biosynthesized nanoparticles were characterized with ultraviolet-visible (UV-Vis) spectroscopy, X-ray diffraction (XRD) analysis, and transmission electron microscopy (TEM). Our results showed the formation of crystalline metal nanostructures of both spherical and non-spherical shape. Energy dispersive X-ray (EDX) spectroscopy showed the characteristic peaks in the silver and gold regions, confirming the presence of the corresponding elements in the monometallic particles and both elements in the bimetallic particles. Fourier-transform infrared (FTIR) spectroscopy affirmed the role of polysaccharides and polyphenols of the L. erythrorhizon extract as the major reducing and capping agents for metal ions. In addition, our results showed that the polysaccharide sample and the fraction containing secondary metabolites isolated from L. erythrorhizon were both able to produce large amounts of metallic nanoparticles. The biosynthesized nanoparticles demonstrated cytotoxicity against mouse neuroblastoma and embryonic fibroblast cells, which was considerably higher for Ag nanoparticles and for bimetallic Ag/Au nanoparticles containing a higher molar ratio of silver. However, fibroblast migration was not significantly affected by any of the nanoparticles tested. The obtained results provide a new example of the safe biological production of metallic nanoparticles, but further study is required to uncover the mechanism of their toxicity so that the biomedical potency can be assessed.

The probable mechanisms responsible for the accumulation of microelements in iron nodules and the particular features of this process are analyzed on the basis of experimental materials on the content

Contents, distribution, and fractionation of soil organic carbon and trace elements in soils under a green manure application | Yana Timofeeva, Lyudmila Purtova, Alexey Emelyanov, Maxim Burdukovskii, Irina Kiseleva, Marina Sidorenko | Agricultural Journals

The impact of different farming practices on changes in the properties and catalase activity of Albic Stagnosols with active iron–manganese nodule formation has been studied. The soils of unmanaged fallow with a slightly acid reaction, and the highest values of catalase activity and humus content in the upper part of the profile are close in their properties and morphology to the native soils of natural landscapes. In the soils of the phytoreclamation experiment, the influx of easily decomposable plant residues in combination with a less acidic reaction leads to an increase in the catalase activity. A high level of catalase activity is typical of horizons with the maximum content of nodules. The soils of the experimental variant with long-term application of organic fertilizer are specified by an increased stock of humus in the one-meter layer and by the lowest content of catalase. The application of mineral fertilizers is accompanied by a decrease in the humus content without significant changes in the catalase activity. The calculation of the catalase reserves coefficient, which more objectively reflects the level of enzymatic activity of the studied soils, is suggested.