JOURNAL OF PROSTHODONTICS, Issue 2 2008
James L. Sheets DDS
Abstract Purpose: The purpose of this study was to assess and compare the retentive nature of common dental cements that have been adapted for use in the implant abutment cement-retained crown (CRC) technique with those specifically formulated for this purpose. Materials and Methods: Ten regular diameter implant analogs were embedded in stainless steel disks. Unmodified CRC abutments were attached and torqued to 30 Ncm. Test crowns were waxed and cast with base metal alloy. Castings were fitted, cleaned with aluminum oxide, and steam cleaned prior to application of the cement. The cements used were: (1) Temp Bond, (2) UltraTemp, regular, (3) UltraTemp firm, (4) ImProv with petroleum jelly coating of crown, (5) ImProv without petroleum jelly, (6) Premier Implant with KY Jelly coating of abutment, (7) Premier Implant without KY jelly, (8) TR-2, (9) Fleck's, (10) Ketac Cem Aplicap, and (11) Fuji Plus Capsule. After cementation, assemblies were stored for 24 hours. Each sample was subjected to a pull-out test using an Instron universal testing machine at a crosshead speed of 5.0 mm/min. Loads required to remove the crowns were recorded, and mean values for each group determined. A one-way ANOVA and a post hoc least square difference (LSD) test were done for pairwise comparison at a confidence interval of 95%. Results: The mean values (±SD) of loads at failure (n = 10) for various cements were as follows (N): Ultratemp, regular 358.6 (±38.2) (Group A), ImProv without petroleum jelly 172.4 (±59.6) (Group B), Fleck's 171.8 (±62.2) (Group B), Ketac Cem 167.8 (±69.1) (Group B), UltraTemp firm 158.8 (±62.7) (Group BC), Fuji Plus 147.5 (±69.7) (Group BC), Premier without KY jelly 131.6 (±31.8) (Group BC), ImProv using petroleum jelly 130.8 (±42.5) (Group BC), Temp Bond 117.8 (±48.3) (Group C), TR-2 41.2 (±16.6) (Group D), and Premier with KY jelly 31.6 (±24.8) (Group D). Groups with the same letter were not significantly different. Conclusions: Within the limitations of this in vitro study, it is not suggested that any one cement is better than another at retaining cement-retained crowns (CRCs) to implant abutments or that a threshold value must be accomplished to ensure retention. The ranking of cements presented is meant to be a discretionary guide for the clinician in deciding the amount of desired retention between castings and implant abutments. [source]

Osteoprotegerin in the Inner Ear May Inhibit Bone Remodeling in the Otic Capsule,

THE LARYNGOSCOPE, Issue 1 2005
Andreas F. Zehnder MD
Abstract Objectives: To elucidate factors that may be responsible for the inhibition of remodeling of bone within the otic capsule. Methods: Expression of osteoprotegerin (OPG), receptor activator of nuclear factor kappa B (RANK), and RANK ligand (RANKL) were assayed in samples of bone obtained from the otic capsule, calvarium, and femur, and from the soft tissue within the cochlea using semiquantitative reverse transcriptase polymerase chain reaction (RT-PCR) in mice. Immunostaining was used for histologic localization of the gene products. An enzyme-linked immunosorbent assay (ELISA) was used to quantify the amount of OPG within perilymph, serum, and cerebrospinal fluid. The micro-anatomy of the interface between the otic capsule and the fluid spaces of the cochlea was investigated by brightfield and phase-contrast microscopy and by three-dimensional reconstruction in the mouse and human. Results: OPG, a powerful inhibitor of bone remodeling, was expressed at extremely high levels within the soft tissue of the cochlea and was present in the perilymph at very high concentrations. The OPG produced within the inner ear may diffuse into the surrounding otic capsule, where it may be responsible for inhibition of bone turnover. Our anatomic studies revealed an extensive system of interconnected canaliculi within the otic capsule that had direct openings into the fluid spaces of the inner ear, thus providing a possible anatomic route for the diffusion of OPG from the inner ear into the surrounding bone. Conclusion: OPG, a potent inhibitor of osteoclast formation and function, is expressed at high levels within the inner ear and is secreted into the perilymph and the surrounding bone and may serve to inhibit active bone remodeling within the otic capsule, especially immediately adjacent to the cochlea. By this means, the cochlear soft tissue may control the nature of the surrounding petrous bone. [source]

Lymphatic Vessels in Pancreatic Islets Implanted Under the Renal Capsule of Rats

AMERICAN JOURNAL OF TRANSPLANTATION, Issue 4 2006
Ö. Källskog
Transplantation of pancreatic islets necessitates an engraftment process, including revascularization of the graft. Studies of graft vasculature have demonstrated that islets become revascularized during the first post-transplant week through an angiogenic process. If this also involves lymphatic vessels is unknown. The aim of the present study was to functionally evaluate if lymphatic vessels, which are absent in endogenous islets, form after islet transplantation. To achieve this, inbred Wistar-Furth rats were transplanted with 250 syngeneic islets under the renal capsule. Intra-vital microscopy of the graft in combination with interstitial injection of Evans Blue was performed 1 week, 1 month or 9,12 months later. In all animals studied, there was drainage through intra-graft lymphatic capillaries emptying into larger lymphatic vessels associated with the renal capsule. The number was slightly lower 1 week post-transplantation. Most of the lymphatic capillaries were present in the graft stroma, rather than interspersed among the endocrine cells. In some animals, we were able to demonstrate dye in regional lymph nodes. We conclude that unlike endogenous islets, islet grafts develop a lymphatic drainage. Its functional importance and characteristics remain to be established. However, it can be speculated that immune reactions may be facilitated by the presence of lymphatic vessels. [source]

Site-Selective Internal Cross-Linking between Mercury(II)-Centered Vertices of an Octahedral Mercury(II) Capsule by a Rod-Shaped Ditopic Ligand,

ANGEWANDTE CHEMIE, Issue 1 2010
Shuichi Hiraoka Dr.
Ein oder zwei stabförmige Bissulfonat-Brückenliganden wurden durch positionsselektive Verdrängung innerer TfO, -Liganden in eine selbstorganisierte HgII -Kapsel eingebaut. Durch einen Ligandenaustausch der verbleibenden inneren TfO, -Liganden wurden TsO, -Liganden im Innern der resultierenden Kapsel angeordnet, in welcher der/die Bissulfonat-Ligand(en) zwei gegenüberliegende HgII -Ecken verbrücken (siehe Bild). Tf=Trifluormethansulfonyl, Ts=p -Toluolsulfonyl. [source]

A Spherical 24,Butyrate Aggregate with a Hydrophobic Cavity in a Capsule with Flexible Pores: Confinement Effects and Uptake,Release Equilibria at Elevated Temperatures,

ANGEWANDTE CHEMIE, Issue 43 2009
Christian Schäffer
Moleküle unter Zwang: Der Einschluss einer Anordnung aus 24,organischen Butyrat-Einheiten (siehe Bild), die mit 72,H-Atomen einen bemerkenswert großen hydrophoben Hohlraum umschließen, in einer porösen Kapsel führt zu interessanten Wechselwirkungen zwischen den eingesperrten Butyraten. Bei Temperaturerhöhung wird die ,Quarantäne" aufgehoben und die Gastspezies können leichter kommen und gehen. [source]

ChemInform Abstract: Vibrational Spectroscopy of a Tetraureidocalix[4]arene Based Molecular Capsule.

CHEMINFORM, Issue 17 2002
Joerg Dormann
Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source]

Chiral Encapsulation by Directional Interactions

CHEMISTRY - A EUROPEAN JOURNAL, Issue 45 2009
Agnieszka Szumna
Abstract The complexation of chiral guests in the cavity of dimeric self-assembled chiral capsule 12 was studied by using NMR spectroscopy and X-ray crystallography. Capsule 12 has walls composed of amino acid backbones forming numerous directional binding sites that are arranged in a chiral manner. The polar character of the interior dictates the encapsulation preferences towards hydrophilic guests and the ability of the capsule to extract guests from water into an organic phase. Chiral discrimination towards hydroxy acids was evaluated by using association constants and competition experiments, and moderate de values were observed (up to 59,%). Complexes with one or two guest molecules in the cavity were formed. For 1:1 complexes, solvent molecules are coencapsulated; this influences guest dynamics and makes the chiral recognition solvent dependent. Reversal of the preferences can be induced by coencapsulation of a nonchiral solvent in the chiral internal environment. For complexes with two guests, filling of the capsule's internal space can be very effective and packing coefficients of up to 70,% can be reached. The X-ray crystal structure of complex 12,((S) -6)2 with well-resolved guest molecules reveals a recognition motif that is based on an extensive system of hydrogen bonds. The optimal arrangement of interactions with the alternating positively and negatively charged groups of the capsule's walls is fulfilled by the guest carboxylic groups acting simultaneously as hydrogen-bond donors and acceptors. An additional guest molecule interacting externally with the capsule reveals a possible entrance mechanism involving a polar gate. In solution, the structural features and dynamic behavior of the D4 -symmetric homochiral capsule were analyzed by variable-temperature NMR spectroscopy and the results were compared with those for the S8 -symmetric heterochiral capsule. [source]

Confinement and Step-Wise Reopening of Channels in an Artificial Cell/Inorganic Capsule: A 7Li NMR Study

CHEMISTRY - A EUROPEAN JOURNAL, Issue 29 2008
Erhard
Lifting the quarantine for cations: The 20 pores of a spherical molybdenum oxide based capsule, dissolved in dimethyl sulfoxide and containing encapsulated Li+ ions, can be plugged completely with formamidinium cations/guests; however, it can be re-opened stepwise by adding water. Exchange/communication between internal and external Li+ and the blockage thereof have been studied by 7Li NMR spectroscopy (see graphic), also with reference to the use of paramagnetic additives. [source]

Peptide Recognition: Encapsulation and ,-Helical Folding of a Nine-Residue Peptide within a Hydrophobic Dimeric Capsule of a Bowl-Shaped Host

CHEMISTRY - A EUROPEAN JOURNAL, Issue 12 2006
Shohei Tashiro
Abstract A dimeric capsule of coordination bowl 1 encapsulated a nine-residue peptide (Trp-Ala-Glu-Ala-Ala-Ala-Glu-Ala-Trp; 2) within the large hydrophobic cavity in water, and stabilized the ,-helical conformation of bound 2. An NMR titration experiment revealed that monomeric bowl 1 recognized two Trp residues at the both terminals of 2 through 1/2=1:1 to 2:1 complexation. The 1:1 and 2:1 species exist in equilibrium even in the presence of excess 1. It was found that the formation of the 2:1 complex, in which two bowls of 1 wrapped the whole of 2, became dominant by the addition of NaNO3 due to the fact that the enhanced ion strength increased the hydrophobic interaction between Trp residues and the cavity of 1. The ,-helical conformation of 2 within the dimeric capsule of 1 was elucidated from detailed NOESY analysis. [source]

Solid-State Anion,Guest Encapsulation by Metallosupramolecular Capsules Made from Two Tetranuclear Copper(II) Complexes

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 29 2007
Emilio 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]

Monodisperse Polymer Capsules: Tailoring Size, Shell Thickness, and Hydrophobic Cargo Loading via Emulsion Templating

ADVANCED FUNCTIONAL MATERIALS, Issue 10 2010
Jiwei Cui
Abstract The preparation of monodisperse polymer (polydopamine, PDA) capsules by a one-step interfacial polymerization of dopamine onto dimethyldiethoxysilane (DMDES) emulsion droplets and removal of the DMDES templates with ethanol is reported. The diameters of the PDA capsules can be tailored from 400,nm to 2.4,µm by varying either the DMDES emulsion condensation time or the emulsion concentration used for templating. Further, capsules with defined nanometer-scale shell thicknesses (ranging from ,10 to 30,nm) can be prepared by adjusting the emulsion concentration. This shell thickness can be increased by repeated interfacial polymerization of dopamine, with three cycles yielding capsules with a shell thickness of up to 140,nm (for a 0.6% v/v suspension). Functional substances, such as organically stabilized magnetic (Fe3O4) nanoparticles, quantum dots (CdSe/CdS), and hydrophobic drugs (thiocoraline), can be preloaded in the emulsion droplets, and following PDA coating and DMDES removal, these materials remain encapsulated in the polymer capsules. All of the unloaded and loaded PDA capsules are monodisperse and do not aggregate. This work provides new avenues for the preparation of polymer capsules with defined size and shell thickness and for the encapsulation of a range of hydrophobic substances. [source]

Microgel-Based Stimuli-Responsive Capsules

ADVANCED FUNCTIONAL MATERIALS, Issue 4 2009
Sebastian Berger
Abstract In this paper, a preparation of stimuli-responsive capsules based on aqueous microgels is described. Microgel particles act as stabilizers for oil-in-water emulsion and organize themselves on the surface of chloroform droplets containing the biodegradable polymer poly(4-hydroxybutyrate- co -4-hydroxyvalerate) (PHBV). After chloroform evaporation, composite capsules consisting of a thin PHBV wall with integrated microgels are obtained. Due to the presence of microgels acting as sensitive building blocks, the capsules respond to different stimuli (temperature, solvent concentration). Preliminary results indicate that the capsule dimensions and morphology can be tuned by microgel and PHBV concentration in water and chloroform, respectively. [source]

Fabrication of Organized Porphyrin-Nanotube-Attached Heat-Sensitive Polyelectrolyte Capsules,

ADVANCED FUNCTIONAL MATERIALS, Issue 16 2006
S. Sadasivan
Abstract A facile method of connecting fluorescent meso -tetrakis(4-sulfonatophenyl)porphine tetranion nanotubes to polyelectrolyte capsules is developed. Heat-sensitive robust polyelectrolyte capsules consisting of poly(diallyldimethylammonium chloride) and poly(styrene sulfonate) multilayers have been fabricated using the conventional layer-by-layer technique. Supramolecular aggregation of porphyrin monomers to nanotubes is induced in the microenvironment of the capsules by sequential addition of salt and acid. Scanning electron microscopy, transmission electron microscopy, and atomic force microscopy images reveal satellite-like structures consisting of a central capsule core with porphyrin nanotubes emerging radially from the capsule walls. The growth and the distribution of the porphyrin units have been monitored by UV-vis spectroscopy, fluorescence spectroscopy, and confocal laser scanning microscopy. Changing the temperature alters the dimensions and the arrangement of the nanotubes on the capsule walls. Such an attachment of porphyrin tubes onto robust functional capsules should help in developing an artificial light-harvesting system. [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 2005
Mater.
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 2005
W. 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 Delivery

ADVANCED MATERIALS, Issue 38 2010
Yajun 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]

Stimuli-Responsive Porous Hydrogels at Interfaces for Molecular Filtration, Separation, Controlled Release, and Gating in Capsules and Membranes

ADVANCED MATERIALS, Issue 31 2010
Ihor Tokarev
Abstract A continuously growing area of controlled and tunable transport and separation of biomolecules and drugs has recently attracted attention to the structures which can be referred to as stimuli-responsive porous hydrogel thin films. Because of spatial constraints, swelling/shrinking of the hydrogel films results in closing/opening (or vice versa) of the film's pores. Such responsive systems can be used in the configuration of plane films or capsules. The combination of a low thickness (translating into a low hydrodynamic flow resistance and rapid response) with well-defined size and shape of pores (translating into better control of transport and separation), which can be closed, opened, or tuned by an external signal (allowing a large amplitude of changes in diffusivity of solutes in the thin film and a precise control of the pore size), makes these materials very attractive for a range of applications, such as molecular filtration, separation, drug delivery, sensors, and actuators. [source]

Synthesis of Monodisperse Colloidal Spheres, Capsules, and Microballoons by Emulsion Templating,

ADVANCED MATERIALS, Issue 7 2005
I. Zoldesi
New types of monodisperse, micrometer-sized, hollow particles (see Figure) are obtained by encapsulation of emulsion droplets in solid shells and dissolution of the cores. A facile fabrication method is used in which, by simply tuning the thickness of the shells, different types of particles with tunable properties are obtained. [source]

Capillary Zone Electrophoresis and Micellar Electrokinetic Capillary Chromatography for Determining Water-Soluble Vitamins in Commercial Capsules and Tablets

JOURNAL OF FOOD SCIENCE, Issue 1 2001
S-C. Su
ABSTRACT: A rapid method was developed for simultaneously determining thiamine, riboflavin, pyridoxine, nicotinamide, nicotinic acid, and ascorbic acid. It was tested on 15 samples. The peaks of all components were cleanly separated with good resolution by capillary zone electrophoresis (CZE) and micellar electrokinetic chromatography (MECC). CZE was performed with 0.02 M borate buffer, and MECC was performed with 4% acetonitrile in 0.02 M borate/phosphate buffer containing 0.1 M sodium dodecyl sulfate. Average recoveries for all components were 80.3% to 103.7% with coefficients of variation being less than 5%. Thiamine, nicotinic acid, and pyridoxine contents were consistent with those labeled on the packages, but nicotinamide, riboflavin, and ascorbic acid contents of some samples were less. [source]

Hollow polylactide microcapsules with controlled morphology and thermal and mechanical properties

AICHE JOURNAL, Issue 11 2009
Hassan Sawalha
Abstract Hollow polylactide microcapsules were prepared by multistage premix membrane emulsification of polylactide/dichloromethane/oil solutions in water (nonsolvent). The effects of the different oils on the morphology, thermal, and mechanical properties of the hollow microcapsules were investigated. All oils resulted in hollow microcapsules with controlled shell thickness of ,60 nm except for eugenol, in which irregular, massive capsules were obtained. The properties of the microcapsules were strongly dependent on the oil used, for example the thermal transition temperatures found for hollow capsules were lower than for solid particles prepared without any oil. The crystallinity and transition temperatures of the capsules prepared with linear alkanes were higher than for cyclic alkanes; terpenes gave the lowest transition temperatures. The shell stiffness, measured with atomic force microscopy, was highly dependent on the oil used. Capsules prepared with dodecane showed higher stiffness (3.3 N m,1) than with limonene (2 N m,1) or cyclohexane (1.4 N m,1). © 2009 American Institute of Chemical Engineers AIChE J, 2009 [source]

Colon Delivery Efficiencies of Intestinal Pressure-controlled Colon Delivery Capsules Prepared by a Coating Machine in Human Subjects

JOURNAL OF PHARMACY AND PHARMACOLOGY: AN INTERNATI ONAL JOURNAL OF PHARMACEUTICAL SCIENCE, Issue 10 2000
ZHAOPENG HU
Large quantities of pressure-controlled colon delivery capsules (PCDCs) were prepared by a Hicoater-mini pharmaceutical coating machine and colon delivery efficiencies were evaluated in man. Caffeine powder as a model drug was suspended with a polyethylene glycol (PEG) 1000 suppository base at 50°C, and was hardened in no. 0- and no. 2-sized capsular shapes. The capsule-shaped suppositories were coated with 5% w/v ethanolic ethylcellulose (7G grade) solution using the coating machine. By increasing the coating weight of ethylcellulose from 28.6 ± 1.1 mg to 45.3 ± 0.2 mg, the mean coating thickness of no. 0 PCDCs increased from 56 ± 1 ,m to 64 ± 1 ,m. With no. 2 PCDCs, the mean coating thickness increased from 50 ± 1 ,m to 57 ± 1 ,m by increasing the coating weight of ethylcellulose from 8.1 ± 0.5 mg to 11.2 ± 0.3 mg. The no. 0 PCDCs, having a mean ethylcellulose coating membrane thicknesses of 56± 1 ,m (type 1) and 64 ± 1 ,m (type 2), as well as no. 2 PCDCs, having thicknesses of 50 ± 1 ,m (type 3) and 57 ± 1 ,m (type 4), were used for in-vivo evaluation in man. After oral administration of test preparations containing 75 mg of caffeine, saliva samples were obtained and salivary caffeine levels were measured by an HPLC method. The first appearance time, Ti, of caffeine in the saliva was used as a parameter for the estimation of the release time of caffeine from PCDCs in the gastrointestinal tract. The mean Ti values of no. 0 PCDCs were 3.3 ± 0.3 h for type-1 and 5.3 ± 0.3 h for type-2 preparations while the mean Ti values of no. 2 PCDCs were 4.3 ± 0.5 h for type 3 and 5.3 ± 0.3 h for type 4. There were good correlations between ethylcellulose coating membrane thicknesses and in-vivo Ti values. A colon arrival time of 5 h was reported in our subjects by gastrointestinal magnetomarkergraphy. PCDCs having a mean coating thickness of 64± 1 ,m for no. 0 capsules and of 57 ± 1 ,m for no. 2 capsules were thought to deliver caffeine to the human colon efficiently. [source]

Design of a Microfluidic System to Investigate the Mechanical Properties of Layer-by-Layer Fabricated Capsules

MACROMOLECULAR MATERIALS & ENGINEERING, Issue 12 2003
Michelle Prevot
Abstract A microfluidic system was designed, fabricated and implemented to study the behavior of polyelectrolyte capsules flowing in microscale channels. The device contains microchannels that lead into constrictions intended to capture polyelectrolyte microcapsules which were fabricated with the well-known layer-by-layer (LbL) assembly technique. The behavior of hollow capsules at the constrictions was visualized and the properties of the capsules were investigated before and after introduction into the device. Time series of video frames showing capsules being compressed into a constriction. [source]

Red Blood Cell Templated Polyelectrolyte Capsules: A Novel Vehicle for the Stable Encapsulation of DNA and Proteins

MACROMOLECULAR RAPID COMMUNICATIONS, Issue 6 2006
Oliver Kreft
Abstract Summary: A novel method for the encapsulation of biomacromolecules, such as nucleic acids and proteins, into polyelectrolyte microcapsules is described. Fluorescence-labelled double-stranded DNA and human serum albumin (HSA) are used as model substances for encapsulation in hollow microcapsules templated on human erythrocytes. The encapsulation procedure involves an intermediate drying step. The accumulation of DNA and HSA in the capsules is observed by confocal laser scanning microscopy, UV spectroscopy, and fluorimetry. The mechanism of encapsulation is discussed. Confocal fluorescence microscopy images of encapsulated TRITC-HSA (left) and dsDNA (right). Inserts demonstrate fluorescence profiles for both compounds. [source]

Capsule Treatments to Enhance Seedling Emergence of Gaura neomexicana ssp. coloradensis

RESTORATION ECOLOGY, Issue 1 2005
L. M. Burgess
Abstract Management of riparian vegetation is difficult because these communities are frequently impacted by herbivores, invasive weeds, and altered hydrologic regimes. Multiple and intertwined factors affecting rare species recruitment are particularly difficult to identify. Gaura neomexicana ssp. coloradensis Munz (Gaura) is a short-lived perennial forb endemic to riparian areas in mixed-grass prairies of Wyoming, Nebraska, and Colorado, U.S.A. It became a federally listed threatened species in October 2000. Because the species is a recruitment-limited monocarpic perennial, we studied the effects of six capsule-collection dates, a 2-month cool-moist stratification, 24-hr leaching, and 24-hr imbibition on Gaura seedling emergence. Seedling emergence did not vary with collection date. Capsules collected from Gaura plants grown at the Bridger Plant Materials Center in Montana exhibited greater emergence than capsules harvested from endemic populations near Cheyenne, Wyoming, suggesting that maternal plant growing conditions impact dormancy. Because cool-moist stratification enhanced seedling emergence of Gaura and leaching did not, sufficient moisture during cool temperatures may be more critical than leaching of germination inhibitors as might occur with normal stream flows. Spring flooding may enhance Gaura recruitment by increasing the availability of riparian sites that are inundated during periods of cool temperatures. If so, hydrologic and climatic regimes must be considered in restoring the unique conditions needed for germination of this rare riparian endemic. [source]

Porous Capsules {(M)M5}12FeIII30 (M=MoVI, WVI): Sphere Surface Supramolecular Chemistry with 20 Ammonium Ions, Related Solution Properties, and Tuning of Magnetic Exchange Interactions,

ANGEWANDTE CHEMIE, Issue 3 2010
Maria Todea Dr.
Eine Vielfalt von Wasserstoffbrücken-Bindungsoptionen auf einer hochfunktionalisierten Kapseloberfläche mit 20 kronenetherartigen Poren ermöglicht die Fixierung/Erkennung von 20 Ammoniumionen (siehe Bild; W grün, Fe orange, O rot, N blau, H hellgrau), die in Lösung zum Teil abgegeben werden, und zwar unter Bildung entsprechender Gleichgewichte. [source]

ChemInform Abstract: Porous Capsules {(M)M5}12FeIII30 (M: MoVI, WVI): Sphere Surface Supramolecular Chemistry with 20 Ammonium Ions, Related Solution Properties, and Tuning of Magnetic Exchange Interactions.

CHEMINFORM, Issue 15 2010
Achim Mueller
Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source]

Porous Inorganic Capsules in Action: Modelling Transmembrane Cation-Transport Parameter-Dependence Based on Water as Vehicle.

CHEMINFORM, Issue 45 2005
Erhard T. K. Haupt
Abstract For Abstract see ChemInform Abstract in Full Text. [source]

Noncovalent Isotope Effect for Guest Encapsulation in Self-Assembled Molecular Capsules

CHEMISTRY - A EUROPEAN JOURNAL, Issue 4 2010
Takeharu Haino Prof.
No abstract is available for this article. [source]

pH-Controlled Molecular Switches and the Substrate-Directed Self-Assembly of Molecular Capsules with a Calix[4]pyrrole Derivative

CHEMISTRY - A EUROPEAN JOURNAL, Issue 36 2008
Grazia Cafeo Dr.
Abstract 10,,20,-Bis(4-nitrophenyl)calix[4]pyrrole (1) forms 1:1 complexes with anions of selected aromatic hydroxy acids in which the host orientation within the guest is controlled by a change in the pH,value. Some bis-anionic guests, including those obtained from 4-hydroxybenzoic acid, 1,4- and 1,3-benzenedicarboxylic acids, induce the self-assembly of molecular capsules involving two molecules of the receptor. 1H,NMR data and solid-state structures of the 1:1 complex of 1 with p -C6H4(COOH)(COO,)+NMe4 and the 2:1 capsule [(1)2m -C6H4(COO,)2(+NMe4)2] provide structural details in solution and in the solid state. [source]

Photoinduced Reduction of Silver inside Microscale Polyelectrolyte Capsules

CHEMPHYSCHEM, Issue 10 2003
Dmitry G. Shchukin Dr.
Every cloud has a silver lining. The use of poly(styrene sulfonate)/poly(allylamine hydrochloride) (PSS/PAH) polyelectrolyte capsules as microreactors is described for the photochemical synthesis of nanosized silver particles, exclusively, inside a restricted volume of capsule (see graphic). The formed Ag nanoparticles are not aggregated and have an average diameter of 8 nm. The resulting Ag-filled polyelectrolyte capsules can find applications as catalytic microreactors and medical agents. [source]