Elena Shchukina

LbL coated microcapsules for delivering lipid-based drugs☆

Nowadays, more than 40% of new pharmacologically active compounds exhibit poor water solubility, which requires the development of the new methods for their administration and delivery. One of the most promising approaches for the development of such delivery systems is the use of layer-by-layer assembly technology for encapsulation of the lipid-based drugs. This technique permits the step-wise adsorption of various components as the layer growth is governed by their electrostatic attraction and allows the formation of multilayer shells with nanometer-scale precision. The proposed review surveys the application of layer-by-layer assembly for emulsions, nanoparticles, and capsule-based delivery systems for lipid-based drugs.

Heterocyclic analogs of prostaglandines: IV. Synthesis of 3,7-interphenylene 3,10(11)-dioxa-13-azaprostanoids and 9-oxa-7-azaprostanoids based on tetronic acid and aromatic aldehydes

An approach was developed to the synthesis of stable in metabolism 3,7-interphenylene 3,10-dioxa-13-aza-and 3,11-dioxa-13-azaprostanoids, and also 9-oxa-7-azaprostanoids with interphenylene and terminal phenyl fragments in the ω-chain based on 3-(alkoxybenzylidene)-and 3-(3-phenylallylidene)tetrahydrofuran-2,4-diones obtained by Knoevenagel condensation of tetronic acid with alkoxy-substituted aromatic aldehydes and cinnamic aldehyde.

Nanocapsules containing salt hydrate phase change materials for thermal energy storage

Thermal energy storage has many important applications and is most efficiently achieved by latent heat storage using phase change materials (PCMs). Salt hydrates have advantages such as high energy storage density, high latent heat and incombustibility. However, they suffer from drawbacks such as incongruent melting and corrosion of metallic container materials. By encapsulating them in a polymer shell, problems can be eliminated. Here we demonstrate a simple method to nanoencapsulate magnesium nitrate hexahydrate, employing in situ miniemulsion polymerisation with ethyl-2-cyanoacrylate as the monomer. Using sonication to prepare miniemulsions improved the synthesis by reducing the amount of surfactant required as the stabiliser. The thermal properties were analysed by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Fourier transform infrared spectroscopy (FTIR) was employed to prove the presence of salt hydrate within the nanocapsules. The results show that the capsules are 100–200 nm in size, have salt hydrate located in the core and are stable over at least 100 thermal cycles with only a 3% reduction in latent heat. Supercooling is also drastically reduced. To the best of our knowledge, this is the first time that an encapsulated salt hydrate PCM has been proven to have a lifetime of 100+ heat uptake/release cycles.

Capsules with external navigation and triggered release.

Encapsulation is an important technology for pharmaceutical industry, food production, et cetera. Its current level of development requires capsule functionalization. One of the interesting ideas to provide new functionality to the microcapsule and nanocapsule is layer-by-layer deposition of functional species. This technique provides step-by-step adsorption of various species (polyelectrolytes, nanoparticles, proteins) when the layer growth is controlled by electrostatic, hydrogen bonding, hydrophobic forces and forming multilayer shells with nanometer precision. This review article introduces recent achievements of layer-by-layer technique attaining external navigation ability and release properties the capsule shell.

Gas-phase synthesis of terbium and lutetium carboxylates

Gas-phase ligand exchange between volatile lanthanide dipivaloylmethanates (Ln(dpm)3; Hdpm is dipivaloylmethane, Ln = Tb, Lu) and o-substituted aromatic carboxylic acids (HCarb = Hsal is o-hydroxybenzoic acid, Habz is o-aminobenzoic acid, Hpobz is o-phenoxybenzoic acid, Hpa is o-anilinobenzoic acid). The gas-phase reaction involves the formation of the mixed-ligand complex Ln (dpm)3−n(Carb)n, which is subsequently converted into tris-carboxylate (Ln(Carb)3) on heating of the product in vacuum.

Heterocyclic analogs of prostaglandins: III*. Synthesis of 10-oxa-13-aza, 11-oxa-13-aza, and 9-oxa-7-aza prostanoids from 3-acyl- and 3-(3-arylprop-2-enoyl)furan-2,4-diones

A number of new 10-oxa-13-aza, 11-oxa-13-aza, and 9-oxa-7-aza prostanoids belonging to the B series were synthesized on the basis of 3-acyl-and 3-(3-arylprop-2-enoyl)furan-2,4(3H,5H)-diones. The scheme of synthesis includes selective hydrogenation of the exocyclic carbonyl group and reduction of the conjugated double bond in the acyl fragment of 3-acyl-and 3-(3-arylprop-2-enoyl)furan-2,4(3H,5H)-diones to obtain 3-alkyl-and 3-(3-arylpropyl)furan-2,4(3H,5H)-diones, transformation of the latter into the corresponding regioisomeric enol ethers via regioselective O-alkylation, and treatment of the enol ethers with primary aliphatic amines.

Heterocyclic analogs of prostaglandins: II. Synthesis of 10-oxaprostanoids with isoxazole and isoxazoline fragments in α-and ω-chain

By the use of “nitrile oxide procedure” from 3-alkyl(arylalkyl)-substituted 2,5-dihydro-2-furanones new 10-oxaprostanoids were prepared containing an isoxazole (isoxazoline) fragment in the α-or ω-prostanoid chain.

Nanoencapsulated crystallohydrate mixtures for advanced thermal energy storage

Controlled storage of thermal energy, especially in the ‘low temperature’ region 100 cycles as monitored by differential scanning calorimetry), due to the functional properties of the capsule shell and spatial confinement preventing water loss and incongruent melting during phase transitions. Mixtures of encapsulated crystallohydrates have differing energy uptake/release depending on their inherent design. Additive mixtures (mixtures of energy capsules containing single crystallohydrates) possess separate heat uptake/release transitions at temperatures corresponding to each crystallohydrate type. Latent heat of each transition is proportional to the content of the corresponding energy capsules in the mixture. Nanocapsules containing mixed crystallohydrate core have synergetic effects from Mg(NO3)2·6H2O and Na2SO4·10H2O components at their eutectic point: low-temperature phase transition and high latent heat capacity. Chemical composition, integrity and morphology of the capsules were analysed by scanning electron microscopy, Fourier transform infrared spectroscopy and thermogravimetric analysis.

Binding Mechanism of the Model Charged Dye Carboxyfluorescein to Hyaluronan/Polylysine Multilayers

Biopolymer-based multilayers become more and more attractive due to the vast span of biological application they can be used for, e.g., implant coatings, cell culture supports, scaffolds. Multilayers have demonstrated superior capability to store enormous amounts of small charged molecules, such as drugs, and release them in a controlled manner; however, the binding mechanism for drug loading into the multilayers is still poorly understood. Here we focus on this mechanism using model hyaluronan/polylysine (HA/PLL) multilayers and a model charged dye, carboxyfluorescein (CF). We found that CF reaches a concentration of 13 mM in the multilayers that by far exceeds its solubility in water. The high loading is not related to the aggregation of CF in the multilayers. In the multilayers, CF molecules bind to free amino groups of PLL; however, intermolecular CF–CF interactions also play a role and (i) endow the binding with a cooperative nature and (ii) result in polyadsorption of CF molecules, as proven by fitting of the adsorption isotherm using the BET model. Analysis of CF mobility in the multilayers by fluorescence recovery after photobleaching has revealed that CF diffusion in the multilayers is likely a result of both jumping of CF molecules from one amino group to another and movement, together with a PLL chain being bound to it. We believe that this study may help in the design of tailor-made multilayers that act as advanced drug delivery platforms for a variety of bioapplications where high loading and controlled release are strongly desired.

CHAPTER 8:Application of Clay Materials as Nanocontainers for Self-Healing Coatings

This chapter surveys the application of clay materials (in particular halloysites) in self-healing coatings. The release mechanisms of the encapsulated inhibitors are discussed and different shell/stopper compositions are demonstrated for smart response to the local environmental changes in the corroded/damaged area. In general, clay minerals have a loading capacity lower than common polymer capsules, and they do not have large versatility in controlling the release of corrosion inhibitors. However, they are mechanically and thermally robust, cheap and available in thousands of tons.