A. B. Shcherbakov

Nanocrystalline ceria based materials—Perspectives for biomedical application

Nanocrystalline ceria possesses a unique complex of physical and chemical properties making it highly bioactive material. In this review, modern data on the action of nanocrystalline ceria on cells, micro- and macroorganisms are analyzed. Special attention is paid to the analysis of the factors affecting protective properties of CeO2 with respect to the living systems.

Synthesis and thermal stability of nanocrystalline ceria sols stabilized by citric and polyacrylic acids

New methods are proposed for preparing aqueous sols of nanocrystalline ceria stabilized by citric or polyacrylic acid. Transmission electron microscopy and UV-Vis spectroscopy were used to study the stability of sols in hydrothermal treatment at temperatures in the range of 120–210°C.

Panthenol-stabilized cerium dioxide nanoparticles for cosmeceutic formulations against ROS-induced and UV-induced damage.

A method of panthenol-stabilized cerium dioxide nanoparticles synthesis was developed and their effect on the survival rate of human epidermoid cancer cells HEp-2 and diploid epithelial swine testicular cell line (ST-cells) under oxidative stress conditions induced by hydrogen peroxide introduction and UV irradiation was studied. The results obtained indicate that the use of panthenol as a stabilizer supposedly provides a substantial increase in the efficiency of protection. The degree of protection is determined by panthenol-to-ceria molar ratio. The combination of panthenol and nano-ceria protects biological objects under study from reactive oxygen species (ROS) and UV-irradiation more effectively than individual panthenol or ceria. The protective action of panthenol-stabilized cerium dioxide nanoparticles depends strongly on their composition and the means of their application.

Antioxidant activity of nanocrystalline ceria to anthocyanins

We study the ability of ceria nanoparticles to inhibit the oxidative degradation of anthocyanins. CeO2 nanoparticles stabilized by sodium polyacrylate or sodium citrate can substantially slow down the oxidation of anthocyanins of grapes caused by hydrogen peroxide at pH ≥ 7.0. In acid solutions, inhibition is not observed.

Inactivation of the Nitroxyl Radical by Ceria Nanoparticles

43 Cerium dioxide CeO2 nanoparticles represent a promising object for biological applications [1], which is dictated by two key factors: their high oxygen non stoichiometry [2–4] and low toxicity [5, 6]. The former factor is responsible for activity of ceria nano particles in biochemical processes, in particular, in inactivation of free radicals in a living cell, while the latter one ensures relative safety of their use in vivo. Specific properties of CeO2 nanoparticles include the ability for regeneration, in particular, over a short period of time, the nanoparticles that have partici pated in a redox process return to their initial state (as regards oxygen nonstoichiometry) [7].

Microwave-hydrothermal synthesis of gadolinium-doped nanocrystalline ceria in the presence of hexamethylenetetramine

A new method is proposed for producing nanodisperse ceria-based solid solutions, involving microwave-hydrothermal (MW-HT) treatment of aqueous solutions containing salts of cerium and dopant elements and hexamethylenetetramine (HMTA). The specifics of HMTA hydrolysis under hydrothermal conditions are studied. X-ray and electron diffraction, Raman spectroscopy, and transmission electron microscopy are used to analyze the physicochemical characteristics of Ce1 − xGdxO2 − x/2 (x = 0.10, 0.15, 0.20) nanocrystalline solid solutions produced using the new method.

Advances and prospects of using nanocrystalline ceria in cancer theranostics

This review summarizes available information on the application of nanocrystalline ceria in cancer therapy and diagnostics (theranostics). Factors responsible for the high biological activity of nanocrystalline ceria are analyzed. Principles of design of multifunctional drugs based on CeO2 are considered, and examples of their practical use are presented.

Determination of cerium(III) and cerium(IV) in nanodisperse ceria by chemical methods

Percentages of different valence cerium species have been determined in powdery samples, redispersible compositions, and aqueous sols of nanodisperse ceria prepared from cerium(IV) and cerium(III) salts by various methods with or without organic stabilizers. Cerium(III) is shown to be virtually absent in nearly all of the CeO2 samples studied. Organic stabilizers are shown to be capable of reducing cerium(IV) in aqueous CeO2 sols.

Synthesis and antioxidant activity of biocompatible maltodextrin-stabilized aqueous sols of nanocrystalline ceria

A novel method is proposed for preparing biocompatible aqueous CeO2 sols, which allows purposefully adjusting particle sizes and biochemical properties of nanocrystalline ceria (NC). The usefulness of this method for preparing aqueous sols of Ce1 − xGdxO2 − x/2 solid solutions is demonstrated. Nanocrystalline ceria has been demonstrated to have a size-dependent activity in hydroxyl radical inactivation and in protecting mouse fibroblast cells (L929) from oxidative stress induced by hydrogen peroxide administration.

Direct monitoring of the interaction between ROS and cerium dioxide nanoparticles in living cells

A method for the direct monitoring of the interaction of reactive oxygen species (ROS) with cerium dioxide nanoparticles (CDN) in living cells is proposed based on the use of a complex of calcein and CDN. The CDN–calcein complex penetrates easily into a living cell and is decomposed readily by endogenous or exogenous ROS, releasing brightly fluorescent calcein, which can be observed using conventional fluorescent microscopy. This complex is less cytotoxic than individual cerium dioxide nanoparticles and provides effective protection from oxidative stress induced by the action of hydrogen peroxide, treatment with latex beads, or infection by the vesicular stomatitis virus.