Molecular mechanism of composite nanoparticles TiO 2 /WO 3 /GO-induced activity changes of catalase and superoxide dismutase

Silicon dioxide nanoparticles adsorption alters the secondary and tertiary structures of catalase and undermines its activity

The expanding production and use of nanomaterials in various fields caused big concern for human health. Oxidative stress is the most frequently described mechanism of nanomaterial toxicity. A state of oxidative stress can be defined as the imbalance of reactive oxygen species (ROS) production and antioxidant enzyme activities. Although nanomaterials-triggered ROS generation has been extensively investigated, little is known regarding the regulation of antioxidant enzyme activities by nanomaterials. This study used two typical nanomaterials, SiO₂ nanoparticles (NPs) and TiO₂ NPs, to predict their binding affinities and interactions with antioxidant enzymes catalase (CAT) and superoxide dismutase (SOD). The molecular docking results showed that CAT and SOD had different binding sites, binding affinity, and interaction modes with SiO₂ NPs and TiO₂ NPs. The binding affinities of the two NPs to CAT were more potent than those to SOD. Consistently, the experimental work indicated NPs adsorption caused the perturbation of the second and tertiary structures of both enzymes and thus resulted in the loss of enzyme activities.

A review of tungsten trioxide (WO3)-based materials for antibiotics removal via photocatalysis

Antibiotics are extensively used in human medicine and animal breeding. The use of antibiotics has posed significant risks and challenges to the natural water environment. On a global scale, antibiotics have been frequently detected in the environment, azithromycin (254-529 ng·L^-1), ciprofloxacin (245-1149 ng·L^-1), ofloxacin (518-1998 ng·L^-1), sulfamethoxazole (1325-5053 ng·L^-1), and tetracycline (31.4-561 ng·L^-1) are the most detected antibiotics in wastewater and surface water. Abuses of antibiotics has caused a significant threat to water resources and has seriously threatened the survival of human beings. Therefore, there is an urgent need to reduce antibiotic pollution and improve the environment. Researchers have been trying to develop effective methods and technologies for antibiotic degradation in water. Finding efficient and energy-saving methods for treating water pollutants has become an important global topic. Photocatalytic technology can effectively remove highly toxic, low-concentration, and difficult-to-treat pollutants, and tungsten trioxide (WO₃) is an extremely potential alternative catalyst. Pt/WO₃ photocatalytic degradation efficiency of tetracycline was 72.82%, While Cu-WO₃ photocatalytic degradation efficiency of tetracycline was 96.8%; WO₃/g-C₃N₄ photocatalytic degradation efficiency of ceftiofur was 70%, WO_3/W photocatalytic degradation efficiency of florfenicol was 99.7%; WO₃/CdWO₄ photocatalytic degradation efficiency of ciprofloxacin was 93.4%; WO₃/Ag photocatalytic degradation efficiency of sulfanilamide was 96.2%. Compared to other water purification methods, photocatalytic technology is non-toxic and ensures complete degradation through a stable reaction process, making it an ideal water treatment method. Here, we summarize the performance and corresponding principles of tungsten trioxide-based materials as a photocatalytic catalyst and provide substantial insight for further improving the photocatalytic potential of WO₃-based materials.

Nanoparticle Effects on Stress Response Pathways and Nanoparticle-Protein Interactions

Nanoparticles (NPs) are increasingly used in a wide variety of applications and products; however, NPs may affect stress response pathways and interact with proteins in biological systems. This review article will provide an overview of the beneficial and detrimental effects of NPs on stress response pathways with a focus on NP-protein interactions. Depending upon the particular NP, experimental model system, and dose and exposure conditions, the introduction of NPs may have either positive or negative effects. Cellular processes such as the development of oxidative stress, the initiation of the inflammatory response, mitochondrial function, detoxification, and alterations to signaling pathways are all affected by the introduction of NPs. In terms of tissue-specific effects, the local microenvironment can have a profound effect on whether an NP is beneficial or harmful to cells. Interactions of NPs with metal-binding proteins (zinc, copper, iron and calcium) affect both their structure and function. This review will provide insights into the current knowledge of protein-based nanotoxicology and closely examines the targets of specific NPs.

Effects of peroxidase and superoxide dismutase on physicochemical stability of fish oil-in-water emulsion

How to maintain the physicochemical stability of oil emulsion has been one of the major challenges in food industry. Previously we reported the demulsification effects of catalase in the fish oil emulsion. In comparison, the influences of other two metal ion-containing oxidoreductases, horseradish peroxidase (HRP) and copper/zinc superoxide dismutase (SOD), on the emulsion’s stability were investigated. Submicron fish oil-in-water emulsion stabilized by polysorbate 80 was prepared by high-speed homogenization. Its physical stability was evaluated by visual and microscopic observation, turbidity and light scattering measurements, while chemical stability by the hydroperoxide content and lipid peroxidation. HRP demulsified the emulsion in a concentration-responsive manner after 3–7 days’ incubation, resulting in a decreased turbidity and significant delamination. The enlargement of oil-polysorbate droplets and protein precipitates were confirmed by size distribution and TEM observation. HRP initially elevated the emulsion’s hydroperoxide then decreased it while raising TBARS levels during 7-Day incubation. In contrary, SOD stabilized the emulsion physically and chemically. The demulsification was correspondingly attributed to the oxidation catalyzing activity of the peroxidase and the electrostatic and hydrophobic interaction between lipids and proteins. This study adds new insight to the influences of the two oxidoreductases on the stability, lipids and peroxides of food emulsions, proposes an exciting subject of elucidating the underlying mechanism.

The interaction of silica nanoparticles with catalase and human mesenchymal stem cells: biophysical, theoretical and cellular studies

Aim

Nanoparticles (NPs) have been receiving potential interests in protein delivery and cell therapy. As a matter of fact, NPs may be used as great candidates in promoting cell therapy by catalase (CAT) delivery into high oxidative stress tissues. However, for using NPs like SiO₂ as carriers, the interaction of NPs with proteins and mesenchymal stem cells (MSCs) should be explored in advance.

Methods

In the present study, the interaction of SiO₂ NPs with CAT and human MSCs (hMSCs) was explored by various spectroscopic methods (fluorescence, circular dichroism (CD), UV-visible), molecular docking and dynamics studies, and cellular (MTT, cellular morphology, cellular uptake, lactate dehydrogenase, ROS, caspase-3, flow cytometry) assays.

Results

Fluorescence study displayed that both dynamic and static quenching mechanisms and hydrophobic interactions are involved in the spontaneous interaction of SiO₂ NPs with CAT. CD spectra indicated that native structure of CAT remains stable after interaction with SiO₂ NPs. UV-visible study also revealed that the kinetic parameters of CAT such as Km, Vmax, Kcat, and enzyme efficiency were not changed after the addition of SiO₂ NPs. Molecular docking and dynamics studies showed that Si and SiO₂ clusters interact with hydrophobic residues of CAT and SiO₂ cluster causes minor changes in the CAT structure at a total simulation time of 200 ps. Cellular assays depicted that SiO₂ NPs induce significant cell mortality, change in cellular morphology, cellular internalization, ROS elevation, and apoptosis in hMSCs at higher concentration than 100 µg/mL (170 µM).

Conclusion

The current results suggest that low concentrations of SiO₂ NPs induce no substantial change or mortality against CAT and hMSCs, and potentially useful carriers in CAT delivery to hMSC.