Search

A set of cerium dioxide nanoparticles (CeO2 NPs) was synthesized by precipitation in water-alcohol solutions under conditions when the physical-chemical parameters of synthesized NPs were controlled by changing the ratio of the reaction components. The size of CeO2 NPs is controlled largely by the dielectric constant of the reaction solution. An increase of the percentage of Ce3+ ions at the surface was observed with a concomitant reduction of the NP sizes. All synthesized CeO2 NPs possess relatively high positive values of zeta-potential (ζ > 40 mV) suggesting good stability in aqueous suspensions. Analysis of the valence- and size-dependent rate of hydrogen peroxide decomposition revealed that catalase/peroxidase-like activity of CeO2 NPs is higher at a low percentage of Ce3+ at the NP surface. In contrast, smaller CeO2 NPs with a higher percentage of Ce3+ at the NP surface display a higher oxidase-like activity. [ABSTRACT FROM AUTHOR]

A rapid separation of the ten nuclearly-encoded subunits of mitochondrial cytochrome c oxidase, and ten out of the eleven subunits of cytochrome bc 1 , was achieved using a short, 50 mm C 18 -reversed-phase column. The short column decreased the elution time 4–7 fold while maintaining the same resolution quality. Elution was similar to a previously published protocol, i.e., a water/acetonitrile elution gradient containing trifluoroacetic acid. Isolated subunits were identified by MALDI-TOF. The rapidity of the described method makes it extremely useful for determining the subunit composition of isolated mitochondrial complexes. The method can be used for both analytical and micro-preparative purposes. [ABSTRACT FROM AUTHOR]

Blending carbon particles (CPs) and nanoscale bioactive cerium dioxide is a promising approach for designing composites for biomedical applications, combining the sorption and antioxidant potentials of each individual component. To address this issue, it is crucial to assess the correlation between the components' ratio, physicochemical parameters, and biofunctionality of the composites. Thus, the current research was aimed at fabricating C@CeO 2 composites with different molar ratios and the examination of how the parameters of the composites affect their bioactivity. XRD, X-ray photoelectron spectroscopy, and electron microscopy data verified the formation of C@CeO 2 composites. CeO 2 nanoparticles (NPs) of 4-6 nm are highly dispersed on the surfaces of amorphous CPs. The presence of CeO 2 NPs on the carbon surface decreased its adsorption potential in a dose-dependent manner. Besides, the coexistence of carbon and CeO 2 in a single composite promotes some redox interactions between O-functionalities and Ce 3+ /Ce 4+ species, resulting in changes in the chemical state of the surface of the composites. These observations suggest the strong connection between these parameters and the biofunctionality of the composites. The presence of CeO 2 NPs on the surface of carbon led to a significant increase in the stability of the prepared composites in their aqueous suspensions. The enhancement of bioactivity of the newly prepared C@CeO 2 compared to bare carbon and CeO 2 was validated by testing their pseudomimetic (catalase/peroxidase-like and superoxide dismutase-like), antiamyloid, and radioprotective activities.

"Core/shell" nanocomposites based on magnetic magnetite (Fe 3 O 4 ) and redox-active cerium dioxide (CeO 2 ) nanoparticles (NPs) are promising in the field of biomedical interests because they can combine the ability of magnetic NPs to heat up in an alternating magnetic field (AMF) with the pronounced antioxidant activity of CeO 2 NPs. Thus, this report is devoted to Fe 3 O 4 /CeO 2 nanocomposites (NCPs) synthesized by precipitation of the computed amount of "CeO 2 -shell" on the surface of prefabricated Fe 3 O 4 NPs. The X-ray diffraction, X-ray photoelectron spectroscopy, and high-resolution transmission electron microscopy data validated the formation of Fe 3 O 4 /CeO 2 "core/shell"-like NCPs, in which ultrafine CeO 2 NPs with an average size of approximately 3-3.5 nm neatly surround Fe 3 O 4 NPs. The presence of a CeO 2 "shell" significantly increased the stability of Fe 3 O 4 /CeO 2 NCPs in aqueous suspensions: Fe 3 O 4 /CeO 2 NCPs with "shell thicknesses" of 5 and 7 nm formed highly stable magnetic fluids with ζ-potential values of >+30 mV. The magnetization values of Fe 3 O 4 /CeO 2 NCPs decreased with a growing CeO 2 "shell" around the magnetic NPs; however, the resulting composites retained the ability to heat efficiently in an AMF. The presence of a CeO 2 "shell" generates a possibility to precisely regulate tuning of the maximum heating temperature of magnetic NCPs in the 42-50 °C range and stabilize it after a certain time of exposure to an AMF by changing the thickness of the "CeO 2 -shell". A great improvement was observed in both antioxidant and antiamyloidogenic activities. It was found that inhibition of insulin amyloid formation, expressed in IC 50 concentration, using NCPs with a "shell thickness" of 7 nm was approximately 10 times lower compared to that of pure CeO 2 . For these NCPs, more than 2 times higher superoxide dismutase-like activity was observed. The coupling of both Fe 3 O 4 and CeO 2 results in higher bioactivity than either of them individually, probably due to a synergistic catalytic mechanism.

A set of cerium dioxide nanoparticles (CeO 2 NPs) was synthesized by precipitation in water-alcohol solutions under conditions when the physical-chemical parameters of synthesized NPs were controlled by changing the ratio of the reaction components. The size of CeO 2 NPs is controlled largely by the dielectric constant of the reaction solution. An increase of the percentage of Ce 3+ ions at the surface was observed with a concomitant reduction of the NP sizes. All synthesized CeO 2 NPs possess relatively high positive values of zeta-potential ( ζ  > 40 mV) suggesting good stability in aqueous suspensions. Analysis of the valence- and size-dependent rate of hydrogen peroxide decomposition revealed that catalase/peroxidase-like activity of CeO 2 NPs is higher at a low percentage of Ce 3+ at the NP surface. In contrast, smaller CeO 2 NPs with a higher percentage of Ce 3+ at the NP surface display a higher oxidase-like activity., (© 2021 IOP Publishing Ltd.)