Sensitive chemical sensor array based on nanozymes for discrimination of metal ions and teas.

Tea, originating from China, is an important part of Chinese traditional culture. There are different qualities of and producing areas for tea on the market, therefore it is necessary to discriminate between teas in a fast and accurate way. In this study, a chemical sensor array based on nanozymes was developed to discriminate between different metal ions and teas. The indicators for the sensor array are three kinds of nanozymes mimicking laccase (Cu-ATP, Cu-ADP, Cu-AMP). The as-developed sensor array successfully discriminated 12 metal ions and the detection limit was as low as 0.01 µM. The as-developed sensor array was also able to discriminate tea samples. Different kinds of tea samples appeared in different areas in the canonical score plot with different response patterns. Furthermore, in a blind experiment, we successfully discriminated 12 samples with a 100% accuracy. This sensor array integrates chemistry and food science together, realizing the simultaneous detection of several kinds of teas using a sensitive method. The as-developed sensor array would have an application in the tea market and provide a fast and easy method to discriminate between teas.

Selenium interactions with essential and toxic elements in egg yolk from commercial and fortified eggs.

The main objective of this work was to evaluate the interaction between selenium concentration in both commercial and Se-enriched eggs and other essential/toxic elements (Ca, Mg, Fe, Zn, Pb, and Cd), taking into account a possible synergic action of iodine. Commercial eggs were purchased from several sale points or directly from the producers (farmyard eggs). Fortified eggs were obtained by supplementing chickenfeed for 6 weeks with Se as sodium selenite (1.0 microg/g Se) or Se plus iodine (1.0 microg/g Se+3.7 microg/g I). Se in experimental egg yolks significantly increased over the basic value by 39% in the Se group and 61% in the Se+I group, suggesting that I addition may enhance Se absorption. Levels of Se in commercial yolks were identical in free-range, barn or battery eggs, but significantly lower in farmyard and higher in organic eggs where the Se content approximated that found in Se fortified eggs. A significant reduction in Cd was observed in Se+I treated yolks compared to both control and Se alone diet, thus suggesting a high sensitivity of Cd to the detoxifying effect of Se combined with I. Furthermore, Se+I supplementation was associated with a significant Zn reduction, a finding which needs clarification to avoid attempts to maximize one component affecting the levels of other essential elements.

Competitive inhibition and selectivity enhancement by Ca in the uptake of inorganic elements (Be, Na, Mg, K, Ca, Sc, Mn, Co, Zn, Se, Rb, Sr, Y, Zr, Ce, Pm, Gd, Hf) by carrot (Daucus carota cv. U.S. harumakigosun).

We investigated the uptake of inorganic elements (Be, Na, Mg, K, Ca, Sc, Mn, Co, Zn, Se, Rb, Sr, Y, Zr, Ce, Pm, Gd, and Hf) and the effect of Ca on their uptake in carrots (Daucus carota cv. U.S. harumakigosun) by the radioactive multitracer technique. The experimental results suggested that Na, Mg, K, and Rb competed for the functional groups outside the cells in roots with Ca but not for the transporter-binding sites on the plasma membrane of the root cortex cells. In contrast, Y, Ce, Pm, and Gd competed with Ca for the transporters on the plasma membrane. The selectivity, which was defined as the value obtained by dividing the concentration ratio of an elemental pair, K/Na, Rb/Na, Be/Sr, and Mg/Sr, in the presence of 0.2 and 2 ppm Ca by that of the corresponding elemental pair in the absence of Ca in the solution was estimated. The selectivity of K and Rb in roots was increased in the presence of Ca. The selectivity of Be in roots was not affected, whereas the selectivity of Mg was increased by Ca. These observations suggest that the presence of Ca in the uptake solution enhances the selectivity in the uptake of metabolically important elements against unwanted elements.

[Thermodynamic approach to the selection of polyuronide sequestrants for the protection of the human body from toxic metal ions. Interactions of polyuronides with strontium and calcium ions]. / Termodinamicheskii podkhod k vyboru poliuronidnykh kompleksoobrazovatelei dlia zashchity organizma cheloveka ot toksichnykh ionov metallov. Vzaimodeistvie poliuronidov s ionami strontsiia i kal'tsiia.

Selectivity of polyuronide sequestrants (pectate, alginates of various uronide composition) in respect to Sr2+ and Ca2+ ions has been evaluated in terms of thermodynamic affinity. It is suggested that there is no point in the use of pectate as a Sr(2+)-binding agent because at initial stages of reaction it reveals higher affinity to Ca2+ ions in comparison to Sr2+ ions. Contrary to pectate, alginates under similar conditions have higher affinity to Sr2+ ions. It is shown that these ions are bound only by blocks of L-guluronic acid residues in alginate macromolecules. The results obtained lend support to the advisability of the use of alginate preparations with the high content of L-guluronic acid residues for the excretion of Sr2+ ions from human body.

[Determination of Ca, Cu, Zn, Mg, Fe, P, Ni, Mn, Mo and Ba in the secretion of Psylla Chinese Yang et Li by ICP-AES].

A method of simultaneous and direct determination of Ca, Cu, Zn, Mg, Fe, P, Ni, Mn, Mo and Ba in secretion of Psylla Chinese Yang et Li by ICP-AES is reported. The results show that the method has good precision and accuracy. The relative standard deviation is less than 5.8%. The recovery is 94%-106%. This method is also simple and rapid.

[Effect of the overload of Sr++ and Ba++ on the association of Ca+, Mg++ and Pi with total proteins (author's transl)]. / Efecto de la sobrecarga in vitro de Sr++ y Ba++ sobre la asociación de Ca++, Mg++ y Pi a proteínas totales.

The percentage of ultrafiltrable calcium, magnesium and inorganic phosphate has been determined with overload of strontium and barium in concentrations of 50 and 100 ppm. The first and the third decreased significantly, whereas magnesium did not.