It this letter, we report the study of free radicals and reactive oxygen species (ROS) generation in water solutions containing gadolinium orthovanadate GdVO4:Eu3+ nanoparticles (VNPs) and their complexes with methylene blue (MB) photosensitizer. The catalytic activity was studied under UV-Vis and X-ray irradiation by three methods (conjugated dienes test, OH· radical, and singlet oxygen detection). It has been shown that the VNPs–MB complexes reveal high efficiency of ROS generation under UV-Vis irradiation associated with both high efficiency of OH· radicals generation by VNPs and singlet oxygen generation by MB due to nonradiative excitation energy transfer from VNPs to MB molecules. Contrary to that under X-ray irradiation, the strong OH. radicals scavenging by VNPs has been observed.Electronic supplementary materialThe online version of this article (10.1186/s11671-018-2514-5) contains supplementary material, which is available to authorized users.

Nanomaterials, which promote the generation of reactive oxygen species (ROS) and precipitate the onset of oxidative stress responsible for the development of a variety of adverse conditions, have a great prospect for various nanomedicine applications. In this paper, for the first time, we report the pro-oxidant activity of GdYVO 4 :Eu 3+ and GdVO 4 :Eu 3+ nanoparticles (NPs) in water solutions without any external stimuli (in the darkness). This dark pro-oxidant activity is shown to be associated with superoxide (O 2•− ) and hydroxyl radical ( • OH) generation and is dependent on the size of NPs and, consequently, the concentration of surface defects, such as oxygen vacancies V O . For small 2 nm GdYVO 4 :Eu 3+ NPs, strong O 2•− and • OH radical production has been revealed, whereas for larger GdVO 4 :Eu 3+ NPs, low level of O 2•− and negligible level of • OH radical production have been detected during the sample storage in the darkness. The possible mechanisms of the dark ROS generation in ReVO 4 :Eu 3+ NPs are considered.

One of the tasks of current oncology is identification of cancer stem cells and search of therapeutic means capable of their specific inhibition. The paper presents the data on phenotype characteristics of Ehrlich carcinoma cells as convenient and easy-to-follow model of tumor growth. The evidence of cancer stem cells as a part of Ehrlich carcinoma and significance of CD44+ and CD44– subpopulations in maintaining the growth of this type of tumor were demonstrated. A high (tenfold) tumorigenic activity of the Ehrlich carcinoma CD44+ cells if compared to CD44– cells was proven. In this pair of comparison, the CD44+ cells had a higher potential of generating in peritoneal cavity of CD44high, CD44+CD24–, CD44+CD24+ cell subpopulations, highlighting the presence of cancer stem cells in a pool of CD44+ cells.In this study, the ability of synthesized hybrid nanocomplexes, comprising the nanoparticles of rare earth orthovanadates GdYVO4:Eu3+ and cholesterol to inhibit the tumor growth and to increase the survival of the animals with tumors was established. A special contribution into tumor-inhibiting effect is made by each of its components. Treatment of Ehrlich carcinoma cells with two-component hybrid complex resulted in maximum reduction in the concentration of the most tumorigenic CD44high cells with simultaneous rise in the number of CD117+ cells that decreased an intensity of tumor growth by 74.70 ± 4.38% if compared with the control.