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Cerium oxide nanoparticles present an interesting material for different industrial applications in biotechnology and medicine. The CeO2 nanopowder was produced by the method of pulsed electron evaporation of ceramic oxide targets with condensation of the vapors in a low pressure gas. The modification of nanoparticle surface was made with sodium citrate and N-phosphonomethylaminodiacetic acid. The stable aqueous suspensions of CeO2 nanoparticles could not be obtained in the work. This is probably due to the high hydrophobic properties of the nanoparticle surface. The cerium oxide nanoparticles with different stabilizers exhibit luminescence properties.Cerium oxide nanoparticles present an interesting material for different industrial applications in biotechnology and medicine. The CeO2 nanopowder was produced by the method of pulsed electron evaporation of ceramic oxide targets with condensation of the vapors in a low pressure gas. The modification of nanoparticle surface was made with sodium citrate and N-phosphonomethylaminodiacetic acid. The stable aqueous suspensions of CeO2 nanoparticles could not be obtained in the work. This is probably due to the high hydrophobic properties of the nanoparticle surface. The cerium oxide nanoparticles with different stabilizers exhibit luminescence properties.

Acidification of the extracellular matrix, an intrinsic characteristic of many solid tumors, is widely exploited for physiologically triggered delivery of contrast agents, drugs, and nanoparticles to tumor. However, pH of tumor microenvironment shows intra- and inter-tumor variation. Herein, we investigate the impact of this variation on pH-triggered delivery of magnetic nanoparticles (MNPs) modified with pH-(low)-insertion peptide (pHLIP). Fluorescent flow cytometry, laser confocal scanning microscopy and transmission electron microscopy data proved that pHLIP-conjugated MNPs interacted with 4T1 cells in two-dimensional culture and in spheroids more effectively at pH 6.4 than at pH 7.2, and entered the cell via clathrin-independent endocytosis. The accumulation efficiency of pHLIP-conjugated MNPs in 4T1 tumors after their intravenous injection, monitored in vivo by magnetic resonance imaging, showed variation. Analysis of the tumor pH profiles recorded with implementation of original nanoprobe pH sensor, revealed obvious correlation between pH measured in the tumor with the amount of accumulated MNPs.

New fluorescent thiazoles were designed and synthesized based on a 3-aryl-2-(thiazol-2-yl)acrylonitrile core. Three synthetic approaches were developed to introduce specific combinations of substituents at the 2-, 4- and 5-thiazole positions. The obtained thiazolyl-2-acrylonitriles exhibited a wide range of fluorescent colours (from green to red), long wavelength maxima and intensity depending on the combination of the substituents located at rings A, B and C. The expanded photophysical investigation established the best substituent combinations to increase their emission. Absorption and emission were studied in solvents with different polarities, as well as in DMSO-water and dioxane-water mixtures. The thiazoles showed multifunctional properties and exhibited good emission in the solid phase and in suspension (aggregation induced enhancement emission/AIEE effect). Photophysical investigations revealed a large Stokes shift, significant positive solvatochromism, and the tunability of the colour and intensity. Sharp strengthening of the emission intensity of the thiazoles was observed upon stimulation with some acid (H2SO4 and BF3·OEt2) in solvents and in the solid phase (HCl). State-of-the-art quantum mechanical calculations were performed to interpret the experimental findings. Biological experiments revealed the good penetration of the thiazoles into living cells and the accumulation both in lysosomes and, to a lesser extent, near membranes.

Hybrid nanoparticles based on Fe3O4 and CdS combining magnetic and luminescence properties were synthesized. The possibility of visualization of various cells by 3-mercaptopropylsilane-modified CdS nanoparticles and hybrid nanoparticles based on them using a confocal microscope was demonstrated. The synthesized materials did not show a clear-cut cytotoxicity.

To enlarge the highly active fluorophore family of small molecular heterocycles, we present an effective strategy for the synthesis of novel 2-aryl-1,2,3-triazol-4-carboxylic acids (ATAs). The behavior of ATAs in different solvents showed that these new 1,2,3-triazole derivatives had bright blue fluorescence with excellent quantum yields, large Stokes shifts, and prolonged fluorescence lifetimes. Their photophysical and physicochemical properties showed extra sensitivity to both structural changes and the microenvironment, usually accompanied by marked changes in quantum yield. The responses of the ATAs to varying pH were different depending on the structure of the amino group at the triazole ring C5 atom. pKa values of 7.65–8.08 were obtained for ATAs bearing a tert-amino group. In contrast, the pKa values of ATAs bearing secondary alkylamines were in the range of 3.20–3.52. Quantum mechanical methods were employed to understand the underlying transitions and explain the obtained experimental data. Among the synthesized compounds, aggregation-induced emission enhancement (AIEE) behavior was observed, with potential applications as sensors for monitoring and controlling pH. The reversibility of ATAs between acid and alkaline pH values, as well as their toxicity, supports their real-time use in biological research.

The efficiency of magnetic labeling with L-Lys-modified Fe3O4 magnetic nanoparticles (MNPs) and the stability of magnetization of rat adipose-derived mesenchymal stem cells, lineage-negative (Lin(-)) hematopoietic progenitor cells from mouse bone marrow and human leukemia K562 cells were studied. For this purpose, covalent modification of MNPs with 3-aminopropylsilane and N-di-Fmoc-L-lysine followed by removal of N-protecting groups was carried out. Since the degree of hydroxylation of the surface of the starting nanoparticles plays a crucial role in the silanization reaction and the possibility of obtaining stable colloidal solutions. In present work we for the first time performed a comparative qualitative and quantitative evaluation of the number of adsorbed water molecules and hydroxyl groups on the surface of chemically and physically obtained Fe3O4 MNPs using comprehensive FTIR spectroscopy and thermogravimetric analysis. The results obtained can be further used for magnetic labeling of cells in experiments in vitro and in vivo.

High-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD) analysis, electron paramagnetic resonance (EPR), X-ray absorption spectroscopy (XAS), magnetic methods, and density-functional theory (DFT) calculations were applied for the investigations of Co-doped anatase TiO2 nanoparticles ( ∼ 20 nm). It was found that high-spin Co2+ ions prefer to occupy the interstitial positions in the TiO2 lattice which are the most energetically favourable in compare to the substitutional those. A quantum mechanical model which operates mainly on two types of Co2+ – Co2+ dimers with different negative exchange interactions and the non-interacting paramagnetic Co2+ ions provides a satisfactorily description of magnetic properties for the TiO2:Co system.

This study presents the synthesis and optical properties of a new class of bright green-yellow fluorescent dyes with potential applications in bioimaging. A facile synthetic route via the chelation of aryl(hetaryl)aminoacryloylthiophene scaffolds with a BF2 fragment is presented. The photophysical properties of the dyes are attributed to the nature and position of electron-donating and electron-withdrawing substituents. Upon coordination to a BF2 fragment, characteristic emission was observed, with λem ranging from 503 to 543 nm and quantum yields of 0.14-0.42. Compared with parent aryl(hetaryl)aminoacryloylthiophenes, a significant red shift in absorption (up to 480 nm in solution) and emission (up to 543 nm in solution and 610 nm in the solid state) and high chemical stability and photostability were observed. The electron-accepting character of the substituents on the terminal aromatic ring or replacing this fragment with pyridine or pyrazine moieties resulted in increased quantum yields. To gain insight into the electronic structures and optical properties, quantum mechanical calculations were performed. The results of (TD-)DFT calculations supported the structural and spectroscopic data and showed the features of electronic distribution in the frontier molecular orbitals and active electrophilic and nucleophilic sites in the compounds investigated. Synthesized BF2 complexes are promising dyes for cell imaging and flow cytometry owing to their ready penetration and accumulation in cells.

The surface modification of Fe

IR absorption and magnetic data for the titanium dioxide nanopowders are studied. Additional absorption in IR range is revealed in nanocrystalline TiO2 and Co-doped TiO2 after reducing annealing and explained by appearance of the oxygen vacancies and delocalised charge carriers. Increasing of the absorption in IR range after annealing of Co-doped TiO2 in vacuum (or decreasing of this contribution after annealing in air) correlates with arising (or vanishing) of ferromagnetic contribution. © 2018 The Authors, published by EDP Sciences. This work was supported by the Russian Scientific Foundation, Grant No. 16-12-10004.