Carnitine palmitoyltransferase 1A promotes mitochondrial fission by enhancing MFF succinylation in ovarian cancer.

Mitochondria are dynamic organelles that are important for cell growth and proliferation. Dysregulated mitochondrial dynamics are highly associated with the initiation and progression of various cancers, including ovarian cancer. However, the regulatory mechanism underlying mitochondrial dynamics is still not fully understood. Previously, our study showed that carnitine palmitoyltransferase 1A (CPT1A) is highly expressed in ovarian cancer cells and promotes the development of ovarian cancer. Here, we find that CPT1A regulates mitochondrial dynamics and promotes mitochondrial fission in ovarian cancer cells. Our study futher shows that CPT1A regulates mitochondrial fission and function through mitochondrial fission factor (MFF) to promote the growth and proliferation of ovarian cancer cells. Mechanistically, we show that CPT1A promotes succinylation of MFF at lysine 302 (K302), which protects against Parkin-mediated ubiquitin-proteasomal degradation of MFF. Finally, the study shows that MFF is highly expressed in ovarian cancer cells and that high MFF expression is associated with poor prognosis in patients with ovarian cancer. MFF inhibition significantly inhibits the progression of ovarian cancer in vivo. Overall, CPT1A regulates mitochondrial dynamics through MFF succinylation to promote the development of ovarian cancer. Moreover, our findings suggest that MFF is a potential therapeutic target for ovarian cancer.

Mechanism of Nitrogen-Doped Ti3C2 Quantum Dots for Free-Radical Scavenging and the Ultrasensitive H2O2 Detection Performance.

MXene quantum dots feature favorable biological compatibility and superior optical properties, offering great potential for biomedical applications such as reactive oxygen species (ROS) scavenging and fluorescence sensing. However, the ROS scavenging mechanism is still unclear and the MXene-based materials for ROS sensing are still scarce. Here, we report a nitrogen-doped titanium carbide quantum dot (N-Ti3C2 QD) antioxidant with effective ROS scavenging ability. The doped nitrogen atoms promote the electrochemical interaction between N-Ti3C2 QDs and free radicals and thus enhance their antioxidant performance. Density functional theory (DFT) simulations reveal the hydroxyl radical quenching process and confirm that the doped N element promotes the free-radical absorption ability, especially for -F and -O functional groups in N-Ti3C2 QDs. Furthermore, N-Ti3C2 QDs show rapid, accurate, and remarkable sensitivity to hydrogen peroxide in the range of 5 nM-5.5 µM with a limit of detection of 1.2 nM within 15 s, which is the lowest detection limit of the existing fluorescent probes up to now. Our results provide a new category of antioxidant materials, a real-time hydrogen peroxide sensing probe, promoting the research and development of MXene in bioscience and biotechnology.

The kinetic model of cyclohexene-air combustion over a wide temperature range.

Cyclohexene is an important intermediate during the combustion process of hydrocarbon and oxygenated fuels. In view of the lack of study on the combustion of cyclohexene in air, an experimental and modeling study is performed to investigate the chemistry of cyclohexene-air mixtures under a wide temperature range. The shock tube experiments are conducted at pressures of 2 and 10 atm with equivalence ratios of 0.5, 1.0 and 2.0 to determine the ignition delay times. The ignition data under 10 atm cover a wide temperature range varying from a low temperature of 770 K to a high temperature of 1222 K. No typical negative-temperature-coefficient is observed, but the ignition at low temperatures is shorter than the extrapolation at high temperatures. A detailed kinetic model of cyclohexene oxidation is proposed based on the low temperature mechanism of 1,3-cyclohexadiene and the existing high temperature mechanism of cyclohexene. The developed model reproduces the ignition delay times in air well, but it over predicts the ignition delays in argon conditions at higher temperatures. Sensitivity analyses under different temperatures and equivalence ratios are carried out to identify the key reactions affecting ignition. The reactions of H + O2 = O + OH and hydrogen abstraction reaction of cyclohexene with oxygen (CYHEXEN + O2 = CYHEXEN-3J + HO2) explain the change of ignition delay time of cyclohexene with equivalence ratios. Flux analysis gives the change of main reaction pathways under wide temperatures and different pressures. The retro-Diels-Alder reaction as the most important consumption channel of cyclohexene at the pressure of 2 atm and temperature of 1350 K is greatly suppressed when the pressure is increased to 10 atm, while the hydrogen abstraction reaction becomes the main consumption channel of cyclohexene at the high pressure. The proposed kinetic model for cyclohexene oxidation can be used to develop models of hydrocarbon and oxygenated fuels.

Chlorine-Doped Graphene Quantum Dots with Enhanced Anti- and Pro-Oxidant Properties.

Production or elimination of highly reactive oxygen species is critical in antioxidant, photodynamic, therapeutic, and antibacterial applications. Recent studies have demonstrated that graphene quantum dots (GQDs) possess anti- and pro-oxidant properties simultaneously. However, their efficiency is low. Here, we report chlorine-doped GQDs (Cl-GQDs) with a tunable Cl doping amount and improved anti- and pro-oxidant activities. The scavenging performance and the free radical-produced efficiency of Cl-GQDs are about 7-fold and 3-fold, respectively, higher than those of the undoped GQDs. Meanwhile, Cl-GQDs are considered to be promising for antibacterial applications because of their enhanced singlet oxygen generating ability. We hope that this study could provide a new strategy to develop nanomaterials for application in the anti- and pro-oxidant field.

Optimizing oxygen functional groups in graphene quantum dots for improved antioxidant mechanism.

The development of new antioxidants with quick absorbance of free radicals and excellent biocompatibility has drawn intensive attention in recent years. Graphene quantum dots (GQDs) seemed to be one of the most promising antioxidants because of their appropriate antioxidant activity, unique structure, excellent biocompatibility, and low toxicity. However, the relatively low antioxidant activity in comparison with inorganic semiconductor materials and unclear antioxidant mechanism limited their application in cells. In this paper, we further explored their antioxidant mechanism by focusing on the relationship between antioxidant activity and surface oxygen functional groups. The total oxygen fraction was controlled by post-preparation reduction using NaBH4 and the type of oxygen functional groups was adjusted by free radicals during the preparation of GQDs. The degree of reduction and content of surface oxygen groups were determined by X-ray photoelectron spectroscopy (XPS), and the antioxidant activity was obtained by scavenging of 1,1-diphenyl-2-picryl-hydrazyl (DPPH˙) and hydroxyl (˙OH) free radicals. Based on the analysis of XPS, Raman, and Fourier-transform infrared (FT-IR) spectra, the relationship between antioxidant activity and the surface oxygen groups of GQDs was obtained, and the antioxidant mechanism of GQDs was revealed with a particular specification of each oxygen group in the antioxidant activity of GQDs, meanwhile, the biocompatibility of GQDs has been demonstrated by cytotoxicity tests. We hope that our results will provide a new insight into a complete antioxidant mechanism of GQDs.