Acetylcholinesterase (AChE) enzyme activity in red blood cells (RBCs) is a useful biomarker for biomonitoring of exposures to organophosphorus (OP) pesticides and chemical nerve agents. In this paper, we reported a new method for AChE activity assay based on selective immuno-capture of AChE from biological samples followed by enzyme activity assay of captured AChE using a disposable electrochemical sensor. The electrochemical sensor is based on multiwalled carbon nanotubes-gold (MWCNTs-Au) nanocomposites modified screen printed carbon electrode (SPCE), which is used for the immobilization of AChE specific antibody. Upon the completion of immunoreaction, the target AChE (including active and inhibited) is captured onto the electrode surface and followed by an electrochemical detection of enzymatic activity in the presence of acetylthiocholine. A linear response is obtained over standard AChE concentration range from 0.1 to 10 nM. To demonstrate the capability of this new biomonitoring method, AChE solutions dosed with different concentrations of paraoxon were used to validate the new AChE assay method. AChE inhibition in OP dosed solutions was proportional to OP concentration from 0.2 to 50 nM. The new AChE activity assay method for biomonitoring of OP exposure was further validated with in vitro paraoxon-dosed RBC samples. The established electrochemical sensing platform for AChE activity assay not only avoids the problem of overlapping substrate specificity with esterases by using selective antibody, but also eliminates potential interference from other electroactive species in biological samples. It offers a new approach for sensitive, selective, and rapid AChE activity assay for biomonitoring of exposure to OPs.
Lung carcinoma is the most common cancer with increasing morbidity, inefficient therapeutic modality, and poor prognosis, due to the lack of understanding of its related molecular mechanism. ZNRF3 is a newly identified negative regulator of Wnt signaling. In this study, we found that ZNRF3 level is reduced in lung carcinoma compared with normal lung tissue and its expression level is positively correlated with the survival of lung cancer patients. Restoration of ZNRF3 suppressed the proliferation and cell cycle progression of lung cancer cell lines. Suppression of ZNRF3 expression in normal lung cells increased the proliferation rates. In an animal model, ZNRF3 was shown to suppress the growth of lung cancer xenografts. ZNRF3 was shown to negatively regulate the activation of Wnt signaling in lung cancerous and normal cells. Further studies revealed that ZNRF3 is a target of miR-93, an oncogenic microRNA (miRNA) for lung cancer progression. Collectively, we found that miR-93/ZNRF3/Wnt/β-catenin regulatory network contributes to the growth of lung carcinoma. Targeting this pathway may be a promising strategy for lung cancer therapy.
Phosphorylated p53 at serine 15 (phospho-p53 15 ) is a potential biomarker of gamma-radiation exposure. In this paper, we described a new magnetic particle (MP)-based electrochemical immunoassay of human phospho-p53 15 using carbon nanospheres (NS) and protein cage nanoparticles (PCN) for signal amplification. Greatly enhanced sensitivity was achieved for three reasons: 1) PCN and the p53 15 signal antibody (p53 15 Ab 2 ) are linked to the carbon NS (PCN-p53 15 Ab 2 -NS) as a label; 2) PCN increases the amount of metal ions in the cavity of each apoferritin; 3) MPs capture a large amount of primary antibodies. Protein cage templated metallic phosphates, instead of enzymes, as multi-labels have the advantage of eliminating the addition of mediator or immunoreagents and, thus, makes the immunoassay system simpler. Subsequent stripping voltametric analysis, detected olead ions on a disposable screen-printed electrode. The response current was proportional to the phospho-p53 15 concentration in the range of 0.02 to 20 ng mL 21 with a detection limit of 0.01 ng mL 21 , which was 30-fold lower than that of the ELISA measurement of phospho-p53 15 . This method shows an acceptable stability and reproducibility and the assay results for phospho-p53 15 -spiked human serum presented good recovery rates.
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