Graphene oxide nanoflakes prevent reperfusion injury of Langendorff isolated rat heart providing antioxidative activity in situ.

Carbon materials possess powerful antioxidant activity that might be promising for the development of new generation treatment of cardiovascular diseases, ischemic conditions, and reperfusion injury. The present study aimed to characterize the structure of nanosized graphene oxide (GrO) sample and evaluate the antioxidant efficacy of GrO in situ models of oxidative stress widely used in pre-clinical studies. The structure and surface chemistry of the initial samples were analyzed via LDS, RAMAN, LDI, TPD-MS, and FTIR methods. The GrO showed a strong ability to scavenge DPPH, hydroxyl, and superoxide anion free radicals and have a total antioxidant capacity. The DFT quantum-chemical calculation demonstrated the radical scavenging effect of GrO proceeding due to the physical adsorption of the free radical on the surface. For evaluation of the antioxidant effect of GrO in situ, we used the model of ischemia-reperfusion (I/R) of Langendorff isolated rat heart. We revealed that intravenous pretreatment of Wistar male rats with GrO significantly increased resistance of myocardium to I/R, improved restoration of heart function, prevented non-effective oxygen utilization, and I/R-induced reactive oxygen species production in cardiac tissue. Thus, our data demonstrate the perspective of further use of GrO for the development of antiischemic therapy.

Asymmetric Catalysis Under 1D/2D Nanostructured Carbon Materials.

Pure enantiomers synthesis by asymmetric catalysis becomes attractive because of the high efficiency of the process that requires a very low quantity of the catalyst. Heterogenization of the chiral catalyst is an important step for its better utility, in particular, recoverability and reusability. In addition, native solid support also could accelerate the asymmetric reaction. This article focuses on 1D/2D carbon nanomaterials (CNM), in particular, single- and multi-walled carbon nanotubes and graphene as catalysts for asymmetric organic transformation. The preparation methods of CNM-based chiral catalysts and the influence of their structure and catalytic active sites on the chiral molecules synthesis are also discussed.

Morphological and chemical features of nano and macroscale carbons affecting hydrogen peroxide decomposition in aqueous media.

Chemical and structural factors of carbon materials affect their activity in adsorption and surface reactions in aqueous media. Decomposition of hydrogen peroxide studied is a probe reaction for exploring parameters of carbons that might be involved, such as specific surface area, nitrogen and oxygen doping and conformational changes. To date, a detailed comparison of the behavior of carbon nanoscale (Carbon Nanotubes, CNT, Single Layer Graphene Oxide, SLGO) with macroscale (Activated carbons, AC) materials in this reaction has not been forthcoming. Herein, we demonstrate that on their first cycle, ACs in doped and undoped forms outperform all nanoscale carbons tested in the H(2)O(2) decomposition. Among the nanocarbons, nitrogen-doped CNT exhibited the highest activity in this reaction. However, subsequent recycling of each carbon, without chemical regeneration between uses, reveals SLGO exhibits greater reaction rate stability over an extended number of cycles (n>8) than other carbons including nitrogen-doped CNT and ACs. The effects of pH, temperature and concentration on the reaction were analyzed. Quantum-chemical modeling and reaction kinetics analysis reveal key processes likely involved in hydrogen peroxide decomposition and show evidence that the reaction rate is linked to active sites with N-and O-containing functionalities.