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

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

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

Complexes of Sodium Pectate with Nickel for Hydrogen Oxidation and Oxygen Reduction in Proton-Exchange Membrane Fuel Cells

A number of nickel complexes of sodium pectate with varied Ni2+ content have been synthesized and characterized. The presence of the proton conductivity, the possibility of the formation of a dense spatial network of transition metals in these coordination biopolymers, and the immobilization of transition ions in the catalytic sites of this class of compounds make them promising for proton-exchange membrane fuel cells. It has been established that the catalytic system composed of a coordination biopolymer with 20% substitution of sodium ions for divalent nickel ions, Ni (20%)-NaPG, is the leading catalyst in the series of 5, 15, 20, 25, 35% substituted pectates. Among the possible reasons for the improvement in performance the larger specific surface area of this sample compared to the other studied materials and the narrowest distribution of the vertical size of metal arrays were registered. The highest activity during CV and proximity to four-electron transfer during the catalytic cycle have also been observed for this compound

Nanoscale isoindigo-carriers: self-assembly and tunable properties

Over the last decade isoindigo derivatives have attracted much attention due to their high potential in pharmacy and in the chemistry of materials. In addition, isoindigo derivatives can be modified to form supramolecular structures with tunable morphologies for the use in drug delivery. Amphiphilic long-chain dialkylated isoindigos have the ability to form stable solid nanoparticles via a simple nanoprecipitation technique. Their self-assembly was investigated using tensiometry, dynamic light scattering, spectrophotometry, and fluorometry. The critical association concentrations and aggregate sizes were measured. The hydrophilic–lipophilic balance of alkylated isoindigo derivatives strongly influences aggregate morphology. In the case of short-chain dialkylated isoindigo derivatives, supramolecular polymers of 200 to 700 nm were formed. For long-chain dialkylated isoindigo derivatives, micellar aggregates of 100 to 200 nm were observed. Using micellar surfactant water-soluble forms of monosubstituted 1-hexadecylisoindigo as well as 1,1′-dimethylisoindigo were prepared for the first time. The formation of mixed micellar structures of different types in micellar anionic surfactant solutions (sodium dodecyl sulfate) was determined. These findings are of practical importance and are of potential interest for the design of drug delivery systems and new nanomaterials

Thymine-Modified Nanocarrier for Doxorubicin Delivery in Glioblastoma Cells

Brain tumor glioblastoma is one of the worst types of cancer. The blood–brain barrier prevents drugs from reaching brain cells and shields glioblastoma from treatment. The creation of nanocarriers to improve drug delivery and internalization effectiveness may be the solution to this issue. In this paper, we report on a new nanocarrier that was developed to deliver the anticancer drug doxorubicin to glioblastoma cells. The nanocarrier was obtained by nanoemulsion polymerization of diallyl disulfide with 1-allylthymine. Diallyl disulfide is a redox-sensitive molecule involved in redox cell activities, and thymine is a uracil derivative and one of the well-known bioactive compounds that can enhance the pharmacological activity of doxorubicin. Doxorubicin was successfully introduced into the nanocarrier with a load capacity of about 4.6%. Biological studies showed that the doxorubicin nanocarrier composition is far more cytotoxic to glioblastoma cells (T98G) than it is to cancer cells (M-HeLa) and healthy cells (Chang liver). The nanocarrier improves the penetration of doxorubicin into T98G cells and accelerates the cells’ demise, as is evident from flow cytometry and fluorescence microscopy data. The obtained nanocarrier, in our opinion, is a promising candidate for further research in glioblastoma therapy

Langmuir Monolayers and Thin Films of Amphifilic Thiacalix[4]arenes. Properties and Matrix for the Immobilization of Cytochrome <i>c</i>

Formation and properties of Langmuir films of thiacalix[4]­arene (TCA) derivatives containing N-donor groups on the lower rim (YO­(CH₂)₃CN; OCH₂CN; NH₂; OCH₂ArCN-<i>p</i>) in <i>1</i>,<i>3</i>-<i>alternate</i> conformation on aqueous subphase and solid substrates have been studied. Only <i>tetra</i>-cyanopropoxy-<i>p</i>-<i>tert</i>-butylthiacalix­[4]­arene <b>1</b> forms a typical monomolecular layer with perpendicular orientation of the macrocycle relative to the water–air interface that is able to immobilize cytochrome <i>c</i> in the entire range of the surface pressure. Obtained monolayers were transferred by Langmuir–Schaefer technique onto quartz, indium–tin oxide (ITO), and silicon. It was demonstrated that protein activity is retained after immobilization on the substrate