In the study, MCF-7 human breast adenocarcinoma cells were used to study cytotoxicity of novel anticancer nanosized formulations, such as docetaxel-loaded nanoemulsion and liposomal formulation of a lipophilic methotrexate (MTX) prodrug. In vitro study of cytotoxicity was carried out in 2 models, namely using 3D in vitro model based on multicellular tumor spheroids (MTS) and 2D monolayer culture. MTS were generated by tumor cell cultivation within alginate-oligochitosan microcapsules. In the case of the monolayer culture, cell viability was found to be 25, 18 and 12% for the samples containing nanoemulsion at concentrations 20, 300 and 1000 nM of docetaxel, respectively, after 48 hs incubation. For MTS these values were higher, namely 33, 23 and 18%, respectively. Cytotoxicity of liposomal MTX prodrug-based formulation with final concentration of 1, 2, 10, 50, 100 and 1000 nM in both models was also studied. MTX liposomal formulation demonstrated lower cytotoxicity on MTS compared to intact MTX. Moreover, MTS were also more resistant to both liposomal formulation and intact MTX than the monolayer culture. Thus, at 1000 nM MTX in the liposomal form, cell viability in MTS was 1.4-fold higher than that in the monolayer culture. MTS could be proposed as a promising tool to test novel anticancer nanosized formulations in vitro.

The aging kinetics during low‐temperature aging of calcia‐stabilized tetragonal zirconia polycrystal (Ca‐TZP) ceramics prepared by high‐energy milling of natural zirconia mineral (baddeleyite) was studied by X‐ray diffraction under hydrothermal treatment conditions. Aging kinetics was investigated for ceramics with different contents of calcia. It was found that the kinetics may be well‐described within Johnson‐Mehl‐Avrami‐Kolmogorov model. Model parameters were determined by data fitting procedure. Change in exponential factor within Johnson‐Mehl‐Avrami‐Kolmogorov model with time is shown. Analytical model to describe aging kinetics is proposed. The transformation nucleation rate, initial diameter, and depth of the transformed areas and their growth rates are estimated. Degradation of hardness and fracture toughness is also reported for Ca‐TZP after low‐temperature aging for different contents of the stabilizer.

Zirconia nanofiber mats containing filaments with the average diameter of less than 100 nm were fabricated. It is found that the hardness and Young’s modulus of the mats are sensitive to the microstructure, phase composition and average diameter of the zirconia nanofibers. The hardness and Young’s modulus of the prepared zirconia nanofiber mats vary from 0.86 to 1.67 MPa and from 133 to 362 MPa, respectively, wherein an increase in hardness is accompanied by the rise in Young’s modulus.

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Wet high-energy milling and uniaxial pressing are used to fabricate CaO-stabilized tetragonal zirconia polycrystalline ceramic (Ca-TZP) with decent mechanical characteristics, i.e., a hardness of 11.5 GPa, Young’s modulus of 230 GPa, and fracture toughness of 13 MPa·m0.5. The effect of CaO concentration and the sintering temperature on phase composition and mechanical characteristics of CaO-stabilized zirconia ceramic made of baddeleyite is investigated.

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