Superoxide dismutases (SOD) are a group of enzymes that catalyze the dismutation of superoxide (O) radicals into molecular oxygen (O) and HO as a first line of defense against oxidative stress. Here, we show that glycine-functionalized copper(ii) hydroxide nanoparticles (Gly-Cu(OH) NPs) are functional SOD mimics, whereas bulk Cu(OH) is insoluble in water and catalytically inactive. In contrast, Gly-Cu(OH) NPs form water-dispersible mesocrystals with a SOD-like activity that is larger than that of their natural CuZn enzyme counterpart. Based on this finding, we devised an application where Gly-Cu(OH) NPs were incorporated into cigarette filters. Cigarette smoke contains high concentrations of toxic reactive oxygen species (ROS, >10 molecules per puff) including superoxide and reactive nitrogen species which lead to the development of chronic and degenerative diseases via oxidative damage and subsequent cell death. Embedded in cigarette filters Gly-Cu(OH) NPs efficiently removed ROS from smoke, thereby protecting lung cancer cell lines from cytotoxic effects. Their stability, ease of production and versatility make them a powerful tool for a wide range of applications in environmental chemistry, biotechnology and medicine.
Structural features are a molybdenum-square lattice and a solid solution of iron (copper) on aluminum sites. By substitution of Al with 3d-transition metals outstanding magnetic properties are found. Typical Pauli paramagnetism is observed above a critical temperature T c ≈ 93 K. Below T c the series Al 9−x Fe x Mo 3 (0.5 < x Fe < 1) exhibits the rare coexistence of negative magnetization/diamagnetism in zero-field cooling and ferromagnetism in field-cooling mode. For Al 8.33 Fe 0.67 Mo 3 the negative magnetization is estimated to the order of ∼50% of the diamagnetic response of superconducting lead. The contribution of Fe to the magnetization is evaluated by 57 Fe Mossbauer spectroscopy in zero field and applied external fields. We show that ferromagnetic fluctuations originate from screened magnetic moments of Fe. The magnetic order presumably involves multibands originating from iron and molybdenum in the vicinity of the Fermi energy. Further insights into anomalous electron−phonon coupling are gained.
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