Determining superoxide dismutase content and catalase activity in mammalian cell lines

Traditional methods for determining superoxide dismutase (SOD) content and catalase (CAT) activity rely on measuring the absorbance of individual tissue (biological) samples using a cuvette and spectrophotometer, rather than cell cultures. Although there are kits available for SOD and CAT assays, these allow for high-throughput analysis of samples and might be too expensive for research laboratories in countries from the Global South, such as South Africa. This paper describes a simple and cost-effective method to determine SOD content and CAT activity in mammalian cell cultures following exposure to environmental chemical mixtures by measuring absorbance in 96-well microplates. Moreover, the equipment used for this method is considered standard for cell culture laboratories, while the reagents and consumables are easily obtainable.•Antioxidant enzyme levels can be measured in vitro in cell cultures.•The supernatant obtained can be used to determine protein concentration, SOD content, and CAT activity.•This method is simple and affordable, allowing for the analysis of multiple samples (up to 32 samples per microplate).

Understanding the nature of Fenton processes in soil matrices: The role of iron forms and organic matter

Understanding the processes of pollutants removal in soil remediation practices is crucial to apply the appropriate treatment method. Although widely employed in soil contamination events, the mechanisms of the Fenton reaction are still debatable. To investigate the catalytic performance of soils towards the degradation of p-xylene in Fenton reactions, we performed a series of experiments employing two soil samples with different physical-chemical properties, Oxisol and Alfisol. These soils were subjected to extraction procedures that separated the different types of pedogenic iron oxides (amorphous and crystalline) and produced soil fractions with different organic matter contents. We observed that Oxisol, which contains high amounts of amorphous pedogenic iron oxides, performed better in hydrogen peroxide decomposition and radical generation but worse in p-xylene degradation. These results originated from the presence of hematite in Oxisol, which has a lower catalytic activity than goethite, the pedogenic oxide present in Alfisol. Samples containing high concentrations of organic matter performed better in decomposing hydrogen peroxide but worse in degrading p-xylene due to the scavenging of active species by labile organic matter compounds.

Molybdenum disulfide nanosheets vertically grown on self-supported titanium dioxide/nitrogen-doped carbon nanofiber film for effective hydrogen peroxide decomposition and "memory catalysis"

A self-supporting catalyst consisting of 1D/2D vertical molybdenum disulfide@titanium dioxide/nitrogen-doped carbon nanofiber (MoS₂@TiO₂/NCNFs) was prepared and tested. It showed efficient hydrogen peroxide (H₂O₂) decomposition to generate hydroxyl radical (OH) and degradation of various pollutants under solar irradiation. The contribution of the increase in MoS₂ edges for decomposing H₂O₂ was 0.0698 min^-1. That is 9.83 times the rate of the original MoS₂ edges resulting from the vertical structure. Specially, the catalyst degraded various aromatic pollutants even in the dark by releasing electrons stored in its graphite component to realize "memory catalysis". Also, it exhibited high degradation efficiency under outdoor solar irradiation. The catalyst was easily separated from the treated water, avoiding complex separation processes. All these features suggest this catalyst has great potential in practical water and sewage treatment applications.

Catalytic performance of carbon nanotubes in H2O2 decomposition: experimental and quantum chemical study

The catalytic performance of multi-walled carbon nanotubes (MWCNTs) with different surface chemistry was studied in the decomposition reaction of H2O2 at various values of pH and temperature. A comparative analysis of experimental and quantum chemical calculation results is given. It has been shown that both the lowest calculated activation energy (∼18.9 kJ/mol) and the highest rate constant correspond to the N-containing CNT. The calculated chemisorption energy values correlate with the operation stability of MWCNTs. Based on the proposed quantum chemical model it was found that the catalytic activity of carbon materials in electron transfer reactions is controlled by their electron donor capability.