T. V. Bukreeva

Controlled enzyme-catalyzed degradation of polymeric capsules templated on CaCO₃: Influence of the number of LbL layers, conditions of degradation, and disassembly of multicompartments

Enzyme-catalyzed degradation of CaCO₃-templated capsules is presented. We investigate a) biodegradable, b) mixed biodegradable/synthetic, and c) multicompartment polyelectrolyte multilayer capsules with different numbers of polymer layers. Using confocal laser scanning microscopy we observed the kinetics of the non-specific protease Pronase-induced degradation of capsules is slowed down on the order of hours by either increasing the number of layers in the wall of biodegradable capsules, or by inserting synthetic polyelectrolyte multilayers into the shell comprised of biodegradable polymers. The degradation rate increases with the concentration of Pronase. Controlled detachment of subcompartments of multicompartment capsules, with potential for intracellular delivery or in-vivo applications, is also shown.

Ultrasonically Assisted Polysaccharide Microcontainers for Delivery of Lipophilic Antitumor Drugs: Preparation and in Vitro Evaluation

High toxicity, poor selectivity, and severe side effects are major drawbacks of anticancer drugs. Various drug delivery systems could be proposed to overcome these limitations. The aim of this study was to fabricate polysaccharide microcontainers (MCs) loaded with thymoquinone (TQ) by a one-step ultrasonication technique and to study their cellular uptake and cytotoxicity in vitro. Two MC fractions with a mean size of 500 nm (MC-0.5) and 2 μM (MC-2) were prepared and characterized. Uptake of the MCs by mouse melanoma M-3 cells was evaluated in both 2D (monolayer culture) and 3D (multicellular tumor spheroids) models by confocal microscopy, flow cytometry, and fluorimetry. The higher cytotoxicity of the TQ-MC-0.5 sample than the TQ-MC-2 fraction was in good correlation with higher MC-0.5 accumulation in the cells. The MC-0.5 beads were more promising than the MC-2 particles because of a higher cellular uptake in both 2D and 3D models, an enhanced antitumor effect, and a lower nonspecific toxicity.

A new approach to modification of polyelectrolyte capsule shells by magnetite nanoparticles

A new method for modifying polyelectrolyte capsule shells by magnetic nanoparticles is proposed: the in situ synthesis of magnetite by chemical condensation. The capsule cores were spherical calcium carbonate microparticles, while polymer shells were prepared using the layer-by-layer electrostatic adsorption of polyallylamine and polystyrene sulfonate. After in situ synthesis, nanoparticles of different shapes are formed on the capsule shell; the main crystalline phase of nanoparticles is magnetite. The thus obtained nanocomposite capsules are highly sensitive to external magnetic fields.

Size control and structure features of spherical calcium carbonate particles

The size of porous spherical calcium carbonate particles obtained by precipitation from a supersaturated solution has been controlled using bovine serum albumin as an organic additive and ethylene glycol and glycerol as cosolvents of the reaction mixture. The structural aspects of the formation of these particles, which affect the possibility of controlling their sizes, are considered. Highly porous vaterite particles with an average size of about 500 nm have been obtained by adding ethylene glycol and glycerol to the reaction mixture and agitation for no less than 30 min. It is shown that particles are formed as a result of the attachment of vaterite nanocrystallites, the shape of which is anisotropic and can be described by a biaxial ellipsoid.

Permeability adjustment of polyelectrolyte micro-and nanocapsules by laser irradiation

Laser radiation was used for permeability increase up to destroy of polyelectrolyte capsules. Silver and gold nanoparticles was synthesized and incorporated into capsule shells to attain the sensitivity of microcapsules to laser radiation. Lasers of different power and wavelength were used. The sensitivity of nanocomposite shell to laser radiation can be controlled by nanoparticle shape, content and distribution into the shell.

Heat-driven size reduction of biodegradable polyelectrolyte multilayer hollow capsules assembled on CaCO3 template

Aiming to explore elevated temperatures as a tool for miniaturization of biodegradable polymer multilayer capsules, assembled on spherical vaterite micron- and submicron-sized particles, we subject the shells composed of dextran sulfate (DS) and poly-L-arginine (Parg) to a heat treatment. Changes of the capsule size are studied at various temperatures and ionic strengths of the continuous phase. Unlike some synthetic polymer multilayer shells (their response to heat treatment depends on the number of layers and their arrangement), the biodegradable Parg/DS capsules exhibit size reduction and profound compaction regardless of their initial size, number of polymer layers and polymer layer sequence. The capsule response to heat is stable at ionic strengths of the continuous phase not exceeding 0.1 M NaCl.

Incorporation of Naphthalocyanine into Shells of Polyelectrolyte Capsules and Their Disruption under Laser Radiation

Different methods have been proposed for the incorporation of a dye, vanadyl tetra-5,14,23,32-phenyl-2,3-naphthalocyanine, into the shells of polyelectrolyte capsules. Capsule preparation conditions have been selected to provide efficient incorporation of the dye and stability of capsules to aggregation. A suspension of the capsules has been irradiated with lasers operating at wavelengths belonging to the near-infrared spectral region. It has been found that the capsules can be disrupted under the irradiation. Continuous and pulsed laser radiations have been shown to have different effects on the capsules.

A study of the interaction between polyelectrolyte-coated nanostructured CaCO 3 particles and a stearic acid monolayer spread at the water/air interface

The influence of nanostructured CaCO3 particles, both uncoated and coated with a polyelectrolyte (poly(diallyldimethylammonium chloride), polyethyleneimine, fluorescein-5-isothiocyanate-labeled poly(allylamine hydrochloride), or sodium polystyrene sulfonate), on a stearic acid monolayer spread on the surface of an aqueous subphase has been studied. The interaction of the particles present in the subphase with the monolayer as depending on the presence and composition of a polymer coating has been estimated with the help of compression isotherms and the Brewster angle microscopy. The monolayers were transferred from the aqueous subphase onto a solid substrate and studied by scanning electron microscopy. Strong interaction has been revealed between the calcium carbonate particles and the stearic acid monolayer. It has been shown that the transfer of the monolayer from the aqueous suspension surface onto the solid substrate may be accompanied by the detachment of the polymer coating from the surface of CaCO3 particles or their transfer together with the monolayer.

Possibilities of surface-sensitive X-ray methods for studying the molecular mechanisms of interaction of nanoparticles with model membranes

The processes of structural rearrangement in a model membrane, i.e., an arachic acid monolayer formed on a colloidal solution of cerium dioxide or magnetite, are studied in situ in real time by the methods of X-ray standing waves and 2D diffraction. It is shown that the character of the interaction of nanoparticles with the monolayer is determined by their nature and sizes and depends on the conditions of nanoparticle synthesis. In particular, the structure formation in the monolayer–particle system is greatly affected by the stabilizer (citric acid), which is introduced into the colloidal solution during synthesis.

Nanostructured Calcium Carbonate Particles As Fluorophore Carriers

The immobilization of dyes (rhodamine 6G, photosens, and photoditazine) into porous spherical calcium carbonate microparticles (vaterite modification) has been performed, and the desorption of dyes in water and sodium chloride solution of physiological concentration has been investigated. Dyes were immobilized in two ways: (i) by the adsorption of fluorophore onto previously prepared calcium carbonate particles and (ii) by adding a material to the reaction mixture when forming particles. It is found that the highest degree of particle loading (12.4 wt %) is obtained when using the second way for photoditazine. Desorption of dyes occurs mainly because of the recrystallization of particles; however, the carrier can retain photodynamic preparations for a long time.