Magnetic Nanoparticles as Effective Heavy Ion Adsorbers in Natural Samples.

This paper refers to research based on tests completed on the adsorption of heavy metal ions (Pb2+, Cu2+, Cd2+) from selected natural liquid samples such as apple, tomato, and potato juices using surface-functionalized Mn ferrite nanoparticles (Mn0.2Fe2.8O4). To determine the most efficient adsorption conditions of these heavy metals, the nanoparticles' surfaces were modified with five different ligands (phthalic anhydride, succinic anhydride, acetic anhydride, 3-phosphonopropionic acid, and 16-phosphonohexadecanoic acid). To evaluate the success of the adsorption process, the resultant liquid samples were examined for the amount of residuals using the flame atomic absorption spectroscopy method. The Mn ferrite particles selected for these tests were first characterized physicochemically by the following methods: transmission electron microscopy, scanning electron microscopy, X-ray diffraction, IR spectroscopy, Mössbauer spectroscopy.

Stability Studies of Magnetite Nanoparticles in Environmental Solutions.

In the presented paper, studies of magnetite nanoparticle stability in selected environmental solutions are reported. The durability tests were performed in four types of liquids: treated and untreated wastewater, river water, and commercial milk (0.5% fat). Nanoparticles before and after deposition in the testing conditions were measured by transmission electron microscopy, X-ray diffraction, infrared spectroscopy, and Mössbauer spectroscopy. The amount of Fe atoms transferred into the solutions was estimated on the basis of flame atomic absorption spectroscopy. The analysis of the obtained results shows good stability of the tested nanoparticles in all water solutions. They do not change their structure or magnetic properties significantly, which makes them a good candidate to be used as, for example, detectors of specific compounds or heavy metals. On the other hand, studies show that particles are stable in environmental conditions for a long period of time in an unchanged form, which can cause their accumulation; therefore, they may be hazardous to living organisms.

The Mineral Profile of Polish Beers by Fast Sequential Multielement HR CS FAAS Analysis and Its Correlation with Total Phenolic Content and Antioxidant Activity by Chemometric Methods.

Beer is the most common alcoholic beverage worldwide, and is an excellent source of macro- and microelements, as well as phenolic compounds. In this study, a fast method for the determination of Na, K, Mg, Ca, Fe, Mn, and Cu in beer was developed using flame atomic absorption spectrometry. The precision of this method was between 0.8 and 8.0% (as the relative standard deviation (RSD)), and limits of detections were in the range of 0.45 (Mn)-94 µg/L (Na). Among the macroelements tested in the beer samples, K was found at the highest concentration, whereas Na was found at the lowest concentration level. Beer also turned out to be a good source of Mg and K. The total phenolic content (TPC) was determined by the Folin-Ciocalteu method, while the antioxidant activity was estimated by the ABTS method. The results show remarkable variations in the mineral content, TPC, and antioxidant activity across the beer types and brands. Moreover, the relations between the type, color, refraction index, antioxidant activity, extract, alcohol, mineral, and the total phenolic contents were investigated using the factor analysis of mixed data (FAMD) combined with hierarchical clustering on principal components (HCPC).

Auxins and Cytokinins Regulate Phytohormone Homeostasis and Thiol-Mediated Detoxification in the Green Alga Acutodesmus obliquus Exposed to Lead Stress.

Phytohormones, such as auxins and cytokinins, take part in the integration of growth control and stress response, but their role in algal adaptation to heavy metal remains to be elucidated. The current research indicated that lead (Pb), one of the most toxic metals in nature, causes severe depletion of endogenous cytokinins, auxins, and gibberellin and an increase in abscisic acid content in the green alga Acutodesmus obliquus. Exogenous auxins and cytokinins alleviate Pb toxicity through the regulation of the endogenous phytohormones' levels. Exogenously applied auxins provoked the coordinated activation metal tolerance mechanisms leading to the increase in phytochelatin synthase activity and accumulation of phytochelatins and their precursors, which are essential for Pb sequestration. On the other hand, phytochelatin synthesis decreased in algal cells treated with cytokinins. Significant changes in the levels of low molecular weight metabolites, mainly involved in metal chelation and glutathione synthesis pathway under the influence of phytohormones in algal cells growing in the presence of Pb stress, were observed. This is the first report showing that auxins and cytokinins are important regulatory factors in algal adaptation strategies to heavy metal stress based on thiol-mediated compounds and the maintenance of phytohormone homeostasis.

Exogenously applied auxins and cytokinins ameliorate lead toxicity by inducing antioxidant defence system in green alga Acutodesmus obliquus.

The effects of auxins (IAA, IBA, PAA) and cytokinins (tZ, Kin, DPU) on the growth, oxidative damage, level of antioxidants and the activity of antioxidant enzymes as well as the contents of proteins and photosynthetic pigments in green alga Acutodesmus obliquus were investigated under 100 µM lead (Pb) stress. Heavy metal induced oxidative damage as evidenced by a decrease in cell number and reduction in the contents of proteins and chlorophylls as a consequence of an increase in reactive oxygen species (ROS) formation and lipid peroxidation. The application of exogenous auxins and cytokinins modulated biosorption of Pb by algal cells significantly alleviated the growth inhibition and stimulated the accumulation of proteins, chlorophylls and carotenes. Phytohormones also activated the xanthophyll cycle which is extensively involved in the protection of the photosynthetic apparatus in adverse environmental conditions. The reduction in oxidative stress caused by the presence of toxic Pb was observed in algal cultures treated with phytohormones. Cytokinins were more effective in lowering hydrogen peroxide and lipid peroxidation levels in comparison with auxins. This improving effect of cytokinins seems to be mediated by a decrease in Pb accumulation by algal cells, whereas auxins promoted metal uptake. Importantly, auxins and cytokinins enhanced the redox status of algal cells inducing the increase in the content of antioxidants (ascorbate, glutathione, and proline) and in the activity of antioxidant enzymes (superoxide dismutase, catalase, ascorbate peroxidase, and glutathione reductase) involved in ROS scavenging. The results of the present study strongly suggest that exogenous auxins and cytokinins enhanced the resistance of microalga A. obliquus against Pb toxicity through the activation of the antioxidant defence system.

Heavy-metal detectors based on modified ferrite nanoparticles.

In this work, we analyze artificial heavy-metal solutions with ferrite nanoparticles. Measurements of adsorption effectiveness of different kinds of particles, pure magnetite or magnetite doped with calcium, cobalt, manganese, or nickel ions, were carried out. A dependence of the adsorption efficiency on the composition of the inorganic core has been observed. Ferrites surfaces were modified by phthalic anhydride (PA), succinic anhydride (SA), acetic anhydride (AA), 3-phosphonopropionic acid (3-PPA), or 16-phosphohexadecanoic acid (16-PHDA) to compare the adsorption capability of the heavy metals Cd, Cu and Pb. The obtained nanoparticles were structurally characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and Mössbauer spectroscopy. The amounts of Cd, Cu and Pb were measured out by atomic absorption spectroscopy (AAS) and energy dispersive X-ray (EDX) as comparative techniques. The performed study shows that SA linker appears to be the most effective in the adsorption of heavy metals. Moreover, regarding the influence of the composition of the inorganic core on the detection ability, the most effective ferrite Mn0.5Fe2.5O4 was selected for discussion. The highest heavy-metal adsorption capability and universality was observed for SA as a surface modifier.