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Developing a simple and efficient method to detect biomarkers is pivotal for early diagnosis of diseases. In this work, a novel 2D/2D heterogeneous structure, consisting of MXene-supported NiFe-based layered double hydroxide nanoflakes (denoted as MXene@NiFe-LDH), is synthesized by an in situ coprecipitation method and, for the first time, is applied as a peroxidase mimic. The results reveal that LDH nanoflakes are vertically aligned on the surface of the MXene nanosheets, forming a 2D/2D heterogeneous hybrid structure. The obtained MXene@NiFe-LDH exhibits superior peroxidase-like activity, which is attributed to the synergetic effect of the MXene and LDH phases, the large ion-accessible surface, and fast electron-transfer pathways in the nanocatalyst. Accordingly, a sensitive colorimetric sensor is proposed to detect glutathione (GSH), displaying a good linearity with GSH concentrations ranging from 0.9 to 30 μM and a low detection limit of 84 nM. The established sensor is further applied in the detection of GSH from human serum and also displays satisfying results.

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Lung cancer is the main health threat in the world. Recently, oleuropein has been reported to have potent antioxidant and anticancer activities. However, the antitumor effects of oleuropein on H1299 cells are not well understood. Therefore, the purpose of this paper is tantamount to explore the effects of oleuropein on H1299 cells and its underlying mechanism that may be involved. Oleuropein treatment in H1299 cells resulted in cell cycle distribution at G2/M arrest and apoptosis in a dose‐dependent manner. Mitochondria‐mediated apoptosis was verified by the increase in Bax/Bcl‐2 ratio, release of cytochrome c, and activation of caspase‐3 on oleuropein‐induced H1299 cells. In addition, our data also demonstrated that the p38 mitogen‐activated protein kinase (MAPK) signaling pathway has a critical role in oleuropein‐induced apoptosis. Moreover, we used transcriptome analysis to identify differentially expressed genes (DEGs) in H1299 cells by oleuropein and SB203580 treatment. Many DEGs were annotated to metabolic pathways, cell cycle, pathways in cancer, MAPK signaling pathway by Kyoto Encyclopedia of Genes and Genomes and Gene ontology enrichment methods. Network and expression analysis found that DEGs, including RPS6A5, GADD45A, and MKP, play a key role in the p38 MAPK signaling pathway. In H1299 cells, oleuropein resulted in the expression of numerous genes related to cell signaling, metabolism pathway and directly associated with apoptosis. These results illustrated that oleuropein‐induced apoptosis via mitochondrial apoptotic cascade was activated by the p38 MAPK signaling pathway in H1299 cells. Thus, oleuropein as a natural compound and therapeutic drug has potential application value in the treatment of lung cancer.