Yuri V. Malyukin

Size and shape influence of luminescent orthovanadate nanoparticles on their accumulation in nuclear compartments of rat hepatocytes

In this paper the process of nonfunctionalized negatively charged orthovanadate nanoparticle accumulation and redistribution in cells dependent on their shape and size was investigated. Aqueous colloidal solutions of nReVO4:Eu(3+) (Re=Gd, Y, La) luminescent nanocrystals of different sizes and shapes have been synthesized. The average sizes of spherical particles were 2, 20, and 300 nm, of spindle-like particles - 22×6.3 nm, and of rod-like particles - 57×4.4 nm. Luminescence of nReVO4:Eu(3+) nanocrystals was effectively excited by UV and visible irradiation. By means of luminescence microscopy and luminescence microspectroscopy, it has been revealed that spherical nanocrystals with an average diameter of 2 nm tend to accumulate mainly in the rat hepatocyte nuclei in situ and also in the isolated nuclei of these cells. An additional experiment has shown that nanoparticles reveal tropism to nuclear structural components. The penetration into nuclei does not require any modifications of the surface of nanoparticle and is governed by the shape and size of nanoparticle and also is determined by the cellular type.

Mitochondrial potential (ΔΨm changes in single rat hepatocytes: The effect of orthovanadate nanoparticles doped with rare-earth elements

Rare-earth-based nanoparticles (NPs) are widely used as fluorescent probes for imaging in vitro and in vivo. One of the challenges that restrain NPs applications in biomedical research is their effect on subcellular structures. In this paper, the ability of lanthanide NPs to affect the cellular oxidative balance and alter the mitochondrial function was analyzed. Since size and shape mutually affect the cellular internalization and intracellular distribution of NPs, the investigations were performed with NPs of spherical (GdYVO4:Eu3+, spindle-(GdVO4: Eu3+ and rod-like (LaVO4: Eu3+ shapes. Quantitative microfluorimetry with JC-1 (5,5′,6,6′-tetrachloro-1,1′,3,3′-tetraethylbenzimidazolocarbocyanine iodide) as a mitochondrial probe was used for monitoring of the mitochondrial transmembrane potential (ΔΨm) in single living cells. Changes in the ratio of the JC-1 probe fluorescence were used to analyze the NPs effect on ΔΨm. The fastest suppressive effect (within 1 hour) was found for spherical NPs. Gradual lowering of ΔΨm was observed at the exposure of cells within 24 hours for all types of NPs. Exogenous thiols were required for ΔΨm protection. The protective role of exogenous glutathione (GSH) proves that the increase of reactive oxygen species (ROS) formation with depletion of GSH can mediate NPs toxicity. The dynamics of the shape-dependent effect can be explained by the features of NPs transportation into cells.Graphical abstract

Quantum splitting in praseodymium-doped lanthanum aluminum dimetaborate crystals at X-ray excitation

ABSTRACT Mixed lanthanum-praseodymium aluminum dimetaborate and aluminum orthoborate crystals were grown. The processes of excitation energy relaxation for the crystals were compared. For praseodymium-doped lanthanum aluminum dimetaborate crystals, the effect of quantum splitting was predicted and observed experimentally: under X-ray excitation emission of two photons at 1S0 → 1D2 and 1D2 → 3H4 transitions was shown. The possibility of quantum splitting for aluminum dimetaborates can be explained by the relatively high cation-ligand distances for this lattice.

Reactive oxygen species generation in aqueous solutions containing GdVO 4 :Eu 3+ nanoparticles and their complexes with methylene blue

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.