Olga A. Inozemtseva

Liposomes loaded with hydrophilic magnetite nanoparticles: Preparation and application as contrast agents for magnetic resonance imaging

Magnetic fluid-loaded liposomes (MFLs) were fabricated using magnetite nanoparticles (MNPs) and natural phospholipids via the thin film hydration method followed by extrusion. The size distribution and composition of MFLs were studied using dynamic light scattering and spectrophotometry. The effective ranges of magnetite concentration in MNPs hydrosol and MFLs for contrasting at both T2 and T1 relaxation were determined. On T2 weighted images, the MFLs effectively increased the contrast if compared with MNPs hydrosol, while on T1 weighted images, MNPs hydrosol contrasting was more efficient than that of MFLs. In vivo magnetic resonance imaging (MRI) contrasting properties of MFLs and their effects on tumor and normal tissues morphology, were investigated in rats with transplanted renal cell carcinoma upon intratumoral administration of MFLs. No significant morphological changes in rat internal organs upon intratumoral injection of MFLs were detected, suggesting that the liposomes are relatively safe and can be used as the potential contrasting agents for MRI.

Electrospinning of functional materials for biomedicine and tissue engineering

Published data on nanostructured materials prepared by electrospinning are analyzed and generalized. Particular attention is devoted to the design and properties of nanocomposite fibrous materials and methods for modification and functionalization of fibre surface. The prospects for the application of non-woven materials for biotissue engineering and for the development of smart materials are considered. The bibliography includes 330 references.

Synthesis of magnetite hydrosols in inert atmosphere

A setup is described for magnetite hydrosol synthesis in inert atmosphere via coprecipitation of bi- and trivalent iron salts in the presence of a base with the formation of nanoparticles having desired sizes and chemical composition. The size of nanoparticles is estimated based on analysis of light-scattering and transmission-electron-microscopy data. The chemical composition of magnetite nanoparticles is monitored by Raman spectroscopy.

Optical heating and temperature determination of core-shell gold nanoparticles and single-walled carbon nanotube microparticles.

The real-time temperature measurement of nanostructured materials is particularly attractive in view of increasing needs of local temperature probing with high sensitivity and resolution in nanoelectronics, integrated photonics, and biomedicine. Light-induced heating and Raman scattering of single-walled carbon nanotubes with adsorbed gold nanoparticles decorating silica microparticles are reported, by both green and near IR lasers. The plasmonic shell is used as nanoheater, while the single-walled carbon nanotubes are Raman active and serve as a thermometer. Stokes and Anti-Stokes Raman spectra of single-walled carbon nanotubes serve to estimate the effective light-induced temperature rise on the metal nanoparticles. The temperature rise is constant with time, indicating stability of the adsorption density. The effective temperatures derived from Stokes and Anti-Stokes intensities are correlated with those measured in a heating stage. The resolution of the thermal experiments in our study was found to be 5-40 K.

Composite SERS-based satellites navigated by optical tweezers for single cell analysis

Herein, we have designed composite SERS-active micro-satellites, which exhibit a dual role: (i) effective probes for determining cellular composition and (ii) optically movable and easily detectable markers. The satellites were synthesized by the layer-by-layer assisted decoration of silica microparticles with metal (gold or silver) nanoparticles and astralen in order to ensure satellite SERS-based microenvironment probing and satellite recognition, respectively. A combination of optical tweezers and Raman spectroscopy can be used to navigate the satellites to a certain cellular compartment and probe the intracellular composition following cellular uptake. In the future, this developed approach may serve as a tool for single cell analysis with nanometer precision due to the multilayer surface design, focusing on both extracellular and intracellular studies.

Synthesis of magnetite hydrosols and assessment of their impact on living systems at the cellular and tissue levels using MRI and morphological investigation

MRI and morphological investigations into internal organ tissues and tumors in rats with liver cancer PC-1 under the intraperitoneal administration of magnetite hydrosols have been performed. The absence of any toxic effect of magnetite nanoparticles at low concentrations (0.325 mg/mL) has been determined using neutrophil granulocytes. A technique for the synthesis of citrate-stabilized magnetite hydrosols by the coprecipitation of Fe2+ and Fe3+ salts is described. Their electrokinetic potential is −32 ± 2 mV at pH 6.5 ± 0.1. The size distribution of magnetite nanoparticles is obtained by dynamic light scattering. The average size of magnetite nanoparticles is 23 ± 6 nm. The absorption spectra of magnetite hydrosols have been measured. The dependence of the optical density on the concentration has also been obtained. Molar absorption coefficients of magnetite nanoparticles have been calculated at the following wavelengths: 532, 633, 660, and 785 nm.

Composite magnetic microcapsules based on multilayer assembly of ethanol-soluble polyimide brushes and magnetite nanoparticles: preparation and response to magnetic field gradient

Microcapsules consisting of a calcium carbonate core template surrounded by shells containing magnetite nanoparticles and ethanol-soluble polyimide brushes with polymethacrylic acid side chains were assembled using a layer-by-layer technique under nonaqueous conditions. These microcapsules represent a potential solution to the challenging problem of encapsulating water-soluble compounds, particularly low molecular weight drugs. It was possible to move these microcapsules with magnetite nanoparticles in their shells by applying a magnetic field gradient. The novel microcapsules were characterized by optical microscopy, atomic force microscopy, and scanning electron microscopy. Using the brush-like polyanions instead of linear polyanions made it possible to increase the shell thickness gain per ionic assembly cycle by a factor of ~3.

Influence of Heat Treatment on Loading of Polymeric Multilayer Microcapsules with Rhodamine B

Layer-by-layer assembled polymeric multilayer capsules (PMC) of micrometer sizes are permeable for molecules below 1 KDa; therefore, the efficacy of such capsules in the delivery of low molecular weight water soluble bioactive compounds and drugs is frequently challenged. Thermally induced contraction of hollow PMC is explored here to enhance their loading efficacy with model compound, fluorescent rhodamine B (RhB). Four bilayered capsules obtained of poly(diallyldimethylammonium chloride)/polystyrene sulfonate ([PDADMAC/PSS]4 ) or poly-l-arginine/dextran sulfate ([PARG/DS]4 ) on sacrificial CaCO3 spherical microparticles are postloaded with RhB at ambient or elevated temperatures. The influence of heat on capsule loading is determined quantitatively by varying the amounts of capsules in the batch and keeping the concentration of RhB constant. The applied heat improves the loading efficacy of [PDADMAC/PSS]4 capsules at concentrations up to 2.25 × 109 capsules mL-1 , but has a reversed effect on [PARG/DS]4 capsules at all studied concentrations ((0-3.5) × 109 capsules mL-1 ).

An investigation of the morphology of Langmuir films based on molecular polyimide brushes containing magnetite nanoparticles

Molecular brushes having a polyimide (PI) backbone with degree of polycondensation n = 33 and polymethylmethacrylate (PMMA) side chains with two different degrees of polymerization (m = 63 and m = 114) were synthesized by the method of controlled atom transfer radical polymerization. Hydrophobic magnetite nanoparticles of a size of 18 ± 2 nm were prepared. Langmuir monolayers on the basis of the polyimide brushes and composite monolayers, containing magnetite nanoparticles with a hydrophobic surface, were formed at the water/air interface. It is found that, in the condensed state of the monolayer at the surface pressure values from 25 to 40 mN/m, the limiting surface area A0 per side chain of a brush grows with an increase in the length of PMMA side chains of polymer brushes almost by a factor of 2: from A0 = 744 ± 64 Å2 for PI-graft-PMMA-63 to A0 = 1644 ± 50 Å2 for PI-graft-PMMA-114. Increasing the magnetite solution aliquot mixed with the polymer brush solution at the ratios from 1 : 2 and 1 : 1 to 2 : 1 leads to a rise in the limiting surface area values A0 to 1072 ± 59 Å2 for the first two ratios to 2534 ± 79 Å2 for the third one. The obtained monolayers were transferred onto mica by the Langmuir-Schaeffer method at different surface pressure values (0.5, 10, and 25 mN/m). With the use of the method of atomic force microscopy, it is shown that a four- to sixfold increase in the mean roughness of a composite film surface due to the inclusion of magnetite nanoparticles into the polymer brush monolayer is typical of all samples.

Functionalization of direct emulsion disperse phase surface by zinc oxide nanoparticles using layer-by layer electrostatic assembly

Polyelectrolyte and nanocomposite (zinc oxide nanoparticles/polymer) coatings on the surface of a direct-emulsion disperse phase containing fluorescent dye were obtained using layer-by-layer electrostatic assembly. The volume fraction of inorganic nanoparticles was varied by changing the number of polymer layers in the coating. The loaded microcontainers were characterized by fluorescence confocal and scanning electron microscopy (SEM). The parameters influencing the quality characteristics of the images were found, and the optimal conditions for the preparation and study of such systems using SEM were selected. It was demonstrated that the ultrasonic treatment of microcontainers influences the degree of their aggregation and, in the case of nanocomposite coatings, results in a reduction of the microparticle size.