Leveraging the interplay between homogeneous and heterogeneous catalytic mechanisms: copper-iron nanoparticles working under chemically relevant tumor conditions

The present work sheds light on a generally overlooked issue in the emerging field of bio-orthogonal catalysis within tumor microenvironments (TMEs): the interplay between homogeneous and heterogeneous catalytic processes. In most cases, previous works dealing with nanoparticle-based catalysis in the TME, focus on the effects obtained (e.g. tumor cell death) and attribute the results to heterogeneous processes alone. The specific mechanisms are rarely substantiated and, furthermore, the possibility of a significant contribution of homogeneous processes by leached species –and the complexes that they may form with biomolecules- is neither contemplated nor pursued. Herein, we have designed a bimetallic catalyst nanoparticle containing Cu and Fe species and we have been able to describe the whole picture in a more complex scenario where both homogeneous and heterogeneous processes are coupled and fostered under TME relevant chemical conditions. We investigate the preferential leaching of Cu ions in the presence of a TME overexpressed biomolecule such as glutathione (GSH). We demonstrate that these homogeneous processes initiated by the released by Cu-GSH interactions are in fact responsible for the greater part of the cell death effects found (GSH, a scavenger of reactive oxygen species is depleted and highly active superoxide anions are generated in the same catalytic cycle). The remaining solid CuFe nanoparticle becomes an active catalase-mimicking surrogate able to supply oxygen from oxygen reduced species, such as superoxide anions (by-product from GSH oxidation) and hydrogen peroxide, another species that is enriched in the TME. This enzyme-like activity is essential to sustain the homogeneous catalytic cycle in the oxygen-deprived tumor microenvironment. The combined heterogeneous-homogeneous mechanisms revealed themselves as highly efficient in selectively killing cancer cells, due to their higher GSH levels compared to healthy cell lines.

Bactericidal Activity of Multilayered Hybrid Structures Comprising Titania Nanoparticles and CdSe Quantum Dots under Visible Light

Titania nanoparticle/CdSe quantum dot hybrid structures are a promising bactericidal coating that exhibits a pronounced effect against light-sensitive bacteria. Here, we report the results of a comprehensive study of the photophysical properties and bactericidal functionality of these hybrid structures on various bacterial strains. We found that our structures provide the efficient generation of superoxide anions under the action of visible light due to electron transfer from QDs to titania nanoparticles with ~60% efficiency. We also tested the antibacterial activity of hybrid structures on five strains of bacteria. The formed structures combined with visible light irradiation effectively inhibit the growth of Escherichia coli, Bacillus subtilis, and Mycobacterium smegmatis bacteria, the last of which is a photosensitive causative agent model of tuberculosis.

Unexpected benzene oxidation in collisions with superoxide anions

Superoxide anions colliding with benzene molecules at impact energies from 200 to 900 eV are reported for the first time to form massive complexes. With the aid of quantum chemistry calculations, we propose a mechanism in which a sudden double ionization of benzene and the subsequent electrostatic attraction between the dication and the anion form a stable covalently bonded C6H6O2+ molecule, that evolves towards the formation of benzene-diol conformers. These findings lend support to a model presenting a new high energy anion-driven chemistry as an alternative way to form complex molecules.

Separable Magnetic Fe3O4@MoS2 Composite for Adsorption and Piezo-Catalytic Degradation of Dye

Well-designed composite catalysts are of increasing concern due to their improved performance compared to individual components. Herein, we designed and synthesized an Fe3O4@MoS2 composite via a simple hydrothermal method. As for the resultant composite, the MoS2 nanolayers presented a novel piezo-catalytic effect, while the Fe3O4 core provided a magnetic separation property. The structure and properties of Fe3O4@MoS2 were determined by relevant experiments. It was found that Fe3O4@MoS2 exhibited enhanced piezo-catalytic degradation of rhodamine B and good magnetic recovery/recycling features. The kobs for rhodamine B degradation over Fe3O4@MoS2 was 0.019 min−1—a little longer than that over MoS2 (0.013 min−1). Moreover, Fe3O4@MoS2 also showed a favorable ability to adsorb rhodamine B in solution, with a saturation adsorption of 26.8 mg/g. Further studies revealed that piezo-electrons, holes, and superoxide anions were key species in the piezo-catalytic degradation of rhodamine B. Notably, the step where oxygen trapped electrons to produce superoxide anions had a significant impact on the degradation of the dye. This work, not limited to the development of a high-performance MoS2-based piezo-catalyst, is expected to provide new insights into the working mechanisms and process profiles of composite piezo-catalysts.

Anti-Helicobacter pylori Activity of a Lactobacillus sp. PW-7 Exopolysaccharide

Helicobacter pylori is a cause of gastric cancer. We extracted the exopolysaccharide (EPS) of Lactobacillus plajomi PW-7 for antibacterial activity versus H. pylori, elucidating its biological activity and structural characteristics. The minimum inhibitory concentration (MIC) of EPS against H. pylori was 50 mg/mL. Disruption of the cell membranes of pathogenic bacteria by EPS was indicated via the antibacterial mechanism test and confirmed through electron microscopy. EPS also has antioxidant capacity. The IC50 of EPS for 2,2-Diphenyl-1-picrylhydrazyl (DPPH) radical, superoxide anions, and hydroxyl radicals were 300 μg/mL, 180 μg/mL, and 10 mg/mL, respectively. The reducing power of EPS was 2 mg/mL, equivalent to 20 μg/mL of ascorbic acid. EPS is a heteropolysaccharide comprising six monosaccharides, with an approximate molecular weight of 2.33 × 104 Da. Xylose had a significant effect on H. pylori. EPS from L. plajomi PW-7 showed potential as an antibacterial compound and antioxidant, laying a foundation for the development of EPS-based foods.

PARAQUAT INDUCED BILATERAL SPONTANEOUS PNEUMOTHORAX-DAISLEY BARTON SYNDROME – A CASE REPORT

Paraquat (1,1-dimethyl-4, 4-bipyridylium dichloride) is an effective herbicide which is widely used all over the world and India is no exception. It is toxic to humans due to its redox activity which produces superoxide anions. Accidental or suicidal poisoning causes ulceration over the mouth and gastrointestinal tract and the majority of patients die of acute renal failure, hepatic failure and acute lung injury causing mainly lung brosis and consolidation. Treatment of paraquat poisoning is extremely difcult as it does not have any specic antidote. Treatment is mainly symptomatic. Very few patients may develop spontaneous pneumothorax, known as Daisley Barton syndrome, which further impairs survival of the patient Here we present a patient of paraquat induced spontaneous bilateral pneumothorax who survived with conservative treatment.

The application prospect of metal/metal oxide nanoparticles in the treatment of osteoarthritis

The current understanding of osteoarthritis is developing from a mechanical disease caused by cartilage wear to a complex biological response involving inflammation, oxidative stress and other aspects. Nanoparticles are widely used in drug delivery due to its good stability in vivo and cell uptake efficiency. In addition to the above advantages, metal/metal oxide NPs, such as cerium oxide and manganese dioxide, can also simulate the activity of antioxidant enzymes and catalyze the degradation of superoxide anions and hydrogen peroxide. Degrading of metal/metal oxide nanoparticles releases metal ions, which may slow down the progression of osteoarthritis by inhibiting inflammation, promoting cartilage repair and inhibiting cartilage ossification. In present review, we focused on recent research works concerning osteoarthritis treating with metal/metal oxide nanoparticles, and introduced some potential nanoparticles that may have therapeutic effects.

Cadmium Accumulation Involves Synthesis of Glutathione and Phytochelatins, and Activation of CDPK, CaMK, CBLPK, and MAPK Signaling Pathways in Ulva compressa

In order to analyze the effect of cadmium in Ulva compressa (Chlorophyta), the alga was cultivated with 10, 25, and 50 μM of cadmium for 7 days, and the level of intracellular cadmium was determined. Intracellular cadmium showed an increase on day 1, no change until day 5, and an increase on day 7. Then, the alga was cultivated with 10 μM for 7 days, and the level of hydrogen peroxide, superoxide anions, and lipoperoxides; activities of antioxidant enzymes ascorbate peroxidase (AP), dehydroascorbate reductase (DHAR), and glutathione reductase (GR); the level of glutathione (GSH) and ascorbate (ASC); and the level of phytochelatins (PCs) and transcripts encoding metallothioneins (UcMTs) levels were determined. The level of hydrogen peroxide increased at 2 and 12 h, superoxide anions on day 1, and lipoperoxides on days 3 to 5. The activities of AP and GR were increased, but not the DHAR activity. The level of GSH increased on day 1, decreased on day 3, and increased again on day 5, whereas ASC slightly increased on days 3 and 7, and activities of enzymes involved in GSH and ASC synthesis were increased on days 3 to 7. The level of PC2 and PC4 decreased on day 3 but increased again on day 5. The level of transcripts encoding UcMT1 and UcMT2 increased on days 3 to 5, mainly that of UcMT2. Thus, cadmium accumulation induced an oxidative stress condition that was mitigated by the activation of antioxidant enzymes and synthesis of GSH and ASC. Then, the alga cultivated with inhibitors of calcium-dependent protein kinases (CDPKs), calmodulin-dependent protein kinases (CaMKs), calcineurin B-like protein kinases (CBLPKs), and MAPKs and 10 μM of cadmium for 5 days showed a decrease in intracellular cadmium and in the level of GSH and PCs, with the four inhibitors, and in the level of transcripts encoding UcMTs, with two inhibitors. Thus, CDPKs, CaMK, CBLPKS, and MAPKs are involved in cadmium accumulation and GSH and PC synthesis, and GSH and PCs and/or UcMTs may participate in cadmium accumulation.