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It was an urgent task to develop quick, cheap and accurate estrogen screen method for evaluating the estrogen effect of the booming chemicals. In this study, the voltammetric behavior between the estrogen-free and normal fragmented MCF-7 cell suspensions were compared, and the electrochemical signal (about 0.68 V attributed by xanthine and guanine) of the estrogen-free fragmented MCF-7 cell suspension was obviously lower than that of the normal one. The electrochemistry detection of ex-secretion purines showed that the ability of ex-secretion purines of cells sharp decreased due to the removing of endogenous estrogen. The results indicated that the electrochemical signal of MCF-7 cells was related to the level of intracellular estrogen. When the level of intracellular estrogen was down-regulated, the concentrations of the xanthine and hypoxanthine decreased, which led to the electrochemical signal of MCF-7 cells fall. Based on the electrochemical signal, the electrochemical estrogen screen method was established. The estrogen effect of estradiol, nonylphenol and bisphenol A was evaluated with the electrochemical method, and the result was accordant with that of MTT assay. The electrochemical estrogen screen method was simple, quickly, cheap, objective, and it exploits a new way for the evaluation of estrogenic effects of chemicals. [ABSTRACT FROM AUTHOR]

Abstract: Two electrochemical signals ascribed to xanthine/guanine and hypanthine/adenine in MCF-7 cells were detected at 0.726 and 1.053V, respectively. Based on the intensity of signals, the genistein-induced proliferation and suppression of MCF-7 cells could be evaluated. The results showed that with the increase of genistein dose at the range of 10−9 to 10−6 M, the two electrochemical signals of MCF-7 cell suspension increased due to the proliferation, whereas the tendency at the high dosage range of more than 10−5 M was decreased. The proliferation and cytotoxicity obtained by the electrochemical method were in agreement with those obtained by cell counting and the MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium] method. Thus, the two-signal electrochemical method is an effective way to evaluate the effect of drugs on cell activity based on purine metabolism. [Copyright &y& Elsevier]

In the human living environment, heavy metals and chlorpyrifos can have harmful consequences due to their complex combination. In this study, binary, ternary, and quaternary combinations of three heavy metals and chlorpyrifos in different concentrations were evaluated for their combined toxic effects using an electrochemical method, and the MTT method was used to contrast the outcomes. The combined toxic effectiveness assessed by the electrochemical CI method revealed that, except for the binary combination of cadmium chloride and chlorpyrifos, which exhibited an antagonistic effect when mixed at an equal molar ratio, lead nitrate and chlorpyrifos showed an additive effect when combined, the quaternary combination exhibited a complex transition from synergistic to additive to antagonistic effects, the other mixtures showed consistent synergistic effects. When the ratio of heavy metals in the mixture was reduced, all of them displayed synergistic effects, except for the binary mixture of cadmium chloride and chlorpyrifos, which consistently maintained an antagonistic effect, and the ternary mixture of cadmium chloride, lead nitrate, and chlorpyrifos displayed additive effects. The complex toxicity mechanisms of the mixtures do not impact the response of cellular electrochemical signals coming from the intracellular purine bases on cytotoxicity. The electrochemical approach successfully captured the various combined toxic effects of the mixture, and the outcomes were consistent with the MTT method. This method is expected to emerge as a novel approach for detecting combined toxicity. [ABSTRACT FROM AUTHOR]

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[Display omitted] • GA 3 and ICI182,780 reversely regulated the electrochemical signals of cells. • GA 3 and ICI182,780 reversely regulated intracellular purines. • GA 3 induced purine de novo synthesis by regulating PRPP amidotransferase and IMPDH. • GA 3 induced purine catabolism, mainly regulated ADA. The estrogenic effect of plant growth regulators has been received little attention, which leads to the lack of relevant toxicity data. In this study, the estrogenic effect induced by gibberellin with ERα-dependent manner was found by E-screen and western blot methods, and the electrochemical signals of MCF-7 cells regulated by gibberellin and fulvestrant were investigated. The results showed that the electrochemical signals of MCF-7 cells were increased by gibberellin, while reduced by fulvestrant significantly, and displayed an extremely sensitive response to the effects of estrogenic effect induced by ERα agonist and antagonist. Western blot results showed that the expressions of phosphoribosyl pyrophosphate amidotransferase and hypoxanthine nucleotide dehydrogenase in de novo purine synthesis and adenine deaminase in catabolism were more effective regulated by gibberellin and fulvestrant, resulting in significant changes of the levels of guanine, hypoxanthine and xanthine in cells, and then electrochemical signals. The results provide a theoretical basis for the establishment of new electrochemical detection method of the estrogenic effect of plant regulators. [ABSTRACT FROM AUTHOR]

The separation of the superimposed electrochemical signals of intracellular guanine (G) and xanthine (X) is difficult, which is great obstacle to the application of cell electrochemistry. In this paper, independent functional modules, G-functional module (G-FM) and X-functional module (X-FM), were constructed by molecular imprinting technology for sensitive detection of G and X without mutual interference, then integrated in dual-functional module cellular electrochemical sensing platform (DMCEP) as signal sensing units. DMCEP transmitted signals of G and X in cells synchronously to two windows by two signal sensing channels, and achieved the separation of superimposed signals of G and X in cells. DMCEP exhibited satisfactory reproducibility with relative standard deviation (RSD) of 3.10 and 2.22 %, repeatability with RSD of 3.72 and 3.05 % for G and X detection, and detection limit 0.05 μΜ for G and 0.06 μΜ for X. Good linear relationships between cell concentrations and the signals of G and X on DMCEP were shown in range of 0.75–85 × 106 and 3–85 × 106 cells/mL, respectively. The growth of MCF-7 cells was tracked by DMCEP, and showed consistent trend with the cell counting method, while the change of cell viability from lag to logarithmic phase captured by DMCEP was earlier than that of cell counting method. This strategy provided the foundation for the establishment of the cell viability electrochemical detection method, and new insights into the simultaneous recording of other analyses with superimposed peak positions and the simultaneous tracking of multiple biomarkers. [ABSTRACT FROM AUTHOR]

Some heavy metals in the environment may have estrogen-like activity, which probably lead to major diseases such as breast cancer. It is of great importance to establish new methods to evaluate the estrogen effect of heavy metals from multiple angles due to the complex mechanism of estrogen effect. In this paper, using MCF-7 cells as model, the electrochemical detection mechanism of the estrogen effect of heavy metal cadmium (Cd) was studied. The two electrochemical signals of MCF-7 cells derived from uric acid (0.30 V) and the mixture of guanine and xanthine (0.68 V) increased in a time and dose-dependent manner when MCF-7 cells induced by Cd, reaching the maximum at 96 h and 10−9 mol L−1. Further studies found that three purine metabolism pathways about de novo synthesis, salvage synthesis and decomposition metabolism were activated by the estrogen effect of Cd. The expression of PRPP amidotransferase in purine de novo synthesis pathway and HPRT in purine salvage synthesis pathway up-regulated, especially HPRT, which promoted cell proliferation together. Nevertheless, the expression of GDA and ADA, the key enzymes in purine decomposition metabolism pathway, up-regulated in a time and dose-dependent manner, which had same tendency with that of ERα, thereby increased the content of intracellular hypoxanthine, guanine, xanthine and uric acid, and enhanced electrochemical signals. [Display omitted] • Cd induced purine de novo and salvage synthesis, especially salvage synthesis. • Both purine de novo and salvage synthesis provided energy for cell proliferation. • Purine catabolism was induced by Cd in a time-dependent manner. • Purine metabolism induced by Cd enhanced electrochemical signals. [ABSTRACT FROM AUTHOR]

Estrogen substances in the environment are increasing dramatically, which interfere with the normal hormone level of human body, lead to the disorder of endocrine system and even cancer. It is difficult to screen a large number of environmental estrogen substances by existing estrogen effect detection methods, and the results are often affected by many factors, thus the development of new method has become an urgent task. Electrochemical method is promising to reflect cell proliferation by tracking intracellular purine bases directly. In this study, the estrogen level in MCF-7 cells on multiwall carbon nanotubes modified glassy carbon electrode (MWCNTs/GCE) could be tracked simply and conveniently, and the estrogen effect of estradiol could be reflected by electrochemistry in time and dose-dependent manners. Electrochemical method displayed the best tolerance to culture factors, such as different cell densities, serum types, culture medium types and serum estrogen-free methods, which responsed to estrogen effect higher than MTT (about 40%) and cell counting methods (about 50%). Further Western blotting analysis showed that the estrogen effect of estradiol promoted purine catabolism and up-regulated guanine deaminase (GDA) and adenine deaminase (ADA) expression, the key enzymes of purine catabolism pathway, in a dose-dependent manner. The up-regulation of GDA and ADA led to the increase of intracellular guanine and xanthine, which enhanced the electrochemical signal derived from guanine and xanthine. [Display omitted] • Electrochemistry could track estrogen level in MCF-7 cells simply and conveniently. • Electrochemistry displayed excellent environment tolerance compared to other methods. • E2 estrogen effect up-regulated GDA and ADA expression in purine catabolism pathway. [ABSTRACT FROM AUTHOR]

An in situ electrochemical method was used to assess the cytotoxicity of chlorophenols using human breast cancer (MCF-7) and cervical carcinoma (HeLa) cells as models. On treatment with different chlorophenols, the electrochemical responses of the selected cells, resulting from the oxidation of guanine and xanthine in the cytoplasm, indicated the cell viability. In addition, the in situ in vitro electrochemical method was further compared with the traditional MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assays. Although similar cytotoxicity data were obtained from both methods, the effective concentrations of chlorophenols that inhibited 50% cell growth (EC 50 values) from the electrochemical method were only slightly lower than those from the MTT assay. These results indicate that the in situ in vitro electrochemical method paves a simple, rapid, strongly responsive, and label-free way to the cytotoxicity assessment of different chlorophenol pollutants. [ABSTRACT FROM AUTHOR]

Cell viability and cytotoxicity is one of the most important toxicology indicators. In this study, an electrochemical method for detecting cell viability and cytotoxicity was discussed with the intracellular small molecule metabolite purines as indexes. The electrochemical behaviors of Balb/c 3T3, CHO, PC-12 and V79 cell suspensions were studies by cyclic voltammetry, and cell viability and cytotoxicity of four cell lines were compared by electrochemical, cell counting, 3-(4,5-dimethyl-2-Thiazyl)-2, 5-diphenyl-2H-tetrazolium bromide (MTT) and trypan blue exclusion methods. Four cell lines all showed an oxidation peak derived from mixture of xanthine and guanine at about 0.7 V. Using intracellular xanthine and guanine as index, the electrochemical method could not only describe the cell growth curves of four cell lines, but also reflect the changes of cell viability at various phases of the cell growth prior to the counting method. Compared with MTT, cell counting and trypan blue staining methods, the electrochemical method could detect the cytotoxicity of carcinogen earlier and more sensitively. The electrochemical method could track the change of intracellular xanthine and guanine contents, and used it as index to detect cell viability and cytotoxicity at the molecular level without markers, showing greater advantages over the method with apparent cell proliferation as the endpoint. [ABSTRACT FROM AUTHOR]