Polyelectrolyte nanocontainers: controlled binding and release of indomethacin

Herein, polyelectrolyte capsules containing anti-inflammatory drug indomethacin were formed using layer-by-layer strategy, which involves alternative deposition of oppositely charged polyelectrolytes, such as poly(acrylic acid) and poly(ethyleneimine) (or chitosan) onto the drug substrate. Two variants of encapsulation have been implemented: direct deposition of polyelectrolytes onto indomethacin dispersed in water at рН 6, and preliminary formation of soft matrix by solubilization of indomethacin in micellar solutions of cationic surfactants. The inclusion of indomethacin into nanosized polyelectrolyte capsules (hydrodynamic diameter of three- and five-layer capsules is 90–180 nm) has given a new form of indomethacin with the drug content of 0.20–0.25%, which exceeds its limiting solubility in water nearly by the factor of 40. The choice of materials and procedures used for preparation of capsules, as well as the number of polyelectrolyte layers that form shell has provided the control of the drug release from capsule and resulted in the design of pharmaceutical dosage forms with long-lasting effect

Synthesis of spherical iron-oxide nanoparticles of various sizes under different synthetic conditions

The present work describes eleven different syntheses of oleate-coated iron-oxide nanoparticles via thermolysis of Fe(III) oleate in high-boiling point organic solvents using a heating mantle with manual heating rate control. It has been shown that heating of iron oleate for 10 min in octadecane at 318 degrees C (average heating rate is about 7.7 degrees C/min) does not lead to the formation of iron-oxide nanoparticles, whereas decrease of the heating rate and further more continuous reflux (20, 30, 60 min) trigger their formation. The experimental results show that the use of heating mantle without automatic heating controller makes it harder to precisely control the size of the nanoparticles and indicate that certain variations of the heating rates may result in iron-oxide nanoparticles of slightly different sizes. It has been also exemplified that prehistory of the iron oleate namely its storage time may affect the morphology of the resulting iron-oxide nanoparticles.Web of Science73112722271

Platinum Nanoscale Lattice on a Graphite Surface Using Cetyltrimethylammonium Bromide Hemi- and Precylindrical Micelle Templates

One-dimentional (1-D) thin-layer (2–5 nm) parallel strips of Pt on a graphite surface have been synthesized via a template-directed chemical deposition of Pt. The templates are a surface micellar strip of cetyltrimethylammonium bromide (CTAB) at highly ordered pyrolytic graphite (HOPG). The concentration- and temperature-dependent morphology of surface micellar strips of CTAB at the graphite/aqueous solution is elucidated by using the atomic force microscopy (AFM) soft-contacting techniques. The dimentions and repeat period of the Pt strips can be widely controlled by the temperature: the width is from 47 to 169 nm and the period from 134 to 233 nm in the temperature range 25–33 °C. The morphological characteristics of the Pt strips depend on those of the original surface micellar strips. The fact that the strips are composed of metallic platinum was confirmed by testing the membrane electrode assembly with the strips in a special fuel cell. This approach could be extended to fabricate a wide range of 1-D self-assembling metallic nanostructures on surfaces using micelle-like self-assemblies carrying metal ions at interfaces

Adsorption and Premicellar Aggregation of CTAB Molecules and Fabrication of Nanosized Platinum Lattice on the Glass Surface

Premicellar aggregation processes were investigated in a wide range of concentrations and temperatures of cetyltrimethylammonium bromide (CTAB) aqueous solutions. Two independent techniques were involved to study adsorption and aggregation of CTAB molecules at the glass/solution interface. Electronic spin resonance (ESR) was used to estimate microviscosity properties through the reorientation correlation time τ_<i>c</i> of (2,2,6,6-tetramethylpiperidin-1-oxyl), while atomic force microscopy (AFM) was involved to evaluate the CTAB molecule morphology at the glass/solution interface. In the dependence of τ_<i>c</i> vs the CTAB concentration three discontinuities were revealed within 0.2–0.5, 0.5–1.02, and 1.02–1.1 mM narrow concentration ranges, which are probably connected with the formation of bilayer and hemispherical, hemicylindrical, cylindrical, and spherical admicelles. The images of some of them at the glass surface have been independently obtained by AFM. One-dimensional thin layer (2 nm) of Pt parallel strips on a glass surface have been synthesized by chemical vapor deposition of the Pt on the surface micellar CTAB linear templates followed by washing of the latter

Synthetic Tuning of CoII-Doped Silica Nanoarchitecture Towards Electrochemical Sensing Ability

The present work introduces both synthesis of silica nanoparticles doped with CoII ions by means of differently modified microemulsion water-in-oil (w/o) and St&ouml;ber techniques and characterization of the hybrid nanoparticles (CoII@SiO2) by TEM, DLS, XRD, ICP-EOS, SAXS, UV-Vis, and UV-Vis/DR spectroscopy and electrochemical methods. The results reveal the lack of nanocrystalline dopants inside the hybrid nanoparticles, as well as no ligands, when CoII ions are added to the synthetic mixtures as CoII(bpy)3 complexes, thus pointing to coordination of CoII ions with Si-O- groups as main driving force of the doping. The UV-Vis/DR spectra of CoII@SiO2 in the range of d-d transitions indicate that St&ouml;ber synthesis in greater extent than the w/o one stabilizes tetrahedral CoII ions versus the octahedral ions. Both cobalt content and homogeneity of the CoII distribution within CoII@SiO2 are greatly influenced by the synthetic technique. The electrochemical behavior of CoII@SiO2 is manifested by one oxidation and two reduction steps, which provide the basis for electrochemical response on glyphosate and HP(O)(OEt)2 with the LOD = 0.1 &mu;M and the linearity within 0.1&ndash;80 &mu;M. The St&ouml;ber CoII@SiO2 are able to discriminate glyphosate from HP(O)(OEt)2, while the w/o nanoparticles are more efficient but nonselective sensors on the toxicants

Closed polymer containers based on phenylboronic esters of resorcinarenes

Novel polymer nanospheres (p(SRA-B)) were prepared by cross-linking a sulfonated resorcinarene (SRA) with phenylboronic acid. p(SRA-B) shows good stability in water and can be used as a nanocontainer for the pH- and glucose-controlled substrate release. Fluorescent dyes (fluorescein, pyrene and 1,3,6,8-pyrenetetrasulfonic acid tetrasodium salt) were successfully loaded into p(SRA-B). The release of dye is achieved by lowering the pH value to 3 or by adding glucose

Fluorescent magnetic nanoparticles for modulating the level of intracellular Ca2+ in motoneurons

This report introduces both synthesis and in vitro biological behaviour of dual magnetic-fluorescent silica nanoparticles. The amino group-decoration of 78 nm sized silica nanoparticles enables their efficient internalization into motoneurons, which is visualized by the red fluorescence arising from [Ru(dipy)(3)](2+) complexes encapsulated into a silica matrix. The internalized nanoparticles are predominantly located in the cell cytoplasm as revealed by confocal microscopy imaging. The magnetic function of the nanoparticles resulted from the incorporation of 17 nm sized superparamagnetic iron oxide cores into the silica matrix, enabling their responsivity to magnetic fields. Fluorescence analysis revealed the "on-off" switching of Ca2+ influx under the application and further removal of the permanent magnetic field. This result for the first time highlights the movement of the nanoparticles within the cell cytoplasm in the permanent magnetic field as a promising tool to enhance the neuronal activity of motoneurons.Web of Science1134161131610