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Cerium oxide (CeO2) nanoparticles display excellent antioxidant properties by scavenging free radicals. However, some studies have indicated that they can cause an adverse response by generating reactive oxygen species (ROS). Hence, it is important to clarify the factors that affect the oxidant/antioxidant activities of CeO2 nanoparticles. In this work, we report the effects of different buffer anions on the antioxidant activity of CeO2 nanoparticles. Considering the main anions present in the body, Tris-HCl, sulfate, and phosphate buffer solutions have been used to evaluate the antioxidant activity of CeO2 nanoparticles by studying their DNA protective effect. The results show that CeO2 nanoparticles can protect DNA from damage in Tris-HCl and sulfate systems, but not in phosphate buffer solution (PBS) systems. The mechanism of action has been explored: cerium phosphate is formed on the surface of the nanoparticles, which interferes with the redox cycling between Ce3+ and Ce4+. As a result, the antioxidant activity of CeO2 nanoparticles is greatly affected by the external environment, especially the anions. These results may provide guidance for the further practical application of CeO2 nanoparticles. [ABSTRACT FROM AUTHOR]

The understanding of shape transformations of vesicles is of fundamental importance in biological and clinical sciences. Hyperbranched polymer vesicles (branched polymersomes) are newly emerging polymer vesicles with special structure and property. They have also been regarded as a good model for biomembranes. However, the shape transformations of hyperbranched polymer vesicles have not been studied from either an experimental or theoretical level. Herein, the shape transformations of vesicles self-assembled from amphiphilic hyperbranched multiarm copolymers (HMCs) in response to the interaction parameters between the hydrophobic core and hydrophilic arms and the polymer concentrations are investigated carefully through dissipative particle dynamics (DPD) simulations. In the morphological phase diagram, two types of vesicles are obtained: one type corresponds to vesicles without holes formed at low concentrations including unilamellar vesicles, double-lamellar vesicles, discocyte-shaped vesicles, and tubular vesicles, and the other type corresponds to vesicles with holes formed at high concentrations including stomatocyte-shaped vesicles, toroidal vesicles, genus-3 (G-3) toroidal vesicles with three holes, and genus-4 (G-4) toroidal vesicles with four holes. In addition, both the self-assembly mechanisms and the dynamics for the formation of these vesicles have been systematically studied. The current work will offer theoretical support for fabricating novel vesicles with various shapes from hyperbranched polymers.

Carboxymethyl-β-cyclodextrin (CMβ-CD)-modified glycol chitosan (GCS) nanoparticles (GCS-CMβ-CD NPs) were synthesized, and their pH-sensitive drug-release properties were investigated. GCS-CMβ-CD NPs could encapsulate doxorubicin hydrochloride (DOX), and the encapsulation efficiency and loading capacity increased with the amount of CMβ-CD. Drug-release studies indicate that DOX released was greater in acidic medium (pH 5.0) than in weakly basic medium (pH 7.4). The mechanism underlying the pH-sensitive properties of the carrier was analyzed. Finally, the MCF-7 (human breast cancer) and SW480 cell lines (human colon cancer) were used to evaluate the cytotoxicity of the NPs. The drug-loaded carriers show good inhibition of the growth of cancer cells compared with free DOX, and the carriers have good biocompatibility. In addition, the drug-loaded NPs have sustained drug-release properties. All these properties of the newly synthesized GCS-CMβ-CD NPs suggest a promising potential as an effective anticancer drug-delivery system for controlled drug release.

Cerium oxide (CeO(2)) nanoparticles display excellent antioxidant properties by scavenging free radicals. However, some studies have indicated that they can cause an adverse response by generating reactive oxygen species (ROS). Hence, it is important to clarify the factors that affect the oxidant/antioxidant activities of CeO(2) nanoparticles. In this work, we report the effects of different buffer anions on the antioxidant activity of CeO(2) nanoparticles. Considering the main anions present in the body, Tris-HCl, sulfate, and phosphate buffer solutions have been used to evaluate the antioxidant activity of CeO(2) nanoparticles by studying their DNA protective effect. The results show that CeO(2) nanoparticles can protect DNA from damage in Tris-HCl and sulfate systems, but not in phosphate buffer solution (PBS) systems. The mechanism of action has been explored: cerium phosphate is formed on the surface of the nanoparticles, which interferes with the redox cycling between Ce(3+) and Ce(4+). As a result, the antioxidant activity of CeO(2) nanoparticles is greatly affected by the external environment, especially the anions. These results may provide guidance for the further practical application of CeO(2) nanoparticles., (Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)