1.
Highly sensitive colorimetric detection of glucose through glucose oxidase and Cu2+-catalyzed 3,3',5,5'-tetramethylbenzidine oxidation.
Li, X, Gao, L, Chen, Z
Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy. 2019;:37-41
Abstract
We develop a glucose oxidase (GOx)-mediated strategy for detecting glucose based on oxidized 3,3',5,5'-tetramethylbenzidine (oxTMB), which is generated from Cu2+-catalyzed 3,3',5,5'-tetramethylbenzidine (TMB)-H2O2 reaction, as colorimetric readout. The sensing system involves two processes: generation of H2O2 from GOx-catalyzed oxidation of glucose, and H2O2-induced the oxidization of TMB via the catalysis of Cu2+. The H2O2 formed by GOx-catalyzed oxidation of glucose oxidizes colorless TMB to blue oxTMB, thus enhancing the absorbance intensity at 670 nm. Therefore, we draw a conclusion that the enhancement in colorimetric signal relies directly on H2O2 concentration, which, in turn, depends on glucose concentration. This color change can be used not only for visual detection of glucose by naked eyes but for reliable glucose quantification in the range from 1 to 100 nM with a detection limit of 0.21 nM. The method possesses the following advantages: simple design, low experimental cost, and no any additional experimental equipment for heating, illuminating, or bubbling.
2.
Structure and anticancer activities of four Cu(ii) complexes bearing tropolone.
Mo, X, Chen, Z, Chu, B, Liu, D, Liang, Y, Liang, F
Metallomics : integrated biometal science. 2019;(11):1952-1964
Abstract
Agents inducing apoptosis and autophagic death could be effective chemotherapeutic drugs. In this work, four novel Cu(ii) complexes formulated as [CuL2] (1), [Cu(phen)LCl]·0.5H2O (2), [Cu2(MQ)2L2] (3) and [Cu(2,2'-bpy)LCl]·H2O (4) (phen = 1,10-Phenanthroline, HMQ = 8-hydroxy-2-methylquinoline, 2,2'-bpy = 2,2'-bipyridine) were prepared from the reactions of copper(ii) chloride with tropolone (HL) in the absence or presence of different ancillary ligands. The solution state structures of 1, 2 and 4 agree well with their solid state structures. Complex 3 presents a dimer structure in the solid state, however, a monomer structure in the solution state. It was shown that all of these complexes are stable under experimental conditions and bind to DNA in an intercalative mode with the binding constant Kb values of 1.05 × 103, 2.57 × 103, 2.53 × 103 and 2.26 × 103 L mol-1 for complexes 1, 2, 3 and 4, respectively. The anti-proliferative tests against cultured human cancer cell lines (A549, Bel-7402, MGC80-3, T24, SK-OV-3, and NCI-H460) in vitro revealed cytotoxic activities for these complexes, which are much better than those for all ligands in these complexes, as well as that for cis-platin. After a careful comparison, the cytotoxic activity of complex 2 against MGC80-3 cells in vitro (IC50 = 3.5 ± 0.9 μM for 2 and 18.0 ± 1.2 for cis-platin) was further investigated in detail as an example. 2 induces the apoptosis of MGC80-3 through a caspase-dependent mitochondrion pathway and can also induce autophagy, which revealed a certain anticancer activity for complex 2.
3.
Iron supplementation does not affect copper and zinc absorption in breastfed infants.
Domellöf, M, Hernell, O, Abrams, SA, Chen, Z, Lönnerdal, B
The American journal of clinical nutrition. 2009;(1):185-90
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Abstract
BACKGROUND Iron supplements are commonly recommended for infants but were suggested to inhibit zinc and copper absorption. OBJECTIVE The objective of this study was to investigate potential effects of iron supplementation, infant age, and mineral status on zinc and copper absorption in infants at 6 and 9 mo of age. DESIGN Twenty-five healthy breastfed term infants were recruited from a larger randomized iron supplementation trial. Six of these infants received iron supplements (1 mg . kg(-1) . d(-1)) from 4 to 9 mo, 8 were supplemented from 6 to 9 mo, and 11 received placebo only. Zinc and copper absorption was measured at 6 and 9 mo of age, using orally administered (70)Zn and (65)Cu and fecal monitoring of recovered stable isotopes. RESULTS Mean (+/-SD) zinc absorption was 51.9 +/- 17.9%, and mean copper absorption was 79.0 +/- 13.5%. No significant difference was observed in zinc or copper absorption between 6 and 9 mo of age. When combining all measurements, no significant effect of prior iron supplementation was observed on zinc or copper absorption. No significant correlation was observed between plasma zinc and zinc absorption or between plasma copper and copper absorption. No significant correlation was observed between erythrocyte copper-zinc-dependent superoxide dismutase activity and copper absorption. CONCLUSIONS The study does not support the contention that iron supplements inhibit the absorption of zinc or copper in healthy breastfed infants at 6-9 mo of age. In addition, we did not find any age-related changes in zinc or copper absorption between 6 and 9 mo of age.
4.
Using elevated carbon dioxide to enhance copper accumulation in Pteridium revolutum, a copper-tolerant plant, under experimental conditions.
Zheng, J, Wang, H, Li, Z, Tang, S, Chen, Z
International journal of phytoremediation. 2008;(2):159-70
Abstract
In our survey in the copper (Cu) mining area of China, a sun fern (Pteridium revolutum) was found to accumulate 30-567 mg Cu kg(-1) DW (33 samples) in its fronds with a large frond biomass. Cu translocation factors in the plants varied from 0.09 to 3.88. In a greenhouse pot experiment, the effect of an elevated CO2 concentration (700 microL L(-1)) on Cu accumulation in plants was studied using three fern species (P. revolutum, Pteridium aquilinum, and Pteris vittata) grown in the Cu-contaminated soil. P. revolutum showed a higher Cu tolerance but its Cu translocation factor was lower than 1. At the elevated CO2 concentration, frond biomass of all species was significantly increased, as was the total Cu content in the fronds of P. revolutum and P. aquilinum. Our study suggests that P. revolutum could serve as a good candidate for phytoextraction of Cu-contaminated soils and that doubling the ambient CO2 concentration will facilitate its use in phytoextraction.