The present study determined whether luteolin induces HT-29 colon cancer cell death through an antioxidant effect such as the activation of antioxidant enzymes. Luteolin decreased cell viability in human colon cancer cells (HT-29), whereas it had no effect on normal colon cells (FHC). Luteolin induced apoptosis by activating the mitochondria-mediated caspase pathway in HT-29 cells. Luteolin caused loss of the mitochondrial membrane action potential, increased mitochondrial Ca2+ level, upregulated Bax, downregulated Bcl-2, induced the release of cytochrome c from mitochondria to the cytosol, and increased the levels of the active forms of caspase-9 and caspase-3. Luteolin-induced apoptosis was accompanied by the activation of intracellular and mitochondrial reactive oxygen species scavenging through the activation of antioxidant enzymes, such as superoxide dismutase and catalase in HT-29 cells. Luteolin increased the level of reduced glutathione (GSH) and the expression of GSH synthetase, which catalyzes the second step of GSH biosynthesis. The apoptotic effect of luteolin was mediated by the activation of the mitogen-activated protein kinase signaling pathway. The present results indicate that luteolin induces apoptosis by promoting antioxidant activity and activating MAPK signaling in human colon cancer cells.

The phase transition through local strain engineering is an exciting avenue for controlling electronic, magnetic properties and catalyst activity of materials but complex phenomenon in nanoscience. Herein, we demonstrate the first combinations of bending strain and 2H/1T phase transition by rolling up MoS sheets for improving catalytic activity in relatively inert basal plane surfaces and promoting electron transfer from the less-conducting 2H MoS sheets to the electrodes. Furthermore, we generate various MoS@Pt nanoparticle hybrids nanomaterials and especially MoS@Pt scrolls containing the coverage of Pt NPs (8.3 wt%) have a high catalytic activity (39 mV per decade). The rolled up MoS@Pt sheets with bending strain (2.4%) provide an intra-layer plane gliding that allows the transversal displacement of an S plane from the 2H to the 1T phases (28%). This unique combination also allows us to maximize the intrinsic HER activity among molybdenum-sulfide based catalysts.

Controlling phase transitions through local strain engineering is an exciting avenue for tailoring the electronic and magnetic properties of materials at the nanoscale. Herein, we demonstrate a tunable semiconducting to metallic phase transition of two-dimensional transition metal dichalcogenides using strain engineering through rolled up MoS sheets (named as MoS scrolls). A phase incorporated structure for MoS nanoscrolls containing the maximum concentration of 1T phase (∼58%) with high thermal stability up to 473 K can be produced by a gliding-rolling process for the S plane. These phase transitions are irreversible by virtue of the van der Waals interaction between the layers of the nanoscrolls, which is relatively stronger than the bending strain. A high concentration of the 1T phase can tune the bandgap through temperature, and also the magnetic property from nonmagnetic to paramagnetic MoS. This study, which is able to control phase transitions by strain engineering in the field of 2D materials, proves an exciting avenue for tailoring the novel functional properties of low-dimensional materials.

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