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Biomedical subjects

Dmitry G Shchukin

Publications and source records attributed to Dmitry G Shchukin.

14 recordsLinked to original sources
PubMed2006

Ultrasonically induced opening of polyelectrolyte microcontainers.

The effect of ultrasonic treatments of different intensity and duration on the integrity and permeability of polyelectrolyte capsules was investigated both in poly(allylamine)/poly(styrene sulfonate) and Fe(3)O(4)/poly(allylamine)/poly(styrene sulfonate) polyelectrolyte capsules. Ultrasonic treatment of polyelectrolyte capsules induces the destruction of the polyelectrolyte shell and the release of the encapsulated material even at short (5 s) sonification times. The presence of magnetite nanoparticles significantly improves the efficiency of the ultrasonically stimulated release of the encapsulated compounds and enables magnetically controlled delivery to the desired site before ultrasonic treatment. Release of the encapsulated compound induced at ultrasonic power comparable to those of ultrasonic generators applied in medicine, demonstrating practical application of the ultrasonically triggered capsule opening in medicine.

Allylamine↗
PubMed2006

Sonochemical nanosynthesis at the engineered interface of a cavitation microbubble.

This work demonstrates the potential of sonochemistry to become a most valuable tool for nanotechnology if the underlying complex processes are understood and controlled. It is shown that control of cavitation requires controlling of interfaces at the microsec time scale and thus a diversity of phenomena are observed using different surfactants. By means of concrete examples it is shown that non-equilibrium nanostructures, e.g. Ru/Pt core-shell nanoparticles can be prepared. Hollow microbubbles with nanoparticles in the wall, which may contain gases over weeks, can be constructed by sonication of the corresponding colloid solutions.

Microbubbles↗
PubMed2006

Microcontainers with electrochemically reversible permeability.

The present study demonstrates a novel application of polyelectrolyte microcapsules as microcontainers with electrochemically reversible flux of redox active materials into and out of the capsule volume. Incorporation of the capsules inside the conducting polymer (polypyrrole) film results in a new composite electrode combining electrocatalytic and conducting properties of the polypyrrole with the storage and release properties of the capsules. This electrode, if loaded with electrochemical fuels, can possess electrochemically controlled switching between "open/closed" states of the capsule shell and be of practical interest for a new type of chemically rechargeable batteries or fuel cells. A special explanation for the potential depending loading and unloading of the capsule inner volume may be related to the fact that the polyelectrolyte capsules experience a potential gradient in the polypyrrole matrix within which the polyions of the shell can be moved.

Journal Article↗
PubMed2005

Thermal behavior of polyelectrolyte multilayer microcapsules. 1. The effect of odd and even layer number.

The temperature-dependent behavior of hollow polyelectrolyte multilayer capsules consisting of poly(diallyldimethylammonium chloride) (PDADMAC) and poly(styrene sulfonate) (PSS) with a different number of layers was investigated in aqueous media using confocal laser scanning microscopy, scanning and transmission electron microscopy, atomic force microscopy, and elemental analysis. Capsules with an even number of layers exhibited a pronounced shrinking at elevated temperature resulting in a transition to a dense sphere, whereas capsules with an odd number of layers swelled during heating to 5-fold of their initial size followed by their rupture. This effect increases for odd layer numbers and decreases for even layer numbers with increasing layer number. According to elemental analysis, an excess of PDADMAC monomers exists within the multilayers of capsules with an odd number of layers leading to a repulsion between the positive charges, whereas shells with an even number of layers have a balanced ratio between the oppositely charged polyions, so that the temperature-dependent behavior is controlled by the different interactions between polyelectrolytes and the bulk water. At a certain temperature, the polyelectrolyte material softens thus facilitating any rearrangement. Besides incubation temperature, the duration of heating has an influence on the restructuring of the multilayers.

Electrolytes↗
PubMed2005

Urea photosynthesis inside polyelectrolyte capsules: effect of confined media.

The influence of the restricted volume of poly(styrene sulfonate)/poly(allylamine hydrochloride) capsules of different size (2.2, 4.2, and 8.1 microm) on the TiO2-assisted photosynthesis of urea from inorganic precursors (CO2 and NO(3-)) in aqueous solution was demonstrated. Poly(vinyl alcohol) was employed as electron donor to facilitate the photosynthetic process. Decreasing the size of the confined microvolume of polyelectrolyte capsules accelerates the NO(3-) photoreduction, which is a limiting stage of the urea photosynthesis and, correspondingly, increases the efficiency of urea production. The highest yield of urea photosynthesis (37%) was achieved for Cu-modified TiO2 nanoparticles encapsulated inside 2.2 microm poly(styrene sulfonate)/poly(allylamine hydrochloride) capsules.

Journal Article↗
PubMed2004

Remote activation of capsules containing Ag nanoparticles and IR dye by laser light.

We present a novel method for remote release of an encapsulated material from polyelectrolyte capsules based on laser light illumination. Two different components were introduced in the polyelectrolyte shells of PAH/PSS capsules-either Ag nanoparticles or IR dye-to induce absorption of light. Under laser illumination the capsules containing Ag nanoparticles or IR dye were deformed or cut, thus providing a venue for remote release of encapsulated materials. The experiments were conducted with a low-power near-infrared continuous-wave laser diode.

Journal Article↗
PubMed2004

Nanoassembly of biodegradable microcapsules for DNA encasing.

A new microcontainer for DNA delivery based on biocompatible poly[beta-glucuronic acid-(1 --> 3)-N-acetyl-beta-galactosamine-6-sulfate-(1 --> 4)](chondroitin sulfate)/poly(-l-arginine) microcapsules with 40 nm thick molecularly organized shell was proposed. DNA molecules were deposited as DNA/sperimidine complex on the surface of template 4 mum core particles followed by layer-by-layer nanoassembly of protective chondroitin sulfate/poly(-l-arginine) shell. After template core dissolution, DNA molecules were captured inside microcapsules retaining a natural double-helix structure. The developed DNA encapsulation approach can be employed for targeted delivery of plasmid DNA in living cells.

Biocompatible Materials↗
PubMed2003

Photocatalytic microreactors based on TiO2-modified polyelectrolyte multilayer capsules.

Spatially confined photocatalytic microreactors for microheterogeneous photoreduction of metal ions from aqueous solutions have been developed. The microreactors consist of hollow micron-sized polyelectrolyte capsules with photoactive TiO2 nanoparticles incorporated in the walls. Additional improvements in metal photoreduction efficiency were achieved by filling the microcapsule cavity with a more effective electron donor.

Journal Article↗
PubMed2002

Magnetic photocatalysts of the core-shell type.

Two magnetic core-shell type photocatalytic systems are presented: first, Zn0.35Ni0.65Fe2,O4-SiO2-TiO2, showed high activity in the photooxidation of oxalate, and the other, Fe3O4-Fe2O3-polyaniline: P2W18O62(6-), was tested in the reaction of SO2 photooxidation.

Journal Article↗