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Encapsulation
Kinds of Encapsulation Terms modified by Encapsulation Selected AbstractsBulky Pyrazolate-Based Compartmental Ligand Scaffolds: Encapsulation of an Edge-Sharing Cu6O2 Bitetrahedral Core,EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 34 2008Anna Sachse Abstract Upon reaction with Cu(OAc)2·H2O, pyrazole-based ligands with two appended imine chelate arms in the 3- and 5-positions of the pyrazole and bulky substituents at the imine-N yield Cu6 complexes [L2Cu6(,-OAc)6(,4 -O)2] (1a,b). They feature an unusual {Cu6(,4 -O)2}-bitetrahedral core, only the second example of this structural motif. ESI mass spectrometric and UV/Vis data confirm that the Cu6 complexes stay intact in solution, and magnetic and high-field EPR measurements reveal an S = 0 ground state with the first excited triplet at ,E , 95 cm,1. Although the new hexanuclear systems are too complex for deriving all individual exchange constants from powder susceptibility data, a rough idea of the complete energy level spectrum could be obtained.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source] Solid-State Anion,Guest Encapsulation by Metallosupramolecular Capsules Made from Two Tetranuclear Copper(II) ComplexesEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 29 2007Emilio Pardo Abstract A new cationic tetranuclear copper(II) complex self-assembles from one 1,3-phenylenebis(oxamato) (mpba) bridging ligand and four CuII ions partially blocked with N,N,N,,N, -tetramethylethylenediamine (tmen) terminal ligands. In the solid state, two of these tetracopper(II) oxamato complexes of bowl-like shape and helical conformation then serve as a building block for the generation of either hetero- (MP) or homochiral (MM/PP) dimeric capsules depending on the nature of the encapsulated anion guest, perchlorate or hexafluorophosphate. The overall magnetic behaviour of these metallosupramolecular capsules does not depend on the nature of the encapsulated anion guest, but it is consistent with the dimer-of-dimer structure of the tetracopper(II) cation host, where the interdimer magnetic coupling through the meta -phenylenediamidate bridge is negligibly smallrelative to the reasonably strong intradimer one across the oxamato bridge.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source] Sol-Gel Entrapped Pyridinium Hydrobromide Perbromide as a Recyclable Bromination Agent: Its Application to a One-Pot Bromination and Dehydrobromination ProcessEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 6 2006Yevgenia Levin Abstract Silica sol-gel encaged pyridinium hydrobromide perbromide can be used for clean, odorless bromination of a variety of substrates, including alkenes, ketones, and arenes. The used heterogenized bromination reagent can be recharged with bromine and recycled. In the presence of sol-gel entrapped 1,5,7-triazabicyclo[4.4.0]dec-5-ene, dibromides are dehydrobrominated to give vinyl monobromides and/or alkynes. Encapsulation of the pyridinium derivative and the guanidine base within separate sol-gel matrices enables the use of both opposing reagents in one-pot reactions without their mutual destroying each other. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source] Therapy with Cell Encapsulation for Substitution of Organ Function and Tumor Treatment (Adv. Eng.ADVANCED ENGINEERING MATERIALS, Issue 8 2009Mater. The cover shows life and dead assay demonstrating living cells within a cellulose sulfate capsule. More information can be found in the article by J. M. Lohr et al. on page B129. [source] Encapsulation and Stabilization of Reactive Aromatic Diazonium Ions and the Tropylium Ion Within a Supramolecular HostEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 24 2004Julia L. Brumaghim Abstract Supramolecular assemblies with internal cavities are being developed as nanoscale reaction vessels to protect or modify the reactivity of guest species through encapsulation. Diazonium cations and the tropylium cation were examined for their ability to encapsulate in the tetrahedral [Ga4L6]12, supramolecular assembly. The 4-(diethylamino)benzenediazonium cation 1 readily formed a 1:1 host,guest complex with this assembly, and this encapsulation prevented 1 from reacting with 2,4-pentanedione in D2O. The tropylium cation also formed a 1:1 host,guest complex with the [Ga4L6]12, assembly, greatly slowing its decomposition in D2O. Encapsulation in the protected environment of this host cavity alters the reactivity of these guest molecules, giving them greater stability. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004) [source] Hydrophobic Chemistry in Aqueous Solution: Stabilization and Stereoselective Encapsulation of Phosphonium Guests in a Supramolecular HostEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 22 2004Julia L. Brumaghim Abstract Encapsulation of guest molecules inside supramolecular host assemblies provides a way to stabilize reactive species in aqueous solution. The stabilization of reactive phosphonium/ketone adducts of the general formula [R1MeC(OH)PR3]+ by encapsulation as guest molecules within a [Ga4L6]12, tetrahedral metal,ligand assembly is reported; although these cations decompose in aqueous solution, encapsulation inside the hydrophobic cavity of the assembly lengthens their lifetimes considerably, in some cases up to weeks. By varying the phosphane (PMe3, PEt3, PPhMe2, and PPh2Me) and ketone (acetone, methyl ethyl ketone, 1,1,1-trifluoroacetone, and fluoroacetone) which form these adducts, as well as the pD of the solutions, it was determined that the pH of the solution as well as the size and shape of the guest cations play an important role in the stability of these host,guest complexes. Encapsulation of chiral guests in the chiral [Ga4L6]12, assembly results in the formation of diastereomers, as characterized by 1H, 19F, and 31P NMR spectroscopy. Although the [Ga4L6]12, assembly is formed from non-chiral ligands, the assembly itself has ,,,, or ,,,, chirality around the metal centers. Due to the chirality of this assembly, diastereomeric selectivity is observed upon initial guest encapsulation (typical diastereomeric excesses are 30,50%). This initial diastereomeric selectivity decreases over time to reach an equilibrium but does not become 1:1, indicating both kinetic and thermodynamic processes promote selective guest encapsulation. These experiments demonstrate further the applications of nanoscale reaction vessels, self-assembled by design from non-chiral ligands, in providing a chiral and hydrophobic environment for guest molecules in aqueous solution. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004) [source] Therapy with Cell Encapsulation for Substitution of Organ Function and Tumor Treatment,ADVANCED ENGINEERING MATERIALS, Issue 8 2009J. Matthias Löhr Cell encapsulation represents an innovative technique. However, clinical applications are sparse. Most experiments and clinical studies have been performed with either alginate or cellulose sulfate capsules, containing several cell lines and a broad variety of applications, ranging all the way from substitution for impaired organ function and release of cytokines or growth factors to gene-directed enzyme prodrug therapy. A few clinical studies have been conducted and/or are under way. [source] Hot-Pressed Glass Matrix Composites Containing Pyrochlore Phase Particles for Nuclear Waste Encapsulation,ADVANCED ENGINEERING MATERIALS, Issue 7 2003A.R. Boccaccini As alternative immobilization materials for Pu-bearing nuclear waste, lead-containing glass matrix composites with homogeneously distributed lanthanum zirconate pyrochlore particles (up to 30,% by volume) have been developed. Fabrication by hot pressing at the relatively mild temperature of 610,°C leaves the pyrochlore structure of the La zirconate unchanged, which is crucial for the containment of radioactive nuclei. The Figure, an SEM image of a polished sample with 30,% La2Zr2O7, demonstrates the homogeneous particle distribution and absence of pores. [source] Encapsulation and release of a fluorescent probe, khusimyl dansylate, obtained from vetiver oil by complex coacervationFLAVOUR AND FRAGRANCE JOURNAL, Issue 1 2008A. S. Prata Abstract The essential oil of vetiver [Vetiveria zizanoides (L.) Nash ex. Small] is widely used in the perfume industry, owing to its pleasant, long-lasting, woody aroma. If this substance can be encapsulated in microparticles so that its release can be controlled, the effective duration of its properties should be extended for a much longer period of time. The present study was thus designed to investigate the encapsulation of this vetiver essential oil in microparticles. Since the detection of the effective release of such a complex mixture from these microparticles into the receiving medium can be problematic, an identifiable probe can be released with it to facilitate evaluation of the progression of the release process. Zizanoic acid is one of the compounds found in vetiver oil which depreciates its sensorial quality. This acid was thus extracted and reduced to the corresponding alcohol, khusimol, which was combined with dansyl chloride to form a fluorescent ester, khusimyl dansylate (KD). The vetiver oil and the fluorescent probe were then encapsulated (100:1) in microparticles produced by the complex coacervation of gum Arabic and gelatin. The microparticles showed spherical shape, multinuclear distribution of the core material and high encapsulation efficiency (95%). Two versions of these microparticles, moist and freeze-dried ones, were tested for the release of the KD into an ethanol medium. The moist particles released the whole KD after 5 h, although only 80% of the fluorescent probe was released with the freeze-dried microparticles at that time, probably due to the constriction caused by freeze-drying. The release of the components of vetiver oil, under the same experimental conditions, was followed, in parallel, by gas chromatography and the results obtained were compared and discussed. Copyright © 2007 John Wiley & Sons, Ltd. [source] Surface Patterning: Spatiotemporal Control over Molecular Delivery and Cellular Encapsulation from Electropolymerized Micro- and Nanopatterned Surfaces(Adv.ADVANCED FUNCTIONAL MATERIALS, Issue 18 2009Funct. This frontispiece image shows a multicomponent chip inspired by a vaccine node for specific T-cell stimulation, as described by Stern et al. on page 2888. The chip is functionalized with two different polymers (silver and black) as shown in the clockwise fabrication steps in the corners, each of which presents and releases different molecules necessary for stimulation. T-cells are stained red and dendritic cells are stained green. The inset image shows the reverse polymer pattern. [source] Spatiotemporal Control over Molecular Delivery and Cellular Encapsulation from Electropolymerized Micro- and Nanopatterned Surfaces,ADVANCED FUNCTIONAL MATERIALS, Issue 18 2009Eric Stern Abstract Bioactive, patterned micro- and nanoscale surfaces that can be spatially engineered for three-dimensional ligand presentation and sustained release of signaling molecules represent a critical advance for the development of next-generation diagnostic and therapeutic devices. Lithography is ideally suited to patterning such surfaces due to its precise, easily scalable, high-throughput nature; however, to date polymers patterned by these techniques have not demonstrated the capacity for sustained release of bioactive agents. Here a class of lithographically defined, electropolymerized polymers with monodisperse micro- and nanopatterned features capable of sustained release of bioactive drugs and proteins is demonstrated. It is shown that precise control can be achieved over the loading capacity and release rates of encapsulated agents and this aspect is illustrated using a fabricated surface releasing a model antigen (ovalbumin) and a cytokine (interleukin-2) for induction of a specific immune response. Furthermore, the ability of this technique to enable three-dimensional control over cellular encapsulation is demonstrated. The efficacy of the described approach is buttressed by its simplicity, versatility, and reproducibility, rendering it ideally suited for biomaterials engineering. [source] Porous Chromium Terephthalate MIL-101 with Coordinatively Unsaturated Sites: Surface Functionalization, Encapsulation, Sorption and CatalysisADVANCED FUNCTIONAL MATERIALS, Issue 10 2009Do-Young Hong Recent ideas concerning site-selective functionalization of chromium terephtha-late MIL-101 are discussed, focusing on the utilization of unsaturated Cr(III) sites (see image). Recent advances in synthesis, selective surface functionalization, outstanding sorption properties, encapsulation of nanoobjects, and catalytic applications in MIL-101 are also discussed. [source] Encapsulation and Ostwald Ripening of Au and Au,Cl Complex Nanostructures in Silica Shells,ADVANCED FUNCTIONAL MATERIALS, Issue 13 2006W. Lou Abstract We report a general template strategy for rational fabrication of a new class of nanostructured materials consisting of multicore shell particles. Our approach is demonstrated by encapsulating Au or Pt nanoparticles in silica shells. Other superstructures of these hollow shells, like dimers, trimers, and tetramers can also be formed by nanoparticle-mediated self-assembly. We have also used the as-prepared multicore Au,silica hollow particles to perform the first studies of Ostwald ripening in confined microspace, in which chloride was found to be an efficient mediating ligand. After treatment with aqua regia, Au,Cl complex is formed inside the shell, and is found to be very active under in,situ transmission electron microscopy observations while confined in a microcell. This aspect of the work is expected to motivate further in,situ studies of confined crystal growth. [source] Cover Picture: Biomineralized Polysaccharide Capsules for Encapsulation, Organization, and Delivery of Human Cell Types and Growth Factors (Adv. Funct.ADVANCED FUNCTIONAL MATERIALS, Issue 6 2005Mater. Abstract The cover shows biomineralized polysaccharide capsules with specifiable make-up, which can provide microenvironments for stabilization, growth, and differentiation of human cell types, as reported by Oreffo and co-workers on p.,917. The capsules are amenable to complexation with a range of bioactive molecules and cells, offering tremendous potential as multifunctional scaffolds and delivery vehicles in tissue regeneration of hard and soft tissues. The construction of biomimetic microenvironments with specific chemical and physical cues for the organization and modulation of a variety of cell populations is of key importance in tissue engineering. We show that a range of human cell types, including promyoblasts, chondrocytes, adipocytes, adenovirally transduced osteoprogenitors, immunoselected mesenchymal stem cells, and the osteogenic factor, rhBMP-2 (BMP: bone morphogenic protein), can be successfully encapsulated within mineralized polysaccharide capsules without loss of function in vivo. By controlling the extent of mineralization within the alginate/chitosan shell membrane, degradation of the shell wall and release of cells or rhBMP-2 into the surrounding medium can be regulated. In addition, we describe for the first time the ability to generate bead-in-bead capsules consisting of spatially separated cell populations and temporally separated biomolecule release, entrapped within alginate/chitosan shells of variable thickness, mineralization, and stability. Such materials offer significant potential as multifunctional scaffolds and delivery vehicles in tissue regeneration of hard and soft tissues. [source] Biomineralized Polysaccharide Capsules for Encapsulation, Organization, and Delivery of Human Cell Types and Growth Factors,ADVANCED FUNCTIONAL MATERIALS, Issue 6 2005W. Green Abstract The construction of biomimetic microenvironments with specific chemical and physical cues for the organization and modulation of a variety of cell populations is of key importance in tissue engineering. We show that a range of human cell types, including promyoblasts, chondrocytes, adipocytes, adenovirally transduced osteoprogenitors, immunoselected mesenchymal stem cells, and the osteogenic factor, rhBMP-2 (BMP: bone morphogenic protein), can be successfully encapsulated within mineralized polysaccharide capsules without loss of function in vivo. By controlling the extent of mineralization within the alginate/chitosan shell membrane, degradation of the shell wall and release of cells or rhBMP-2 into the surrounding medium can be regulated. In addition, we describe for the first time the ability to generate bead-in-bead capsules consisting of spatially separated cell populations and temporally separated biomolecule release, entrapped within alginate/chitosan shells of variable thickness, mineralization, and stability. Such materials offer significant potential as multifunctional scaffolds and delivery vehicles in tissue regeneration of hard and soft tissues. [source] Encapsulation of Water-Insoluble Drugs in Polymer Capsules Prepared Using Mesoporous Silica Templates for Intracellular Drug DeliveryADVANCED MATERIALS, Issue 38 2010Yajun Wang Water-insoluble compounds were encapsulated in polymer capsules through mesoporous silica nanoparticle-mediated layer-by-layer assembly. The drug-loaded capsules exhibit excellent colloidal stability and high potency to colorectal cancer cells in vitro with similar cytotoxicity to the free drug dissolved in organic solvent. [source] Al2O3/ZrO2 Nanolaminates as Ultrahigh Gas-Diffusion Barriers,A Strategy for Reliable Encapsulation of Organic ElectronicsADVANCED MATERIALS, Issue 18 2009Jens Meyer Highly efficient gas-diffusion barriers based on nanolaminates of alternating Al2O3 and ZrO2 layers grown at 80,°C by atomic-layer deposition are presented. Ultralow water-vapor permeation rates are reported, and a dramatic reduction of statistical defects on larger areas was found compared to single Al2O3 layers. This study provides a concept for the encapsulation of organic optoelectronic devices. [source] One-Pot Synthesis of Catalytically Stable and Active Nanoreactors: Encapsulation of Size-Controlled Nanoparticles within a Hierarchically Macroporous Core@Ordered Mesoporous Shell SystemADVANCED MATERIALS, Issue 13 2009Xiao-Yu Yang Size-controlled, catalytically active nanoparticles are successfully encapsulated in a one-pot synthesis to form novel hierarchical macroporous core@mesoporous shell structures, where macroporous cores are connected by uniform and ordered mesoporous channels. Most importantly, the encapsulated nanoparticles can be used as "nanoreactors", with high activities and excellent long-term recycling stability. [source] Flavour encapsulation and controlled release , a reviewINTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 1 2006Atmane Madene Summary Flavours can be among the most valuable ingredients in any food formula. Even small amounts of some aroma substance can be expensive, and because they are usually delicate and volatile, preserving them is often a top concern of food manufacturers. Encapsulation describes different processes to cover an active compound with a protective wall material and it can be employed to treat flavours so as to impart some degree of protection against evaporation, reaction, or migration in a food. Encapsulation of flavours has been attempted and commercialized using many different methods such as spray drying, spray chilling or spray cooling, extrusion, freeze drying, coacervation and molecular inclusion. The choice of appropriate microencapsulation technique depends upon the end use of the product and the processing conditions involved in the manufacturing product. This overview describes each method cited above in terms of the basic chemical and/or physical principles involved and covers mechanisms of flavour release from food matrices. [source] The use of spray drying to microencapsulate 2-acetyl-1-pyrroline, a major flavour component of aromatic riceINTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 2 2003Muanmai Apintanapong Summary Different ratios of gum acacia and maltodextrins were used to investigate the appropriate wall materials for encapsulation, by spray drying, of 2-acetyl-1-pyrroline (ACPY). This compound, which is the major flavour component of aromatic rice, was extracted from pandan (Pandanus amaryllifolius) leaves by steam distillation. The amounts of ACPY before and after spray drying encapsulation were not significantly different (P < 0.05). Better retention of ACPY was obtained by encapsulation. In its liquid form ACPY degraded quickly as 63% reduction occurred in a basic solution after 7 days; however, only 30% reduction was found in acidic solution after 35 days of storage. After 72 days of storage, the amount of ACPY in encapsulated powders made with differing amounts of gum acacia and maltodextrin decayed as follows: ratios of gum acacia:maltodextrin of 70:30, 60:40, 50:50, 40:60, 30:70 and 0:100 gave the following amounts of degradation of 27.7, 33.4, 43.2, 35.7, 30.6 and 32.6% respectively. Encapsulation in 70:30 gum acacia:maltodextrin gave the best retention of ACPY. [source] In vitro evaluation of the activity of microencapsulated carvacrol against Escherichia coli with K88 piliJOURNAL OF APPLIED MICROBIOLOGY, Issue 6 2009Q. Wang Abstract Aims:, The aim of the current study is to develop encapsulation of essential oils for oral delivery to the small intestine of pigs in order to retain their antimicrobial activity. Methods and Results:, Carvacrol was used as a model essential oil and successfully encapsulated in microcapsules made from Ca-alginate hydrogel using an emulsion,extrusion technology with high encapsulation efficiency. This encapsulation method did not compromise the antimicrobial activity when tested against Escherichia coli K88 in a culture medium, as well as in a simulated gastrointestinal model. In the simulated gastrointestinal model, <20% of encapsulated carvacrol was released in the simulated gastric fluid; the rest was nearly completely released in the intestinal fluid after 6 h of incubation. Conclusions:, Encapsulation in Ca-alginate microcapsules could effectively reduce the early absorption of carvacrol in the upper gastrointestinal tract after oral administration, therefore, retains its potential antibacterial activity for the small intestine. Significance and Impact of the Study:, The developed encapsulation method is expected to be suitable for encapsulation of other essential oils. The results from this study would increase the likelihood of success in the application of essential oils as antimicrobial agents for controlling enteric diseases in pigs. [source] A structure/function study of polyaminoamide dendrimers as silica scale growth inhibitorsJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 6 2005Konstantinos D Demadis Abstract Dendrimers have attracted immense attention during the last decade due to their interesting properties both from a basic and an applied research viewpoint. Encapsulation of metal nanoparticles for catalysis, drug delivery and light harvesting are only some applications of dendrimers that are breaking new ground. A novel application of dendrimer technology is described in the present paper that relates to industrial water treatment. Industrial water systems often suffer from undesirable inorganic deposits. These can form either in the bulk or on metallic surfaces, such as heat exchangers or pipelines. Silica (SiO2) scale formation and deposition is a major problem in high-silica-containing cooling waters. Scale prevention rather than removal is highly desired. In this paper, benchtop screening tests on various silica inhibition chemistries are reported, with emphasis on materials with a dendrimeric structure. Specifically, the inhibition properties of commercially available STARBURST® polyaminoamide (PAMAM) dendrimers generations 0.5, 1, 1.5, 2, and 2.5 are investigated in detail together with other commonly-used scale inhibitors. Experimental results show that inhibition efficiency largely depends on structural features of PAMAM dendrimers such as generation number and nature of the end groups. PAMAM dendrimers are effective inhibitors of silica scale growth at 40 ppm dosage levels. PAMAM dendrimers also act as silica nucleators, forming SiO2,PAMAM composites. This occurs because the SiO2 formed by incomplete inhibition interacts with cationic PAMAM-1 and -2. The general scope of silica formation and inhibition in industrial waters is also discussed. Copyright © 2005 Society of Chemical Industry [source] Optimizing the Use of Garlic Oil as Antimicrobial Agent on Fresh-Cut Tomato through a Controlled Release SystemJOURNAL OF FOOD SCIENCE, Issue 7 2010J. Fernando Ayala-Zavala Abstract:, Encapsulation of garlic oil (GO) in ,-cyclodextrin (,-CD) was undertaken to generate a release system of antimicrobial volatiles and tested on microbial growth and sensory quality of fresh-cut tomato. GO volatile profile was characterized by gas chromatography mass spectrometry and to demonstrate the disadvantages of applying free GO to fresh-cut tomato, the effect of different free oil treatments (0, 50, 100, and 200 ,g/100 g) on microbial growth and sensorial quality was tested. The effect of GO capsules (0, 0.25, 0.5, and 1 g/100 g) on microbial growth and sensory quality of tomato was also investigated. Allyl disulfide was the most abundant GO compound identified. The release of volatiles from GO: ,-CD capsules (12: 88 [w/w] ratio) was evaluated at 100% relative humidity (RH). Close to 70% of GO volatiles were released from capsules when exposed to 100% RH during 5 wk. The most effective antimicrobial concentrations of free oil (100 and 200 ,g/100 g) applied to tomatoes did not present acceptable sensory quality for panelists. Tomato was affected by the highest concentration of GO capsules applied, showing the lowest microbial growth and the highest sensory quality. In this context, successful encapsulation in ,-CD could stimulate further interest in the use of GO for the control of microbial growth in fresh-cut tomato. Practical Application:, The present study demonstrated that relative humidity in-package of fresh-cut tomatoes can be used as a trigger to release antimicrobial garlic oil volatiles from ,-cyclodextrin capsules, reducing microbial growth and the sensory effect of the treatment caused by the free garlic oil. In this context, successful encapsulation in ,-cyclodextrin could stimulate further interest in the use of garlic oil for the control of microbial growth in fresh-cut tomatoes. [source] Encapsulation of nanoparticles by polymerization compounding in a gas/solid fluidized bed reactorAICHE JOURNAL, Issue 9 2009Babak Esmaeili Abstract For the first time, a fluidized bed reactor was used for encapsulating nanoparticles by the polymerization compounding approach using Ziegler,Natta catalysts. The polymerization reaction was carried out using a solvent-free process in a gas-phase reactor. This direct gas,solid reaction greatly simplified collecting the particles of interest after polymerization because none of the extra steps often found in encapsulation processes, such as filtering and drying, were performed in this work. The grafting of the catalyst to the original surface of particles was confirmed by X-ray photoelectron spectroscopy. Micrographs obtained by transmission electron microscopy confirmed the presence of a thin layer of polymer, in the order of a few nanometers, around the particles. The thickness of this coating was affected by the operating conditions of the process. The characterization of the modified particles with electron microscopy also revealed that zirconia nanoparticles tend to be coated in an agglomerated state, whereas aluminum particles were mostly individually encapsulated by the polymer. In addition, the effects of temperature and pressure were studied on the encapsulation process and a kinetic analysis was presented based on the available models in the literature. © 2009 American Institute of Chemical Engineers AIChE J, 2009 [source] Encapsulation of naturally occurring flavonoids into liposomes: physicochemical properties and biological activity against human cancer cell linesJOURNAL OF PHARMACY AND PHARMACOLOGY: AN INTERNATI ONAL JOURNAL OF PHARMACEUTICAL SCIENCE, Issue 10 2004M. Goniotaki Liposomes consisting of egg phosphatidylcholine were prepared by a thin-film hydration method followed by sonication and were used to investigate the percentage encapsulation of four flavonoids (quercetin, rutin, isoscutellarein and isoscutellarein diglycoside). The lipid recovery and the flavonoid-to-lipid molar ratio were measured using high-performance thin-layer chromatography/flame ionization detection and UV-vis spectroscopy. Differential scanning calorimetry was used to study the effect of the flavonoids on the phase transition temperature and on the enthalpy of the main phase transition of dipalmitoylphosphatidylcholine bilayers, and their ability to influence the membrane fluidity. The final liposomal formulation incorporating flavonoids, as well as free flavonoids, were tested for their activity against human cancer cell lines using the sulforhodamine B assay. The results showed that the encapsulation efficiency varied from 95% (0.21 flavonoid-to-lipid molar ratio) to 37.5% (0.09 flavonoid-to-lipid molar ratio) for isoscutellarein and its glycoside, respectively. The differential scanning calorimetry data showed close thermal and dynamic effects depending on the structure of the flavonoids, and suggest that there is a relationship between flavonoid molecular structure and the interaction with model membranes. Liposomal isoscutellarein showed improved growth inhibiting activity against all cell lines tested in comparison with that of its free form, which was inactive (>100 ,M). [source] Inhibition of serum angiotensin-converting enzyme in rabbits after intravenous administration of enalaprilat-loaded intact erythrocytesJOURNAL OF PHARMACY AND PHARMACOLOGY: AN INTERNATI ONAL JOURNAL OF PHARMACEUTICAL SCIENCE, Issue 9 2001Mehrdad Hamidi Encapsulation of drugs in intact erythrocytes, because of the profound characteristics of these natural microspheres, has gained considerable attention in recent years. In this study, the inhibition time courses of serum angiotensin-converting enzyme (ACE) activity after intravenous administration of enalaprilat encapsulated in intact erythrocytes was evaluated and compared with free drug, in a rabbit model. Three groups of animals each received free drug, drug-loaded erythrocytes or sham-encapsulated erythrocytes. Serum ACE activity was determined in each case using the synthetic substrate hippuryl-histidyl-leucine and quantitation of the hippuric acid released by a developed and validated HPLC method. The serum ACE inhibition profiles in the three groups showed that the encapsulated drug inhibited the serum ACE more slowly, more efficiently, over a considerably longer time and in a more reproducible manner, than the free drug or sham-encapsulated erythrocytes. We conclude that the erythrocytes can serve as efficacious slow-release drug carriers for enalaprilat in circulation. [source] The Encapsulation of Bleomycin Within Chitosan Based Polymeric Vesicles Does Not Alter its BiodistributionJOURNAL OF PHARMACY AND PHARMACOLOGY: AN INTERNATI ONAL JOURNAL OF PHARMACEUTICAL SCIENCE, Issue 4 2000J. SLUDDEN Polymeric vesicles have recently been developed from an amphiphilic chitosan derivative,palmitoyl glycol chitosan. Their potential as a drug delivery system was evaluated using the anti-cancer compound bleomycin as a model drug. Palmitoyl glycol chitosan (GCP41) was synthesised by conjugation of palmitoyl groups to glycol chitosan. Bleomycin-containing vesicles (669 nm diameter) were prepared from a mixture of GCP41 and cholesterol by remote loading. The vesicles were imaged by freeze-fracture electron microscopy and their in-vitro stability tested. Incubation of the larger vesicles with plasma in-vitro led to a reduction of mean size by 49%, a reaction not seen with control sorbitan monostearate niosomes (215 nm in size). They also showed a higher initial drug release (1 h), but GCP41 and sorbitan monostearate vesicles retained 62% and 63% of the encapsulated drug after 24 h, respectively. The biodistribution of smaller vesicles (290 nm) prepared by extrusion through a 200-nm filter was also studied in male Balb/c mice. Encapsulation of bleomycin into polymeric vesicles did not significantly alter the pharmacokinetics of biodistribution of bleomycin in male Balb/c mice although plasma and kidney levels were slightly increased. It is concluded that the extruded GCP41 vesicles break down in plasma in-vivo and hence are unlikely to offer any therapeutic advantage over the free drug. [source] Supramolecular encapsulation of 1,3-bis(1-adamantyl)imidazolium chloride by ,-cyclodextrins: towards inhibition of C(2)-H/D exchangeJOURNAL OF PHYSICAL ORGANIC CHEMISTRY, Issue 2 2009Loïc Leclercq Abstract The study of the hydrogen/deuterium exchange reactions of the C(2)-proton for different carbene precursors has been carried out in the absence and presence of ,-cyclodextrin in D2O at 25°C. Formation of the inclusion complexes of imidazolium salts with the native ,-cyclodextrin and the ,-dimethylcyclodextrin is demonstrated by 1D and 2D 1H NMR, ESI/HRMS and a molecular modelling study. Formation of the inclusion complexes of imidazolium salts with the native ,-cyclodextrin and the ,-dimethylcyclodextrin is a simple and efficient method to modify the acidity of the imidazolium H(2) and to modify its environment. Encapsulation of 1,3-disubstituted imidazolium chloride by ,-cyclodextrins results in the inhibition of the H(2)/D exchange in the complex. Copyright © 2008 John Wiley & Sons, Ltd. [source] Encapsulation of nanomaterials using an intermediary layer cross-linkable ABC triblock copolymerJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 19 2009Jin Sook Kim Abstract For the preparation of core-shell nanoparticles containing functional nanomaterials, a photo-cross-linkable amphiphilic ABC triblock copolymer, poly(ethylene glycol)- b -poly(2-cinnamoyloxyethyl methacrylate)- b -poly(methyl methacrylate) (PEG-PCEMA-PMMA), was synthesized. This triblock copolymer was then used to encapsulate Au nanoparticles or pyrene. The triblock copolymer of PEG- b -poly(2-hydroxyethyl methacrylate)- b -PMMA (PEG-PHEMA-PMMA) (Mn = 15,800 g/mol, Mw/Mn = 1.58) was first synthesized by activators generated by electron transfer atom transfer radical polymerization. Its middle block was then functionalized with cinnamoyl chloride. The degrees of polymerization of the PEG, PHEMA, and PMMA blocks were 45, 13, and 98, respectively. PMMA-tethered Au nanoparticles (with an average diameter of 3.0 nm) or pyrene was successfully encapsulated within the PEG-PCEMA-PMMA micelles. The intermediary layers of the micelles were then cross-linked by UV irradiation. The spherical structures of the PEG-PCEMA-PMMA micelles containing Au nanoparticles or pyrene were not changed by the photo-cross-linking process and they showed excellent colloidal stability. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 4963,4970, 2009 [source] Encapsulation of silver nanoparticles within micropores of block copolymers constructed by emulsion-induced methodJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 10 2008Koji Ishizu An encapsulation of silver nanoparticles has been developed based on a template technique. Microporous films containing Ag+ ions were constructed by emulsion micelles of PEO- block- PMMA amphiphilic diblock copolymers. Ag+ ions are located around peripheral PEO phases of micropores. Subsequently, Ag nanoparticles (ca. 23 nm in diameter) within the micropore have been prepared by the addition of a chemical reductant, e.g. NaBH4. [source] | |||||||||||||||||||||||||||||||||||||||||||