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Sample records for microcapsules encapsulating reconfigurable

  1. Silk sericin-alginate-chitosan microcapsules: hepatocytes encapsulation for enhanced cellular functions.

    PubMed

    Nayak, Sunita; Dey, Sanchareeka; Kundu, Subhas C

    2014-04-01

    The encapsulation based technology permits long-term delivery of desired therapeutic products in local regions of body without the need of immunosuppressant drugs. In this study microcapsules composed of sericin and alginate micro bead as inner core and with an outer chitosan shell are prepared. This work is proposed for live cell encapsulation for potential therapeutic applications. The sericin protein is obtained from cocoons of non-mulberry silkworm Antheraea mylitta. The sericin-alginate micro beads are prepared via ionotropic gelation under high applied voltage. The beads further coated with chitosan and crosslinked with genipin. The microcapsules developed are nearly spherical in shape with smooth surface morphology. Alamar blue assay and confocal microscopy indicate high cell viability and uniform encapsulated cell distribution within the sericin-alginate-chitosan microcapsules indicating that the microcapsules maintain favourable microenvironment for the cells. The functional analysis of encapsulated cells demonstrates that the glucose consumption, urea secretion rate and intracellular albumin content increased in the microcapsules. The study suggests that the developed sericin-alginate-chitosan microcapsule contributes towards the development of cell encapsulation model. It also offers to generate enriched population of metabolically and functionally active cells for the future therapeutics especially for hepatocytes transplantation in acute liver failure. PMID:24486492

  2. Direct encapsulation of water-soluble drug into silica microcapsules for sustained release applications

    SciTech Connect

    Wang Jiexin; Wang Zhihui; Chen Jianfeng Yun, Jimmy

    2008-12-01

    Direct encapsulation of water-soluble drug into silica microcapsules was facilely achieved by a sol-gel process of tetraethoxysilane (TEOS) in W/O emulsion with hydrochloric acid (HCl) aqueous solution containing Tween 80 and drug as well as cyclohexane solution containing Span 80. Two water-soluble drugs of gentamicin sulphate (GS) and salbutamol sulphate (SS) were chosen as model drugs. The characterization of drug encapsulated silica microcapsules by scanning electronic microscopy (SEM), FTIR, thermogravimetry (TG) and N{sub 2} adsorption-desorption analyses indicated that drug was successfully entrapped into silica microcapsules. The as-prepared silica microcapsules were uniform spherical particles with hollow structure, good dispersion and a size of 5-10 {mu}m, and had a specific surface area of about 306 m{sup 2}/g. UV-vis and thermogravimetry (TG) analyses were performed to determine the amount of drug encapsulated in the microcapsules. The BJH pore size distribution (PSD) of silica microcapsules before and after removing drug was examined. In vitro release behavior of drug in simulated body fluid (SBF) revealed that such system exhibited excellent sustained release properties.

  3. Hydrogel Encapsulation of Cells in Core-Shell Microcapsules for Cell Delivery.

    PubMed

    Nguyen, Duy Khiem; Son, Young Min; Lee, Nae-Eung

    2015-07-15

    A newly designed 3D core-shell microcapsule structure composed of a cell-containing liquid core and an alginate hydrogel shell is fabricated using a coaxial dual-nozzle electrospinning system. Spherical alginate microcapsules are successfully generated with a core-shell structure and less than 300 μm in average diameter using this system. The thickness of the core and shell can be easily controlled by manipulating the core and shell flow rates. Cells encapsulated in core-shell microcapsules demonstrate better cell encapsulation and immune protection than those encapsulated in microbeads. The observation of a high percentage of live cells (≈80%) after encapsulation demonstrates that the voltage applied for generation of microcapsules does not significantly affect the viability of encapsulated cells. The viability of encapsulated cells does not change even after 3 d in culture, which suggests that the core-shell structure with culture medium in the core can maintain high cell survival by providing nutrients and oxygen to all cells. This newly designed core-shell structure can be extended to use in multifunctional platforms not only for delivery of cells but also for factor delivery, imaging, or diagnosis by loading other components in the core or shell. PMID:25963828

  4. Cagelike mesoporous silica encapsulated with microcapsules for immobilized laccase and 2, 4-DCP degradation.

    PubMed

    Yang, Junya; Huang, Yan; Yang, Yuxiang; Yuan, Hongming; Liu, Xiangnong

    2015-12-01

    In this study, cage-like mesoporous silica was used as the carrier to immobilize laccase by a physical approach, followed by encapsulating with chitosan/alginate microcapsule membranes to form microcapsules of immobilized laccase based on layer-by-layer technology. The relationship between laccase activity recovery/leakage rate and the coating thickness was simultaneously investigated. Because the microcapsule layers have a substantial network of pores, they act as semipermeable membranes, while the laccase immobilized inside the microcapsules acts as a processing plant for degradation of 2,4-dichlorophenol. The microcapsules of immobilized laccase were able to degrade 2,4-dichlorophenol within a wide range of 2,4-dichlorophenol concentration, temperature and pH, with mean degradation rate around 62%. Under the optimal conditions, the thermal stability and reusability of immobilized laccase were shown to be improved significantly, as the removal rate and degradation rate remained over 40.2% and 33.8% respectively after 6cycles of operation. Using mass spectrometry (MS) and nuclear magnetic resonance (NMR), diisobutyl phthalate and dibutyl phthalate were identified as the products of 2,4-dichlorophenol degradation by the microcapsules of immobilized laccase and laccase immobilized by a physical approach, respectively, further demonstrating the degradation mechanism of 2,4-dichlorophenol by microcapsule-immobilized laccase. PMID:26702968

  5. Microfluidics-assisted engineering of polymeric microcapsules with high encapsulation efficiency for protein drug delivery.

    PubMed

    Pessi, Jenni; Santos, Hélder A; Miroshnyk, Inna; JoukoYliruusi; Weitz, David A; Mirza, Sabiruddin

    2014-09-10

    In this study, microfluidic technology was employed to develop protein formulations. The microcapsules were produced with a biphasic flow to create water-oil-water (W/O/W) double emulsion droplets with ultrathin shells. Optimized microcapsule formulations containing 1% (w/w) bovine serum albumin (BSA) in the inner phase were prepared with poly(vinyl alcohol), polycaprolactone and polyethylene glycol. All the particles were found to be intact and with a particle size of 23-47 μm. Furthermore, the particles were monodisperse, non-porous and stable up to 4 weeks. The encapsulation efficiency of BSA in the microcapsules was 84%. The microcapsules released 30% of their content within 168 h. This study demonstrates that microfluidics is a powerful technique for engineering formulations for therapeutic proteins. PMID:24928131

  6. Encapsulated eucalyptus oil in ionically cross-linked alginate microcapsules and its controlled release.

    PubMed

    Noppakundilograt, Supaporn; Piboon, Phianghathai; Graisuwan, Wilaiporn; Nuisin, Roongkan; Kiatkamjornwong, Suda

    2015-10-20

    Sodium alginate microcapsules containing eucalyptus oil were prepared by oil-in-water emulsification via Shirasu porous glass (SPG) membrane and cross-linked by calcium chloride (CaCl2). SPG membrane pore size of 5.2μm was used to control the size of eucalyptus oil microdroplets. Effects of sodium alginate, having a mannuronic acid/guluronic acid (M/G) ratio of 1.13, eucalyptus oil and CaCl2 amounts on microdroplet sizes and size distribution were elucidated. Increasing sodium alginate amounts from 0.1 to 0.5% (wv(-1)) sodium alginate, the average droplets size increased from 42.2±2.0 to 48.5±0.6μm, with CVs of 16.5±2.2 and 30.2±4.5%, respectively. CaCl2 successfully gave narrower size distribution of cross-linked eucalyptus oil microcapsules. The optimum conditions for preparing the microcapsules, oil loading efficiency, and controlled release of the encapsulated eucalyptus oil from the microcapsules as a function of time at 40°C were investigated. Release model for the oil from microcapsules fitted Ritger-Peppas model with non-Fickian transport mechanism. PMID:26256156

  7. Fibronectin-Alginate microcapsules improve cell viability and protein secretion of encapsulated Factor IX-engineered human mesenchymal stromal cells.

    PubMed

    Sayyar, Bahareh; Dodd, Megan; Marquez-Curtis, Leah; Janowska-Wieczorek, Anna; Hortelano, Gonzalo

    2015-01-01

    Continuous delivery of proteins by engineered cells encapsu-lated in biocompatible polymeric microcapsules is of considerable therapeutic potential. However, this technology has not lived up to expectations due to inadequate cell--matrix interactions and subsequent cell death. In this study we hypoth-esize that the presence of fibronectin in an alginate matrix may enhance the viability and functionality of encapsulated human cord blood-derived mesenchymal stromal cells (MSCs) expressing the human Factor IX (FIX) gene. MSCs were encapsulated in alginate-PLL microcapsules containing 10, 100, or 500 μg/ml fibronectin to ameliorate cell survival. MSCs in microcapsules with 100 and 500 μg/ml fibronectin demonstrated improved cell viability and proliferation and higher FIX secretion compared to MSCs in non-supplemented microcapsules. In contrast, 10 μg/ml fibronectin did not significantly affect the viability and protein secretion from the encapsulated cells. Differentiation studies demonstrated osteogenic (but not chondrogenic or adipogenic) differentiation capability and efficient FIX secretion of the enclosed MSCs in the fibronectin-alginate suspension culture. Thus, the use of recombinant MSCs encapsulated in fibronectin-alginate microcapsules in basal or osteogenic cultures may be of practical use in the treatment of hemophilia B. PMID:24564349

  8. Encapsulation of flaxseed oil using a benchtop spray dryer for legume protein-maltodextrin microcapsule preparation.

    PubMed

    Can Karaca, Asli; Low, Nicholas; Nickerson, Michael

    2013-05-29

    Flaxseed oil was microencapsulated employing a wall material matrix of either chickpea (CPI) or lentil protein isolate (LPI) and maltodextrin using a benchtop spray dryer. Effects of emulsion formulation (oil, protein and maltodextrin levels) and protein source (CPI vs LPI) on the physicochemical characteristics, oxidative stability, and release properties of the resulting capsules were investigated. Microcapsule formulations containing higher oil levels (20% oil, 20% protein, 60% maltodextrin) were found to have higher surface oil and lower encapsulation efficiencies. Overall, LPI-maltodextrin capsules gave higher flaxseed oil encapsulation efficiencies (∼88.0%) relative to CPI-maltodextrin matrices (∼86.3%). However, both designs were found to provide encapsulated flaxseed oil protection against oxidation over a 25 d room temperature storage study relative to free oil. Overall, ∼37.6% of encapsulated flaxseed oil was released after 2 h under simulated gastric fluid, followed by the release of an additional ∼46.6% over a 3 h period under simulated intestinal fluid conditions. PMID:23663097

  9. Encapsulation of methotrexate loaded magnetic microcapsules for magnetic drug targeting and controlled drug release

    NASA Astrophysics Data System (ADS)

    Chakkarapani, Prabu; Subbiah, Latha; Palanisamy, Selvamani; Bibiana, Arputha; Ahrentorp, Fredrik; Jonasson, Christian; Johansson, Christer

    2015-04-01

    We report on the development and evaluation of methotrexate magnetic microcapsules (MMC) for targeted rheumatoid arthritis therapy. Methotrexate was loaded into CaCO3-PSS (poly (sodium 4-styrenesulfonate)) doped microparticles that were coated successively with poly (allylamine hydrochloride) and poly (sodium 4-styrenesulfonate) by layer-by-layer technique. Ferrofluid was incorporated between the polyelectrolyte layers. CaCO3-PSS core was etched by incubation with EDTA yielding spherical MMC. The MMC were evaluated for various physicochemical, pharmaceutical parameters and magnetic properties. Surface morphology, crystallinity, particle size, zeta potential, encapsulation efficiency, loading capacity, drug release pattern, release kinetics and AC susceptibility studies revealed spherical particles of ~3 μm size were obtained with a net zeta potential of +24.5 mV, 56% encapsulation and 18.6% drug loading capacity, 96% of cumulative drug release obeyed Hixson-Crowell model release kinetics. Drug excipient interaction, surface area, thermal and storage stability studies for the prepared MMC was also evaluated. The developed MMC offer a promising mode of targeted and sustained release drug delivery for rheumatoid arthritis therapy.

  10. Coaxial electrospray of liquid core-hydrogel shell microcapsules for encapsulation and miniaturized 3D culture of pluripotent stem cells

    PubMed Central

    Zhao, Shuting; Agarwal, Pranay; Rao, Wei; Huang, Haishui; Zhang, Renliang; Liu, Zhenguo; Yu, Jianhua; Weisleder, Noah; Zhang, Wujie; He, Xiaoming

    2014-01-01

    A novel coaxial electrospray technology is developed to generate microcapsules with a hydrogel shell of alginate and an aqueous liquid core of living cells using two aqueous fluids in one step. Approximately 50 murine embryonic stem (ES) cells encapsulated in the core with high viability (92.3 ± 2.9%) can proliferate to form a single ES cell aggregate of 128.9 ± 17.4 μm in each microcapsule within 7 days. Quantitative analyses of gene and protein expression indicate that ES cells cultured in the miniaturized 3D liquid core of the core-shell microcapsules have significantly higher pluripotency on average than the cells cultured on 2D substrate or in the conventional 3D alginate hydrogel microbeads without a core-shell architecture. The higher pluripotency is further suggested by their significantly higher capability of differentiation into beating cardiomyocytes and higher expression of cardiomyocyte specific gene markers on average after directed differentiation under the same conditions. Considering its wide availability, easiness to set up and operate, reusability, and high production rate, the novel coaxial electrospray technology together with the microcapsule system is of importance for mass production of ES cells with high pluripotency to facilitate translation of the emerging pluripotent stem cell-based regenerative medicine into the clinic. PMID:25036382

  11. Rapid one-step purification of single-cells encapsulated in alginate microcapsules from oil to aqueous phase using a hydrophobic filter paper: implications for single-cell experiments.

    PubMed

    Lee, Do-Hyun; Jang, Miran; Park, Je-Kyun

    2014-10-01

    By virtue of the biocompatibility and physical properties of hydrogel, picoliter-sized hydrogel microcapsules have been considered to be a biometric signature containing several features similar to that of encapsulated single cells, including phenotype, viability, and intracellular content. To maximize the experimental potential of encapsulating cells in hydrogel microcapsules, a method that enables efficient hydrogel microcapsule purification from oil is necessary. Current methods based on centrifugation for the conventional stepwise rinsing of oil, are slow and laborious and decrease the monodispersity and yield of the recovered hydrogel microcapsules. To remedy these shortcomings we have developed a simple one-step method to purify alginate microcapsules, containing a single live cell, from oil to aqueous phase. This method employs oil impregnation using a commercially available hydrophobic filter paper without multistep centrifugal purification and complicated microchannel networks. The oil-suspended alginate microcapsules encapsulating single cells from mammalian cancer cell lines (MCF-7, HepG2, and U937) and microorganisms (Chlorella vulgaris) were successfully exchanged to cell culture media by quick (~10 min) depletion of the surrounding oil phase without coalescence of neighboring microcapsules. Cell proliferation and high integrity of the microcapsules were also demonstrated by long-term incubation of microcapsules containing a single live cell. We expect that this method for the simple and rapid purification of encapsulated single-cell microcapsules will attain widespread adoption, assisting cell biologists and clinicians in the development of single-cell experiments. PMID:25130499

  12. Long-term function of islets encapsulated in a re-designed alginate microcapsule construct in omentum pouches of immune-competent diabetic rats

    PubMed Central

    Pareta, Rajesh; McQuilling, John P; Sittadjody, Sivanandane; Jenkins, Randy; Bowden, Stephen; Orlando, Giuseppe; Farney, Alan C; Brey, Eric M; Opara, Emmanuel C

    2014-01-01

    Objectives Our study aim was to determine encapsulated islet graft viability in an omentum pouch and the effect of FGF-1 released from our redesigned alginate microcapsules on the function of the graft. Methods Isolated rat islets were encapsulated in an inner core made with 1.5% low-viscosity high-mannuronic acid (LVM) alginate followed by an external layer made with 1.25% low-viscosity high-guluronic acid (LVG) alginate with or without FGF-1, in microcapsules measuring 300 – 400 μm in diameter. The two alginate layers were separated by a perm-selective membrane made with 0.1 % Poly-L-Ornithine (PLO), and the inner LVM core was partially chelated using 55 mM sodium citrate for 2 min. Results A marginal mass of encapsulated islet allografts (~2000 islets/kg) in Streptozotocin-diabetic Lewis rats caused significant reduction in blood glucose levels similar to the effect observed with encapsulated islet isografts. Transplantation of allo-islets co-encapsulated with FGF-1 did not result in better glycemic control, but induced greater body weight maintenance in transplant recipients compared to those that received only allo-islets. Histological examination of the retrieved tissue demonstrated morphologically and functionally intact islets in the microcapsules, with no signs of fibrosis. Conclusion We conclude that the omentum is a viable site for encapsulated islet transplantation. PMID:24681880

  13. Performance of biodegradable microcapsules of poly(butylene succinate), poly(butylene succinate-co-adipate) and poly(butylene terephthalate-co-adipate) as drug encapsulation systems.

    PubMed

    Brunner, Cornelia Theresa; Baran, Erkan Türker; Pinho, Elisabete Duarte; Reis, Rui Luís; Neves, Nuno Meleiro

    2011-06-01

    Poly(butylene succinate) (PBSu), poly(butylene succinate-co-adipate) (PBSA) and poly(butylene terephthalate-co-adipate) (PBTA) microcapsules were prepared by the double emulsion/solvent evaporation method. The effect of polymer and poly(vinyl alcohol) (PVA) concentration on the microcapsule morphologies, drug encapsulation efficiency (EE) and drug loading (DL) of bovine serum albumin (BSA) and all-trans retinoic acid (atRA) were all investigated. As a result, the sizes of PBSu, PBSA and PBTA microcapsules were increased significantly by varying polymer concentrations from 6 to 9%. atRA was encapsulated into the microcapsules with an high level of approximately 95% EE. The highest EE and DL of BSA were observed at 1% polymer concentration in values of 60 and 37%, respectively. 4% PVA was found as the optimum concentration and resulted in 75% EE and 14% DL of BSA. The BSA release from the capsules of PBSA was the longest, with 10% release in the first day and a steady release of 17% until the end of day 28. The release of atRA from PBSu microcapsules showed a zero-order profile for 2 weeks, keeping a steady release rate during 4 weeks with a 9% cumulative release. Similarly, the PBSA microcapsules showed a prolonged and a steady release of atRA during 6 weeks with 12% release. In the case of PBTA microcapsules, after a burst release of 10% in the first day, showed a parabolic release profile of atRA during 42 days, releasing 36% of atRA. PMID:21376545

  14. Microfluidic preparation of a highly active and stable catalyst by high performance of encapsulation of polyvinylpyrrolidone (PVP)-Pt nanoparticles in microcapsules.

    PubMed

    Nam, Jin-Oh; Kim, Jongmin; Jin, Si Hyung; Chung, Young-Min; Lee, Chang-Soo

    2016-02-15

    The encapsulation of active metals in microcapsules would be highly advantageous in maintaining or improving the reaction performance of an array of widely used chemical reactions. However, conventional methods suffer from low uniformity, complicated fabrication steps, sintering, leaching, decline of catalytic activity, and/or poor reusability. Here, we report an efficient microfluidic approach to encapsulate Pt nanoparticle stabilized by polyvinylpyrrolidone (PVP) in photocurable double-emulsion droplets with semipermeable thin shells. The encapsulated catalysts are prepared by the in situ photopolymerization of a double emulsion. The rapid and exquisite microfluidics-based fabrication process successfully generates monodisperse microcapsules without loss of the PVP-Pt nanoparticles, which is the first demonstration of the microfluidic encapsulation of active metal with promising catalytic activity. Specifically, compared to quasi-homogeneous catalysis of PVP-Pt nanoparticles for 4-nitrophenol hydrogenation, the encapsulated PVP-Pt nanoparticles demonstrate excellent catalytic activity, a leaching-proof nature, and high reusability under the same reaction conditions. We envision that the approach described here may be an example of elegant catalyst design to efficiently overcome difficult problems in active-metal encapsulation and to dramatically enhance catalytic activity by taking advantage of the unique aspects of microfluidic methods. PMID:26624530

  15. Biofriendly bonding processes for nanoporous implantable SU-8 microcapsules for encapsulated cell therapy

    PubMed Central

    Nemani, Krishnamurthy; Kwon, Joonbum; Trivedi, Krutarth; Hu, Walter; Lee, Jeong-Bong; Gimi, Barjor

    2013-01-01

    Mechanically robust, cell encapsulating microdevices fabricated using photolithographic methods can lead to more efficient immunoisolation in comparison to cell encapsulating hydrogels. There is a need to develop adhesive bonding methods which can seal such microdevices under physiologically friendly conditions. We report the bonding of SU-8 based substrates through (i) magnetic self assembly, (ii) using medical grade photocured adhesive and (iii) moisture and photochemical cured polymerization. Magnetic self-assembly, carried out in biofriendly aqueous buffers, provides weak bonding not suitable for long term applications. Moisture cured bonding of covalently modified SU-8 substrates, based on silanol condensation, resulted in weak and inconsistent bonding. Photocured bonding using a medical grade adhesive and of acrylate modified substrates provided stable bonding. Of the methods evaluated, photo-cured adhesion provided the strongest and most stable adhesion. PMID:21970658

  16. Preparation and application of microcapsule-encapsulated color electrophortic fluid in Isopar M system for electrophoretic display

    NASA Astrophysics Data System (ADS)

    Sun, Cui; Feng, Ya-Qing; Zhang, Bao; Li, Xiang-Gao; Shao, Ji-Zhou; Han, Jing-Jing; Chen, Xu

    2013-05-01

    The use of Isopar M as a liquid suspending fluid for electrophoretic display was studied. The dispersion stability and chargeability of pigments suspended in Isopar M were investigated. Polyisobutylene monosuccinimide (T-151) as the charge control additive in Isopar M electrophoretic fluid can provide a good electrophoretic mobility to the particles. The wall materials of a series of blue-white, red-white and yellow-white dual-particle microcapsules were prepared by in situ polymerization of urea and formaldehyde. The mass ratio of wall/core material was a key factor in influencing the yield of microcapsules. The concentration of resorcinol has an impact on the surface morphology and mechanical strength of microcapsule wall. Microcapsules' surface morphologies were characterized by optical microscopy and scanning electron microscopy. The performance of the microcapsules with different binder materials and adhesive layers were investigated. Contrast ratio of microcapsules display device were tested every 10 days for a period of 90 days. The compatibility of Isopar M with both the electrophoretic particles and bounding capsule was studied.

  17. Microcapsules and Methods for Making

    NASA Technical Reports Server (NTRS)

    Morrison, Dennis R. (Inventor); Mosier, Benjamin (Inventor)

    1998-01-01

    Methods of forming multi-lamellar microcapsules having alternating layers of hydrophilic and hydrophobic immiscible liquid phases have been developed using different polymer/solvent systems. The methods use liquid-liquid diffusion and simultaneous lateral phase separation, controlled by proper timed-sequence exposures of immiscible phases and low shear mixing, to form narrow size distributions of spherical, multilamellar microcapsules. The use of special formulations of solubilized drugs, surfactants, and polymeric co-surfactants in aqueous vehicles which are dispersed in hydrocarbon solvents containing small quantities of oil, low molecular weight co-surfactants and glycerides that are aqueous insoluble enables the formation of unique microcapsules which can carry large amounts of pharmaceuticals in both aqueous and non-aqueous solvent compartments. The liquid microcapsules are quickly formed in a single step and can include a polymeric outer 'skin' which protects the microcapsules during physical manipulation or exposure to high shear forces. Water-in-oil and oil-in-water microcapsules have been formed both in 1 x g and in microgravity, which contain several types of drugs co-encapsulated within different fluid compartments inside the same microcapsule. Large, spherical multi-lamellar microcapsules have been formed including a cytotoxic drug co-encapsulated with a radiocontrast medium which has advantages for chemoembolization of vascular tumors. In certain cases, crystals of the drug form inside the microcapsules providing zero-order and first order, sustained drug release kinetics.

  18. Enzyme immobilisation in permselective microcapsules.

    PubMed

    Pachariyanon, Pavadee; Barth, Ekkehard; Agar, David W

    2011-01-01

    The objective of this investigation was to study the permselective behaviour of calcium alginate membranes, including the modifying effects of silica additives, which were subsequently used as microcapsule shells. Diffusion experiments and HPLC were carried out to ascertain the size-exclusion property of the membranes for a mixed molecular-weight dextran solution. Hollow microcapsules containing the enzyme dextranase were prepared using double concentric nozzles and the encapsulation performance was evaluated based on an analysis of the enzyme reactivity and stability. To improve mass transport within the microcapsules, magnetic nanoparticles were introduced into the liquid core and agitated using an alternating external magnetic field. The modified membranes exhibited better size-exclusion behaviour than the unmodified membranes. The magnetic nanoparticles slightly improved mass transport inside the microcapsule. The encapsulated enzyme yielded nearly 80% of the free enzyme activity and retained about 80% of the initial catalytic activity even after being used for eight reaction cycles. PMID:21736522

  19. Highly stable microwave susceptible agents via encapsulation of Ti-mineral superfine powders in urea-formaldehyde resin microcapsules for tumor hyperthermia therapy.

    PubMed

    Long, Dan; Mao, Jingsong; Liu, Tianlong; Fu, Changhui; Tan, Longfei; Ren, Xiangling; Shi, Haitang; Su, Hongying; Ren, Jun; Meng, Xianwei

    2016-06-01

    In this study, Ti-mineral superfine powders (Ti-MSP) encapsulated in urea-formaldehyde resin microcapsules (Ti-MSP@UF-MC) were successfully prepared via a one-step microemulsion method for the first time. Because of the strong confinement effects, the Ti-MSP@UF-MC possessed perfect microwave heating effects. The temperature was 9.3 °C higher than that of the saline solution, superior to UF-MC (no significant microwave heating effect, 0 °C) and Ti-MSP (5.1 °C). The Ti-MSP@UF-MC showed low toxicity and good biocompatibility via a series of studies, including a hemolysis study and the MTT assay in vitro and in vivo. When the concentration was below 1000 μg mL(-1), the hemolysis rate was lower than 5% (hemolysis study). When the concentration was below 400 μg mL(-1), the cell activity was higher than 80% (MTT assay). Moreover, the Ti-MSP@UF-MC exhibited an ideal CT imaging effect in vivo owing to the large molecular weight of Ti-MSP. The Ti-MSP@UF-MC showed a favorable microwave therapy effect in vivo. Using mice bearing H22 tumor cells as an animal model, the tumor suppression rate could reach 100%. PMID:27174624

  20. Highly stable microwave susceptible agents via encapsulation of Ti-mineral superfine powders in urea-formaldehyde resin microcapsules for tumor hyperthermia therapy

    NASA Astrophysics Data System (ADS)

    Long, Dan; Mao, Jingsong; Liu, Tianlong; Fu, Changhui; Tan, Longfei; Ren, Xiangling; Shi, Haitang; Su, Hongying; Ren, Jun; Meng, Xianwei

    2016-05-01

    In this study, Ti-mineral superfine powders (Ti-MSP) encapsulated in urea-formaldehyde resin microcapsules (Ti-MSP@UF-MC) were successfully prepared via a one-step microemulsion method for the first time. Because of the strong confinement effects, the Ti-MSP@UF-MC possessed perfect microwave heating effects. The temperature was 9.3 °C higher than that of the saline solution, superior to UF-MC (no significant microwave heating effect, 0 °C) and Ti-MSP (5.1 °C). The Ti-MSP@UF-MC showed low toxicity and good biocompatibility via a series of studies, including a hemolysis study and the MTT assay in vitro and in vivo. When the concentration was below 1000 μg mL-1, the hemolysis rate was lower than 5% (hemolysis study). When the concentration was below 400 μg mL-1, the cell activity was higher than 80% (MTT assay). Moreover, the Ti-MSP@UF-MC exhibited an ideal CT imaging effect in vivo owing to the large molecular weight of Ti-MSP. The Ti-MSP@UF-MC showed a favorable microwave therapy effect in vivo. Using mice bearing H22 tumor cells as an animal model, the tumor suppression rate could reach 100%.

  1. Hydrophobic-Core Microcapsules and Their Formation

    NASA Technical Reports Server (NTRS)

    Calle, Luz M. (Inventor); Li, Wenyan (Inventor); Buhrow, Jerry W. (Inventor); Jolley, Scott T. (Inventor)

    2016-01-01

    Hydrophobic-core microcapsules and methods of their formation are provided. A hydrophobic-core microcapsule may include a shell that encapsulates a hydrophobic substance with a core substance, such as dye, corrosion indicator, corrosion inhibitor, and/or healing agent, dissolved or dispersed therein. The hydrophobic-core microcapsules may be formed from an emulsion having hydrophobic-phase droplets, e.g., containing the core substance and shell-forming compound, dispersed in a hydrophilic phase. The shells of the microcapsules may be capable of being broken down in response to being contacted by an alkali, e.g., produced during corrosion, contacting the shell.

  2. Hydrophilic-Core Microcapsules and Their Formation

    NASA Technical Reports Server (NTRS)

    Calle, Luz M. (Inventor); Li, Wenyan (Inventor); Buhrow, Jerry W. (Inventor); Jolley, Scott T. (Inventor)

    2016-01-01

    Hydrophilic-core microcapsules and methods of their formation are provided. A hydrophilic-core microcapsule may include a shell that encapsulates water with the core substance dissolved or dispersed therein. The hydrophilic-core microcapsules may be formed from an emulsion having hydrophilic-phase droplets dispersed in a hydrophobic phase, with shell-forming compound contained in the hydrophilic phase or the hydrophobic phase and the core substance contained in the hydrophilic phase. The shells of the microcapsules may be capable of being broken down in response to being contacted by an alkali, e.g., produced during corrosion, contacting the shell.

  3. Encapsulating Ionic Liquid and Fe₃O₄ Nanoparticles in Gelatin Microcapsules as Microwave Susceptible Agent for MR Imaging-guided Tumor Thermotherapy.

    PubMed

    Du, Qijun; Ma, Tengchuang; Fu, Changhui; Liu, Tianlong; Huang, Zhongbing; Ren, Jun; Shao, Haibo; Xu, Ke; Tang, Fangqiong; Meng, Xianwei

    2015-06-24

    The combination of therapies and monitoring the treatment process has become a new concept in cancer therapy. Herein, gelatin-based microcapsules have been first reported to be used as microwave (MW) susceptible agent and magnetic resonance (MR) imaging contrast agent for cancer MW thermotherapy. Using the simple coacervation methods, ionic liquid (IL) and Fe3O4 nanoparticles (NPs) were wrapped in microcapsules, and these microcapsules showed good heating efficacy in vitro under MW irradiation. The results of cell tests indicated that gelatin/IL@Fe3O4 microcapsules possessed excellent compatibility in physiological environments, and they could effectively kill cancer cells with exposure to MW. The ICR mice bearing H22 tumors treated with gelatin/IL@Fe3O4 microcapsules were obtained an outstanding MW thermotherapy efficacy with 100% tumor elimination under ultralow density irradiation (1.8 W/cm(2), 450 MHz). In addition, the applicability of the microcapsules as an efficient contrast agent for MR imaging in vivo was evident. Therefore, these multifunctional microcapsules have a great potential for MR imaging-guided MW thermotherapy. PMID:26031508

  4. Formulation and Characterization of Rifampicin Microcapsules

    PubMed Central

    Sarfaraz, MD.; Hiremath, D.; Chowdary, K. P. R.

    2010-01-01

    Rifampicin biodegradable microcapsules were prepared by feasible emulsification-ionic gelation method for a novel controlled release product. Sodium alginate and Carbopol 974P were used as coating polymers in different ratios 1:1, 1:2, 1:3 and 1:4 to obtain elegant microcapsules. The formulations were characterized for encapsulation efficiency, drug loading, sieve analysis, scanning electron microscopy and in vitro release studies. The microcapsules were discrete, large, almost spherical and free flowing with encapsulation efficiency in the range of 75% to 89%, drug loading 75% to 86% and size 440 μm to 500 μm. Rifampicin release from these microcapsules was slow and extended over longer periods of time depending on the polymer coat. Drug release was diffusion controlled and followed first order kinetics. The formulation MC1 with a coating ratio of 1:1 (Sodium alginate: Carbopol 974P) was found to be suitable for oral controlled release. PMID:20582197

  5. Microcapsules and Methods for Making

    NASA Technical Reports Server (NTRS)

    Morrison, Dennis R. (Inventor); Mosier, Benjamin (Inventor)

    1994-01-01

    This invention relates to methods for forming multi-lamellar microcapsules of both hydrophilic and hydrophobic immiscible liquid phases using several polymer/solvent systems. Liquid-Liquid diffusion and spontaneous emulsification are controlled by properly timed sequence exposures of immiscible phases in aqueous vehicles dispersed in hydrocarbon solvents containing small quantities of oil, co-surfactants, and glycerides. Water-in-oil and oil-in-water microcapsules are formed containing selected combinations of several types of drugs, co-encapsulated within fluid compartments inside the microcapsule. Commercial applications of the process and the resultant product relate to drug therapy for treating medical conditions such as cancer, circulatory conditions, and other conditions in which pharmaceuticals are advantageously targeted to specific organs, or delivered in combination with other pharmaceuticals. Small microcapsules may be delivered intravenously to diseased organs or clotted vessels. The use of multiple drugs within the same microcapsule structure provides advantages for applications such as chemoembolization treatments and may be used to deliver both chemotherapeutic drugs, against tumor cells, and an immuno-adjuvant or immunological stimulant to enhance the patient's immune response. Active forms of urokinase and other enzymes may be delivered without dilution to the local site of an embolism for dissolving the embolism. Thus, the invention has several potentially valuable commercial applications related to pharmaceutical and medical applications.

  6. Enhanced oxidative stability of fish oil by encapsulating in culled banana resistant starch-soy protein isolate based microcapsules in functional bakery products.

    PubMed

    Nasrin, Taslima Ayesha Aktar; Anal, Anil Kumar

    2015-08-01

    Oil in water emulsions were produced by the mixture of culled banana resistant starch (CBRS) & soy protein isolate (SPI), mixture of Hylon VII & SPI and SPI with 7.5 and 5 % (w/w) Menhaden fish oil. The emulsions were further freeze- dried obtaining 33 and 50 % oil load microcapsules. The range of particles diameter was 4.11 to 7.25 μm and viscosity was 34.6 to 146.48 cP of the emulsions. Compressibility index (CI), Hasner ratio (HR) and angle of repose (AR) was significantly (p < 0.01) lower of the microcapsules made with starch and protein (CBRS & SPI and Hylon VII & SPI) than that made with protein (SPI) only. Microcapsules composed of CBRS & SPI with 33 % oil load had maximum microencapsulation efficiency (82.49 %) and highest oxidative stability. Muffin made with emulsions containing mixture of CBRS & SPI exhibited less fishy flavour than that containing mixture of Hylon VII & SPI. PMID:26243933

  7. Microfluidic production of multiple emulsions and functional microcapsules.

    PubMed

    Lee, Tae Yong; Choi, Tae Min; Shim, Tae Soup; Frijns, Raoul A M; Kim, Shin-Hyun

    2016-09-21

    Recent advances in microfluidics have enabled the controlled production of multiple-emulsion drops with onion-like topology. The multiple-emulsion drops possess an intrinsic core-shell geometry, which makes them useful as templates to create microcapsules with a solid membrane. High flexibility in the selection of materials and hierarchical order, achieved by microfluidic technologies, has provided versatility in the membrane properties and microcapsule functions. The microcapsules are now designed not just for storage and release of encapsulants but for sensing microenvironments, developing structural colours, and many other uses. This article reviews the current state of the art in the microfluidic-based production of multiple-emulsion drops and functional microcapsules. The three main sections of this paper discuss distinct microfluidic techniques developed for the generation of multiple emulsions, four representative methods used for solid membrane formation, and various applications of functional microcapsules. Finally, we outline the current limitations and future perspectives of microfluidics and microcapsules. PMID:27470590

  8. Comparison of Calcium and Barium Microcapsules as Scaffolds in the Development of Artificial Dermal Papillae.

    PubMed

    Liu, Yang; Lin, Changmin; Zeng, Yang; Li, Haihong; Cai, Bozhi; Huang, Keng; Yuan, Yanping; Li, Yu

    2016-01-01

    This study aimed to develop and evaluate barium and calcium microcapsules as candidates for scaffolding in artificial dermal papilla. Dermal papilla cells (DPCs) were isolated and cultured by one-step collagenase treatment. The DPC-Ba and DPC-Ca microcapsules were prepared by using a specially designed, high-voltage, electric-field droplet generator. Selected microcapsules were assessed for long-term inductive properties with xenotransplantation into Sprague-Dawley rat ears. Both barium and calcium microcapsules maintained xenogenic dermal papilla cells in an immunoisolated environment and induced the formation of hair follicle structures. Calcium microcapsules showed better biocompatibility, permeability, and cell viability in comparison with barium microcapsules. Before 18 weeks, calcium microcapsules gathered together, with no substantial immune response. After 32 weeks, some microcapsules were near inflammatory cells and wrapped with fiber. A few large hair follicles were found. Control samples showed no marked changes at the implantation site. Barium microcapsules were superior to calcium microcapsules in structural and mechanical stability. The cells encapsulated in hydrogel barium microcapsules exhibited higher short-term viability. This study established a model to culture DPCs in 3D culture conditions. Barium microcapsules may be useful in short-term transplantation study. Calcium microcapsules may provide an effective scaffold for the development of artificial dermal papilla. PMID:27123456

  9. Comparison of Calcium and Barium Microcapsules as Scaffolds in the Development of Artificial Dermal Papillae

    PubMed Central

    Liu, Yang; Lin, Changmin; Zeng, Yang; Li, Haihong; Cai, Bozhi; Huang, Keng; Yuan, Yanping; Li, Yu

    2016-01-01

    This study aimed to develop and evaluate barium and calcium microcapsules as candidates for scaffolding in artificial dermal papilla. Dermal papilla cells (DPCs) were isolated and cultured by one-step collagenase treatment. The DPC-Ba and DPC-Ca microcapsules were prepared by using a specially designed, high-voltage, electric-field droplet generator. Selected microcapsules were assessed for long-term inductive properties with xenotransplantation into Sprague-Dawley rat ears. Both barium and calcium microcapsules maintained xenogenic dermal papilla cells in an immunoisolated environment and induced the formation of hair follicle structures. Calcium microcapsules showed better biocompatibility, permeability, and cell viability in comparison with barium microcapsules. Before 18 weeks, calcium microcapsules gathered together, with no substantial immune response. After 32 weeks, some microcapsules were near inflammatory cells and wrapped with fiber. A few large hair follicles were found. Control samples showed no marked changes at the implantation site. Barium microcapsules were superior to calcium microcapsules in structural and mechanical stability. The cells encapsulated in hydrogel barium microcapsules exhibited higher short-term viability. This study established a model to culture DPCs in 3D culture conditions. Barium microcapsules may be useful in short-term transplantation study. Calcium microcapsules may provide an effective scaffold for the development of artificial dermal papilla. PMID:27123456

  10. CHO immobilization in alginate/poly-L: -lysine microcapsules: an understanding of potential and limitations.

    PubMed

    Breguet, Véronique; Gugerli, Raphaël; von Stockar, Urs; Marison, Ian William

    2007-04-01

    Microencapsulation offers a unique potential for high cell density, high productivity mammalian cell cultures. However, for successful exploitation there is the need for microcapsules of defined size, properties and mechanical stability. Four types of alginate/poly-L: -Lysine microcapsules, containing recombinant CHO cells, have been investigated: (a) 800 mum liquid core microcapsules, (b) 500 mum liquid core microcapsules, (c) 880 mum liquid core microcapsules with a double PLL membrane and (d) 740 mum semi-liquid core microcapsules. With encapsulated cells a reduced growth rate was observed, however this was accompanied by a 2-3 fold higher specific production rate of the recombinant protein. Interestingly, the maximal intracapsular cell concentration was only 8.7 x 10(7) cell mL(-1), corresponding to a colonization of 20% of the microcapsule volume. The low level of colonization is unlikely to be due to diffusional limitations since reduction of microcapsule size had no effect. Measurement of cell leaching and mechanical properties showed that liquid core microcapsules are not suitable for continuous long-term cultures (>1 month). By contrast semi-liquid core microcapsules were stable over long periods with a constant level of cell colonization (varphi = 3%). This indicates that the alginate in the core plays a predominant role in determining the level of microcapsule colonization. This was confirmed by experiments showing reduced growth rates of batch suspension cultures of CHO cells in medium containing dissolved alginate. Removal of this alginate would therefore be expected to increase microcapsule colonization. PMID:19003193

  11. Controlled-Release Microcapsules for Smart Coatings for Corrosion Applications

    NASA Technical Reports Server (NTRS)

    2008-01-01

    Corrosion is a serious problem that has enormous costs and serious safety implications. Localized corrosion, such as pitting, is very dangerous and can cause catastrophic failures. The NASA Corrosion Technology Laboratory at Kennedy Space Center is developing a smart coating based on pH-sensitive microcapsules for corrosion applications. These versatile microcapsules are designed to be incorporated into a smart coating and deliver their core content when corrosion starts. Corrosion indication was the first function incorporated into the microcapsules. Current efforts are focused on incorporating the corrosion inhibition function through the encapsulation of corrosion inhibitors into water core and oil core microcapsules. Scanning electron microscopy (SEM) images of encapsulated corrosion inhibitors are shown.

  12. Controlled release of vancomycin from biodegradable microcapsules.

    PubMed

    Ozalp, Y; Ozdemir, N; Kocagöz, S; Hasirci, V

    2001-01-01

    Poly D,L-lactic acid (PLA) and its copolymers with glycolide PLGA 90:10 and 70:30 were polymerized under various conditions to yield polymers in the molecular weight range 12000-40000 daltons, as determined by gel permeation chromatography. Vancomycin hydrochloride was the hydrophilic drug of choice for the treatment of methicillin resistant Staphyloccoccal infections. It was microencapsulated in the synthesized polymers using water-oil-water (w/o/w) double emulsion and solvent evaporation. The influence of microcapsule preparation medium on product properties was investigated. An increase in polymer-to-drug ratio from 1:1 to 3:1 caused an increase in the encapsulation efficiency (i.e. from 44-97% with PLGA). An increase in the emulsifier (PVA) molecular weight from 14-72 kD caused an increase in encapsulation efficiency and microcapsule size. The in vitro release of vancomycin from microcapsules in phosphate buffer saline (pH 7.4) was found to be dependent on molecular weight and copolymer type. The kinetic behaviour was controlled by both diffusion and degradation. Sterilization with 60Co (2.5 Mrad) also affected the degradation rate and release profiles. Degradation of microcapsules could be seen by scanning electron microscopy, by the increase in the release rate from PLA and by the decrease in the Tg values of microcapsules. In vitro bactericidal effects of the microcapsule formulations on S. aureus were determined with a special diffusion cell after the preparations had been sterilized, and were found to have bactericidal effects lasting for 4 days. PMID:11201344

  13. One-Step Generation of Multifunctional Polyelectrolyte Microcapsules via Nanoscale Interfacial Complexation in Emulsion (NICE).

    PubMed

    Kim, Miju; Yeo, Seon Ju; Highley, Christopher B; Burdick, Jason A; Yoo, Pil J; Doh, Junsang; Lee, Daeyeon

    2015-08-25

    Polyelectrolyte microcapsules represent versatile stimuli-responsive structures that enable the encapsulation, protection, and release of active agents. Their conventional preparation methods, however, tend to be time-consuming, yield low encapsulation efficiency, and seldom allow for the dual incorporation of hydrophilic and hydrophobic materials, limiting their widespread utilization. In this work, we present a method to fabricate stimuli-responsive polyelectrolyte microcapsules in one step based on nanoscale interfacial complexation in emulsions (NICE) followed by spontaneous droplet hatching. NICE microcapsules can incorporate both hydrophilic and hydrophobic materials and also can be induced to trigger the release of encapsulated materials by changes in the solution pH or ionic strength. We also show that NICE microcapsules can be functionalized with nanomaterials to exhibit useful functionality, such as response to a magnetic field and disassembly in response to light. NICE represents a potentially transformative method to prepare multifunctional nanoengineered polyelectrolyte microcapsules for various applications such as drug delivery and cell mimicry. PMID:26172934

  14. Core-Shell Chitosan Microcapsules for Programmed Sequential Drug Release.

    PubMed

    Yang, Xiu-Lan; Ju, Xiao-Jie; Mu, Xiao-Ting; Wang, Wei; Xie, Rui; Liu, Zhuang; Chu, Liang-Yin

    2016-04-27

    A novel type of core-shell chitosan microcapsule with programmed sequential drug release is developed by the microfluidic technique for acute gastrosis therapy. The microcapsule is composed of a cross-linked chitosan hydrogel shell and an oily core containing both free drug molecules and drug-loaded poly(lactic-co-glycolic acid) (PLGA) nanoparticles. Before exposure to acid stimulus, the resultant microcapsules can keep their structural integrity without leakage of the encapsulated substances. Upon acid-triggering, the microcapsules first achieve burst release due to the acid-induced decomposition of the chitosan shell. The encapsulated free drug molecules and drug-loaded PLGA nanoparticles are rapidly released within 60 s. Next, the drugs loaded in the PLGA nanoparticles are slowly released for several days to achieve sustained release based on the synergistic effect of drug diffusion and PLGA degradation. Such core-shell chitosan microcapsules with programmed sequential drug release are promising for rational drug delivery and controlled-release for the treatment of acute gastritis. In addition, the microcapsule systems with programmed sequential release provide more versatility for controlled release in biomedical applications. PMID:27052812

  15. Synthesis of Bioactive Microcapsules Using a Microfluidic Device

    PubMed Central

    Kim, Byeong Il; Jeong, Soon Woo; Lee, Kyoung G.; Park, Tae Jung; Park, Jung Youn; Song, Jae Jun; Lee, Seok Jae; Lee, Chang-Soo

    2012-01-01

    Bioactive microcapsules containing Bacillus thuringiensis (BT) spores were generated by a combination of a hydro gel, microfluidic device and chemical polymerization method. As a proof-of-principle, we used BT spores displaying enhanced green fluorescent protein (EGFP) on the spore surface to spatially direct the EGFP-presenting spores within microcapsules. BT spore-encapsulated microdroplets of uniform size and shape are prepared through a flow-focusing method in a microfluidic device and converted into microcapsules through hydrogel polymerization. The size of microdroplets can be controlled by changing both the dispersion and continuous flow rate. Poly(N-isoproplyacrylamide) (PNIPAM), known as a hydrogel material, was employed as a biocompatible material for the encapsulation of BT spores and long-term storage and outstanding stability. Due to these unique properties of PNIPAM, the nutrients from Luria-Bertani complex medium diffused into the microcapsules and the microencapsulated spores germinated into vegetative cells under adequate environmental conditions. These results suggest that there is no limitation of transferring low-molecular-weight-substrates through the PNIPAM structures, and the viability of microencapsulated spores was confirmed by the culture of vegetative cells after the germinations. This microfluidic-based microencapsulation methodology provides a unique way of synthesizing bioactive microcapsules in a one-step process. This microfluidic-based strategy would be potentially suitable to produce microcapsules of various microbial spores for on-site biosensor analysis. PMID:23112592

  16. Image density property of optical information recording microcapsule material

    NASA Astrophysics Data System (ADS)

    Lai, Weidong; Li, Xiaowei; Li, Xinzheng; Fu, Guangsheng

    2009-05-01

    The microcapsules can act as novel optical functional material in which the optical recording substance such as color-forming substance, photoinitiator and prepolymer are encapsulated. In this paper, the microcapsules with average particle diameter of 300nm are prepared with interfacial polymerization method. The optical responding character of the microcapsule is analyzed based on IR spectra and image density technique. Results show that the microcapsule material encapsulated prepolymer TMPTA and photoinitiator Irgacure-ITX, TPO has thermal phase-change at 140°C, at which the penetrability of the microcapsule has the highest efficiency. With the increase of exposure time, the reduction in absorption intensities of the prepolymer TMPTA are observed at 1635cm-1 of C=C stretching and 898cm-1 of C-H stretching on the C=C molecular bond. Such a result can be ascribed to the double bond cleavage process of the prepolymer TMPTA is initiated by the optical-exposed photoinitiator, and superpolymer network is formed. The image density contrast between the unexposed and exposed microcapsule is enhanced with exposure time increased.

  17. Fabrication of hollow melamine-formaldehyde microcapsules from microbubble templates.

    PubMed

    Daiguji, Hirofumi; Makuta, Toshinori; Kinoshita, Hiroki; Oyabu, Takayuki; Takemura, Fumio

    2007-08-01

    A fabrication method for hollow melamine-formaldehyde microcapsules from microbubble templates is presented. This method is based on the direct encapsulation of microbubbles, and thus does not require a liquid- or solid-core decomposition process. This study determined the conditions for controlling the surface morphology, shell thickness, and diameter distribution of hollow microcapsules. Results showed that the surface morphology of these hollow microcapsules depended on the reaction time, glycine concentration (pH of aqueous continuous phase) and pre-polymer concentration. The capsule shell thickness could be controlled by adjusting the concentration of aniline that had adsorbed on the microbubble surface and reacted with pre-polymer. The capsule diameter depended on the dissolution rate of gases, and the diameter of the hollow microcapsules fabricated from air microbubble templates ranged from 5 to 200 microm. PMID:17602584

  18. Microencapsulation of curcumin in PLGA microcapsules by coaxial flow focusing

    NASA Astrophysics Data System (ADS)

    Lei, Fan; Si, Ting; Luo, Xisheng; Xu, Ronald X.

    2014-03-01

    Curcumin-loaded PLGA microcapsules are fabricated by a liquid-driving coaxial flow focusing device. In the process, a stable coaxial cone-jet configuration is formed under the action of a coflowing liquid stream and the coaxial liquid jet eventually breaks up into microcapsules because of flow instability. This process can be well controlled by adjusting the flow rates of three phases including the driving PVA water solution, the outer PLGA ethyl acetate solution and the inner curcumin propylene glycol solution. Confocal and SEM imaging methods clearly indicate the core-shell structure of the resultant microcapsules. The encapsulation rate of curcumin in PLGA is measured to be more than 70%, which is much higher than the tranditional methods such as emulsion. The size distribution of resultant microcapsules under different conditions is presented and compared. An in vitro release simulation platform is further developed to verify the feasibility and reliability of the method.

  19. Synthesis of Elongated Microcapsules

    NASA Technical Reports Server (NTRS)

    Li, Wenyan; Buhrow, Jerry; Calle, Luz M.

    2011-01-01

    One of the factors that influence the effectiveness of self-healing in functional materials is the amount of liquid healing agents that can be delivered to the damaged area. The use of hollow tubes or fibers and the more sophisticated micro-vascular networks has been proposed as a way to increase the amount of healing agents that can be released when damage is inflicted. Although these systems might be effective in some specific applications, they are not practical for coatings applications. One possible practical way to increase the healing efficiency is to use microcapsules with high-aspect-ratios, or elongated microcapsules. It is understood that elongated microcapsules will be more efficient because they can release more healing agent than a spherical microcapsule when a crack is initiated in the coating. Although the potential advantage of using elongated microcapsules for self healing applications is clear, it is very difficult to make elongated microcapsules from an emulsion system because spherical microcapsules are normally formed due to the interfacial tension between the dispersed phase and the continuous phase. This paper describes the two methods that have been developed by the authors to synthesize elongated microcapsules. The first method involves the use of an emulsion with intermediate stability and the second involves the application of mechanical shear conditions to the emulsion.

  20. Surface modified alginate microcapsules for 3D cell culture

    NASA Astrophysics Data System (ADS)

    Chen, Yi-Wen; Kuo, Chiung Wen; Chueh, Di-Yen; Chen, Peilin

    2016-06-01

    Culture as three dimensional cell aggregates or spheroids can offer an ideal platform for tissue engineering applications and for pharmaceutical screening. Such 3D culture models, however, may suffer from the problems such as immune response and ineffective and cumbersome culture. This paper describes a simple method for producing microcapsules with alginate cores and a thin shell of poly(L-lysine)-graft-poly(ethylene glycol) (PLL-g-PEG) to encapsulate mouse induced pluripotent stem (miPS) cells, generating a non-fouling surface as an effective immunoisolation barrier. We demonstrated the trapping of the alginate microcapsules in a microwell array for the continuous observation and culture of a large number of encapsulated miPS cells in parallel. miPS cells cultured in the microcapsules survived well and proliferated to form a single cell aggregate. Droplet formation of monodisperse microcapsules with controlled size combined with flow cytometry provided an efficient way to quantitatively analyze the growth of encapsulated cells in a high-throughput manner. The simple and cost-effective coating technique employed to produce the core-shell microcapsules could be used in the emerging field of cell therapy. The microwell array would provide a convenient, user friendly and high-throughput platform for long-term cell culture and monitoring.

  1. Construction of a controlled-release delivery system for pesticides using biodegradable PLA-based microcapsules.

    PubMed

    Liu, Baoxia; Wang, Yan; Yang, Fei; Wang, Xing; Shen, Hong; Cui, Haixin; Wu, Decheng

    2016-08-01

    Conventional pesticides usually need to be used in more than recommended dosages due to their loss and degradation, which results in a large waste of resources and serious environmental pollution. Encapsulation of pesticides in biodegradable carriers is a feasible approach to develop environment-friendly and efficient controlled-release delivery system. In this work, we fabricated three kinds of polylactic acid (PLA) carriers including microspheres, microcapsules, and porous microcapsules for controlled delivery of Lambda-Cyhalothrin (LC) via premix membrane emulsification (PME). The microcapsule delivery system had better water dispersion than the other two systems. Various microcapsules with a high LC contents as much as 40% and tunable sizes from 0.68 to 4.6μm were constructed by manipulating the process parameters. Compared with LC technical and commercial microcapsule formulation, the microcapsule systems showed a significantly sustained release of LC for a longer period. The LC release triggered by LC diffusion and matrix degradation could be optimally regulated by tuning LC contents and particle sizes of the microcapsules. This multi-regulated release capability is of great significance to achieve the precisely controlled release of pesticides. A preliminary bioassay against plutella xylostella revealed that 0.68μm LC-loaded microcapsules with good UV and thermal stability exhibited an activity similar to a commercial microcapsule formulation. These results demonstrated such an aqueous microcapsule delivery system had a great potential to be further explored for developing an effective and environmentally friendly pesticide-release formulation. PMID:27062215

  2. The design of wrinkled microcapsules for enhancement of release rate.

    PubMed

    Ina, Maria; Zhushma, Aleksandr P; Lebedeva, Natalia V; Vatankhah-Varnoosfaderani, Mohammad; Olson, Sean D; Sheiko, Sergei S

    2016-09-15

    Thermally expandable microcapsules (TEMs) with wrinkled shells are prepared by one-step suspension polymerization, allowing for encapsulation and controlled release of cargos. Wrinkling results from concurrent crosslinking of shell copolymers and vaporization of volatile reagents along with density increase upon polymerization. Through control of the vapor pressure of the reagents and systematic variation of the suspension composition, microcapsules with different degrees of wrinkling are prepared, ranging from locally dimpled to highly crumpled morphologies. The corresponding increase of the surface-to-volume ratio results in increasing release rate of encapsulated oil red dye as a model cargo. As such, in addition to shell thickness and radius, the wrinkleness provides an effective control parameter for adjusting the release rate. The wrinkled microcapsules with a large surface-to-volume ratio may find applications in drug delivery, chemicals scavenging, and self-healing materials. PMID:27309950

  3. Microcapsules for Enhanced Cargo Retention and Diversity.

    PubMed

    Zieringer, Maximilian A; Carroll, Nick J; Abbaspourrad, Alireza; Koehler, Stephan A; Weitz, David A

    2015-06-24

    Prevention of undesired leakage of encapsulated materials prior to triggered release presents a technological challenge for the practical application of microcapsule technologies in agriculture, drug delivery, and cosmetics. A microfluidic approach is reported to fabricate perfluoropolyether (PFPE)-based microcapsules with a high core-shell ratio that show enhanced retention of encapsulated actives. For the PFPE capsules, less than 2% leakage of encapsulated model compounds, including Allura Red and CaCl2 , over a four week trial period is observed. In addition, PFPE capsules allow cargo diversity by the fabrication of capsules with either a water-in-oil emulsion or an organic solvent as core. Capsules with a toluene-based core begin a sustained release of hydrophobic model encapsulants immediately upon immersion in an organic continuous phase. The major contribution on the release kinetics stems from the toluene in the core. Furthermore, degradable silica particles are incorporated to confer porosity and functionality to the otherwise chemically inert PFPE-based polymer shell. These results demonstrate the capability of PFPE capsules with large core-shell ratios to retain diverse sets of cargo for extended periods and make them valuable for controlled release applications that require a low residual footprint of the shell material. PMID:25693141

  4. Biodegradable polymer microcapsules fabrication through a template-free approach.

    PubMed

    Yu, Xi; Zhao, Ziliang; Nie, Wei; Deng, Renhua; Liu, Shanqin; Liang, Ruijing; Zhu, Jintao; Ji, Xiangling

    2011-08-16

    A detailed study on the direct synthesis of biocompatible polyesters (e.g., PLA, PLGA or PCL) microcapsules and multifunctional microcapsules, which does not require any template and core removal, is presented. The technique is based on the modified self-emulsification process within the emulsion droplets by simply adding sodium dioctyl sulfosuccinate (Aerosol OT or AOT) as a cosurfactant to the initial polymer solution, followed by double emulsion formation due to the coalescence of the internal water droplets. Microcapsules with tunable sizes (ranging from hundreds of nanometers to tens of micrometers) and morphologies were then obtained through solidification of droplet shell of the double emulsion via solvent removal. In this report, we have systematically investigated the effect of experimental parameters, such as polymer and AOT concentration, polymer molecular weight on the double emulsion formation process, and the final morphologies of the microcapsules. We demonstrate that the capsules can encapsulate either hydrophobic or hydrophilic dyes during solvent evaporation. Dye-release studies show a correlation between shell thickness, capsules size, and diffusive release rate, providing insights into the shell formation and shell thickness processing. Moreover, hydrophobic nanoparticles, such as oleic-acid coated Fe(3)O(4) nanoparticles and quantum dots, can also be incorporated into the walls of the microcapsules. Such functional microcapsules might find applications in the fields of controlled release, bioimaging, diagnostics, and targeting. PMID:21766809

  5. Microcapsule and methods of making and using microcapsules

    SciTech Connect

    Okawa, David C.; Pastine, Stefan J.; Zettl, Alexander K.; Frechet, Jean M.J.

    2014-09-02

    An embodiment of a microcapsule includes a shell surrounding a space, a liquid within the shell, and a light absorbing material within the liquid. An embodiment of a method of making microcapsules includes forming a mixture of a light absorbing material and an organic solution. An emulsion of the mixture and an aqueous solution is then formed. A polymerization agent is added to the emulsion, which causes microcapsules to be formed. Each microcapsule includes a shell surrounding a space, a liquid within the shell, and light absorbing material within the liquid. An embodiment of a method of using microcapsules includes providing phototriggerable microcapsules within a bulk material. Each of the phototriggerable microcapsules includes a shell surrounding a space, a chemically reactive material within the shell, and a light absorbing material within the shell. At least some of the phototriggerable microcapsules are exposed to light, which causes the chemically reactive material to release from the shell and to come into contact with bulk material.

  6. CHO immobilization in alginate/poly-l-lysine microcapsules: an understanding of potential and limitations

    PubMed Central

    Breguet, Véronique; Gugerli, Raphaël; von Stockar, Urs

    2007-01-01

    Microencapsulation offers a unique potential for high cell density, high productivity mammalian cell cultures. However, for successful exploitation there is the need for microcapsules of defined size, properties and mechanical stability. Four types of alginate/poly-l-Lysine microcapsules, containing recombinant CHO cells, have been investigated: (a) 800 μm liquid core microcapsules, (b) 500 μm liquid core microcapsules, (c) 880 μm liquid core microcapsules with a double PLL membrane and (d) 740 μm semi-liquid core microcapsules. With encapsulated cells a reduced growth rate was observed, however this was accompanied by a 2–3 fold higher specific production rate of the recombinant protein. Interestingly, the maximal intracapsular cell concentration was only 8.7 × 107 cell mL-1, corresponding to a colonization of 20% of the microcapsule volume. The low level of colonization is unlikely to be due to diffusional limitations since reduction of microcapsule size had no effect. Measurement of cell leaching and mechanical properties showed that liquid core microcapsules are not suitable for continuous long-term cultures (>1 month). By contrast semi-liquid core microcapsules were stable over long periods with a constant level of cell colonization (ϕ = 3%). This indicates that the alginate in the core plays a predominant role in determining the level of microcapsule colonization. This was confirmed by experiments showing reduced growth rates of batch suspension cultures of CHO cells in medium containing dissolved alginate. Removal of this alginate would therefore be expected to increase microcapsule colonization. PMID:19003193

  7. Elongated Microcapsules and Their Formation

    NASA Technical Reports Server (NTRS)

    Calle, Luz M. (Inventor); Li, Wenyan N. (Inventor); Buhrow, Jerry W. (Inventor); Perusich, Stephen A. (Inventor); Jolley, Scott T. (Inventor); Gibson, Tracy L. (Inventor); Williams, Martha K. (Inventor)

    2015-01-01

    Elongated microcapsules, such as elongated hydrophobic-core and hydrophilic-core microcapsules, may be formed by pulse stirring an emulsion or shearing an emulsion between two surfaces moving at different velocities. The elongated microcapsules may be dispersed in a coating formulation, such as paint.

  8. Emulsion-templated liquid core-polymer shell microcapsule formation.

    PubMed

    Ao, Zhuo; Yang, Zhi; Wang, Jianfang; Zhang, Guangzhao; Ngai, To

    2009-03-01

    The fabrication of hollow microspheres to encapsulate functional molecules, such as drugs, insecticides, and proteins, is of ever-increasing importance. Many chemical and physicochemical methods have been tested for various specific encapsulations, but most of them have not been developed into an industrial process. In this work, we present a straightforward method to prepare liquid core-polymer shell microcapsules by first templating an oil-in-water emulsion stabilized by an interfacial monolayer of polystyrene latex particles (often referred to as "Pickering emulsion"), and subsequently locking the assembled particles into a robust polymeric shell through the precipitation of a biodegradable polymer poly(lactic-co-glycolic acid) (PLGA) at the interface. The resultant microcapsules that have a solid polymeric enveloped around the oil droplets are stable and retain their integrity during the drying in air. Therefore, they should have great potential to serve as vehicles for encapsulating functional molecules especially hydrophobic in nature. PMID:19437681

  9. Polydopamine microcapsules with different wall structures prepared by a template-mediated method for enzyme immobilization.

    PubMed

    Shi, Jiafu; Yang, Chen; Zhang, Shaohua; Wang, Xiaoli; Jiang, Zhongyi; Zhang, Wenyan; Song, Xiaokai; Ai, Qinghong; Tian, Chunyong

    2013-10-23

    Microcapsules with diverse wall structures may exhibit different performance in specific applications. In the present study, three kinds of mussel-inspired polydopamine (PDA) microcapsules with different wall structures have been prepared by a template-mediated method. More specifically, three types of CaCO3 microspheres (poly(allylamine hydrochloride), (PAH)-doped CaCO3; pure-CaCO3; and poly(styrene sulfonate sodium), (PSS)-doped CaCO3) were synthesized as sacrificial templates, which were then treated by dopamine to obtain the corresponding PDA-CaCO3 microspheres. Through treating these microspheres with disodium ethylene diamine tetraacetic acid (EDTA-2Na) to remove CaCO3, three types of PDA microcapsules were acquired: that was (1) PAH-PDA microcapsule with a thick (∼600 nm) and highly porous capsule wall composed of interconnected networks, (2) pure-PDA microcapsule with a thick (∼600 nm) and less porous capsule wall, (3) PSS-PDA microcapsule with a thin (∼70 nm) and dense capsule wall. Several characterizations confirmed that a higher degree in porosity and interconnectivity of the capsule wall would lead to a higher mass transfer coefficient. When serving as the carrier for catalase (CAT) immobilization, these enzyme-encapsulated PDA microcapsules showed distinct structure-related activity and stability. In particular, PAH-PDA microcapsules with a wall of highly interconnected networks displayed several significant advantages, including increases in enzyme encapsulation efficiency and enzyme activity/stability and a decrease in enzyme leaching in comparison with other two types of PDA microcapsules. Besides, this hierarchically structured PAH-PDA microcapsule may find other promising applications in biocatalysis, biosensors, drug delivery, etc. PMID:24059356

  10. Synthesis and Characterization of PLGA Shell Microcapsules Containing Aqueous Cores Prepared by Internal Phase Separation.

    PubMed

    Abulateefeh, Samer R; Alkilany, Alaaldin M

    2016-08-01

    The preparation of microcapsules consisting of poly(D,L-lactide-co-glycolide) (PLGA) polymer shell and aqueous core is a clear challenge and hence has been rarely addressed in literature. Herein, aqueous core-PLGA shell microcapsules have been prepared by internal phase separation from acetone-water in oil emulsion. The resulting microcapsules exhibited mean particle size of 1.1 ± 0.39 μm (PDI = 0.35) with spherical surface morphology and internal poly-nuclear core morphology as indicated by scanning electron microscopy (SEM). The incorporation of water molecules into PLGA microcapsules was confirmed by differential scanning calorimetry (DSC). Aqueous core-PLGA shell microcapsules and the corresponding conventional PLGA microspheres were prepared and loaded with risedronate sodium as a model drug. Interestingly, aqueous core-PLGA shell microcapsules illustrated 2.5-fold increase in drug encapsulation in comparison to the classical PLGA microspheres (i.e., 31.6 vs. 12.7%), while exhibiting sustained release behavior following diffusion-controlled Higuchi model. The reported method could be extrapolated to encapsulate other water soluble drugs and hydrophilic macromolecules into PLGA microcapsules, which should overcome various drawbacks correlated with conventional PLGA microspheres in terms of drug loading and release. PMID:26416284

  11. Development and evaluation of novel flavour microcapsules containing vanilla oil using complex coacervation approach.

    PubMed

    Yang, Ziming; Peng, Zheng; Li, Jihua; Li, Sidong; Kong, Lingxue; Li, Puwang; Wang, Qinghuang

    2014-02-15

    A novel flavour microcapsule containing vanilla oil (VO) was developed using complex coacervation approach, aimed to control release of VO and enhance its thermostability for spice application in food industry. Viscosity of chitosan (CS) and VO/CS ratio were optimised for fabrication of microcapsules. The flavour microcapsules were evaluated by scanning electron micrograph (SEM), laser confocal microscopy (LSCM), particle size analyser, infrared spectrometer (FT-IR), thermal analysis and controlled-release analysis. The microcapsules were in spherical with good dispersibility when moderate viscosity CS was used. 94.2% of encapsulation efficiency was achieved in VO/CS ratio of 2:1. The FT-IR study proved chemical cross-linking reaction occurred between genipin and chitosan, but a physical interaction between CS and VO. A core-shell structure of microcapsule was confirmed by LSCM, which was beneficial to improve the thermostability of VO in microcapsule. Moreover, VO could be remained about 60% in the microcapsules after release for 30 days, which demonstrated the flavour microcapsules had good potential to serve as a high quality food spice with long residual action and high thermostability. PMID:24128477

  12. Curcumin delivered through bovine serum albumin/polysaccharides multilayered microcapsules.

    PubMed

    Paşcalău, V; Soritau, O; Popa, F; Pavel, C; Coman, V; Perhaita, I; Borodi, G; Dirzu, N; Tabaran, F; Popa, C

    2016-01-01

    The aim of the paper is to obtain and characterize k-carrageenan-chitosan dual hydrogel multilayers shell BSA gel microcapsules, as a carrier for curcumin, and as a possible antitumoral agent in biological studies. We used the CaCO3 template to synthesize non-toxic CaCO3/BSA particles as microtemplates by coprecipitating a CaCl2 solution that contains dissolved BSA, with an equimolar Na2CO3 solution. The microcapsules shell is assembled through a layer-by-layer deposition technique of calcium cross-linked k-carrageenan hydrogel alternating with polyelectrolite complex hydrogel formed via electrostatic interactions between k-carrageenan and chitosan. After the removal of CaCO3 through Ca(2+) complexation with EDTA, and by a slightly treatment with HCl diluted solution, the BSA core is turned into a BSA gel through a thermal treatment. The BSA gel microcapsules were then loaded with curcumin, through a diffusion process from curcumin ethanolic solution. All the synthesized particles and microcapsules were stucturally characterized by: Fourier Transform Infrared Spectroscopy, UV-Vis Spectrometry, X-ray diffraction, thermal analysis, fluorescence spectroscopy, fluorescence optical microscopy, confocal laser scanning microscopy and scanning electron microscopy. The behavior of curcumin loaded microcapsules in media of different pH (SGF, SIF and PBS) was studied in order to reveal the kinetics and the release profile of curcumin. The in vitro evaluation of the antitumoral activity of encapsulated curcumin microcapsules on HeLa cell line and the primary culture of mesenchymal stem cells is the main reason of the microcapsules synthesis as BSA-based vehicle meant to enhance the biodisponibility of curcumin, whose anti-tumor, anti-oxidant and anti-inflammatory properties are well known. PMID:26350520

  13. Delivering MC3T3-E1 cells into injectable calcium phosphate cement through alginate-chitosan microcapsules for bone tissue engineering*

    PubMed Central

    Qiao, Peng-yan; Li, Fang-fang; Dong, Li-min; Xu, Tao; Xie, Qiu-fei

    2014-01-01

    Objective: To deliver cells deep into injectable calcium phosphate cement (CPC) through alginate-chitosan (AC) microcapsules and investigate the biological behavior of the cells released from microcapsules into the CPC. Methods: Mouse osteoblastic MC3T3-E1 cells were embedded in alginate and AC microcapsules using an electrostatic droplet generator. The two types of cell-encapsulating microcapsules were then mixed with a CPC paste. MC3T3-E1 cell viability was investigated using a Wst-8 kit, and osteogenic differentiation was demonstrated by an alkaline phosphatase (ALP) activity assay. Cell attachment in CPC was observed by an environment scanning electron microscopy. Results: Both alginate and AC microcapsules were able to release the encapsulated MC3T3-E1 cells when mixed with CPC paste. The released cells attached to the setting CPC scaffolds, survived, differentiated, and formed mineralized nodules. Cells grew in the pores concomitantly created by the AC microcapsules in situ within the CPC. At Day 21, cellular ALP activity in the AC group was approximately four times that at Day 7 and exceeded that of the alginate microcapsule group (P<0.05). Pores formed by the AC microcapsules had a diameter of several hundred microns and were spherical compared with those formed by alginate microcapsules. Conclusions: AC microcapsule is a promising carrier to release seeding cells deep into an injectable CPC scaffold for bone engineering. PMID:24711359

  14. Stiffness-Independent Highly Efficient On-Chip Extraction of Cell-Laden Hydrogel Microcapsules from Oil Emulsion into Aqueous Solution by Dielectrophoresis.

    PubMed

    Huang, Haishui; Sun, Mingrui; Heisler-Taylor, Tyler; Kiourti, Asimina; Volakis, John; Lafyatis, Gregory; He, Xiaoming

    2015-10-28

    A dielectrophoresis (DEP)-based method achieves highly efficient on-chip extraction of cell-laden microcapsules of any stiffness from oil into aqueous solution. The hydrogel microcapsules can be extracted into the aqueous solution by DEP and interfacial tension forces with no trapped oil, while the encapsulated cells are free from electrical damage due to the Faraday cage effect. PMID:26297051

  15. Physicochemical properties and storage stability of lutein microcapsules prepared with maltodextrins and sucrose by spray drying.

    PubMed

    Kuang, Pengqun; Zhang, Hongchao; Bajaj, Poonam R; Yuan, Qipeng; Tang, Juming; Chen, Shulin; Sablani, Shyam S

    2015-02-01

    The purpose of this study was to determine the physicochemical properties of lutein microcapsules. Nine types of lutein microcapsules were prepared in order to determine their encapsulation efficiency and yield. Results show that lutein microcapsules with maltodextrin M040 and sucrose at the weight ratio of 3:1 (designated as M040:1) had the highest encapsulation efficiency (90.1%) among the lutein microcapsules, as well as a higher encapsulation yield (90.4%). The onset glass transition temperatures (Tgi ) and the surface dents of the lutein microcapsules decreased as the dextrose equivalent value of maltodextrin and the weight ratio of sucrose increased. Enthalpy relaxation experiments were conducted for the lutein microcapsules M040:1 at (Tgi - 5) , (Tgi - 10), and (Tgi - 15) °C, and the obtained data were fitted to the Kohlrausch-Williams-Watts model. Results show that the mean relaxation time (τ) (316 h) of M040:1 lutein microcapsules aged at (Tgi - 15) °C was greater than the τ (161 h) at (Tgi - 10) °C and τ (60.5 h) at (Tgi - 5) °C. Effects of temperature and oxygen transmission rates for package film on the storage stability of M040:1 lutein microcapsules were also investigated. Findings show that rates of lutein degradation and color change increased by an order of magnitude as storage temperature (4 to 97 °C) and oxygen transmission rate of the package film (0.018 to 62.8 cc/m(2) day) increased. These results suggest that lutein is highly unstable and susceptible to thermal and oxidative degradations. However, microencapsulation with appropriate wall materials of higher relaxation time and high oxygen barrier packaging can increase the storage life. PMID:25597919

  16. Effect of different polysaccharides and crosslinkers on echium oil microcapsules.

    PubMed

    Comunian, Talita A; Gomez-Estaca, Joaquin; Ferro-Furtado, Roselayne; Conceição, Gelson José Andrade; Moraes, Izabel Cristina Freitas; de Castro, Inar Alves; Favaro-Trindade, Carmen S

    2016-10-01

    Microencapsulation by complex coacervation using gelatin and arabic gum (AG) as wall materials and transglutaminase for crosslinking is commonly used. However, AG is only produced in a few countries and transglutaminase is expensive. This work aimed to evaluate the encapsulation of echium oil by complex coacervation using gelatin and cashew gum (CG) as wall materials and sinapic acid (S) as crosslinker. Treatments were analyzed in relation to morphology, particle size, circularity, accelerated oxidation and submitted to different stress conditions. Rounded microcapsules were obtained for treatments with AG (45.45μm) and microcapsules of undefined format were obtained for treatments with CG (22.06μm). The S incorporation for 12h improved the oil stability by three fold compared to oil encapsulated without crosslinkers. Treatments with CG and S were resistant to different stress conditions similar to treatments with AG and transglutaminase, making this an alternative for delivery/application of compounds in food products. PMID:27312643

  17. CdS QDs-chitosan microcapsules with stimuli-responsive property generated by gas-liquid microfluidic technique.

    PubMed

    Chen, Yanjun; Yao, Rongyi; Wang, Yifeng; Chen, Ming; Qiu, Tong; Zhang, Chaocan

    2015-01-01

    This article describes a straightforward gas-liquid microfluidic approach to generate uniform-sized chitosan microcapsules containing CdS quantum dots (QDs). CdS QDs are encapsulated into the liquid-core of the microcapsules. The sizes of the microcapsules can be conveniently controlled by gas flow rate. QDs-chitosan microcapsules show good fluorescent stability in water, and exhibit fluorescent responses to chemical environmental stimuli. α-Cyclodextrin (α-CD) causes the microcapsules to deform and even collapse. More interestingly, α-CD induces obvious changes on the fluorescent color of the microcapsules. However, β-cyclodextrin (β-CD) has little influence on the shape and fluorescent color of the microcapsules. Based on the results of scanning electron microscopy, the possible mechanism about the effects of α-CD on the chitosan microcapsules is analyzed. These stimuli-responsive microcapsules are low-cost and easy to be prepared by gas-liquid microfluidic technique, and can be applied as a potential micro-detector to chemicals, such as CDs. PMID:25460598

  18. Process for Encapsulating Protein Crystals

    NASA Technical Reports Server (NTRS)

    Morrison, Dennis R.; Mosier, Benjamin

    2003-01-01

    A process for growing protein crystals encapsulated within membranes has been invented. This process begins with the encapsulation of a nearly saturated aqueous protein solution inside semipermeable membranes to form microcapsules. The encapsulation is effected by use of special formulations of a dissolved protein and a surfactant in an aqueous first liquid phase, which is placed into contact with a second, immiscible liquid phase that contains one or more polymers that are insoluble in the first phase. The second phase becomes formed into the semipermeable membranes that surround microglobules of the first phase, thereby forming the microcapsules. Once formed, the microcapsules are then dehydrated osmotically by exposure to a concentrated salt or polymer solution. The dehydration forms supersaturated solutions inside the microcapsules, thereby enabling nucleation and growth of protein crystals inside the microcapsules. By suitable formulation of the polymer or salt solution and of other physical and chemical parameters, one can control the rate of transport of water out of the microcapsules through the membranes and thereby create physicochemical conditions that favor the growth, within each microcapsule, of one or a few large crystals suitable for analysis by x-ray diffraction. The membrane polymer can be formulated to consist of low-molecular-weight molecules that do not interfere with the x-ray diffraction analysis of the encapsulated crystals. During dehydration, an electrostatic field can be applied to exert additional control over the rate of dehydration. This protein-crystal-encapsulation process is expected to constitute the basis of protein-growth experiments to be performed on the space shuttle and the International Space Station. As envisioned, the experiments would involve the exposure of immiscible liquids to each other in sequences of steps under microgravitational conditions. The experiments are expected to contribute to knowledge of the precise

  19. In Situ Activation of Microcapsules

    NASA Technical Reports Server (NTRS)

    Morrison, Dennis R. (Inventor); Mosier, Benjamin (Inventor)

    2000-01-01

    Disclosed are microcapsules comprising a polymer shell enclosing two or more immiscible liquid phases in which a drug, or a prodrug and a drug activator are partitioned into separate phases. or prevented from diffusing out of the microcapsule by a liquid phase in which the drug is poorly soluble. Also disclosed are methods of using the microcapsules for in situ activation of drugs where upon exposure to an appropriate energy source the internal phases mix and the drug is activated in situ.

  20. Performance evaluation soil samples utilizing encapsulation technology

    DOEpatents

    Dahlgran, J.R.

    1999-08-17

    Performance evaluation soil samples and method of their preparation uses encapsulation technology to encapsulate analytes which are introduced into a soil matrix for analysis and evaluation by analytical laboratories. Target analytes are mixed in an appropriate solvent at predetermined concentrations. The mixture is emulsified in a solution of polymeric film forming material. The emulsified solution is polymerized to form microcapsules. The microcapsules are recovered, quantitated and introduced into a soil matrix in a predetermined ratio to form soil samples with the desired analyte concentration. 1 fig.

  1. Performance evaluation soil samples utilizing encapsulation technology

    DOEpatents

    Dahlgran, James R.

    1999-01-01

    Performance evaluation soil samples and method of their preparation using encapsulation technology to encapsulate analytes which are introduced into a soil matrix for analysis and evaluation by analytical laboratories. Target analytes are mixed in an appropriate solvent at predetermined concentrations. The mixture is emulsified in a solution of polymeric film forming material. The emulsified solution is polymerized to form microcapsules. The microcapsules are recovered, quantitated and introduced into a soil matrix in a predetermined ratio to form soil samples with the desired analyte concentration.

  2. Ultrasonic synthesis of stable oil filled microcapsules using thiolated chitosan and their characterization by AFM and numerical simulations.

    PubMed

    Tan, Sinuo; Mettu, Srinivas; Biviano, Matthew Dominic; Zhou, Meifang; Babgi, Bandar; White, Jonathan; Dagastine, Raymond R; Ashokkumar, Muthupandian

    2016-09-14

    An experimental protocol has been developed for synthesizing stable core-shell microcapsules using a biopolymer, chitosan, lacking cross-linkable thiol functional groups. In the first step, thiol moieties were introduced into the backbone of chitosan using dl-N-acetylhomocysteine thiolactone (AHT). In the second step, AHT-modified chitosan shelled microcapsules, encapsulating an oil core, were successfully prepared using high intensity 20 kHz ultrasound. The size of chitosan and AHT modified chitosan microcapsules was found to be in the range of 1-15 μm. The thickness of the microcapsule shell increased with an increase in thiol content. The mechanical properties of microcapsules were evaluated by subjecting the microcapsules to compressive forces by colloidal probe AFM. The stiffness and the Young's modulus of the shell of microcapsules were determined by analyzing the force versus indentation data using Reissner's theory for indentation of thin elastic shells. The stiffness of AHT modified chitosan microcapsules was found to be higher than unmodified chitosan microcapsules. The viability of microcapsules to be embedded into processed food, pharmaceutical and cosmetic products was tested via numerical simulations. The confined capsule in the micro-channel was subjected to linear shear and uniform flows. We used finite element numerical simulations to determine the deformation of microcapsules in flow as a function of shear rate and thickness of the shell. The deformation of capsule was found to be linear with an increase in the shear rate. The deformation decreased with an increase in the thickness of the shell. Based on the simulations, we predict that the microcapsules would survive processing conditions and shear rates used in industrial applications. PMID:27499242

  3. Preparation of microcapsules with the evaluation of physicochemical properties and molecular interaction.

    PubMed

    Kim, Ki Hyun; Cho, Su-Ah; Lim, Jun Yeul; Lim, Dae Gon; Moon, Cheol; Jeong, Seong Hoon

    2014-12-01

    The objective of this study was to prepare and characterize dutasteride (a hydrophobic model drug) microcapsules using ethyl cellulose as a capsule shell polymer with different drug/polymer ratios of 1:1, 1:3, and 1:5. The microcapsules were prepared by a solvent evaporation method and the prepared microcapsules were evaluated for percent yield, percent drug content, encapsulation efficiency, particle size distribution, scanning electron microscopy (SEM), differential scanning calorimetry (DSC), Fourier transform infrared (FT-IR) spectroscopy, powder X-ray diffraction (PXRD), and in vitro drug release studies. SEM revealed the spherical shape of all prepared microcapsules. The particle size of the microcapsules was about 95-119 μm with good yield and encapsulation efficiency. PXRD showed different X-ray patterns compared to the drug itself suggesting possibility of crystalline form change during the process. Moreover, it confirmed that ethyl cellulose was changed to amorphous state. The physical property changes may affect the overall quality and drug release behavior. In the FT-IR studies, hydrogen bonding was observed between the drug and polymer at the molecular level. DSC data provided consistent results with the FT-IR and PXRD analyses. Drug release profiles showed the overall sustained release of drug and anomalous diffusion mechanism based on the Korsmeyer-Peppas equation. Understanding the physicochemical properties of a drug and polymer including molecular interactions may facilitate formulation of microcapsules with acceptable properties and drug release behaviors. PMID:24338504

  4. Alpha-2-macroglobulin loaded microcapsules enhance human leukocyte functions and innate immune response

    PubMed Central

    Canova, Donata Federici; Pavlov, Anton M.; Norling, Lucy V.; Gobbetti, Thomas; Brunelleschi, Sandra; Le Fauder, Pauline; Cenac, Nicolas; Sukhorukov, Gleb B.; Perretti, Mauro

    2015-01-01

    Synthetic microstructures can be engineered to deliver bioactive compounds impacting on their pharmacokinetics and pharmacodynamics. Herein, we applied dextran-based layer-by-layer (LbL) microcapsules to deliver alpha-2-macroglobulin (α2MG), a protein with modulatory properties in inflammation. Extending recent observations made with dextran-microcapsules loaded with α2MG in experimental sepsis, we focused on the physical and chemical characteristics of these microstructures and determined their biology on rodent and human cells. We report an efficient encapsulation of α2MG into microcapsules, which enhanced i) human leukocyte recruitment to inflamed endothelium and ii) human macrophage phagocytosis: in both settings microcapsules were more effective than soluble α2MG or empty microcapsules (devoid of active protein). Translation of these findings revealed that intravenous administration of α2MG-microcapsules (but not empty microcapsules) promoted neutrophil migration into peritoneal exudates and augmented macrophage phagocytic functions, the latter response being associated with alteration of bioactive lipid mediators as assessed by mass spectrometry. The present study indicates that microencapsulation can be an effective strategy to harness the complex biology of α2MG with enhancing outcomes on fundamental processes of the innate immune response paving the way to potential future development in the control of sepsis. PMID:26385167

  5. Alpha-2-macroglobulin loaded microcapsules enhance human leukocyte functions and innate immune response.

    PubMed

    Federici Canova, Donata; Pavlov, Anton M; Norling, Lucy V; Gobbetti, Thomas; Brunelleschi, Sandra; Le Fauder, Pauline; Cenac, Nicolas; Sukhorukov, Gleb B; Perretti, Mauro

    2015-11-10

    Synthetic microstructures can be engineered to deliver bioactive compounds impacting on their pharmacokinetics and pharmacodynamics. Herein, we applied dextran-based layer-by-layer (LbL) microcapsules to deliver alpha-2-macroglobulin (α2MG), a protein with modulatory properties in inflammation. Extending recent observations made with dextran-microcapsules loaded with α2MG in experimental sepsis, we focused on the physical and chemical characteristics of these microstructures and determined their biology on rodent and human cells. We report an efficient encapsulation of α2MG into microcapsules, which enhanced i) human leukocyte recruitment to inflamed endothelium and ii) human macrophage phagocytosis: in both settings microcapsules were more effective than soluble α2MG or empty microcapsules (devoid of active protein). Translation of these findings revealed that intravenous administration of α2MG-microcapsules (but not empty microcapsules) promoted neutrophil migration into peritoneal exudates and augmented macrophage phagocytic functions, the latter response being associated with alteration of bioactive lipid mediators as assessed by mass spectrometry. The present study indicates that microencapsulation can be an effective strategy to harness the complex biology of α2MG with enhancing outcomes on fundamental processes of the innate immune response paving the way to potential future development in the control of sepsis. PMID:26385167

  6. In Vivo Magnetic Resonance Imaging and Microwave Thermotherapy of Cancer Using Novel Chitosan Microcapsules

    NASA Astrophysics Data System (ADS)

    Tang, Shunsong; Du, Qijun; Liu, Tianlong; Tan, Longfei; Niu, Meng; Gao, Long; Huang, Zhongbing; Fu, Changhui; Ma, Tengchuang; Meng, Xianwei; Shao, Haibo

    2016-07-01

    Herein, we develop a novel integrated strategy for the preparation of theranostic chitosan microcapsules by encapsulating ion liquids (ILs) and Fe3O4 nanoparticles. The as-prepared chitosan/Fe3O4@IL microcapsules exhibit not only significant heating efficacy in vitro under microwave (MW) irradiation but also obvious enhancement of T2-weighted magnetic resonance (MR) imaging, besides the excellent biocompatibility in physiological environments. The chitosan/Fe3O4@IL microcapsules show ideal temperature rise and therapeutic efficiency when applied to microwave thermal therapy in vivo. Complete tumor elimination is realizing after MW irradiation at an ultralow power density (1.8 W/cm2), while neither the MW group nor the chitosan microcapsule group has significant influence on the tumor development. The applicability of the chitosan/Fe3O4@IL microcapsules as an efficient contrast agent for MR imaging is proved in vivo. Moreover, the result of in vivo systematic toxicity shows that chitosan/Fe3O4@IL microcapsules have no acute fatal toxicity. Our study presents an interesting type of multifunctional platform developed by chitosan microcapsule promising for imaging-guided MW thermotherapy.

  7. In Vivo Magnetic Resonance Imaging and Microwave Thermotherapy of Cancer Using Novel Chitosan Microcapsules.

    PubMed

    Tang, Shunsong; Du, Qijun; Liu, Tianlong; Tan, Longfei; Niu, Meng; Gao, Long; Huang, Zhongbing; Fu, Changhui; Ma, Tengchuang; Meng, Xianwei; Shao, Haibo

    2016-12-01

    Herein, we develop a novel integrated strategy for the preparation of theranostic chitosan microcapsules by encapsulating ion liquids (ILs) and Fe3O4 nanoparticles. The as-prepared chitosan/Fe3O4@IL microcapsules exhibit not only significant heating efficacy in vitro under microwave (MW) irradiation but also obvious enhancement of T2-weighted magnetic resonance (MR) imaging, besides the excellent biocompatibility in physiological environments. The chitosan/Fe3O4@IL microcapsules show ideal temperature rise and therapeutic efficiency when applied to microwave thermal therapy in vivo. Complete tumor elimination is realizing after MW irradiation at an ultralow power density (1.8 W/cm(2)), while neither the MW group nor the chitosan microcapsule group has significant influence on the tumor development. The applicability of the chitosan/Fe3O4@IL microcapsules as an efficient contrast agent for MR imaging is proved in vivo. Moreover, the result of in vivo systematic toxicity shows that chitosan/Fe3O4@IL microcapsules have no acute fatal toxicity. Our study presents an interesting type of multifunctional platform developed by chitosan microcapsule promising for imaging-guided MW thermotherapy. PMID:27422776

  8. Study on the grafting of chitosan-gelatin microcapsules onto cotton fabrics and its antibacterial effect.

    PubMed

    Liu, Jiayi; Liu, Chaohong; Liu, Yingju; Chen, Minjie; Hu, Yang; Yang, Zhuohong

    2013-09-01

    In this work, patchouli oil embedded chitosan-gelatin microcapsules were prepared by the complex coacervation method. Their surface and morphology were characterized by scanning electron microscopy (SEM), showing that the microcapsules were with a regular spherical shape in the range of 1 and 20 μm. In the thermal stability analysis, the microcapsules were stable below 190°C, which indicated the fabrics finish can be conducted at 160°C. The encapsulation efficiency (EE) and loading capacity (LC) of the microcapsules were calculated as 50.69% and 30.31%, respectively. Then, the microcapsules were grafted onto cotton fabrics using 2D resin (dimethyloldihydroxyethylene urea, DMDHEU) as the crosslinking reagent. SEM showed that the microcapsules were not only grafted on the surface of the fabrics, but also inserted in the spacing of the fibers. In addition, the formation of ether bonds between 2D resin and hydroxyl groups of cotton and/or hydroxyl groups of the microcapsules was identified by Fourier transform infrared spectroscopy (FTIR). Finally, the antibacterial rate of the fabrics for Staphylococcus aureus and Escherichia coli were about 65% even after being washed 25 times, suggesting its potential application in many fields such as antibacterial mask, bacteriostatic sheet and health-care clothes. PMID:23624277

  9. Nozzleless Fabrication of Oil-Core Biopolymeric Microcapsules by the Interfacial Gelation of Pickering Emulsion Templates.

    PubMed

    Leong, Jun-Yee; Tey, Beng-Ti; Tan, Chin-Ping; Chan, Eng-Seng

    2015-08-01

    Ionotropic gelation has been an attractive method for the fabrication of biopolymeric oil-core microcapsules due to its safe and mild processing conditions. However, the mandatory use of a nozzle system to form the microcapsules restricts the process scalability and the production of small microcapsules (<100 μm). We report, for the first time, a nozzleless and surfactant-free approach to fabricate oil-core biopolymeric microcapsules through ionotropic gelation at the interface of an O/W Pickering emulsion. This approach involves the self-assembly of calcium carbonate (CaCO3) nanoparticles at the interface of O/W emulsion droplets followed by the addition of a polyanionic biopolymer into the aqueous phase. Subsequently, CaCO3 nanoparticles are dissolved by pH reduction, thus liberating Ca(2+) ions to cross-link the surrounding polyanionic biopolymer to form a shell that encapsulates the oil droplet. We demonstrate the versatility of this method by fabricating microcapsules from different types of polyanionic biopolymers (i.e., alginate, pectin, and gellan gum) and water-immiscible liquid cores (i.e., palm olein, cyclohexane, dichloromethane, and toluene). In addition, small microcapsules with a mean size smaller than 100 μm can be produced by selecting the appropriate conventional emulsification methods available to prepare the Pickering emulsion. The simplicity and versatility of this method allows biopolymeric microcapsules to be fabricated with ease by ionotropic gelation for numerous applications. PMID:26148344

  10. Externally triggered microcapsules

    NASA Technical Reports Server (NTRS)

    Morrison, Dennis R. (Inventor); Mosier, Benjamin (Inventor)

    2011-01-01

    Disclosed are microcapsules comprising a polymer shell enclosing one or more immiscible liquid phases in which a drug or drug precursor are contained in a liquid phase. The microparticles also contain magnetic particles that can be heated by application of an external magnetic field and thus heated to a predetermined Curie temperature. Heating of the particles melts the polymer shell and releases the drug without causing heating of surrounding tissues.

  11. Preparation and evaluation of Bacillus megaterium-alginate microcapsules for control of rice sheath blight disease.

    PubMed

    Wiwattanapatapee, R; Chumthong, A; Pengnoo, A; Kanjanamaneesathian, M

    2013-08-01

    Bacillus megaterium encapsulated in calcium alginate microcapsules was prepared and tested for its efficacy against sheath blight disease of rice. In laboratory conditions, the aqueous suspension (1:100, v/v in potato dextrose agar) of the bacterial microcapsules (10(10) spores/ml) inhibited mycelial growth of Rhizoctonia solani (>99 %) after the microcapsules were produced and stored for 12 months at room temperature (28 ± 2 °C). The survival of the bacterium in the microcapsules in response to ultraviolet (u.v.) irradiation and high temperature was investigated. The survivability of the bacterium in the encapsulated form was greater than that of the fresh cells when it was subjected to u.v. (20-W General electric u.v. lamp from a 25 cm distance for 48 h) and a high temperature treatment (80 °C for 48 h). Cells of the bacterium were detected by scanning electron microscope on both the leaf sheath and the leaf blade (in pot tests in a greenhouse) after spraying encapsulated product. The number of bacteria on the surface of both rice tissues (5 Log. number/g of plant) after spraying with encapsulated product was not significantly different from that after spraying with fresh cells onto the rice seedlings. Spraying the encapsulated B. megaterium on rice plants in the greenhouse was as effective as spraying a chemical fungicide for suppressing rice sheath blight disease. PMID:23508397

  12. Prolonged release terbutaline sulphate microcapsules.

    PubMed

    Manekar, N C; Puranik, P K; Joshi, S B

    1991-01-01

    Terbutaline sulphate microcapsules were prepared by coacervation-phase separation induced by solvent evaporation technique. The cellulose acetate phthalate was employed as coating material alone and in combination with ethyl cellulose. The prepared microcapsules were evaluated for their drug content, particle size distribution (microscopic method), flow properties, bulk density and in vitro dissolution. PMID:1798022

  13. Physical Properties and Stabilization of Microcapsules Containing Thyme Oil by Complex Coacervation.

    PubMed

    Shen, Lili; Chen, Jiaping; Bai, Youju; Ma, Zhican; Huang, Jing; Feng, Wu

    2016-09-01

    The aim of this study was to produce and characterize microcapsules of thyme oil and finally appraise the extent of stability improvement. The optimum process conditions obtained from orthogonal tests were as follows: ratio of core material to wall 0.5, temperature 40 °C, pH value 3.0 and time 20 min, where the practical encapsulation efficiency was 85.17±1.35%. The microcapsules belong to the nanometric range as the average particle diameter was 531.17±77.12 nm. The results from structural analysis indicated that no significant chemical bond occurred during the encapsulation process and the microcapsules remained stable when the encapsulation was conducted at a temperature below 53.1 °C. Especially, the retention rate of thyme oil in microcapsules remained 39.21% at 4 °C, 36.99% at 25 °C and 33.80% at 40 °C after 30 d of storage. Moreover, protection from light exposure presented a positive impact on the storage stability of thyme oil microcapsules. PMID:27472246

  14. Research of Amoxicillin Microcapsules Preparation Playing Micro-Jetting Technology

    PubMed Central

    Sun, Huaiyuan; Gu, Qingqing; Liao, Yuehua; Sun, Chenjie

    2015-01-01

    With polylactic-co-glycolic acid(PLGA) as shell material of microcapsule, amoxicillin as the model, poly(vinyl alcohol) and twain as surfactant, amoxicillin-PLGA microcapsules were manufactured using digital micro-jetting technology and a glass nozzle of 40μm diameter. The influences of the parameters of micro-jetting system on the mean grain size and size distribution of amoxicillin-PLGA microcapsules were studied with single factor analysis and orthogonal experiment method, namely, PLGA solution concentration, driving voltage, jetting frequency, stirrer speed, etc. The optimal result was obtained; the form representation of microcapsule was analyzed as well. The results show that, under certain conditions of experimental drug prescription, driving voltage was proportional to the particle size; jetting frequency and stirrer speed were inversely proportional. When the PLGA concentration for 3%, driving voltage for 80V, the jetting frequency for 10000Hz and the stirrer speed for 750rpm, the particles were in an ideal state with the mean grain size of 60.246μm, the encapsulation efficiency reached 62.39% and 2.1% for drug loading. PMID:25937851

  15. Research of amoxicillin microcapsules preparation playing micro-jetting technology.

    PubMed

    Sun, Huaiyuan; Gu, Qingqing; Liao, Yuehua; Sun, Chenjie

    2015-01-01

    With polylactic-co-glycolic acid(PLGA) as shell material of microcapsule, amoxicillin as the model, poly(vinyl alcohol) and twain as surfactant, amoxicillin-PLGA microcapsules were manufactured using digital micro-jetting technology and a glass nozzle of 40μm diameter. The influences of the parameters of micro-jetting system on the mean grain size and size distribution of amoxicillin-PLGA microcapsules were studied with single factor analysis and orthogonal experiment method, namely, PLGA solution concentration, driving voltage, jetting frequency, stirrer speed, etc. The optimal result was obtained; the form representation of microcapsule was analyzed as well. The results show that, under certain conditions of experimental drug prescription, driving voltage was proportional to the particle size; jetting frequency and stirrer speed were inversely proportional. When the PLGA concentration for 3%, driving voltage for 80V, the jetting frequency for 10000Hz and the stirrer speed for 750rpm, the particles were in an ideal state with the mean grain size of 60.246μm, the encapsulation efficiency reached 62.39% and 2.1% for drug loading. PMID:25937851

  16. Production of cell-enclosing hollow-core agarose microcapsules via jetting in water-immiscible liquid paraffin and formation of embryoid body-like spherical tissues from mouse ES cells enclosed within these microcapsules.

    PubMed

    Sakai, Shinji; Hashimoto, Ichiro; Kawakami, Koei

    2008-01-01

    We developed agarose microcapsules with a single hollow core templated by alginate microparticles using a jet-technique. We extruded an agarose aqueous solution containing suspended alginate microparticles into a coflowing stream of liquid paraffin and controlled the diameter of the agarose microparticles by changing the flow rate of the liquid paraffin. Subsequent degradation of the inner alginate microparticles using alginate lyase resulted in the hollow-core structure. We successfully obtained agarose microcapsules with 20-50 microm of agarose gel layer thickness and hollow cores ranging in diameter from ca. 50 to 450 microm. Using alginate microparticles of ca. 150 microm in diameter and enclosing feline kidney cells, we were able to create cell-enclosing agarose microcapsules with a hollow core of ca. 150 microm in diameter. The cells in these microcapsules grew much faster than those in alginate microparticles. In addition, we enclosed mouse embryonic stem cells in agarose microcapsules. The embryonic stem cells began to self-aggregate in the core just after encapsulation, and subsequently grew and formed embryoid body-like spherical tissues in the hollow core of the microcapsules. These results show that our novel microcapsule production technique and the resultant microcapsules have potential for tissue engineering, cell therapy and biopharmaceutical applications. PMID:17705234

  17. Propagation of human iPS cells in alginate-based microcapsules prepared using reactions catalyzed by horseradish peroxidase and catalase.

    PubMed

    Ashida, Tomoaki; Sakai, Shinji; Taya, Masahito

    2016-09-01

    Cell encapsulation has been investigated as a bioproduction system in the biomedical and pharmaceutical fields. We encaps-ulated human induced pluripotent stem (hiPS) cells in duplex microcapsules prepared from an alginate derivative possessing phenolic hydroxyl moieties, in a single-step procedure based on two competing enzymatic reactions catalyzed by horseradish peroxidase (HRP) and catalase. The encapsulated cells maintained 91.4% viability and proliferated to fill the microcapsules following 19 days of culture. Encapsulated hiPS cells showed pluripotency comparable to that of unencapsulated cells during the cultures, as demonstrated by the expression of the SSEA-4 marker. PMID:26148179

  18. Controlled Delivery of Human Cells by Temperature Responsive Microcapsules

    PubMed Central

    Mak, W.C.; Olesen, K.; Sivlér, P.; Lee, C.J.; Moreno-Jimenez, I.; Edin, J.; Courtman, D.; Skog, M.; Griffith, M.

    2015-01-01

    Cell therapy is one of the most promising areas within regenerative medicine. However, its full potential is limited by the rapid loss of introduced therapeutic cells before their full effects can be exploited, due in part to anoikis, and in part to the adverse environments often found within the pathologic tissues that the cells have been grafted into. Encapsulation of individual cells has been proposed as a means of increasing cell viability. In this study, we developed a facile, high throughput method for creating temperature responsive microcapsules comprising agarose, gelatin and fibrinogen for delivery and subsequent controlled release of cells. We verified the hypothesis that composite capsules combining agarose and gelatin, which possess different phase transition temperatures from solid to liquid, facilitated the destabilization of the capsules for cell release. Cell encapsulation and controlled release was demonstrated using human fibroblasts as model cells, as well as a therapeutically relevant cell line—human umbilical vein endothelial cells (HUVECs). While such temperature responsive cell microcapsules promise effective, controlled release of potential therapeutic cells at physiological temperatures, further work will be needed to augment the composition of the microcapsules and optimize the numbers of cells per capsule prior to clinical evaluation. PMID:26096147

  19. Use of microcapsules as controlled release devices for coatings.

    PubMed

    Andersson Trojer, Markus; Nordstierna, Lars; Bergek, Jonatan; Blanck, Hans; Holmberg, Krister; Nydén, Magnus

    2015-08-01

    Biofouling of surfaces is a considerable problem in many industrial sectors and for the public community in general. The problem is usually approached by the use of functional coatings and most of such antifouling coatings rely on the effect of biocides. However, a substantial drawback is the poor control over the release of the biocide as well as its degradation in the paint. Encapsulation of the biocides in microcapsules is a promising approach that may overcome some of the problems associated with the more traditional ways of incorporating the antifouling agent into the formulation. In this review, we summarize more than a decade of microcapsule research from our lab as well as from other groups working on this topic. Focus will be on two coacervation-based encapsulation techniques; the internal phase separation method and the double emulsion method, which together enable the encapsulation of a broad spectrum of biocides with different physicochemical properties. The release of the biocide from core-shell particles and from encapsulated biocides in coatings is treated in detail. The release behaviour is interpreted in terms of the physicochemical properties of the core-shell particle and the coating matrix. In addition, special attention is given to the experimental release methodology and the implementation of proper diffusion models to describe the release. At the end of the review examples of antifouling properties of some coatings against common biofoulers are presented. PMID:25441449

  20. Holy basil (Ocimum sanctum Linn.) essential oil delivery to swine gastrointestinal tract using gelatin microcapsules coated with aluminum carboxymethyl cellulose and beeswax.

    PubMed

    Chitprasert, Pakamon; Sutaphanit, Polin

    2014-12-31

    Holy basil essential oil (HBEO) can be applied as a feed additive; however, its benefits depend on the available amount in the gastrointestinal tract. In this study, the physicochemical properties, including the release properties of three different microcapsules, HBEO-loaded gelatin microcapsules (UC), UC coated with aluminum carboxymethyl cellulose (CC), and UC coated with aluminum carboxymethyl cellulose-beeswax composite (CB), were compared. The encapsulation efficiency, HBEO content, and 2,2-diphenyl-2-picrylhydrazyl radical scavenging activity for the microcapsules were 95.4 ± 0.17%, 66.7-67.7%, and 94.3-96.5%, respectively. Scanning electron microscopy and confocal laser scanning microscopy (CLSM) revealed nonuniform HBEO distributions in honeycomb-like networks in the microcapsules. An X-ray diffraction analysis determined that UC and CC microcapsules were amorphous, but CB microcapsules were semicrystalline. UV-vis spectrophotometer and CLSM analyses results determined that HBEO was released from CC and CB microcapsules in greater amounts than from UC microcapsules in simulated intestinal fluid. Therefore, the HBEO amount reaching the intestine can be controlled using the optimal encapsulation system. PMID:25382222

  1. Metal-organic coordination-enabled layer-by-layer self-assembly to prepare hybrid microcapsules for efficient enzyme immobilization.

    PubMed

    Wang, Xiaoli; Jiang, Zhongyi; Shi, Jiafu; Liang, Yanpeng; Zhang, Chunhong; Wu, Hong

    2012-07-25

    A novel layer-by-layer self-assembly approach enabled by metal-organic coordination was developed to prepare polymer-inorganic hybrid microcapsules. Alginate was first activated via N-ethyl-N'-(3-dimethylaminopropyl) carbodiimide (EDC) and N-hydroxy succinimide (NHS) coupling chemistry, and subsequently reacted with dopamine. Afterward, the dopamine modified alginate (Alg-DA) and titanium(IV) bis(ammonium lactato) dihydroxide (Ti(IV)) were alternatively deposited onto CaCO3 templates. The coordination reaction between the catechol groups of Alg-DA and the Ti(IV) allowed the alternative assembly to form a series of multilayers. After removing the templates, the alginate-titanium hybrid microcapsules were obtained. The high mechanical stability of hybrid microcapsules was demonstrated by osmotic pressure experiment. Furthermore, the hybrid microcapsules displayed superior thermal stability due to Ti(IV) coordination. Catalase (CAT) was used as model enzyme, either encapsulated inside or covalently attached on the surface of the resultant microcapsules. No CAT leakage from the microcapsules was detected after incubation for 48 h. The encapsulated CAT, with a loading capacity of 450-500 mg g(-1) microcapsules, exhibited desirable long-term storage stability, whereas the covalently attached CAT, with a loading capacity of 100-150 mg g(-1) microcapsules, showed desirable operational stability. PMID:22724538

  2. Electrostatically Directed Self-Assembly of Ultrathin Supramolecular Polymer Microcapsules

    PubMed Central

    Parker, Richard M; Zhang, Jing; Zheng, Yu; Coulston, Roger J; Smith, Clive A; Salmon, Andrew R; Yu, Ziyi; Scherman, Oren A; Abell, Chris

    2015-01-01

    Supramolecular self-assembly offers routes to challenging architectures on the molecular and macroscopic scale. Coupled with microfluidics it has been used to make microcapsules—where a 2D sheet is shaped in 3D, encapsulating the volume within. In this paper, a versatile methodology to direct the accumulation of capsule-forming components to the droplet interface using electrostatic interactions is described. In this approach, charged copolymers are selectively partitioned to the microdroplet interface by a complementary charged surfactant for subsequent supramolecular cross-linking via cucurbit[8]uril. This dynamic assembly process is employed to selectively form both hollow, ultrathin microcapsules and solid microparticles from a single solution. The ability to dictate the distribution of a mixture of charged copolymers within the microdroplet, as demonstrated by the single-step fabrication of distinct core–shell microcapsules, gives access to a new generation of innovative self-assembled constructs. PMID:26213532

  3. Aluminum carboxymethyl cellulose-rice bran microcapsules: enhancing survival of Lactobacillus reuteri KUB-AC5.

    PubMed

    Chitprasert, Pakamon; Sudsai, Polin; Rodklongtan, Akkaratch

    2012-09-01

    This research aimed to enhance the survival of Lactobacillus reuteri KUB-AC5 from heat conditioning by using microencapsulation with aluminum carboxymethyl cellulose-rice bran (AlCMC-RB) composites of different weight ratios of 1:0, 1:1, and 1:1.5. The cell/polymer suspension was crosslinked with aluminum chloride at different agitation speeds of 1200, 1500, and 2100 rpm. The AlCMC microcapsules had significantly higher encapsulation efficiency, but lower microcapsule yield than the AlCMC-RB microcapsules (p≤0.05). Scanning electron microscopy revealed the complexation between AlCMC and RB. Fourier transform infrared spectroscopy showed hydrogen bondings between AlCMC, RB, and cells. The AlCMC-RB microcapsules had significantly lower aluminum ion and moisture contents than the AlCMC ones. After heat exposure, the viability of non-encapsulated and microencapsulated cells in the AlCMC matrix dramatically declined, while that of microencapsulated cells in the AlCMC-RB matrix was about 8 log CFU/g. The results showed the promising potential of the AlCMC-RB composite microcapsules for the protection of probiotics against heat. PMID:24751013

  4. Reconfigurable structure

    NASA Technical Reports Server (NTRS)

    Curtis, Steven A. (Inventor)

    2010-01-01

    A reconfigurable structure includes a plurality of selectively extensible and retractable limbs, at least one node pivotably receiving respective ends of at least two limbs, and an actuator associated with each limb for extending and retracting the limb. The structure may further include an addressable module associated with each actuator to control the actuator.

  5. Competing two enzymatic reactions realizing one-step preparation of cell-enclosing duplex microcapsules.

    PubMed

    Ashida, Tomoaki; Sakai, Shinji; Taya, Masahito

    2013-01-01

    The usefulness of cell-enclosing microcapsules in biomedical and biopharmaceutical fields is widely recognized. In this study, we developed a method enabling the preparation of microcapsules with a liquid core in one step using two enzymatic reactions, both of which consume H2 O2 competitively. The microcapsule membrane prepared in this study is composed of the hydrogel obtained from an alginate derivative possessing phenolic hydroxyl moieties (Alg-Ph). The cell-enclosing microcapsules with a hollow core were obtained by extruding an aqueous solution of Alg-Ph containing horseradish peroxidase (HRP), catalase, and cells into a co-flowing stream of liquid paraffin containing H2 O2 . Formation of the microcapsule membrane progressed from the surface of the droplets through HRP-catalyzed cross-linking of Ph moieties by consuming H2 O2 supplied from the ambient liquid paraffin. A hollow core structure was induced by catalase-catalyzed decomposition of H2 O2 resulting in the center region being at an insufficient level of H2 O2 . The viability of HeLa cells was 93.1% immediately after encapsulation in the microcapsules with about 250 µm diameter obtained from an aqueous solution of 2.5% (w/v) Alg-Ph, 100 units mL(-1) HRP, 9.1 × 10(4) units mL(-1) catalase. The enclosed cells grew much faster than those in the microparticles with a solid core. In addition, the thickness of microcapsule membrane could be controlled by changing the concentrations of HRP and catalase in the range of 13-48 µm. The proposed method could be versatile for preparing the microcapsules from the other polymer derivatives of carboxymetylcellulose and gelatin. PMID:23955874

  6. pH Responsive Microcapsules for Corrosion Control

    NASA Technical Reports Server (NTRS)

    Calle, Luz Marina; Li, Wenyan; Muehlberg, Aaron; Boraas, Samuel; Webster, Dean; JohnstonGelling, Victoria; Croll, Stuart; Taylor, S Ray; Contu, Francesco

    2008-01-01

    The best coatings for corrosion protection provide not only barriers to the environment, but also a controlled release of a corrosion inhibitor, as demanded by the presence of corrosion or mechanical damage. NASA has developed pH sensitive microcapsules (patent pending) that can release their core contents when corrosion starts. The objectives of the research presented here were to encapsulate non-toxic corrosion inhibitors, to incorporate the encapsulated inhibitors into paint formulations, and to test the ability of the paints to control corrosion. Results showed that the encapsulated corrosion inhibitors, specifically Ce(NO3)3 , are effective to control corrosion over long periods of time when incorporated at relatively high pigment volume concentrations into a paint formulation.

  7. Application of microencapsulation for toxicology studies. I. Principles and stabilization of trichloroethylene in gelatin-sorbitol microcapsules.

    PubMed

    Melnick, R L; Jameson, C W; Goehl, T J; Kuhn, G O

    1987-05-01

    Microencapsulation is an innovative, alternative means of incorporating volatile, reactive, and/or unpalatable chemicals into animal feed for toxicologic studies. For such usage, the materials in the microcapsule shell must not adversely affect the laboratory animals, and the encapsulation process must not alter the chemical under study. Trichloroethylene (TCE), a volatile chemical identified in drinking water, was encapsulated in gelatin-sorbitol microcapsules. The concentration of TCE ranged from 40 to 43% (w/w) and most particles (approximately 85%) were between 300 and 420 micron in diameter. Under optimum storage conditions, loss of TCE from the microcapsules was less than 1% per month. Less than 2% of the TCE was lost from microcapsules held in uncovered petri dishes at ambient temperature and humidity for 14 days. Microencapsulated TCE was mixed with NIH-07 rodent feed at a level of 50 mg microcapsules/g feed (equivalent to 20.6 mg TCE/g feed) and stored at room temperature for 7 days in an open container or for 21 days in a sealed container. There was no detectable loss of TCE from the feed blends stored under these conditions. Thus, the stability of TCE in gelatin-sorbitol microcapsules is adequate for dosed-feed toxicity studies of this chemical. PMID:3609532

  8. Biointerfacing polymeric microcapsules for in vivo near-infrared light-triggered drug release

    NASA Astrophysics Data System (ADS)

    Shao, Jingxin; Xuan, Mingjun; Si, Tieyan; Dai, Luru; He, Qiang

    2015-11-01

    Seeking safe and effective water-soluble drug carriers is of great significance in nanomedicine. To achieve this goal, we present a novel drug delivery system based on biointerfacing hollow polymeric microcapsules for effectively encapsulating water-soluble antitumor drug and gold nanorod (GNR) functionalization for triggered release of therapeutic drugs on-demand using low power near-infrared (NIR) radiation. The surface of polymeric microcapsules is covered with fluidic lipid bilayers to decrease the permeability of the wall of polymeric capsules. The temperature increase upon NIR illumination deconstructs the structure of the lipid membrane and polyelectrolyte multilayers, which in turn results in the rapid release of encapsulated water-soluble drug. In vivo antitumor tests demonstrate that this microcapsule has the effective ability of inhibiting tumor growth and preventing metastases. Real time in vivo fluorescence imaging results confirm that capsules can be excreted gradually from the animal body which in turn demonstrates the biocompatibility and biodegradation of these biointerfacing GNR-microcapsules. This intelligent system provides a novel anticancer platform with the advantages of controlled release, biological friendliness and credible biosafety.Seeking safe and effective water-soluble drug carriers is of great significance in nanomedicine. To achieve this goal, we present a novel drug delivery system based on biointerfacing hollow polymeric microcapsules for effectively encapsulating water-soluble antitumor drug and gold nanorod (GNR) functionalization for triggered release of therapeutic drugs on-demand using low power near-infrared (NIR) radiation. The surface of polymeric microcapsules is covered with fluidic lipid bilayers to decrease the permeability of the wall of polymeric capsules. The temperature increase upon NIR illumination deconstructs the structure of the lipid membrane and polyelectrolyte multilayers, which in turn results in the rapid

  9. Colloidal microcapsules: Surface engineering of nanoparticles for interfacial assembly

    NASA Astrophysics Data System (ADS)

    Patra, Debabrata

    2011-12-01

    Colloidal Microcapsules (MCs), i.e. capsules stabilized by nano-/microparticle shells are highly modular inherently multi-scale constructs with applications in many areas of material and biological sciences e.g. drug delivery, encapsulation and microreactors. These MCs are fabricated by stabilizing emulsions via self-assembly of colloidal micro/nanoparticles at liquid-liquid interface. In these systems, colloidal particles serve as modular building blocks, allowing incorporation of the particle properties into the functional capabilities of the MCs. As an example, nanoparticles (NPs) can serve as appropriate antennae to induce response by external triggers (e.g. magnetic fields or laser) for controlled release of encapsulated materials. Additionally, the dynamic nature of the colloidal assembly at liquid-liquid interfaces result defects free organized nanostructures with unique electronic, magnetic and optical properties which can be tuned by their dimension and cooperative interactions. The physical properties of colloidal microcapsules such as permeability, mechanical strength, and biocompatibility can be precisely controlled through the proper choice of colloids and preparation conditions for their. This thesis illustrates the fabrication of stable and robust MCs through via chemical crosslinking of the surface engineered NPs at oil-water interface. The chemical crosslinking assists NPs to form a stable 2-D network structure at the emulsion interface, imparting robustness to the emulsions. In brief, we developed the strategies for altering the nature of chemical interaction between NPs at the emulsion interface and investigated their role during the self-assembly process. Recently, we have fabricated stable colloidal microcapsule (MCs) using covalent, dative as well as non-covalent interactions and demonstrated their potential applications including encapsulation, size selective release, functional devices and biocatalysts.

  10. Externally triggered dual function of complex microcapsules.

    PubMed

    Yi, Qiangying; Sukhorukov, Gleb B

    2013-10-22

    By introducing UV-sensitive chemical groups causing different potential response as building blocks, fabricated LbL capsules can be endowed with dual UV-responsive properties in specific layers. One block is responsible for fast capsule sealing and the other for longer term capsule swelling and rupture. Therefore, the multifunction of these capsules could be activated selectively when exposed to external UV light with suitable wavelengths. In this work, dual-functional complex microcapsules (PDADMAC/PAZO)4-(DAR/Nafion)2 containing both diazonium and aozbenzene groups were proposed as clear examples to realize a time-dependent UV response for successive encapsulation and release. Upon exposure to UV light, the DAR/Nafion layers underwent a rapid in situ cross-linking and hence to seal the capsule shells through diazonium-related photolysis. Then further gradual shell swelling was followed by realignment of azobenzene molecules in PDADMAC/PAZO layers. Fluorescent polymers were consequently studied as cargo substances. Results indicated that continuous UV light triggered rapid cargo encapsulation over minutes time scale and gradual release with continuous irradiation over hours. PMID:24083649

  11. A New Fluidized Bed Bioreactor Based on Diversion-Type Microcapsule Suspension for Bioartificial Liver Systems

    PubMed Central

    Li, Jianzhou; Yu, Liang; Chen, Ermei; Zhu, Danhua; Zhang, Yimin; Li, LanJuan

    2016-01-01

    A fluidized bed bioreactor containing encapsulated hepatocytes may be a valuable alternative to a hollow fiber bioreactor for achieving the improved mass transfer and scale-up potential necessary for clinical use. However, a conventional fluidized bed bioreactor (FBB) operating under high perfusion velocity is incapable of providing the desired performance due to the resulting damage to cell-containing microcapsules and large void volume. In this study, we developed a novel diversion-type microcapsule-suspension fluidized bed bioreactor (DMFBB). The void volume in the bioreactor and stability of alginate/chitosan microcapsules were investigated under different flow rates. Cell viability, synthesis and metabolism functions, and expression of metabolizing enzymes at transcriptional levels in an encapsulated hepatocyte line (C3A cells) were determined. The void volume was significantly less in the novel bioreactor than in the conventional FBB. In addition, the microcapsules were less damaged in the DMFBB during the fluidization process as reflected by the results for microcapsule retention rates, swelling, and breakage. Encapsulated C3A cells exhibited greater viability and CYP1A2 and CYP3A4 activity in the DMFBB than in the FBB, although the increases in albumin and urea synthesis were less prominent. The transcription levels of several CYP450-related genes and an albumin-related gene were dramatically greater in cells in the DMFBB than in those in the FBB. Taken together, our results suggest that the DMFBB is a promising alternative for the design of a bioartificial liver system based on a fluidized bed bioreactor with encapsulated hepatocytes for treating patients with acute hepatic failure or other severe liver diseases. PMID:26840840

  12. Optimization of technological parameters for preparation of lycopene microcapsules.

    PubMed

    Guo, Hui; Huang, Ying; Qian, Jun-Qing; Gong, Qiu-Yi; Tang, Ying

    2014-07-01

    Lycopene belongs to the carotenoid family with high degree of unsaturation and all-trans form. Lycopene is easy to isomerize and auto oxide by heat, light, oxygen and different food matrices. With an increasing understanding of the health benefit of lycopene, to enhance stability and bioavailability of lycopene, ultrasonic emulsification was used to prepare lycopene microcapsules in this article. The results optimized by response surface methodology (RSM) for microcapsules consisted of four major steps: (1) 0.54 g glycerin monostearate was fully dissolved in 5 mL ethyl acetate and then added 0.02 g lycopene to form an organic phase, 100.7 mL distilled water which dissolved 0.61 g synperonic pe(R)/F68 as the aqueous phase; (2) the organic phase was pulled into the aqueous phase under stirring at 60 °C water bath for 5 min; (3) the mixture was then ultrasonic homogenized at 380 W for 20 min to form a homogenous emulsion; (4) the resulting emulsion was rotary evaporated at 50 °C water bath for 10 min under a pressure of 20 MPa. Encapsulation efficiency (EE) of lycopene microcapsules under the optimized conditions approached to 64.4%. PMID:24966425

  13. Investigation of UV photocurable microcapsule inner crosslink extent

    NASA Astrophysics Data System (ADS)

    Li, Xiaowei; Meng, Shuangshuang; Lai, Weidong; Yu, Haiyang; Fu, Guangsheng

    2008-11-01

    UV photocuring technology has encountered increased applications in recent years, which finds a variety of applications on protective coating of the optical-fiber, ink and optical recording materials. Combined with techniques of photohardenable, microcapsule, heat-sensitive and interface-polymerization method, a novel photoheat sensitive recording material of non-silver salt is explored in this thesis. Microcapsules are particulate substance with a core and shell structure, where photopolymerizable composition, monofunctional/polyfunctional diluents, photopolymerization initiator, photosensitivity enhancing agent and dye precursor are encapsulated as the internal phase. In this paper introduced the characteristics and curing mechanism of photo-sensitive microcapsule materials. The photocuring process may be a complex-function with photopolymerizable compound and photopolymerization initiator. For the sake of high photocuring speed and degree, optimal photo-sensitive materials were selected. In order to match with the light source excitation wavelength and absorb more wider ultraviolet band, combined type of photo-polymerization initiators were employed. With the kinds and dosage of photopolymerization initiator changing, the photocuring speed and quality can be ameliorated. Through studying the UV-visible absorption spectrum and infra-red spectrum of the material , the optical response property of the inner compound can be obtained.

  14. Ultrathin antibiotic walled microcapsules.

    PubMed

    Khopade, Ajay J; Arulsudar, N; Khopade, Surekha A; Hartmann, J

    2005-01-01

    Ultrathin microcapsules comprised of anionic polyelectrolytes (PE) and a polycationic aminoglycoside (AmG) antibiotic drug were prepared by depositing PE/AmG multilayers on zinc oxide (ZnO) colloid particles using the layer-by-layer self-assembly technique and subsequently dissolving the ZnO templated cores. The polyelectrolytes, dextran sulfate sodium (DxS) and poly(styrenesulfonate) (PSS), were selected owing to their different backbone structure. An aminoglycoside, tobramycin sulfate (TbS), was used for studying DxS/TbS or PSS/TbS multilayer films. The multilayer growth on ZnO cores was characterized by alternating zeta potential values that were different for the DxS/TbS and PSS/TbS multilayers due to the PE chemistry and its interaction with Zn(2+) ions. Transmission and scanning electron microscopy provide evidence of PE/TbS multilayer coating on ZnO core particles. The slow acid-decomposition of the ZnO cores using weak organic acids and the presence of sufficient quantity of Zn(2+) in the dispersion were required to produce antibiotic multilayer capsules. There was no difference in the morphological characteristics of the two types of capsules; although, the yield for [PSS/TbS](5) capsules was significantly higher than for [DxS/TbS](5) capsules which was related to the physicochemical properties of DxS/TbS/Zn(2+) and PSS/TbS/Zn(2+) complexes forming the capsule wall. The TbS quantity in the multilayer films was determined using a quartz crystal microbalance and high performance liquid chromatography techniques which showed less TbS loading in both, capsules and multilayers on planar gold substrate, than the theoretical DxS:TbS or PSS:TbS stoichiometric ratio. The decomposition of the [PE/TbS](6) multilayers was fastest in physiological buffer followed by mannitol and water. The decomposition rate of the [PSS/TbS](6) multilayers was slower than [DxS/TbS](6) monolayers. The incomplete decomposition of DxS/TbS under saline conditions suggests the major role of

  15. Development and characterization of hollow polymeric microcapsules for use as contrast agents for diagnostic ultrasound

    NASA Astrophysics Data System (ADS)

    Narayan, Padma Jyothi

    1999-09-01

    This thesis concerns the development and characterization of a new type of rigid-shelled ultrasound contrast agent. A novel method was devised for producing hollow, gas- filled, polymer microcapsules, sized to less than 10 μm in diameter for contrast imaging. This method involved the encapsulation of a solid, volatile core material, and its subsequent evacuation by sublimation. The biodegradable polymer, 50/50 poly(D,L-lactide-co- glycolide), was the main focus of this study. Polymer- based contrast agents have many advantages, such as their applicability for concomitant imaging and drug delivery. Three encapsulation techniques were evaluated: solvent evaporation, coacervation, and spray drying. The polymer molecular weight and polydispersity in the solvent evaporation and coacervation techniques strongly affected microcapsule size and morphology. Efficient mechanical agitation and shear were crucial for obtaining high yields in the desired size range (less than 6 μm). In spray drying, a factorial design approach was used to optimize conditions to produce microcapsules. The main factors affecting spray drying were found to be the temperature driving force for drying and initial polymer concentration. The smallest microcapsule mean diameters were produced by spray drying (3-4 μm) and solvent evaporation (5-6 μm). Zeta potential (ζ) studies for all microcapsule types indicated that the encapsulation technique affected their surface properties due to the orientation of the polymer chains within nascent polymer droplets. Microcapsules with the most hydrophilic tendency were produced with solvent evaporation (ζ ~ -50 mV). In vitro acoustic testing revealed that the 20-41 μm size fractions of coacervate microcapsules were the most echogenic. In vivo ultrasound studies with both solvent evaporation and coacervate microcapsules showed visible enhancement of the color Doppler image in the rabbit kidney for the samples less than 10 μm in diameter. A mathematical

  16. pH-sensitive poly(lactide-co-glycolide) nanoparticle composite microcapsules for oral delivery of insulin

    PubMed Central

    Sun, Shaoping; Liang, Na; Yamamoto, Hiromitsu; Kawashima, Yoshiaki; Cui, Fude; Yan, Pengfei

    2015-01-01

    This study proposes a new concept of pH-sensitive poly(lactide-co-glycolide) (PLGA) nanoparticle composite microcapsules for oral delivery of insulin. Firstly, insulin–sodium oleate complex was prepared by the hydrophobic ion pairing method and then encapsulated into PLGA nanoparticles by the emulsion solvent diffusion method. In order to reduce the burst release of insulin from PLGA nanoparticles and deliver insulin to specific gastrointestinal regions, hence to enhance bioavailability of insulin, the PLGA nanoparticles were further encapsulated into Eudragit® FS 30D to prepare PLGA nanoparticle composite microcapsules by organic spray-drying method. The preparation was evaluated in vitro and in vivo, and the absorption mechanism was discussed. The in vitro drug release studies revealed that the drug release was pH dependent, and the in vivo results demonstrated that the formulation of PLGA nanoparticle composite microcapsules was an effective candidate for oral insulin delivery. PMID:25999713

  17. Preparation of robust polyamide microcapsules by interfacial polycondensation of p-phenylenediamine and sebacoyl chloride and plasticization with oleic acid.

    PubMed

    Rosa, Natacha; Martins, Gabriela V; Bastos, Margarida M S M; Gois, Joana R; Coelho, Jorge F J; Marques, Juliana; Tavares, Carlos J; Magalhães, Fernão D

    2015-01-01

    Microcapsules produced by interfacial polycondensation of p-phenylenediamine (PPD) and sebacoyl chloride (SC) were studied. The products were characterized in terms of morphology, mean diameter and effectiveness of dodecane encapsulation. The use of Tween 20 as dispersion stabilizer, in comparison with polyvinyl alcohol (PVA), reduced considerably the mean diameter of the microcapsules and originated smoother wall surfaces. When compared to ethylenediamine (EDA), microcapsules produced with PPD monomer were more rigid and brittle, prone to fracture during processing and ineffective retention of the core liquid. The use of diethylenetriamine (DETA) cross-linker in combination with PPD did not decrease capsule fragility. On the other hand, addition of a small fraction of oleic acid to the organic phase remarkably improved wall toughness and lead to successful encapsulation of the core-oil. Oleic acid is believed to act as a plasticizer. Its incorporation in the polymeric wall was demonstrated by FTIR and (1)H-NMR. PMID:26052719

  18. Halogenation of microcapsule walls

    NASA Technical Reports Server (NTRS)

    Davis, T. R.; Schaab, C. K.; Scott, J. C.

    1972-01-01

    Procedure for halogenation of confining walls of both gelatin and gelatin-phenolic resin capsules is similar to that used for microencapsulation. Ten percent halogen content renders capsule wall nonburning; any higher content enhances flame-retardant properties of selected internal phase material. Halogenation decreases permeability of wall material to encapsulated materials.

  19. Production of BCG alginate-PLL microcapsules by emulsification/internal gelation.

    PubMed

    Esquisabel, A; Hernández, R M; Igartua, M; Gascón, A R; Calvo, B; Pedraz, J L

    1997-01-01

    A biocompatible emulsification method for microencapsulation of live cells and enzymes within a calcium alginate matrix applied to Bacillus Calmette-Guérin (BCG) has been developed. Small-diameter alginate beads (microcapsules) were formed via internal gelation of an alginate solution emulsified within vegetable oil. Five different oils (sesame, sweet almond, perhydrosqualene, camomile and jojoba) were used. The rheological analysis of the oils showed a Newtonian behaviour, with viscosities = 30.0, 37.7, 51.2, 59.3 and 67.1 mPa.s for perhydrosqualene, jojoba, camomile, sesame and sweet almond oil respectively. The particle size of the microcapsules obtained ranged from 30.3 microns for the microcapsules prepared with sweet almond oil to 57.0 microns for those made with perhydrosqualene. The mean particle diameter obtained was found to be dependent on the viscosity of the oil employed, according to the equation: phi (micron) = 76.6-0.628 eta (mPa.s) (r2 = 0.943). The encapsulated BCG was identified by the Difco TB stain set K, followed by observation under optical microscopy. Freeze-drying of the microcapsules was carried out to ensure their stability during storage. Two batches of microcapsules (those prepared with sesame and jojoba oil) and four types of cryoprotectors (glucose, trehalose, mannitol and sorbitol), at three concentration levels (5, 10 and 20% w/v) were studied. The parameters evaluated were particle size, physical appearance, reconstitution of lyophilizates and microscopical evaluation. For both batches of microcapsules the best results were obtained with trehalose 5%, showing particle sizes of 42.1 microns in the case of the microcapsules prepared with sesame oil, and of 45.3 microns for those prepared with jojoba. PMID:9292438

  20. Preparation of insulin-loaded PLA/PLGA microcapsules by a novel membrane emulsification method and its release in vitro.

    PubMed

    Liu, Rong; Huang, Shan-Shan; Wan, Yin-Hua; Ma, Guang-Hui; Su, Zhi-Guo

    2006-08-01

    Uniform-sized biodegradable PLA/PLGA microcapsules loading recombinant human insulin (rhI) were successfully prepared by combining a Shirasu Porous Glass (SPG) membrane emulsification technique and a double emulsion-evaporation method. An aqueous phase containing rhI was used as the inner water phase (w1), and PLA/PLGA and Arlacel 83 were dissolved in a mixture solvent of dichloromethane (DCM) and toluene, which was used as the oil phase (o). These two solutions were emulsified by a homogenizer to form a w1/o primary emulsion. The primary emulsion was permeated through the uniform pores of a SPG membrane into an outer water phase by the pressure of nitrogen gas to form the uniform w1/o/w2 droplets. The solid polymer microcapsules were obtained by simply evaporating solvent from droplets. Various factors of the preparation process influencing the drug encapsulation efficiency and the drug cumulative release were investigated systemically. The results indicated that the drug encapsulation efficiency and the cumulative release were affected by the PLA/PLGA ratio, NaCl concentration in outer water phase, the inner water phase volume, rhI-loading amount, pH-value in outer water phase and the size of microcapsules. By optimizing the preparation process, the drug encapsulation efficiency was high up to 91.82%. The unique advantage of preparing drug-loaded microcapsules by membrane emulsification technique is that the size of microcapsules can be controlled accurately, and thus the drug cumulative release profile can be adjusted just by changing the size of microcapsules. Moreover, much higher encapsulation efficiency can be obtained when compared with the conventional mechanical stirring method. PMID:16814994

  1. Development of melamine-formaldehyde resin microcapsules with low formaldehyde emission suited for seed treatment.

    PubMed

    Yuan, Huizhu; Li, Guangxing; Yang, Lijuan; Yan, Xiaojing; Yang, Daibin

    2015-04-01

    To reduce the application frequency and improve the efficacy of insecticides, melamine-formaldehyde (MF) resin microcapsules suited for seed treatment containing a mixture of fipronil and chlorpyrifos were prepared by in situ polymerization. A formaldehyde/melamine molar ratio of 4:1 yielded microcapsules with the smallest size and the most narrow size distribution. The level of unreacted formaldehyde in the microcapsule suspension increased proportionally with the F/M molar ratio. When the MF resin microcapsule suspension was used as a seed treatment to coat peanut seeds, the unreacted formaldehyde did not significantly inhibit the seedling emergence, but the ongoing release of formaldehyde generated from the degradation of MF resins played an important role in inhibiting emergence. Melamine was shown to be an effective formaldehyde scavenger that mitigated this inhibition when it was incorporated within the microcapsule wall. Field experiments showed that MF-resin-encapsulated mixtures of fipronil and chlorpyrifos have much greater efficacies against white grubs than the conventional formulation. PMID:25734968

  2. Responsive hybrid microcapsules by the one-step interfacial thiol-ene photopolymerization.

    PubMed

    Liu, Dandan; Yu, Bing; Jiang, Xuesong; Yin, Jie

    2013-04-30

    We here demonstrated a general, convenient, and robust method to fabricate the hybrid microcapsules through the one-step thiol-ene photopolymerization at the interface between toluene and water. In the presence of amphiphilic polyhedral oligomeric silsesquioxane (POSS) containing thiol groups (PTPS) as reactive surfactants and trimethylolpropane triacrylate (TMPTA) as a cross-linker, the wall of hybrid microcapsules can be photo-cross-linked. The obtained hybrid microcapsules (HMCs) were well-characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), atomic force microscopy (AFM), and confocal laser scanning microscopy (CLSM). The results revealed that the obtained HMCs are uniform with the tunable size in diameter (2-4 μm) and wall thickness (55-120 nm). The size of HMCs increased with the increasing content of toluene. The wall thickness of HMCs decreased with the increasing content of toluene, while the wall thickness of HMCs increased with the increasing content of cross-linker TMPTA. Furthermore, HMCs are thermoresponsive in aqueous solution, can encapsulate both hydrophobic and dydrophilic dyes, and can be used in the controlled dispersion of dyes in different mediums. It is believed that this simple, robust, and general method to fabricate the hybrid microcapsules will extend the potential application fields of microcapsules, such as in the controlled dispersion and drug delivery. PMID:23547914

  3. Highly Stable and Conductive Microcapsules for Enhancement of Joule Heating Performance.

    PubMed

    Zheng, Zhaoliang; Jin, Jidong; Xu, Guang-Kui; Zou, Jianli; Wais, Ulrike; Beckett, Alison; Heil, Tobias; Higgins, Sean; Guan, Lunhui; Wang, Ying; Shchukin, Dmitry

    2016-04-26

    Nanocarbons show great promise for establishing the next generation of Joule heating systems, but suffer from the limited maximum temperature due to precociously convective heat dissipation from electrothermal system to surrounding environment. Here we introduce a strategy to eliminate such convective heat transfer by inserting highly stable and conductive microcapsules into the electrothermal structures. The microcapsule is composed of encapsulated long-chain alkanes and graphene oxide/carbon nanotube hybrids as core and shell material, respectively. Multiform carbon nanotubes in the microspheres stabilize the capsule shell to resist volume-change-induced rupture during repeated heating/cooling process, and meanwhile enhance the thermal conductance of encapsulated alkanes which facilitates an expeditious heat exchange. The resulting microcapsules can be homogeneously incorporated in the nanocarbon-based electrothermal structures. At a dopant of 5%, the working temperature can be enhanced by 30% even at a low voltage and moderate temperature, which indicates a great value in daily household applications. Therefore, the stable and conductive microcapsule may serve as a versatile and valuable dopant for varieties of heat generation systems. PMID:27002594

  4. Multi-Drug-Loaded Microcapsules with Controlled Release for Management of Parkinson's Disease.

    PubMed

    Baek, Jong-Suep; Choo, Chee Chong; Qian, Cheng; Tan, Nguan Soon; Shen, Zexiang; Loo, Say Chye Joachim

    2016-07-01

    Parkinson's disease (PD) is a progressive disease of the nervous system, and is currently managed through commercial tablets that do not sufficiently enable controlled, sustained release capabilities. It is hypothesized that a drug delivery system that provides controlled and sustained release of PD drugs would afford better management of PD. Hollow microcapsules composed of poly-l-lactide (PLLA) and poly (caprolactone) (PCL) are prepared through a modified double-emulsion technique. They are loaded with three PD drugs, i.e., levodopa (LD), carbidopa (CD), and entacapone (ENT), at a ratio of 4:1:8, similar to commercial PD tablets. LD and CD are localized in both the hollow cavity and PLLA/PCL shell, while ENT is localized in the PLLA/PCL shell. Release kinetics of hydrophobic ENT is observed to be relatively slow as compared to the other hydrophilic drugs. It is further hypothesized that encapsulating ENT into PCL as a surface coating onto these microcapsules can aid in accelerating its release. Now, these spray-coated hollow microcapsules exhibit similar release kinetics, according to Higuchi's rate, for all three drugs. The results suggest that multiple drug encapsulation of LD, CD, and ENT in gastric floating microcapsules could be further developed for in vivo evaluation for the management of PD. PMID:27253884

  5. Dynamics and stability of dispersions of polyelectrolyte-filled multilayer microcapsules.

    PubMed

    Kim, Byoung-Suhk; Lobaskin, Vladimir; Tsekov, Roumen; Vinogradova, Olga I

    2007-06-28

    The authors report dynamic and coagulation properties of a dispersion of polyelectrolyte multilayer microcapsules filled with solutions of a strong polyelectrolyte. Microcapsules are shown to take a charge of the sign of encapsulated polyions and are characterized by a nonuniform distribution of inner polyions, which indicates a semipermeability of the shell and a leakage of counterions. The capsule self-diffusion coefficient in the vicinity of the similarly charged wall is measured using a particle tracking procedure from confocal images of the dispersion. The diffusion of capsules in the force field suggests that the effective interaction potential contains an electrostatic barrier, so that we deal with the same types of interaction forces as for solid particles. The theoretical estimates of the authors show that when microcapsules are in close proximity, their interaction should even be quantitatively the same as that of colloids with the same surface potential. However, due to the mobility of inner polyions they might repel stronger at large distances. The authors thus conclude that the encapsulation of charged polymers is an important factor in determining the adhesion and interaction properties of multilayer microcapsules. PMID:17614584

  6. Highly Stable and Conductive Microcapsules for Enhancement of Joule Heating Performance

    PubMed Central

    2016-01-01

    Nanocarbons show great promise for establishing the next generation of Joule heating systems, but suffer from the limited maximum temperature due to precociously convective heat dissipation from electrothermal system to surrounding environment. Here we introduce a strategy to eliminate such convective heat transfer by inserting highly stable and conductive microcapsules into the electrothermal structures. The microcapsule is composed of encapsulated long-chain alkanes and graphene oxide/carbon nanotube hybrids as core and shell material, respectively. Multiform carbon nanotubes in the microspheres stabilize the capsule shell to resist volume-change-induced rupture during repeated heating/cooling process, and meanwhile enhance the thermal conductance of encapsulated alkanes which facilitates an expeditious heat exchange. The resulting microcapsules can be homogeneously incorporated in the nanocarbon-based electrothermal structures. At a dopant of 5%, the working temperature can be enhanced by 30% even at a low voltage and moderate temperature, which indicates a great value in daily household applications. Therefore, the stable and conductive microcapsule may serve as a versatile and valuable dopant for varieties of heat generation systems. PMID:27002594

  7. Long-term insulinotropic activity of glucagon-like peptide-1/polymer conjugate on islet microcapsules.

    PubMed

    Kim, Sungwon; Bae, You Han

    2004-01-01

    The biohybrid artificial pancreas (BAP), a promising therapy for type 1 diabetes, faces several obstacles such as the need for a large implantation volume of encapsulated islets because of low functionality. To address such problems, in this study we examined long-term insulinotropic activity of glucagon-like peptide-1 (GLP-1)/polymer conjugate [VAPG: poly(N-vinylpyrrolidone-co-acrylic acid-g-PEG) (VAP)-GLP-1] as well as GLP-1/Zn(2+) crystal by coencapsulation with islets. Microcapsules with VAPG or crystal produced round-shaped beads whereas free GLP-1 showed poor capsule morphology. A perfusion experiment suggested that VAPG showed higher bioactivity than did microcapsules with GLP-1/Zn(2+). In long-term culture (200 mg of glucose/dL [G]), VAPG also enhanced insulinotropic activity over 5 weeks compared with the crystal form of GLP-1. However, maintenance of the high bioactivity of VAPG suddenly declined after week 5, possibly because of degradation, metabolism, and overstimulation. Basal (50 G) and glucose-stimulated (300 G) levels of insulin secretion confirmed a see-saw pattern in which the VAPG gradually decreased insulin secretion from encapsulated islets and then fell below the insulin level secreted from microcapsules containing GLP-1/Zn(2+) crystal. Viability of the microcapsulated islets of each group was not significantly different. Consequently, the coencapsulation of VAPG or GLP-1/Zn(2+) crystal can be a potential approach to reducing BAP volume with further optimization of activity duration. PMID:15684669

  8. Encapsulation of volatiles by homogenized partially-cross linked alginates.

    PubMed

    Inguva, Pavan K; Ooi, Shing Ming; Desai, Parind M; Heng, Paul W S

    2015-12-30

    Cross-linked calcium alginate gels are too viscous to be efficaciously incorporated into spray dried formulations. Thus, viscosity reduction is essential to ensure the processability of calcium alginate gels to be sprayed. Viscosity reduction by high pressure homogenization can open new formulation possibilities. Presently, testing of microcapsule integrity is also limited because either single particle tests neglect collective particle behaviours in bulk or bulk testing methods are often associated with single compressions which may not fully characterize individual particle strengths. The aim of this study was sub-divided into three objectives. First objective was to evaluate the impact of high pressure homogenization on gel viscosity. Second objective was to explore the use of the homogenized gels with modified starch for microencapsulation by spray drying. The final objective was to develop a stamping system as microcapsule strength tester that can assess microcapsules in bulk and evaluate the impact of multiple compressions. Collectively, this study would lead towards developing a pressure-activated patch of microcapsules with encapsulated volatiles and the method to assess the patch efficacy. The alginate gels largely experienced an exponential decay in viscosity when homogenized. Furthermore, the homogenized gels were successfully incorporated in spray drying formulations for microencapsulation. The custom-designed microcapsule strength tester was successfully used and shown to possess the required sensitivity to discern batches of microcapsules containing volatiles to have different release profiles. Addition of homogenized gels strengthened the microcapsules only at high wall to core ratios with low mass-load alginate gels. High mass-load gels weaken the microcapsules, exhibiting a higher release at low stamping pressures and wrinkling on the microcapsules surface. PMID:26581772

  9. Characterization of Raoultella planticola Rs-2 microcapsule prepared with a blend of alginate and starch and its release behavior.

    PubMed

    Wu, Zhansheng; He, Yanhui; Chen, Lijun; Han, Yajie; Li, Chun

    2014-09-22

    To judiciously use Raoultella planticola Rs-2 and develop its biodegradable and controlled-release formulations, Rs-2 was encapsulated with various combinations of sodium alginate (NaAlg) and starch. Sodium alginate, soluble starch, and CaCl2 showed good biocompatibility with Rs-2 for preparing microcapsules. These microcapsules were spherical in shape and their particle size, embedding rate, swelling ratio of Rs-2 microcapsules and release numbers of viable Rs-2 cells increased with the increasing of starch and NaAlg concentrations. Meanwhile, the biodegradability of the microcapsules constantly increases when the wt% of starch increased, but decreased when the amount of NaAlg increased. In addition, the release mechanism of microcapsules was consistent with that of the Ritger-Peppas model, which involves the Case II diffusion mechanism. In summary, the desired properties of the microcapsules can be modulated by varying the starch and alginate amounts of capsule materials. This process has broad application prospects to meet the needs of agricultural production. PMID:24906754

  10. Preparation of high thermal stability polysulfone microcapsules containing lubricant oil and its tribological properties of epoxy composites.

    PubMed

    Li, Haiyan; Wang, Qing; Li, Meiling; Cui, Yexiang; Zhu, Yanji; Wang, Baohui; Wang, Huaiyuan

    2016-05-01

    Polysulfone (PSF) microcapsules containing lubricant oil have been successfully prepared using solvent evaporation method. The results show that lubricant oil was successfully encapsulated and the encapsulation capacity of about 56.0 wt.% was achieved. The uniform microcapsules have nearly spherical shape and quite smooth outer surface. The mean diameter is approximately 156 and 169 μm by using different dispersant solutions. The wall material is porous in structure with wall thickness of about 20 μm. The initial decomposition temperature of PSF is 480 °C. It is higher than traditional poly(urea-formaldehyde) (PUF) and poly(melamine-formaldehyde) (PMF) wall materials with 245 °C and 260 °C initial decomposition temperature, respectively. High thermal stability of PSF microcapsules can be considered as additives in high temperature resistant polymer materials. The frictional coefficient and wear rate of epoxy composites decreased significantly by incorporating microcapsules containing lubricant oil into epoxy. When the concentration of microcapsules was 25 wt.%, the frictional coefficient and specific wear rate were reduced by 2.3 and 18.3 times, respectively, as compared to the neat epoxy. PMID:27066695

  11. Improved stability and controlled release of CLA with spray-dried microcapsules of OSA-modified starch and xanthan gum.

    PubMed

    He, Huizi; Hong, Yan; Gu, Zhengbiao; Liu, Guodong; Cheng, Li; Li, Zhaofeng

    2016-08-20

    The objective of this investigation was to improve the stability of CLA and to allow for its controlled release by encapsulating it with combinations of octenyl-succinic anhydride (OSA) starch and xanthan gum (XG) in three ratios (OSA/XG: 60/1, 80/1, and 100/1, w/w). The wall material was examined using FTIR and TGA. The microcapsules were characterized by laser particle size analysis (LPS) and SEM. Oxidation of the microcapsules was monitored by headspace method. The results revealed that microcapsules created with an OSA/XG ratio of 60/1 provided superior protection to CLA against oxidation. When CLA-microcapsules were subjected to conditions simulating those in the human gastrointestinal system, 12.1%-50.1% of the CLA was released. CLA encapsulation in spray-dried microcapsules of OSA/XG appears to be an effective technique that provides good protection against oxidation and could be useful in the targeted delivery of functional lipids or other bioactive components to the small intestine. PMID:27178930

  12. Long-Term Retention of Small, Volatile Molecular Species within Metallic Microcapsules.

    PubMed

    Hitchcock, James P; Tasker, Alison L; Baxter, Elaine A; Biggs, Simon; Cayre, Olivier J

    2015-07-15

    Encapsulation and full retention of small molecular weight active ingredients is a challenging task that remains unsolved by current technologies used in industry and academia. In particular, certain everyday product formulations provide difficult environments in which preventing active leakage through capsule walls is not feasible. For example, a continuous phase that can fully dissolve an encapsulated active will typically force full release over a fraction of the intended lifetime of a product. This is due to the inherent porosity of polymeric membranes typically used as capsule wall material in current technologies. In this study, we demonstrate a method for preventing undesired loss of encapsulated actives under these extreme conditions using a simple threestep process. Our developed methodology, which forms an impermeable metal film around polymer microcapsules, prevents loss of small, volatile oils within an ethanol continuous phase for at least 21 days while polymeric capsules lose their entire content in less than 30 min under the same conditions. Polymer shell-oil core microcapsules are produced using a well-known cosolvent extraction method to precipitate a polymeric shell around the oil core. Subsequently, metallic catalytic nanoparticles are physically adsorbed onto the microcapsule polymeric shells. Finally, this nanoparticle coating is used to catalyze the growth of a secondary metallic film. Specifically, this work shows that it is possible to coat polymeric microcapsules containing a model oil system or a typical fragrance oil with a continuous metal shell. It also shows that the coverage of nanoparticles on the capsule surface can be controlled, which is paramount for obtaining a continuous impermeable metal film. In addition, control over the metal shell thickness is demonstrated without altering the capability of the metal film to retain the encapsulated oils. PMID:26079485

  13. Pulsatile protein release from monodisperse liquid-core microcapsules of controllable shell thickness

    PubMed Central

    Xia, Yujie; Pack, Daniel W.

    2014-01-01

    Purpose Pulsatile delivery of proteins, in which release occurs over a short time after a period of little or no release, is desirable for many applications. This paper investigates the effect of biodegradable polymer shell thickness on pulsatile protein release from biodegradable polymer microcapsules. Methods Using precision particle fabrication (PPF) technology, monodisperse microcapsules were fabricated encapsulating bovine serum albumin (BSA) in a liquid core surrounded by a drug-free poly(lactide-co-glycolide) (PLG) shell of uniform, controlled thickness from 14 to 19 μm. Results When using high molecular weight PLG (Mw 88 kDa), microparticles exhibited the desired core-shell structure with high BSA loading and encapsulation efficiency (55-65%). These particles exhibited very slow release of BSA for several weeks followed by rapid release of 80-90% of the encapsulated BSA within seven days. Importantly, with increasing shell thickness the starting time of the pulsatile release could be controlled from 25 to 35 days. Conclusions Biodegradable polymer microcapsules with precisely controlled shell thickness provide pulsatile release with enhanced control of release profiles. PMID:24831313

  14. In situ growth of fluorescent silicon nanocrystals in a monolithic microcapsule as a photostable, versatile platform.

    PubMed

    Zhu, Guixian; Huang, Yu; Bhave, Gauri; Wang, Yuzhen; Hu, Zhongbo; Liu, Xuewu

    2016-08-25

    A facile, one-step method was developed for the in situ formation of fluorescent silicon nanocrystals (SiNC) in a microspherical encapsulating matrix. The obtained SiNC encapsulated polymeric microcapsules (SiPM) possess uniform size (0.1-2.0 μm), strong fluorescence, and nanoporous structure. A unique two stage, time dependent reaction was developed, as the growth of SiNC was slower than the formation of polymeric microcapsules. The resulting SiPM with increasing reaction time exhibited two levels of stability, and correspondingly, the release of SiNC in aqueous media showed different behavior. With reaction time <1 h, the obtained low-density SiPM (LD-SiPM) as matrix microcapsules, would release encapsulated SiNC on demand. With >1 h reaction time, resulting high-density SiPM (HD-SiPM) became stable SiNC reservoirs. SiPM exhibit stable photoluminescence. The porous structure and fluorescence quenching effects make SiPM suitable for bioimaging, drug loading and sorption of heavy metals (Hg(2+) as shown) as an intrinsic indicator. SiPM were able to reduce metal ions, forming SiPM/metal oxide and SiPM/metal hybrids, and their applications in bio-sensing and catalysis were also demonstrated. PMID:27515701

  15. Membrane emulsification to produce perfume microcapsules

    NASA Astrophysics Data System (ADS)

    Pan, Xuemiao

    Microencapsulation is an efficient technology to deliver perfume oils from consumer products onto the surface of fabrics. Microcapsules having uniform size/mechanical strength, may provide better release performance. Membrane emulsification in a dispersion cell followed by in-situ polymerization was used to prepare narrow size distribution melamine-formaldehyde (MF) microcapsules containing several types of oil-based fragrances or ingredients. Investigated in this study are the parameters impacting to the size and size distribution of the droplets and final MF microcapsules. A pilot plant-scale cross-flow membrane system was also used to produce MF microcapsules, demonstrating that the membrane emulsification process has potential to be scaled up for industrial applications. In this study, health and environmental friendly poly (methyl methacrylate) (PMMA) microcapsules with narrow size distribution were also prepared for the first time using the dispersion cell membrane emulsification system. Characterization methods previously used for thin-shell microcapsules were expanded to analyse microcapsules with thick shells. The intrinsic mechanical properties of thick shells were determined using a micromanipulation technique and finite element analysis (FEM). The microcapsules structure was also considered in the determination of the permeability and diffusivity of the perfume oils in good solvents..

  16. Gelatin microcapsules for enhanced microwave tumor hyperthermia.

    PubMed

    Du, Qijun; Fu, Changhui; Tie, Jian; Liu, Tianlong; Li, Linlin; Ren, Xiangling; Huang, Zhongbing; Liu, Huiyu; Tang, Fangqiong; Li, Li; Meng, Xianwei

    2015-02-21

    Local and rapid heating by microwave (MW) irradiation is important in the clinical treatment of tumors using hyperthermia. We report here a new thermo-seed technique for the highly efficient MW irradiation ablation of tumors in vivo based on gelatin microcapsules. We achieved 100% tumor elimination in a mouse model at an ultralow power of 1.8 W without any side-effects. The results of MTT assays, a hemolysis test and the histological staining of organs indicated that the gelatin microcapsules showed excellent compatibility with the physiological environment. A possible mechanism is proposed for MW hyperthermia using gelatin microcapsules. We also used gelatin microcapsules capped with CdTe quantum dots for in vivo optical imaging. Our study suggests that these microcapsules may have potential applications in imaging-guided cancer treatment. PMID:25613756

  17. Reconfigurable antenna pattern verification

    NASA Technical Reports Server (NTRS)

    Drexler, Jerome P. (Inventor); Becker, Robert C. (Inventor); Meyers, David W. (Inventor); Muldoon, Kelly P. (Inventor)

    2013-01-01

    A method of verifying programmable antenna configurations is disclosed. The method comprises selecting a desired antenna configuration from a plurality of antenna configuration patterns, with the selected antenna configuration forming at least one reconfigurable antenna from reconfigurable antenna array elements. The method validates the formation of the selected antenna configuration to determine antenna performance of the at least one reconfigurable antenna.

  18. A review of the preparation and application of flavour and essential oils microcapsules based on complex coacervation technology.

    PubMed

    Xiao, Zuobing; Liu, Wanlong; Zhu, Guangyong; Zhou, Rujun; Niu, Yunwei

    2014-06-01

    This paper briefly introduces the preparation and application of flavour and essential oils microcapsules based on complex coacervation technology. The conventional encapsulating agents of oppositely charged proteins and polysaccharides that are used for microencapsulation of flavours and essential oils are reviewed along with the recent advances in complex coacervation methods. Proteins extracted from animal-derived products (gelatin, whey proteins, silk fibroin) and from vegetables (soy proteins, pea proteins), and polysaccharides such as gum Arabic, pectin, chitosan, agar, alginate, carrageenan and sodium carboxymethyl cellulose are described in depth. In recent decades, flavour and essential oils microcapsules have found numerous potential practical applications in food, textiles, agriculturals and pharmaceuticals. In this paper, the different coating materials and their application are discussed in detail. Consequently, the information obtained allows criteria to be established for selecting a method for the preparation of microcapsules according to their advantages, limitations and behaviours as carriers of flavours and essential oils. PMID:24282124

  19. Modulating drug release from gastric-floating microcapsules through spray-coating layers.

    PubMed

    Lee, Wei Li; Tan, Jun Wei Melvin; Tan, Chaoyang Nicholas; Loo, Say Chye Joachim

    2014-01-01

    Floating dosage forms with prolonged gastric residence time have garnered much interest in the field of oral delivery. However, studies had shown that slow and incomplete release of hydrophobic drugs during gastric residence period would reduce drug absorption and cause drug wastage. Herein, a spray-coated floating microcapsule system was developed to encapsulate fenofibrate and piroxicam, as model hydrophobic drugs, into the coating layers with the aim of enhancing and tuning drug release rates. Incorporating fenofibrate into rubbery poly(caprolactone) (PCL) coating layer resulted in a complete and sustained release for up to 8 h, with outermost non-drug-holding PCL coating layer serving as a rate-controlling membrane. To realize a multidrug-loaded system, both hydrophilic metformin HCl and hydrophobic fenofibrate were simultaneously incorporated into these spray-coated microcapsules, with metformin HCl and fenofibrate localized within the hollow cavity of the capsule and coating layer, respectively. Both drugs were observed to be completely released from these coated microcapsules in a sustained manner. Through specific tailoring of coating polymers and their configurations, piroxicam loaded in both the outer polyethylene glycol and inner PCL coating layers was released in a double-profile manner (i.e. an immediate burst release as the loading dose, followed by a sustained release as the maintenance dose). The fabricated microcapsules exhibited excellent buoyancy in simulated gastric fluid, and provided controlled and sustained release, thus revealing its potential as a rate-controlled oral drug delivery system. PMID:25470374

  20. Nanoparticle/Polymer assembled microcapsules with pH sensing property.

    PubMed

    Zhang, Pan; Song, Xiaoxue; Tong, Weijun; Gao, Changyou

    2014-10-01

    The dual-labeled microcapsules via nanoparticle/polymer assembly based on polyamine-salt aggregates can be fabricated for the ratiometric intracellular pH sensing. After deposition of SiO2 nanoparticles on the poly(allylamine hydrochloride)/multivalent anionic salt aggregates followed by silicic acid treatment, the generated microcapsules are stable in a wide pH range (3.0 ∼ 8.0). pH sensitive dye and pH insensitive dye are simultaneously labeled on the capsules, which enable the ratiometric pH sensing. Due to the rough and positively charged surface, the microcapsules can be internalized by several kinds of cells naturally. Real-time measurement of intracellular pH in several living cells shows that the capsules are all located in acidic organelles after being taken up. Furthermore, the negatively charged DNA and dyes can be easily encapsulated into the capsules via charge interaction. The microcapsules with combination of localized pH sensing and drug loading abilities have many advantages, such as following the real-time transportation and processing of the carriers in cells. PMID:25081194

  1. Laser-induced fast fusion of gold nanoparticle-modified polyelectrolyte microcapsules.

    PubMed

    Wu, Yingjie; Frueh, Johannes; Si, Tieyan; Möhwald, Helmuth; He, Qiang

    2015-02-01

    In this study we investigated the effect of laser-induced membrane fusion of polyelectrolyte multilayer (PEM) based microcapsules bearing surface-attached gold nanoparticles (AuNPs) in aqueous media. We demonstrate that a dense coating of the capsules with AuNPs leads to enhanced light absorption, causing an increase of local temperature. This enhances the migration of polyelectrolytes within the PEMs and thus enables a complete fusion of two or more capsules. The encapsulated substances can achieve complete merging upon short-term laser irradiation (30 s, 30 mW @ 650 nm). The whole fusion process is followed by optical microscopy and scanning electron microscopy. In control experiments, microcapsules without AuNPs do not show a significant capsule fusion upon irradiation. It was also found that the duration of capsule fusion is affected by the density of AuNPs on the shell - the higher the density of AuNPs the shorter the fusion time. All these findings confirm that laser-induced microcapsule fusion is a new type of membrane fusion. This effect helps to study the interior exchange reactions of functional microcapsules, micro-reactors and drug transport across multilayers. PMID:25521939

  2. Modulating Drug Release from Gastric-Floating Microcapsules through Spray-Coating Layers

    PubMed Central

    Tan, Chaoyang Nicholas; Loo, Say Chye Joachim

    2014-01-01

    Floating dosage forms with prolonged gastric residence time have garnered much interest in the field of oral delivery. However, studies had shown that slow and incomplete release of hydrophobic drugs during gastric residence period would reduce drug absorption and cause drug wastage. Herein, a spray-coated floating microcapsule system was developed to encapsulate fenofibrate and piroxicam, as model hydrophobic drugs, into the coating layers with the aim of enhancing and tuning drug release rates. Incorporating fenofibrate into rubbery poly(caprolactone) (PCL) coating layer resulted in a complete and sustained release for up to 8 h, with outermost non-drug-holding PCL coating layer serving as a rate-controlling membrane. To realize a multidrug-loaded system, both hydrophilic metformin HCl and hydrophobic fenofibrate were simultaneously incorporated into these spray-coated microcapsules, with metformin HCl and fenofibrate localized within the hollow cavity of the capsule and coating layer, respectively. Both drugs were observed to be completely released from these coated microcapsules in a sustained manner. Through specific tailoring of coating polymers and their configurations, piroxicam loaded in both the outer polyethylene glycol and inner PCL coating layers was released in a double-profile manner (i.e. an immediate burst release as the loading dose, followed by a sustained release as the maintenance dose). The fabricated microcapsules exhibited excellent buoyancy in simulated gastric fluid, and provided controlled and sustained release, thus revealing its potential as a rate-controlled oral drug delivery system. PMID:25470374

  3. Synthesis of polymeric microcapsule arrays and their use for enzyme immobilization

    NASA Astrophysics Data System (ADS)

    Parthasarathy, Ranjani V.; Martin, Charles R.

    1994-05-01

    CURRENT methods for immobilizing enzymes for use in bioreactors and biosensors1-20 include adsorption on or covalent attachment to a support2-4, micro-encapsulation5,6, and entrapment within a membrane/film7,8,11-20 or gel9. The ideal immobilization method should employ mild chemical conditions, allow for large quantities of enzyme to be immobilized, provide a large surface area for enzyme-substrate contact within a small total volume, minimize barriers to mass transport of substrate and product, and provide a chemically and mechanically robust system. Here we describe a method for enzyme immobilization that satisfies all of these criteria. We have developed a template-based synthetic method that yields hollow polymeric microcapsules of uniform diameter and length. These microcapsules are arranged in a high-density array in which the individual capsules protrude from a surface like the bristles of a brush. We have developed procedures for filling these microcapsules with high concentrations of enzymes. The enzyme-loaded microcapsule arrays function as enzymatic bioreactors in both aqueous solution and organic solvents.

  4. Microfluidic Production of Semipermeable Microcapsules by Polymerization-Induced Phase Separation.

    PubMed

    Kim, Bomi; Jeon, Tae Yoon; Oh, You-Kwan; Kim, Shin-Hyun

    2015-06-01

    Semipermeable microcapsules are appealing for controlled release of drugs, study of cell-to-cell communication, and isolation of enzymes or artificial catalysts. Here, we report a microfluidic strategy for creating monodisperse microcapsules with size-selective permeability using polymerization-induced phase separation. Monodisperse water-in-oil-in-water (W/O/W) double-emulsion drops, whose ultrathin middle layer is composed of photocurable resin and inert oil, are generated in a capillary microfluidic device, and irradiated by UV light. Upon UV illumination, the monomers are photopolymerized, which leads to phase separation between the polymerized resin and the oil within the ultrathin shell. Subsequent dissolution of the oil leaves behind regular pores in the polymerized membrane that interconnect the interior and exterior of the microcapsules, thereby providing size-selective permeability. The degree of phase separation can be further tuned by adjusting the fraction of oil in the shell or the affinity of the oil to the monomers, thereby enabling the control of the cutoff value of permeation. High mechanical stability and chemical resistance of the microcapsules, as well as controllable permeability and high encapsulation efficiency, will provide new opportunity in a wide range of applications. PMID:26020458

  5. Effects of process parameters on the properties of biocompatible ibuprofen-loaded microcapsules.

    PubMed

    Valot, P; Baba, M; Nedelec, J-M; Sintes-Zydowicz, N

    2009-03-18

    The objective of this study was to obtain an optimum formulation for microencapsulating Ibuprofen. This was achieved by investigating various factors which influenced the microcapsule size. Considering Ibuprofen as a lipophilic model drug, biocompatible Ibuprofen-loaded microcapsules in the size range of 20-60microm were prepared by the water in oil emulsion-solvent evaporation method. An aqueous surfactant phase was used as the continuous external phase (W), a biocompatible organic solvent dissolving Ibuprofen was used as oil phase (O), in addition with a low boiling solvent. The biocompatible polymeric microcapsule membrane was composed of Eudragit RSPO or Ethylcellulose. The influence of various process parameters, such as the volatile organic solvent, the oily core, the stirring rate, on the characteristics of microcapsules was investigated. The encapsulation yield of Ibuprofen close to 100%, whatever the polymer type, was determined by UV-vis experiments, in accordance with the results obtained by (13)C NMR spectroscopy. An innovative technique, DSC-based thermoporosimetry, was used for the estimation of the loading rate of Ibuprofen. The results indicated that this developed analytical method had to be improved since DSC-transitions accounted to free and enclosed Ibuprofen were observed and altered the accuracy of the results. PMID:19084583

  6. In vitro release properties of encapsulated blueberry (Vaccinium ashei) extracts.

    PubMed

    Flores, Floirendo P; Singh, Rakesh K; Kerr, William L; Phillips, Dennis R; Kong, Fanbin

    2015-02-01

    We aimed to determine the effect of encapsulation on the release properties of blueberry extracts during simulated gastrointestinal digestion. An ethanolic pomace extract was microencapsulated with whey protein isolate via spray drying. The in vitro release of monomeric anthocyanins, phenolics and ferric reducing antioxidant activity of the microcapsules (W) were evaluated for the microcapsules and two non-encapsulated systems: ethanolic pomace extract (P) and freeze-dried juice (F). Concentrations of anthocyanin and phenolics were normalised prior to digestion. Results showed that antioxidant activity was in the order of: F>W>P. Regardless of encapsulation, more phenolics were released from W and P than F. Anthocyanin concentration decreased after intestinal digestion for W, but remained constant for P and F. MALDI-MS showed similar spectra for P and F but not for W. The spray-dried product has comparable release characteristics to freeze-dried juice, and may be investigated for food applications. PMID:25172704

  7. Photonic monitoring of chitosan nanostructured alginate microcapsules for drug release

    NASA Astrophysics Data System (ADS)

    Khajuria, Deepak Kumar; Konnur, Manish C.; Vasireddi, Ramakrishna; Roy Mahapatra, D.

    2015-02-01

    By using a novel microfluidic set-up for drug screening applications, this study examines delivery of a novel risedronate based drug formulation for treatment of osteoporosis that was developed to overcome the usual shortcomings of risedronate, such as its low bioavailability and adverse gastric effects. Risedronate nanoparticles were prepared using muco-adhesive polymers such as chitosan as matrix for improving the intestinal cellular absorption of risedronate and also using a gastric-resistant polymer such as sodium alginate for reducing the gastric inflammation of risedronate. The in-vitro characteristics of the alginate encapsulated chitosan nanoparticles are investigated, including their stability, muco-adhesiveness, and Caco-2 cell permeability. Fluorescent markers are tagged with the polymers and their morphology within the microcapsules is imaged at various stages of drug release.

  8. Bubble-cell interactions with laser-activated polymeric microcapsules

    NASA Astrophysics Data System (ADS)

    Versluis, Michel; Lajoinie, Guillaume; van Rooij, Tom; Skachkov, Ilya; Kooiman, Klazina; de Jong, Nico; Physics of Fluids Group, University of Twente Team; Biomedical Engineering, Erasmus MC Team

    2015-11-01

    Polymeric microcapsules that are made light-absorbing by the addition of a dye in their shell can generate cavitation microbubbles with spatiotemporal control when irradiated by a pulsed laser. These particles less than 3 μm in size can circulate through the body, bind to tissues and are expected to be readily detected, even if a single cavitation bubble is produced. In this paper, we study the impact of such cavitation bubbles on a cell monolayer and quantify it in terms of cell poration and cell viability. Two capsules formulations were used; the first one encapsulates a low boiling point oil and induced less cell damage than the second that was loaded with a high boiling point oil. We also report the generation of stable bubbles by the first capsule formulation that completely absorb the cells in their close vicinity. Physics of Fluid group MIRA Institute for Biomedical Technology and Technical Medicine MESA+ Institute for Nanotechnology.

  9. Fabrication of redox-responsive magnetic protein microcapsules from hen egg white by the sonochemical method.

    PubMed

    Zhong, Shuangling; Cui, Xuejun; Tian, Fangyuan

    2015-01-01

    Redox-responsive magnetic protein microcapsules with Fe3O4 magnetic nanoparticles (MNPs) encapsulated inside have been obtained using a facile, cost-effective and fast sonochemical method from hen egg white proteins. Such prepared redox-responsive magnetic hen egg white protein microcapsules (MHEWPMCs) could be easily manipulated to do magnetic-guided targeting delivery. The synchronous loading of the hydrophobic dye Coumarin 6 as a model of drug into MHEWPMCs was readily achieved during the fabrication of MHEWPMCs by dissolving them into the oil phase before ultrasonication. TEM images indicated that Fe3O4 MNPs were encapsulated in MHEWPMCs. Confocal laser scanning microscopic images indicated that the dye was distributed evenly in the MHEWPMCs and no leakage of dye from the MHEWPMCs was observed due to the protection of protein shells. The MHEWPMCs are potential candidates as attractive carriers for drug targeting delivery and stimuli-responsive release due to their magnetic and redox responsiveness of the disulfide in the microcapsule shells. PMID:26300460

  10. Characterization of Encapsulated Berberine in Yeast Cells of Saccharomyces cerevisiae

    PubMed Central

    Salari, Roshanak; Rajabi, Omid; Khashyarmanesh, Zahra; Fathi Najafi, Mohsen; Fazly Bazzaz, BiBi Sedigheh

    2015-01-01

    Berberine was loaded in yeast cells of Saccharomyces cerevisiaeas a novel pharmaceutical carrier to improve the treatment ofmany diseases. The yeast-encapsulated active materialsshowedhigh stability and bioavailability due to the enhanced solubility and sustained releasing. In this study, different characteristics of prepared berberine loaded yeast cells (loading capacity, release kinetic order, MIC and stability) were evaluatedby different analytical methods (fluorescence spectroscopy, HPLC and SEM).The loading capacity was about 78% ± 0.6%.Berberine release patterns of microcapsules happened in two different stages and followed by zero and first-order kinetic,respectively. About 99% of all active material released during 34 h. MIC was improved by berberine loaded microcapsules in comparison withberberine powder. The microcapsules were completely stable. Berberine loaded Sac. Cerevisiae could be considered as a favorite sustained release drug delivery system. The yeast would be applied as an efficient carrier to improve various properties of different active materials. PMID:26664393

  11. Magnetically triggered release of molecular cargo from iron oxide nanoparticle loaded microcapsules

    NASA Astrophysics Data System (ADS)

    Carregal-Romero, Susana; Guardia, Pablo; Yu, Xiang; Hartmann, Raimo; Pellegrino, Teresa; Parak, Wolfgang J.

    2014-12-01

    Photothermal release of cargo molecules has been extensively studied for bioapplications. For instance, microcapsules decorated with plasmonic nanoparticles have been widely used in in vitro assays. However, some concerns about their suitability for some in vivo applications cannot be easily overcome, in particular the limited penetration depth of light (even infrared). Magnetic nanoparticles are alternative heat-mediators for local heating, which can be triggered by applying an alternating magnetic field (AMF). AMFs are much less absorbed by tissue than light and thus can penetrate deeper overcoming the above mentioned limitations. Here we present iron oxide nanocube-modified microcapsules as a platform for magnetically triggered molecular release. Layer-by-layer assembled polyelectrolyte microcapsules with 4.6 μm diameter, which had 18 nm diameter iron oxide nanocubes integrated in their walls, were synthesized. The microcapsules were further loaded with an organic fluorescent polymer (Cascade Blue-labelled dextran), which was used as a model of molecular cargo. Through an AMF the magnetic nanoparticles were able to heat their surroundings and destroy the microcapsule walls, leading to a final release of the embedded cargo to the surrounding solution. The cargo release was monitored in solution by measuring the increase in both absorbance and fluorescence signal after the exposure to an AMF. Our results demonstrate that magnetothermal release of the encapsulated material is possible using magnetic nanoparticles with a high heating performance.Photothermal release of cargo molecules has been extensively studied for bioapplications. For instance, microcapsules decorated with plasmonic nanoparticles have been widely used in in vitro assays. However, some concerns about their suitability for some in vivo applications cannot be easily overcome, in particular the limited penetration depth of light (even infrared). Magnetic nanoparticles are alternative heat

  12. Encapsulated liquid sorbents for carbon dioxide capture.

    PubMed

    Vericella, John J; Baker, Sarah E; Stolaroff, Joshuah K; Duoss, Eric B; Hardin, James O; Lewicki, James; Glogowski, Elizabeth; Floyd, William C; Valdez, Carlos A; Smith, William L; Satcher, Joe H; Bourcier, William L; Spadaccini, Christopher M; Lewis, Jennifer A; Aines, Roger D

    2015-01-01

    Drawbacks of current carbon dioxide capture methods include corrosivity, evaporative losses and fouling. Separating the capture solvent from infrastructure and effluent gases via microencapsulation provides possible solutions to these issues. Here we report carbon capture materials that may enable low-cost and energy-efficient capture of carbon dioxide from flue gas. Polymer microcapsules composed of liquid carbonate cores and highly permeable silicone shells are produced by microfluidic assembly. This motif couples the capacity and selectivity of liquid sorbents with high surface area to facilitate rapid and controlled carbon dioxide uptake and release over repeated cycles. While mass transport across the capsule shell is slightly lower relative to neat liquid sorbents, the surface area enhancement gained via encapsulation provides an order-of-magnitude increase in carbon dioxide absorption rates for a given sorbent mass. The microcapsules are stable under typical industrial operating conditions and may be used in supported packing and fluidized beds for large-scale carbon capture. PMID:25652243

  13. Encapsulated liquid sorbents for carbon dioxide capture

    NASA Astrophysics Data System (ADS)

    Vericella, John J.; Baker, Sarah E.; Stolaroff, Joshuah K.; Duoss, Eric B.; Hardin, James O.; Lewicki, James; Glogowski, Elizabeth; Floyd, William C.; Valdez, Carlos A.; Smith, William L.; Satcher, Joe H.; Bourcier, William L.; Spadaccini, Christopher M.; Lewis, Jennifer A.; Aines, Roger D.

    2015-02-01

    Drawbacks of current carbon dioxide capture methods include corrosivity, evaporative losses and fouling. Separating the capture solvent from infrastructure and effluent gases via microencapsulation provides possible solutions to these issues. Here we report carbon capture materials that may enable low-cost and energy-efficient capture of carbon dioxide from flue gas. Polymer microcapsules composed of liquid carbonate cores and highly permeable silicone shells are produced by microfluidic assembly. This motif couples the capacity and selectivity of liquid sorbents with high surface area to facilitate rapid and controlled carbon dioxide uptake and release over repeated cycles. While mass transport across the capsule shell is slightly lower relative to neat liquid sorbents, the surface area enhancement gained via encapsulation provides an order-of-magnitude increase in carbon dioxide absorption rates for a given sorbent mass. The microcapsules are stable under typical industrial operating conditions and may be used in supported packing and fluidized beds for large-scale carbon capture.

  14. Towards Theranostic Multicompartment Microcapsules: in-situ Diagnostics and Laser-induced Treatment

    PubMed Central

    Xiong, Ranhua; Soenen, Stefaan J.; Braeckmans, Kevin; Skirtach, Andre G.

    2013-01-01

    Paving the way towards the application of polyelectrolyte multilayer capsules in theranostics, we describe diagnostic multi-functionality and drug delivery using multicompartment polymeric capsules which represent the next generation of drug delivery carriers. Their versatility is particularly important for potential applications in the area of theranostics wherein the carriers are endowed with the functionality for both diagnostics and therapy. Responsiveness towards external stimuli is attractive for providing controlled and on-demand release of encapsulated materials. An overview of external stimuli is presented with an emphasis on light as a physical stimulus which has been widely used for activation of microcapsules and release of their contents. In this article we also describe existing and new approaches to build multicompartment microcapsules as well as means available to achieve controlled and triggered release from their subcompartments, with a focus on applications in theranostics. Outlook for future directions in the area are highlighted. PMID:23471141

  15. Effect of interfacial free energy on the formation of polymer microcapsules by emulsification/freeze-drying.

    PubMed

    Yin, Weisi; Yates, M Z

    2008-02-01

    Hollow polymer microparticles with a single opening on the surface were formed by freeze-drying aqueous polymer colloids swollen with solvent. The results show that the particle morphology is due to phase separation in the polymer emulsion droplets upon freezing in liquid nitrogen, and that morphological changes are driven largely by lowering interfacial free energy. The effects of added surfactant, volume fraction of solvent, type of solvent, and processing conditions on the particle morphology were examined and compared to theoretical predictions. The dried hollow particles were resuspended in a dispersing media and exposed to a second swelling solvent to close the surface opening and form microcapsules. The interfacial free energy difference between the inside and outside surfaces is the driving force for closing the hole on the surface. The emulsification/freeze-drying technique can be used to encapsulate hydrophilic additives in the core of the microcapsules, demonstrating the potential of the technique in controlled-release applications. PMID:18173290

  16. Alginate polylysine microcapsules as immune barrier: permeability of cytokines and immunoglobulins over the capsule membrane.

    PubMed

    Kulseng, B; Thu, B; Espevik, T; Skjåk-Braek, G

    1997-01-01

    Transplantation of pancreatic islets in alginate polylysine microcapsules is a potential useful method for treating type I diabetes. In this study, the permeability for alginate-polylysine microcapsules to cytokines an immunoglobulines has been investigated by a newly developed method. Magnetic monodisperse polymer particles (Dynabeads) coated with antibodies against selected proteins were encapsulated in 0.7 mm alginate polylysine microcapsules. The capsule membrane permeability to IgG (150 kDa), Transferrin (81 kDa), Tumor necrosis factor (TNF, 51 kDa), Interleukin-1 beta (IL-1 beta, 17.5 kDa), and insulin (5.8 kDa) was estimated by measuring the binding of 125I-labeled proteins to the encapsulated antibody coated Dynabeads. Capsules with an inhomogeneous solid gel core were made of alginates with high guluronic or high mannuronic acid content and poly-L (PLL)- or poly-D-lysine (PDL) of concentrations varied from 0.05-0.2%. The various capsules examined were all impermeable to IgG. The capsules made with a PLL-, but not PDL-membranes were permeable for transferrin. IL-1 beta was found to penetrate all of the different capsule types. The high-G capsules, however, could be made impermeable to TNF and still allowed transferrin to pass. The permeability of these capsules to IL-1 beta, but not to TNF was confirmed in an assay where mouse islets of Langerhans were incubated with TNF and IL-1 beta, and comparing the IL-6 for encapsulated and non-encapsulated islets. PMID:9258512

  17. The kinetics of the swelling process and the release mechanisms of Coriandrum sativum L. essential oil from chitosan/alginate/inulin microcapsules.

    PubMed

    Dima, Cristian; Pătraşcu, Livia; Cantaragiu, Alina; Alexe, Petru; Dima, Ştefan

    2016-03-15

    The encapsulation by spray drying method of coriander essential oil (CEO) in various materials (chitosan, alginate, chitosan/alginate, chitosan/inulin) was studied. The viscoelastic properties of the oil-in-water (O/W) emulsions and the characteristics of CEO-loaded microcapsules like morphology, moisture, wettability, solubility, flowability properties, swelling and release mechanisms were investigated. The chitosan microcapsules had a brain-like structure while the alginate and chitosan/alginate microcapsules are spherical with a smooth surface. The Compressibility Index (CI=29.09-32.25%) and Hausner Ratio (HR=1.38-1.44) values showed that all the microcapsules prepared correspond to the "poor" flowability powders group. The chitosan microcapsules exhibited the maximum release rate at pH 2.5 while the alginate microcapsules exhibited the maximum release rate at pH 6.5. Kinetics and mechanism of CEO release were studied using various mathematical models such as, zero order, first order, Higuchi model and Peppas model. The diffusional exponent (n) values of Peppas equation explains a non Fickian transport mechanism and diffusion or diffusion-swelling controlled process. PMID:26575710

  18. Reconfigurable environmentally adaptive computing

    NASA Technical Reports Server (NTRS)

    Coxe, Robin L. (Inventor); Galica, Gary E. (Inventor)

    2008-01-01

    Described are methods and apparatus, including computer program products, for reconfigurable environmentally adaptive computing technology. An environmental signal representative of an external environmental condition is received. A processing configuration is automatically selected, based on the environmental signal, from a plurality of processing configurations. A reconfigurable processing element is reconfigured to operate according to the selected processing configuration. In some examples, the environmental condition is detected and the environmental signal is generated based on the detected condition.

  19. Self-healing coatings containing microcapsule

    NASA Astrophysics Data System (ADS)

    Zhao, Yang; Zhang, Wei; Liao, Le-ping; Wang, Si-jie; Li, Wu-jun

    2012-01-01

    Effectiveness of epoxy resin filled microcapsules was investigated for healing of cracks generated in coatings. Microcapsules were prepared by in situ polymerization of urea-formaldehyde resin to form shell over epoxy resin droplets. Characteristics of these capsules were studied by 3D measuring laser microscope, particle size analyzer, Fourier-transform infrared spectroscopy (FTIR) and differential scanning calorimeter (DSC) to investigate their surface morphology, size distribution, chemical structure and thermal stability, respectively. The results indicate that microcapsules containing epoxy resins can be synthesized successfully. The size is around 100 μm. The rough outer surface of microcapsule is composed of agglomerated urea-formaldehyde nanoparticles. The size and surface morphology of microcapsule can be controlled by selecting different processing parameters. The microcapsules basically exhibit good storage stability at room temperature, and they are chemically stable before the heating temperature is up to approximately 200 °C. The model system of self-healing coating consists of epoxy resin matrix, 10 wt% microencapsulated healing agent, 2 wt% catalyst solution. The self-healing function of this coating system is evaluated through self-healing testing of damaged and healed coated steel samples.

  20. Fabrication of carbon microcapsules containing silicon nanoparticles-carbon nanotubes nanocomposite by sol-gel method for anode in lithium ion battery

    SciTech Connect

    Bae, Joonwon

    2011-07-15

    Carbon microcapsules containing silicon nanoparticles (Si NPs)-carbon nanotubes (CNTs) nanocomposite (Si-CNT-C) have been fabricated by a surfactant mediated sol-gel method followed by a carbonization process. Silicon nanoparticles-carbon nanotubes (Si-CNT) nanohybrids were produced by a wet-type beadsmill method. To obtain Si-CNT nanocomposites with spherical morphologies, a silica precursor (tetraethylorthosilicate, TEOS) and polymer (PMMA) mixture was employed as a structure-directing medium. Thus the Si-CNT/Silica-Polymer microspheres were prepared by an acid catalyzed sol-gel method. Then a carbon precursor such as polypyrrole (PPy) was incorporated onto the surfaces of pre-existing Si-CNT/silica-polymer to generate Si-CNT/Silica-Polymer-PPy microspheres. Subsequent thermal treatment of the precursor followed by wet etching of silica produced Si-CNT-C microcapsules. The intermediate silica/polymer must disappear during the carbonization and etching process resulting in the formation of an internal free space. The carbon precursor polymer should transform to carbon shell to encapsulate remaining Si-CNT nanocomposites. Therefore, hollow carbon microcapsules containing Si-CNT nanocomposites could be obtained (Si-CNT-C). The successful fabrication was confirmed by scanning electron microscopy (SEM) and X-ray diffraction (XRD). These final materials were employed for anode performance improvement in lithium ion battery. The cyclic performances of these Si-CNT-C microcapsules were measured with a lithium battery half cell tests. - Graphical Abstract: Carbon microcapsules containing silicon nanoparticles (Si NPs)-carbon nanotubes (CNTs) nanocomposite (Si-CNT-C) have been fabricated by a surfactant mediated sol-gel method. Highlights: > Polymeric microcapsules containing Si-CNT transformed to carbon microcapsules. > Accommodate volume changes of Si NPs during Li ion charge/discharge. > Sizes of microcapsules were controlled by experimental parameters. > Lithium

  1. UV-Triggered Self-Healing of a Single Robust SiO2 Microcapsule Based on Cationic Polymerization for Potential Application in Aerospace Coatings.

    PubMed

    Guo, Wanchun; Jia, Yin; Tian, Kesong; Xu, Zhaopeng; Jiao, Jiao; Li, Ruifei; Wu, Yuehao; Cao, Ling; Wang, Haiyan

    2016-08-17

    UV-triggered self-healing of single microcapsules has been a good candidate to enhance the life of polymer-based aerospace coatings because of its rapid healing process and healing chemistry based on an accurate stoichiometric ratio. However, free radical photoinitiators used in single microcapsules commonly suffer from possible deactivation due to the presence of oxygen in the space environment. Moreover, entrapment of polymeric microcapsules into coatings often involves elevated temperature or a strong solvent, probably leading to swelling or degradation of polymer shell, and ultimately the loss of active healing species into the host matrix. We herein describe the first single robust SiO2 microcapsule self-healing system based on UV-triggered cationic polymerization for potential application in aerospace coatings. On the basis of the similarity of solubility parameters of the active healing species and the SiO2 precursor, the epoxy resin and cationic photoinitiator are successfully encapsulated into a single SiO2 microcapsule via a combined interfacial/in situ polymerization. The single SiO2 microcapsule shows solvent resistance and thermal stability, especially a strong resistance for thermal cycling in a simulated space environment. In addition, the up to 89% curing efficiency of the epoxy resin in 30 min, and the obvious filling of scratches in the epoxy matrix demonstrate the excellent UV-induced healing performance of SiO2 microcapsules, attributed to a high load of healing species within the capsule (up to 87 wt %) and healing chemistry based on an accurate stoichiometric ratio of the photoinitiator and epoxy resin at 9/100. More importantly, healing chemistry based on a UV-triggered cationic polymerization mechanism is not sensitive to oxygen, extremely facilitating future embedment of this single SiO2 microcapsule in spacecraft coatings to achieve self-healing in a space environment with abundant UV radiation and oxygen. PMID:27463101

  2. Novel B melatonin-loaded chitosan microcapsules: in vitro characterization and antiapoptosis efficacy for aflatoxin B1-induced apoptosis in rat liver.

    PubMed

    El-Gibaly, I; Meki, A M A; Abdel-Ghaffar, S K

    2003-07-01

    The aim of this study was to prepare buoyant (B) melatonin (MT)-loaded chitosan microcapsules having favourable sustained release characteristics (in simulated gastric fluid (SGF), pH 1.2) in comparison with non-buoyant (NB) chitosan particles. The new buoyant microcapsules were prepared by the ionotropic gelation method using sodium lauryl sulfate (NaLS) for coagulation. The microcapsule characteristics were affected by the initial drug and NaLS concentrations, as well as the presence of sodium dioctyl sulfosuccinate (DOS) or pectin with NaLS in the external phase. In general, spherical microcapsules with 36.90-56.23% encapsulation efficiencies, hollow core and satisfactory release properties were produced. The best sustained release profiles (t(50%): 5h) with near zero-order kinetics were observed with the higher theoretical payload microcapsules prepared with both NaLS and DOS in a 1:2 ratio. In vivo studies were also carried out to exploit the protective effect of the MT-loaded NaLS-DOS microcapsules against aflatoxin B1 (AFB1)-induced toxicity (liver apoptosis) in male rats. The results implied that apoptotic rate was significantly reduced when MT or its microcapsules formulation was co-administered with AFB1. The levels of the oxidative stress indices (malondialdehyde (MDA), a lipid peroxidation product and nitric oxide (NO)) in liver tissues were significantly reduced, while the levels of the hepatic antioxidants (glutathione (GSH) and zinc (Zn), as well as the enzyme activities of glutathione reductase (GR), glutathione peroxidase (GSPx) and glutathione-S-transferase (GST)) which act as antiapoptosis were significantly increased as compared to AFB1 group (without MT). MT microcapsules appeared more effective in reduction of apoptotic rate than free MT as indicated by the decline of caspase-3 activities (an apoptotic marker) and confirmed by histopathology. PMID:12818806

  3. Fabrication of Microcapsules for Dye-Doped Polymer-Dispersed Liquid Crystal-Based Smart Windows.

    PubMed

    Kim, Mingyun; Park, Kyun Joo; Seok, Seunghwan; Ok, Jong Min; Jung, Hee-Tae; Choe, Jaehoon; Kim, Do Hyun

    2015-08-19

    A dye-doped polymer-dispersed liquid crystal (PDLC) is an attractive material for application in smart windows. Smart windows using a PDLC can be operated simply and have a high contrast ratio compared to those of other devices that employed photochromic or thermochromic material. However, in conventional dye-doped PDLC methods, dye contamination can cause problems and has a limited degree of commercialization of electric smart windows. Here, we report on an approach to resolve dye-related problems by encapsulating the dye in monodispersed capsules. By encapsulation, a fabricated dye-doped PDLC had a contrast ratio of >120 at 600 nm. This fabrication method of encapsulating the dye in a core-shell structured microcapsule in a dye-doped PDLC device provides a practical platform for dye-doped PDLC-based smart windows. PMID:26192469

  4. Radiopaque alginate microcapsules for X-ray visualization and immunoprotection of cellular therapeutics.

    PubMed

    Barnett, B P; Kraitchman, D L; Lauzon, C; Magee, C A; Walczak, P; Gilson, W D; Arepally, A; Bulte, J W M

    2006-01-01

    Alginate-poly-L-lysine-alginate (APA) microcapsules have been explored as vehicles for therapeutic drug and cell delivery. The permselectivity of these capsules provides a unique means of controlled drug release and immunoisolation of encapsulated cells. Immunoisolation is especially attractive as it abrogates the need for chronic immunosuppressive therapy and opens up the possibility for the delivery of numerous cell sources including xenogeneic grafts. APA microcapsules containing cellular therapeutics have proven effective in the short-term treatment of a wide range of diseases requiring enzyme or endocrine replacement therapy, including type I diabetes. If these microcapsules could be noninvasively monitored with X-ray imaging modalities (i.e., fluoroscopy, CT, and digital subtraction angiography), questions such as the ideal transplantation site, the best means of delivery, and the long-term survival of grafts could be better addressed. We have developed two novel alginate-based radiopaque microcapsule formulations containing either barium sulfate (Ba X-Caps) or bismuth sulfate (Bi X-Caps). As compared to conventional, nonradiopaque APA capsules, Ba X-Caps and Bi X-Caps containing human cadaveric islets resulted in a decrease in cellular viability of less than 5% up to 14 days after encapsulation. Both radiopaque capsules were found to be permeable to lectins < or =75 kDa, but were impermeable to lectins > or =120 kDa, thus ensuring the blockage of the penetration of antibodies while allowing free diffusion of insulin and nutrients. The glucose-responsive insulin secretion of the radiopaque encapsulated human islets was found to be unaltered compared to that of unlabeled controls, with human C-peptide levels ranging from 3.21 to 2.87 (Ba X-Caps) and 3.23 to 2.87 (Bi X-Caps) ng/islet at 7 and 14 days postencapsulation, respectively. Using fluoroscopy, both Ba X-Caps and Bi X-Caps could be readily visualized as single radiopaque entities in vitro. Furthermore

  5. Fabrication of homogeneously cross-linked, functional alginate microcapsules validated by NMR-, CLSM- and AFM-imaging.

    PubMed

    Zimmermann, H; Hillgärtner, M; Manz, B; Feilen, P; Brunnenmeier, F; Leinfelder, U; Weber, M; Cramer, H; Schneider, S; Hendrich, C; Volke, F; Zimmermann, U

    2003-05-01

    Cross-linked alginate microcapsules of sufficient mechanical strength can immunoisolate cells for the long-term treatment of hormone and other deficiency diseases in human beings. However, gelation of alginate by external Ba(2+) (or other divalent cations) produces non-homogeneous cross-linking of the polymeric mannuronic (M) and guluronic (G) acid chains. The stability of such microcapsules is rather limited. Here, we show that homogeneous cross-linking can be achieved by injecting BaCl(2) crystals into alginate droplets before they come into contact with external BaCl(2). The high effectiveness of this crystal gun method is demonstrated by confocal laser scanning microscopy and by advanced nuclear magnetic resonance imaging. Both techniques gave clear-cut evidence that homogeneous cross-linkage throughout the microcapsule is only obtained with simultaneous internal and external gelation. Atomic force microscopy showed a very smooth surface topography for microcapsules made by the crystal gun method, provided that excess Ba(2+) ions were removed immediately after gelation. In vitro experiments showed greatly suppressed swelling for crystal gun microcapsules. Even alginate extracted from Lessonia nigrescens (highly biocompatible) yielded microcapsules with long-term mechanical stability not hitherto possible. Encapsulation of rat islets, human monoclonal antibodies secreting hybridoma cells and murine mesenchymal stem cells transfected with cDNA encoding for bone morphogenetic protein (BMP-4) revealed that injection of BaCl(2) crystals has no adverse side effects on cell viability and function. However, the release of low-molecular weight factors (such as insulin) may be delayed when using alginate concentrations in the usual range. PMID:12628829

  6. Alginate microcapsule for propagation and directed differentiation of hESCs to definitive endoderm.

    PubMed

    Chayosumrit, Methichit; Tuch, Bernard; Sidhu, Kuldip

    2010-01-01

    Human embryonic stem cells (hESCs) are potential renewable sources of cells in replacement therapies for many diseases including type 1 diabetes. We have established a three dimensional (3D) model to culture and differentiate hESCs that are encapsulated in calcium alginate microcapsules. This system promotes cellular interactions that are essential for both maintaining pluripotency and differentiation. This 3D model also provides opportunity to separate out hESCs from fibroblasts used as feeder layer during culture. In this study, we compared the viability and proliferation of the encapsulated hESCs cultured in serum replacement (SR) medium, human fetal fibroblast-conditioned medium (hFF-CM), in the presence and absence of Y-27632, a ROCK inhibitor. Treatment of hESCs with Y-27632 promoted cell survival, cell cluster formation and proliferation rate in both SR medium and hFF-CM. These encapsulated hESC clusters were then directly differentiated to definitive endoderm cells that expressed mesendoderm (Brachyury 70-fold), definitive endoderm (SOX17>300-fold, FOXA2>800-fold, and CXCR4>100-fold) and primitive gut tube (HNF1beta>120-fold) as compared to the undifferentiated hESCs. These data show that microcapsules can be used for differentiation of hESCs into definitive endoderm in 3D and could have potential application for immune-isolation and prevention of teratomas formation of hESCs during transplantation. PMID:19833385

  7. All-Aqueous Electrosprayed Emulsion for Templated Fabrication of Cytocompatible Microcapsules.

    PubMed

    Song, Yang; Chan, Yau Kei; Ma, Qingming; Liu, Zhou; Shum, Ho Cheung

    2015-07-01

    Encapsulation of biomolecules and cells in hydrogel capsules via emulsion templating frequently induces an irreversible loss of bioactivity, because of the use of nonaqueous solvents. Here, we introduce an all-aqueous electrospray (AAE) approach to generate aqueous two-phase emulsion droplets, and we use them as templates to fabricate microcapsules with preserved cell viability. The approach allows formation of monodisperse microparticles with tunable sizes, variable compositions, and interior architectures in a mild gelation process. This technique potentially benefits a variety of new biomedical applications, such as delivery of bioactive proteins, transplantation of living cells, and assembly of cell-mimicking structures. PMID:26053733

  8. Reconfigurable video tracker

    NASA Astrophysics Data System (ADS)

    Groves, Gillian K.; White, Spencer W.; Vahey, Michael D.; Harding, John A.

    1999-07-01

    Reconfigurable computing using SRAM-based field programmable gate arrays (FPGAs) can achieve significant computational performance advantage over conventional programmable processors. Since FPGAs can be customized, reconfigurable computers can provide optimal logic-circuitry for distinct phases of an application resulting in superior performance compared to generic multi-purpose hardware implementations. This performance improvement can be accomplished by reallocating logic resources to address the critical task at-hand. Consequently, not only can reconfigurable processors provide higher performance than programmable processors; they also enable common module architectures useful for multiple application or programs. In this paper, we will describe a fielded, ruggedized, fully programmable, single card, image-based tracking system using a reconfigurable computing module. The reconfigurable computing board contains multiple FPGAs, which can be customized at-request by loading configuration data from the host processor to the module over the Peripheral Component Interface (PCI) bus. Configurations can be selectively loaded to a specific FPGA or multiple configurations can be loaded simultaneously to different devices. This system provides multiple video tracking algorithms, automatic and manual target acquisition, RS-170 video input/output, and command/data I/O on a single 6U VME format card. While the initial application for this reconfigurable system was image-based target tracking, its hardware reconfigurability allows it to be applied to a wide variety of image and signal processing applications, such as automatic target recognition, IR search and track, and image enhancement.

  9. Enzymatic hydrolysis of organic-core microcapsules to produce aqueous-core microcapsules.

    PubMed

    Breguet, Veronique; Vojinovic, Vojislav; Von Stockar, Urs; Marison, Ian W

    2008-05-01

    This paper describes the development of a new method to obtain aqueous-core microcapsules from organic-core capsules. The direct production of microcapsules, using tripropionin as organic material, followed by the hydrolysis of the core by a lipase was investigated. The enzymatic study showed that the enzyme obeyed a Michaelis-Menten mechanism and conditions for optimal activity were pH 7.5, 25-37 degrees C and 0% NaCl. Under these conditions, incubation of tripropionin-alginate microcapsules in a buffer containing the enzyme successfully produced aqueous-core capsules with reduced accumulation of alginate in the core in approximately 3 h. PMID:18382924

  10. Considerations for successful transplantation of encapsulated pancreatic islets.

    PubMed

    de Vos, P; Hamel, A F; Tatarkiewicz, K

    2002-02-01

    Encapsulation of pancreatic islets allows for transplantion in the absence of immunosuppression. The technology is based on the principle that transplanted tissue is protected for the host immune system by an artificial membrane. Encapsulation offers a solution to the shortage of donors in clinical islet transplantation because it allows animal islets or insulin-producing cells engineered from stem cells to be used. During the past two decades three major approaches to encapsulation have been studied. These include intravascular macrocapsules, which are anastomosed to the vascular system as AV shunt; extravascular macrocapsules, which are mostly diffusion chambers transplanted at different sites; and extravascular microcapsules transplanted in the peritoneal cavity. The advantages and pitfalls of these three approaches are discussed and compared in the light of their applicability to clinical islet transplantation. All systems have been shown to be successful in preclinical studies but not all approaches meet the technical or physiological requirements for application in human beings. The extravascular approach has advantages over the intravascular because since it is associated with less complications such as thrombosis and infection. Microcapsules, due to their spatial characteristics, have a better diffusion capacity than macrocapsules. Recent progress in biocompatibility of microcapsules has brought this technology close to clinical application. Critical issues such as limitations in the functional performance and survival are being discussed. The latest results show that both issues can be solved by the transplantation of microencapsulated islets close to blood vessels in prevascularized solid supports. PMID:11935147

  11. Silica Microcapsules for Long-Term, Robust, and Reliable Room Temperature RNA Preservation.

    PubMed

    Puddu, Michela; Stark, Wendelin J; Grass, Robert N

    2015-06-24

    As a consequence of the latest revolutionary discoveries on its functions, RNA is certainly the hottest topic at the moment, being an exceptional tool in biology as well as in medicine. For the various applications, a proper RNA storage is required to prevent the degradation of this extremely unstable molecule. Here a novel freezing-free RNA storage strategy is presented, based on its encapsulation in silica spheres. The silica microcapsules protect the RNA by providing a water-free environment. In this way RNA can be safely stored for prolonged periods of time at ambient and elevated temperatures, maintaining its original integrity, as proved by gel-electrophoresis, capillary electrophoresis, and real-time reverse transcription-polymerase chain reaction (RT-qPCR). The RNA degradation rate at 65 °C in silica microcapsules is approximately ten times smaller in comparison to dry RNA samples or to samples stored in RNAstable matrix, a commercially available product. Moreover, RNA half-life at 65 °C is nearly identical to that of DNA within the silica microcapsules. Samples intended for use in gene expression are compatible with further analysis (RT-qPCR, Sanger sequencing). The novel storage technology permits to safely handle, store, and transport RNA samples, avoiding the expensive shipments and the problems of space presented by freezing-based strategies. PMID:25899883

  12. Microcapsules and 3D customizable shelled microenvironments from laser direct-written microbeads.

    PubMed

    Kingsley, David M; Dias, Andrew D; Corr, David T

    2016-10-01

    Microcapsules are shelled 3D microenvironments, with a liquid core. These core-shelled structures enable cell-cell contact, cellular proliferation and aggregation within the capsule, and can be utilized for controlled release of encapsulated contents. Traditional microcapsule fabrication methods provide limited control of capsule size, and are unable to control capsule placement. To overcome these limitations, we demonstrate size and spatial control of poly-l-lysine and chitosan microcapsules, using laser direct-write (LDW) printing, and subsequent processing, of alginate microbeads. Additionally, microbeads were used as volume pixels (voxels) to form continuous 3D hydrogel structures, which were processed like capsules, to form custom shelled aqueous-core 3D structures of prescribed geometry; such as strands, rings, and bifurcations. Heterogeneous structures were also created with controlled initial locations of different cell types, to demonstrate the ability to prescribe cell signaling (heterotypic and homotypic) in co-culture conditions. Herein, we demonstrate LDW's ability to fabricate intricate 3D structures, essentially with "printed macroporosity," and to precisely control structural composition by bottom-up fabrication in a bead-by-bead manner. The structural and compositional control afforded by this process enables the creation of a wide range of new constructs, with many potential applications in tissue engineering and regenerative medicine. Biotechnol. Bioeng. 2016;113: 2264-2274. © 2016 Wiley Periodicals, Inc. PMID:27070458

  13. Feasibility investigation of self-healing cementitious composite using oil core/silica gel shell passive smart microcapsules

    NASA Astrophysics Data System (ADS)

    Yang, Zhengxian; Hollar, John; He, Xiaodong; Shi, Xianming

    2009-07-01

    This paper presents our work in the concept exploration of a new family of self-healing materials that hold promise for "crack-free" cementitious composites. This innovative system features the design of passive smart microcapsules with oil core and silica gel shell, prepared through an interfacial self-assembly process and sol-gel reaction. Methylmethacrylate monomer and triethylborane were chosen as the healing agent and the catalyst, and were microencapsulated respectively. The microcapsules were dispersed in fresh cement mortar along with carbon microfibers. For the hardened mortar, self-healing can be triggered by crack propagation through the microcapsules, which then releases the healing agent and the catalyst into the microcracks. Polymerization of the healing agent is initiated by contact with the catalyst, bonding the crack faces. Surface analytical tools such as optical microscope and field emission scanning electron microscope were used to examine the localized morphology and encapsulation of the passive smart microcapsules. The self-healing effect was evaluated using gas permeability and electrochemical impedance measurements.

  14. Uniform titanium dioxide (TiO(2)) microcapsules prepared by glass membrane emulsification with subsequent solvent evaporation.

    PubMed

    Supsakulchai, A; Ma, G H; Nagai, M; Omi, S

    2002-01-01

    Anatase-type titanium dioxide (TiO(2)) was encapsulated using an Shirasu porous glass (SPG) membrane emulsification technique and followed by solvent evaporation. The oil phase, consisting of fine#10; powder of anatase TiO(2), Disperbyk-180, the hydrophobic oil phase additive, and polymer wall solution, was pushed through the membrane pores into the aqueous phase of poly(vinyl alcohol) and sodium dodecyl sulfate to form the solid-in-oil-in water, (S/O)/W, emulsion droplets. Three types of styrene-based copolymer poly(styrene-co-acrylic acid) (PS-AA), poly(styrene-co-2-ethyl hexyl acrylate) (PS-2EHA) and poly(styrene-co-dimethyl aminoethylmethacrylate) (PS-DMAEMA) were used as an encapsulating shell. Uniform droplets were successfully obtained by modifying the oil phase using methyl laurate or hexadecanol as the oil phase additive, together with carefully monitoring the emulsification flow rate during the emulsification. The (S/O)/W emulsion was gently stirred in a sealed reactor, and evacuation of solvent started under moderate heating with increasing a vacuum intensity. Those uniform-sized TiO(2) microcapsules revealed fine porous morphologies on their surfaces as a result of a mild phase separation induced from the addition of the oil phase additive. The encapsulation efficiency was influenced by the stability of TiO(2) in the oil phase, the polymer wall employed, and the operational control of the glass membrane emulsification process. The membrane emulsification process could prepare the TiO(2) microcapsules with about approximately 6-8.5 wt% of encapsulation loadings. PS-AA and PS-2EHA copolymers provided better encapsulation efficiency compared to PS-DMAEMA. SPG membranes with 1.42, 2.8, 5.25, 7.0, or 9.5 microm were employed and 2-20 microm microcapsules were subsequently obtained. PMID:12396381

  15. Multicompartmental Microcapsules from Star Copolymer Micelles

    SciTech Connect

    Choi, Ikjun; Malak, Sidney T.; Xu, Weinan; Heller, William T.; Tsitsilianis, Constantinos; Tsukruk, Vladimir V.

    2013-02-26

    We present the layer-by-layer (LbL) assembly of amphiphilic heteroarm pH-sensitive star-shaped polystyrene-poly(2-pyridine) (PSnP2VPn) block copolymers to fabricate porous and multicompartmental microcapsules. Pyridine-containing star molecules forming a hydrophobic core/hydrophilic corona unimolecular micelle in acidic solution (pH 3) were alternately deposited with oppositely charged linear sulfonated polystyrene (PSS), yielding microcapsules with LbL shells containing hydrophobic micelles. The surface morphology and internal nanopore structure of the hollow microcapsules were comparatively investigated for shells formed from star polymers with a different numbers of arms (9 versus 22) and varied shell thickness (5, 8, and 11 bilayers). The successful integration of star unimers into the LbL shells was demonstrated by probing their buildup, surface segregation behavior, and porosity. The larger arm star copolymer (22 arms) with stretched conformation showed a higher increment in shell thickness due to the effective ionic complexation whereas a compact, uniform grainy morphology was observed regardless of the number of deposition cycles and arm numbers. Small-angle neutron scattering (SANS) revealed that microcapsules with hydrophobic domains showed different fractal properties depending upon the number of bilayers with a surface fractal morphology observed for the thinnest shells and a mass fractal morphology for the completed shells formed with the larger number of bilayers. Moreover, SANS provides support for the presence of relatively large pores (about 25 nm across) for the thinnest shells as suggested from permeability experiments. The formation of robust microcapsules with nanoporous shells composed of a hydrophilic polyelectrolyte with a densely packed hydrophobic core based on star amphiphiles represents an intriguing and novel case of compartmentalized microcapsules with an ability to simultaneously store different hydrophilic, charged, and hydrophobic

  16. Effect of layer-by-layer polyelectrolyte method on encapsulation of vanillin.

    PubMed

    Noshad, Mohammad; Mohebbi, Mohebbat; Shahidi, Fakhri; Koocheki, Arash

    2015-11-01

    The objective of this work was to microencapsulate vanillin by multilayer emulsion followed by spray drying, aiming to protect it and control its release. An electrostatic layer-by-layer deposition method was used to create the multilayered interfacial membranes around microcapsules with different compositions: (i) one-layer (soy protein isolate); (ii) two-layer (soy protein isolate - OSA starch); (iii) three-layer (soy protein isolate - OSA starch - Chitosan). The morphology of the microcapsules was analyzed by scanning electronic microscopy. The hygroscopicity, solubility, particle size, encapsulation efficiency, Fourier transform infrared spectroscopy and release into water (37°C and 80°C) were also examined. FTIR confirmed the interaction between the wall materials. All microcapsules were not very water-soluble or hygroscopic while three-layer microcapsules compared to one and two layer microcapsules have lower moisture content and predominantly shriveled surfaces. The results indicated it was possible to encapsulate vanillin with the techniques employed and that these protected the vanillin even at 80°C. The reduced solubility and low release rates indicated the enormous potential of the vehicle developed in controlling the release of the vanillin into the food and pharmaceuticals. PMID:26358552

  17. Influence of process parameters on the size distribution of PLA microcapsules prepared by combining membrane emulsification technique and double emulsion-solvent evaporation method.

    PubMed

    Liu, Rong; Ma, Guang-Hui; Wan, Yin-Hua; Su, Zhi-Guo

    2005-11-10

    Relatively uniform-sized biodegradable poly(lactide) (PLA) microcapsules with various sizes were successfully prepared by combining a glass membrane emulsification technique and water-in-oil-in-water (w1/o/w2) double emulsion-solvent evaporation method. A water phase was used as the internal water phase, a mixture solvent of dichloromethane (DCM) and toluene dissolving PLA and Arlacel 83 was used as the oil phase (o). These two solutions were emulsified by a homogenizer to form a w1/o primary emulsion. The primary emulsion was permeated through the uniform pores of a glass membrane into the external water phase by the pressure of nitrogen gas to form the uniform w1/o/w2 double emulsion droplets. Then, the solid polymer microcapsules were obtained by simply evaporating solvent. The influence of process parameters on the size distribution of PLA microcapsules was investigated, with an emphasis on the effect of oil-soluble emulsifier. A unique phenomenon was found that a large part of emulsifier could adsorb on the interface of internal water phase and oil phase, which suppressed its adsorption on the surface of glass membrane, and led to the successful preparation of uniform-sized double emulsion. Finally, by optimizing the process parameters, PLA microcapsules with various sizes having coefficient of variation (CV) value under 14.0% were obtained. Recombinant human insulin (rhI), as a model protein, was encapsulated into the microcapsules with difference sizes, and its encapsulation efficiency and cumulative release were investigated. The result suggested that the release behavior could be simply adjusted just by changing precisely the diameters of microcapsule, benefited from the membrane emulsification technique. PMID:16198091

  18. Multinode reconfigurable pipeline computer

    NASA Technical Reports Server (NTRS)

    Nosenchuck, Daniel M. (Inventor); Littman, Michael G. (Inventor)

    1989-01-01

    A multinode parallel-processing computer is made up of a plurality of innerconnected, large capacity nodes each including a reconfigurable pipeline of functional units such as Integer Arithmetic Logic Processors, Floating Point Arithmetic Processors, Special Purpose Processors, etc. The reconfigurable pipeline of each node is connected to a multiplane memory by a Memory-ALU switch NETwork (MASNET). The reconfigurable pipeline includes three (3) basic substructures formed from functional units which have been found to be sufficient to perform the bulk of all calculations. The MASNET controls the flow of signals from the memory planes to the reconfigurable pipeline and vice versa. the nodes are connectable together by an internode data router (hyperspace router) so as to form a hypercube configuration. The capability of the nodes to conditionally configure the pipeline at each tick of the clock, without requiring a pipeline flush, permits many powerful algorithms to be implemented directly.

  19. Coated dextrin microcapsules of amlodipine incorporable into orally disintegrating tablets for geriatric patients.

    PubMed

    Jang, Dong-Jin; Bae, Soo Kyung; Oh, Euichaul

    2014-10-01

    To improve oral absorption and patient compliance when using amlodipine, novel coated dextrin microcapsules incorporable into orally disintegrating tablets (ODT's) were investigated. Amlodipine-loaded dextrin microcapsules (ADM) were prepared by spray-drying a mixture of amlodipine free base dissolved in ethanol and aqueous dextrin solution. The ADM were suspended in Eudragit(®) EPO solution in ethanol and subsequently spray-dried to collect coated ADM (CADM). The ADM or CADM were blended with ODT excipients and then directly compressed into ODTs. The ADM and CADM used were both spherical with smooth surfaces and had mean particle sizes of 13.3 and 18.5μm, respectively. Amlodipine was dispersed in an amorphous state and was readily encapsulated within ADM or CADM. Unlike the ADM, the tableted CADM remained intact without rupture during tableting, which was consistent with no loss of ethanol (0.82%) entrapped in the ODTs containing the CADM (ODTs-CADM). The amlodipine content appeared to be uniformly maintained as designed in all the dextrin microcapsules and ODTs. The ODTs-CADM compressed with 3kp of hardness showed acceptable ODT characteristics: fast disintegration time (29.8s) and low friability (0.1%). Drug dissolution from the ODTs-CADM was much faster than that of amlodipine free base itself at both pH 1.2 and 6.8 over the tested time. CADM demonstrated significantly higher plasma concentrations (2.7 fold in AUC0-24h and 2.5 fold in Cmax) in SD rats than did amlodipine free base. These results indicate that CADM substantially increased the oral absorption of amlodipine and can be incorporated into ODTs while maintaining their original physicochemical features. The dextrin microcapsules coated using Eudragit(®) EPO may be applied to the development of an amlodipine ODT formulation for improving geriatric patient compliance. PMID:25458788

  20. The influence of 1-butanol and trisodium citrate ion on morphology and chemical properties of chitosan-based microcapsules during rigidification by alkali treatment.

    PubMed

    Chatterjee, Sudipta; Salaün, Fabien; Campagne, Christine

    2014-12-01

    Linseed oil which has various biomedical applications was encapsulated by chitosan (Chi)-based microcapsules in the development of a suitable carrier. Oil droplets formed in oil-in-water emulsion using sodium dodecyl sulfate (SDS) as emulsifier was stabilized by Chi, and microcapsules with multilayers were formed by alternate additions of SDS and Chi solutions in an emulsion through electrostatic interaction. No chemical cross-linker was used in the study and the multilayer shell membrane was formed by ionic gelation using Chi and SDS. The rigidification of the shell membrane of microcapsules was achieved by alkali treatment in the presence of a small amount of 1-butanol to reduce aggregation. A trisodium citrate solution was used to stabilize the charge of microcapsules by ionic cross-linking. Effects of butanol during alkali treatment and citrate in post alkali treatment were monitored in terms of morphology and the chemical properties of microcapsules. Various characterization techniques revealed that the aggregation was decreased and surface roughness was increased with layer formation. PMID:25474188

  1. Islet Transplantation and Encapsulation: An Update on Recent Developments

    PubMed Central

    Vaithilingam, Vijayaganapathy; Tuch, Bernard E.

    2011-01-01

    Human islet transplantation can provide good glycemic control in diabetic recipients without exogenous insulin. However, a major factor limiting its application is the recipient's need to adhere to life-long immunosuppression, something that has serious side effects. Microencapsulating human islets is a strategy that should prevent rejection of the grafted tissue without the need for anti-rejection drugs. Despite promising studies in various animal models, the encapsulated human islets so far have not made an impact in the clinical setting. Many non-immunological and immunological factors such as biocompatibility, reduced immunoprotection, hypoxia, pericapsular fibrotic overgrowth, effects of the encapsulation process and post-transplant inflammation hamper the successful application of this promising technology. In this review, strategies are discussed to overcome the above-mentioned factors and to enhance the survival and function of encapsulated insulin-producing cells, whether in islets or surrogate β-cells. Studies at our center show that barium alginate microcapsules are biocompatible in rodents, but not in humans, raising concerns over the use of rodents to predict outcomes. Studies at our center also show that the encapsulation process had little or no effect on the cellular transcriptome of human islets and on their ability to function either in vitro or in vivo. New approaches incorporating further modifications to the microcapsule surface to prevent fibrotic overgrowth are vital, if encapsulated human islets or β-cell surrogates are to become a viable therapy option for type 1 diabetes in humans. PMID:21720673

  2. Effect of wall material on the antioxidant activity and physicochemical properties of Rubus fruticosus juice microcapsules.

    PubMed

    Díaz, Dafne I; Beristain, Cesar I; Azuara, Ebner; Luna, Guadalupe; Jimenez, Maribel

    2015-01-01

    Blackberry (Rubus fruticosus) juice possesses compounds with antioxidant activity, which can be protected by different biopolymers used in the microencapsulation. Therefore, the effects of cell wall material including maltodextrin (MD), Arabic gum (GA) and whey protein concentrate (WPC) were evaluated on the physicochemical and antioxidant properties of encapsulated blackberries using a spray-drying technique. Anthocyanin concentration, polymeric colour, total polyphenols, radical scavenging activity of the 1,1-diphenyl-2-picrilhydrazil radical, reducing power and the stability at different storage conditions were evaluated. GA and MD conferred a similar protection to the antioxidant compounds when the microcapsules were stored at low water activities (aw < 0.515) in contrast to at a high moisture content (aw > 0.902), whereas WPC presented a high protection. Therefore, the selection of the best wall material for blackberry juice encapsulation depends of the conditions of storage of the powder. PMID:26006741

  3. N, N-diethyl-m-toluamide-containing microcapsules for bio-cloth finishing.

    PubMed

    Fei, Bin; Xin, John H

    2007-07-01

    To obtain long-duration protection from mosquitoes using insect repellent N, N-diethyl-m-toluamide (DEET), this compound was incapsulated in situ during the graft copolymerization of butyl acrylate onto chitosan in an aqueous solution. Morphology of microcapsules was characterized by scanning electron microscopy, scanning probe microscopy, and transmission electron microscopy. This morphology supported successful encapsulation of DEET into polymer capsules. The encapsulation ratio of DEET was greater than 33%, as estimated from thermo-gravimetric results. The aqueous emulsions were applied to cotton textiles by spraying. Treated cloth showed high bactericidal activity against Staphylococcus aureus. Mosquito repellency of the bio-cloth was evaluated with Aedes albopictus. The 90% effective dose of emulsions on textiles was compared with that of DEET in ethanol. A time profile showed that the repellency of an optimized emulsion was 100% after eight hours, and partially preserved even after exposure to air for 48 hours. PMID:17620630

  4. Effect of microencapsulation of Lactobacillus plantarum 25 into alginate/chitosan/alginate microcapsules on viability and cytokine induction.

    PubMed

    Jiang, Tao; Kim, You-Kyoung; Singh, Bijay; Kang, Sang-Kee; Choi, Yun-Jaie; Cho, Chong-Su

    2013-08-01

    Lactobacillus plantarum 25 (LP25) encapsulated into alginate/chitosan/alginate (ACA) microcapsules (LP25-ACA MCs) prepared by an extrusion methods were characterized to assess their efficacy in oral delivery. The particle sizes of LP25-ACA MCs were 1.11 +/- 0.32 mm. The loading content of LP25 was 1.11 x 10(7) colony forming unit (cfu)/microcapsule and encapsulation efficiency was above 98%. The viability of LP25 in ACA MCs was more than 65% in simulated gastric fluid (SGF, pH 2.0) and 75% in simulated small intestinal fluid (SIF, pH 7.2) up to 2 h. Encapsulated LP25 were completely released from LP25-ACA MCs in SIF and simulated colon fluid (SCF, pH 6.0) within 12 h and 8 h respectively. The viability of LP25 in ACA MCs till 5 weeks was above 58%, whereas viability of free LP25 stored at room temperature up to 5 weeks was zero. Besides, LP25-ACA MCs induced the secretion of tumor necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6) from macrophages and dendritic cells showing the immunomodulatory effect of LP25. These findings demonstrate that the encapsulation of LP25 by ACA is a suitable strategy for oral delivery of probiotics. PMID:23882756

  5. Magnetite (Fe3O4) microcapsules prepared using a glass membrane and solvent removal.

    PubMed

    Omi, S; Kanetaka, A; Shimamori, Y; Supsakulchai, A; Nagai, M; Ma, G H

    2001-01-01

    Fine magnetite powders dispersed in polymer solution were encapsulated from an oil-in-water emulsion prepared by an emulsification process employing a porous glass membrane and subsequent evaporation of the solvent. Styrene-based copolymers were dissolved in a magnetic fluid, and then continuously pushed through the pores of glass membrane into the aqueous phase, which had dissolved polyvinyl alcohol (PVA) and sodium dodecyl sulphate (SDS) as a mixed stabilizer. P(styrene-co-acrylic acid) (PS-AA), P(stryrene-co-butyl acrylate) (PS-BA) and styrene-butadiene rubber (SBR) were dissolved in the specially ordered magnetite fluid (25 wt% magnetite dispersed in toluene) separately or as a mixture, and uniform droplets suspending the magnetic particles were obtained. After the evaporation of toluene, PS-AA capsules retained a spherical shape and uniformity, whereas PS-AA/PS-BA capsules revealed a creased surface and broader size distribution. The microcapsules entrapped 30-40 wt% of magnetite, and the encapsulation yield of magnetite was 20-40%. Glass membranes with 9.5, 5.25 and 1.42 microm pore size were employed and 5-40 microm microcapsules were obtained depending on the pore size. When magnetite suspended in chloroform was used, magnetite capsules with broader size distributions were obtained because of the sticking of the droplets to the membrane wall. The advantage of the membrane emulsification which provides uniform sized droplets was lost. PMID:11695639

  6. A 'microfluidic pinball' for on-chip generation of Layer-by-Layer polyelectrolyte microcapsules.

    PubMed

    Kantak, Chaitanya; Beyer, Sebastian; Yobas, Levent; Bansal, Tushar; Trau, Dieter

    2011-03-21

    Inspired by the game of "pinball" where rolling metal balls are guided by obstacles, here we describe a novel microfluidic technique which utilizes micropillars in a flow channel to continuously generate, encapsulate and guide Layer-by-Layer (LbL) polyelectrolyte microcapsules. Droplet-based microfluidic techniques were exploited to generate oil droplets which were smoothly guided along a row of micropillars to repeatedly travel through three parallel laminar streams consisting of two polymers and a washing solution. Devices were prototyped in PDMS and generated highly monodisperse and stable 45±2 µm sized polyelectrolyte microcapsules. A total of six layers of hydrogen bonded polyelectrolytes (3 bi-layers) were adsorbed on each droplet within <3 minutes and a fluorescent intensity measurement confirmed polymer film deposition. AFM analysis revealed the thickness of each polymer layer to be approx. 2.8 nm. Our design approach not only provides a faster and more efficient alternative to conventional LbL deposition techniques, but also achieves the highest number of polyelectrolyte multilayers (PEMs) reported thus far using microfluidics. Additionally, with our design, a larger number of PEMs can be deposited without adding any extra operational or interfacial complexities (e.g. syringe pumps) which are a necessity in most other designs. Based on the aforementioned advantages of our device, it may be developed into a great tool for drug encapsulation, or to create capsules for biosensing where deposition of thin nanofilms with controlled interfacial properties is highly required. PMID:21218225

  7. Synthetic Quorum Sensing and Induced Aggregation in Model Microcapsule Colonies with Repressilator Feedback

    NASA Astrophysics Data System (ADS)

    Shum, Henry; Yashin, Victor; Balazs, Anna

    We model a system of synthetic microcapsules that communicate chemically by releasing nanoparticles or signaling molecules. These signaling species bind to receptors on the shells of capsules and modulate the target shell's permeability, thereby controlling nanoparticle release from the target capsule. Using the repressilator regulatory network motif, whereby three species suppress the production of the next in a cyclic fashion, we show that large amplitude oscillations in nanoparticle release can emerge when many capsules are close together. This exemplifies quorum sensing, which is the ability of cells to gauge their population density and collectively initiate a new behavior once a critical density is reached. We present a physically realizable model in which the oscillations exhibited in crowded populations induce aggregation of the microcapsules, mimicking complex biological behavior of the slime mold Dictyostelium discoideum with only simple, synthetic components. We also show that the clusters can be dispersed and reformed repeatedly and controllably by addition of chemical stimuli, demonstrating possible applications in creating reconfigurable or programmable materials.

  8. Hydrogel-based encapsulation of biological, functional tissue: fundamentals, technologies and applications

    NASA Astrophysics Data System (ADS)

    Zimmermann, H.; Ehrhart, F.; Zimmermann, D.; Müller, K.; Katsen-Globa, A.; Behringer, M.; Feilen, P. J.; Gessner, P.; Zimmermann, G.; Shirley, S. G.; Weber, M. M.; Metze, J.; Zimmermann, U.

    2007-12-01

    Replacing dysfunctional endocrine cells or tissues (e.g. islets, parathyroid tissue) by functional, foreign material without using immunosuppressives could soon become reality. Immunological reactions are avoided by encapsulating cells/tissues in hydrogel (e.g. alginate) microcapsules, preventing interaction of the enclosed material with the host’s immune system while permitting the unhindered passage of nutrients, oxygen and secreted therapeutic factors. Detailed investigations of the physical, physico-chemical and immunological parameters of alginate-based microcapsules have led recently to the development of a novel class of cell-entrapping microcapsules that meet the demands of biocompatibility, long-term integrity and function. This together with the development of ‘good medical practice’ microfluidic chip technology and of advanced cryopreservation technology for generation and storage of immunoisolated transplants will bring cell-based therapy to clinics and the market.

  9. Encapsulation of folic acid in food hydrocolloids through nanospray drying and electrospraying for nutraceutical applications.

    PubMed

    Pérez-Masiá, Rocío; López-Nicolás, Rubén; Periago, Maria Jesús; Ros, Gaspar; Lagaron, Jose M; López-Rubio, Amparo

    2015-02-01

    In this work, two different technologies (electrospraying and nanospray drying) were evaluated for the encapsulation of folic acid using both a whey protein concentrate (WPC) matrix and a commercial resistant starch. The morphology of the capsules, molecular organization of the matrices upon encapsulation, encapsulation efficiency, and stability of the folic acid within the capsules under different storage conditions and upon thermal exposure were studied. Results showed that spherical nano-, submicro- and microcapsules were obtained through both techniques, although electrospraying led to smaller capsule sizes and to an enhanced control over their size distribution. Greater encapsulation efficiency was observed using WPC as encapsulating matrix, probably related to interactions between the protein and folic acid which favoured the incorporation of the bioactive. The best results in terms of bioactive stabilization in the different conditions assayed were also obtained for the WPC capsules, although both materials and encapsulation techniques led to improved folic acid stability, especially under dry conditions. PMID:25172691

  10. Reconfigurable Processing Module

    NASA Technical Reports Server (NTRS)

    Somervill, Kevin; Hodson, Robert; Jones, Robert; Williams, John

    2005-01-01

    To accommodate a wide spectrum of applications and technologies, NASA s Exploration System's Missions Directorate has called for reconfigurable and modular technologies to support future missions to the moon and Mars. In response, Langley Research Center is leading a program entitled Reconfigurable Scaleable Computing (RSC) that is centered on the development of FPGA-based computing resources in a stackable form factor. This paper details the architecture and implementation of the Reconfigurable Processing Module (RPM), which is the key element of the RSC system. The RPM is an FPGA-based, space-qualified printed circuit assembly leveraging terrestrial/commercial design standards into the space applications domain. The form factor is similar to, and backwards compatible with, the PCI-104 standard utilizing only the PCI interface. The size is expanded to accommodate the required functionality while still better than 30% smaller than a 3U CompactPCI(TradeMark)card and without the overhead of the backplane. The architecture is built around two FPGA devices, one hosting PCI and memory interfaces, and another hosting mission application resources; both of which are connected with a high-speed data bus. The PCI interface FPGA provides access via the PCI bus to onboard SDRAM, flash PROM, and the application resources; both configuration management as well as runtime interaction. The reconfigurable FPGA, referred to as the Application FPGA - or simply "the application" - is a radiation-tolerant Xilinx Virtex-4 FX60 hosting custom application specific logic or soft microprocessor IP. The RPM implements various SEE mitigation techniques including TMR, EDAC, and configuration scrubbing of the reconfigurable FPGA. Prototype hardware and formal modeling techniques are used to explore the performability trade space. These models provide a novel way to calculate quality-of-service performance measures while simultaneously considering fault-related behavior due to SEE soft errors.

  11. Fatty acid composition in double and multilayered microcapsules of ω-3 as affected by storage conditions and type of emulsions.

    PubMed

    Jiménez-Martín, Estefanía; Antequera Rojas, Teresa; Gharsallaoui, Adem; Ruiz Carrascal, Jorge; Pérez-Palacios, Trinidad

    2016-03-01

    Spray-dried microcapsules from double (DM) and multilayered (MM) fish oil emulsions were produced to evaluate the effect of type of emulsion on the fatty acid composition during the microencapsulation process and after one month of storage at refrigeration (4°C) and room (20°C) temperature. Encapsulation efficiency, loading and loading efficiency were significantly higher in MM than in DM. C20:5 n-3 (EPA) and C22:6 n-3 (DHA) showed higher proportions in MM than in DM. Some differences in microstructural features were detected, with DM showing cracks and pores. The influence of the storage was significant, decreasing the content of polyunsaturated fatty acids in both MM and DM, above all at 20°C. This decrease was more notable in DM. Multilayered emulsions are more suitable to encapsulate fish oil in terms of quantity of encapsulated oil, microstructure of the microcapsules and protection of fatty acids, especially EPA and DHA, during storage. PMID:26471582

  12. Fibrous microcapsules and methods of assembly and use thereof

    DOEpatents

    Stupp, Samuel; Rozkiewicz, Dorota

    2015-01-27

    The present invention relates to assembly of peptide amphiphiles and biopolymers into fibrous microcapsules, and uses thereof. In particular, the present invention provides devices, compositions, and methods for interfacial self-assembly of peptide amphiphiles and biopolyments into fibrous microcapsules, and uses thereof.

  13. Preparation and comparative release characteristics of three anthocyanin encapsulation systems.

    PubMed

    Oidtmann, Johannes; Schantz, Markus; Mäder, Karsten; Baum, Matthias; Berg, Sonja; Betz, Michael; Kulozik, Ulrich; Leick, Sabine; Rehage, Heinz; Schwarz, Karin; Richling, Elke

    2012-01-25

    Bilberries (Vaccinium myrtillus L.) and their major polyphenolic constituents, anthocyanins, have preventive activities inter alia against colon cancer and inflammatory bowel diseases. However, anthocyanins are sensitive to environmental conditions; thus their bioavailability in the gastrointestinal tract is an important determinant of their in vivo activity. In the study reported here, the potential benefits of encapsulating an anthocyanin rich bilberry extract (BE) on anthocyanin stability were investigated. Nonencapsulated BE and three different BE loaded microcapsule systems were incubated in simulated gastric fluid (SGF) and fed state simulated intestinal fluid (FeSSIF). After exposure to these media, released anthocyanins were identified and quantified by HPLC with UV/Vis detection. Although a rapid release of anthocyanins was observed within the first 20 min, encapsulation of anthocyanins doubled the amount of available anthocyanins after 150 min of incubation. These results illustrate the ability of encapsulation to inhibit early degradation of anthocyanins in the intestinal system. PMID:22224434

  14. Assembly-Controlled Permeability of Layer-by-Layer Polymeric Microcapsules Using a Tapered Fluidized Bed.

    PubMed

    Noi, Ka Fung; Roozmand, Ali; Björnmalm, Mattias; Richardson, Joseph J; Franks, George V; Caruso, Frank

    2015-12-23

    Nano- and microcapsules engineered through layer-by-layer (LbL) assembly are finding an increasingly large number of applications as catalysts, electrochemical biosensors, bioreactors, artificial cells and drug delivery vehicles. While centrifugation-based LbL assembly is the most common method for coating template particles and preparing capsules, it is a batch process and requires frequent intervention that renders the system challenging to automate and scale up. Here, we report the use of a tapered fluidized bed (TFB) for the preparation of multilayered polymer capsules. This is a significant improvement over our recent approach of fluidizing particles in cylindrical fluidized beds (CFB) for LbL assembly. We demonstrate that TFB is compatible with particles <3 μm in diameter (an order-of-magnitude improvement compared with CFB), which can be fluidized with minimal entrainment. Additionally, layering materials were expanded to include both electrostatic and hydrogen-bonding polymer pairs (e.g., poly(allylamine hydrochloride) (PAH) and poly(styrenesulfonate) (PSS), and thiol-modified poly(methacrylic acid) (PMASH) and poly(N-vinylpyrrolidone) (PVPON), respectively). Finally, differences between capsules prepared via centrifugation-based and TFB LbL assembly were investigated. The obtained TFB microcapsules demonstrate increased film thickness and roughness compared with those prepared using centrifugation-based LbL assembly. Furthermore, PMASH microcapsules exhibit lower swelling and permeability when prepared via TFB LbL assembly compared with centrifugation-based LbL assembly due to enhanced multilayer deposition, entanglement, and cross-linking. Therefore, polymeric capsules fabricated via TFB LbL assembly may be useful for encapsulation and retention of relatively low molecular weight (∼20 kDa) hydrophilic biomacromolecules to passively or responsively release the payload for drug delivery applications. PMID:26651354

  15. Reconfigurable nanomechanical photonic metamaterials

    NASA Astrophysics Data System (ADS)

    Zheludev, Nikolay I.; Plum, Eric

    2016-01-01

    The changing balance of forces at the nanoscale offers the opportunity to develop a new generation of spatially reconfigurable nanomembrane metamaterials in which electromagnetic Coulomb, Lorentz and Ampère forces, as well as thermal stimulation and optical signals, can be engaged to dynamically change their optical properties. Individual building blocks of such metamaterials, the metamolecules, and their arrays fabricated on elastic dielectric membranes can be reconfigured to achieve optical modulation at high frequencies, potentially reaching the gigahertz range. Mechanical and optical resonances enhance the magnitude of actuation and optical response within these nanostructures, which can be driven by electric signals of only a few volts or optical signals with power of only a few milliwatts. We envisage switchable, electro-optical, magneto-optical and nonlinear metamaterials that are compact and silicon-nanofabrication-technology compatible with functionalities surpassing those of natural media by orders of magnitude in some key design parameters.

  16. Reconfigurable nanomechanical photonic metamaterials.

    PubMed

    Zheludev, Nikolay I; Plum, Eric

    2016-01-01

    The changing balance of forces at the nanoscale offers the opportunity to develop a new generation of spatially reconfigurable nanomembrane metamaterials in which electromagnetic Coulomb, Lorentz and Ampère forces, as well as thermal stimulation and optical signals, can be engaged to dynamically change their optical properties. Individual building blocks of such metamaterials, the metamolecules, and their arrays fabricated on elastic dielectric membranes can be reconfigured to achieve optical modulation at high frequencies, potentially reaching the gigahertz range. Mechanical and optical resonances enhance the magnitude of actuation and optical response within these nanostructures, which can be driven by electric signals of only a few volts or optical signals with power of only a few milliwatts. We envisage switchable, electro-optical, magneto-optical and nonlinear metamaterials that are compact and silicon-nanofabrication-technology compatible with functionalities surpassing those of natural media by orders of magnitude in some key design parameters. PMID:26740040

  17. Probiotic Ferulic Acid Esterase Active Lactobacillus fermentum NCIMB 5221 APA Microcapsules for Oral Delivery: Preparation and in Vitro Characterization.

    PubMed

    Tomaro-Duchesneau, Catherine; Saha, Shyamali; Malhotra, Meenakshi; Coussa-Charley, Michael; Kahouli, Imen; Jones, Mitchell L; Labbé, Alain; Prakash, Satya

    2012-01-01

    Probiotics possess potential therapeutic and preventative effects for various diseases and metabolic disorders. One important limitation for the oral delivery of probiotics is the harsh conditions of the upper gastrointestinal tract (GIT) which challenge bacterial viability and activity. One proposed method to surpass this obstacle is the use of microencapsulation to improve the delivery of bacterial cells to the lower GIT. The aim of this study is to use alginate-poly-L-lysine-alginate (APA) microcapsules to encapsulate Lactobacillus fermentum NCIMB 5221 and characterize its enzymatic activity and viability through a simulated GIT. This specific strain, in previous research, was characterized for its inherent ferulic acid esterase (FAE) activity which could prove beneficial in the development of a therapeutic for the treatment and prevention of cancers and metabolic disorders. Our findings demonstrate that the APA microcapsule does not slow the mass transfer of substrate into and that of the FA product out of the microcapsule, while also not impairing bacterial cell viability. The use of simulated gastrointestinal conditions led to a significant 2.5 log difference in viability between the free (1.10 × 104 ± 1.00 × 103 cfu/mL) and the microencapsulated (5.50 × 106 ± 1.00 × 105 cfu/mL) L. fermentum NCIMB 5221 following exposure. The work presented here suggests that APA microencapsulation can be used as an effective oral delivery method for L. fermentum NCIMB 5221, a FAE-active probiotic strain. PMID:24288090

  18. Novel reduction of Cr(VI) from wastewater using a naturally derived microcapsule loaded with rutin-Cr(III) complex.

    PubMed

    Qi, Yun; Jiang, Meng; Cui, Yuan-Lu; Zhao, Lin; Liu, Shejiang

    2015-03-21

    The harmfulness of carcinogenic hexavalent chromium (Cr(VI)) is dramatically decreased when Cr(VI) is reduced to trivalent chromium (Cr(III)). Rutin, a natural flavonoid, exhibits excellent antioxidant activity by coordinating metal ions. In this study, a complex containing rutin and Cr(III) (rutin-Cr(III)) was synthesized and characterized. The rutin-Cr(III) complex was much easier to reduce than rutin. The reduction of the rutin-Cr(III) complex was highly pH-dependent, with 90% of the Cr(VI) being reduced to Cr(III) in 2h under optimal conditions. A biodegradable, sustained-release system encapsulating the rutin-Cr(III) complex in a alginate-chitosan microcapsule (rutin-Cr(III) ACMS) was also evaluated, and the reduction of Cr(VI) was assessed. This study also demonstrated that low-pH solutions increased the reduction rate of Cr(VI). The environmentally friendly microcapsules can reduce Cr(VI) for prolonged periods of time and can easily biodegrade after releasing the rutin-Cr(III) complex. Given the excellent performance of rutin-Cr(III) ACMS, the microcapsule system represents an effective system for the remediation of Cr(VI) pollution. PMID:25528232

  19. Production of BSA-loaded alginate microcapsules: influence of spray dryer parameters on the microcapsule characteristics and BSA release.

    PubMed

    Benchabane, Samir; Subirade, Muriel; Vandenberg, Grant W

    2007-09-01

    The aim of this study was to optimize the production of BSA-loaded alginate microcapsules by spray drying and to study the release of bovine serum albumin fraction V (BSA) under gastric simulated conditions. Microcapsule yield, BSA release, microcapsule size and size distribution were characterized following the application of different production parameters including inlet air temperature, inlet air pressure and liquid feed rate. The microcapsules were incubated in 0.1 N HCl and BSA release was quantified over time. The yields were higher with the pressure of 3 bar compared to 4 bar and with a feed rate of 0.45 vs. 0.2 ml s(-1). A high feed rate (0.45 vs. 0.2 ml s(-1)) allows one to obtain microcapsules with a low BSA release (p = 0.0327). The increase of the atomizer inlet temperature leads to microcapsules with a higher BSA release (p = 0.0230). A higher air pressure of 4 bar compared to 3 bar resulted in a lower microcapsule size (2.55 vs. 2.80 microm) and led to a narrower size distribution (0.92 vs. 1.07). In conclusion, the spray dryer parameters influenced the alginate microcapsule characteristics as well as subsequent protein release into a simulated gastric medium. PMID:17654176

  20. Self-Reconfigurable Robots

    SciTech Connect

    HENSINGER, DAVID M.; JOHNSTON, GABRIEL A.; HINMAN-SWEENEY, ELAINE M.; FEDDEMA, JOHN T.; ESKRIDGE, STEVEN E.

    2002-10-01

    A distributed reconfigurable micro-robotic system is a collection of unlimited numbers of distributed small, homogeneous robots designed to autonomously organize and reorganize in order to achieve mission-specified geometric shapes and functions. This project investigated the design, control, and planning issues for self-configuring and self-organizing robots. In the 2D space a system consisting of two robots was prototyped and successfully displayed automatic docking/undocking to operate dependently or independently. Additional modules were constructed to display the usefulness of a self-configuring system in various situations. In 3D a self-reconfiguring robot system of 4 identical modules was built. Each module connects to its neighbors using rotating actuators. An individual component can move in three dimensions on its neighbors. We have also built a self-reconfiguring robot system consisting of 9-module Crystalline Robot. Each module in this robot is actuated by expansion/contraction. The system is fully distributed, has local communication (to neighbors) capabilities and it has global sensing capabilities.

  1. One-Step Microfluidic Generation of Pre-Hatching Embryo-Like Core-Shell Microcapsules for Miniaturized 3D Culture of Pluripotent Stem Cells

    PubMed Central

    Agarwal, Pranay; Zhao, Shuting; Bielecki, Peter; Rao, Wei; Choi, Jung K.; Zhao, Yi; Yu, Jianhua; Zhang, Wujie; He, Xiaoming

    2013-01-01

    A novel core-shell microcapsule system is developed in this study to mimic the miniaturized 3D architecture of pre-hatching embryos with an aqueous liquid core of embryonic cells and a hydrogel-shell of zona pellucida. This is done by microfabricating a non-planar microfluidic flow-focusing device that enables one-step generation of microcapsules with an alginate hydrogel shell and an aqueous liquid core of cells from two aqueous fluids. Mouse embryonic stem (ES) cells encapsulated in the liquid core are found to survive well (> 92 %). Moreover, ~ 20 ES cells in the core can proliferate to form a single ES cell aggregate in each microcapsule within 7 days while at least a few hundred cells are usually needed by the commonly used hanging-drop method to form an embryoid body (EB) in each hanging drop. Quantitative RT-PCR analyses show significantly higher expression of pluripotency marker genes in the 3D aggregated ES cells compared to the cells under 2D culture. The aggregated ES cells can be efficiently differentiated into beating cardiomyocytes using a small molecule (cardiogenol C) without complex combination of multiple growth factors. Taken together, the novel 3D microfluidic and pre-hatching embryo-like microcapsule systems are of importance to facilitate in vitro culture of pluripotent stem cells for their ever-increasing use in modern cell-based medicine. PMID:24113543

  2. Fabrication of carbon microcapsules containing silicon nanoparticles-carbon nanotubes nanocomposite by sol-gel method for anode in lithium ion battery

    NASA Astrophysics Data System (ADS)

    Bae, Joonwon

    2011-07-01

    Carbon microcapsules containing silicon nanoparticles (Si NPs)-carbon nanotubes (CNTs) nanocomposite (Si-CNT@C) have been fabricated by a surfactant mediated sol-gel method followed by a carbonization process. Silicon nanoparticles-carbon nanotubes (Si-CNT) nanohybrids were produced by a wet-type beadsmill method. To obtain Si-CNT nanocomposites with spherical morphologies, a silica precursor (tetraethylorthosilicate, TEOS) and polymer (PMMA) mixture was employed as a structure-directing medium. Thus the Si-CNT/Silica-Polymer microspheres were prepared by an acid catalyzed sol-gel method. Then a carbon precursor such as polypyrrole (PPy) was incorporated onto the surfaces of pre-existing Si-CNT/silica-polymer to generate Si-CNT/Silica-Polymer@PPy microspheres. Subsequent thermal treatment of the precursor followed by wet etching of silica produced Si-CNT@C microcapsules. The intermediate silica/polymer must disappear during the carbonization and etching process resulting in the formation of an internal free space. The carbon precursor polymer should transform to carbon shell to encapsulate remaining Si-CNT nanocomposites. Therefore, hollow carbon microcapsules containing Si-CNT nanocomposites could be obtained (Si-CNT@C). The successful fabrication was confirmed by scanning electron microscopy (SEM) and X-ray diffraction (XRD). These final materials were employed for anode performance improvement in lithium ion battery. The cyclic performances of these Si-CNT@C microcapsules were measured with a lithium battery half cell tests.

  3. One-step fabrication of triple-layered microcapsules by a tri-axial flow focusing device for microencapsulation of soluble drugs and imaging agents

    NASA Astrophysics Data System (ADS)

    Yuan, Shuai; Wu, Qiang; Lei, Fan; Li, Guangbin; Si, Ting; Xu, Ronald X.

    2016-04-01

    In this work, the microencapsulation of water-soluble drug (doxorubicin, Dox) and imaging agent (perfluorocarbon, PFC) is performed by a novel liquid driven tri-axial flow focusing (LDTFF) device. The formation of stable triple-layered cone-jet mode can be observed in the simple well-assembled LDTFF device, providing an easy approach to fabricate mono-disperse triple-layered microcapsules with high encapsulation efficiency, high throughput and low cost in just one step. The fluorescence images show that the microcapsules have a satisfactory core-shell structure. The SEM micrographs show spherical and smooth surface views of the triple-layered microcapsules after being stirred 72h to remove the organic solvent totally. The results of thermo-responsive release experiments of the produced triple-layered microcapsules show these multifunctional capsules can be well stimulated when the environment temperature is beyond 55 degree centigrade. In a word, this novel approach has a great potential in applications such as drug delivery and image-guided therapy.

  4. Mechanistic study of carvacrol processing and stabilization as glassy solid solution and microcapsule.

    PubMed

    Tackenberg, Markus W; Geisthövel, Carola; Marmann, Andreas; Schuchmann, Heike P; Kleinebudde, Peter; Thommes, Markus

    2015-01-30

    Essential oils and other liquid active pharmaceutical ingredients (APIs) are frequently microencapsulated to improve shelf life, handling, and for tailoring release. A glassy solid solution (GSS), a single-phase system, where the excipient is plasticized by the API, could be an alternative formulation system. Thus this study focuses on the investigation of two formulation strategies using carvacrol as a model compound, namely a microcapsule (MC) and a glassy solid solution (GSS). Applying the solubility parameter approach, polyvinylpyrrolidone (PVP) was chosen as a suitable matrix material for a GSS system, whereas maltodextrin and sucrose served as excipients for a microcapsule (MC) system. Differential scanning calorimetry (DSC) measurements of the excipients' glass transition temperatures and the melting point of carvacrol verified plasticizing properties of carvacrol on PVP. Batch mixing processes, as preliminary experiments for future extrusion processes, were performed to prepare GSSs and MCs with various amounts of carvacrol, followed by crushing and sieving. Maximally 4.5% carvacrol was encapsulated in the carbohydrate material, whereas up to 16.3% were stabilized as GSS, which is an outstanding amount. However, grinding of the samples led to a loss of up to 30% of carvacrol. PMID:25498156

  5. Effects of sequentially released BMP-2 and BMP-7 from PELA microcapsule-based scaffolds on the bone regeneration

    PubMed Central

    Li, Xialin; Yi, Weihong; Jin, Anmin; Duan, Yang; Min, Shaoxiong

    2015-01-01

    Osteoinductive biomaterials are helpful for the therapy of large bone defects and provide an alternative to autogenous bone and allografts. Recently, multiple growth factors are delivered to mimic the natural process of bone healing in the bone tissue engineering. Herein, we investigated the effects of sequential released bone morphogenetic protein-2 (BMP-2) and bone morphogenetic protein-7 (BMP-7) from polylactide-poly (ethylene glycol)-polylactide (PELA) microcapsule-based scaffolds on the bone regeneration. Through improving the double emulsion/solvent evaporation technique, BMP-7 was encapsulated in PELA microcapsules, to the surface of which BMP-2 was attached. Then, the scaffold (BMP-2/PELA/BMP-7) was fused by these microcapsules with dichloromethane vapor method. In vitro, it sequentially delivered bioactive BMP-2 and BMP-7 and partially imitated the profile of BMPs expression during the fracture healing. To determine the bioactivity of released BMP-2 and BMP-7, alkaline phosphatase (AKP) activity was analyzed in MC3T3-E1 cells. When compared with simple BMP-2 plus BMP-7group and pure PELA group, the AKP activity in BMP-2/PELA/BMP-7 group significantly increased. MTT assay indicated the BMP-loaded PELA scaffold had no adverse effects on cell activity. In addition, the effects of BMP-loaded scaffolds were also investigated in a rat femoral defect model by micro-computed tomographic (mCT) and histological examination. At 4 and 8 weeks post-implantation, BMP-2/PELA/BMP-7 significantly promoted osteogenesis as compared to other groups. The scaffold underwent gradual degradation and replacement by new bones at 8 weeks. Our findings suggest that the sequential release of BMP-2 and BMP-7from PELA microcapsule-based scaffolds is promising for the therapy of bone defects. PMID:26396672

  6. Impact of crystalline form changing on behavior of microcapsules prepared from three-component gel system.

    PubMed

    Fenyvesi, Zsófia; Ashour, Khaled Omaru A; Zelkó, Romána; Müller, Ulrich; Antal, István; Klebovich, Imre; Marton, Sylvia

    2010-12-01

    In this paper, the effect of anhydrous-monohydrate process-induced transformation of theophylline was examined in microcapsules produced by in situ gelation method using sodium alginate, hydroxypropylmethylcellulose and hydroxyethylcellulose. Films produced from gel were applied to characterize the changes by NIR spectroscopy, X-ray, DSC method and stereomicroscopy because it is easier to study that in films in the case of gel systems used in situ gelation process. The properties of end-product are influenced by the swelling ability, equilibrium water uptake, release profile and encapsulation efficiency. Water penetration and drug release were evaluated by Davidson-Peppas and Korsmeyer-Peppas models. The ex tempore formed monohydrate crystals were smaller and built into the matrix structure in a greater extent. Increased drug release, matrix erosion and diffuse reflectance values at 1470 and 1950 nm were observed added theophylline later into the gel because of developing a denser structure. PMID:19848611

  7. Effect of chitosan concentration on PLGA microcapsules for controlled release and stability of resveratrol.

    PubMed

    Sanna, Vanna; Roggio, Anna Maria; Pala, Nicolino; Marceddu, Salvatore; Lubinu, Giuseppe; Mariani, Alberto; Sechi, Mario

    2015-01-01

    The polyphenols as nutraceutical and therapeutic agents are gaining growing interest for their beneficial effects and potential in human health. In order to protect their scaffolds and functionality, and to improve the bioavailability, the microencapsulation can represent a promising strategy. This study reports on the formulation of the natural resveratrol (RSV) into microcapsules (MCs) prepared by using different concentrations of chitosan (CS) and poly(D,L-lactic-co-glycolic acid) (PLGA) as polymeric matrix. MCs were prepared by W/O/W double emulsion method and characterized in terms of morphology, size, encapsulation efficiency, physicochemical and thermal properties. RSV release behavior from MCs was evaluated under simulated gastrointestinal fluids, and the long term stability was monitored at different storage conditions. MCs resulted to have spherical shape and different morphology, with size ranging from 11 to 20 μm, and encapsulation efficiencies of 40-52%, depending on the CS concentration. Moreover, MCs containing CS exhibited a significant lower release of RSV than those containing only PLGA. Furthermore, all tested formulations were able to ensure a good retention and stability of encapsulated RSV until 6 months. In summary, CS/PLGA MCs can be proposed as an attractive delivery system to control the release and long term protection of RSV. PMID:25220789

  8. Multilayered Polyelectrolyte Microcapsules: Interaction with the Enzyme Cytochrome C Oxidase

    PubMed Central

    Pastorino, Laura; Dellacasa, Elena; Noor, Mohamed R.; Soulimane, Tewfik; Bianchini, Paolo; D'Autilia, Francesca; Antipov, Alexei; Diaspro, Alberto; Tofail, Syed A. M.; Ruggiero, Carmelina

    2014-01-01

    Cell-sized polyelectrolyte capsules functionalized with a redox-driven proton pump protein were assembled for the first time. The interaction of polyelectrolyte microcapsules, fabricated by electrostatic layer-by-layer assembly, with cytochrome c oxidase molecules was investigated. We found that the cytochrome c oxidase retained its functionality, that the functionalized microcapsules interacting with cytochrome c oxidase were permeable and that the permeability characteristics of the microcapsule shell depend on the shell components. This work provides a significant input towards the fabrication of an integrated device made of biological components and based on specific biomolecular functions and properties. PMID:25372607

  9. Non-Spherical Microcapsules for Increased Core Content Volume Delivery

    NASA Technical Reports Server (NTRS)

    Oliva-Buisson, Yvette J.

    2014-01-01

    The goal of this project was to advance microencapsulation from the standard spherical microcapsule to a non-spherical, high-aspect ratio (HAR), elongated microcapsule. This was to be accomplished by developing reproducible methods of synthesizing or fabricating robust, non-spherical, HAR microcapsules. An additional goal of this project was to develop the techniques to the point where scale-up of these methods could be examined. Additionally, this project investigated ways to apply the microencapsulation techniques developed as part of this project to self-healing formulations.

  10. Electrically reconfigurable logic array

    NASA Technical Reports Server (NTRS)

    Agarwal, R. K.

    1982-01-01

    To compose the complicated systems using algorithmically specialized logic circuits or processors, one solution is to perform relational computations such as union, division and intersection directly on hardware. These relations can be pipelined efficiently on a network of processors having an array configuration. These processors can be designed and implemented with a few simple cells. In order to determine the state-of-the-art in Electrically Reconfigurable Logic Array (ERLA), a survey of the available programmable logic array (PLA) and the logic circuit elements used in such arrays was conducted. Based on this survey some recommendations are made for ERLA devices.

  11. Characterization of microcapsulated β-carotene formed by complex coacervation using casein and gum tragacanth.

    PubMed

    Jain, Ashay; Thakur, Deepika; Ghoshal, Gargi; Katare, O P; Shivhare, U S

    2016-06-01

    Complex coacervation in casein/gum tragacanth (CAS/GT) mixtures was studied as a function of pH, initial protein to polysaccharide mixing ratio (Pr:Ps), total biopolymer concentration, core material load and ionic strength. This study is aimed at understanding how these parameters influence the coacervation kinetics, the coacervate yield, and entrapment efficiency. At a Pr:Ps=2:1, an optimum pH of complex coacervation was found 4.35, at which the intensity of electrostatic interaction was maximum. At these conditions, the phase separation occurred the fastest and the final coacervate yield and entrapment efficiency were the largest. Moreover, the developed β-carotene loaded microcapsules formulation was found to have particle size 159.71±2.16μm, coacervates yield 82.51±0.412%, entrapment efficiency 79.36±0.541%. Varying the Pr:Ps shifted the value of optimum pH. Electrostatic interaction and formation of coacervates was confirmed by Fourier Transform Infra Red (FTIR) spectra. Size and surface properties of coacervates were studied using Scanning Electron Microscopy (SEM). Entrapment of core material within the coacervates was confirmed by Confocal Laser Scanning Microscope (CLSM). The resultant formulation was evaluated for release study and antioxidant activity. Stability of encapsulated β-carotene was evaluated under three levels of temperature (5, 25 and 40°C) for 3 months. Encapsulation strongly increased the stability of micronutrients. Our results advocate potential of microcapsules as a novel carrier for the safeguard and sustained release of micronutrient. PMID:26851204

  12. RF MEMS Based Reconfigurable Antennas

    NASA Technical Reports Server (NTRS)

    Simons, Rainee N.

    2004-01-01

    The presentation will first of all address the advantages of RF MEMS circuit in antenna applications and also the need for electronically reconfigurable antennas. Next, discuss some of the recent examples of RF MEMS based reconfigurable microstrip antennas. Finally, conclude the talk with a summary of MEMS antenna performance.

  13. A Course on Reconfigurable Processors

    ERIC Educational Resources Information Center

    Shoufan, Abdulhadi; Huss, Sorin A.

    2010-01-01

    Reconfigurable computing is an established field in computer science. Teaching this field to computer science students demands special attention due to limited student experience in electronics and digital system design. This article presents a compact course on reconfigurable processors, which was offered at the Technische Universitat Darmstadt,…

  14. Chain reconfiguration in active noise

    NASA Astrophysics Data System (ADS)

    Samanta, Nairhita; Chakrabarti, Rajarshi

    2016-05-01

    In a typical single molecule experiment, the dynamics of an unfolded protein is studied by determining the reconfiguration time using long-range Förster resonance energy transfer, where the reconfiguration time is the characteristic decay time of the position correlation between two residues of the protein. In this paper we theoretically calculate the reconfiguration time for a single flexible polymer in the presence of active noise. The study suggests that though the mean square displacement grows faster, the chain reconfiguration is always slower in the presence of long-lived active noise with exponential temporal correlation. Similar behavior is observed for a worm-like semi-flexible chain and a Zimm chain. However it is primarily the characteristic correlation time of the active noise and not the strength that controls the increase in the reconfiguration time. In brief, such active noise makes the polymer move faster but the correlation loss between the monomers becomes slow.

  15. Tuning the mechanical properties of silica microcapsules.

    PubMed

    Zhang, Lijuan; D'Acunzi, Maria; Kappl, Michael; Imhof, Arnout; van Blaaderen, Alfons; Butt, Hans-Jürgen; Graf, Robert; Vollmer, Doris

    2010-12-21

    Heat treatment is a standard method to increase the hardness of silica in various applications. Here, we tested the effect of high temperature annealing on the mechanical properties of silica microcapsules by force spectroscopy under point loads applied to the particle shell. The Young's modulus of the shells moderately increases after annealing at temperatures above 500 °C. Temperatures over 850 °C result in a much stronger increase and the Young's modulus is close to that of fused silica after annealing at 1100 °C. NMR analysis revealed that in untreated microcapsules synthesized by seeded growth using the Stöber method only 55% of the silicon atoms form siloxane bonds with four neighbors, whereas the remaining ones only form three or less siloxane bonds each and, thus, a large number of ethoxy and silanol groups still exist. During annealing at 500 °C, these are successively transformed into siloxane bonds through condensation reactions. This process correlates with only a moderate increase in Young's modulus. The strong increase at temperatures above 850 °C was associated with a densification which was associated by a decrease in capsule size and shell thickness while the shells remained homogenous and of spherical shape. The main strengthening of the shells is thus mainly due to compaction by sintering at length scales significantly larger than that of local siloxane bonds. PMID:20963236

  16. Synthesis of microcapsules containing different extractant agents.

    PubMed

    Alcázar, Ángela; Carmona, Manuel; Borreguero, Ana M; de Lucas, Antonio; Rodríguez, Juan F

    2015-01-01

    Mercury is one of the most toxic pollutants, with high capacity of accumulation in living organism, causing important human health problems. Therefore, the mercury removal from water is an important research goal. In a previous work, an extractant agent [di(2-ethylhexyl)phosphoric acid] was microencapsulated in poly(styrene-co-divinylbenzene) by means of suspension polymerisation using toluene as diluent. In this study, this recipe has been modified changing the toluene by heptane and extended to four additional extractants (trioctylamine, trioctylmethylammonium chloride [TOMAC], tributyl phosphate and trioctylphosphine oxide). The polluting potential of the waste liquid from the process was measured by total organic carbon and chemical oxygen demand analyses. The morphology, particle size and distribution were studied by scanning electron microscopy and low angle laser light scattering. The amount of extractant agent into the microcapsules and the microencapsulation efficiency were determined by thermogravimetric analysis and the mercury removal capacity by equilibrium studies. Microcapsules containing TOMAC demonstrated to be the best material for the mercury removal and retention. PMID:26299426

  17. Physical characteristics of cinnamon oil microcapsule

    NASA Astrophysics Data System (ADS)

    Hermanto, R. F.; Khasanah, L. U.; Kawiji; Atmaka, W.; Manuhara, G. J.; Utami, R.

    2016-02-01

    Cinnamon (Cinnamomum burmanii) oil products can be obtained from the bark by steam distillation. Essential oils are susceptible to high temperatures, oxidation, UV light, and humidity. Microencapsulation may change essential oils into powder, protect the sensitive core material and reduce the amount of flavor which lost during storage. In the microencapsulation, one of the important factors is the type of coating agent. The objective of this work was to characterize the cinnamon oil microcapsule. Ratio variations of coating agent maltodextrin and gum arabic were (1:0); (0:1); (1:1); (2:3). Physical characteristics such as water content, solubility, bulk density, surface oil, and microencapsulation efficiency of samples were investigated. Results showed that the ratio variations of the coating agent significantly affected the water content, bulk density, surface oil and microencapsulation efficiency but significantly affected the water solubility. Characteristics of selected microcapsule were 6.13% water content; 96.33% solubility; 0.46 g/cm3 bulk density; 2.68% surface oil; 70.68% microencapsulation efficiency and microstructures were rather good.

  18. Reconfigurable multiport EPON repeater

    NASA Astrophysics Data System (ADS)

    Oishi, Masayuki; Inohara, Ryo; Agata, Akira; Horiuchi, Yukio

    2009-11-01

    An extended reach EPON repeater is one of the solutions to effectively expand FTTH service areas. In this paper, we propose a reconfigurable multi-port EPON repeater for effective accommodation of multiple ODNs with a single OLT line card. The proposed repeater, which has multi-ports in both OLT and ODN sides, consists of TRs, BTRs with the CDR function and a reconfigurable electrical matrix switch, can accommodate multiple ODNs to a single OLT line card by controlling the connection of the matrix switch. Although conventional EPON repeaters require full OLT line cards to accommodate subscribers from the initial installation stage, the proposed repeater can dramatically reduce the number of required line cards especially when the number of subscribers is less than a half of the maximum registerable users per OLT. Numerical calculation results show that the extended reach EPON system with the proposed EPON repeater can save 17.5% of the initial installation cost compared with a conventional repeater, and can be less expensive than conventional systems up to the maximum subscribers especially when the percentage of ODNs in lightly-populated areas is higher.

  19. The improvement of phycocyanin stability extracted from Spirulina sp using extrusion encapsulation technique

    NASA Astrophysics Data System (ADS)

    Suzery, Meiny; Hadiyanto, Sutanto, Heri; Soetrisnanto, Danny; Majid, Dian; Setyawan, Deny; Azizah, Nur

    2015-12-01

    The stability of phycocyanin extracted from microalgae Spirulina has been evaluated and it showed that the stability of this antioxidant was affected by temperature and pH changes. The encapsulation technique was of the alternatives to overcome this stability changes. The objective of this paper was to investigate the effects of coating materials (alginate and chitosan) during encapsulation by using extrusion technique. The experiments were conducted with variation of alginate as coating materials. The size of each microcapsules was evaluated by using SEM/XRD for its size and homogeneity.

  20. Adhesion of perfume-filled microcapsules to model fabric surfaces.

    PubMed

    He, Yanping; Bowen, James; Andrews, James W; Liu, Min; Smets, Johan; Zhang, Zhibing

    2014-01-01

    The retention and adhesion of melamine formaldehyde (MF) microcapsules on a model fabric surface in aqueous solution were investigated using a customised flow chamber technique and atomic force microscopy (AFM). A cellulose film was employed as a model fabric surface. Modification of the cellulose with chitosan was found to increase the retention and adhesion of microcapsules on the model fabric surface. The AFM force-displacement data reveal that bridging forces resulting from the extension of cellulose chains dominate the adhesion between the microcapsule and the unmodified cellulose film, whereas electrostatic attraction helps the microcapsules adhere to the chitosan-modified cellulose film. The correlation between results obtained using these two complementary techniques suggests that the flow chamber device can be potentially used for rapid screening of the effect of chemical modification on the adhesion of microparticles to surfaces, reducing the time required to achieve an optimal formulation. PMID:24697187

  1. pH Sensitive Microcapsules for Delivery of Corrosion Inhibitors

    NASA Technical Reports Server (NTRS)

    Li, Wenyan; Calle, Luz M.

    2006-01-01

    A considerable number of corrosion problems can be solved by coatings. However, even the best protective coatings can fail by allowing the slow diffusion of oxygen and moisture to the metal surface. Corrosion accelerates when a coating delaminates. Often, the problems start when microscopic nicks or pits on the surface develop during manufacturing or through wear and tear. This problem can be solved by the incorporation of a self-healing function into the coating. Several new concepts are currently under development to incorporate this function into a coating. Conductive polymers, nanoparticles, and microcapsules are used to release corrosion-inhibiting ions at a defect site. The objective of this investigation is to develop a smart coating for the early detection and inhibition of corrosion. The dual function of this new smart coating system is performed by pH-triggered release microcapsules. The microcapsules can be used to deliver healing agents to terminate the corrosion process at its early stage or as corrosion indicators by releasing dyes at the localized corrosion sites. The dyes can be color dyes or fluorescent dyes, with or without pH sensitivity. Microcapsules were formed through the interfacial polymerization process. The average size of the microcapsules can be adjusted from 1 to 100 micron by adjusting the emulsion formula and the microcapsule forming conditions. A typical microcapsule size is around 10 microns with a narrow size distribution. The pH sensitivity of the microcapsule can also be controlled by adjusting the emulsion formula and the polymerization reaction time. Both corrosion indicator (pH indicator) and corrosion inhibitor containing microcapsules were formed and incorporated into paint systems. Test panels of selected steels and aluminum alloys were painted using these paints. Testing of compatibility between the microcapsule system and different paint systems are in progress. Initial experiments with the microcapsule containing paint

  2. Injectable PLGA/Hydroxyapatite/Chitosan Microcapsules Produced by Supercritical Emulsion Extraction Technology: An In Vitro Study on Teriparatide/Gentamicin Controlled Release.

    PubMed

    Della Porta, Giovanna; Campardelli, Roberta; Cricchio, Vincenzo; Oliva, Francesco; Maffulli, Nicola; Reverchon, Ernesto

    2016-07-01

    Supercritical emulsion extraction (SEE) is proposed as a green and effective strategy for the fabrication of chitosan-covered poly-lactic-co-glycolic acid (chi-PLGA) injectable microcapsules for the controlled release of teriparatide (THA) and teriparatide/gentamicin sulfate (THA/Gen). These formulations can be used for locally bone pathologies treatment or in complex fracture healing of aged patients. Several oil-water (o-w) and water-oil-water (w-o-w) emulsions were processed by SEE to produce multifunctional microcapsules containing hydroxyapatite (HA) within a poly-lactic-co-glycolic acid (PLGA) matrix (up to 24 mg/g) and with both THA (0.45 mg/g) and Gen (up to 9 mg/g). Chitosan coating was also successfully added, as external layer (0.4 μm). SEE-fabricated microcapsules showed good encapsulation efficiency (up to 90%) for all the drugs tested and a mean size ranging between 1.4 (±0.4) μm and 2.2 (±0.5) μm. Different drug amounts loaded and microcapsules compositions assured a controlled drug release over a wide range of times and concentrations, as in vitro monitored in PBS medium at 37°C for 15/20 days. HA embedded into the biopolymer structure delayed the THA release profile; chitosan coating strongly reduced the initial drug "burst" release. In addition, the coencapsulation of both THA and Gen, which have very different water solubility, accelerated the release profile of the less water-soluble drug. No drugs degradation was also monitored after the SEE manufacturing. Apparent drug diffusivities (D) were calculated by fitting of the release profiles. In the case of Gen, D ranged between 2.9 × 10(-8) and 1.6 × 10(-9) cm(2)s(-1) if the drug was entrapped in simple PLGA or in the chitosan-coated microcapsules, respectively. In the case of THA, the calculated values ranged between 8.1 × 10(-9) and 7.4 × 10(-10) cm(2)s(-1) when the drug was entrapped in PLGA/HA microcapsules or in the chitosan-coated ones, respectively. These mass transfer values

  3. Raman Spectroscopy of Poly-Urea Formaldehyde Microcapsules

    NASA Astrophysics Data System (ADS)

    Espino, Omar; Chipara, Dorina; Chipara, Mircea; Martinez, Melissa

    2015-03-01

    The objective of this research project was to add self-healing capabilities to polymeric nanocomposites. We used the ``classical'' method to obtain self-healing polymers with the addition of TiO2 nanoparticles in the self-healing system. Self-healing polymers are obtained by dispersion of first generation Grubbs catalysts and microcapsules filled with monomers (typically DCPD). These kind of ``smart materials'' are able to survive to high mechanical stress via the ignition of the so called ``autonomous self-healing mechanism'' which is actually a ring opening methatesis polymerization (ROMP) reaction triggered by mechanical stresses in excess over a threshold limit through the rupture of microcapsules and the release of the monomeric content. As a preliminary step for adding self-healing capabilities in nanocomposites, the synthesis of microcapsules filled with dicyclopentadiene (DCPD) is vital for the addition of self-healing capabilities to polymeric matrices. We synthesized polyurea-formaldehyde (PUF) microcapsules filled with monomer (DCPD) using the in-situ polymerization. The synthesis was monitored by Raman spectroscopy, optical microscopy, and pH measurements that has been extensively used as a non-invasive techniques in the characterization of polymers and monitoring of organic reactions. The goal of this research was to assess the formation of the microcapsules during synthesis and the presence of the DCPD in the microcapsules. Samples were taken during the synthesis every 30 minutes and analyzed by Raman spectroscopy, and optical microscopy keeping a control over the pH of the solution.

  4. Preparation and In Vitro, In Vivo Evaluation of Clarithromycin Microcapsules

    PubMed Central

    Hu, Liandong; Liu, Wei; Li, Li; Zhao, Jiqiang; Yang, Xun

    2010-01-01

    PURPOSE: To develop and validate a method to prepare clarithromycin (CLM) microcapsules to mask the bitter taste and provide effective treatment, and evaluate the quality of microcapsules in detail, especially the in vitro and in vivo pharmacokinetics behavior. METHODS: CLM microcapsules were prepared using ethyl cellulose as matrix material by an emulsion solvent diffusion method. The physicochemical property, in vitro release study, sensory test and stability test were evaluated. Self-made CLM dry suspension or conventional tablets containing 250 mg of CLM were orally administered with 250 mL of water. The plasma concentration was determined and the pharmacokinetic parameters were calculated by non-compartmental methods. RESULTS: Stable microcapsules could be prepared using ethyl cellulose as matrix material. The quality evaluation of prepared microcapsules was qualified, and the pharmacokinetic parameters of dry suspensions and conventional tablets were as following. Cmax were 1.32±0.62 and 1.40±0.58 μg.ml-1; Tmax were 3.51±0.54 and 2.01±0.42 h; AUC were 7.65±2.54 and 7.12±2.10 μg.h.ml-1. CONCLUSION: The preparation method is easy and applicable. The self-made CLM dry suspension containing microcapsules sufficiently alleviate the bitterness of commercial CLM dry suspension, but not decrease the bioavailability and have better effect for delaying drug release in healthy volunteers PMID:24825996

  5. Reconfigurable fuzzy cell

    NASA Technical Reports Server (NTRS)

    Salazar, George A. (Inventor)

    1993-01-01

    This invention relates to a reconfigurable fuzzy cell comprising a digital control programmable gain operation amplifier, an analog-to-digital converter, an electrically erasable PROM, and 8-bit counter and comparator, and supporting logic configured to achieve in real-time fuzzy systems high throughput, grade-of-membership or membership-value conversion of multi-input sensor data. The invention provides a flexible multiplexing-capable configuration, implemented entirely in hardware, for effectuating S-, Z-, and PI-membership functions or combinations thereof, based upon fuzzy logic level-set theory. A membership value table storing 'knowledge data' for each of S-, Z-, and PI-functions is contained within a nonvolatile memory for storing bits of membership and parametric information in a plurality of address spaces. Based upon parametric and control signals, analog sensor data is digitized and converted into grade-of-membership data. In situ learn and recognition modes of operation are also provided.

  6. Reconfigurable mosaic annular arrays.

    PubMed

    Thomenius, Kai E; Wodnicki, Robert; Cogan, Scott D; Fisher, Rayette A; Burdick, Bill; Smith, L Scott; Khuri-Yakub, Pierre; Lin, Der-Song; Zhuang, Xuefeng; Bonitz, Barry; Davies, Todd; Thomas, Glen; Woychik, Charles

    2014-07-01

    Mosaic annular arrays (MAA) based on reconfigurable array (RA) transducer electronics assemblies are presented as a potential solution for future highly integrated ultrasonic transducer subsystems. Advantages of MAAs include excellent beam quality and depth of field resulting from superior elevational focus compared with 1-D electronically scanned arrays, as well as potentially reduced cost, size, and power consumption resulting from the use of a limited number of beamforming channels for processing a large number of subelements. Specific design tradeoffs for these highly integrated arrays are discussed in terms of array specifications for center frequency, element pitch, and electronic switch-on resistance. Large-area RAs essentially function as RC delay lines. Efficient architectures which take into account RC delay effects are presented. Architectures for integration of the transducer and electronics layers of large-area array implementations are reviewed. PMID:24960699

  7. Layer-by-layer self-assembly of micro-capsules for the magnetic activation of semi-permeable nano-shells

    NASA Astrophysics Data System (ADS)

    Prouty, Malcolm D.

    2007-12-01

    Layer-by-layer (LbL) self-assembly has demonstrated broad perspectives for encapsulating, and the controllable delivery, of drugs. The nano-scale polymer layers have the capability of material protection. Magnetic nanoparticles have great potential to be applied with LbL technology to achieve both "focusing" of the encapsulated drugs to a specific location followed by "switching" them on to release the encapsulated drugs. In this work, Phor21-betaCG(ala), dextran, and dexamethasone were used as model drugs. Encapsulation of these drugs with layer-by-layer self-assembly formed biolnano robotic capsules for controlled delivery and drug release. Silica nanoparticles coated with polyelectrolyte layers of sodium carboxymethyl cellulose (CMC) or gelatin B, along with an oppositely charged peptide drug (Phor2l-betaCG(ala)), were prepared using LbL self-assembly and confirmed using QCM and zeta potential measurements. The peptide drug was assembled as a component of the multilayer walls. The release kinetics of the embedded peptide were determined. Up to 18% of the embedded Phor21-betaCG(ala) was released from the CMC multilayers over a period of 28 hours. The release was based on physiological conditions, and an external control mechanism using magnetic nanoparticles needed to be developed. Magnetic permeability control experiments were setup by applying LbL self-assembly on MnCO3 micro-cores to fabricate polyelectrolyte microcapsules embedded with superparamagnetic gold coated cobalt (Co Au) nanoparticles. An alternating magnetic field was applied to the microcapsules to check for changes in permeability. Permeability experiments were achieved by adding fluorescein isothiocyanate (FITC) labeled dextran to the microcapsule solution. Before an alternating magnetic field was applied, the capsules remained impermeable to the FITC-dextran; however, after an alternating magnetic field was applied for 30 minutes, approximately 99% of the capsules were filled with FITC

  8. Characterization of Encapsulated Corrosion Inhibitors for Environmentally Friendly Smart Coatings

    NASA Technical Reports Server (NTRS)

    Pearman, Benjamin Pieter; Li, Wenyan; Buhrow, Jerry; Zhang, Xuejun; Surma, Jan; Fitzpatrick, Lilly; Montgomery, Eliza; Calle, Luz Marina

    2014-01-01

    Research efforts are under way to replace current corrosion inhibitors with more environmentally friendly alternatives. However, problems with corrosion inhibition efficiency, coating compatibility and solubility have hindered the use of many of these materials as simple pigment additives.This paper will present technical details on how the Corrosion Technology Lab at NASAs Kennedy Space Center (KSC) has addressed these issues by encapsulating environmentally friendly inhibitors into organic and inorganic microparticles and microcapsules. The synthetic process for polymer particles was characterized and post-synthesis analysis was performed to determine the interactions between the inhibitors and the encapsulation material. The pH-controlled release of inhibitors from various particle formulations in aqueous base was monitored and compared to both electrochemical and salt immersion accelerated corrosion experiment. Furthermore, synergistic corrosion inhibition effects observed during the corrosion testing of several inhibitor combinations will be presented.

  9. Deterioration of polyamino acid-coated alginate microcapsules in vivo.

    PubMed

    van Raamsdonk, J M; Cornelius, R M; Brash, J L; Chang, P L

    2002-01-01

    The implantation of immuno-isolated recombinant cell lines secreting a therapeutic protein in alginate microcapsules presents an alternative approach to gene therapy. Its clinical efficacy has recently been demonstrated in treating several genetic diseases in murine models. However, its application to humans will depend on the long-term structural stability of the microcapsules. Based on previous implantations in canines, it appears that survival of alginate-poly-L-lysine-alginate microcapsules in such large animals is short-lived. This article reports on the biological factors that may have contributed to the degradation of these microcapsules after implantation in dogs. Alginate microcapsules coated with poly-L-lysine or poly-L-arginine were implanted in subcutaneous or intraperitoneal sites. The retrieved microcapsules showed a loss of mechanical stability, as measured by resistance to osmotic stress. The polyamino acid coats were rendered fragile and easily lost, particularly when poly-L-lysine was used for coating and the intraperitoneal site was used for implantation. Various plasma proteins were associated with the retrieved microcapsules and identified with western blotting to include Factor XI, Factor XII, prekallikrein, HMWK, fibrinogen, plasminogen, ATIII, transferrin, alpha-1-antitrypsin, fibronectin, IgG, alpha-2-macroglobulin, vitronectin, prothrombin, apolipoprotein A1, and particularly albumin, a major Ca-transporting plasma protein. Complement proteins (C3, Factor B, Factor H, Factor I) and C3 activation fragments were detected. Release of the amino acids from the microcapsule polyamino acid coats was observed after incubation with plasma. indicating the occurrence of proteolytic degradation. Hence, the loss of long-term stability of the polyamino acid-coated alginate microcapsules is associated with activation of the complement system, degradation of the polyamino acid coating, and destabilization of the alginate core matrix, probably through loss

  10. Encapsulated environment.

    PubMed

    McLellan, Tom M; Daanen, Hein A M; Cheung, Stephen S

    2013-07-01

    In many occupational settings, clothing must be worn to protect individuals from hazards in their work environment. However, personal protective clothing (PPC) restricts heat exchange with the environment due to high thermal resistance and low water vapor permeability. As a consequence, individuals who wear PPC often work in uncompensable heat stress conditions where body heat storage continues to rise and the risk of heat injury is greatly enhanced. Tolerance time while wearing PPC is influenced by three factors: (i) initial core temperature (Tc), affected by heat acclimation, precooling, hydration, aerobic fitness, circadian rhythm, and menstrual cycle (ii) Tc tolerated at exhaustion, influenced by state of encapsulation, hydration, and aerobic fitness; and (iii) the rate of increase in Tc from beginning to end of the heat-stress exposure, which is dependent on the clothing characteristics, thermal environment, work rate, and individual factors like body composition and economy of movement. Methods to reduce heat strain in PPC include increasing clothing permeability for air, adjusting pacing strategy, including work/rest schedules, physical training, and cooling interventions, although the additional weight and bulk of some personal cooling systems offset their intended advantage. Individuals with low body fatness who perform regular aerobic exercise have tolerance times in PPC that exceed those of their sedentary counterparts by as much as 100% due to lower resting Tc, the higher Tc tolerated at exhaustion and a slower increase in Tc during exercise. However, questions remain about the importance of activity levels, exercise intensity, cold water ingestion, and plasma volume expansion for thermotolerance. PMID:23897690

  11. Lunar Applications in Reconfigurable Computing

    NASA Technical Reports Server (NTRS)

    Somervill, Kevin

    2008-01-01

    NASA s Constellation Program is developing a lunar surface outpost in which reconfigurable computing will play a significant role. Reconfigurable systems provide a number of benefits over conventional software-based implementations including performance and power efficiency, while the use of standardized reconfigurable hardware provides opportunities to reduce logistical overhead. The current vision for the lunar surface architecture includes habitation, mobility, and communications systems, each of which greatly benefit from reconfigurable hardware in applications including video processing, natural feature recognition, data formatting, IP offload processing, and embedded control systems. In deploying reprogrammable hardware, considerations similar to those of software systems must be managed. There needs to be a mechanism for discovery enabling applications to locate and utilize the available resources. Also, application interfaces are needed to provide for both configuring the resources as well as transferring data between the application and the reconfigurable hardware. Each of these topics are explored in the context of deploying reconfigurable resources as an integral aspect of the lunar exploration architecture.

  12. Encapsulation of Volatile Compounds in Silk Microparticles

    PubMed Central

    Elia, Roberto; Guo, Jin; Budijono, Stephanie; Normand, Valery; Benczédi, Daniel; Omenetto, Fiorenzo

    2015-01-01

    Various techniques have been employed to entrap fragrant oils within microcapsules or microparticles in the food, pharmaceutical, and chemical industries for improved stability and delivery. In the present work we describe the use of silk protein microparticles for encapsulating fragrant oils using ambient processing conditions to form an all-natural biocompatible matrix. These microparticles are stabilized via physical crosslinking, requiring no chemical agents, and are prepared with aqueous and ambient processing conditions using polyvinyl alcohol-silk emulsions. The particles were loaded with fragrant oils via direct immersion of the silk particles within an oil bath. The oil-containing microparticles were coated using alternating silk and polyethylene oxide layers to control the release of the oil from the microspheres. Particle morphology and size, oil loading capacity, release rates as well as silk-oil interactions and coating treatments were characterized. Thermal analysis demonstrated that the silk coatings can be tuned to alter both retention and release profiles of the encapsulated fragrance. These oil containing particles demonstrate the ability to adsorb and controllably release oils, suggesting a range of potential applications including cosmetic and fragrance utility. PMID:26568787

  13. Dual drug delivery microcapsules via layer-by-layer self-assembly.

    PubMed

    Manna, Uttam; Patil, Satish

    2009-09-15

    The integration of hydrophobic and hydrophilic drugs in the polymer microcapsule offers the possibility of developing a new drug delivery system that combines the best features of these two distinct classes of material. Recently, we have reported the encapsulation of an uncharged water-insoluble drug in the polymer membrane. The hydrophobic drug is deposited using a layer-by-layer (LbL) technique, which is based on the sequential adsorption of oppositely charged polyelectrolytes onto a charged substrate. In this paper, we report the encapsulation of two different drugs, which are invariably different in structure and in their solubility in water. We have characterized these dual drug vehicular capsules by confocal laser scanning microscopy, atomic force microscopy, visible microscopy, and transmission electron microscopy. The growth of a thin film on a flat substrate by LbL was monitored by UV-vis spectra. The desorption kinetics of two drugs from the thin film was modeled by a second-order rate model. PMID:19735129

  14. Formation of multilayered biopolymer microcapsules and microparticles in a multiphase microfluidic flow.

    PubMed

    Rondeau, Elisabeth; Cooper-White, Justin J

    2012-06-01

    This paper reports the development of a scalable continuous microfluidic-based method for the preparation of multilayered biopolymer microcapsules and microparticles, with a size range of 1 to 100 μm, in a single-layered polydimethylsiloxane-based device. This new approach has been utilised to produce polyethylene oxide (PEO)-based microparticles, layered with subsequent stage wise coatings of polylactide-based block copolymers and polyvinylpyrrolidone. The production process was shown to allow for on-chip encapsulation of protein and vitamin molecules in the biopolymer micro particles, without any further handling after collection from the device. We have studied the release profiles in the case of model molecules of distinctive molecular weights, namely, vitronectin, horse radish peroxidase, and vitamin B(12). We compared the release properties of the microparticles to those from macro-gels of the same materials prepared off-chip. The results indicated that the microparticles have definitively different molecular weight cut-off characteristics, likely due to a denser microstructure within the microparticles compared to the bulk hydrogels. This difference suggests that significant benefits may exist in the use of this method to produce layered biopolymer microparticles in achieving improved controlled release and encapsulation. PMID:22712036

  15. Stability of Trans-Resveratrol Encapsulated in a Protein Matrix Produced Using Spray Drying to UV Light Stress and Simulated Gastro-Intestinal Digestion.

    PubMed

    Koga, Clarissa C; Andrade, Juan E; Ferruzzi, Mario G; Lee, Youngsoo

    2016-02-01

    Trans-resveratrol has demonstrated the potential to provide both therapeutic and preventive activities against chronic diseases such as heart disease and cancer. The incorporation of trans-resveratrol into food products would allow for broader access of this bioactive compound to a larger population. However, this strategy is limited by instability of trans-resveratrol under environmental conditions and within the digestive system leading to isomerization of trans-resveratrol (bioactive form) to cis-resveratrol (bio-inactive form). Studies in the stabilization of trans-resveratrol into protein microparticles are presented. Trans-resveratrol was encapsulated using whey protein concentrate (WPC) or sodium caseinate (SC), with or without anhydrous milk fat (AMF). Binding of resveratrol and aromatic residues in protein was estimated utilizing the Stern-Volmer equation and the number of tryptophan residues. The stability of encapsulated resveratrol was evaluated after exposure to ultraviolet A (UVA) light and 3-stage in vitro digestion. After UVA light exposure, SC-based microcapsules maintained a higher trans:cis resveratrol ratio (0.63, P < 0.05) than WPC-based microcapsules (0.43) and unencapsulated resveratrol (0.49). In addition, encapsulation of resveratrol in both protein microparticles led to an increased digestive stability and bioaccessibility in comparison to unencapsulated resveratrol (47% and 23%, respectively, P < 0.05). SC-based microcapsules provided a higher digestive stability and bioaccessibility (86% and 81%; P < 0.05) compared to WPC-based microcapsules (71% and 68%). The addition of AMF to the microcapsules did not significantly change the in vitro digestion values. In conclusion, SC-based microencapsulation increased the stability of trans-resveratrol to UVA light exposure and simulated digestion conditions. This encapsulation-system-approach can be extended to other labile, bioactive polyphenols. PMID:26677808

  16. A reconfigurable plasma antenna

    SciTech Connect

    Kumar, Rajneesh; Bora, Dhiraj

    2010-03-15

    An experiment aimed at investigating the antenna properties of different plasma structures of a plasma column as a reconfigurable plasma antenna, is reported. A 30 cm long plasma column is excited by surface wave, which acts as a plasma antenna. By changing the operating parameters, e.g., working pressure, drive frequency, input power, radius of glass tube, length of plasma column, and argon gas, single plasma antenna (plasma column) can be transformed to multiple small antenna elements (plasma blobs). It is also reported that number, length, and separation between two antenna elements can be controlled by operating parameters. Moreover, experiments are also carried out to study current profile, potential profile, conductivity profile, phase relations, radiation power patterns, etc. of the antenna elements. The effect on directivity with the number of antenna elements is also studied. Findings of the study indicate that entire structure of antenna elements can be treated as a phased array broadside vertical plasma antenna, which produces more directive radiation pattern than the single plasma antenna as well as physical properties and directivity of such antenna can be controlled by operating parameters. The study reveals the advantages of a plasma antenna over the conventional antenna in the sense that different antennas can be formed by tuning the operating parameters.

  17. Reconfigurable data path processor

    NASA Technical Reports Server (NTRS)

    Donohoe, Gregory (Inventor)

    2005-01-01

    A reconfigurable data path processor comprises a plurality of independent processing elements. Each of the processing elements advantageously comprising an identical architecture. Each processing element comprises a plurality of data processing means for generating a potential output. Each processor is also capable of through-putting an input as a potential output with little or no processing. Each processing element comprises a conditional multiplexer having a first conditional multiplexer input, a second conditional multiplexer input and a conditional multiplexer output. A first potential output value is transmitted to the first conditional multiplexer input, and a second potential output value is transmitted to the second conditional multiplexer output. The conditional multiplexer couples either the first conditional multiplexer input or the second conditional multiplexer input to the conditional multiplexer output, according to an output control command. The output control command is generated by processing a set of arithmetic status-bits through a logical mask. The conditional multiplexer output is coupled to a first processing element output. A first set of arithmetic bits are generated according to the processing of the first processable value. A second set of arithmetic bits may be generated from a second processing operation. The selection of the arithmetic status-bits is performed by an arithmetic-status bit multiplexer selects the desired set of arithmetic status bits from among the first and second set of arithmetic status bits. The conditional multiplexer evaluates the select arithmetic status bits according to logical mask defining an algorithm for evaluating the arithmetic status bits.

  18. A Reconfigurable Plasmofluidic Lens

    PubMed Central

    Zhao, Chenglong; Liu, Yongmin; Zhao, Yanhui; Fang, Nicholas; Huang, Tony Jun

    2014-01-01

    Plasmonics provides an unparalleled method for manipulating light beyond the diffraction limit, making it a promising technology for the development of ultra-small, ultra-fast, power-efficient optical devices. To date, the majority of plasmonic devices are in the solid state and have limited tunability or configurability. Moreover, individual solid-state plasmonic devices lack the ability to deliver multiple functionalities. Here we utilize laser-induced surface bubbles on a metal film to demonstrate, for the first time, a plasmonic lens in a microfluidic environment. Our “plasmofluidic lens” device is dynamically tunable and reconfigurable. We record divergence, collimation, and focusing of surface plasmon polaritons using this device. The plasmofluidic lens requires no sophisticated nanofabrication and utilizes only a single low-cost diode laser. Our results show that the integration of plasmonics and microfluidics allows for new opportunities in developing complex plasmonic elements with multiple functionalities, high-sensitivity and high-throughput biomedical detection systems, as well as on-chip, all-optical information processing techniques. PMID:23929463

  19. Microcapsule-based techniques for improving the safety of lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Baginska, Marta

    developed to simulate an overheating condition while the cell is cycling. Experimental protocols are developed to assess the performance of the separator in terms of its ability to perform autonomic shutdown and examine tested battery materials using scanning electron microscopy. Another approach to improving battery functionality is via the microencapsulation of battery additives. Currently, additives are added directly into a battery electrolyte, and while they typically perform their function given a sufficient loading, these additives often do so at the expense of battery performance. Microencapsulation allows for a high loading of additives to be incorporated into the cell and their release triggered only when and where they are needed. In this work, microencapsulation techniques are developed to successfully encapsulate 3-hexylthiophene, a stabilizing agent for high-voltage cathodes in Li-ion batteries and conductive polymer precursor, as well as the flame retardant Tris(2-choloroethyl phosphate) (TCP). Microcapsules containing 3-hexylthiophene are coated onto model battery electrodes and immersed in electrolyte. The microcapsule shell wall insulates the 3-hexylthiophene until the microcapsules are mechanically crushed and electropolymerization of the released core to form poly(3-ht) occurs under cyclic voltammetry. In addition, TCP was encapsulated using in situ polymerization. TCP-containing microcapsules are stable in electrolyte at room temperature, but are thermally triggered to release their payload at elevated temperatures. Experimental protocols are developed to study the in situ triggering and release of microencapsulated additives.

  20. Printing of polymer microcapsules for enzyme immobilization on paper substrate.

    PubMed

    Savolainen, Anne; Zhang, Yufen; Rochefort, Dominic; Holopainen, Ulla; Erho, Tomi; Virtanen, Jouko; Smolander, Maria

    2011-06-13

    Poly(ethyleneimine) (PEI) microcapsules containing laccase from Trametes hirsuta (ThL) and Trametes versicolor (TvL) were printed onto paper substrate by three different methods: screen printing, rod coating, and flexo printing. Microcapsules were fabricated via interfacial polycondensation of PEI with the cross-linker sebacoyl chloride, incorporated into an ink, and printed or coated on the paper substrate. The same ink components were used for three printing methods, and it was found that laccase microcapsules were compatible with the ink. Enzymatic activity of microencapsulated TvL was maintained constant in polymer-based ink for at least eight weeks. Thick layers with high enzymatic activity were obtained when laccase-containing microcapsules were screen printed on paper substrate. Flexo printed bioactive paper showed very low activity, since by using this printing method the paper surface was not fully covered by enzyme microcapsules. Finally, screen printing provided a bioactive paper with high water-resistance and the highest enzyme lifetime. PMID:21568314

  1. Smart responsive microcapsules capable of recognizing heavy metal ions.

    PubMed

    Pi, Shuo-Wei; Ju, Xiao-Jie; Wu, Han-Guang; Xie, Rui; Chu, Liang-Yin

    2010-09-15

    Smart responsive microcapsules capable of recognizing heavy metal ions are successfully prepared with oil-in-water-in-oil double emulsions as templates for polymerization in this study. The microcapsules are featured with thin poly(N-isopropylacrylamide-co-benzo-18-crown-6-acrylamide) (P(NIPAM-co-BCAm)) membranes, and they can selectively recognize special heavy metal ions such as barium(II) or lead(II) ions very well due to the "host-guest" complexation between the BCAm receptors and barium(II) or lead(II) ions. The stable BCAm/Ba(2+) or BCAm/Pb(2+) complexes in the P(NIPAM-co-BCAm) membrane cause a positive shift of the volume phase transition temperature of the crosslinked P(NIPAM-co-BCAm) hydrogel to a higher temperature, and the repulsion among the charged BCAm/Ba(2+) or BCAm/Pb(2+) complexes and the osmotic pressure within the P(NIPAM-co-BCAm) membranes result in the swelling of microcapsules. Induced by recognizing barium(II) or lead(II) ions, the prepared microcapsules with P(NIPAM-co-BCAm) membranes exhibit isothermal and significant swelling not only in outer and inner diameters but also in the membrane thickness. The proposed microcapsules in this study are highly attractive for developing smart sensors and/or carriers for detection and/or elimination of heavy metal ions. PMID:20656104

  2. Release properties on gelatin-gum arabic microcapsules containing camphor oil with added polystyrene.

    PubMed

    Chang, Chih-Pong; Leung, Ting-Kai; Lin, Shang-Ming; Hsu, Che-Chang

    2006-07-01

    In this study, gelatin blended with arabic gum microcapsules containing camphor oil with added polystyrene were fabricated by a compound coacervation method. The parameters of oil/wall volume ratio, emulsification stirring speed, concentration of cross-linking agent, treated time and oil release properties were investigated. In order to improve the constant release effect of camphor oil, oil-soluble polystyrene (PS) was used as a sustained release agent. The camphor oil release curves were expressed by the exponential equation: psi(t)=C(eq)(1-e(-t/tau)), where psi(t) represent the variant of camphor oil concentration in the operation environment, C(eq) as the equilibrium state, t as the release time and tau as time constant. C(eq) and tau are significant factors pertaining to the camphor oil release properties. The results indicated that, for the microcapsules, the optimal oil/wall volume ratio was 0.75 to achieve the encapsulation efficiency of 99.6 wt.%. The average particle size were 294.7+/-14.2 microm, 167.2+/-11.2 microm, 85.7+/-8.7 microm at the homogenization stirring speed of 500, 1000, and 2000 rpm, respectively. The effect of sustained oil release will increase whereas the stirring speed decreases and the concentration of glutaraldehyde (GA) and treated time increases. Along with the increasing of quantity of polystyrene added, C(eq) decreased and tau increased, indicating that the sustained oil release amount and the release rate depend on the quantity of PS considerably. PMID:16797942

  3. Intracellularly Biodegradable Polyelectrolyte/Silica Composite Microcapsules as Carriers for Small Molecules.

    PubMed

    Gao, Hui; Goriacheva, Olga A; Tarakina, Nadezda V; Sukhorukov, Gleb B

    2016-04-20

    Microcapsules that can be efficiently loaded with small molecules and effectively released at the target area through the degradation of the capsule shells hold great potential for treating diseases. Traditional biodegradable polyelectrolyte (PE) capsules can be degraded by cells and eliminated from the body but fail to encapsulate drugs with small molecular weight. Here, we report a poly-l-arginine hydrochloride (PARG)/dextran sulfate sodium salt (DEXS)/silica (SiO2) composite capsule that can be destructed in cells and of which the in situ formed inorganic SiO2 enables loading of small model molecules, Rhodamine B (Rh-B). The composite capsules were fabricated based on the layer-by-layer (LbL) technique and the hydrolysis of tetraethoxysilane (TEOS). Capsules composed of nondegradable PEs and SiO2, polyllamine hydrochloride (PAH)/poly(sodium 4-styrenesulfonate) (PSS)/silica (the control sample), were prepared and briefly compared with the degradable composite capsules. An intracellular degradation study of both types of composite capsules revealed that PARG/DEXS/silica capsules were degraded into fragments and lead to the release of model molecules in a relatively short time (2 h), while the structure of PAH/PSS/silica capsules remained intact even after 3 days incubation with B50 cells. Such results indicated that the polymer components played a significant role in the degradability of the SiO2. Specifically, PAH/PSS scaffolds blocked the degradation of SiO2. For PARG/DEXS/silica capsules, we proposed the effects of both hydrolytic degradation of amorphous silica and enzymatic degradation of PARG/DEXS polymers as a cell degradation mechanism. All the results demonstrated a new type of functional composite microcapsule with low permeability, good biocompatibility, and biodegradability for potential medical applications. PMID:27008032

  4. Module encapsulation technology

    NASA Technical Reports Server (NTRS)

    Willis, P.

    1986-01-01

    The identification and development techniques for low-cost module encapsulation materials were reviewed. Test results were displayed for a variety of materials. The improved prospects for modeling encapsulation systems for life prediction were reported.

  5. Release behaviors of porous poly(butylene succinate)/poly(epsilon-caprolactone) microcapsules containing indomethacin.

    PubMed

    Park, Soo-Jin; Lee, Yun-Mok; Hong, Sung-Kwon

    2006-02-01

    The biodegradable poly(butylene succinate)/poly(epsilon-caprolactone) (PBS/PCL) microcapsules containing indomethacin were prepared by emulsion solvent evaporation method. The morphologies, thermal properties, and release behaviors of PBS/PCL microcapsules were investigated. As a result, the microcapsules exhibited porous and spherical form in the presence of gelatin as a surfactant. From the DSC result, the PBS/PCL microcapsules showed the two exothermic peaks meaning the melting points of PCL and PBS. The results of FT-IR and DSC proved that the PBS and PCL were mixed so that the PBS/PCL microcapsules were composed of two wall-forming materials. And the release rate of indomethacin from the microcapsules was decreased with increasing the PCL content. It was noted that an addition of PCL on the PBS led to the decrease of pore size in the PBS/PCL microcapsules. PMID:16413177

  6. Processes in suspensions of nanocomposite microcapsules exposed to external electric fields

    NASA Astrophysics Data System (ADS)

    Ermakov, A. V.; Lomova, M. V.; Kim, V. P.; Chumakov, A. S.; Gorbachev, I. A.; Gorin, D. A.; Glukhovskoy, E. G.

    2016-04-01

    Microcapsules with and without magnetite nanoparticles incorporated in the polyelectrolyte shell were prepared. The effect of external electric field on the nanocomposite polyelectrolyte microcapsules containing magnetite nanoparticles in the shell was studied in this work as a function of the electric field strength. Effect of electric fields on polyelectrolyte microcapsules and the control over integrity of polyelectrolyte microcapsules with and without inorganic nanoparticles by constant electric field has been investigated. Beads effect, aggregation and deformations of nanocomposite microcapsule shell in response to electric field were observed by confocal laser scanning microscopy (CLSM). Thus, a new approach for effect on the nanocomposite microcapsule, including opening microcapsule shell by an electric field, was demonstrated. These results can be used for creation of new systems for drug delivery systems with controllable release by external electric field.

  7. Polymer microcapsules with a fiber-reinforced nanocomposite shell.

    PubMed

    Sagis, Leonard M C; Ruiter, Riëlle de; Miranda, Francisco J Rossier; Ruiter, Jolet de; Schroën, Karin; Aelst, Adriaan C van; Kieft, Henk; Boom, Remko; Linden, Erik van der

    2008-03-01

    Polymer microcapsules can be used as controlled release systems in drugs or in foods. Using layer-by-layer adsorption of common food proteins and polysaccharides, we produced a new type of microcapsule with tunable strength and permeability. The shell consists of alternating layers of pectin and whey protein fibrils, yielding a fiber-reinforced nanocomposite shell. The strength can be tightly controlled by varying the number of layers or the density and length of the fibrils in the protein layers. The mechanical stability of these microcapsules appears to be superior to that of currently available multilayer capsules. The method involves only standard unit operations and has the potential for scaling up to industrial production volumes. PMID:18237217

  8. Improved quorum sensing capacity by culturing Vibrio harveyi in microcapsules.

    PubMed

    Gao, Meng; Song, Huiyi; Liu, Xiudong; Yu, Weiting; Ma, Xiaojun

    2016-04-01

    Microcapsule entrapped low density cells with culture (ELDCwc), different from free cell culture, conferred stronger stress resistance and improved cell viability of microorganisms. In this paper, the quorum sensing (QS) system of Vibrio harveyi was used to investigate changes when cells were cultured in microcapsules. Cells in ELDCwc group grew into cell aggregates, which facilitated cell-cell communication and led to increased bioluminescence intensity. Moreover, the luxS-AI-2 system, a well-studied QS signal pathway, was detected as both luxS gene and the AI-2 signaling molecule, and the results were analyzed with respect to QS capacity of unit cell. The V. harveyi of ELDCwc also showed higher relative gene expression and stronger quorum sensing capacity when compared with free cells. In conclusion, the confined microcapsule space can promote the cell aggregates formation, reduce cell-cell communication distance and increase local concentration of signal molecule, which are beneficial to bacterial QS. PMID:26364746

  9. Magnetic Compression of Polyelectrolyte Microcapsules for Controlled Release.

    PubMed

    Hu, Yanan; Liu, Chuanyong; Li, Dongzhi; Long, Yue; Song, Kai; Tung, Chen-Ho

    2015-10-20

    In this study, microcapsules with a magnetic particle as the core and polyelectrolyte multilayers as the shell were fabricated. The cavity of the microcapsules was created by etching the SiO2 layer, which was first coated on the magnetic core particle, and the size of the cavity can be adjusted by the thickness of the SiO2 layer. This magnetically responsive microcapsule deforms upon application of a constant magnetic field and results in the release of the core content, and the release velocity could be controlled by the strength of the magnetic field. This release mechanism is proactive and repeatable, combined with its localized and remote controllability; it can be a powerful tool for delivering medical agents on site. PMID:26402037

  10. Steady cone-jet mode in compound-fluidic electro-flow focusing for fabricating multicompartment microcapsules

    NASA Astrophysics Data System (ADS)

    Si, Ting; Yin, Chuansheng; Gao, Peng; Li, Guangbin; Ding, Hang; He, Xiaoming; Xie, Bin; Xu, Ronald X.

    2016-01-01

    A compound-fluidic electro-flow focusing (CEFF) process is proposed to produce multicompartment microcapsules. The central device mainly consists of a needle assembly of two parallel inner needles and one outer needle mounted in a gas chamber with their tips facing a small orifice at the bottom of the chamber. As the outer and the inner fluids flow through the needle assembly, a high-speed gas stream elongates the liquid menisci in the vicinity of the orifice entrance. An electric field is further integrated into capillary flow focusing to promote the formation of steady cone-jet mode in a wide range of operation parameters. The multiphase liquid jet is broken up into droplets due to perturbation propagation along the jet surface. To estimate the diameter of the multiphase liquid jet as a function of process parameters, a modified scaling law is derived and experimentally validated. Microcapsules of around 100 μm with an alginate shell and multiple cores at a production rate of 103-105 per second are produced. Technical feasibility of stimulation triggered coalescence and drug release is demonstrated by benchtop experiments. The proposed CEFF process can be potentially used to encapsulate therapeutic agents and biological cargos for controlled micro-reaction and drug delivery.

  11. Using patterned surfaces to sort elastic microcapsules

    NASA Astrophysics Data System (ADS)

    Alexeev, Alexander; Verberg, Rolf; Balazs, Anna C.

    2007-03-01

    For both biological cells and synthetic microcapsules, mechanical stiffness is a key parameter since it can reveal the presence of disease in the former case and the quality of the fabricated product in the latter case. To date, however, assessing the mechanical properties of such micron scale particles in an efficient, cost-effective means remains a critical challenge. By developing a three-dimensional computational model of fluid-filled, elastic spheres rolling on substrates patterned with diagonal stripes, we demonstrate a useful method for separating cells or microcapules by their compliance. In particular, we examine the fluid-driven motion of these capsules over a hard adhesive surface that contains soft stripes or a weakly adhesive surface that contains ``sticky'' stripes. As a result of their inherently different interactions with the heterogeneous substrate, particles with dissimilar stiffness are dispersed to distinct lateral locations on the surface. Since mechanically and chemically patterned surfaces can be readily fabricated through soft lithography and can easily be incorporated into microfluidic devices, our results point to a facile method for carrying out continuous ``on the fly'' separation processes.

  12. Fabrication of Covalently Crosslinked and Amine-Reactive Microcapsules by Reactive Layer-by-Layer Assembly of Azlactone-Containing Polymer Multilayers on Sacrificial Microparticle Templates

    PubMed Central

    Saurer, Eric M.; Flessner, Ryan M.; Buck, Maren E.; Lynn, David M.

    2011-01-01

    We report on the fabrication of covalently crosslinked and amine-reactive hollow microcapsules using ‘reactive’ layer-by-layer assembly to deposit thin polymer films on sacrificial microparticle templates. Our approach is based on the alternating deposition of layers of a synthetic polyamine and a polymer containing reactive azlactone functionality. Multilayered films composed of branched poly(ethylene imine) (BPEI) and poly(2-vinyl-4,4-dimethylazlactone) (PVDMA) were fabricated layer-by-layer on the surfaces of calcium carbonate and glass microparticle templates. After fabrication, these films contained residual azlactone functionality that was accessible for reaction with amine-containing molecules. Dissolution of the calcium carbonate or glass cores using aqueous ethylenediamine tetraacetic acid (EDTA) or hydrofluoric acid (HF), respectively, led to the formation of hollow polymer microcapsules. These microcapsules were robust enough to encapsulate and retain a model macromolecule (FITC-dextran) and were stable for at least 22 hours in high ionic strength environments, in low and high pH solutions, and in several common organic solvents. Significant differences in the behaviors of capsules fabricated on CaCO3 and glass cores were observed and characterized using scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). Whereas capsules fabricated on CaCO3 templates collapsed upon drying, capsules fabricated on glass templates remained rigid and spherical. Characterization using EDS suggested that this latter behavior results, at least in part, from the presence of insoluble metal fluoride salts that are trapped or precipitate within the walls of capsules after etching of the glass cores using HF. Our results demonstrate that the assembly of BPEI/PVDMA films on sacrificial templates can be used to fabricate reactive microcapsules of potential use in a wide range of fields, including catalysis, drug and gene delivery, imaging, and

  13. Robot Would Reconfigure Modular Equipment

    NASA Technical Reports Server (NTRS)

    Purves, Lloyd R.

    1993-01-01

    Special-purpose sets of equipment, packaged in identical modules with identical interconnecting mechanisms, attached to or detached from each other by specially designed robot, according to proposal. Two-arm walking robot connects and disconnects modules, operating either autonomously or under remote supervision. Robot walks along row of connected modules by grasping successive attachment subassemblies in hand-over-hand motion. Intended application for facility or station in outer space; robot reconfiguration scheme makes it unnecessary for astronauts to venture outside spacecraft or space station. Concept proves useful on Earth in assembly, disassembly, or reconfiguration of equipment in such hostile environments as underwater, near active volcanoes, or in industrial process streams.

  14. Antenna reconfiguration verification and validation

    NASA Technical Reports Server (NTRS)

    Becker, Robert C. (Inventor); Meyers, David W. (Inventor); Muldoon, Kelly P. (Inventor); Carlson, Douglas R. (Inventor); Drexler, Jerome P. (Inventor)

    2009-01-01

    A method of testing the electrical functionality of an optically controlled switch in a reconfigurable antenna is provided. The method includes configuring one or more conductive paths between one or more feed points and one or more test point with switches in the reconfigurable antenna. Applying one or more test signals to the one or more feed points. Monitoring the one or more test points in response to the one or more test signals and determining the functionality of the switch based upon the monitoring of the one or more test points.

  15. Self-assembled gold coating enhances X-ray imaging of alginate microcapsules

    NASA Astrophysics Data System (ADS)

    Qie, Fengxiang; Astolfo, Alberto; Wickramaratna, Malsha; Behe, Martin; Evans, Margaret D. M.; Hughes, Timothy C.; Hao, Xiaojuan; Tan, Tianwei

    2015-01-01

    Therapeutic biomolecules produced from cells encapsulated within alginate microcapsules (MCs) offer a potential treatment for a number of diseases. However the fate of such MCs once implanted into the body is difficult to establish. Labelling the MCs with medical imaging contrast agents may aid their detection and give researchers the ability to track them over time thus aiding the development of such cellular therapies. Here we report the preparation of MCs with a self-assembled gold nanoparticle (AuNPs) coating which results in distinctive contrast and enables them to be readily identified using a conventional small animal X-ray micro-CT scanner. Cationic Reversible Addition-Fragmentation chain Transfer (RAFT) homopolymer modified AuNPs (PAuNPs) were coated onto the surface of negatively charged alginate MCs resulting in hybrids which possessed low cytotoxicity and high mechanical stability in vitro. As a result of their high localized Au concentration, the hybrid MCs exhibited a distinctive bright circular ring even with a low X-ray dose and rapid scanning in post-mortem imaging experiments facilitating their positive identification and potentially enabling them to be used for in vivo tracking experiments over multiple time-points.Therapeutic biomolecules produced from cells encapsulated within alginate microcapsules (MCs) offer a potential treatment for a number of diseases. However the fate of such MCs once implanted into the body is difficult to establish. Labelling the MCs with medical imaging contrast agents may aid their detection and give researchers the ability to track them over time thus aiding the development of such cellular therapies. Here we report the preparation of MCs with a self-assembled gold nanoparticle (AuNPs) coating which results in distinctive contrast and enables them to be readily identified using a conventional small animal X-ray micro-CT scanner. Cationic Reversible Addition-Fragmentation chain Transfer (RAFT) homopolymer modified Au

  16. Transplantation of Encapsulated Pancreatic Islets as a Treatment for Patients with Type 1 Diabetes Mellitus

    PubMed Central

    Qi, Meirigeng

    2014-01-01

    Encapsulation of pancreatic islets has been proposed and investigated for over three decades to improve islet transplantation outcomes and to eliminate the side effects of immunosuppressive medications. Of the numerous encapsulation systems developed in the past, microencapsulation have been studied most extensively so far. A wide variety of materials has been tested for microencapsulation in various animal models (including nonhuman primates or NHPs) and some materials were shown to induce immunoprotection to islet grafts without the need for chronic immunosuppression. Despite the initial success of microcapsules in NHP models, the combined use of islet transplantation (allograft) and microencapsulation has not yet been successful in clinical trials. This review consists of three sections: introduction to islet transplantation, transplantation of encapsulated pancreatic islets as a treatment for patients with type 1 diabetes mellitus (T1DM), and present challenges and future perspectives. PMID:26556410

  17. Preparation of uniform-sized PLA microcapsules by combining Shirasu porous glass membrane emulsification technique and multiple emulsion-solvent evaporation method.

    PubMed

    Liu, Rong; Ma, Guanghui; Meng, Fan-Tao; Su, Zhi-Guo

    2005-03-01

    Relatively Uniform-sized biodegradable poly(lactide) (PLA) microcapsules were successfully prepared by combining a Shirasu Porous Glass (SPG) membrane emulsification technique and multiple emulsion-solvent evaporation method. An aqueous phase containing lysozyme was used as the internal water phase (w1), and PLA and Arlacel 83 were dissolved in a mixture solvent of dichloromethane (DCM) and toluene which was used as the oil phase (o). These two solutions were emulsified by a homogenizer to form a w1/o primary emulsion. The primary emulsion was permeated through the uniform pores (5.25 microm) of an SPG membrane into the external water phase by the pressure of nitrogen gas to form the uniform w1/o/w2 droplets. Then, the solid polymer microcapsules were obtained by simply evaporating the solvent. It is necessary to avoid the phase separation of primary emulsion during the SPG membrane emulsification. It was found that when the density difference of the internal water phase and oil phase was reduced to nearly zero and Arlacel 83 was used as the oil emulsifier, the phase separation was not observed within 24 h. The w1/o/w2 emulsion with uniform diameter was obtained only when Arlaecl 83 concentration was limited below 2.5 wt.% based on oil phase. The drug encapsulation efficiency was found to be related to several factors including PLA molecular weight, additive type and its concentration in the internal water phase, the emulsifier type and concentration in the oil phase, the NaCl concentration and the pH value in the external water phase. Comparing with the stirring method, it was found that the size was more uniform and the drug encapsulation efficiency was much higher when the microcapsules were prepared by SPG membrane emulsification technique and the highest drug encapsulation efficiency of 92.20% was obtained. This is the first study to prepare PLA microcapsules by combining an SPG membrane emulsification technique and multiple emulsion-solvent evaporation method

  18. Bio-insecticide Bacillus thuringiensis spores encapsulated with amaranth derivatized starches: studies on the propagation "in vitro".

    PubMed

    Rodríguez, Ana Priscila García; Martínez, Marcela Gaytán; Barrera-Cortés, Josefina; Ibarra, Jorge E; Bustos, Fernando Martínez

    2015-02-01

    Bacillus thuringiensis (Bt) is one of the bioinsecticides used worldwide due to its specific toxicity against target pests in their larval stage. Despite this advantage, its use is limited because of their short persistence in field when exposed to ultra violet light and changing environmental conditions. In this work, microencapsulation has been evaluated as a promising method to improve Bt activity. The objective of this study was to develop and characterize native and modified amaranth starch granules and evaluate their potential application as wall materials in the microcapsulation of B thuringiensis serovar kurstaki HD-1 (Bt- HD1), produced by spray drying. Native amaranth starch granules were treated by hydrolyzation, high energy milling (HEM) and were chemically modified by phosphorylation and succinylation. The size of the Bt microcapsules varied from 12.99 to 17.14 μm adequate to protect the spores of Bt from ultraviolet radiation. The aw coefficient of the microcapsules produced by the modified starches after drying was low (0.14-1.88), which prevent microbial growth. Microcapsules prepared with phosphorylated amaranth starch presented the highest bacterial count and active material yield. Different concentrations of the encapsulated Bt formulation in phosphorylated amaranth starch showed a high level of insecticidal activity when tested on M. sexta larvae and has great potential to be developed as a bioinsecticide formulation, also, the level of toxicity is much higher than that found in some of the products commercially available. PMID:25168123

  19. 21 CFR 172.230 - Microcapsules for flavoring substances.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Microcapsules for flavoring substances. 172.230 Section 172.230 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD ADDITIVES PERMITTED FOR DIRECT ADDITION TO FOOD FOR HUMAN CONSUMPTION Coatings, Films...

  20. 21 CFR 172.230 - Microcapsules for flavoring substances.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... limitations Succinylated gelatin—Not to exceed 15 percent by combined weight of the microcapsule and flavoring oil. Succinic acid content of the gelatin is 4.5 to 5.5 percent. Arabinogalactan—Complying with § 172... Glutaraldehyde—As cross-linking agent for insolubilizing a coacervate of gum arabic and gelatin. n-Octyl...

  1. 21 CFR 172.230 - Microcapsules for flavoring substances.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... limitations Succinylated gelatin—Not to exceed 15 percent by combined weight of the microcapsule and flavoring oil. Succinic acid content of the gelatin is 4.5 to 5.5 percent. Arabinogalactan—Complying with § 172... Glutaraldehyde—As cross-linking agent for insolubilizing a coacervate of gum arabic and gelatin. n-Octyl...

  2. 21 CFR 172.230 - Microcapsules for flavoring substances.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... limitations Succinylated gelatin—Not to exceed 15 percent by combined weight of the microcapsule and flavoring oil. Succinic acid content of the gelatin is 4.5 to 5.5 percent. Arabinogalactan—Complying with § 172... Glutaraldehyde—As cross-linking agent for insolubilizing a coacervate of gum arabic and gelatin. n-Octyl...

  3. 21 CFR 172.230 - Microcapsules for flavoring substances.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... limitations Succinylated gelatin—Not to exceed 15 percent by combined weight of the microcapsule and flavoring oil. Succinic acid content of the gelatin is 4.5 to 5.5 percent. Arabinogalactan—Complying with § 172... Glutaraldehyde—As cross-linking agent for insolubilizing a coacervate of gum arabic and gelatin. n-Octyl...

  4. Polyelectrolyte Microcapsules: Ion Distributions from a Poisson-Boltzmann Model

    NASA Astrophysics Data System (ADS)

    Tang, Qiyun; Denton, Alan R.; Rozairo, Damith; Croll, Andrew B.

    2014-03-01

    Recent experiments have shown that polystyrene-polyacrylic-acid-polystyrene (PS-PAA-PS) triblock copolymers in a solvent mixture of water and toluene can self-assemble into spherical microcapsules. Suspended in water, the microcapsules have a toluene core surrounded by an elastomer triblock shell. The longer, hydrophilic PAA blocks remain near the outer surface of the shell, becoming charged through dissociation of OH functional groups in water, while the shorter, hydrophobic PS blocks form a networked (glass or gel) structure. Within a mean-field Poisson-Boltzmann theory, we model these polyelectrolyte microcapsules as spherical charged shells, assuming different dielectric constants inside and outside the capsule. By numerically solving the nonlinear Poisson-Boltzmann equation, we calculate the radial distribution of anions and cations and the osmotic pressure within the shell as a function of salt concentration. Our predictions, which can be tested by comparison with experiments, may guide the design of microcapsules for practical applications, such as drug delivery. This work was supported by the National Science Foundation under Grant No. DMR-1106331.

  5. Reconfigurable fault tolerant avionics system

    NASA Astrophysics Data System (ADS)

    Ibrahim, M. M.; Asami, K.; Cho, Mengu

    This paper presents the design of a reconfigurable avionics system based on modern Static Random Access Memory (SRAM)-based Field Programmable Gate Array (FPGA) to be used in future generations of nano satellites. A major concern in satellite systems and especially nano satellites is to build robust systems with low-power consumption profiles. The system is designed to be flexible by providing the capability of reconfiguring itself based on its orbital position. As Single Event Upsets (SEU) do not have the same severity and intensity in all orbital locations, having the maximum at the South Atlantic Anomaly (SAA) and the polar cusps, the system does not have to be fully protected all the time in its orbit. An acceptable level of protection against high-energy cosmic rays and charged particles roaming in space is provided within the majority of the orbit through software fault tolerance. Check pointing and roll back, besides control flow assertions, is used for that level of protection. In the minority part of the orbit where severe SEUs are expected to exist, a reconfiguration for the system FPGA is initiated where the processor systems are triplicated and protection through Triple Modular Redundancy (TMR) with feedback is provided. This technique of reconfiguring the system as per the level of the threat expected from SEU-induced faults helps in reducing the average dynamic power consumption of the system to one-third of its maximum. This technique can be viewed as a smart protection through system reconfiguration. The system is built on the commercial version of the (XC5VLX50) Xilinx Virtex5 FPGA on bulk silicon with 324 IO. Simulations of orbit SEU rates were carried out using the SPENVIS web-based software package.

  6. Preparation of biodegradable liquid core PLLA microcapsules and hollow PLLA microcapsules using microfluidics.

    PubMed

    Lensen, Dennis; van Breukelen, Kevin; Vriezema, Dennis M; van Hest, Jan C M

    2010-05-14

    Biodegradable PLLA capsules with a narrow size distribution were prepared using a microfluidics platform. With this technique, an oil-in-water emulsion was produced in which the polymer, a hydrophobic non-volatile non-solvent and a hydrophobic model drug were dissolved in the organic phase. The polymer precipitated at the droplet interface, yielding a drug deliverable microcapsule of which the release of this model drug was investigated. These capsules with an organic phase in the core were also used to prepare hollow particles by conveniently removing the core phase by lyophilization. Optimal conditions for the preparation of biodegradable capsules were found with respect to the flow rate of the continuous phase and the molecular weight of the PLLA polymer. This approach of preparing biodegradable capsules is of potential interest for the field of drug delivery. PMID:20336699

  7. Dynamic partial FPGA reconfiguration in space applications

    NASA Astrophysics Data System (ADS)

    Graczyk, Rafal; Stolarski, Marcin; Palau, Marie-Catherine; Orleanski, Piotr

    2012-05-01

    Design and implementation of hardware mock-up of high performance system for general avionics testing in reconfigurable FPGAs. Strong emphasis is put on exploiting dynamic partial reconfiguration capability as a method for functionality multiplexing and fault mitigation. Additionally, dynamic reconfiguration can be used for fault injection which makes Single Event Upset in configuration memory simulation possible. LEON3 processors are used to create an avionic systems test-bed, for testing the mock-ups of real system flight software and testing dynamic full and partial reconfiguration. Experiments with different means of reconfiguration are performed to measure reconfiguration times and stability of software. Several solutions for whole system reconfiguration controller have been implemented and tested.

  8. Synthesis of magnetic resonance–, X-ray– and ultrasound-visible alginate microcapsules for immunoisolation and noninvasive imaging of cellular therapeutics

    PubMed Central

    Barnett, Brad P; Arepally, Aravind; Stuber, Matthias; Arifin, Dian R; Kraitchman, Dara L; Bulte, Jeff W M

    2011-01-01

    Cell therapy has the potential to treat or cure a wide variety of diseases. Non-invasive cell tracking techniques are, however, necessary to translate this approach to the clinical setting. This protocol details methods to create microcapsules that are visible by X-ray, ultrasound (US ) or magnetic resonance (MR) for the encapsulation and immunoisolation of cellular therapeutics. Three steps are generally used to encapsulate cellular therapeutics in an alginate matrix: (i) droplets of cell-containing liquid alginate are extruded, using an electrostatic generator, through a needle tip into a solution containing a dissolved divalent cation salt to form a solid gel; (ii) the resulting gelled spheres are coated with polycations as a cross-linker; and (iii) these complexes are then incubated in a second solution of alginate to form a semipermeable membrane composed of an inner and an outer layer of alginate. The microcapsules can be rendered visible during the first step by adding contrast agents to the primary alginate layer. Such contrast agents include superparamagnetic iron oxide for detection by 1H MR imaging (MRI); the radiopaque agents barium or bismuth sulfate for detection by X-ray modalities; or perfluorocarbon emulsions for multimodal detection by 19F MRI, X-ray and US imaging. The entire synthesis can be completed within 2 h. PMID:21799484

  9. Solar cell encapsulation

    NASA Technical Reports Server (NTRS)

    Gupta, Amitava (Inventor); Ingham, John D. (Inventor); Yavrouian, Andre H. (Inventor)

    1983-01-01

    A polymer syrup for encapsulating solar cell assemblies. The syrup includes uncrosslinked poly(n-butyl)acrylate dissolved in n-butyl acrylate monomer. Preparation of the poly(n-butyl)acrylate and preparation of the polymer syrup is disclosed. Methods for applying the polymer syrup to solar cell assemblies as an encapsulating pottant are described. Also included is a method for solar cell construction utilizing the polymer syrup as a dual purpose adhesive and encapsulating material.

  10. Germanium detector vacuum encapsulation

    NASA Technical Reports Server (NTRS)

    Madden, N. W.; Malone, D. F.; Pehl, R. H.; Cork, C. P.; Luke, P. N.; Landis, D. A.; Pollard, M. J.

    1991-01-01

    This paper describes an encapsulation technology that should significantly improve the viability of germanium gamma-ray detectors for a number of important applications. A specialized vacuum chamber has been constructed in which the detector and the encapsulating module are processed in high vacuum. Very high vacuum conductance is achieved within the valveless encapsulating module. The detector module is then sealed without breaking the chamber vacuum. The details of the vacuum chamber, valveless module, processing, and sealing method are presented.