Rational design of high-performance nanozyme is of great significance for sensing applications. Here, N-doped carbon nanocages containing Co-N x active sites (CoN x -NC) were fabricated by simple acid etching of Co@NC, which is the product of Co–Co Prussian blue analogues carbonized in an N2 atmosphere. Both optimized Co@NC-650 and CoN x -NC-650 exhibit catalase- and oxidase-like properties. They rapidly decompose H2O2 into O2 and oxidize colorless 3,3′,5,5′-tetramethylbenzidine (TMB) into a blue product. This enables them with no peroxidase-like activity. The oxidase-like activity of CoN x -NC-650 is 3.9 times that of unetched Co@NC-650. The acid treatment dissolves Co nanoparticles generated during carbonization, forming extra mesoporous structures and increasing the exposure of more Co-N x active species. The Michaelis–Menten constant for CoN x -NC-650 with a TMB substrate is 0.186 mM, which is 3.2 times lower than that of oxidase-mimicking CeO2 nanoparticles, suggesting a higher affinity to TMB. Given its excellent oxidase-like activity, the CoN x -NC-650 was used to sensitively and selectively determine acetylcholinesterase (AChE) activity based on thiocholine inhibition of the TMB color reaction. Thiocholine is produced via hydrolysis of acetylthiocholine catalyzed by AChE. The colorimetric biosensor has a linear response to AChE over 0.6–800 mU L–1 concentration range and a detection limit (3σ) of 0.2 mU L–1. The assay was successfully applied to determine AChE activity in biological samples.

No abstract

No abstract

Methylenetetrahydrofolate dehydrogenase 2 (MTHFD2) is a bifunctional enzyme located in the mitochondria. MTHFD2 has been reported to be overexpressed in several malignant tumors and is implicated in cancer development. This study aimed to investigate the effect of MTHFD2 on ovarian cancer progression. The expression of MTHFD2 was detected by bioinformatics analysis, immunohistochemistry, RT-qPCR (real-time quantitative PCR analysis) and western blot analysis.The effects of MTHFD2 depletion on cell proliferation, migration and invasion were determined through in vitro experiments. Cell cycle progression and apoptosis were accessed by flow cytometry. The related signaling pathway protein expression was determined by western blot analysis. We found thatMTHFD2 is highly expressed in both ovarian cancer tissues and cell lines. MTHFD2 deletion suppressed cell proliferation and metastasis. Knockdown of MTHFD2 induces cell apoptosis and G2/M arrest, whereas the number of cells in S phase increased with MTHFD2 overexpression. Mechanically, our results indicate that an inhibitory effect of MTHFD2 knockdown may be mediated by the downregulation of cyclin B1/Cdc2 complex and the Accepted Article FEBS Open Bio (2020) © 2020 The Authors. Published by FEBS Press and John Wiley & Sons Ltd.inhibitory effect on its activity. Additionally, MTHFD2 could regulate cell growth and aggressiveness via activation of STAT3 and the STAT3-induced epithelial-mesenchymal transition (EMT) signaling pathway. These findings indicate that MTHFD2 is overexpressed in ovarian cancer and regulates cell proliferation and metastasis, presenting an attractive therapeutic target.

In this contribution, the 2D Ni/Fe MOF nanosheets were synthesized by a simple two-step ultrasound strategy at room temperature, i.e. the 2D Ni-MOF with lamellar structure was first synthesized by...