Triclosan-loaded with high encapsulation efficiency into PLA nanoparticles coated with β-cyclodextrin polymer

The purpose was to prepare triclosan-loaded polylactic acid nanoparticles containing β-cyclodextrin polymer shell, evaluate triclosan release from the particles using Franz diffusion cells and to study the stability of the particles in presence of a model protein, bovine serum albumin. The nanoparticles were prepared by a solvent displacement process. The nanoparticles were characterized by their size, encapsulation efficiency and morphology. They were of spherical shape with hydrodynamic diameter of about 100 or 200 nm depending on the polylactic acid used. Their high encapsulation efficiency (~90%) indicated that triclosan is easily incorporated into the nanoparticles. The nanoparticles displayed slow and sustained triclosan release patterns (diffusion coefficient about 10^?22 m²/s) and the β-cyclodextrin polymer coating was stable under simulated physiological conditions. All these data indicated that these novel core–shell nanoparticles might provide a promising carrier system for controlled release of triclosan and other hydrophobic drugs after systemic administration.     

Self-association of α-tocopherol: a computer simulation

Self-association of α-tocopherol molecules in the gas phase was simulated using quantum chemical calculations in the B3LYP/6-31G(d,p)/6-31G(d) approximation. The influence of electric field on the energy characteristics of oligomerization of α-tocopherol was also considered.     

Synthesis of novel bioconjugates of α-tocopherol with lupane triterpenoids

Russian Chemical Bulletin - The first representatives of gA-tocopherol bioconjugates with lupane triterpenoids were synthesized using amino acid residues and dipeptides as linkers between the...     

Determination of α-tocopherol in Cosmetic Products by Chronopotentiometry

Abstract

In the present study, a rapid chronopotentiometric method was developed for the determination of α-tocopherol in various cosmetic products. Determination of α-tocopherol is based on its irreverse oxidation by constant current at the planar glassy carbon electrode. The influence of the most important experimental parameters of chronopotentiometry was investigated. After optimization, an appropriate procedure for the sample preparation was developed. Under the defined experimental conditions, a detection limit of 7.5 mg L^?1 of α-tocopherol was obtained. The accuracy of the defined method was confirmed by means of recovery assay. The developed method was successfully applied to quantitation of α-tocopherol in various cosmetic products.     

Synthesis of triterpene acids conjugates with α-tocopherol synthetic analogs

Heterodimers were synthesized of pharmacologically important α-tocopherol synthetic analogs with triterpene acids(betulonic, betulinic), potential polyfunctionsl drugs possessing antioxidant activity. The combination of the fragments of biologically active substances was performed through linkers (residues of succinic acid, hydrazine, glycine, tetramethylenediamine) binding the side chain of the antioxidant molecule with atoms C³ or C²⁸ of the terpenoid.     

Synthesis of α-tocopherol analogs with unsaturated side chain and their transformation into the corresponding chromans with ω-functionalized side chain

-Tocopherol analogs with double bond-containing side chains were synthesized by condensation of trimethylhydroquinone with optically active (3R/S,4S)-3,4,8-trimethylnona-1,7-dien-3-ol and linalool in the presence of the zeolite-containing Tseokar-10 aluminosilicate. Ozonolysis of these compounds gave the corresponding chromans with -formyl or (after hydride reduction) -hydroxyl groups in the side chain.     

Selective determination of o-phenylenediamine by surface-enhanced Raman spectroscopy using silver nanoparticles decorated with α-cyclodextrin

Microchimica Acta - We have developed a SERS method for the determination of o-phenylenediamine (OPD) in water. It is based on the chemical cyclization reaction of OPD with nitrite in acidic...     

Hybrid supramolecular hydrogels induced by Au nanoparticles protected with MPEG-b-PCL copolymers with α-cyclodextrin

To fabricate supramolecular hydrogel hybridised with well-dispersed gold nanoparticles (AuNPs), water-soluble AuNPs protected with methoxy poly(ethylene glycol)-b-poly(?-caprolactone) (MPEG-b-PCL) self-assembled monolayers (MPEG-b-PCL/AuNPs) were synthesised and used as guest molecules to interact with α-cyclodextrin (α-CD) in aqueous solutions. Transmission electron microscopy measurement results showed that the diameter of the AuNPs produced was about 6–10 nm with a narrow particle size distribution, and stained MPEG-b-PCL/AuNPs micelles made in water clearly displayed the formation of a core-shell structure with a single gold core per micelle. X-ray diffraction measurement results confirmed that there existed the characteristic peaks of both AuNPs and polypseudorotaxanes formed via the inclusion complexation of MPEG-b-PCL moieties with α-CD in as-obtained hydrogels. UV–visible spectra displayed that the same surface plasma resonance absorption peaks appeared at 526 nm for both aqueous dispersion of MPEG-b-PCL/AuNPs and resultant hybrid hydrogel with α-CD. Rheological measurements showed that the hybrid hydrogel has a lower mechanical strength and viscosity, and a relatively prolonged gelation time in comparison with the corresponding native hydrogel. The mechanical strength of the hydrogel nanocomposites could be tailored by modulating the concentration of MPEG-b-PCL/AuNPs and α-CD as well as the composition of MPEG-b-PCL/AuNPs.     

Solubility enhancement of triflumizole by host-guest interaction with β-cyclodextrin

Summary The solubility enhancement of triflumizole, a systemic fungicide, by -cyclodextrin inclusion complexation was investigated by electron absorption spectroscopy. The respective association constant determined by different methods was estimated to 470±20M ^–1 in aqueous solution. A model for the host-guest complexation was deduced by molecular calculations.

---

Löslichkeitsverbesserung von Triflumizole durchHost-Guest-Complexierung mit -Cyclodextrin

Zusammenfassung Die Löslichkeitsverbesserung des systemischen Fungizids Triflumizole durch Komplexierung mit -Cyclodextrin wurde mittels Elektronenabsorptionsspektroskopie untersucht. Die entsprechende Stabilitätskonstante wurde durch verschiedene Methoden erfaßt und betrug im wäßrigen Medium 470±20M ^–1. Ein Model für denHost-Guest-Complex wurde durch Molekülrechnungen erstellt.

     

Metal–organic framework ZIF-8 loaded with rhodium nanoparticles as a catalyst for hydroformylation

Porous metal–organic framework ZIF-8 materials containing incorporated rhodium (Rh@ZIF-8) and rhodium chloride (RhCl₃@ZIF-8) nanoparticles were obtained and tested as a catalytic reaction vessel in the reactions of hydroformylation of 1-decene and styrene. Catalytic tests with Rh@ZIF-8 showed that the selectivity and conversion of the hydroformylation reaction depended on the size of the substrate molecule. The incorporation of catalytic nanoparticles into the pores of a metal–organic framework opens up new possibilities for regioselective hydroformylation.     

Voltammetric determination of tumor necrosis factor-α based on the use of an aptamer and magnetic nanoparticles loaded with gold nanoparticles

Microchimica Acta - The authors are presenting an electrochemical aptasensor for tumor necrosis factor-alpha (TNF-α) detection that is aided by the use of magnetic nanoparticles (NPs) and two...     

The reactivity enhancement in Diels–Alder cycloaddition of 1,3-diene by cation encapsulation to C60: a computational insight

The origin of the experimentally known preference for [6,6] bonds in cycloaddition reactions involving C₆₀ has been computationally explored. To this end, we examined the reactions of 1,3-dienes with fullerene (C₆₀) in the context of an approach to open a large orifice on the fullerene framework by using the activation model of reactivity in combination with the energy analysis method. In this study, the effect of the alkali metal of Li⁺, Na⁺, and K⁺ as an encapsulated element was investigated on the kinetic and thermodynamic behaviors of the Diels–Alder (DA) process. Our calculations indicated that encapsulated Na⁺ and K⁺ cations are located close to the center of the C₆₀ molecule; however, encapsulated Li⁺ is displaced from the center, which leads to a higher reactivity for Li⁺@C₆₀ in DA cycloaddition reaction in the gas phase. Also, benzene as a non-polar solvent affects the DA reactions greater than water as a polar solvent. Different analyses show that solvent changes the catalysis reaction performance, in which a greater efficiency was obtained for K⁺ in the solvent in comparison with other alkali ions because of a facilitated mechanism of electron transfer.

     

Corrosion protection enhancement effect by mixed silica nanoparticles of different sizes incorporated in a sol–gel silica film

We demonstrate an enhancement of corrosion protection by sol–gel silica film including mixed silica nanoparticles of 10 and 50 nm. Low-temperature silica films were prepared by sol–gel dip-coating method, followed by a thermal annealing at 200 °C. Importantly, film with mixed particles exhibits lower corrosion current density and slower loss of film resistance during the immersion in electrolyte solution, showing an improved corrosion protection over the film with 50 nm particles. The improved corrosion protectability of the mixed particles comes from the suppressed diffusion of ionic species by a close packing of 10 nm particles.     

Reduction of α,β-unsaturated nitroolefins into nitroalkanes with Hantzsch ester promoted by isothiouronium salts

α,β-Unsaturated nitroolefins were reduced into nitroalkanes with a Hantzsch ester, promoted by S-benzyl isothiouronium iodide. The reactions proceeded successfully to afford the desired products in high yields and with excellent chemoselectivity.     

Preparation and characterization of zein/chitosan complex for encapsulation of α-tocopherol, and its in vitro controlled release study

Chitosan (CS) nanoparticles coated with zein has been newly demonstrated as a promising encapsulation and delivery system for hydrophilic nutrient with enhanced bioactivities in our previous study. In this study, a hydrophobic nutrient, α-tocopherol (TOC), was successfully encapsulated into zein/CS complex. The fabrication parameters, including zein concentration, zein/CS weight ratio, and TOC loading percentage, were systematically investigated. The physicochemical and structural analysis showed that the electrostatic interactions and hydrogen bonds were major forces responsible for complex formation. The scanning electron microscopy study revealed the spherical nature with smooth surface of complex. TOC encapsulation was also evidenced by differential scanning calorimetry. The particle size and zeta potential of the complex varied from 200 to 800 nm and +22.8 to +40.9 mV, respectively. The kinetic release profile of the TOC showed burst effect followed by slow release. Compared with zein nanoparticles, zein/CS complex provided better protection of TOC release against gastrointestinal conditions, due to CS coatings. Zein/CS complex is believed to be a promising delivery system for supplementation or treatment of hydrophobic nutrients or drugs.     

Capillary electrophoretic study of thiolated α-cyclodextrin-capped gold nanoparticles with tetraalkylammonium ions

Capillary zone electrophoresis (CZE) has been employed to characterize nanometer-sized thiolated α-cyclodextrin-capped gold nanoparticles (α-CD-S-AuNPs). The addition of tetrabutylammonium (Bu₄N⁺) ions to the run buffer greatly narrows the migration peak of α-CD-S-AuNP. The optimal run buffer was determined to be 10 mM Bu₄N⁺ in 30 mM phosphate buffer at pH 12 and an applied voltage of 15 kV. The effect of various tetraalkylammonium ions on the peak width and electrophoretic mobility (μ_e) of α-CD-S-AuNP was studied in detail. Bu₄N⁺ ions assist in inter-linking the α-CD-S-AuNPs and narrowing the migration peak in CZE. This observation can be explained by the fact that each Bu₄N⁺ ion can simultaneously interact with several hydrophobic cavities of the surface-attached α-CDs on AuNPs. The TEM images show that α-CD-S-AuNPs with Bu₄N⁺ are linked together but in the absence of Bu₄N⁺, they are more dispersed. The migration mechanism in CZE is based on the formation of inclusion complexes between Bu₄N⁺ and α-CD-S-AuNPs which induces changes in the charge-to-size ratio of α-CD-S-AuNPs and μ_e. An inverse linear relationship (r² > 0.998) exists between the μ_e and size of α-CD-S-AuNPs in the core range 1.4–4.1 nm. The CZE analyses are rapid with migration time less than 4 min. A few nanoliters of each of the α-CD-S-AuNP samples were injected hydrodynamically at 0.5 psi for 5 s. Our work confirms that CZE is an efficient tool for characterizing the sizes of α-CD-S-AuNPs using Bu₄N⁺ ions.     

Reduction of irradiation off-odor and lipid oxidation in ground beef by α-tocopherol addition and the use of a charcoal pack

A combination of a charcoal pack during irradiation and α-tocopherol addition into ground beef was applied to eliminate an irradiation characteristic off-odor and to retard the lipid oxidation caused by the irradiation process. Ground beef was mixed with 200 ppm α-tocopherol and gamma irradiated with 0, 5, and 10 kGy with or without a charcoal pack present during the irradiation treatment. The pH of the control group was lower than that of α-tocopherol and charcoal pack treatment initially but increased rapidly and showed higher pH at day 7. Addition of α-tocopherol with or without charcoal pack addition showed lower 2-thiobarbituric acid reactive substances values in irradiated ground beef at days 3 and 7 compared to those without addition. The color of ground beef was not significantly affected by the treatment. However, odor preference result showed that 10 kGy-irradiated ground beef with a combination of charcoal pack and α-tocopherol addition had higher scores than the control group regardless of irradiation. Solid-phase microextraction (SPME) gas chromatograph/mass spectrometry (GC/MS) analysis identified various volatile compounds that were created by irradiation of ground beef. These compounds were reduced or eliminated when a charcoal pack was used during the irradiation process. The results of the present study imply that combination of packaging with a charcoal pack during the irradiation process and addition of α-tocopherol into ground beef is a good method to effectively eliminate an irradiation off-odor and retard the lipid oxidation development in ground beef caused by irradiation.     

Scaffold membranes for selective adsorption of α-tocopherol by phase inversion covalently imprinting technique

A molecular-imprinted membranes targeted to α-tocopherol (α-Toc) were prepared by phase inversion of polymer containing covalently bound template group to the polymer through ester group. For preparation of such polymer, a template-containing monomer, α-tocopherol methacrylate (α-TMA) was synthesized and copolymerized with acrylonitrile (AN). Phase inversion of the AN copolymer was carried out from the DMSO solution in water non-solvent. After membrane formed, removal of the template was performed in treatment with HCl acid solution. It was observed that the amounts of α-Toc bound to imprinted and non-imprinted membranes in ethanol/water (1:1%, v/v) were 20.8 ± 0.4 and 2.2 ± 0.1 μmol/g, respectively. Scatchard analysis indicated that the imprinted membranes exhibited high affinity and good selective binding of α-Toc relative to its analogs, δ-Toc, and 4-chromanol (4-Chr). Evidences showed that separation was achieved with separation factor of 15.5 for α-Toc/4-Chr in ethanol/water 1:1% (v/v) solution by simple filtration procedure with high flux permeation.