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Sample records for microcapsules encapsulating reconfigurable

  1. Encapsulation and Enhanced Retention of Fragrance in Polymer Microcapsules.

    PubMed

    Lee, Hyomin; Choi, Chang-Hyung; Abbaspourrad, Alireza; Wesner, Chris; Caggioni, Marco; Zhu, Taotao; Weitz, David A

    2016-02-17

    Fragrances are amphiphilic and highly volatile, all of which makes them a challenging cargo to efficiently encapsulate and retain in microcapsules using traditional approaches. We address these limitations by introducing a new strategy that combines bulk and microfluidic emulsification: a stable fragrance-in-water (F/W) emulsion that is primarily prepared from bulk emulsification is incorporated within a polymer microcapsule via microfluidic emulsification. On the basis of the in-depth study of physicochemical properties of the microcapsules on fragrance leakage, we demonstrate that enhanced retention of fragrance can be achieved by using a polar polymeric shell and forming a hydrogel network within the microcapsule. We further extend the utility of these microcapsules by demonstrating the enhanced retention of encapsulated fragrance in powder state.

  2. Enzyme and Chemical Encapsulation in Polymeric Microcapsules,

    DTIC Science & Technology

    1995-01-01

    Polypyrrole microcapsules (prepared via the template method) were used for immobilization of both enzymatic and chemical catalytic systems. Enzymes...immobilized Pd nanoparticles for catalysis of hydrogen peroxide decomposition. Microcapsules loaded with glucose oxidase (GOD) were found to have...from the capsules; no leakage was observed. Subtilisin was used to show that these microcapsules can be used in non-aqueous solvents. The effect of capsule wall thickness on the rate of enzymatic reaction was also explored.

  3. Core-shell hydrogel microcapsules for improved islets encapsulation.

    PubMed

    Ma, Minglin; Chiu, Alan; Sahay, Gaurav; Doloff, Joshua C; Dholakia, Nimit; Thakrar, Raj; Cohen, Joshua; Vegas, Arturo; Chen, Delai; Bratlie, Kaitlin M; Dang, Tram; York, Roger L; Hollister-Lock, Jennifer; Weir, Gordon C; Anderson, Daniel G

    2013-05-01

    Islets microencapsulation holds great promise to treat type 1 diabetes. Currently used alginate microcapsules often have islets protruding outside capsules, leading to inadequate immuno-protection. A novel design of microcapsules with core-shell structures using a two-fluid co-axial electro-jetting is reported. Improved encapsulation and diabetes correction is achieved in a single step by simply confining the islets in the core region of the capsules.

  4. Preparation of inorganic/organic polymer hybrid microcapsules with high encapsulation efficiency by an electrospray technique.

    PubMed

    Yunoki, Ayumi; Tsuchiya, Eiko; Fukui, Yu; Fujii, Akihiro; Maruyama, Tatsuo

    2014-08-13

    Microcapsules composed of calcium phosphate and chitosan were prepared in a single step by electrospraying. An aqueous solution containing calcium chloride and chitosan was electrosprayed into a phosphate solution to form a calcium phosphate shell on the sprayed droplets. The resulting microcapsules were 350 μm in average diameter. Investigation using fluorescently labeled chitosan and XRD measurements revealed that the shells of the microcapsules were composed of calcium phosphate (mainly hydroxyapatite) and chitosan. Instead of chitosan, poly(diallyldimethylammonium chloride) and polyethylene glycol were also available for microcapsule production by electrospraying. Variations in the electrospraying conditions resulted in a variety of microcapsule shapes. Various types of substrates were successfully encapsulated in microcapsules with a high encapsulation efficiency (more than 80%). Finally, we succeeded in the encapsulation of living yeast cells in microcapsules, and observed their growth within these microcapsules.

  5. Laser-triggered release of encapsulated molecules from polylactic-co-glycolic acid microcapsules

    NASA Astrophysics Data System (ADS)

    Ariyasu, Kazumasa; Ishii, Atsuhiro; Umemoto, Taiga; Terakawa, Mitsuhiro

    2016-08-01

    The controlled release of encapsulated molecules from a microcapsule is a promising method of targeted drug delivery. Laser-triggered methods for the release of encapsulated molecules have the advantage of spatial and temporal controllability. In this study, we demonstrated the release of encapsulated molecules from biodegradable polymer-based microcapsules using near-infrared femtosecond laser pulses. The polylactic-co-glycolic acid microcapsules encapsulating fluorescein isothiocyanate-dextran molecules were fabricated using a dual-coaxial nozzle system. Irradiation of femtosecond laser pulses enhanced the release of the molecules from the microcapsules, which was accompanied by a decrease in the residual ratio of the microcapsules. The laser-induced modification of the surface of the shell of the microcapsules indicated the potential for sustained release as well as burst release.

  6. 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.

  7. 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.

  8. Synthesis and characterization of polyurethane-urea microcapsules containing galangal essential oil: statistical analysis of encapsulation.

    PubMed

    Podshivalov, Alexander V; Bronnikov, Sergei; Zuev, Vjacheslav V; Jiamrungraksa, Thichanee; Charuchinda, Sireerat

    2013-01-01

    Galangal essential oil (GEO) is known to possess antimicrobial activity (e.g. against Staphylococcus aureus). A way to increase oil lifetime in plants is encapsulation in polyurethane-urea (PUU) microcapsules. In this study, PUU microcapsules with GEO were synthesized by interfacial polymerization at oil-water interface in oil-water emulsion. A statistical analysis of the microcapsule size was successfully applied for characterization of the encapsulation process. Using the model of reversible aggregation, it was shown that the process of encapsulation takes place in the conditions of thermodynamic control. The polymerization conditions (agitation rate in the range 2000-10 000 rpm/min) are the key factors that affect the mean microcapsule size of primary capsules formed during encapsulation. Two complementary processes were determined the mean capsule size during a transformation of these primary microcapsules: break-up and coalescence of oil droplets in the oil-in-water emulsion. The agitation rate does not influence the coalescence of the oil droplets, but the threshold value of agitation speed (in this system 4000 rpm/min) does exist and that is what strongly increases break-up of oil droplets. The higher agitation rate resulted in smaller size of microcapsules (mean diameter decreasing from 5.6 to 4.9 µm for primary capsules and from 13.8 to 9.8 µm for secondary capsules) and with a narrower size distribution. The last mode of encapsulation allows the more effective use the shell material for encapsulating of larger amount of oil.

  9. 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. Copyright © 2015. Published by Elsevier B.V.

  10. 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.

  11. A Novel Core-Shell Microcapsule for Encapsulation and 3D Culture of Embryonic Stem Cells

    PubMed Central

    Zhang, Wujie; Zhao, Shuting; Rao, Wei; Snyder, Jedidiah; Choi, Jung K.; Wang, Jifu; Khan, Iftheker A.; Saleh, Navid B.; Mohler, Peter J.; Yu, Jianhua; Hund, Thomas J.; Tang, Chuanbing; He, Xiaoming

    2013-01-01

    In this study, we report the preparation of a novel microcapsule of ~ 100 μm with a liquid (as compared to solid-like alginate hydrogel) core and an alginate-chitosan-alginate (ACA) shell for encapsulation and culture of embryonic stem (ES) cells in the miniaturized 3D space of the liquid core. Murine R1 ES cells cultured in the microcapsules were found to survive (> 90%) well and proliferate to form either a single aggregate of pluripotent cells or embryoid body (EB) of more differentiated cells in each microcapsule within 7 days, dependent on the culture medium used. This novel microcapsule technology allows massive production of the cell aggregates or EBs of uniform size and controllable pluripotency, which is important for the practical application of stem cell based therapy. Moreover, the semipermeable ACA shell was found to significantly reduce immunoglobulin G (IgG) binding to the encapsulated cells by up to 8.2 times, compared to non-encapsulated cardiac fibroblasts, mesenchymal stem cells, and ES cells. This reduction should minimize inflammatory and immune responses induced damage to the cells implanted in vivo becasue IgG binding is an important first step of the undesired host responses. Therefore, the ACA microcapsule with selective shell permeability should be of importance to advance the emerging cell-based medicine. PMID:23505611

  12. The study of a fluorescent biosensor based on polyelectrolyte microcapsules with encapsulated glucose oxidase

    NASA Astrophysics Data System (ADS)

    Kazakova, L. I.; Sirota, N. P.; Sirota, T. V.; Shabarchina, L. I.

    2017-09-01

    A fluorescent biosensor is synthesized and described. The biosensor consists of polyelectrolyte microcapsules with glucose oxidase (GOx) entrapped in the cavities and an oxygen-sensitive fluorescent indicator Ru(dpp) immobilized in shells, where Ru(dpp) is tris(4,7-diphenyl-1,10-phenanthroline)ruthenium(II) dichloride. The theoretical activity of the encapsulated GOx and the effect storage time and medium composition have on the stability of sensor microcapsules are determined from polarographic measurements. No change in the activity of the encapsulated enzyme and or its loss to the storage medium are detected over the test period. The dispersion medium (water or a phosphate buffer) are shown to have no effect on the activity of microcapsules with immobilized GOx. The described optical sensor could be used as an alternative to electrochemical sensors for in vitro determination of glucose in the clinically important range of concentrations (up to 10 mmol/L).

  13. Cytoprotective alginate/polydopamine core/shell microcapsules in microbial encapsulation.

    PubMed

    Kim, Beom Jin; Park, Taegyun; Moon, Hee Chul; Park, So-Young; Hong, Daewha; Ko, Eun Hyea; Kim, Ji Yup; Hong, Jong Wook; Han, Sang Woo; Kim, Yang-Gyun; Choi, Insung S

    2014-12-22

    Chemical encapsulation of microbes in threedimensional polymeric microcapsules promises various applications, such as cell therapy and biosensors, and provides a basic platform for studying microbial communications. However, the cytoprotection of microbes in the microcapsules against external aggressors has been a major challenge in the field of microbial microencapsulation, because ionotropic hydrogels widely used for microencapsulation swell uncontrollably, and are physicochemically labile. Herein, we developed a simple polydopamine coating for obtaining cytoprotective capability of the alginate capsule that encapsulated Saccharomyces cerevisiae. The resulting alginate/ polydopamine core/shell capsule was mechanically tough, prevented gel swelling and cell leakage, and increased resistance against enzymatic attack and UV-C irradiation. We believe that this multifunctional core/shell structure will provide a practical tool for manipulating microorganisms inside the microcapsules. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. 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. Copyright © 2015 Elsevier Ltd. All rights reserved.

  15. Encapsulation of basic fibroblast growth factor by polyelectrolyte multilayer microcapsules and its controlled release for enhancing cell proliferation.

    PubMed

    She, Zhen; Wang, Chunxia; Li, Jun; Sukhorukov, Gleb B; Antipina, Maria N

    2012-07-09

    Basic fibroblast growth factor (FGF2) is an important protein for cellular activity and highly vulnerable to environmental conditions. FGF2 protected by heparin and bovine serum albumin was loaded into the microcapsules by a coprecipitation-based layer-by-layer encapsulation method. Low cytotoxic and biodegradable polyelectrolytes dextran sulfate and poly-L-arginine were used for capsule shell assembly. The shell thickness-dependent encapsulation efficiency was measured by enzyme-linked immunosorbent assay. A maximum encapsulation efficiency of 42% could be achieved by microcapsules with a shell thickness of 14 layers. The effects of microcapsule concentration and shell thickness on cytotoxicity, FGF2 release kinetics, and L929 cell proliferation were evaluated in vitro. The advantage of using microcapsules as the carrier for FGF2 controlled release for enhancing L929 cell proliferation was analyzed.

  16. Preparation and characterization of monodisperse microcapsules with alginate and bentonite via external gelation technique encapsulating Pseudomonas putida Rs-198.

    PubMed

    Li, Xuan; Wu, Zhansheng; He, Yanhui; Ye, Bang-Ce; Wang, Jun

    2017-10-01

    This paper evaluated the external gelation technique for preparing microcapsules. The microcapsules were consisted of Pseudomonas putida Rs-198 (Rs-198) core and sodium alginate (NaAlg)-bentonite (Bent) shell. Different emulsification rotation speeds and core/shell ratios were used to prepare the microcapsules of each formulation. The near-spherical microcapsules were monodisperse with a mean diameter of 25-100 μm and wrinkled surfaces. Fourier transform infrared spectrophotometry (FTIR) and thermogravimetric analysis (TGA) revealed the physical mixture of the wall material and the superior thermal stability of the microcapsules. Percentage yield, water content, and encapsulation efficiency were evaluated and correlated with the changes in emulsification rotation speed and core/shell ratio. In vitro release experiments demonstrated that 60% of the bacteria were released from the NaAlg-Bent microcapsules within three days. Considerably better survival was observed for encapsulated cells compared to free cells, especially in pH 4.0 and 10.0. In summary, the desired properties of microcapsules can be obtained by external gelation technique and the microcapsules on the bacteria had a good protective effect.

  17. 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.

  18. Encapsulation of factor IX–engineered mesenchymal stem cells in fibrinogen–alginate microcapsules enhances their viability and transgene secretion

    PubMed Central

    Sayyar, Bahareh; Dodd, Megan; Wen, Jianping; Ma, Shirley; Marquez-Curtis, Leah; Janowska-Wieczorek, Anna

    2012-01-01

    Cell microencapsulation holds significant promise as a strategy for cellular therapies; however, inadequate survival and functionality of the enclosed cells limit its application in hemophilia treatment. Here, we evaluated the use of alginate-based microcapsules to enhance the viability and transgene secretion of human cord blood–derived mesenchymal stem cells in three-dimensional cultures. Given the positive effects of extracellular matrix molecules on mesenchymal stem cell growth, we tested whether fibrinogen-supplemented alginate microcapsules can improve the efficiency of encapsulated factor IX–engineered mesenchymal stem cells as a treatment of hemophilia B. We found that fibrinogen-supplemented alginate microcapsules (a) significantly enhanced the viability and proliferation of factor IX–engineered mesenchymal stem cells and (b) increased factor IX secretion by mesenchymal stem cells compared to mesenchymal stem cells in nonsupplemented microcapsules. Moreover, we observed the osteogenic, but not chondrogenic or adipogenic, differentiation capability of factor IX–engineered cord blood mesenchymal stem cells and their efficient factor IX secretion while encapsulated in fibrinogen-supplemented alginate microcapsules. Thus, the use of engineered mesenchymal stem cells encapsulated in fibrinogen-modified microcapsules may have potential application in the treatment of hemophilia or other protein deficiency diseases. PMID:23316273

  19. Encapsulation of factor IX-engineered mesenchymal stem cells in fibrinogen-alginate microcapsules enhances their viability and transgene secretion.

    PubMed

    Sayyar, Bahareh; Dodd, Megan; Wen, Jianping; Ma, Shirley; Marquez-Curtis, Leah; Janowska-Wieczorek, Anna; Hortelano, Gonzalo

    2012-01-01

    Cell microencapsulation holds significant promise as a strategy for cellular therapies; however, inadequate survival and functionality of the enclosed cells limit its application in hemophilia treatment. Here, we evaluated the use of alginate-based microcapsules to enhance the viability and transgene secretion of human cord blood-derived mesenchymal stem cells in three-dimensional cultures. Given the positive effects of extracellular matrix molecules on mesenchymal stem cell growth, we tested whether fibrinogen-supplemented alginate microcapsules can improve the efficiency of encapsulated factor IX-engineered mesenchymal stem cells as a treatment of hemophilia B. We found that fibrinogen-supplemented alginate microcapsules (a) significantly enhanced the viability and proliferation of factor IX-engineered mesenchymal stem cells and (b) increased factor IX secretion by mesenchymal stem cells compared to mesenchymal stem cells in nonsupplemented microcapsules. Moreover, we observed the osteogenic, but not chondrogenic or adipogenic, differentiation capability of factor IX-engineered cord blood mesenchymal stem cells and their efficient factor IX secretion while encapsulated in fibrinogen-supplemented alginate microcapsules. Thus, the use of engineered mesenchymal stem cells encapsulated in fibrinogen-modified microcapsules may have potential application in the treatment of hemophilia or other protein deficiency diseases.

  20. Simulating tissue oxygenation by encapsulating hemoglobin in polymer microcapsules (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Liu, Guangli; Wu, Qiang; Shen, Shuwei; Zhao, Gang; Dong, Erbao; Xu, Ronald X.

    2017-03-01

    We describe a combination of liquid-jet microencapsulation and molding techniques to fabricate tissue-simulating phantoms that mimick functional characteristics of tissue oxygen saturation (StO2). Chicken hemoglobin (Hb) was encapsulated inside a photocurable resin by a coaxial flow focusing process. The microdroplets were cured by ultraviolet (UV) illumination to form Hb loaded polymersome microdroplets. The microdroplets were further freeze-dried to form semipermeable solid microcapules with an outer transparent polymeric shell and an inner core of Hb. The diameter of the microcapsules ranged from 50 to100 μm. The absorption spectrum of the microcapsules was measured by a UV/VIS spectrophotometer over a wavelength range from 400 nm to 1100 nm. To fabricate the tissue-simulating phantom, the Hb loaded microcapsules were dispersed in transparent polydimethylsiloxane (PDMS). The optical properties of the phantom were determined by an vertical double integrating sphere with a reconstruction algorithm. The experimental results showed that the tissue-simulating phantom exhibited the spectral characteristics closely resembling that of oxy-hemoglobin. The phantom had a long-term optical stability when stored in 4 ℃, indicating that microencapsulation effectively protected Hb and improved its shelf time. With the Hb loaded microcapsules, we will produce skin-simulating phantoms for quantitative validation of multispectral imaging techniques. To the best of the authors' knowledge, no solid phantom is able to mimick living tissue oxygenation with good agreement. Therefore, our work provided an engineering platform for validating and calibrating spectral optical devices in biomedical applications.

  1. 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.

  2. Sustained and therapeutic levels of human factor IX in hemophilia B mice implanted with microcapsules: key role of encapsulated cells.

    PubMed

    Wen, Jianping; Vargas, Andrew Gómez; Ofosu, Frederick A; Hortelano, Gonzalo

    2006-03-01

    A gene therapy delivery system based on microcapsules enclosing recombinant cells engineered to secrete a therapeutic protein was explored in this study. In order to prevent immune rejection of the delivered cells, they were enclosed in non-antigenic biocompatible alginate microcapsules prior to being implanted intraperitoneally into mice. We have shown that encapsulated C2C12 myoblasts can temporarily deliver therapeutic levels of factor IX (FIX) in mice, but the C2C12 myoblasts elicited an immune response to FIX. In this study we report the use of mouse fetal G8 myoblasts secreting hFIX in hemophilia mice. Mouse G8 myoblasts were transduced with MFG-FIX vector. A pool of recombinant G8 myoblasts secreting approximately 1500 ng hFIX/10(6) cells/24 h in vitro were enclosed in biocompatible alginate microcapsules and implanted intraperitoneally into immunocompetent C57BL/6 and hemophilic mice. Circulating levels of hFIX in treated mice reached approximately 400 ng/ml for at least 120 days (end of experiment). Interestingly, mice treated with encapsulated G8 myoblasts did not develop anti-hFIX antibodies. Activated partial thromboplastin time (APTT) of plasmas obtained from treated hemophilic mice was reduced from 107 to 82 sec on day 60 post-treatment, and whole blood clotting time (WBCT) was also corrected from 7-9 min before treatment to 3-5 min following microcapsule implantation. Further, mice were protected against bleeding following major trauma. Thus, the FIX delivery in vivo was biologically active. Our findings suggest that the type of cells encapsulated play a key role in the generation of immune responses against the transgene. Further, a judicious selection of encapsulated cells is critical for achieving sustained gene expression. Our findings support the feasibility of encapsulated G8 myoblasts as a gene therapy approach for hemophilia B.

  3. Encapsulation of Biological and Chemical Agents for Plant Nutrition and Protection: Chitosan/Alginate Microcapsules Loaded with Copper Cations and Trichoderma viride.

    PubMed

    Vinceković, Marko; Jalšenjak, Nenad; Topolovec-Pintarić, Snježana; Đermić, Edyta; Bujan, Marija; Jurić, Slaven

    2016-11-02

    Novel chitosan/alginate microcapsules simultaneously loaded with copper cations and Trichoderma viride have been prepared and characterized. Information about the intermolecular interactions between biopolymers and bioactive agents was obtained by Fourier transform infrared spectroscopy. Encapsulation of T. viride spores and the presence of copper cations in the same compartment does not inhibit their activity. Microcapsule loading capacity and efficiency as well as swelling behavior and release depend on both the size of the microcapsule and bioactive agents. The in vitro copper cation release profile was fitted to a Korsmeyer-Peppas empirical model. Fickian diffusion was found to be a rate-controlling mechanism of release from smaller microcapsules, whereas anomalous transport kinetics controlled release from larger microcapsules. The T. viride spore release profile exhibited exponential release over the initial lag time. The results obtained opened perspectives for the future use of chitosan/alginate microcapsules simultaneously loaded with biological and chemical agents in plant nutrition and protection.

  4. Novel Fabric Containing Microcapsules of Chemical Decontaminants Encapsulated within Semipermeable Polymers.

    DTIC Science & Technology

    The invention concerns novel clothing fabrics containing microcapsules in a resin finish comprising reactive chemical decontamination agents...allowing the toxic chemicals to diffuse into the microcapsules where they undergo irreversible detoxifying chemical reactions.

  5. 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.

  6. ENCAPSULATED AEROSOLS

    DTIC Science & Technology

    acetate, polymerized rapidly and produced some polymer film encapsulation of the aerosol droplets. A two-stage microcapsule generator was designed...encapsulating material, the generator also produced microcapsules of dibutyl phosphite in polyethylene, nitrocellulose, and natural rubber.

  7. 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

  8. Microcapsule production employing chickpea or lentil protein isolates and maltodextrin: physicochemical properties and oxidative protection of encapsulated flaxseed oil.

    PubMed

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

    2013-08-15

    Flaxseed oil was microencapsulated, employing a wall material matrix of either chickpea (CPI) or lentil protein isolate (LPI) and maltodextrin, followed by freeze-drying. Effects of oil concentration (5.3-21.0%), protein source (CPI vs. LPI) and maltodextrin type (DE 9 and 18) and concentration (25.0-40.7%), on both the physicochemical characteristics and microstructure of the microcapsules, were investigated. It was found that an increase in emulsion oil concentration resulted in a concomitant increase in oil droplet diameter and microcapsule surface oil content, and a decrease in oil encapsulation efficiency. Optimum flaxseed oil encapsulation efficiency (∼83.5%), minimum surface oil content (∼2.8%) and acceptable mean droplet diameter (3.0 μm) were afforded with 35.5% maltodextrin-DE 9 and 10.5% oil. Microcapsules, formed by employing these experimental conditions, showed a protective effect against oxidation versus free oil over a storage period of 25 d at room temperature.

  9. Cell-matrix Interactions of Factor IX (FIX)-engineered human mesenchymal stromal cells encapsulated in RGD-alginate vs. fibrinogen-alginate microcapsules.

    PubMed

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

    2014-04-01

    The success of cell microencapsulation technology in tissue engineering and protein delivery applications depends on the viability and functionality of the encapsulated cells, which in turn are dependent upon cell/matrix interactions. In this work, we compared the viability of cord blood-derived mesenchymal stromal cells (CB MSCs), engineered to secrete factor IX (FIX) for hemophilia treatment, and encapsulated in arginine-glycine-aspartate (RGD)-alginate versus fibrinogen-alginate microcapsules. We evaluated the effect of the biomimetic matrix on cell attachment, proliferation, and secretion of FIX. Compared with nonsupplemented alginate matrix, RGD-alginate significantly enhanced the viability of the encapsulated MSCs. Further, cells in RGD-alginate displayed distinct attachment morphology, thus suggesting that RGD-alginate can potentially be used for the encapsulation of MSCs in tissue engineering applications that require enhanced cell attachment and viability. However, our data also showed that RGD-alginate microcapsules, in contrast to fibrinogen-alginate microcapsules, did not significantly improve cell proliferation of or FIX secretion by encapsulated MSCs. Our findings suggest that evidence of cell attachment alone may not accurately predict the functionality of cells in biomimetic microcapsules.

  10. 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

  11. The effect of surfactant chain length on the morphology of poly(methyl methacrylate) microcapsules for fragrance oil encapsulation.

    PubMed

    Tasker, Alison Louise; Hitchcock, James Paul; He, Ling; Baxter, Elaine Alice; Biggs, Simon; Cayre, Olivier Jean

    2016-12-15

    The solvent evaporation method for producing microcapsules relies upon the correct wetting conditions between the three phases involved in the synthesis to allow core-shell morphologies to form. By measuring the interfacial tensions between the oil, polymer and aqueous phases, spreading coefficients can be calculated, allowing the capsule morphology to be predicted. In this work we explore the effect of surfactant chain length on capsule morphology using poly(methyl methacrylate) as the polymer and hexadecane as the core. We compared the predicted morphologies obtained using the polymer as a solid, and the polymer dissolved in dichloromethane to represent the point at which capsule formation begins. We found that using the polymer in its final, solid form gave predictions which were more consistent with our observations. The method was applied to successfully predict the capsule morphologies obtained when commercial fragrance oils were encapsulated. Copyright © 2016. Published by Elsevier Inc.

  12. Preparation of a water-in-oil-in-water (W/O/W) type microcapsules by a single-droplet-drying method and change in encapsulation efficiency of a hydrophilic substance during storage.

    PubMed

    Adachi, Shuji; Imaoka, Hanaho; Hasegawa, Yuri; Matsuno, Ryuichi

    2003-06-01

    Microcapsules of a water-in-oil-in-water (W/O/W) emulsion, which contained a hydrophilic substance, 1,3,6,8-pyrenetetrasulfonic acid tetrasodium salt (PTSA), in its inner aqueous phase, was prepared by hot-air-drying or freeze-drying the emulsion using a single-droplet-drying method. Pullulan, maltodextrin, or gum arabic was used as a wall material, and the oily phase was tricaprylin, oleic acid, olive oil, or a mixture of tricaprylin and olive oil. An encapsulation efficiency higher than 0.95 was reached except for the microcapsules prepared using gum arabic and oleic acid. The hot-air-dried microcapsules were generally more stable than the freeze-dried microcapsules at 37 degrees C and various relative humidities. The stability was higher for the microcapsules with tricaprylin as the oily phase than for the microcapsules with oleic acid. The higher stability of the microcapsules with tricaprylin would be ascribed to the lower partition coefficient of PTSA to the oily phase. There was a tendency for the stability to be higher at lower relative humidity for both the hot-air- and freeze-dried microcapsules. The volumetric fraction of olive oil in its mixture with tricaprylin did not significantly affect either the encapsulation efficiency or the stability of the hot-air-dried microcapsules.

  13. Encapsulation of albumin in self-assembled layer-by-layer microcapsules: comparison of co-precipitation and adsorption techniques.

    PubMed

    Labala, Suman; Mandapalli, Praveen Kumar; Bhatnagar, Shubhmita; Venuganti, Venkata Vamsi Krishna

    2015-01-01

    The objective of this study is to prepare and characterize polymeric self-assembled layer-by-layer microcapsules (LbL-MC) to deliver a model protein, bovine serum albumin (BSA). The aim is to compare the BSA encapsulation in LbL-MC using co-precipitation and adsorption methods. In co-precipitation method, BSA was co-precipitated with growing calcium carbonate particles to form a core template. Later, poly(styrene sulfonate) and poly(allylamine hydrochloride) were sequentially adsorbed onto the CaCO3 templates. In adsorption method, preformed LbL-MC were incubated with BSA and encapsulation efficiency is optimized for pH and salt concentration. Free and BSA-encapsulated LbL-MC were characterized using Zetasizer, scanning electron microscopy (SEM), Fourier transform infrared spectroscopy and differential scanning calorimeter. Later, in vitro release studies were performed using dialysis membrane method at pH 4, 7.4 and 9. Results from Zetasizer and SEM showed free LbL-MC with an average size and zeta-potential of 2.0 ± 0.6 μm and 8.1 ± 1.9 mV, respectively. Zeta-potential of BSA-loaded LbL-MC was (-)7.4 ± 0.7 mV and (-)5.7 ± 1.0 mV for co-precipitation and adsorption methods, respectively. In adsorption method, BSA encapsulation in LbL-MC was found to be greater at pH 6.0 and 0.2 M NaCl. Co-precipitation method provided four-fold greater encapsulation efficiency (%) of BSA in LbL-MC compared with adsorption method. At pH 4, the BSA release from LbL-MC was extended up to 120 h. Polyacrylamide gel electrophoresis showed that BSA encapsulated in LBL-MC through co-precipitation is stable toward trypsin treatment. In conclusion, co-precipitation method provided greater encapsulation of BSA in LbL-MC. Furthermore, LbL-MC can be developed as carriers for pH-controlled protein delivery.

  14. 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. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Live encapsulated Lactobacillus acidophilus cells in yogurt for therapeutic oral delivery: preparation and in vitro analysis of alginate-chitosan microcapsules.

    PubMed

    Urbanska, Aleksandra Malgorzata; Bhathena, Jasmine; Prakash, Satya

    2007-09-01

    Targeted delivery of live microencapsulated bacterial cells has strong potential for application in treating various diseases, including diarrhea, kidney failure, liver failure, and high cholesterol, among others. This study investigates the potential of microcapsules composed of two natural polymers, alginate and chitosan (AC), and the use of these artificial cells in yogurt for delivery of probiotic Lactobacillus acidophilus bacterial live cells. Results show that the integrity of AC microcapsules was preserved after 76 h of mechanical shaking in MRS broth and after 12 h and 24 h in simulated gastric and intestinal fluids. Using an in vitro computer-controlled simulated human gastrointestinal (GI) model, we found 8.37 log CFU/mL of viable bacterial cells were present after 120 min of gastric exposure and 7.96 log CFU/mL after 360 min of intestinal exposure. In addition, AC microcapsules composed of chitosan 10 and 100 at various concentrations were subjected to 4-week storage in 2% milk fat yogurt or 0.85% physiological solution. It was found that 9.37 log CFU/mL of cells encapsulated with chitosan 10 and 8.24 log CFU/mL of cells encapsulated with chitosan 100 were alive after 4 weeks. The AC capsule composed of 0.5% chitosan 10 provided the highest bacterial survival of 9.11 log CFU/mL after 4 weeks. Finally, an investigation of bacterial viability over 72 h in different pH buffers yielded highest survival of 6.34 log CFU/mL and 10.34 log CFU/mL at pH 8 for free and AC-encapsulated cells, respectively. We conclude from these findings that encapsulation allows delivery of a higher number of bacteria to desired targets in the GI tract and that microcapsules containing bacterial cells are good candidates for oral artificial cells for bacterial cell therapy.

  16. Matrix-assisted colloidosome reverse-phase layer-by-layer encapsulating biomolecules in hydrogel microcapsules with extremely high efficiency and retention stability.

    PubMed

    Mak, Wing Cheung; Bai, Jianhao; Chang, Xiang Yun; Trau, Dieter

    2009-01-20

    The layer-by-layer (LbL) polyelectrolyte self-assembly encapsulation method has attracted much interest because of its versatility to use various polymers for capsule formation, ability to encapsulate different templates, and capability to control capsule permeability. Traditionally, the LbL method was performed in water as solvent and limited to poorly or non-water-soluble templates. Using the matrix-assisted LbL method, complex mixtures of water-soluble proteins or DNA could be encapsulated within agarose microbeads templates but leakage of biomolecules into the water phase during the LbL process results in low encapsulation efficiency. Recently, the reverse-phase LbL (RP-LbL) method was introduced to perform LbL and encapsulation of water-soluble templates in organic solvents, thus preventing the templates from dissolving and allowing high encapsulation efficiency. However, encapsulation of complex mixtures of biomolecules or other substances with quantitative encapsulation efficiency remained impossible. Here we present a new approach for encapsulation of biomolecules or complex mixtures thereof with almost 100% encapsulation efficiency. The ability of our method to achieve high encapsulation efficiency arises from the combination of two strategies. (1) Using microparticles as surface stabilizer to create stable biomolecule-loaded hydrogel microbeads, termed matrix-assisted colloidosome (MAC), that are able to disperse in oil and organic solvents. (2) Using the RP-LbL method to fabricate polymeric capsule "membranes", thereby preventing diffusion of the highly water-soluble biomolecules. Using an oil phase during emulsification and an organic solvent phase during encapsulation could completely prevent leakage of water-soluble biomolecules and almost 100% encapsulation efficiency is achieved. Microcapsules fabricated with our method retained nearly 100% of encapsulated proteins during a 7 day incubation period in water. The method was demonstrated on model

  17. 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

  18. 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.

  19. Oral delivery of probiotic expressing M cell homing peptide conjugated BmpB vaccine encapsulated into alginate/chitosan/alginate microcapsules.

    PubMed

    Jiang, Tao; Singh, Bijay; Maharjan, Sushila; Li, Hui-Shan; Kang, Sang-Kee; Bok, Jin-Duck; Cho, Chong-Su; Choi, Yun-Jaie

    2014-11-01

    Oral administration of live probiotics as antigen delivery vectors is a promising approach in vaccine development. However, the low survival of probiotics in the gastrointestinal tract limits this approach. Therefore, the aim of this study was the encapsulation of probiotic expressing vaccine into alginate/chitosan/alginate (ACA) microcapsules (MCs) for efficient oral vaccine delivery. Here, recombinant Lactobacillus plantarum 25 (LP25) expressing M cell homing peptide fused BmpB protein was used as a model probiotic. 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 2h. Encapsulated LP25 was completely released from ACA MCs in SIF within 12h. When stored at room temperature (RT) or 4°C, the viability of LP25 in ACA MCs was higher than free LP25. Interestingly, the viability of LP25 in ACA MCs at 4°C for 5weeks was above 58%, whereas viability of free LP25 stored at RT up to 5weeks was zero. After 4weeks from the first immunization, LP25-M-BmpB-loaded ACA MCs induced a stronger BmpB-specific IgG and IgA production in mice. Collectively, these findings suggest that encapsulation of probiotic by ACA MCs is a promising delivery system for oral administration of probiotic expressing vaccine.

  20. 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.

  1. 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.

  2. Reconfigurable Photonic Capsules Containing Cholesteric Liquid Crystals with Planar Alignment.

    PubMed

    Lee, Sang Seok; Kim, Su Kyung; Won, Jong Chan; Kim, Yun Ho; Kim, Shin-Hyun

    2015-12-07

    Cholesteric liquid crystals (CLCs) reflect selected wavelengths of light owing to their periodic helical structures. The encapsulation of CLCs leads to photonic devices that can be easily processed and might be used as stand-alone microsensors. However, when CLCs are enclosed by polymeric membranes, they usually lose their planar alignment, leading to a deterioration of the optical performance. A microfluidics approach was employed to integrate an ultrathin alignment layer into microcapsules to separate the CLC core and the elastomeric solid membrane using triple-emulsion drops as the templates. The thinness of the alignment layer provides high lubrication resistance, preserving the layer integrity during elastic deformation of the membrane. The CLCs in the microcapsules can thus maintain their planar alignment, rendering the shape and optical properties highly reconfigurable. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Long-term stability of CdSe/CdZnS quantum dot encapsulated in a multi-lamellar microcapsule

    NASA Astrophysics Data System (ADS)

    Park, Sang-Yul; Kim, Hyo-Sun; Yoo, Jeseung; Kwon, Suyong; Shin, Tae Joo; Kim, Kyungnam; Jeong, Sohee; Seo, Young-Soo

    2015-07-01

    We developed a novel and easy encapsulation method for quantum dots (QDs) using a partially oxidized semi-crystalline polymeric material which forms a micron-sized granule with a multi-lamellar structure from a dilute solution. The QDs were highly dispersed in the granule in such a way that they were adsorbed on the lamella with ˜12 nm spacing followed by lamellar stacking. The QDs were heavily loaded into the granule to 16.7 wt% without aggregation, a process which took only a few minutes. We found that the quantum yield of the QDs was not degraded after the encapsulation. The encapsulated QD-silicone composite exhibited excellent long-term photo- and thermal stability with its initial photoluminescence intensity maintained after blue LED light radiation for 67 days and storage at 85 °C and 85% relative humidity for 119 days.

  4. Long-term stability of CdSe/CdZnS quantum dot encapsulated in a multi-lamellar microcapsule.

    PubMed

    Park, Sang-Yul; Kim, Hyo-Sun; Yoo, Jeseung; Kwon, Suyong; Shin, Tae Joo; Kim, Kyungnam; Jeong, Sohee; Seo, Young-Soo

    2015-07-10

    We developed a novel and easy encapsulation method for quantum dots (QDs) using a partially oxidized semi-crystalline polymeric material which forms a micron-sized granule with a multi-lamellar structure from a dilute solution. The QDs were highly dispersed in the granule in such a way that they were adsorbed on the lamella with ∼12 nm spacing followed by lamellar stacking. The QDs were heavily loaded into the granule to 16.7 wt% without aggregation, a process which took only a few minutes. We found that the quantum yield of the QDs was not degraded after the encapsulation. The encapsulated QD-silicone composite exhibited excellent long-term photo- and thermal stability with its initial photoluminescence intensity maintained after blue LED light radiation for 67 days and storage at 85 °C and 85% relative humidity for 119 days.

  5. Controlled-release of Bacillus thurigiensis formulations encapsulated in light-resistant colloidosomal microcapsules for the management of lepidopteran pests of Brassica crops

    PubMed Central

    Bashir, Oumar; Lemoyne, Pierre

    2016-01-01

    Bacillus thuringiensis (B. t.) based formulations have been widely used to control lepidopteran pests in agriculture and forestry. One of their weaknesses is their short residual activity when sprayed in the field. Using Pickering emulsions, mixtures of spores and crystals from three B. t. serovars were successfully encapsulated in colloïdosomal microparticles (50 μm) using innocuous chemicals (acrylic particles, sunflower oil, iron oxide nanoparticles, ethanol and water). A pH trigger mechanism was incorporated within the particles so that B. t. release occurred only at pH > 8.5 which corresponds to the midgut pH of the target pests. Laboratory assays performed on Trichoplusia ni (T. ni) larvae demonstrated that the microencapsulation process did not impair B. t. bioactivity. The best formulations were field-tested on three key lepidopteran pests that attack Brassica crops, i.e., the imported cabbageworm, the cabbage looper and the diamondback moth. After 12 days, the mean number of larvae was significantly lower in microencapsulated formulations than in a commercial B. t. formulation, and the effect of microencapsulated formulations was comparable to a chemical pesticide (lambda-cyhalothrin). Therefore, colloïdosomal microcapsule formulations successfully extend the bioactivity of B. t. for the management of lepidopteran pests of Brassica crops. PMID:27761325

  6. 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%.

  7. 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

    2016-06-07

    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%.

  8. Controlled-release of Bacillus thurigiensis formulations encapsulated in light-resistant colloidosomal microcapsules for the management of lepidopteran pests of Brassica crops.

    PubMed

    Bashir, Oumar; Claverie, Jerome P; Lemoyne, Pierre; Vincent, Charles

    2016-01-01

    Bacillus thuringiensis (B. t.) based formulations have been widely used to control lepidopteran pests in agriculture and forestry. One of their weaknesses is their short residual activity when sprayed in the field. Using Pickering emulsions, mixtures of spores and crystals from three B. t. serovars were successfully encapsulated in colloïdosomal microparticles (50 μm) using innocuous chemicals (acrylic particles, sunflower oil, iron oxide nanoparticles, ethanol and water). A pH trigger mechanism was incorporated within the particles so that B. t. release occurred only at pH > 8.5 which corresponds to the midgut pH of the target pests. Laboratory assays performed on Trichoplusia ni (T. ni) larvae demonstrated that the microencapsulation process did not impair B. t. bioactivity. The best formulations were field-tested on three key lepidopteran pests that attack Brassica crops, i.e., the imported cabbageworm, the cabbage looper and the diamondback moth. After 12 days, the mean number of larvae was significantly lower in microencapsulated formulations than in a commercial B. t. formulation, and the effect of microencapsulated formulations was comparable to a chemical pesticide (lambda-cyhalothrin). Therefore, colloïdosomal microcapsule formulations successfully extend the bioactivity of B. t. for the management of lepidopteran pests of Brassica crops.

  9. Triple Emulsion Drops with An Ultrathin Water Layer: High Encapsulation Efficiency and Enhanced Cargo Retention in Microcapsules.

    PubMed

    Choi, Chang-Hyung; Lee, Hyomin; Abbaspourrad, Alireza; Kim, June Hwan; Fan, Jing; Caggioni, Marco; Wesner, Chris; Zhu, Taotao; Weitz, David A

    2016-05-01

    Triple emulsion drops with an ultrathin water layer are developed to achieve high encapsulation efficiency of hydrophobic cargo in a hydrophobic polymeric shell, directly dispersed in water. Furthermore, enhanced retention of volatile hydrophobic cargo is achieved by forming a hydrogel network within this water layer that serves as a physical barrier.

  10. Biofilm-like Lactobacillus rhamnosus probiotics encapsulated in alginate and carrageenan microcapsules exhibiting enhanced thermotolerance and freeze-drying resistance.

    PubMed

    Cheow, Wean Sin; Hadinoto, Kunn

    2013-09-09

    Microcapsules containing high-density biofilm-like Lactobacillus rhamnosus probiotics, in place of planktonic cells, are developed in order to enhance the cell viability upon exposures to stresses commonly encountered during food lifecycle (i.e., heating, freeze-drying, refrigerated storage, and acid). The high-density (HD) capsules are prepared by in situ cultivation of the planktonic cells in the confined space of polysaccharide-based capsules (i.e., chitosan-coated alginate and carrageenan capsules). Compared to their planktonic counterparts, the HD capsules exhibit higher freeze-drying resistance (~40×) and higher thermotolerance upon prolonged wet heat exposures at 60 and 70 °C (~12-8000×), but not at higher temperatures even for short exposures (i.e., 80 and 100 °C). The enhanced viability of the HD capsules, however, is not observed during the refrigerated storage and exposure to the simulated gastric juice. The alginate capsules are superior to carrageenan owed to their better cell release profile in the simulated intestinal juice and storage viability.

  11. 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.

  12. 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.

  13. 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.

  14. Microcapsules with three orthogonal reactive sites

    PubMed Central

    Mason, Brian P.; Hira, Steven M.; Strouse, Geoffrey F.; McQuade, D. Tyler

    2009-01-01

    Polymeric microcapsules containing reactive sites on the shell surface and two orthogonally reactive polymers encapsulated within the interior are selectively labeled. The capsules provide three spatially separate and differentially reactive sites. Confocal fluorescence microscopy is used to characterize the distribution of labels. Polymers encapsulated are distributed homogeneously within the core and do not interact with the shell even when oppositely charged. PMID:19254010

  15. Encapsulation of high temperature molten salts

    DOEpatents

    Oxley, James D.; Mathur, Anoop Kumar

    2017-05-16

    The present disclosure relates to a method of encapsulating microcapsules containing relatively high temperature phase change materials and the microcapsules so produced. The microcapsules are coated with an inorganic binder, film former and an inorganic filler. The microcapsules may include a sacrificial layer that is disposed between the particle and the coating. The microcapsules may also include an inner coating layer, sacrificial layer and outer coating layer. The microcapsules are particularly useful for thermal energy storage in connection with, e.g., heat collected from concentrating solar collectors.

  16. 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

  17. Microencapsulation and controlled release of insulin from polylactic acid microcapsules.

    PubMed

    Lin, S Y; Ho, L T; Chiou, H L

    Insulin has been encapsulated in biodegradable polylactic acid microcapsules and non-biodegradable ethylcellulose microcapsules by using an emulsification-solvent evaporation process. Gelatin and polyvinylalcohol were used as protective colloids. The concentrations and types of protective colloids affecting the micromeritic properties and release behavior of insulin microcapsules were studied. The higher the concentration of protective colloids the smaller the particle size of microcapsules. The median diameter of microcapsules decreased with the increase of the viscosity of protective colloids. Scanning electron microscopic observations suggested that microcapsules prepared from higher concentrations of polyvinylalcohol solution resulted in a nonporous and compact surface on the microcapsules, compared to the porous microcapsules prepared from gelatin solution. The residual crystals and porous structure of microcapsules affected the release rate of microcapsules. After the initial burst effect the release rate of insulin from microcapsules was found to be constant, so that prolonged release was obtainable. Three percent of polyvinylalcohol was the best choice for the preparation of polylactic acid microcapsules.

  18. 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.

  19. 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.

  20. Nanostructured polysaccharidic microcapsules for intracellular release of cisplatin.

    PubMed

    Vergaro, Viviana; Papadia, Paride; Petrini, Paola; Fanizzi, Francesco Paolo; De Pascali, Sandra A; Baldassarre, Francesca; Pastorino, Laura; Ciccarella, Giuseppe

    2017-06-01

    Carbohydrate polimeric microcapsules were assembled using a LbL approach onto a CaCO3 core. The microcapsules were used to delivery the anticancer drug cisplatin into HeLa and MCF-7 cancer cell lines. Drug encapsulation, measured by ICP spectroscopy, was around 50% of the charging solution. Fluorimetric measurements showed an efficient cellular uptake of polysacchardic microcapsules in both cell lines. The drug-loaded capsules demonstrated a better efficiency against cell viability than the free drug. Specifically, the amount of platinum reaching genomic DNA was measured, showing that encapsulation improves the nuclear delivery of the drug for both cell lines.

  1. Preparation and characterization of coacervate microcapsules for the delivery of antimicrobial oyster peptides.

    PubMed

    Zhang, Li; Liu, Yezhou; Wu, Zhongchen; Chen, Haixu

    2009-03-01

    Oyster peptides-loaded alginate/chitosan/starch microcapsules were prepared using external gelation method and internal emulsion gelation method. The solution of oyster peptides complexes was encapsulated into the microcapsules, which endowed the microcapsules with intestine passive targeting properties. The swelling behavior, encapsulation efficiency, and release behavior of oyster peptides from the microcapsules at different pH values were investigated. The microcapsules exhibited sustained release of the peptides in intestinal medium, and the release rate could be regulated by the pH value: in simulated gastric fluid, the release rate was greatly decreased, and in simulated body fluid and intestinal fluid, the microcapsules exhibited a sustained release in 24 h with different release rates. The microspheres were characterized by Fourier transform infrared. The results suggested that the alginate/chitosan/starch microcapsules could be a suitable copolymeric carrier system for intestinal protein or peptides delivery in the intestine.

  2. Oil core microcapsules by inverse gelation technique.

    PubMed

    Martins, Evandro; Renard, Denis; Davy, Joëlle; Marquis, Mélanie; Poncelet, Denis

    2015-01-01

    A promising technique for oil encapsulation in Ca-alginate capsules by inverse gelation was proposed by Abang et al. This method consists of emulsifying calcium chloride solution in oil and then adding it dropwise in an alginate solution to produce Ca-alginate capsules. Spherical capsules with diameters around 3 mm were produced by this technique, however the production of smaller capsules was not demonstrated. The objective of this study is to propose a new method of oil encapsulation in a Ca-alginate membrane by inverse gelation. The optimisation of the method leads to microcapsules with diameters around 500 μm. In a search of microcapsules with improved diffusion characteristics, the size reduction is an essential factor to broaden the applications in food, cosmetics and pharmaceuticals areas. This work contributes to a better understanding of the inverse gelation technique and allows the production of microcapsules with a well-defined shell-core structure.

  3. 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

  4. 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.

  5. Targeted Self-Healing by Magnetically Guiding Microcapsules.

    PubMed

    Crall, Matthew D; Keller, Michael W

    2017-02-22

    Magnetically guided microcapsules are used to achieve self-healing with 1/10th of the healing components required using traditional self-healing approaches. Microcapsules are rendered responsive to magnetic fields by suspending magnetic nanoparticles in the core material. The nanoparticles are surface-modified to enable urea-formaldehyde encapsulation within a phenyl acetate core. Magnetic fields are used to guide the microcapsules to the expected fracture location in tapered double-cantilever beam (TDCB) epoxy specimens. This guiding method achieves an order of magnitude increase in local microcapsule concentration over controls, resulting in successful self-healing at microcapsule concentrations as low as 0.025 wt %. Additionally, the observed healing is both more consistent and significantly higher than that of control specimens, remaining relatively constant across all weight percentages tested.

  6. 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.

  7. Polyurea microcapsules in microfluidics: surfactant control of soft membranes.

    PubMed

    Polenz, Ingmar; Weitz, David A; Baret, Jean-Christophe

    2015-01-27

    Interfacial polymerization techniques offer a versatile route for microcapsule synthesis. We designed a microfluidic process to synthesize monodisperse polyurea microcapsules (PUMCs); the microcapsules are formed by an interfacial polymerization of isocyanate dissolved in the oil and an amine dissolved in water. We measure the mechanical properties of the capsule as well as transport properties through the membrane using two microfluidic methods. We show that the elasticity and the permeability of the shell are controlled by surfactant additives, added during the synthesis. The control of the nanostructure of the shell by surfactants provides new means to design encapsulation systems with tailored mechanical and physicochemical properties.

  8. 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.

  9. Preparation and evaluation of celecoxib-loaded microcapsules with self-microemulsifying core.

    PubMed

    Homar, Miha; Dreu, Rok; Kerc, Janez; Gasperlin, Mirjana

    2009-09-01

    The purpose of this study was to prepare alginate microcapsules with a self-microemulsifying system (SMES) containing celecoxib in the core. An Inotech IE-50 R encapsulator equipped with a concentric nozzle was used to prepare the microcapsules. The encapsulated SMES was shown to increase celecoxib solubility over that of the pure drug more than 400-fold. Microcapsules prepared with a high SMES:celecoxib ratio exhibited distinct core vesicles containing liquid SMES. By modifying the SMES and including an additional chitosan coating, drug loading in the range from 12-40% could be achieved with the degree of encapsulation ranging from 60-82%. Alginate microcapsules loaded with SMES and celecoxib showed increased dissolution rate of celecoxib over that of alginate microcapsules loaded with celecoxib or of the celecoxib alone. Compared to the previous report, drug loading capacity was significantly improved, enabling the formulation of dosage forms which are of suitable size for peroral application.

  10. Technological solutions for encapsulation

    NASA Astrophysics Data System (ADS)

    Trojanowska, Anna; Nogalska, Adrianna; Valls, Ricard Garcia; Giamberini, Marta; Tylkowski, Bartosz

    2017-07-01

    Encapsulation offers broad scope of applications. It can be used to deliver almost everything from advanced drugs to unique consumer sensory experiences; it could be also employed as a protection system or a sensing material. This cutting-edge technology undergoes rapid growth in both academic and industrial conditions. Research in this matter is continuing to find a new application of microcapsules as well as to improve the methods of their fabrication. Therefore, in this review, we focus on the art of the encapsulation technology to provide the readers with a comprehensive and in-depth understanding of up-to-day development of microcapsule preparation methods. Our goal is to help identify the major encapsulation processes and by doing so maximize the potential value of ongoing research efforts.

  11. The effect of coencapsulation of bovine insulin with cyclodextrins in ethylcellulose microcapsules.

    PubMed

    Graves, R L; Makoid, M C; Jonnalagadda, S

    2005-09-01

    Polymeric microcapsules have been widely investigated for protein delivery. Common problems include: low stability, low encapsulation efficiency, lack of uniformity, and burst release. Cyclodextrins (CDs) are known to enhance stability and solubility of proteins in solution. This research examines the effect of alpha-, beta-, and gamma-CDs on: (1) stability, (2) encapsulation, and (3) release of insulin from ethylcellulose microcapsules. All CDs improved thermal stability of insulin by lowering the enthalpy of unfolding by 16-52%. alpha- and gamma-CDs also increased the encapsulation efficiency of insulin and improved uniformity of the microcapsule formulations. Two mathematical models were proposed to account for insulin release and consisted of multiple zero order and first order input processes, and a single first order output process. All CDs decreased the initial burst release of insulin by up to 30%. This research demonstrates the potential for CDs to improve stability, uniformity, and encapsulation of proteins in microcapsule formulations.

  12. One-step fabrication of supramolecular microcapsules from microfluidic droplets.

    PubMed

    Zhang, Jing; Coulston, Roger J; Jones, Samuel T; Geng, Jin; Scherman, Oren A; Abell, Chris

    2012-02-10

    Although many techniques exist for preparing microcapsules, it is still challenging to fabricate them in an efficient and scalable process without compromising functionality and encapsulation efficiency. We demonstrated a simple one-step approach that exploits a versatile host-guest system and uses microfluidic droplets to generate porous microcapsules with easily customizable functionality. The capsules comprise a polymer-gold nanoparticle composite held together by cucurbit[8]uril ternary complexes. The dynamic yet highly stable micrometer-sized structures can be loaded in one step during capsule formation and are amenable to on-demand encapsulant release. The internal chemical environment can be probed with surface enhanced Raman spectroscopy.

  13. Pickering emulsion templated layer-by-layer assembly for making microcapsules.

    PubMed

    Li, Jian; Stöver, Harald D H

    2010-10-05

    Pickering emulsions stabilized by poly(sodium styrenesulfonate) (PSS) surface-modified LUDOX CL particles were used as templates for the layer-by-layer (LbL) deposition of polyelectrolytes and charged nanoparticles to form composite shells. The microcapsules resulting from repeated LbL coating with poly(diallyldimethylammonium chloride) (PDADMAC) and PSS had porous walls due to the loose arrangement of the original nanoparticle aggregates at the oil-water interface, leading to significant microcapsule rupture and low encapsulation efficiency. Microcapsules formed by coating with PDADMAC and anionic LUDOX HS nanoparticles led to dense walls and stronger microcapsules, suitable for microencapsulation of hydrophobic materials with a wide range of polarities.

  14. Local Anesthetic Microcapsulation.

    DTIC Science & Technology

    1982-06-14

    viscosities as disparate as R. S. V. 4.~O~6dl/g. ’ Microencapsulation of lidocaine (base) yielded 212-300 micron microcapsules with 50% in vitro drug...release in 6 hours; 150-212 micron microcapsules released 3-0% i7n-2 hours. Etidocaing and bupivacaine vo> 41’. were microencapsulated in a more...Etidocaine Microencapsulation 9 c. Bupivacaine Microencapsulation 12 3. In Vitro Drug Release from Microcapsules 15 a. Lidocaine (base) Release Studies

  15. Local Anesthetic Microcapsules.

    DTIC Science & Technology

    1981-04-15

    III Chemical Structure of Local Anesthetics 12 Table IV Processing Summary of Lidocaine Microencapsulation 15 Table V Lidocaine Microcapsule Size...Distribution 17 Table VI Processing Summary of Etidocaine Microencapsulation 18 Table VII Etidocaine Microcapsule Size Distribution 19 Table VIII Lidocaine...REPORT I PERIOD COVERED Annual Local Anesthetic Microcapsules 1 July 1980-30 March 1981 6. PERFORMING ORG. REPORT NUMBER 2106-1 7. AUTHOR() S

  16. Polymeric Microcapsule Arrays.

    DTIC Science & Technology

    1995-03-24

    support, microencapsulation and entrapment within a membrane/film or gel. The ideal enzyme immobilization method would (1) Employ mild chemical...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

  17. 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

  18. ENCAPSULATED AEROSOLS

    DTIC Science & Technology

    A two-stage microcapsule generator has been utilized to produce a variety of liquid core microcapsules . A number of operational and design changes...have been made to improve the performance of the generator and to increase its versatility. The generator has been used to provide microcapsules of...spraydried microcapsules . Nozzle design was found to be a critical parameter. (Author)

  19. Thermoresponsive microcapsules for controlled release of hydrophilic cargo

    NASA Astrophysics Data System (ADS)

    Amstad, Esther; Weitz, David

    2012-02-01

    Thermoresponsive microcapsules that collapse upon increasing the temperature above their lower critical solution temperature (LCST) such as poly(N-isopropyl acrylamide) (PNIPAM) capsules are well known. However, capsules consisting of thermoresponsive polymers that possess an upper critical solution temperature (UCST) and therefore swell upon increasing the temperature above their UCST are scarce. We will present a microfluidic method to assemble thermoresponsive poly([2-(methacryloyloxy)-ethyl]-dimethyl-[3-sulfopropyl-ammoniumhzdroxide) (PMEDSH) microcapsules that have UCST. These capsules are in a collapsed state at room temperature and become highly water permeable upon increasing the temperature above the UCST. To simultaneously allow for encapsulation of hydrophilic cargo and enable the water based polymerization reaction of the PMEDSH shell, these microcapsules are assembled as water/water/oil emulsions using capillary microfluidic devices. The resulting PMEDSH microcapsules are envisaged as delivery vehicles and microreactors that allow for temperature induced controlled release of hydrophilic cargo. .

  20. 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.

  1. 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.

  2. Isolation of fucoxanthin from Sargassum thunbergii and preparation of microcapsules based on palm stearin solid lipid core

    NASA Astrophysics Data System (ADS)

    Wang, Xuanxuan; Li, Hongyan; Wang, Fangqin; Xia, Guixue; Liu, Hongjun; Cheng, Xiaojie; Kong, Ming; Liu, Ya; Feng, Chao; Chen, Xiguang; Wang, Ying

    2017-03-01

    The objective of this study was to isolate fucoxanthin from Sargassum thunbergii and develop microcapsules with palm stearin as the solid lipid core for stability and efficient oral delivery of fucoxanthin. The microcapsules had smooth surfaces with the volume weighted mean diameter ( d 4.3) of 19.19 μm. Encapsulation efficiency and loading capacity of microcapsules with fucoxanthin were 98.3% and 0.04%, respectively. Moreover, the fucoxanthin in microcapsules presented higher stability than free fucoxanthin against light, humidity and temperature. Especially, the retention rates of fucoxanthin encapsulated in microcapsules reached 97.20% at 4°C, 92.60% at 25°C, 92.32% with the relative humidity of 33% and 92.60% in the dark. The cumulative amount of fucoxanthin released from microcapsules was 22.92% in simulated gastric fluid (SGF) and 56.55% in simulated intestinal fluid (SIF).

  3. Isolation of fucoxanthin from Sargassum thunbergii and preparation of microcapsules based on palm stearin solid lipid core

    NASA Astrophysics Data System (ADS)

    Wang, Xuanxuan; Li, Hongyan; Wang, Fangqin; Xia, Guixue; Liu, Hongjun; Cheng, Xiaojie; Kong, Ming; Liu, Ya; Feng, Chao; Chen, Xiguang; Wang, Ying

    2017-01-01

    The objective of this study was to isolate fucoxanthin from Sargassum thunbergii and develop microcapsules with palm stearin as the solid lipid core for stability and efficient oral delivery of fucoxanthin. The microcapsules had smooth surfaces with the volume weighted mean diameter (d 4.3) of 19.19 μm. Encapsulation efficiency and loading capacity of microcapsules with fucoxanthin were 98.3% and 0.04%, respectively. Moreover, the fucoxanthin in microcapsules presented higher stability than free fucoxanthin against light, humidity and temperature. Especially, the retention rates of fucoxanthin encapsulated in microcapsules reached 97.20% at 4°C, 92.60% at 25°C, 92.32% with the relative humidity of 33% and 92.60% in the dark. The cumulative amount of fucoxanthin released from microcapsules was 22.92% in simulated gastric fluid (SGF) and 56.55% in simulated intestinal fluid (SIF).

  4. Microcapsules: Reverse Sonoporation and Long-lasting, Safe Contrast

    NASA Astrophysics Data System (ADS)

    Wrenn, Steven; Dicker, Stephen; Small, Eleanor; Maghnouj, Abdelouahid; Hahn, Stephan A.; Mleczko, Michał; Hensel, Karin; Schmitz, Georg

    We present a novel vehicle designed to serve the dual roles of enhanced ultrasound contrast and ultrasound-triggered drug delivery. The vehicle is comprised of a microcapsule that is filled with water in whose aqueous core a population of freely floating, phospholipid-coated microbubbles is suspended. At ultrasound intensities below the inertial cavitation threshold of the microbubbles, the microbubbles provide enhanced ultrasound contrast. The measured contrast is comparable in strength with SonoVue®. Encapsulation of microbubbles within microcapsules putatively eliminates - or at least significantly slows - dissolution of gas in the bulk aqueous medium, thereby avoiding disappearance of microbubbles that would otherwise occur due to pressure-induced gas diffusion across the surfactant monolayer coating the microbubble-water interface. Results suggest that our vehicle might provide longer lasting contrast in a clinical setting. We demonstrate that encapsulation of the microbubbles within microcapsules causes at least a doubling of the ultrasound intensity necessary to induce inertial cavitation. Moreover, no cell death was observed when cells were insonified in the presence of microbubble-containing microcapsules, whereas appreciable cell death occurs with unencapsulated microbubbles. These results point toward a potential safety benefit during ultrasound contrast imaging by using encapsulated microbubbles. Studies are underway to investigate the feasibility of ultrasound-triggered release of drug from the microcapsules, owing to inertial- or stable-cavitation, or both. Whereas leakage from polymeric microcapsule shells, such as poly(lactic acid), seemingly requires shell rupture and is exceedingly difficult to achieve, leakage across a lipid bilayer microcapsule shells appears feasible. Leakage across a bilayer shell has the additional benefit that the leakage mechanism can be tuned via phase behavior (liquid-ordered versus liquid-disordered) and cavitation

  5. 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.

  6. Preparation and evaluation of mucoadhesive cefdinir microcapsules.

    PubMed

    Veerareddy, Prabhakar Reddy; Tedla, Swathi; Banda, Srinivas Reddy; Bandari, Suresh; Jukanti, Raju

    2011-04-01

    The mucoadhesive microcapsules were prepared by using various concentrations of three different mucoadhesive polymers, namely, chitosan, Carbopol 934P, and methyl cellulose as wall materials and cefdinir as the core material employing orificeionic gelation method. The prepared microcapsules were characterized by scanning electron microscope (SEM) and Fourier transform infrared spectrometry (FT-IR). The prepared microcapsules were found to be spherical with particle size ranging from 765±20 to 985±10 μm and encapsulation efficiencies in the range of 55%-92%. The formulation containing Carbopol 934P as mucoadhesive polymer was found to be best with particle size 946±10 μm. The ex vivo wash-off test showed that the mucoadhesion after 1 h was 80% and the in vitro drug release was extended for more than 12 h. FT-IR spectra indicate that there was no interaction between drug and the polymers used in the formulation. Cefdinir is better absorbed from the upper part of the gastrointestinal tract, it suffers from low oral bioavailability (20-30%), shorter biological half-life (1-2 h), and less transit time. Thus, it can be concluded that microcapsules prepared using Carbopol 934P have promising properties for use as mucoadhesive carrier to increase the residence time of cefdinir.

  7. Preparation and evaluation of mucoadhesive cefdinir microcapsules

    PubMed Central

    Veerareddy, Prabhakar Reddy; Tedla, Swathi; Banda, Srinivas Reddy; Bandari, Suresh; Jukanti, Raju

    2011-01-01

    The mucoadhesive microcapsules were prepared by using various concentrations of three different mucoadhesive polymers, namely, chitosan, Carbopol 934P, and methyl cellulose as wall materials and cefdinir as the core material employing orificeionic gelation method. The prepared microcapsules were characterized by scanning electron microscope (SEM) and Fourier transform infrared spectrometry (FT-IR). The prepared microcapsules were found to be spherical with particle size ranging from 765±20 to 985±10 μm and encapsulation efficiencies in the range of 55%–92%. The formulation containing Carbopol 934P as mucoadhesive polymer was found to be best with particle size 946±10 μm. The ex vivo wash-off test showed that the mucoadhesion after 1 h was 80% and the in vitro drug release was extended for more than 12 h. FT-IR spectra indicate that there was no interaction between drug and the polymers used in the formulation. Cefdinir is better absorbed from the upper part of the gastrointestinal tract, it suffers from low oral bioavailability (20–30%), shorter biological half-life (1–2 h), and less transit time. Thus, it can be concluded that microcapsules prepared using Carbopol 934P have promising properties for use as mucoadhesive carrier to increase the residence time of cefdinir. PMID:22171303

  8. Layer-by-layer microcapsules templated on erythrocyte ghost carriers.

    PubMed

    Shaillender, Mutukumaraswamy; Luo, Rongcong; Venkatraman, Subbu S; Neu, Björn

    2011-08-30

    This work reports the fabrication of layer-by-layer (LbL) microcapsules that provide a simple mean for controlling the burst and subsequent release of bioactive agents. Red blood cell (RBC) ghosts were loaded with fluorescently labeled dextran and lysozyme as model compounds via hypotonic dialysis with an encapsulation efficiency of 27-31%. It is demonstrated that these vesicles maintain their shape and integrity and that a uniform distribution of the encapsulated agents within these carriers is achieved. The loaded vesicles were then successfully coated with the biocompatible polyelectrolytes, poly-L-arginine hydrochloride and dextran sulfate. It is demonstrated that the release profiles of the encapsulated molecules can be regulated over a wide range by adjusting the number of polyelectrolyte layers. In addition, the LbL shell also protects the RBC ghost from decomposition thereby potentially preserving the bioactivity of encapsulated drugs or proteins. These microcapsules, consisting of an RBC ghost coated with a polyelectrolyte multilayer, provide a simple mean for the preparation of loaded LbL microcapsules eliminating the core dissolution and post-loading of bioactive agents, which are required for conventional LbL microcapsules.

  9. Adhesive polydopamine coated avermectin microcapsules for prolonging foliar pesticide retention.

    PubMed

    Jia, Xin; Sheng, Wen-bo; Li, Wei; Tong, Yan-bin; Liu, Zhi-yong; Zhou, Feng

    2014-11-26

    In this work, we report a conceptual strategy for prolonging foliar pesticide retention by using an adhesive polydopamine (PDA) microcapsule to encapsulate avermectin, thereby minimizing its volatilization and improving its residence time on crop surfaces. Polydopamine coated avermectin (Av@PDA) microcapsules were prepared by emulsion interfacial-polymerization and characterized by Fourier transform infrared spectroscopy, energy dispersive X-ray spectroscopy, field-emission scanning electron microscope, and transmission electron microscopy. The in situ synthesis route confers Av@PDA microcapsules with remarkable avermectin loading ability of up to 66.5% (w/w). Kinetic study of avermectin release demonstrated that Av@PDA microcapsules exhibit sustained- and controlled-release properties. The adhesive property of Av@PDA microcapsules on different surfaces was verified by a comparative study between Av@PDA and passivated Av@SiO2 and Av@PDA@SiO2 capsules with silica shell. Moreover, PDA shell could effectively shield UV irradiation and so protect avermectin from photodegradation, making it more applicable for foliar spraying. Meanwhile, it is determinated that Av@PDA microcapsules have good mechanical stability property.

  10. Development of Encapsulated Dye for Surface Impact Damage Indicator System.

    DTIC Science & Technology

    1987-09-01

    GROUP SUB-GROUP Composites Ultrasonics Dye Impact Microcapsules 11 04 NDE polyurethane 11 1 0Encapsulation Paint 19. ABSTRACT (Continue on reverse if...encapsulation, microencapsule incorporation into the USAF polyurethane paint, dnd initial correlation study of impact damage to impact coating indication. It is...project were to: 1. Refine the microcapsule formulation to be compatible with MIL-C-83286 paint. 2. Fabricate composite panels from isotropic graphite

  11. 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.

  12. Multifunctional Composite Microcapsules for Oral Delivery of Insulin

    PubMed Central

    Sun, Shaoping; Liang, Na; Gong, Xianfeng; An, Weiwei; Kawashima, Yoshiaki; Cui, Fude; Yan, Pengfei

    2016-01-01

    In this study, we designed and developed a new drug delivery system of multifunctional composite microcapsules for oral administration of insulin. Firstly, in order to enhance the encapsulation efficiency, insulin was complexed with functional sodium deoxycholate to form insulin-sodium deoxycholate complex using hydrophobic ion pairing method. Then the complex was encapsulated into poly(lactide-co-glycolide) (PLGA) nanoparticles by emulsion solvent diffusion method. The PLGA nanoparticles have a mean size of 168 nm and a zeta potential of −29.2 mV. The encapsulation efficiency was increased to 94.2% for the complex. In order to deliver insulin to specific gastrointestinal regions and reduce the burst release of insulin from PLGA nanoparticles, hence enhancing the bioavailability of insulin, enteric targeting multifunctional composite microcapsules were further prepared by encapsulating PLGA nanoparticles into pH-sensitive hydroxypropyl methyl cellulose phthalate (HP55) using organic spray-drying method. A pH-dependent insulin release profile was observed for this drug delivery system in vitro. All these strategies help to enhance the encapsulation efficiency, control the drug release, and protect insulin from degradation. In diabetic fasted rats, administration of the composite microcapsules produced a great enhancement in the relative bioavailability, which illustrated that this formulation was an effective candidate for oral insulin delivery. PMID:28036045

  13. Robust, double-walled microcapsules for self-healing polymeric materials.

    PubMed

    Caruso, Mary M; Blaiszik, Benjamin J; Jin, Henghua; Schelkopf, Stuart R; Stradley, Dylan S; Sottos, Nancy R; White, Scott R; Moore, Jeffrey S

    2010-04-01

    Double-walled polyurethane/poly(urea-formaldehyde) microcapsules (PU/UF) are prepared for use in self-healing materials. This modified encapsulation procedure combines two chemistries to form more robust capsule shell walls in a single operation. Robust capsules are formed by this procedure as long as the aromatic polyisocyanate prepolymer is soluble in the core liquid and the core liquid is compatible with isocyanates. Compared to a standard UF encapsulation, the modified procedure results in capsules with an increase in shell wall thickness from 200 to 675 nm as a function of the amount of PU added to the core liquid. Thermal stability of PU/UF microcapsules prepared with varying amounts of PU is compared to UF microcapsules. Mechanical properties of the PU/UF microcapsules are assessed from single-capsule compression testing.

  14. Incorporating mobile nanospheres in the lumen of hybrid microcapsules for enhanced enzymatic activity.

    PubMed

    Shi, Jiafu; Zhang, Xiaoman; Zhang, Shaohua; Wang, Xiaoli; Jiang, Zhongyi

    2013-11-13

    Physical encapsulation of enzymes in microcapsules, as a mild, controllable method, has been widely utilized for enzyme immobilization. However, this method often suffers from the big mass transfer resistance from the capsule lumen. In this study, a novel biocatalysis system with enhanced catalytic activity is constructed through coencapsulating enzymes and nanospheres in the lumen of protamine/silica hybrid microcapsules, which are synthesized through the synergy of biomimetic silicification and layer-by-layer (LbL) assembly. When utilized as the host for catalase (CAT) encapsulation, the hybrid microcapsules maintain high mechanical stability, high enzyme loading, and low enzyme leaching. Particularly, because of the existence of mobile nanospheres, the mass transfer resistance in the microcapsules is significantly reduced because of the vigorous agitation, thus acquiring an enhanced catalytic activity. Our strategy may also find applications in drug delivery and biosensor fields.

  15. 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.

  16. Dextran coatings for aggregation control of layer-by-layer assembled polyelectrolyte microcapsules.

    PubMed

    Usov, Denys; Sukhorukov, Gleb B

    2010-08-03

    We propose dextran and dextran polyaldehyde (DPA) coatings for modification of layer-by-layer (LbL) assembled polyelectrolyte microcapsules which provide stability against aggregation in 0.75 M aqueous solutions of mono- and bivalent ions (Na(+), Cl(-), Ca(2+), HPO(4)(2-)). The microcapsules were prepared of three bilayers of poly(4-styrenesulfonate) (PSS) and poly(allylamine) (PAH). Dextran and its derivatives were attached to amino-terminated surface of the microcapsules via three types of chemical bonds of subsequently increasing strength: (1) hydrogen bonds, (2) hydrolyzable covalent cross-links resulting from aldehydes and primary amines coupling, and (3) nonhydrolyzable covalent C-N single bonds of secondary amines. Attachment of the DPA materials via the latter two types of bonds resulted in strengthening the capsules' walls which preserved a fraction of the microcapsules from disintegration upon electrostatic swelling in 0.1 M NaOH. The non-disintegrated fraction of the DPA-coated microcapsules restored their initial size after pH was decreased back to neutral. The microcapsules coated with the original dextran immobilized via hydrogen bonds and the bare microcapsules were fully dissolved under the alkaline conditions. The preserved fraction of the microcapsules was higher for the DPA materials with higher contents of the aldehyde groups and after conversion of the hydrolyzable covalent cross-links to the nonhydrolyzable secondary amines via reduction with NaBH(4). The higher contents of the aldehyde groups and the reduction led to the lower limiting swelling degree of the DPA-coated microcapsules at alkaline pH. The proposed coatings can be used for colloid stabilization of polyelectrolyte microcapsules in aqueous medium, encapsulation of pH-insensitive macromolecules at the postpreparation stage, and pH-triggered release of encapsulated material.

  17. 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.

  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. Functional Microcapsules via Thiol-Ene Photopolymerization in Droplet-Based Microfluidics.

    PubMed

    Amato, Douglas V; Lee, Hyomin; Werner, Jörg G; Weitz, David A; Patton, Derek L

    2017-02-01

    Thiol-ene chemistry was exploited in droplet-based microfluidics to fabricate advanced microcapsules with tunable encapsulation, degradation, and thermal properties. In addition, by utilizing the thiol-ene photopolymerization with tunable cross-link density, we demonstrate the importance of monomer conversion on the retention of omniphilic cargo in double emulsion templated microcapsules. Furthermore, we highlight the rapid cure kinetics afforded by thiol-ene chemistry in a continuous flow photopatterning device for hemispherical microparticle production.

  20. 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.

  1. Preparation of polyelectrolyte microcapsules with silver and gold nanoparticles in a shell and the remote destruction of microcapsules under laser irradiation

    NASA Astrophysics Data System (ADS)

    Bukreeva, T. V.; Parakhonsky, B. V.; Skirtach, A. G.; Susha, A. S.; Sukhorukov, G. B.

    2006-10-01

    A number of methods are proposed for encapsulating silver and gold nanoparticles into shells of polyelectrolyte microcapsules for the purpose of increasing the sensitivity of microcapsules to laser radiation. It is shown that capsules with nanocomposite shells can be remotely damaged under laser radiation with different powers and wavelengths. The sensitivity of capsules with silver and gold nanoparticles in shells to this radiation can be controlled by varying the conditions used for the preparation of the capsules. The release of the encapsulated material under laser radiation makes these systems promising for use as microcontainers intended for the target delivery of drugs in an organism.

  2. 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.

  3. 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.

  4. Performance evaluation soil samples utilizing encapsulation technology

    SciTech Connect

    Dahlgran, James R.

    1997-12-01

    Performance evaluation soil samples and method of their preparation are described 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.

  5. [Preparation of polyelectrolyte microcapsules containing ferrosoferric oxide nanoparticles].

    PubMed

    Liu, Xiao-Qing; Zheng, Chun-Li; Zhu, Jia-Bi

    2011-01-01

    In this study, polyelectrolyte microcapsules have been fabricated by biocompatible ferrosoferric oxide nanoparticles (Fe3O4 NPs) and poly allyamine hydrochloride (PAH) using layer by layer assembly technique. The Fe3O4 NPs were prepared by chemical co-precipitation, and characterized by transmission electron microscopy (TEM) and infrared spectrum (IR). Quartz cell also was used as a substrate for building multilayer films to evaluate the capability of forming planar film. The result showed that Fe3O4 NPs were selectively deposited on the surface of quartz cell. Microcapsules containing Fe3O4 NPs were fabricated by Fe3O4 NPs and PAH alternately self-assembly on calcium carbonate microparticles firstly, then 0.2 molL(-1) EDTA was used to remove the calcium carbonate. Scanning electron microscopy (SEM), Zetasizer and vibrating sample magnetometer (VSM) were used to characterize the microcapsule's morphology, size and magnetic properties. The result revealed that Fe3O4 NPs and PAH were successfully deposited on the surface of CaCO3 microparticles, the microcapsule manifested superparamagnetism, size and saturation magnetization were 4.9 +/- 1.2 microm and 8.94 emu x g(-1), respectively. As a model drug, Rhodamin B isothiocyanate labeled bovine serum albumin (RBITC-BSA) was encapsulated in microcapsule depended on pH sensitive of the microcapsule film. When pH 5.0, drug add in was 2 mg, the encapsulation efficiency was (86.08 +/- 3.36) % and the drug loading was 8.01 +/- 0.30 mg x m(L-1).

  6. Probing and repairing damaged surfaces with nanoparticle-containing microcapsules

    NASA Astrophysics Data System (ADS)

    Kratz, Katrina; Narasimhan, Amrit; Tangirala, Ravisubhash; Moon, Sungcheal; Revanur, Ravindra; Kundu, Santanu; Kim, Hyun Suk; Crosby, Alfred J.; Russell, Thomas P.; Emrick, Todd; Kolmakov, German; Balazs, Anna C.

    2012-02-01

    Nanoparticles have useful properties, but it is often important that they only start working after they are placed in a desired location. The encapsulation of nanoparticles allows their function to be preserved until they are released at a specific time or location, and this has been exploited in the development of self-healing materials and in applications such as drug delivery. Encapsulation has also been used to stabilize and control the release of substances, including flavours, fragrances and pesticides. We recently proposed a new technique for the repair of surfaces called `repair-and-go'. In this approach, a flexible microcapsule filled with a solution of nanoparticles rolls across a surface that has been damaged, stopping to repair any defects it encounters by releasing nanoparticles into them, then moving on to the next defect. Here, we experimentally demonstrate the repair-and-go approach using droplets of oil that are stabilized with a polymer surfactant and contain CdSe nanoparticles. We show that these microcapsules can find the cracks on a surface and selectively deliver the nanoparticle contents into the crack, before moving on to find the next crack. Although the microcapsules are too large to enter the cracks, their flexible walls allow them to probe and adhere temporarily to the interior of the cracks. The release of nanoparticles is made possible by the thin microcapsule wall (comparable to the diameter of the nanoparticles) and by the favourable (hydrophobic-hydrophobic) interactions between the nanoparticle and the cracked surface.

  7. Preparation of microcapsules with self-microemulsifying core by a vibrating nozzle method.

    PubMed

    Homar, Miha; Suligoj, Dasa; Gasperlin, Mirjana

    2007-02-01

    Incorporation of drugs in self-microemulsifying systems (SMES) offers several advantages for their delivery, the main one being faster drug dissolution and absorption. Formulation of SMES in solid dosage forms can be difficult and, to date, most SMES are applied in liquid dosage form or soft gelatin capsules. This study has explored the incorporation of SMES in microcapsules, which could then be used for formulation of solid dosage forms. An Inotech IE-50 R encapsulator equipped with a concentric nozzle was used to produce alginate microcapsules with a self-microemulsifying core. Retention of the core phase was improved by optimization of encapsulator parameters and modification of the shell forming phase and hardening solution. The mean encapsulation efficiency of final batches was more than 87%, which resulted in 0.07% drug loading. It was demonstrated that production of microcapsules with a self-microemulsifying core is possible and that the process is stable and reproducible.

  8. 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.

  9. 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

    2016-10-05

    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.

  10. ENCAPSULATED AEROSOLS

    DTIC Science & Technology

    materials determine the range of applicability of each method. A useful microencapsulation method, based on coagulation by inertial force was developed...The generation apparatus, consisting of two aerosol generators in series, was utilized to produce many kinds of microcapsules . A fluid energy mill...was found useful for the production of some microcapsules . The permeability of microcapsule films and the effect of exposure time and humidity were

  11. 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.

  12. 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.

  13. 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. Copyright © 2016 Elsevier B.V. All rights reserved.

  14. 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.

  15. Mechanically enhanced microcapsules for cellular gene therapy.

    PubMed

    Shen, F; Mazumder, M A J; Burke, N A D; Stöver, H D H; Potter, M A

    2009-07-01

    Microcapsules bearing a covalently cross-linked coating have been developed for cellular gene therapy as an improvement on alginate-poly(L-lysine)-alginate (APA) microcapsules that only have ionic cross-linking. In this study, two mutually reactive polyelectrolytes, a polycation (designated C70), poly([2-(methacryloyloxy)ethyl]trimethylammonium chloride-co-2-aminoethyl methacrylate hydrochloride) and a polyanion (designated A70), poly(sodium methacrylate-co-2-(methacryloyloxy)ethyl acetoacetate), were used during the microcapsule fabrication. Ca-alginate beads were sequentially laminated with C70, A70, poly(L-lysine) (PLL), and alginate. The A70 reacts with both C70 and PLL to form a approximately 30 microm thick covalently cross-linked interpenetrating polymer network on the surface of the capsules. Confocal images confirmed the location of the C70/A70/PLL network and the stability of the network after 4 weeks implantation in mice. The mechanical and chemical resistance of the capsules was tested with a "stress test" where microcapsules were gently shaken in 0.003% EDTA for 15 min. APA capsules disappeared during this treatment, whereas the modified capsules, even those that had been retrieved from mice after 4-weeks implantation, remained intact. Analysis of solutions passing through model flat membranes showed that the molecular weight cut-off of alginate-C70-A70-PLL-alginate is similar to that of alginate-PLL-alginate. Recombinant cells encapsulated in APA and modified capsules were able to secrete luciferase into culture media. The modified capsules were found to capture some components of regular culture media used during preparation, causing an immune reaction in implanted mice, but use of UltraCulture serum-free medium was found to prevent this immune reaction. In vivo biocompatibility of the new capsules was similar to the APA capsules, with no sign of clinical toxicity on complete blood counts and liver function tests. The increased stability of the

  16. Chitosan-alginate microcapsules of amoxicillin for gastric stability and mucoadhesion.

    PubMed

    Arora, Saahil; Budhiraja, R D

    2012-01-01

    Amoxicillin-loaded microcapsules were prepared by ionotropic gelation of sodium alginate (ALG) with chitosan (CS) in presence of calcium chloride as gastroretentive delivery system. The effect of pH, concentration of ALG, CS and calcium chloride, and drug : ALG ratio were optimized in this study for minimizing the degradation of drug in acidic environment and increasing the loading efficacy and mucoadhesive efficiency of microcapsules. The optimum condition for prepared CS-ALG microcapsules was 2%w/v ALG, 0.75%w/v CS (pH5.0), and 1.0% w/v calcium chloride. The resulting microcapsules had drug entrapment efficiency of 84% and average size of 840 mm. CS concentration significantly influenced particle size and encapsulation efficiency of CS-ALG microcapsules (P<0.05). Decrease in the drug: ALG ratio resulted in an increased release of amoxicillin in acidic media. The relative decomposition of drug after encapsulation in CS-ALG microcapsules was decreased to 20.7%, 41.9%, and 83.3% in 2, 4, and 8 hours, respectively.

  17. Chitosan-alginate microcapsules of amoxicillin for gastric stability and mucoadhesion

    PubMed Central

    Arora, Saahil; Budhiraja, R. D.

    2012-01-01

    Amoxicillin-loaded microcapsules were prepared by ionotropic gelation of sodium alginate (ALG) with chitosan (CS) in presence of calcium chloride as gastroretentive delivery system. The effect of pH, concentration of ALG, CS and calcium chloride, and drug : ALG ratio were optimized in this study for minimizing the degradation of drug in acidic environment and increasing the loading efficacy and mucoadhesive efficiency of microcapsules. The optimum condition for prepared CS-ALG microcapsules was 2%w/v ALG, 0.75%w/v CS (pH5.0), and 1.0% w/v calcium chloride. The resulting microcapsules had drug entrapment efficiency of 84% and average size of 840 mm. CS concentration significantly influenced particle size and encapsulation efficiency of CS–ALG microcapsules (P<0.05). Decrease in the drug: ALG ratio resulted in an increased release of amoxicillin in acidic media. The relative decomposition of drug after encapsulation in CS-ALG microcapsules was decreased to 20.7%, 41.9%, and 83.3% in 2, 4, and 8 hours, respectively. PMID:22470897

  18. The stability and degradation kinetics of Sulforaphene in microcapsules based on several biopolymers via spray drying.

    PubMed

    Tian, Guifang; Li, Yuan; Yuan, Qipeng; Cheng, Li; Kuang, Pengqun; Tang, Pingwah

    2015-05-20

    Sulforaphene (SFE) was extracted from the radish seeds and the purity of SFE extracted by our laboratory was 95%. It is well known that SFE can prevent cancers. It is also known that SFE is unstable to heat. To overcome the problem, SFE microcapsules using natural biopolymers were prepared by spray drying. The results indicated that SFE microcapsules using hydroxypropyl-β-cyclodextrin (HP-β-CD), maltodextrin (MD) and isolated soybean protein (SPI) as wall materials could effectively improve its stability against heat, especially SFE-loaded HP-β-CD and MD microcapsules. The amount of SFE in the microcapsules was found 20% higher than that of the non-encapsulated SFE under 90 °C in 168 h. Our finding suggested that the rate of degradation of the non-encapsulated and encapsulated SFE with HP-β-CD, MD and SPI followed the first-order kinetics. The speed of the degradation of the encapsulated SFE in biopolymers increased from SFE with HP-β-CD, to SFE with MD, and to SFE-SPI. The non-encapsulated SFE degrades fastest. Copyright © 2015 Elsevier Ltd. All rights reserved.

  19. 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.

  20. In-vitro analysis of APA microcapsules for oral delivery of live bacterial cells.

    PubMed

    Chen, H; Ouyang, W; Jones, M; Haque, T; Lawuyi, B; Prakash, S

    2005-08-01

    Oral administration of microcapsules containing live bacterial cells has potential as an alternative therapy for several diseases. This article evaluates the suitability of the alginate-poly-L-lysine-alginate (APA) microcapsules for oral delivery of live bacterial cells, in-vitro, using a dynamic simulated human gastro-intestinal (GI) model. Results showed that the APA microcapsules were morphologically stable in the simulated stomach conditions, but did not retain their structural integrity after a 3-day exposure in simulated human GI media. The microbial populations of the tested bacterial cells and the activities of the tested enzymes in the simulated human GI suspension were not substantially altered by the presence of the APA microcapsules, suggesting that there were no significant adverse effects of oral administration of the APA microcapsules on the flora of the human gastrointestinal tract. When the APA microcapsules containing Lactobacillus plantarum 80 (LP80) were challenged in the simulated gastric medium (pH = 2.0), 80.0% of the encapsulated cells remained viable after a 5-min incubation; however, the viability decreased considerably (8.3%) after 15 min and dropped to 2.6% after 30 min and lower than 0.2% after 60 min, indicating the limitations of the currently obtainable APA membrane for oral delivery of live bacteria. Further in-vivo studies are required before conclusions can be made concerning the inadequacy of APA microcapsules for oral delivery of live bacterial cells.

  1. 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

    2015-08-05

    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.

  2. 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.

  3. Hybrid lipid-silica microcapsules engineered by phase coacervation of Pickering emulsions to enhance lipid hydrolysis.

    PubMed

    Simovic, Spomenka; Heard, Peter; Prestidge, Clive A

    2010-07-14

    We report on the fabrication of dry hybrid lipid-silica microcapsules for enhanced lipid hydrolysis using Pickering emulsion templates formed by interfacial nanoparticle-emulsifier electrostatic interaction. The microcapsules are produced by controlled precipitation of emulsion droplets by oppositely charged silica nanoparticles at room temperature. Microcapsule formation is driven by the interfacial structure of the initial Pickering emulsion, which is in turn controlled by the nanoparticle to lipid ratio. In the region of charge reversed, precipitated and aggregated droplets, droplet-nanoparticle networks have been identified by freeze-fracture SEM imaging. The microcapsules have diameters in the range 20-50 mum and contain approximately 65% oil distributed within an internal matrix structure composed of a labyrinth of interconnected pores approximately 20-100 nm. Pore distribution and diameters depend on the silica to nanoparticle ratio that in turn determines droplet coating and stability. The microcapsules facilitate enhanced lipid hydrolysis kinetics, i.e. their pseudo first-order rate constant for lipid hydrolysis is approximately 3 times greater than for equivalent submicron lipid droplets. This behaviour is attributed to the increased oil surface area within the microcapsule due to the specific porous structure that causes rapid release of submicron and micron size oil droplets. The simple route for fabrication of porous microcapsule morphologies may present new opportunities for applications in encapsulation, delivery, coatings, and catalysis.

  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. Dye diffusion from microcapsules with different shell thickness into mammalian skin.

    PubMed

    Yow, Huai Nyin; Wu, Xiao; Routh, Alexander F; Guy, Richard H

    2009-05-01

    Oil-in-water microcapsules with varying shell thicknesses were fabricated via a coacervation technique, whereby evaporation of volatile solvents induced the shell-forming polymer to precipitate, phase separate and migrate to the oil/water interface to form microcapsules. These microcapsules encapsulated a lipophilic dye within their cores and were applied topically onto porcine skin for 6h. Results indicated that the dye preferentially accumulated within the skin furrows and hair follicles, though the dye did not penetrate beyond the stratum corneum. A model estimates the diffusion coefficients of dye through the microcapsule shell and within the skin to be approximately 10(-18) and 10(-16)m(2)s(-1), respectively.

  6. High-Throughput Platform for Synthesis of Melamine-Formaldehyde Microcapsules.

    PubMed

    Çakir, Seda; Bauters, Erwin; Rivero, Guadalupe; Parasote, Tom; Paul, Johan; Du Prez, Filip E

    2017-07-10

    The synthesis of microcapsules via in situ polymerization is a labor-intensive and time-consuming process, where many composition and process factors affect the microcapsule formation and its morphology. Herein, we report a novel combinatorial technique for the preparation of melamine-formaldehyde microcapsules, using a custom-made and automated high-throughput platform (HTP). After performing validation experiments for ensuring the accuracy and reproducibility of the novel platform, a design of experiment study was performed. The influence of different encapsulation parameters was investigated, such as the effect of the surfactant, surfactant type, surfactant concentration and core/shell ratio. As a result, this HTP-platform is suitable to be used for the synthesis of different types of microcapsules in an automated and controlled way, allowing the screening of different reaction parameters in a shorter time compared to the manual synthetic techniques.

  7. 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. © 2016 Institute of Food Technologists®

  8. 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.

  9. Effect of Variation in Viscosity Grade of Ethycellulose on Theophylline Microcapsule Properties Prepared by Emulsion Solvent Evaporation.

    PubMed

    Garekani, Hadi Afrasiabi; Ahmadi, Behzad; Sadeghi, Fatemeh

    2017-01-01

    There are conflicting reports regarding the effect of polymer viscosity grade on microcapsule properties. The aim of the present study was to investigate the effect of just viscosity grade of ethylcellulose (EC) (not polymeric solution) on properties of theophylline microcapsules prepared by emulsion solvent evaporation. The effect of EC viscosity grade and drug:polymer ratio was investigated on microcapsule properties (yield, particle size, morphology, surface characteristics and drug release). Differential scanning calorimetry (DSC) and X-ray powder diffraction (XRD) were implemented to study the interaction and solid state of drug. The microcapsules were compressed in the presence of excipients and drug release was evaluated. The yield of microencapsulation and encapsulation efficiency at 1:1 drug:polymer ratio was dependent on EC viscosity. Microcapsules were spherical with some pores on their surfaces. The number of pores was more and their size was bigger for EC 100 cP microcapsules. Theophylline remained in crystalline form after encapsulation. DSC studies confirmed lack of interaction between drug and polymer. The drug release was rapid at 2:1 drug:polymer whilst it was slowed down at 1:1 drug:polymer ratio. Microcapsules obtained from EC 100 cP showed slightly faster drug release at latter ratio. Marginal changes in release rate were observed after compression of microcapsules. All viscosity grades of EC were able to sustain the release of the drug from microcapsules. Considering the similar release profiles for microcapsules prepared from different viscosities of EC, the use of lower viscosity grade of EC is recommended due to the ease of production and also less processing time. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

  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. Low-Ceiling-Temperature Polymer Microcapsules with Hydrophobic Payloads via Rapid Emulsion-Solvent Evaporation.

    PubMed

    Tang, Shijia; Yourdkhani, Mostafa; Possanza Casey, Catherine M; Sottos, Nancy R; White, Scott R; Moore, Jeffrey S

    2017-06-14

    We report a microencapsulation procedure based on rapid solvent evaporation to prepare microcapsules with hydrophobic core materials and low-ceiling-temperature polymer shell wall of cyclic poly(phthalaldehyde) (cPPA). We use and compare microfluidic and bulk emulsions. In both methods, rapid solvent evaporation following emulsification resulted in kinetically trapped core-shell microcapsules, whereas slow evaporation resulted in acorn morphology. Through the systematic variation of encapsulation parameters, we found that polymer-to-core weight ratios higher than 1 and polymer concentrations higher than 4.5 wt % in the oil phase were required to obtain a core-shell structure. This microencapsulation procedure enabled the fabrication of microcapsules with high core loading, controlled size, morphology, and stability. This procedure is versatile, allowing for the encapsulation of other hydrophobic core materials, i.e., mineral oil and organotin catalyst, or using an alternative low-ceiling-temperature polymer shell wall, poly(vinyl tert-butyl carbonate sulfone).

  12. 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

  13. [Encapsulating hepatocytes with chitosan in physiological conditions].

    PubMed

    Zhu, Jianhang; Zhang, Bao; Yan, Xiluan; Lao, Xuejun; Yu, Hanry

    2006-10-01

    Prepared from 15.3% N-acetylated chitosan (FNC), half N-acetylated chitosan (HNC) possesses a good solubility in a weak basic solution, guaranteeing the formation of microcapsules by the coacervating reaction between HNC and methacrylic acid (MAA)-hydroxyethyl methacrylate (HEMA)-methyl methacrylate (MMA) (MAA-HEMA-MMA) terpolymer under physiological conditions. When hepatocytes were encapsulated in such 3-dimensional microenvironment, as compared to monolayer culture, cell functions, including P450 activity, urea production and albumin release, were well supported. The prepared microcapsules have good mechanical stability and permeability.

  14. 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

  15. Preparation of monodisperse controlled release microcapsules.

    PubMed

    Brandau, Thorsten

    2002-08-21

    Since the handling of many active agents in its pure form has many problems, microencapsulation is used to have better properties in the product. With the patented BRACE-Processes it is possible to encapsulate a very wide range of materials in monodisperse Microspheres or Microcapsules in a diameter range of 50-6000 microm with a very narrow size distribution. The Microsphere Units from BRACE can be customer tailored to the materials and all necessary specifications as FDA, GMP/GLP, EX, CIP, WIP etc. The throughput of the BRACE Microsphere Units ranges between 10 ml per h (small laboratory scale) up to over 1000 l per h (production scale) while the production cost are very low, especially if compared directly to competitive processes as spray-drying or fluidized bed coating.

  16. Chitosan-Alginate Microcapsules Provide Gastric Protection and Intestinal Release of ICAM-1-Targeting Nanocarriers, Enabling GI Targeting In Vivo.

    PubMed

    Ghaffarian, Rasa; Herrero, Edgar Pérez; Oh, Hyuntaek; Raghavan, Srinivasa R; Muro, Silvia

    2016-05-24

    When administered intravenously, active targeting of drug nanocarriers (NCs) improves biodistribution and endocytosis. Targeting may also improve oral delivery of NCs to treat gastrointestinal (GI) pathologies or for systemic absoption. However, GI instability of targeting moieties compromises this strategy. We explored whether encapsulation of antibody-coated NCs in microcapsules would protect against gastric degradation, providing NCs release and targeting in intestinal conditions. We used nanoparticles coated with antibodies against intercellular adhesion molecule-1 (anti-ICAM) or non-specific IgG. NCs (~160-nm) were encapsulated in ~180-μm microcapsules with an alginate core, in the absence or presence of a chitosan shell. We found >95% NC encapsulation within microcapsules and <10% NC release from microcapsules in storage. There was minimal NC release at gastric pH (<10%) and burst release at intestinal pH (75-85%), slightly attenuated by chitosan. Encapsulated NCs afforded increased protection against degradation (3-4 fold) and increased cell targeting (8-20 fold) after release vs. non-encapsulated NCs. Mouse oral gavage showed that microencapsulation provided 38-65% greater protection of anti-ICAM NCs in the GI tract, 40% lower gastric retention, and 4-9-fold enhanced intestinal biodistribution vs. non-encapsulated NCs. Therefore, microencapsulation of antibody-targeted NCs may enable active targeting strategies to be effective in the context of oral drug delivery.

  17. 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.

  18. 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.

  19. Stability of cardamom (Elettaria cardamomum) essential oil in microcapsules made of whey protein isolate, guar gum, and carrageenan.

    PubMed

    Mehyar, Ghadeer F; Al-Ismail, Khalid M; Al-Isamil, Khalid M; Al-Ghizzawi, Hana'a M; Holley, Richard A

    2014-10-01

    The effects of microencapsulating cardamom essential oil (CEO) in whey protein isolate (WPI) alone and combined with guar gum (GG) and carrageen (CG) on microencapsulation efficiency, oil chemical stability, and microcapsule structure were investigated. Freeze-dried microcapsules were prepared from emulsions containing (w/w): 15% and 30% WPI; 0.1% GG, and 0.2% CG as wall materials with CEO (at 10% of polymer concentration) as core material, and physical properties and chemical stability were compared. Bulk density of microcapsules was highest in WPI without GG or CG and in 30% WPI + GG microcapsules, and was more affected by moisture content (r = -0.6) than by mean particle diameter (d43 ; r = -0.2) and span (r = 0.1). Microcapsules containing only WPI had the highest entrapped oil (7.5%) and microencapsulation efficiency (98.5%). The concentrations of 1,8-cineole and d-limonene were used as indicators for microcapsule chemical stability since they were the main components of CEO. Microcapsules retained higher (P ≤ 0.05) concentrations of both components than non-microencapsulated CEO during 16 wk storage at 20 ºC, but higher loss of both components was noted at 35 ºC. Microencapsulated d-limonene was reduced faster than 1,8-cineole regardless of temperature. The 30% WPI and 30% WPI + GG microcapsules retained CEO best throughout storage at both storage temperatures. Scanning electron micrographs revealed that WPI microcapsules had smooth surfaces, were relatively homogenous and regular in shape, whereas GG and CG addition increased visual surface porosity and reduced shape regularity. It was concluded that the best formulation for encapsulating CEO was 30% WPI. Encapsulating cardamom essential oil in whey protein isolate alone or combined with guar gum produced dried powders that effectively retained and chemically stabilized CEO, and therefore enhanced its handling and storability. © 2014 Institute of Food Technologists®

  20. 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

  1. 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.

  2. Reviewing the use of ethylcellulose, methylcellulose and hypromellose in microencapsulation. Part 3: Applications for microcapsules.

    PubMed

    Rogers, True L; Wallick, Dave

    2012-05-01

    This three-part review has been developed following the evaluation of literature where ethylcellulose, methylcellulose, or hypromellose was used to make microcapsules. Parts 1 and 2 of the review are published in separate papers. Part 1 covers the various materials used to formulate microcapsules, and Part 2 covers the various techniques used to make microcapsules. In the current paper, Part 3 covers the end-use applications for which microcapsules are used. Examples of applications to be covered include modified release, improved efficacy and safety, multiparticulate compression, improved processability and stability, and taste- and odor-masking. It is hoped that formulators can use Part 3 to understand the various end-use applications of microcapsules made from these encapsulating polymers. SciFinder was utilized to perform the literature search. SciFinder leverages literature databases, such as Chemical Abstracts Service Registry and Medline. A total of 379 references were identified during the review. The need for a three-part review reflects the extensive amount of literature identified concerning these three encapsulating polymers.

  3. Effect of spray nozzle design on fish oil-whey protein microcapsule properties.

    PubMed

    Legako, Jerrad; Dunford, Nurhan Turgut

    2010-08-01

    Microencapsulation improves oxidative stability and shelf life of fish oil. Spray and freeze drying are widely used to produce microcapsules. Newer spray-nozzles utilize multiple fluid channels allowing for mixing of wall and core materials at the point of atomization. Sonic energy has also been employed as a means of atomization. The objective of this study was to examine the effect of nozzle type and design on fish oil encapsulation efficiency and microcapsule properties. A total of 3 nozzle types, a pressure nozzle with 1 liquid channel, a pressure nozzle with 2 liquid channels, and a sonic atomizer with 2 liquid channels were examined for their suitability to encapsulate fish oil in whey protein isolate. Physical and chemical properties of freeze dried microcapsules were compared to those of microcapsules produced by spray drying. The 2-fluid pressure and ultrasonic nozzles had the highest (91.6%) and the lowest microencapsulation efficiencies (76%), respectively. There was no significant difference in bulk density of microcapsules produced by ultrasonic and 3-fluid pressure nozzles. The ultrasonic nozzle showed a significantly narrower particle size distribution than the other nozzles. This study demonstrated that new nozzle designs that eliminate emulsion preparation prior to spray drying can be beneficial for microencapsulation applications. However, there is still a need for research to improve microencapsulation efficiency of multiple channel spray nozzles. Practical Application: Since this research evaluates new spray nozzle designs for oil microencapsulation, the information presented in this article could be an interest to fish oil producers and food industry.

  4. Facile Method To Prepare Microcapsules Inspired by Polyphenol Chemistry for Efficient Enzyme Immobilization.

    PubMed

    Zhang, Shaohua; Jiang, Zhongyi; Wang, Xiaoli; Yang, Chen; Shi, Jiafu

    2015-09-09

    In this study, a method inspired by polyphenol chemistry is developed for the facile preparation of microcapsules under mild conditions. Specifically, the preparation process includes four steps: formation of the sacrificial template, generation of the polyphenol coating on the template surface, cross-linking of the polyphenol coating by cationic polymers, and removal of the template. Tannic acid (TA) is chosen as a representative polyphenol coating precursor for the preparation of microcapsules. The strong interfacial affinity of TA contributes to the formation of polyphenol coating through oxidative oligomerization, while the high reactivity of TA is in charge of reacting/cross-linking with cationic polymer polyethylenimine (PEI) through Schiff base/Michael addition reaction. The chemical/topological structures of the resultant microcapsules are simultaneously characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier Transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), etc. The wall thickness of the microcapsules could be tailored from 257±20 nm to 486±46 nm through changing the TA concentration. The microcapsules are then utilized for encapsulating glucose oxidase (GOD), and the immobilized enzyme exhibits desired catalytic activity and enhanced pH and thermal stabilities. Owing to the structural diversity and functional versatility of polyphenols, this study may offer a facile and generic method to prepare microcapsules and other kinds of functional porous materials.

  5. Pyrene biodegradation with layer-by-layer assembly bio-microcapsules.

    PubMed

    Deng, Fucai; Zhang, Zhengfang; Yang, Chen; Guo, Chuling; Lu, Guining; Dang, Zhi

    2017-04-01

    Biotechnology is considered as a promising technology for the removal of polycyclic aromatic hydrocarbons from the environment. Free bacteria are often sensitive to some biotic and abiotic factors in the environment to the extent that their ability to effect biodegradation of organic pollutants, such as polycyclic aromatic hydrocarbons, is hampered. Consequently, it is imperative to carry out investigations into biological systems that will obviate or aid tolerance of bacteria to harsh environmental conditions. Chitosan/alginate bio-microcapsules produced using layer-by-layer (LBL) assembly method were tested for pyrene (PYR) biodegradation under harsh environmental conditions. Morphology observation indicated that the flake bio-microcapsules could be successfully prepared through LBL assembly method. Surface analysis showed that the bio-microcapsules had large fractions of mesopores. The results of the biodegradation experiments revealed that the 95% of 10mgL(-1) PYR could be removed by the bacteria encapsulated chitosan/alginate bio-microcapsules in 3 days, which was higher than that of the free bacteria (59%). Compared to the free cells, the bacteria encapsulated chitosan/alginate bio-microcapsules produced 1-6 times higher PYR biodegradation rates at a high initial PYR concentration (50mgL(-1)) and extremely low pH values (pH =3) or temperatures (10°C or 40°C), as well as high salt stress. The results indicated that bacteria in microcapsules treatment gained a much higher tolerance to environmental stress and LBL bio-microcapsule could be promising candidate for remediating the organic pollutants. Copyright © 2016 Elsevier Inc. All rights reserved.

  6. Microcapsules loaded with the probiotic Lactobacillus paracasei BGP-1 produced by co-extrusion technology using alginate/shellac as wall material: Characterization and evaluation of drying processes.

    PubMed

    Silva, Marluci P; Tulini, Fabricio L; Ribas, Marcela M; Penning, Manfred; Fávaro-Trindade, Carmen S; Poncelet, Denis

    2016-11-01

    Microcapsules containing Lactobacillus paracasei BGP-1 were produced by co-extrusion technology using alginate and alginate-shellac blend as wall materials. Sunflower oil and coconut fat were used as vehicles to incorporate BGP-1 into the microcapsules. The microcapsules were evaluated with regard the particle size, morphology, water activity and survival of probiotics after 60days of storage at room temperature. Fluidized bed and lyophilization were used to dry the microcapsules and the effect of these processes on probiotic viability was also evaluated. Next, dried microcapsules were exposed to simulated gastrointestinal fluids to verify the survival of BGP-1. Microcapsules dried by fluidized bed had spherical shape and robust structures, whereas lyophilized microcapsules had porous and fragile structures. Dried microcapsules presented a medium size of 0.71-0.86mm and aw ranging from 0.14 to 0.36, depending on the drying process. When comparing the effects of drying processes on BGP-1 viability, the fluidized bed was less aggressive than lyophilization. The alginate-shellac blend combined with coconut fat as core effectively protected the encapsulated probiotic under simulated gastrointestinal conditions. Thus, the production of microcapsules by co-extrusion followed by drying using the fluidized bed is a promising strategy for protection of probiotic cells. Copyright © 2016 Elsevier Ltd. All rights reserved.

  7. 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.

  8. Guided Placement of Magnetic Microcapsules in Self-Healing Polymeric Materials

    NASA Astrophysics Data System (ADS)

    Crall, Matthew D.

    Magnetically guided microcapsules are used to achieve self-healing with 1/10th of the healing components required using traditional self-healing approaches. Microcapsules are rendered responsive to magnetic fields by suspending magnetic nanoparticles in the core material. The nanoparticles are surface-modified to enable ureaformaldehyde encapsula tion within a phenyl acetate core. Nanoparticles are characterized via scanning electron microscopy (SEM) and transmission electron microscopy (TEM), showing an average size of 8 nm across the hexagonal cross section. Simple emulsion tests are conducted to qualitatively determine if the nanoparticles are suitable for encapsulation, and contact angle testing is also preformed to determine the effectiveness of the nanoparticle coating. Microcapsules were characterized by both SEM and optical microscopy to determine size distribution, shell wall characteristics, and confirm the presence of nanoparticles in the core. Magnetized razorblades are used to manipulate the nanoparticles within the microcapsule core. Barrier property studies are performed using TGA, and AAS is used to quantify the nanoparticle loading within the microcapsules, found to be within 0.10% of the added concentration of 0.33 wt% nanoparticles suspended in the phenyl acetate core material. Magnetic fields are used to guide the microcapsules to the expected fracture location in tapered double cantilever beam (TDCB) epoxy specimens. This guiding method achieves a ten-fold increase in local microcapsule concentration over controls that are cured without magnets, resulting in self-healing behavior that remains constant for microcapsule concentrations as low as 0.025 wt%. This value is two orders of magnitude lower than the concentration required to achieve consistent self-healing using traditional approaches. Additionally, the observed healing for guided specimens is both more consistent and significantly higher than that of control specimens.

  9. 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. © 2013 American Institute of Chemical Engineers.

  10. Biologic effect and immunoisolating behavior of BMP-2 gene-transfected bone marrow-derived mesenchymal stem cells in APA microcapsules.

    PubMed

    Ding, H F; Liu, R; Li, B G; Lou, J R; Dai, K R; Tang, T T

    2007-11-03

    We investigated the encapsulation of BMP-2 gene-modified mesenchymal stem cells (MSCs) in alginate-poly-L-lysine (APA) microcapsules for the persistent delivery of bone morphogenic protein-2 (BMP-2) to induce bone formation. An electrostatic droplet generator was employed to produce APA microcapsules containing encapsulated beta-gal or BMP-2 gene-transfected bone marrow-derived MSCs. We found that X-gal staining was still positive 28 days after encapsulation. Encapsulated BMP-2 gene-transfected cells were capable of constitutive delivery of BMP-2 proteins for at least 30 days. The encapsulated BMP-2 gene-transfected MSCs or the encapsulated non-gene transfer MSCs (control group) were cocultured with the undifferentiated MSCs. The gene products from the encapsulated BMP-2 cells could induce the undifferentiated MSCs to become osteoblasts that had higher alkaline phosphatase (ALP) activity than those in the control group (p<0.05). The APA microcapsules could inhibit the permeation of fluorescein isothiocyanate-conjuncted immunoglobulin G. Mixed lymphocyte reaction also indicates that the APA microcapsules could prevent the encapsulated BMP-2 gene-transfected MSCs from initiating the cellular immune response. These results demonstrated that the nonautologous BMP-2 gene-transfected stem cells are of potential utility for enhancement of bone repair and bone regeneration in vivo.

  11. Pharmacokinetics and pharmacodynamics of controlled release insulin loaded PLGA microcapsules using dry powder inhaler in diabetic rats.

    PubMed

    Hamishehkar, Hamed; Emami, Jaber; Najafabadi, Abdolhossien Rouholamini; Gilani, Kambiz; Minaiyan, Mohsen; Hassanzadeh, Kambiz; Mahdavi, Hamid; Koohsoltani, Maryam; Nokhodchi, Ali

    2010-03-01

    The pulmonary route is an alternative route of administration for the systemic delivery of peptide and proteins with short-half lives. A long-acting formulation of insulin was prepared by encapsulation of protein into respirable, biodegradable microcapsules prepared by an oil in oil emulsification/solvent evaporation method. Insulin-loaded PLGA microcapsules prepared as a dry powder inhaler formulation were administered via the pulmonary route to diabetic rats and serum insulin and glucose concentrations were monitored. Control treatments consisted of respirable spray-dried insulin (RSDI) powder administered by intratracheal insufflation, insulin-loaded PLGA microcapsules and NPH (long-acting) insulin administered by subcutaneous (SC) administration. Pharmacokinetic analysis demonstrated that insulin administered in PLGA microcapsules illustrated a sustained release profile which resulted in a longer mean residence time, 4 and 5 fold longer than those after pulmonary administration of RSDI and SC injection of NPH insulin, respectively. Accordingly, the hypoglycemic profile followed a stable and sustained pattern which remained constant between 10 and 48 h. Results of the in vitro experiments were in good agreement with those of in vivo studies. Bronchoalveolar lavage fluid analysis indicated that microcapsules administration did not increase the activities of lactate dehydrogenase and total protein. However, histological examination of the lung tissue indicated a minor but detectable effect on the normal physiology of the rat lung. These findings suggest that the encapsulation of peptides and proteins into PLGA microcapsules technique could be a promising controlled delivery system for pulmonary administration.

  12. 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

  13. Controlled-release nanoencapsulating microcapsules to combat inflammatory diseases

    PubMed Central

    Baek, Jong-Suep; Yeo, Eng Wan; Lee, Yin Hao; Tan, Nguan Soon; Loo, Say Chye Joachim

    2017-01-01

    The World Health Organization (WHO) has reported that globally 235 million people suffer from chronic and other inflammatory diseases. The short half-lives of nonsteroidal anti-inflammatory drugs (NSAIDs) and their notoriety in causing gastrointestinal discomforts, warrants these drugs to be released in a controlled and sustained manner. Although polymeric particles have been widely used for drug delivery, there are few reports that showcase their ability in encapsulating and sustaining the release of NSAIDs. In this paper, polymeric nanoencapsulating microcapsules loaded with NSAIDs were fabricated using solid/water/oil/water emulsion solvent evaporation method. Two NSAIDs, ibuprofen and naproxen, were first pre-loaded into nanoparticles and then encapsulated into a larger hollow microcapsule that contained the third NSAID, celecoxib. A high encapsulation efficiency (%) of these NSAIDs was achieved and a sustained release (up to 30 days) of these drugs in phosphate-buffered saline was observed. Then, a gastrointestinal drug – cimetidine (CIM) – was co-loaded with the NSAIDs. This floating delivery system exhibited excellent buoyancy (~88% up to 24 h) in simulated gastric fluid. It also allowed a sequential release of the drugs, whereby an immediate release of CIM followed by NSAIDs was observed. Drug release of the NSAIDs observed Fickian diffusion mechanism, whereas CIM observed non-Fickian diffusion. Therefore, this delivery system is a promising platform to control the delivery of NSAIDs to combat inflammatory diseases, thereby protecting against possible gastrointestinal side effects that may arise from the overuse of NSAIDs. PMID:28652708

  14. Polymeric microcapsules with switchable mechanical properties for self-healing concrete: synthesis, characterisation and proof of concept

    NASA Astrophysics Data System (ADS)

    Kanellopoulos, A.; Giannaros, P.; Palmer, D.; Kerr, A.; Al-Tabbaa, A.

    2017-04-01

    Microcapsules, with sodium silicate solution as core, were produced using complex coacervation in a double, oil-in-water-in oil, emulsion system. The shell material was a gelatin-acacia gum crosslinked coacervate and the produced microcapsules had diameters ranging from 300 to 700 μm. The shell material designed with switchable mechanical properties. When it is hydrated exhibits soft and ‘rubbery’ behaviour and, when dried, transitions to a stiff and ‘glassy’ material. The microcapsules survived drying and rehydrating cycles and preserved their structural integrity when exposed to highly alkaline solutions that mimic the pH environment of concrete. Microscopy revealed that the shell thickness of the microcapsules varies across their perimeter from 5 to 20 μm. Thermal analysis showed that the produced microcapsules were very stable up to 190 °C. Proof of concept investigation has demonstrated that the microcapsules successfully survive and function when exposed to a cement-based matrix. Observations showed that the microcapsules survive mixing with cement and rupture successfully upon crack formation releasing the encapsulated sodium silicate solution.

  15. 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

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

    PubMed

    Lu, Juan; Zhang, Xiaoqian; 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.

  17. IL-1RA gene-transfected bone marrow-derived mesenchymal stem cells in APA microcapsules could alleviate rheumatoid arthritis.

    PubMed

    Hu, Jianhua; Li, Hongjian; Chi, Guanhao; Yang, Zhao; Zhao, Yi; Liu, Wei; Zhang, Chao

    2015-01-01

    In order to investigate the encapsulation of interleukin 1 receptor antagonist (IL-RA) gene-modified mesenchymal stem cells (MSCs) in alginate-poly-L-lysine (APA) microcapsules for the persistent delivery of interleukin 1 receptor antagonist (IL-RA) to treat Rheumatoid arthritis (RA). We transfect mesenchymal stem cells with IL-RA gene, and quantify the IL-RA proteins released from the encapsulated cells followed by microencapsulation of recombinant mesenchymal stem cells, and thus observe the permeability of APA microcapsules and evaluate clinical effects after induction and treatment of collagen-induced arthritis (CIA). The concentration of IL-RA in the supernatant was determined by IL-RA ELISA kit by run in technical triplicates using samples from three separate mice. Encapsulated IL-RA gene-transfected cells were capable of constitutive delivery of IL-RA proteins for at least 30 days. Moreover, the APA microcapsules could inhibit the permeation of fluorescein isothiocyanate-conjuncted immunoglobulin G. Also, it has been found that the APA microcapsules can significantly attenuate collagen induced arthritis after delivering of APA microcapsules to rats. Our results demonstrated that the nonautologous IL-RA gene-transfected stem cells are of potential utility for RA therapy.

  18. Reviewing the use of ethylcellulose, methylcellulose and hypromellose in microencapsulation. Part 1: materials used to formulate microcapsules.

    PubMed

    Rogers, True L; Wallick, Dave

    2012-02-01

    This review highlights references where ethylcellulose, methylcellulose and hypromellose were used to make microcapsules. The review has been divided into three parts. This first part discusses various materials used to formulate microcapsules, such as the three encapsulating polymers as well as protective colloids, plasticizers and surfactants. The second part covers the various techniques used to make microcapsules, such as temperature-induced phase separation, emulsion solvent evaporation, solvent evaporation, film coating, and others. The third part covers the various applications for which microcapsules are used, such as modified release, improved efficacy and safety, taste- and odor-masking, and others. It is hoped that formulators can use Part 1 as a guide to the literature documenting formulation of microcapsules made from these encapsulating polymers. SciFinder was utilized to identify the pertinent literature. SciFinder leverages literature databases, such as Chemical Abstracts Service Registry and Medline. A total of 379 references were identified during the review. The need for a three-part review reflects the extensive amount of literature identified concerning these three encapsulating polymers.

  19. Stiffness-independent highly efficient on-chip extraction of cell-laden hydrogel microcapsules from oil emulsion into aqueous solution by dielectrophoresis

    PubMed Central

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

    2015-01-01

    A dielectrophoresis (DEP)-based method is reported to achieve 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 (IFT) forces with no trapped oil while the encapsulated cells are free from the electrical damages due to the Faraday cage effect. PMID:26297051

  20. Assessment of the Behavior of Mesenchymal Stem Cells Immobilized in Biomimetic Alginate Microcapsules.

    PubMed

    Garate, Ane; Ciriza, Jesús; Casado, Javier G; Blazquez, Rebeca; Pedraz, José Luis; Orive, Gorka; Hernandez, Rosa Maria

    2015-11-02

    The combination of mesenchymal stem cells (MSCs) and biomimetic matrices for cell-based therapies has led to enormous advances, including the field of cell microencapsulation technology. In the present work, we have evaluated the potential of genetically modified MSCs from mice bone marrow, D1-MSCs, immobilized in alginate microcapsules with different RGD (Arg-Gly-Asp) densities. Results demonstrated that the microcapsules represent a suitable platform for D1-MSC encapsulation since cell immobilization into alginate matrices does not affect their main characteristics. The in vitro study showed a higher activity of D1-MSCs when they are immobilized in RGD-modified alginate microcapsules, obtaining the highest therapeutic factor secretion with low and intermediate densities of the bioactive molecule. In addition, the inclusion of RGD increased the differentiation potential of immobilized cells upon specific induction. However, subcutaneous implantation did not induce differentiation of D1-MSCs toward any lineage remaining at an undifferentiated state in vivo.

  1. A microfluidic chip for controlled release of drugs from microcapsules

    PubMed Central

    Cheng, Wen-Chuan; He, Yuan; Chang, An-Yi; Que, Long

    2013-01-01

    A new microfluidic device with liquid-droplet merging and droplet storage functions for the controlled release of drugs from microcapsules is reported. A switching channel is designed and integrated within the microfluidic device, facilitating the generation and capturing of uniform droplets by the storage chambers. The drug model is the MnCO3 microparticle, which is encapsulated by a microcapsule and fabricated using a simple layer-by-layer nanoassembly process. The merging function is used for dynamically adding the control solution into the droplets, which contain drugs within the microcapsules (DWμCs) and water. The storage chambers are used for collecting DWμCs-laden droplets so that the controlled-drug release in specific droplets can be monitored for an extended period of time, which has been experimentally implemented successfully. This technology could offer a promising technical platform for the long-term observation and studies of drug effects on specific cells in a controlled manner, which is especially useful for single cell analysis. PMID:24396536

  2. 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%.

  3. 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

  4. 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.

  5. Sustained Dye Release Using Poly(urea-urethane)/Cellulose Nanocrystal Composite Microcapsules.

    PubMed

    Yoo, Youngman; Martinez, Carlos; Youngblood, Jeffrey P

    2017-02-14

    The aim of this study is to develop methods to reinforce polymeric microspheres with cellulose nanocrystals (CNCs) to make eco-friendly microcapsules for a variety of applications such as medicines, perfumes, nutrients, pesticides, and phase change materials. Surface hydrophobization treatments for CNCs were performed by grafting poly(lactic acid) oligomers and fatty acids (FAs) to enhance the dispersion of nanoparticles in the polymeric shell. Then, a straightforward process is demonstrated to design sustained release microcapsules by the incorporation of the modified CNCs (mCNCs) in the shell structure. The combination of the mCNC dispersion with subsequent interfacial polyurea (PU) to form composite capsules as well as their morphology, composition, mechanical properties, and release rates were examined in this study. The PU microcapsules embedded with the mCNC were characterized by Fourier transform infrared spectroscopy (FT-IR) and thermogravimetric analysis (TGA). The morphologies of the microcapsules were characterized by optical microscopy (OM) and scanning electron microscope (SEM). The rupture stress and failure behavior of the microcapsules were determined through single-capsule compression tests. Oil-soluble Sudan II dye solution in mineral oil was utilized as a model hydrophobic fill, representing other latent fills with low partition coefficients, and their encapsulation efficiency was measured spectroscopically. The release rates of the encapsulated dye from the microcapsules were examined spectroscopically by both ethanol and 2-ethyl-1-hexanol medium at room temperature. The concentration of released dye was determined by using UV-vis absorption spectrometry (UV-vis). The mCNC embedded poly(urea-urethane) capsules have strong and dense walls, which function as excellent barriers against leakage due to their extended diffusion path length and ensure enough mechanical strength from rupture for handling or postprocessing.

  6. 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.

  7. 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.

  8. 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.

  9. Preparation and Properties of Melamine Urea-Formaldehyde Microcapsules for Self-Healing of Cementitious Materials

    PubMed Central

    Li, Wenting; Zhu, Xujing; Zhao, Nan; Jiang, Zhengwu

    2016-01-01

    Self-healing microcapsules were synthesized by in situ polymerization with a melamine urea-formaldehyde resin shell and an epoxy resin adhesive. The effects of the key factors, i.e., core–wall ratio, reaction temperature, pH and stirring rate, were investigated by characterizing microcapsule morphology, shell thickness, particle size distribution, mechanical properties and chemical nature. Microcapsule healing mechanisms in cement paste were evaluated based on recovery strength and healing microstructure. The results showed that the encapsulation ability, the elasticity modulus and hardness of the capsule increased with an increase of the proportion of shell material. Increased polymerization temperatures were beneficial to the higher degree of shell condensation polymerization, higher resin particles deposition on microcapsule surfaces and enhanced mechanical properties. For relatively low pH values, the less porous three-dimensional structure led to the increased elastic modulus of shell and the more stable chemical structure. Optimized microcapsules were produced at a temperature of 60 °C, a core-wall ratio of 1:1, at pH 2~3 and at a stirring rate of 300~400 r/min. The best strength restoration was observed in the cement paste pre-damaged by 30% fmax and incorporating 4 wt % of capsules. PMID:28773280

  10. The influence of HLB on the encapsulation of oils by complex coacervation.

    PubMed

    Rabisková, M; Valásková, J

    1998-01-01

    Microcapsules are used for the formulation of drug controlled release and drug targeting dosage forms. Encapsulated hydrophobic drugs are often applied as their solutions in plant oils. The uptake of the oils in the complex coacervate microcapsules can be improved by the addition of surfactants. In this study, soybean, olive and peanut oils were chosen as the representatives of plant oils. The well characterized complex coacervation of gelatin and acacia has been used to produce the microcapsules. The amount of encapsulated oil has been determined gravimetrically. The encapsulation of the oils was high (75-80%). When the surfactants with HLB values from 1.8 to 6.7 were used, the amount of encapsulated oil was high (65-85%). A significant decrease of the oil content in the microcapsules was found when Tween 61 with HLB = 9.6 had been added into the mixture. No oil was found inside the microcapsules from the coacervate emulsion mixture containing Tween 81 (HLB = 10) and Tween 80 (HLB = 15), respectively. The results of the experiment confirm the dependence of hydrophobic substance encapsulation on the HLB published recently for Squalan.

  11. 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

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

    PubMed

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

    2015-12-07

    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.

  13. Microencapsulation of porcine thyroid cell organoids within a polymer microcapsule construct.

    PubMed

    Yang, Yipeng; Opara, Emmanuel C; Liu, Yingbin; Atala, Anthony; Zhao, Weixin

    2017-02-01

    Hypothyroidism is a common condition of hormone deficiency, and oral administration of thyroid hormones is currently the only available treatment option. However, there are some disadvantages with this treatment modality including compliance challenges to patients. Therefore, a physiologically based alternative therapy for hypothyroidism with little or no side-effects is needed. In this study, we have developed a method for microencapsulating porcine thyroid cells as a thyroid hormone replacement approach. The hybrid wall of the polymer microcapsules permits thyroid hormone release while preventing immunoglobulin antibodies from entry. This strategy could potentially enable implantation of the microcapsule organoids containing allogeneic or xenogeneic thyroid cells to secret hormones over time without the need for immunosuppression of recipients. Porcine thyroid cells were isolated and encapsulated in alginate-poly-L-ornithine-alginate microcapsules using a microfluidic device. The porcine thyroid cells formed three-dimensional follicular spheres in the microcapsules with decent cell viability and proliferation. Thyroxine release from the encapsulated cells was higher than from unencapsulated cells ( P < 0.05) and was maintained during the entire duration of experiment (>28 days). These results suggest that the microencapsulated thyroid cell organoids may have the potential to be used for therapy and/or drug screening.

  14. 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.

  15. Microencapsulation of porcine thyroid cell organoids within a polymer microcapsule construct

    PubMed Central

    Yang, Yipeng; Opara, Emmanuel C; Liu, Yingbin; Zhao, Weixin

    2016-01-01

    Hypothyroidism is a common condition of hormone deficiency, and oral administration of thyroid hormones is currently the only available treatment option. However, there are some disadvantages with this treatment modality including compliance challenges to patients. Therefore, a physiologically based alternative therapy for hypothyroidism with little or no side-effects is needed. In this study, we have developed a method for microencapsulating porcine thyroid cells as a thyroid hormone replacement approach. The hybrid wall of the polymer microcapsules permits thyroid hormone release while preventing immunoglobulin antibodies from entry. This strategy could potentially enable implantation of the microcapsule organoids containing allogeneic or xenogeneic thyroid cells to secret hormones over time without the need for immunosuppression of recipients. Porcine thyroid cells were isolated and encapsulated in alginate-poly-L-ornithine-alginate microcapsules using a microfluidic device. The porcine thyroid cells formed three-dimensional follicular spheres in the microcapsules with decent cell viability and proliferation. Thyroxine release from the encapsulated cells was higher than from unencapsulated cells (P < 0.05) and was maintained during the entire duration of experiment (>28 days). These results suggest that the microencapsulated thyroid cell organoids may have the potential to be used for therapy and/or drug screening. PMID:27708182

  16. Alginate-based microcapsules generated with the coaxial electrospray method for clinical application.

    PubMed

    Barron, Catherine; He, Jia-Qiang

    2017-09-01

    Alginate-based microencapsulation of cells has made a significant impact on the fields of regenerative medicine and tissue engineering mainly because of its ability to provide immunoisolation for the encapsulated material. This characteristic has allowed for the successful transplantation of non-autologous cells in several clinical trials for life threatening conditions, such as diabetes, myocardial infarction, and neurodegenerative disorders. Methods for alginate hydrogel microencapsulation have been well developed for various types of cells and can generate microcapsules of different diameters, degradation time, and composition. It appears the most prominent and successful method in clinical applications is the coaxial electrospray method, which can be used to generate both homogenous and non-homogeneous microcapsules with uniform size on the order of 100 μm. The present review aims to discuss why alginate hydrogel is an ideal biomaterial for the encapsulation of cells, how alginate-based microcapsules are generated, and methods of modifying the microcapsules for specific clinical treatments. This review will also discuss clinical applications that have utilized alginate-based microencapsulation in the treatment of diabetes, ischemic heart disease, and neurodegenerative diseases.

  17. Stabilization and encapsulation of photosensitive resveratrol within yeast cell.

    PubMed

    Shi, Guorong; Rao, Liqun; Yu, Huazhong; Xiang, Hua; Yang, Hua; Ji, Runa

    2008-02-12

    The photosensitive resveratrol was successfully encapsulated in yeast cells for the first time, as characterized by FT-IR spectra, fluorescence and confocal micrographs of the yeast cells, resveratrol and microcapsules. The release characteristic of the obtained yeast-encapsulated resveratrol in simulated gastric fluid was evaluated, and its storage stability as a powder was investigated at 25 degrees C/75% relative humidity (RH), 25 degrees C/90% RH and 60 degrees C under the laboratory fluorescent lighting conditions (ca. 300 lx) or in the dark. Also, the scavenging capacity of yeast-encapsulated resveratrol on DPPH radical was compared with that of non-encapsulated resveratrol. It could be demonstrated clearly that no chemical changes occurred during the encapsulation. Besides, the DPPH radical-scavenging activity increased after the encapsulation. In addition, the yeast-encapsulated resveratrol exhibited good stability, and its bioavailability was enhanced as a result of increased solubility of resveratrol and sustained releasing.

  18. Colloidal capsules: nano- and microcapsules with colloidal particle shells.

    PubMed

    Bollhorst, Tobias; Rezwan, Kurosch; Maas, Michael

    2017-04-18

    Utilizing colloidal particles for the assembly of the shell of nano- and microcapsules holds great promise for the tailor-made design of new functional materials. Increasing research efforts are devoted to the synthesis of such colloidal capsules, by which the integration of modular building blocks with distinct physical, chemical, or morphological characteristics in a capsule's shell can result in novel properties, not present in previous encapsulation structures. This review will provide a comprehensive overview of the synthesis strategies and the progress made so far of bringing nano- and microcapsules with shells of densely packed colloidal particles closer to application in fields such as chemical engineering, materials science, or pharmaceutical and life science. The synthesis routes are categorized into the four major themes for colloidal capsule formation, i.e. the Pickering-emulsion based formation of colloidal capsules, the colloidal particle deposition on (sacrificial) templates, the amphiphilicity driven self-assembly of nanoparticle vesicles from polymer-grafted colloids, and the closely related field of nanoparticle membrane-loading of liposomes and polymersomes. The varying fields of colloidal capsule research are then further categorized and discussed for micro- and nano-scaled structures. Finally, a special section is dedicated to colloidal capsules for biological applications, as a diverse range of reports from this field aim at pharmaceutical agent encapsulation, targeted drug-delivery, and theranostics.

  19. Synthesis of multilayered alginate microcapsules for the sustained release of fibroblast growth factor-1

    PubMed Central

    Khanna, Omaditya; Moya, Monica L; Opara, Emmanuel C; Brey, Eric M

    2010-01-01

    Alginate microcapsules coated with a permselective poly-L-ornithine (PLO) membrane have been investigated for the encapsulation and transplantation of islets as a treatment for type 1 diabetes. The therapeutic potential of this approach could be improved through local stimulation of microvascular networks in order to meet mass transport demands of the encapsulated cells. Fibroblast growth factor-1 (FGF-1) is a potent angiogenic factor with optimal effect occurring when it is delivered in a sustained manner. In this paper, a technique is described for the generation of multilayered alginate microcapsules with an outer alginate layer that can be used for the delivery of FGF-1. The influence of alginate concentration and composition (high mannuronic acid (M) or guluronic acid (G) content) on outer layer size and stability, protein encapsulation efficiency, and release kinetics was investigated. The technique results in a stable outer layer of alginate with a mean thickness between 113–164 µm, increasing with alginate concentration and G-content. The outer layer was able to encapsulate and release FGF-1 for up to thirty days, with 1.25% of high G alginate displaying the most sustained release. The released FGF-1 retained its biologic activity in the presence of heparin, and the addition of the outer layer did not alter the permselectivity of the PLO coat. This technique could be used to generate encapsulation systems that deliver proteins to stimulate local neovascularization around encapsulated islets. PMID:20725969

  20. Sensing and Sensibility: Single-Islet-based Quality Control Assay of Cryopreserved Pancreatic Islets with Functionalized Hydrogel Microcapsules.

    PubMed

    Chen, Wanyu; Shu, Zhiquan; Gao, Dayong; Shen, Amy Q

    2016-01-21

    Despite decades of research and clinical studies of islet transplantations, finding simple yet reliable islet quality assays that correlate accurately with in vivo potency is still a major challenge, especially for real-time and single-islet-based quality assessment. Herein, proof-of-concept studies of a cryopreserved microcapsule-based quality control assays are presented for single islets. Individual rat pancreatic islets and fluorescent oxygen-sensitive dye (FOSD) are encapsulated in alginate hydrogel microcapsules via a microfluidic device. To test the susceptibility of the microcapsules and the FOSD to cryopreservation, the islet microcapsules containing FOSD are cryopreserved and the islet functionalities (adenosine triphosphate, static insulin release measurement, and oxygen consumption rate) are assessed after freezing and thawing steps. The cryopreserved islet capsules with FOSD remain functional after encapsulation and freezing/thawing procedures, validating a simple yet reliable individual-islet-based quality control method for the entire islet processing procedure prior to transplantation. This work also demonstrates that the functionality of cryopreserved islets can be improved by introducing trehalose into the routinely used cryoprotectant dimethyl sulfoxide. The functionalized alginate hydrogel microcapsules with embedded FOSD and optimized cryopreservation protocol presented in this work serve as a versatile islet quality assay and offer tremendous promise for tackling existing challenges in islet transplantation procedures.

  1. Cellulose acetate butyrate microcapsules containing dextran ion-exchange resins as self-propelled drug release system.

    PubMed

    Fundueanu, Gheorghe; Constantin, Marieta; Esposito, Elisabetta; Cortesi, Rita; Nastruzzi, Claudio; Menegatti, Enea

    2005-07-01

    Sulfopropylated dextran microspheres (SP-Ms), (Dm = 80 microm) loaded with a water soluble drug (Tetracycline HCl), were included in cellulose acetate butyrate (CAB) microcapsules. Spherical CAB microcapsules were obtained by oil in water (o/w) solvent evaporation method in the presence of an inert solvent as cyclohexane (CyH) or n-hexane (N-Hex), and different excipients (Phospholipon, Tween, Span, Eudragit RS 100). Chloroform was found to be the best solvent for the preparation of the microcapsules. Also, the sphericity as well as the porosity of the microcapsules was controlled by the presence of an inert solvent. The final concentration of the drug in CAB microparticles was up to 25% (w/w). The key factors for the successful preparation were also the viscosity of the polymer, while the wettability of the resulted microcapsules, the temperature of the preparation, and the porosity have modulated the release of the drug. The higher is the amount of encapsulated microspheres the thinner is the CAB wall between the compartments created by their incorporation. When these microspheres come in contact with the release medium, the pressure created by their swelling breaks the polymer film and the drug starts to be released. The more drug is released in phosphate buffer the higher is the swelling degree of the encapsulated ion exchange resins and the force created by their supplementary swelling will break the more resistants walls. In this way a self-propelled drug release is achieved, until almost all drug was eliberated.

  2. Reviewing the use of ethylcellulose, methylcellulose and hypromellose in microencapsulation. Part 2: Techniques used to make microcapsules.

    PubMed

    Rogers, True L; Wallick, Dave

    2011-11-01

    This three-part review has been developed following the evaluation of literature where ethylcellulose, methylcellulose or hypromellose was used to make microcapsules. Parts 1 and 3 of the review are published as separate papers. Part 1 covers the various materials used to formulate microcapsules, and Part 3 covers the various end-use applications for microcapsules. In the current paper, Part 2 covers the techniques used to make microcapsules. Examples of techniques to be covered include temperature-induced phase separation, emulsion solvent evaporation, solvent evaporation, film coating, nonsolvent addition and spray drying. It is hoped that formulators can use Part 2 to understand how to formulate microcapsules using these encapsulating polymers. SciFinder was utilized to perform the literature search. SciFinder leverages literature databases, such as Chemical Abstracts Service Registry and Medline. A total of 379 references were identified during the review. The need for a three-part review reflects the extensive amount of literature identified concerning these three encapsulating polymers.

  3. 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.

  4. 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.

  5. Production and evaluation of dry alginate-chitosan microcapsules as an enteric delivery vehicle for probiotic bacteria.

    PubMed

    Cook, Michael T; Tzortzis, George; Charalampopoulos, Dimitris; Khutoryanskiy, Vitaliy V

    2011-07-11

    This study investigates the production of alginate microcapsules, which have been coated with the polysaccharide chitosan, and evaluates some of their properties with the intention of improving the gastrointestinal viability of a probiotic ( Bifidobacterium breve ) by encapsulation in this system. The microcapsules were dried by a variety of methods, and the most suitable was chosen. The work described in this Article is the first report detailing the effects of drying on the properties of these microcapsules and the viability of the bacteria within relative to wet microcapsules. The pH range over which chitosan and alginate form polyelectrolyte complexes was explored by spectrophotometry, and this extended into swelling studies on the microcapsules over a range of pHs associated with the gastrointestinal tract. It was shown that chitosan stabilizes the alginate microcapsules at pHs above 3, extending the stability of the capsules under these conditions. The effect of chitosan exposure time on the coating thickness was investigated for the first time by confocal laser scanning microscopy, and its penetration into the alginate matrix was shown to be particularly slow. Coating with chitosan was found to increase the survival of B. breve in simulated gastric fluid as well as prolong its release upon exposure to intestinal pH.

  6. 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. Copyright © 2014 Elsevier Ltd. All rights reserved.

  7. Synbiotic Microcapsules That Enhance Microbial Viability during Nonrefrigerated Storage and Gastrointestinal Transit

    PubMed Central

    Crittenden, Ross; Weerakkody, Rangika; Sanguansri, Luz; Augustin, MaryAnn

    2006-01-01

    A Bifidobacterium infantis strain was microencapsulated within a film-forming protein-carbohydrate-oil emulsion. This novel encapsulant incorporated prebiotics and substantially protected the bacterium during nonrefrigerated storage and gastrointestinal transit. The dried microcapsules were small (15 to 20 μm), had low water activity (0.2 to 0.3), and rapidly released the bacteria in simulated intestinal fluid. PMID:16517688

  8. 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.

  9. 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.

  10. Formulation for Oral Delivery of Lactoferrin Based on Bovine Serum Albumin and Tannic Acid Multilayer Microcapsules

    NASA Astrophysics Data System (ADS)

    Kilic, Ece; Novoselova, Marina V.; Lim, Su Hui; Pyataev, Nikolay A.; Pinyaev, Sergey I.; Kulikov, Oleg A.; Sindeeva, Olga A.; Mayorova, Oksana A.; Murney, Regan; Antipina, Maria N.; Haigh, Brendan; Sukhorukov, Gleb B.; Kiryukhin, Maxim V.

    2017-03-01

    Lactoferrin (Lf) has considerable potential as a functional ingredient in food, cosmetic and pharmaceutical applications. However, the bioavailability of Lf is limited as it is susceptible to digestive enzymes in gastrointestinal tract. The shells comprising alternate layers of bovine serum albumin (BSA) and tannic acid (TA) were tested as Lf encapsulation system for oral administration. Lf absorption by freshly prepared porous 3 μm CaCO3 particles followed by Layer-by-Layer assembly of the BSA-TA shells and dissolution of the CaCO3 cores was suggested as the most efficient and harmless Lf loading method. The microcapsules showed high stability in gastric conditions and effectively protected encapsulated proteins from digestion. Protective efficiency was found to be 76 ± 6% and 85 ± 2%, for (BSA-TA)4 and (BSA-TA)8 shells, respectively. The transit of Lf along the gastrointestinal tract (GIT) of mice was followed in vivo and ex vivo using NIR luminescence. We have demonstrated that microcapsules released Lf in small intestine allowing 6.5 times higher concentration than in control group dosed with the same amount of free Lf. Significant amounts of Lf released from microcapsules were then absorbed into bloodstream and accumulated in liver. Suggested encapsulation system has a great potential for functional foods providing lactoferrin.

  11. Formulation for Oral Delivery of Lactoferrin Based on Bovine Serum Albumin and Tannic Acid Multilayer Microcapsules

    PubMed Central

    Kilic, Ece; Novoselova, Marina V.; Lim, Su Hui; Pyataev, Nikolay A.; Pinyaev, Sergey I.; Kulikov, Oleg A.; Sindeeva, Olga A.; Mayorova, Oksana A.; Murney, Regan; Antipina, Maria N.; Haigh, Brendan; Sukhorukov, Gleb B.; Kiryukhin, Maxim V.

    2017-01-01

    Lactoferrin (Lf) has considerable potential as a functional ingredient in food, cosmetic and pharmaceutical applications. However, the bioavailability of Lf is limited as it is susceptible to digestive enzymes in gastrointestinal tract. The shells comprising alternate layers of bovine serum albumin (BSA) and tannic acid (TA) were tested as Lf encapsulation system for oral administration. Lf absorption by freshly prepared porous 3 μm CaCO3 particles followed by Layer-by-Layer assembly of the BSA-TA shells and dissolution of the CaCO3 cores was suggested as the most efficient and harmless Lf loading method. The microcapsules showed high stability in gastric conditions and effectively protected encapsulated proteins from digestion. Protective efficiency was found to be 76 ± 6% and 85 ± 2%, for (BSA-TA)4 and (BSA-TA)8 shells, respectively. The transit of Lf along the gastrointestinal tract (GIT) of mice was followed in vivo and ex vivo using NIR luminescence. We have demonstrated that microcapsules released Lf in small intestine allowing 6.5 times higher concentration than in control group dosed with the same amount of free Lf. Significant amounts of Lf released from microcapsules were then absorbed into bloodstream and accumulated in liver. Suggested encapsulation system has a great potential for functional foods providing lactoferrin. PMID:28281573

  12. Formulation for Oral Delivery of Lactoferrin Based on Bovine Serum Albumin and Tannic Acid Multilayer Microcapsules.

    PubMed

    Kilic, Ece; Novoselova, Marina V; Lim, Su Hui; Pyataev, Nikolay A; Pinyaev, Sergey I; Kulikov, Oleg A; Sindeeva, Olga A; Mayorova, Oksana A; Murney, Regan; Antipina, Maria N; Haigh, Brendan; Sukhorukov, Gleb B; Kiryukhin, Maxim V

    2017-03-10

    Lactoferrin (Lf) has considerable potential as a functional ingredient in food, cosmetic and pharmaceutical applications. However, the bioavailability of Lf is limited as it is susceptible to digestive enzymes in gastrointestinal tract. The shells comprising alternate layers of bovine serum albumin (BSA) and tannic acid (TA) were tested as Lf encapsulation system for oral administration. Lf absorption by freshly prepared porous 3 μm CaCO3 particles followed by Layer-by-Layer assembly of the BSA-TA shells and dissolution of the CaCO3 cores was suggested as the most efficient and harmless Lf loading method. The microcapsules showed high stability in gastric conditions and effectively protected encapsulated proteins from digestion. Protective efficiency was found to be 76 ± 6% and 85 ± 2%, for (BSA-TA)4 and (BSA-TA)8 shells, respectively. The transit of Lf along the gastrointestinal tract (GIT) of mice was followed in vivo and ex vivo using NIR luminescence. We have demonstrated that microcapsules released Lf in small intestine allowing 6.5 times higher concentration than in control group dosed with the same amount of free Lf. Significant amounts of Lf released from microcapsules were then absorbed into bloodstream and accumulated in liver. Suggested encapsulation system has a great potential for functional foods providing lactoferrin.

  13. 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.

  14. Effect of microencapsulation of Lactobacillus salivarus 29 into alginate/chitosan/alginate microcapsules on viability and cytokine induction.

    PubMed

    Bajracharya, Prati; Islam, Mohammad Ariful; Jiang, Tao; Kang, Sang-Kee; Choi, Yun-Jaie; Cho, Chong-Su

    2012-01-01

    Harsh gastric condition causes low bioavailability of probiotics when supplied orally. Polymeric encapsulation has successfully protected bacteria from harsh gastric condition and ultimately increased persistency and multiplication at the targeted region. In this study, we encapsulated LS29 into ACA microcapsules and characterized them. The survivability and release of LS29 from LS29-loaded ACA microcapsules in SGF and SIF were studied. Encapsulation efficiency of LS29 in ACA microcapsules was 99.9%. Approximately 70% of bacteria survived at pH 2 by 120 min after encapsulation. Although not much difference of the survivability of LS29 encapsulated into ACA and FDACA was observed, freeze-drying improved the controlled-release of LS29 in SIF and also showed better storage survivability at 4°C for 8 weeks. Furthermore, investigation of in vitro production of cytokines in RAW264.7 showed high level of induction of TNF-α and IL-10. These in vitro results support that the LS29 might have a balanced immunomodulatory effect.

  15. Protection of Lactobacillus acidophilus NRRL-B 4495 under in vitro gastrointestinal conditions with whey protein/pullulan microcapsules.

    PubMed

    Çabuk, Burcu; Tellioğlu Harsa, Şebnem

    2015-12-01

    In this research, whey protein/pullulan (WP/pullulan) microcapsules were developed in order to assess its protective effect on the viability of Lactobacillus acidophilus NRRL-B 4495 under in vitro gastrointestinal conditions. Results demonstrated that WP/pullulan microencapsulated cells exhibited significantly (p ≤ 0.05) higher resistance to simulated gastric acid and bile salt. Pullulan incorporation into protein wall matrix resulted in improved survival as compared to free cells after 3 h incubation in simulated gastric solution. Moreover WP/pullulan microcapsules were found to release over 70% of encapsulated L. acidophilus NRRL-B 4495 cells within 1 h. The effect of encapsulation during refrigerated storage was also studied. Free bacteria exhibited 3.96 log reduction while, WP/pullulan encapsulated bacteria showed 1.64 log reduction after 4 weeks of storage. Copyright © 2015 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

  16. Release kinetics of salbutamol sulphate from wax coated microcapsules and tableted microcapsules.

    PubMed

    Raghuvanshi, R S; Tripathi, K P; Jayaswal, S B; Singh, J

    1992-01-01

    Microcapsules of salbutamol sulphate were prepared using beeswax and carnauba wax as coating materials. In vitro release kinetics were studied following the zero order, first order and Higuchi equations. Beeswax alone was not effective but beeswax and carnauba wax combinations were suitable in controlling the in vitro release of the drug. Microcapsules were compressed into tablets to get a controlled release oral dosage form. Release from tableted microcapsules was significantly more prolonged than the respective batches of the microcapsules. Best data fit with the highest correlation coefficient for the tableted microcapsules was obtained for first order.

  17. Novel sulfated glucomannan-barium-alginate microcapsules in islet transplantation: significantly decreased the secretion of monocyte chemotactic protein 1 and improved the activity of islet in rats.

    PubMed

    Chen, X; Zhang, L; Qi, Z; Guo, B; Zhong, L; Shen, B; Yan, Z; Zhang, J

    2009-12-01

    The sulfated glucomannan can be used to filter the heparin-binding properties of cytokines. In this study, novel sulfated glucomannan-barium-alginate (SGA) microcapsules were prepared to encapsulate islets with barium-alginate (ABa) and calcium alginate-poly-l-lysine (APA) microcapsules as controls. SD rat islets were purified as donor cells to Lewis rats that had been treated with streptozotocin. Intraperitoneal transplantation was performed with about 3000 islet equivalent (IEQ) rat. At week three after transplantation, the concentrations of monocyte chemotactic protein-1 (MCP-1), interleukin (IL)-1 beta, interferon (IFN)-gamma, and tumor necrosis factor (TNF)-alpha in intraperitoneal fluid were determined using ELISA. At week 8, the islet cell mass in the abdominal microcapsules was excised to test insulin release. The EB-FDA fluorescence staining method was used to observe the functional activity of the islet cells. Compared with ABa and APA microcapsules, SGA microcapsules showed significantly decreased MCP-1 secretion by beta-cells. Also, the concentrations of cytokines IL-1beta, IFN-gamma, and TNF-alpha were decreased significantly. The activity of the transplanted islets was significantly improved in SGA microcapsules, which shielded against cytokines better than ABa or APA microcapsules and may serve as novel method.

  18. 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

    2015-02-05

    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.

  19. Encapsulation of Liquids Via Extrusion--A Review.

    PubMed

    Tackenberg, Markus W; Kleinebudde, Peter

    2015-01-01

    Various encapsulation techniques are known for pharmaceutical applications. Extrusion is of minor importance. However, extrusion is used to obtain granules with encapsulate liquid active ingredients (AI) like essential oils and flavours for food applications since decades. Many of these AIs can be used for agrochemical, home care, and pharmaceutical products, too. Thus, the focus of this review is on the interdisciplinary presentation and evaluation of the available knowledge about the encapsulation process via extrusion. The desired microcapsule structure is discussed at the outset. The microcapsule is compared to the alternative glassy solid solution system, before an overview of suitable excipients is given. In the next section the development of the extrusion technique, used for encapsulation processes, is presented. Thereby, the focus is on encapsulation using twin-screw extruders. Additionally, the influence of the downstream processes on the products is discussed, too. The understanding of the physical processes during extrusion is essential for specifically adjustment of the desired product properties and thus, highlighted in this paper. Unfortunately not all processes, especially the mixing process, are well studied. Suggestions for further studies, to improve process understanding and product quality, are given, too. The last part of this review focuses on the characterization of the obtained granules, especially AI content, encapsulation efficiency, and storage stability. In conclusion, extrusion is a standard technique for flavour encapsulation, but future studies, may lead to more (pharmaceutical) applications and new products.

  20. Fabrication of redox and pH dual-responsive magnetic graphene oxide microcapsules via sonochemical method.

    PubMed

    Dong, Linlin; Shi, Chao; Guo, Lanlan; Yang, Ting; Sun, Yuexin; Cui, Xuejun

    2017-05-01

    In this study, the biocompatible redox and pH dual-responsive magnetic graphene oxide microcapsules (MGOMCs) were prepared by a simple sonochemical method. The disulfide bonds cross-linked the wall of MGOMCs were formed from the hydrosulfuryl on the surface of thiolated graphene oxide, which was synthesized by functionalizing graphene oxide with cysteine, showed an excellent redox-responsive property to control drugs release. Moreover, oleic acid modified Fe3O4 nanoparticles were encapsulated into the microcapsules successfully with the hydrophobic drugs dispersed in the hydroxy silicone oil. The MGOMCs possess distinguished magnetic property and pH-responsive ability. Besides, the microcapsules could be engulfed by Hela cells successfully due to the appropriate size and flexible shell. The MGOMCs could be a good carrier for hydrophobic drugs, especially the anticancer drugs.

  1. Formulation optimization of propranolol hydrochloride microcapsules employing central composite design.

    PubMed

    Shivakumar, H N; Patel, R; Desai, B G

    2008-01-01

    A central composite design was employed to produce microcapsules of propranolol hydrochloride by o/o emulsion solvent evaporation technique using a mixture of cellulose acetate butyrate as coat material and span-80 as an emulsifier. The effect of formulation variables namely levels of cellulose acetate butyrate (X(1)) and percentage of Span-80 (X(2)) on encapsulation efficiency (Y(1)), drug release at the end of 1.5 h (Y(2)), 4 h (Y(3)), 8 h (Y(4)), 14 h (Y(5)), and 24 h (Y(6)) were evaluated using the F test. Mathematical models containing only the significant terms were generated for each response parameter using multiple linear regression analysis and analysis of variance. Both the formulation variables exerted a significant influence (P <0.05) on Y(1) whereas the cellulose acetate butyrate level emerged as the lone factor which significantly influenced the other response parameters. Numerical optimization using desirability approach was employed to develop an optimized formulation by setting constraints on the dependent and independent variables. The experimental values of Y(1), Y(2), Y(3), Y(4), Y(5), and Y(6) for the optimized formulation was found to be 92.86+/-1.56% w/w, 29.58+/-1.22%, 48.56+/-2.56%, 60.85+/-2.35%, 76.23+/-3.16% and 95.12+/-2.41%, respectively which were in close agreement with those predicted by the mathematical models. The drug release from microcapsules followed first order kinetics and was characterized by Higuchi diffusion model. The optimized microcapsule formulation developed was found to comply with the USP drug release test-1 for extended release propranolol hydrochloride capsules.

  2. 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..

  3. Sustained release bioadhesive effervescent ketoconazole microcapsules tabletted for vaginal delivery.

    PubMed

    Karasulu, H Y; Taneri, F; Sanal, E; Güneri, T; Ertan, G

    2002-01-01

    Microcapsules of ketoconazole with 1:1 and 1:2 core-wall ratios were prepared by means of the phase separation technique using sodium carboxymethylcellulose as a coating material. The microcapsules were mixed with effervescent granules and were tabletted. Dissolution studies of microcapsules, tabletted microcapsules and commercial ovules were carried out with a new basket method (horizontal rotating basket). A good sustained action was obtained with tablets. Micromeritic investigations were carried out on microcapsules in order to standardize the microcapsule product and to optimize the pilot production of the dosage forms prepared with these microcapsules. Bulk volume and weight, tapping volume and weight, fluidity, angle of repose, weight deviation, relative deviation, particle size distribution, density and porosity values of the microcapsules were determined. In addition, to evaluate whether some kind of glidant will be needed during tabletting of microcapsules, the Hausner ratio o and consolidaton index were also calculated and it may be concluded that microcapsules do not need any glidant.

  4. On spray drying of oxidized corn starch cross-linked gelatin microcapsules for drug release.

    PubMed

    Dang, Xugang; Yang, Mao; Shan, Zhihua; Mansouri, Shahnaz; May, Bee K; Chen, Xiaodong; Chen, Hui; Woo, Meng Wai

    2017-05-01

    Spray-dried gelatin/oxidized corn starch (G/OCS) microcapsules were produced for drug release application. The prepared microcapsules were characterized through a scanning electron microscope (SEM) picture and thermogravimetric analysis (TGA). The swelling characteristics of the G/OCS microcapsules and release properties of vitamin C were then investigated. The results from structural analysis indicated that the presence of miscibility and compatibility between oxidized corn starch and gelatin, and exhibits high thermal stability up to 326°C. The swelling of G/OCS microcapsules increased with increasing pH and reduced with decreasing ionic strength, attributed to the cross-linking between gelatin and oxidized corn starch, ionization of functional groups. Vitamin C release characteristic revealed controlled release behavior in the first 3h of contact with an aqueous medium. This release behavior was independent of the swelling behavior indicating the potential of the encapsulating matrix to produce controlled release across a spectrum of pH environment. Copyright © 2016 Elsevier B.V. All rights reserved.

  5. Electrosprayed Multi-Core Alginate Microcapsules as Novel Self-Healing Containers

    NASA Astrophysics Data System (ADS)

    Hia, Iee Lee; Pasbakhsh, Pooria; Chan, Eng-Seng; Chai, Siang-Piao

    2016-10-01

    Alginate microcapsules containing epoxy resin were developed through electrospraying method and embedded into epoxy matrix to produce a capsule-based self-healing composite system. These formaldehyde free alginate/epoxy microcapsules were characterized via light microscope, field emission scanning electron microscope, fourier transform infrared spectroscopy and thermogravimetric analysis. Results showed that epoxy resin was successfully encapsulated within alginate matrix to form porous (multi-core) microcapsules with pore size ranged from 5-100 μm. The microcapsules had an average size of 320 ± 20 μm with decomposition temperature at 220 °C. The loading capacity of these capsules was estimated to be 79%. Under in situ healing test, impact specimens showed healing efficiency as high as 86% and the ability to heal up to 3 times due to the multi-core capsule structure and the high impact energy test that triggered the released of epoxy especially in the second and third healings. TDCB specimens showed one-time healing only with the highest healing efficiency of 76%. The single healing event was attributed by the constant crack propagation rate of TDCB fracture test. For the first time, a cost effective, environmentally benign and sustainable capsule-based self-healing system with multiple healing capabilities and high healing performance was developed.

  6. Experimental Study on Mechanical Properties and Porosity of Organic Microcapsules Based Self-Healing Cementitious Composite.

    PubMed

    Wang, Xianfeng; Sun, Peipei; Han, Ningxu; Xing, Feng

    2017-01-01

    Encapsulation of healing agents embedded in a material matrix has become one of the major approaches for achieving self-healing function in cementitious materials in recent years. A novel type of microcapsules based self-healing cementitious composite was developed in Guangdong Provincial Key Laboratory of Durability for Marine Civil Engineering, Shenzhen University. In this study, both macro performance and the microstructure of the composite are investigated. The macro performance was evaluated by employing the compressive strength and the dynamic modulus, whereas the microstructure was represented by the pore structure parameters such as porosity, cumulative-pore volume, and average-pore diameter, which are significantly correlated to the pore-size distribution and the compressive strength. The results showed that both the compressive strength and the dynamic modulus, as well as the pore structure parameters such as porosity, cumulative-pore volume, and average-pore diameter of the specimen decrease to some extent with the amount of microcapsules. However, the self-healing rate and the recovery rate of the specimen performance and the pore-structure parameters increase with the amount of microcapsules. The results should confirm the self-healing function of microcapsules in the cementitious composite from macroscopic and microscopic viewpoints.

  7. Experimental Study on Mechanical Properties and Porosity of Organic Microcapsules Based Self-Healing Cementitious Composite

    PubMed Central

    Wang, Xianfeng; Sun, Peipei; Han, Ningxu; Xing, Feng

    2017-01-01

    Encapsulation of healing agents embedded in a material matrix has become one of the major approaches for achieving self-healing function in cementitious materials in recent years. A novel type of microcapsules based self-healing cementitious composite was developed in Guangdong Provincial Key Laboratory of Durability for Marine Civil Engineering, Shenzhen University. In this study, both macro performance and the microstructure of the composite are investigated. The macro performance was evaluated by employing the compressive strength and the dynamic modulus, whereas the microstructure was represented by the pore structure parameters such as porosity, cumulative-pore volume, and average-pore diameter, which are significantly correlated to the pore-size distribution and the compressive strength. The results showed that both the compressive strength and the dynamic modulus, as well as the pore structure parameters such as porosity, cumulative-pore volume, and average-pore diameter of the specimen decrease to some extent with the amount of microcapsules. However, the self-healing rate and the recovery rate of the specimen performance and the pore-structure parameters increase with the amount of microcapsules. The results should confirm the self-healing function of microcapsules in the cementitious composite from macroscopic and microscopic viewpoints. PMID:28772382

  8. Electrosprayed Multi-Core Alginate Microcapsules as Novel Self-Healing Containers.

    PubMed

    Hia, Iee Lee; Pasbakhsh, Pooria; Chan, Eng-Seng; Chai, Siang-Piao

    2016-10-03

    Alginate microcapsules containing epoxy resin were developed through electrospraying method and embedded into epoxy matrix to produce a capsule-based self-healing composite system. These formaldehyde free alginate/epoxy microcapsules were characterized via light microscope, field emission scanning electron microscope, fourier transform infrared spectroscopy and thermogravimetric analysis. Results showed that epoxy resin was successfully encapsulated within alginate matrix to form porous (multi-core) microcapsules with pore size ranged from 5-100 μm. The microcapsules had an average size of 320 ± 20 μm with decomposition temperature at 220 °C. The loading capacity of these capsules was estimated to be 79%. Under in situ healing test, impact specimens showed healing efficiency as high as 86% and the ability to heal up to 3 times due to the multi-core capsule structure and the high impact energy test that triggered the released of epoxy especially in the second and third healings. TDCB specimens showed one-time healing only with the highest healing efficiency of 76%. The single healing event was attributed by the constant crack propagation rate of TDCB fracture test. For the first time, a cost effective, environmentally benign and sustainable capsule-based self-healing system with multiple healing capabilities and high healing performance was developed.

  9. 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.

  10. Electrosprayed Multi-Core Alginate Microcapsules as Novel Self-Healing Containers

    PubMed Central

    Hia, Iee Lee; Pasbakhsh, Pooria; Chan, Eng-Seng; Chai, Siang-Piao

    2016-01-01

    Alginate microcapsules containing epoxy resin were developed through electrospraying method and embedded into epoxy matrix to produce a capsule-based self-healing composite system. These formaldehyde free alginate/epoxy microcapsules were characterized via light microscope, field emission scanning electron microscope, fourier transform infrared spectroscopy and thermogravimetric analysis. Results showed that epoxy resin was successfully encapsulated within alginate matrix to form porous (multi-core) microcapsules with pore size ranged from 5–100 μm. The microcapsules had an average size of 320 ± 20 μm with decomposition temperature at 220 °C. The loading capacity of these capsules was estimated to be 79%. Under in situ healing test, impact specimens showed healing efficiency as high as 86% and the ability to heal up to 3 times due to the multi-core capsule structure and the high impact energy test that triggered the released of epoxy especially in the second and third healings. TDCB specimens showed one-time healing only with the highest healing efficiency of 76%. The single healing event was attributed by the constant crack propagation rate of TDCB fracture test. For the first time, a cost effective, environmentally benign and sustainable capsule-based self-healing system with multiple healing capabilities and high healing performance was developed. PMID:27694922

  11. 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

  12. 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.

  13. Improvement of Stability and Antioxidant Activities by Using Phycocyanin - Chitosan Encapsulation Technique

    NASA Astrophysics Data System (ADS)

    Suzery, Meiny; Hadiyanto; Majid, Dian; Setyawan, Deny; Sutanto, Heri

    2017-02-01

    Encapsulation is a coating process to improve the stability of bioactive compounds. Phycocyanin with high antioxidant activity has been encapsulated with chitosan in microcapsules form. In this study aims to determine the best conditions in the encapsulation process using the extrusion method, characterization of the physicochemical properties of the microcapsules, antioxidant activity test using DPPH, in vitro release performance and evaluate the storage stability against temperature. The results of the encapsulation process is obtained: Na-TPP is better than Na-citrate as crosslinker and chitosan content 3% as a coating with ratio of chitosan to phycocyanin ratio 1: 1. Test of antioxidant activity also showed encapsulation with chitosan content 3% has the highest antioxidant activity. Morphological analysis microcapsules were found to have compact spherical shape with diameter range 900-1000 µm. In vitro release testing showed a quick release in an acidic environment (SGF) for 2 hours and slowly release under alkaline conditions (SIF) for 8 hours under mechanical stirring at 37°C. Phycocyanin much more stable against temperature during storage in microcapsules.

  14. Islets immunoisolation using encapsulation and PEGylation, simultaneously, as a novel design.

    PubMed

    Nabavimanesh, Mohammad Mahdi; Hashemi-Najafabadi, Sameereh; Vasheghani-Farahani, Ebrahim

    2015-04-01

    The most important obstacle in islets transplantation for the treatment of diabetes is graft rejection by the host immune system. To solve this problem, immunosuppressive drugs should be used, but they may have several side effects. To overcome these problems, islets immunoisolation systems such as encapsulation and PEGylation have been developed. The aim of this study was to investigate the possibility of using encapsulation and PEGylation techniques simultaneously (as a novel design) for immunocamouflaging the islets of Langerhans. For this purpose, the attachment of poly-L-ornithine (PLO) onto the surface of alginate microcapsules and activated methoxy polyethylene glycol (mPEG) onto alginate-PLO microcapsules was verified by Fourier transform infrared analysis and scanning electron microscopy. Viability of the free and encapsulated islets up to the 7th day was approved by acridine orange (AO)/propidium iodide (PI). The obtained results from lymphocytes co-culturing with free and encapsulated islets (in different designs of microcapsules with one to three layers) showed that encapsulation generally reduces the immune response against the islets. However, the addition of PLO and mPEG as second and third layers to the surface of alginate microcapsules decreased interleukine-2 (IL-2) secretion against the islets more and more. Finally, two different activated mPEG, mPEG-succinimidyl carbonate (mPEG-SC) and mPEG-succinimidylvaleric acid (mPEG-SVA), used separately on the surface of microcapsules were investigated, and the results showed that IL-2 secretion was reduced 14.3% and 37.5% in comparison with the alginate-PLO microcapsules, respectively. On the other hand, mPEG-SVA was more effective than mPEG-SC, so it decreased IL-2 secretion 27.1% more than mPEG-SC.

  15. Gelatin microcapsules for enhanced microwave tumor hyperthermia

    NASA Astrophysics Data System (ADS)

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

    2015-02-01

    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.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. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr07104b

  16. Facile preparation of robust microcapsules by manipulating metal-coordination interaction between biomineral layer and bioadhesive layer.

    PubMed

    Zhang, Lei; Shi, Jiafu; Jiang, Zhongyi; Jiang, Yanjun; Meng, Ruijie; Zhu, Yuanyuan; Liang, Yanpeng; Zheng, Yang

    2011-02-01

    A novel approach combining biomimetic mineralization and bioadhesion is proposed to prepare robust and versatile organic-inorganic hybrid microcapsules. More specifically, these microcapsules are fabricated by sequential deposition of inorganic layer and organic layer on the surface of CaCO(3) microparticles, followed by the dissolution of CaCO(3) microparticles using EDTA. During the preparation process, protamine induces the hydrolysis and condensation of titania or silica precursor to form the inorganic layer or the biomineral layer. The organic layer or bioadhesive layer was formed through the rapid, spontaneous oxidative polymerization of dopamine into polydopamine (PDA) on the surface of the biomineral layer. There exist multiple interactions between the inorganic layer and the organic layer. Thus, the as-prepared organic-inorganic hybrid microcapsules acquire much higher mechanical stability and surface reactivity than pure titania or pure silica microcapsules. Furthermore, protamine/titania/polydopamine hybrid microcapsules display superior mechanical stability to protamine/silica/polydopamine hybrid microcapsules because of the formation of Ti(IV)-catechol coordination complex between the biomineral layer and the bioadhesive layer. As an example of application, three enzymes are respectively immobilized through physical encapsulation in the lumen, in situ entrapment within the wall and chemical attachment on the out surface of the hybrid microcapsules. The as-constructed multienzyme system displays higher catalytic activity and operational stability. Hopefully, the approach developed in this study will evolve as a generic platform for facile and controllable preparation of organic-inorganic hybrid materials with different compositions and shapes for a variety of applications in catalysis, sensor, drug/gene delivery.

  17. 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.

  18. 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.

  19. 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.

  20. Effect of whey protein agglomeration on spray dried microcapsules containing Saccharomyces boulardii.

    PubMed

    Duongthingoc, Diep; George, Paul; Katopo, Lita; Gorczyca, Elizabeth; Kasapis, Stefan

    2013-12-01

    This work investigates the effect of whey protein agglomeration on the survivability of Saccharomyces boulardii within spray dried microcapsules. It attempts to go beyond phenomenological observations by establishing a relationship between physicochemical characteristics of the polymeric matrix and its effect on probiotic endurance upon spray drying. It is well known that this type of thermal shock has lethal consequences on the yeast cells. To avoid such undesirable outcome, we take advantage of the early agglomeration phenomenon observed for whey protein by adjusting the pH value of preparations close to isoelectric point (pH 4-5). During the subsequent process of spray drying, development of whey protein agglomerates induces formation of an early crust, and the protein in this molten globular state creates a cohesive network encapsulating the yeast cells. It appears that the early crust formation at a given sample pH and temperature regime during spray drying benefits the survivability of S. boulardii within microcapsules.

  1. 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

  2. Preparation of Hemoglobin-Containing Microcapsules.

    DTIC Science & Technology

    1981-06-01

    were suspended in saline for storage in a refrigerator. Although in these microencapsulation experiments, the Hb was not denatured, the microcapsules ... microencapsulated Hb, l.O-ml sample of the microcapsule suspension was diluted with 10 ml 0.9% NaCI. The absorption spectrum was taken immediately after dilution...AD A135 634 PREPARATION OF HEMOGLOBIN CONTA NING MICROCAPSULES (U) I/ ,R 224 AM OS NTERNATIDNAL MENOPARKO CA REYES AUNN8 SRI-2254-1 DAMD17-80-C-01?7

  3. Preparation of Hemoglobin-Containing Microcapsules.

    DTIC Science & Technology

    1982-04-01

    L -i2 801 PREPARRTION OF HEMOGLOBIN-CONTAINING MICROCAPSULES (U) i/i I SRI INTERNATIONAL MENLO PRK CA Z REYES APR 82 UNLSSFE SRI1-2254-2 DRMDi,7-8@-C...R oI• _ AD I PREPARATION OF HEMOGLOBIN- /2 o ) CONTAINING MICROCAPSULES . 00 ANNUAL AND FINAL REPORT ZOILA REYES, Ph.D. APRIL 1982 Supported by U.S...1/31/82) PREPARATION OF HEMOGLOBIN-CONTAINING MICROCAPSULES 6. PERFORMING ORG. REPOR’ NUMBER 2254-2 7. AUTHOR(s) 8. CONTRACT OR GRANT NUMBER(s) Zoila

  4. 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.

  5. Novel NaCS-CS-PPS microcapsules as a potential enzyme-triggered release carrier for highly-loading 5-ASA.

    PubMed

    Wu, Qing-Xi; Yao, Shan-Jing

    2013-09-01

    In order to develop novel spherical micro-drug-carriers, an orifice-polymerization method was used to prepare spherical microcapsules which were composed of chemically crosslinked chitosan (CS) with sodium cellulose sulfate (NaCS) and sodium polyphosphate (PPS). 5-Aminosalicylic acid (5-ASA) was chosen as a model drug. The microcapsules prepared had an average diameter of 1.90 mm with loading efficiency of 60.77% and encapsulation efficiency of 90.03%. SEM results showed that the microcapsules had a double-walled capsule structure with an outer wall thickness of approximately 4.40 μm and inner wall (shell) thickness of approximately 187.14 μm. SEM transection images of the microcapsules showed that 5-ASA entrapped in the microcapsule was in a crystal form. The results of in vitro swelling/erosion and release analysis showed that the drug was preferentially and completely released in simulated colonic fluid (SCF, pH 6.4) under the mechanism of Anomalous transport. All these results indicate that the microcapsules could be a good candidate as an enzyme-triggered controlled release drug carrier.

  6. Patterned surfaces segregate compliant microcapsules.

    PubMed

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

    2007-01-30

    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 microcapsules 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.

  7. 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.

  8. Programmable Microcapsules from Self-Immolative Polymers

    SciTech Connect

    Esser-Kahn, Aaron P.; Sottos, Nancy R.; White, Scott R.; Moore, Jeffrey S.

    2010-01-01

    For the autonomous repair of damaged materials, microcapsules are needed that release their contents in response to a variety of physical and chemical phenomena, not just by direct mechanical rupture. Herein we report a general route to programmable microcapsules. This method creates core-shell microcapsules with polymeric shell walls composed of self-immolative polymer networks. The polymers in these networks undergo a head-to-tail depolymerization upon removal of the triggering end group, leading to breakdown of the shell wall and subsequent release of the capsule’s liquid interior. We report microcapsules with shell walls bearing both Boc and Fmoc triggering groups. The capsules release their contents only under conditions known to remove these triggering groups; otherwise, they retain their contents under a variety of conditions. In support of the proposed release mechanism, the capsule shell walls were observed to undergo physical cracking upon exposure to the triggering conditions.

  9. 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

    2003-07-09

    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.

  10. 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.

  11. 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

  12. Do encapsulated heat storage materials really retain their original thermal properties?

    PubMed

    Chaiyasat, Preeyaporn; Noppalit, Sayrung; Okubo, Masayoshi; Chaiyasat, Amorn

    2015-01-14

    The encapsulation of Rubitherm®27 (RT27), which is one of the most common commercially supplied heat storage materials, by polystyrene (PS), polydivinyl benzene (PDVB) and polymethyl methacrylate (PMMA) was carried out using conventional radical microsuspension polymerization. The products were purified to remove free RT27 and free polymer particles without RT27. In the cases of PS and PDVB microcapsules, the latent heats of melting and crystallization for RT27 ( and , J/g-RT27) were clearly decreased by the encapsulation. On the other hand, those of the PMMA microcapsules were the same as pure RT27. A supercooling phenomenon was observed not only for PS and PDVB but also for the PMMA microcapsules. These results indicate that the thermal properties of the heat storage materials encapsulated depend on the type of polymer shells, i.e., encapsulation by polymer shell changes the thermal properties of RT27. This is quite different from the idea of other groups in the world, in which they discussed the thermal properties based on the ΔHm and ΔHc values expressed in J/g-capsule, assuming that the thermal properties of the heat storage materials are not changed by the encapsulation. Hereafter, this report should raise an alarm concerning the "wrong" common knowledge behind developing the encapsulation technology of heat storage materials.

  13. Reconfigurable Nano-Plasmonics Holography

    DTIC Science & Technology

    2013-04-01

    30 Sept. 2012 4. TITLE AND SUBTITLE Reconfigurable Nano -Plasmonics Holography 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT...of plasmonic holography by Reconfigurable Surface Plasmon Phase Modulators from micro -electromechanical devices. High dielectric constant...integration of the above components in a SP modulator device. 15. SUBJECT TERMS surface plasmon, nano -photonics, phase modulation, reconfigurable Air Force

  14. Encapsulation of yeast cells in colloidosomes.

    PubMed

    Keen, Polly H R; Slater, Nigel K H; Routh, Alexander F

    2012-01-17

    Polymeric colloidosomes encapsulating viable Baker's yeast cells were prepared. To make the capsules, an aqueous suspension of 153 nm poly(methyl methacrylate-co-butyl acrylate) latex particles plus yeast cells is emulsified in a continuous phase of sunflower oil. By adding a small amount of ethanol to the oil phase, the latex particles at the surface of the emulsion droplets aggregate, forming the colloidosome shells. The microcapsules have been examined using optical, confocal, and scanning electron microscopies. The viability of the yeast cells was tested using fluorescent molecular probes. The encapsulated Baker's yeast cells were able to metabolize glucose from solution, although at a slower rate compared to nonencapsulated yeast. This demonstrates diffusion limitation through the colloidosome shell. The diffusive resistance could be increased by manufacturing colloidosomes with a double latex shell. © 2011 American Chemical Society

  15. 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.

  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.

  17. Study on preparation of β-cyclodextrin encapsulation tea extract.

    PubMed

    Haidong, Liang; Fang, Yu; Zhihong, Tong; Changle, Ren

    2011-11-01

    Microencapsulation of ethanol extract of tea was performed in this study. In order to microencapsulate, β-cyclodextrin was used as wall material. Ethanol extract of tea was used as the core material. Microcapsules in the solid form were obtained by drying the emulsions. RSM showed that optimal processing parameters were as followings: core material/wall material 1/4, β-cyclodextrin content 16%, stirring time 30 min and stirring temperature 200°C. Pharmacological activities of β-cyclodextrin encapsulation tea extract were determined. It was found that β-cyclodextrin encapsulation tea extract could enhance BMD, BMC and bone Ca, Zn and Cu contents. In addition, β-cyclodextrin encapsulation tea extract could still reduce blood Ca contents. These results indicated that β-cyclodextrin encapsulation tea extract was useful for improving bone quality in aged animals.

  18. Development of injectable microcapsules for use in the treatment of narcotic addiction.

    PubMed

    Thies, C

    1976-01-01

    Injectible microcapsules containing narcotic antagonists have been prepared with dl-poly (lactic acid) as the coating material. The encapsulation technology has developed to the point that high yields of less than 180 mu capsules can be prepared routinely. Such capsules with an initial payload of 50 wt. % naltrexone pamoate provide 60-90% antagonism to the action of morphine 28 days after injection into mice as a peanut oil/aluminum monostearate suspension at a dose level of 40 miligrams naltrexone pamoate/ kg. mouse.

  19. Development of injectable microcapsules for use in the treatment of narcotic addiction.

    PubMed

    Thies, C

    1975-01-01

    Injectible microcapsules containing narcotic antagonists have been prepared with dl-poly (lactic acid) as the coating material. The encapsulation technology has been developed to the point that high yields of less than 180 mu capsules can be prepared routinely. Such capsules with an initial payload of 50 wt. per cent naltrexone pamoate provide 60-90 per cent antagonism to the action of morphine 28 days after injection into mice as a peanut oil/aluminum monostearate suspension at a dose level of 40 miligrams naltrexone pamoate/kg. mouse.

  20. Hollow chitosan-alginate multilayer microcapsules as drug delivery vehicle: doxorubicin loading and in vitro and in vivo studies.

    PubMed

    Zhao, Qinghe; Han, Baosan; Wang, Zhaohai; Gao, Changyou; Peng, Chenghong; Shen, Jiacong

    2007-03-01

    We report here the loading of the antitumor drug doxorubicin (DOX) in preformed multilayer microcapsules and its application in tumor treatment assayed by in vitro cell culture and in vivo animal experiments. The microcapsules, consisting completely of polysaccharides, were fabricated by deposition of oppositely charged chitosan and alginate onto carboxylmethyl cellulose (CMC)-doped CaCO(3) colloidal particles in a layer-by-layer fashion, followed by cross-linking with glutaraldehyde and decomposition of the cores by disodium ethylenediaminetetraacetic acid. The microcapsules as prepared contain negatively charged CMC-either in a free state or very possibly coupled with the excess chitosan of the first layer. They showed a strong ability to accumulate the positively charged DOX with a factor of tens to hundreds; that is, the drug concentration within the microcapsules was hundreds of times higher than the feeding concentration. Confocal microscopy and transmission electron microscopy revealed homogeneous distribution of the drug. The encapsulated DOX could be released again, following a diffusion-controlled model at the initial stage. In vitro experiments showed that the encapsulated drug can effectively induce the apoptosis of HepG2 tumor cells, as shown by various microscopy techniques after acridine orange, Hoechst 33342, and osmium tetraoxide staining. By seeding the HepG2 hepatoma cells into BALB/c/nu mice, tumors were created for the experimental studies. The results showed that the encapsulated DOX had better efficacy than that of the free drug in terms of tumor inhibition in a 4-week in vivo culture period.

  1. Encapsulated Multifunction Corrosion Inhibitive Primer.

    DTIC Science & Technology

    1983-11-01

    Optimization of Microcapsule Preparation ...................... 162 24 Optimized Procedure for Polyurea Microencapsulation ................... 166 25... microcapsules , which suggests that a nearly quantitative yield of microencapsulated inhibitor was achieved. The burst ratio is defined as the conductivity after...effectiveness of the microencapsulation approach in achieving sustained release. 4. Loading Determination of Polyurea Microcapsules In studies relating

  2. Microfluidic assisted synthesis of multi-functional polycaprolactone microcapsules: incorporation of CdTe quantum dots, Fe3O4 superparamagnetic nanoparticles and tamoxifen anticancer drugs.

    PubMed

    Yang, C-H; Huang, K-S; Lin, Y-S; Lu, K; Tzeng, C-C; Wang, E-C; Lin, C-H; Hsu, W-Y; Chang, J-Y

    2009-04-07

    This paper demonstrates a proof-of-concept approach for encapsulating the anticancer drug tamoxifen, Fe3O4 nanoparticles (NPs) and CdTe quantum dots (QDs) into size-controlled polycaprolactone (PCL) microcapsules utilizing microfluidic emulsification, which combined magnetic targeting, fluorescence imaging and drug controlled release properties into one drug delivery system. Cross-linking the composite PCL microcapsules with poly(vinyl alcohol) (PVA) tailored their size, morphology, optical and magnetic properties and drug release behaviors. The flow conditions of the two immiscible solutions were adjusted in order to successfully generate various sizes of polymer droplets. The result showed superparamagnetic and fluorescent properties, and was used as a controlled drug release vehicle. The composite magnetic and fluorescent PCL microcapsules are potential candidates for a smart drug delivery system.

  3. Simultaneous Optimization of Multiple Response Variables for the Gelatin-chitosan Microcapsules Containing Angelica Essential Oil.

    PubMed

    Li, Qiang; Sun, Li-Jian; Gong, Xian-Feng; Wang, Yang; Zhao, Xue-Ling

    2017-01-01

    Angelica essential oil (AO), a major pharmacologically active component of Angelica sinensis (Oliv.) Diels, possesses hemogenesis, analgesic activities, and sedative effect. The application of AO in pharmaceutical systems had been limited because of its low oxidative stability. The AO-loaded gelatin-chitosan microcapsules with prevention from oxidation were developed and optimized using response surface methodology. The effects of formulation variables (pH at complex coacervation, gelatin concentration, and core/wall ratio) on multiple response variables (yield, encapsulation efficiency, antioxidation rate, percent of drug released in 1 h, and time to 85% drug release) were systemically investigated. A desirability function that combined these five response variables was constructed. All response variables investigated were found to be highly dependent on the formulation variables, with strong interactions observed between the formulation variables. It was found that optimum overall desirability of AO microcapsules could be obtained at pH 6.20, gelatin concentration 25.00%, and core/wall ratio 40.40%. The experimental values of the response variables highly agreed with the predicted values. The antioxidation rate of optimum formulation was approximately 8 times higher than that of AO. The in-vitro drug release from microcapsules was followed Higuchi model with super case-II transport mechanism.

  4. New polyurethane/docosane microcapsules as phase-change materials for thermal energy storage.

    PubMed

    Felix De Castro, Paula; Shchukin, Dmitry G

    2015-07-27

    Polyurethane microcapsules were prepared by mini-emulsion interfacial polymerization for encapsulation of phase-change material (n-docosane) for energy storage. Three steps were followed with the aim to optimize synthesis conditions of the microcapsules. First, polyurethane microcapsules based on silicone oil core as an inert template with different silicone oil/poly(ethylene glycol)/4,4'-diphenylmethane diisocyanate wt % ratio were synthesized. The surface morphology of the capsules was analyzed by scanning electronic microscopy (SEM) and the chemical nature of the shell was monitored by Fourier transform infrared spectroscopy (FT-IR). Capsules with the silicone oil/poly(ethylene glycol)/4,4'-diphenylmethane diisocyanate 10/20/20 wt % ratio showed the best morphological features and shell stability with average particle size about 4 μm, and were selected for the microencapsulation of the n-docosane. In the second stage, half of the composition of silicone oil was replaced with n-docosane and, finally, the whole silicone oil content was replaced with docosane following the same synthetic procedure used for silicone oil containing capsules. Thermal and cycling stability of the capsules were investigated by thermal gravimetric analysis (TGA) and the phase-change behavior was evaluated by differential scanning calorimetry (DSC). © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Fluorescence Detection of Microcapsule-Type Self-Healing, Based on Aggregation-Induced Emission.

    PubMed

    Song, Young Kyu; Kim, Beomjin; Lee, Tae Hee; Kim, Jin Chul; Nam, Joon Hyun; Noh, Seung Man; Park, Young Il

    2017-03-01

    An extrinsic self-healing coating system containing tetraphenylethylene (TPE) in microcapsules was monitored by measuring aggregation-induced emission (AIE). The core healing agent comprised of methacryloxypropyl-terminated polydimethylsiloxane, styrene, benzoin isobutyl ether, and TPE was encapsulated in a urea-formaldehyde shell. The photoluminescence of the healing agent in the microcapsules was measured that the blue emission intensity dramatically increased and the storage modulus also increased up to 10(5) Pa after the photocuring. These results suggested that this formulation might be useful as a self-healing material and as an indicator of the self-healing process due to the dramatic change in fluorescence during photocuring. To examine the ability of the healing agent to repair damage to a coating, a self-healing coating containing embedded microcapsules was scribed with a razor. As the healing process proceeded, blue light fluorescence emission was observed at the scribed regions. This observation suggested that self-healing could be monitored using the AIE fluorescence. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Facile microfluidic production of composite polymer core-shell microcapsules and crescent-shaped microparticles.

    PubMed

    Ekanem, Ekanem E; Zhang, Zilin; Vladisavljević, Goran T

    2017-07-15

    Core-shell microcapsules and crescent-shaped microparticles can be used as picolitre bioreactors for cell culture and microwells for cell trapping/immobilisation, respectively. Monodisperse polylactic acid (PLA) core-shell microcapsules with a diameter above 200μm, a shell thickness of 10μm, and 96% water entrapment efficiency were produced by solvent evaporation from microfluidically generated W/O/W emulsion drops with core-shell structure, and used to encapsulate Saccharomyces cerevisiae yeast cells in their aqueous cores. The morphological changes of the capsules stained with Nile red were studied over 14days under different osmotic pressure and pH gradients. The shell retained its integrity under isotonic conditions, but buckling and particle crumbling occurred in a hypertonic solution. When the capsules containing 5wt% aqueous Eudragit® S 100 solution in the core were incubated in 10(-4)M HCl solution, H(+) diffused through the PLA film into the core causing an ionic gelation of the inner phase and its phase separation into polymer-rich and water-rich regions, due to the transition of Eudragit from a hydrophilic to hydrophobic state. Crescent-shaped composite microparticles with Eudragit cores and PLA shells were fabricated by drying core-shell microcapsules with gelled cores, due to the collapse of PLA shells encompassing water-rich crescent regions. Copyright © 2017 Elsevier Inc. All rights reserved.

  7. 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.

  8. 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.

  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.

  10. 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.

  11. Therapeutic levels of human factor VIII in mice implanted with encapsulated cells: potential for gene therapy of haemophilia A.

    PubMed

    García-Martín, Carmen; Chuah, Marinee K L; Van Damme, An; Robinson, Kelly E; Vanzieleghem, Beatrijs; Saint-Remy, Jean-Marie; Gallardo, Dominique; Ofosu, Frederick A; Vandendriessche, Thierry; Hortelano, Gonzalo

    2002-01-01

    A gene therapy delivery system based on microcapsules enclosing recombinant cells engineered to secrete a therapeutic protein has been evaluated. The microcapsules are implanted intraperitoneally. In order to prevent cell immune rejection, cells are enclosed in non-antigenic biocompatible alginate microcapsules prior to their implantation into mice. It has been shown that encapsulated myoblasts can deliver therapeutic levels of Factor IX (FIX) in mice. The delivery of human Factor VIII (hFVIII) in mice using microcapsules was evaluated in this study. Mouse C2C12 myoblasts and canine MDCK epithelial kidney cells were transduced with MFG-FVIII (B-domain deleted) vector. Selected recombinant clones were enclosed in alginate microcapsules. Encapsulated recombinant clones were subsequently implanted intraperitoneally into C57BL/6 and immunodeficient SCID mice. Plasma of mice receiving C2C12 and encapsulated MDCK cells had transient therapeutic levels of FVIII in immunocompetent C57BL/6 mice (up to 20% and 7% of physiological levels, respectively). In addition, FVIII delivery in SCID mice was also transient, suggesting that a non-immune mechanism must have contributed to the decline of hFVIII in plasma. Quantitative RT-PCR analysis confirmed directly that the decline of hFVIII is due to a reduction in steady-state hFVIII mRNA, consistent with transcriptional repression. Furthermore, encapsulated cells retrieved from implanted mice were viable, but secreted FVIII ex vivo at three-fold lower levels than the pre-implantation levels. In addition, antibodies to hFVIII were detected in immunocompetent C57BL/6 mice. Implantable microcapsules can deliver therapeutic levels of FVIII in mice, suggesting the potential of this gene therapy approach for haemophilia A. The findings suggest vector down-regulation in vivo. Copyright 2002 John Wiley & Sons, Ltd.

  12. Impact of extra virgin olive oil and ethylenediaminetetraacetic acid (EDTA) on the oxidative stability of fish oil emulsions and spray-dried microcapsules stabilized by sugar beet pectin.

    PubMed

    Polavarapu, Sudheera; Oliver, Christine M; Ajlouni, Said; Augustin, Mary Ann

    2012-01-11

    The influence of EDTA on lipid oxidation in sugar beet pectin-stabilized oil-in-water emulsions (pH 6, 15% oil, wet basis), prepared from fish oil (FO) and fish oil-extra virgin olive oil (FO-EVOO) (1:1 w/w), as well as the spray-dried microcapsules (50% oil, dry basis) prepared from these emulsions, was investigated. Under accelerated conditions (80 °C, 5 bar oxygen pressure) the oxidative stability was significantly (P < 0.05) higher for FO and FO-EVOO formulated with EDTA, in comparison to corresponding emulsions and spray-dried microcapsules formulated without EDTA. The EDTA effect was greater in emulsions than in spray-dried microcapsules, with the greatest protective effect obtained in FO-EVOO emulsions. EDTA enhanced the oxidative stability of the spray-dried microcapsules during ambient storage (~25 °C, a(w) = 0.5), as demonstrated by their lower concentration of headspace volatile oxidation products, propanal and hexanal. These results show that the addition of EDTA is an effective strategy to maximize the oxidative stability of both FO emulsions and spray-dried microcapsules in which sugar beet pectin is used as the encapsulant material.

  13. 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

    2014-12-02

    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.

  14. The Influence of 1-Butanol and Trisodium Citrate Ion on Morphology and Chemical Properties of Chitosan-Based Microcapsules during Rigidification by Alkali Treatment

    PubMed Central

    Chatterjee, Sudipta; Salaün, Fabien; Campagne, Christine

    2014-01-01

    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

  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. 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.

  17. 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.

  18. Robust distribution network reconfiguration

    SciTech Connect

    Lee, Changhyeok; Liu, Cong; Mehrotra, Sanjay; Bie, Zhaohong

    2015-03-01

    We propose a two-stage robust optimization model for the distribution network reconfiguration problem with load uncertainty. The first-stage decision is to configure the radial distribution network and the second-stage decision is to find the optimal a/c power flow of the reconfigured network for given demand realization. We solve the two-stage robust model by using a column-and-constraint generation algorithm, where the master problem and subproblem are formulated as mixed-integer second-order cone programs. Computational results for 16, 33, 70, and 94-bus test cases are reported. We find that the configuration from the robust model does not compromise much the power loss under the nominal load scenario compared to the configuration from the deterministic model, yet it provides the reliability of the distribution system for all scenarios in the uncertainty set.

  19. 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.

  20. 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.

  1. 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.

  2. pH-Controlled Bacillus thuringiensis Cry1Ac Protoxin Loading and Release from Polyelectrolyte Microcapsules

    PubMed Central

    Yang, Wenhui; He, Kanglai; Zhang, Jie; Guo, Shuyuan

    2012-01-01

    Crystal proteins synthesized by Bacillus thuringiensis (Bt) have been used as biopesticides because of their toxicity to the insect larval hosts. To protect the proteins from environmental stress to extend their activity, we have developed a new microcapsule formulation. Poly (acrylic acid) (PAH) and poly (styrene sulfonate) (PSS) were fabricated through layer-by-layer self-assembly based on a CaCO3 core. Cry1Ac protoxins were loaded into microcapsules through layer-by-layer self-assembly at low pH, and the encapsulated product was stored in water at 4°C. Scanning electron microscopy (SEM) was used to observe the morphology of the capsules. To confirm the successful encapsulation, the loading results were observed with a confocal laser scattering microscope (CLSM), using fluorescein-labeled Cry1Ac protoxin (FITC-Cry1Ac). The protoxins were released from the capsule under the alkaline condition corresponding to the midgut of certain insects, a condition which seldom exists elsewhere in the environment. The following bioassay experiment demonstrated that the microcapsules with Cry1Ac protoxins displayed approximately equivalent insecticidal activity to the Asian corn borer compared with free Cry1Ac protoxins, and empty capsules proved to have no effect on insects. Further result also indicated that the formulation could keep stable under the condition of heat and desiccation. These results suggest that this formulation provides a promising methodology that protects protoxins from the environment and releases them specifically in the target insects’ midgut, which has shown potential as biopesticide in the field. PMID:23024810

  3. An Efficient, Recyclable, and Stable Immobilized Biocatalyst Based on Bioinspired Microcapsules-in-Hydrogel Scaffolds.

    PubMed

    Zhang, Shaohua; Jiang, Zhongyi; Shi, Jiafu; Wang, Xueyan; Han, Pingping; Qian, Weilun

    2016-09-28

    Design and preparation of high-performance immobilized biocatalysts with exquisite structures and elucidation of their profound structure-performance relationship are highly desired for green and sustainable biotransformation processes. Learning from nature has been recognized as a shortcut to achieve such an impressive goal. Loose connective tissue, which is composed of hierarchically organized cells by extracellular matrix (ECM) and is recognized as an efficient catalytic system to ensure the ordered proceeding of metabolism, may offer an ideal prototype for preparing immobilized biocatalysts with high catalytic activity, recyclability, and stability. Inspired by the hierarchical structure of loose connective tissue, we prepared an immobilized biocatalyst enabled by microcapsules-in-hydrogel (MCH) scaffolds via biomimetic mineralization in agarose hydrogel. In brief, the in situ synthesized hybrid microcapsules encapsulated with glucose oxidase (GOD) are hierarchically organized by the fibrous framework of agarose hydrogel, where the fibers are intercalated into the capsule wall. The as-prepared immobilized biocatalyst shows structure-dependent catalytic performance. The porous hydrogel permits free diffusion of glucose molecules (diffusion coefficient: ∼6 × 10(-6) cm(2) s(-1), close to that in water) and retains the enzyme activity as much as possible after immobilization (initial reaction rate: 1.5 × 10(-2) mM min(-1)). The monolithic macroscale of agarose hydrogel facilitates the easy recycling of the immobilized biocatalyst (only by using tweezers), which contributes to the nonactivity decline during the recycling test. The fiber-intercalating structure elevates the mechanical stability of the in situ synthesized hybrid microcapsules, which inhibits the leaching and enhances the stability of the encapsulated GOD, achieving immobilization efficiency of ∼95%. This study will, therefore, provide a generic method for the hierarchical organization of (bio

  4. Enhancement of survival of alginate-encapsulated Lactobacillus casei NCDC 298.

    PubMed

    Mandal, Surajit; Hati, Subrota; Puniya, Anil Kumar; Khamrui, Kaushik; Singh, Kishan

    2014-08-01

    Micro-encapsulation of hydrocolloids improves the survival of sensitive probiotic bacteria in the harsh conditions that prevail in foods and during gastrointestinal passage by segregating them from environments. Incorporation of additives in encapsulating hydrocolloids and coatings of microcapsules further improves the survival of the probiotics. In this study, the effect of incorporation of resistant-maize starch in alginate for micro-encapsulation and coating of microcapsules with poly-l-lysine, stearic acid and bees wax on the survival of encapsulated Lactobacillus casei NCDC 298 at pH 1.5, 2% high bile salt, 65 °C for 20 min and release of viable lactobacilli cells from the capsule matrix in simulated aqueous solutions of colonic pH were assessed. Addition of resistant maize starch (2%) improved the survival of encapsulated L. casei NCDC 298. Coating of microcapsules with poly-L-lysine did not further improve the protection of encapsulated cells from the harsh conditions; however, bees wax and stearic acid (2%) improved the survival under similar conditions. Incorporation of maize starch (2%) in alginate followed by coating of beads with stearic acid (2%) led to better protection and complete release of entrapped lactobacilli in simulated colonic pH solution was observed. Additional treatments improve the survival of alginate-encapsulated lactobacilli cells without hindering the release of active cells from the capsule matrix and hence, the resulting encapsulated probiotics can be exploited in the development of probiotic functional foods with better survival of sensitive probiotic organisms. © 2013 Society of Chemical Industry.

  5. 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.

  6. The influence of surface properties on uptake of oil into complex coacervate microcapsules.

    PubMed

    Rabiskova, M; Song, J; Opawale, F O; Burgess, D J

    1994-08-01

    A range of surfactants with different hydrophile-lipophile balance (HLB) values was selected to investigate the influence of interfacial properties on the uptake of oil droplets into complex coacervate microcapsules. The well characterized gelatin/acacia complex coacervate system was used in this study and the encapsulation of squalane, and oleic acid was investigated. The surfactants investigated were Span 85, Span 80, Span 40, egg yolk lecithin, and Tween 80. Combinations of surfactants were utilized to obtain intermediate HLB values. The percentage oil encapsulated was determined gravimetrically, based on the initial concentration and the amount extracted from the microcapsules. The aqueous interfacial tension values of the oils and oil/surfactant systems were measured using the Wilhelmy plate method. The interfacial properties were correlated to the percentage oil uptake by the coacervate phase. The relative hydrophobicity/lipophilicity of the oil influenced its uptake by complex coacervate droplets. The presence of surfactant affected oil uptake, depending on the HLB value of the surfactant or surfactant mixture. Uptake of squalane by the gelatin/acacia coacervates was found to be optimized by the addition of surfactants with HLB values in the range 2.5-6. The percentage uptake of oil decreased rapidly for systems prepared containing surfactants with HLB values outside this range. No correlation was observed between oil uptake by the coacervate phase and the interfacial tension of the oil and oil/surfactant systems with double-distilled deionized water.

  7. Nanoparticle assembled microcapsules for application as pH and ammonia sensor.

    PubMed

    Amali, Arlin Jose; Awwad, Nour H; Rana, Rohit Kumar; Patra, Digambara

    2011-12-05

    The encapsulation of molecular probes in a suitable nanostructured matrix can be exploited to alter their optical properties and robustness for fabricating efficient chemical sensors. Despite high sensitivity, simplicity, selectivity and cost effectiveness, the photo-destruction and photo-bleaching are the serious concerns while utilizing molecular probes. Herein we demonstrate that hydroxy pyrene trisulfonate (HPTS), a pH sensitive molecular probe, when encapsulated in a microcapsule structure prepared via the assembly of silica nanoparticles mediated by poly-L-lysine and trisodium citrate, provides a robust sensing material for pH sensing under the physiological conditions. The temporal evolution under continuous irradiation indicates that the fluorophore inside the silica microcapsule is extraordinarily photostable. The fluorescence intensity alternation at dual excitation facilitates for a ratiometic sensing of the pH, however, the fluorescence lifetime is insensitive to hydrogen ion concentration. The sensing scheme is found to be robust, fast and simple for the measurement of pH in the range 5.8-8.0, and can be successfully applied for the determination of ammonia in the concentration range 0-1.2 mM, which is important for aquatic life and the environment.

  8. Understanding the Mechanisms of Gold Shell Growth onto Polymer Microcapsules to Control Shell Thickness.

    PubMed

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

    2017-07-04

    Polymer microcapsules have been used commercially for decades, however they have an inherent flaw which renders them impractical as a carrier of small, volatile molecules. The porous nature of the polymer shell allows for diffusion of the encapsulated molecules into the bulk. The use of metal shells is an innovative way to prevent undesired loss of small molecules from the core of microcapsules, however it is important, particularly when using expensive metals to ensure that the resulting shell is as thin as possible. Here we investigate the fundamental mechanisms controlling the gold shell thickness when a fragrance oil is encapsulated in a poly(methyl methacrylate) shell. We consider the distribution of the nanoparticles on the capsule surface, and from quantification of the adsorbed nanoparticle (NP) density and resulting shell thickness, we propose mechanisms to describe the gold shell growth for systems with high and low NP surface coverage. We suggest from our observations that the gold grows to fill in the gaps between NPs. At low NP concentrations, thicker metal shells form. We postulate that this is due to the low NP density on the surface, forcing the gold clusters to grow larger before they meet the adjacent ones. Thus, to grow the thinnest possible shells a densely packed monolayer of platinum nanoparticles is required on the capsule surface. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. SIRTF Encapsulation

    NASA Image and Video Library

    2003-04-10

    The Space Infrared Telescope Facility (SIRTF) is ready for encapsulation. A fairing will be installed around the spacecraft to protect it during launch. SIRTF will obtain images and spectra by detecting the infrared energy, or heat, radiated by objects in space. Most of this infrared radiation is blocked by the Earth's atmosphere and cannot be observed from the ground. Consisting of an 0.85-meter telescope and three cryogenically cooled science instruments, SIRTF is one of NASA's largest infrared telescopes to be launched. SIRTF is currently scheduled for launch April 18 aboard a Delta II rocket from Launch Complex 17-B, Cape Canaveral Air Force Station.

  10. 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.

  11. Flow-driven Assembly of Microcapsule Towers

    NASA Astrophysics Data System (ADS)

    Shum, Henry; Balazs, Anna

    2016-11-01

    Large populations of the slime mold, Dictyostelium discoideum, are able to aggregate over a surface and collectively form a long, vertical stalk. Inspired by this biological behavior, we develop a synthetic mechanism for assembling tower-like structures using microcapsules as the building blocks. We accomplish this in simulations by generating a fluid flow field that draws microcapsules together along a surface and lifts them up at a central point. We considered a fluid flow generated by the local release of a chemical species from a patch on the surface. The concentration gradient of the diffusing chemical species causes radial diffusioosmotic flow along the solid surface toward the patch. Adhesive interactions keep the microcapsules attached to the surface as they are drawn together above the patch. To build a tower-like structure, some of the microcapsules must detach from the surface but remain attached to the rest of the cluster. The upward directed fluid flow above the patch then draws out the cluster into a tower shape. The final morphology of the aggregate structure depends on the flow field, the adhesive capsule-capsule and capsule-surface interaction strengths, and the sedimentation force on the capsules. Tuning these factors changes the structures that are produced.

  12. 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.

  13. 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.

  14. 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,…

  15. 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,…

  16. Inefficiency in macromolecular transport of SCS-based microcapsules affects viability of primary human mesenchymal stem cells but not of immortalized cells.

    PubMed

    Sanz-Nogués, Clara; Horan, Jason; Thompson, Kerry; Howard, Linda; Ryan, Gerard; Kassem, Moustapha; O'Brien, Timothy

    2015-11-01

    Microcapsules made of sodium cellulose sulphate (SCS) and poly-diallyl-dimethyl-ammonium chloride (pDADMAC) have been employed to encapsulate a wide range of established cell lines for several applications. However, little is known about the encapsulation of primary cells including human mesenchymal stem cells (hMSCs). Human MSCs are of interest in regenerative medicine applications due to pro-angiogenic, anti-inflammatory and immunomodulatory properties, which result from paracrine effects of this cell type. In the present work we have encapsulated primary hMSCs and hMSC-TERT immortalized cells and compared their behavior and in vitro angiogenic potential. We found that, although both cell types were able to secret angiogenic factors such as VEGF, there was a marked reduction of primary hMSC viability compared to hMSC-TERT cells when cultured in these microcapsules. Moreover, this applied to other primary cell cultures such as primary human fibroblasts but not to other cell lines such as human embryonic kidney 293 (HEK293) cells. We found that the microcapsule membrane had a molecular weight cut-off below a critical size, which caused impairment in the diffusion of essential nutrients and had a more detrimental effect on the viability of primary cell cultures compared to cell lines and immortalized cells.

  17. Micro-encapsulation of ozonated red pepper seed oil with antimicrobial activity and application to nonwoven fabric.

    PubMed

    Özyildiz, F; Karagönlü, S; Basal, G; Uzel, A; Bayraktar, O

    2013-03-01

    In recent years, functional fabrics possessing antimicrobial activity have drawn significant interest because antibiotic resistance is becoming widespread among pathogenic micro-organisms. The aim of this study was to produce microcapsules incorporating ozonated red pepper seed oil (ORPSO) with antimicrobial properties and apply them to nonwoven fabrics to prepare functional textiles. Red pepper seed oil (RPSO) was ozonated and micro-encapsulated via a complex coacervation method using gelatin (GE) and gum arabic (GA) as wall materials. While micro-encapsulation yield and oil loading decreased with increases in the amount of surfactant, the mean particle size increased. The antimicrobial activity of the oil was tested via the disc diffusion method. The microcapsules were also tested using the agar well method. While RPSO had no effect on the test micro-organisms, the ORPSO and microcapsules containing ORPSO were found to be active against the test micro-organisms. The microcapsules were then applied to nonwoven fabric using the padding method to produce a disposable functional textile. The microcapsule-impregnated functional fabrics provided a 5 log decrease in 1 h. It is therefore possible to functionalize nonwoven fabrics to have antimicrobial activity against antibiotic-resistant micro-organisms, using microcapsules containing ORPSO. This is the first report on the antimicrobial action of RPSO after ozonation process. These findings suggest that ozonated red pepper seed oil (ORPSO) may be a useful and effective antimicrobial agent against the micro-organisms with antibiotic resistance. Therefore, as a natural product, RPSO represents a sustainable alternative to the use of synthetic antimicrobial agents. To our knowledge, this is also the first time that ORPSO has been micro-encapsulated for the preparation of functional textile material with significant antimicrobial activity. © 2012 The Society for Applied Microbiology.

  18. 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.

  19. Synthesis of Stable Microcapsules from Trematode Eggshell Components

    DTIC Science & Technology

    1990-06-30

    NO Arlington, VA 22217-5000 61153N RR4106 11 TITLE (Include Security Classification) (u) Synthesis of Stable Microcapsules from Trematode Eggshell...Continue on reverse if necessary and identify by block number) The trematode Fasciola hepatica produces a unique protein eggshell or microcapsule the...proteins to produce a hard quinone tanned microcapsule with unusual properties. The focus of this project is to i) characterize the protein components

  20. Controlling the morphology of polyurea microcapsules using microfluidics.

    PubMed

    Polenz, Ingmar; Datta, Sujit S; Weitz, David A

    2014-11-11

    We use microfluidics to continuously produce monodisperse polyurea microcapsules (PUMCs) having either aqueous or nonaqueous cores. The microcapsule shells are formed by the reaction between an isocyanate, dissolved in oil, and an amine, dissolved in water, at the surface of oil-in-water or water-in-oil drops immediately as they are formed. Different microcapsule morphologies can be generated using our approach. The thickness of the microcapsule shell increases with an increase in the amine solubility in the oil; this finding provides a simple mechanism by which the PUMC shell thickness can be controlled.

  1. 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. Copyright © 2015 Elsevier Ltd. All rights reserved.

  2. Fluorescence lifetime and UV-Vis spectroscopy to evaluate the interactions between quercetin and its yeast microcapsule.

    PubMed

    Pham-Hoang, Bao-Ngoc; Winckler, Pascale; Waché, Yves

    2017-09-09

    Quercetin is a fragile bioactive compound. Several works have tried to preserve it by encapsulation but the form of encapsulation (mono- or supra-molecular structure, tautomeric form), though important for stability and bioavailability, remains unknown. The present work aims at developing a fluorescence lifetime technique to evaluate the structure of quercetin during encapsulation in a vector capsule that has already proven efficiency, yeast cells. Molecular stabilization was observed during a four-month storage period. The time-correlated single-photon counting (TCSPC) technique was used to evaluate the interaction between quercetin molecules and the yeast capsule. The various tautomeric forms, as identified by UV-Vis spectroscopy, resulted in various lifetimes in TCSPC, although they varied also with the buffer environment. Quercetin in buffer exhibited a three-to-four longer long time after 24 h (changing from 6-7 to 18-23 ns), suggesting an aggregation of molecules. In yeast microcapsules, the long-time population exhibited a longer lifetime (around 27 ns) from the beginning and concerned about 20% of molecules compared to dispersed quercetin. This shows that lifetime analysis can show the monomolecular instability of quercetin in buffer and the presence of interactions between quercetin molecules and their microcapsules. This article is protected by copyright. All rights reserved.

  3. Robust microfluidic encapsulation of cholesteric liquid crystals toward photonic ink capsules.

    PubMed

    Lee, Sang Seok; Kim, Bomi; Kim, Su Kyung; Won, Jong Chan; Kim, Yun Ho; Kim, Shin-Hyun

    2015-01-27

    Robust photonic microcapsules are created by microfluidic encapsulation of cholesteric liquid crystals with a hydrogel membrane. The membrane encloses the cholesteric core without leakage in water and the core exhibits pronounced structural colors. The photonic ink capsules, which have a precisely controlled bandgap position and size, provide new opportunities in colorimetric micro-thermometers and optoelectric applications. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Optimal Reconfiguration of Tetrahedral Formations

    NASA Technical Reports Server (NTRS)

    Huntington, Geoffrey; Rao, Anil V.; Hughes, Steven P.

    2004-01-01

    The problem of minimum-fuel formation reconfiguration for the Magnetospheric Multi-Scale (MMS) mission is studied. This reconfiguration trajectory optimization problem can be posed as a nonlinear optimal control problem. In this research, this optimal control problem is solved using a spectral collocation method called the Gauss pseudospectral method. The objective of this research is to provide highly accurate minimum-fuel solutions to the MMS formation reconfiguration problem and to gain insight into the underlying structure of fuel-optimal trajectories.

  5. Reconfigurable Drive Current System

    NASA Technical Reports Server (NTRS)

    Alhorn, Dean C. (Inventor); Dutton, Kenneth R. (Inventor); Howard, David E. (Inventor); Smith, Dennis A. (Inventor)

    2017-01-01

    A reconfigurable drive current system includes drive stages, each of which includes a high-side transistor and a low-side transistor in a totem pole configuration. A current monitor is coupled to an output of each drive stage. Input channels are provided to receive input signals. A processor is coupled to the input channels and to each current monitor for generating at least one drive signal using at least one of the input signals and current measured by at least one of the current monitors. A pulse width modulation generator is coupled to the processor and each drive stage for varying the drive signals as a function of time prior to being supplied to at least one of the drive stages.

  6. 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.

  7. Reconfigurable pipelined processor

    SciTech Connect

    Saccardi, R.J.

    1989-09-19

    This patent describes a reconfigurable pipelined processor for processing data. It comprises: a plurality of memory devices for storing bits of data; a plurality of arithmetic units for performing arithmetic functions with the data; cross bar means for connecting the memory devices with the arithmetic units for transferring data therebetween; at least one counter connected with the cross bar means for providing a source of addresses to the memory devices; at least one variable tick delay device connected with each of the memory devices and arithmetic units; and means for providing control bits to the variable tick delay device for variably controlling the input and output operations thereof to selectively delay the memory devices and arithmetic units to align the data for processing in a selected sequence.

  8. Nonlinear deformations of microcapsules in elongation flow

    NASA Astrophysics Data System (ADS)

    Deschamps, Julien; de Loubens, Clément; Boedec, Gwenn; Georgelin, Marc; Leonetti, Marc; Soft Matter; Biophysics Group Team

    2014-11-01

    Soft microcapsules are drops bounded by a thin elastic shell made of cross-linked proteins. They have numerous applications for drug delivery in bioengineering, pharmaceutics and medicine, where their mechanical stability and their dynamics under flow are crucial. They can also be used as red blood cells models. Here, we investigate the mechanical behaviour of microcapsules made of albumine in strong elongational flow, up to a stretching of 180% just before breaking. The set-up allows us to visualize the deformed shape in the two perpendicular main fields of view, to manage high capillary number and to manipulate soft microcapsules. The steady-state shape of a capsule in the planar elongational flow is non-axisymmetric. In each cross section, the shape is an ellipse but with different small axis which vary in opposite sense with the stretching. Whatever the degree of cross-linking and the size of the capsules, the deformations followed the same master-curve. Comparisons between numerical predictions and experimental results permit to conclude unambiguously that the more properly strain-energy model of membrane is the generalized Hooke model.

  9. 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.

  10. 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

    2012-02-16

    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.

  11. Complex reconfiguration of DNA nanostructures.

    PubMed

    Wei, Bryan; Ong, Luvena L; Chen, Jeffrey; Jaffe, Alexander S; Yin, Peng

    2014-07-14

    Nucleic acids have been used to create diverse synthetic structural and dynamic systems. Toehold-mediated strand displacement has enabled the construction of sophisticated circuits, motors, and molecular computers. Yet it remains challenging to demonstrate complex structural reconfiguration in which a structure changes from a starting shape to another arbitrarily prescribed shape. To address this challenge, we have developed a general structural-reconfiguration method that utilizes the modularly interconnected architecture of single-stranded DNA tile and brick structures. The removal of one component strand reveals a newly exposed toehold on a neighboring strand, thus enabling us to remove regions of connected component strands without the need to modify the strands with predesigned external toeholds. By using this method, we reconfigured a two-dimensional rectangular DNA canvas into diverse prescribed shapes. We also used this method to reconfigure a three-dimensional DNA cuboid. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Process for Preparing Microcapsules Having Gelatin Walls Crosslinked with Quinone.

    DTIC Science & Technology

    A process for conveniently producing microcapsules containing a gelatin wall crosslinked with quinone and a core of an active compound such as a...provides microcapsules of excellent strength, storage stability, and resistance to aqueous exposure, such that the rate of release of the fouling reducing agent can be controlled with precision. jg

  13. 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.

  14. Insulin-loaded microcapsules for in vivo delivery.

    PubMed

    Kim, Byung Soo; Oh, Jae Min; Hyun, Hoon; Kim, Kyung Sook; Lee, Sang Hyo; Kim, Yu Han; Park, Kinam; Lee, Hai Bang; Kim, Moon Suk

    2009-01-01

    Microencapsulation of insulin has been difficult, due to the high sensitivity of insulin to the harsh conditions that can occur during the microencapsulation process. We have developed a method of preparing insulin-loaded microcapsules by using a monoaxial ultrasonic atomizer to form microdroplets of insulin in aqueous solution surrounded by poly(lactic-co-glycolic acid) (PLGA) solution. Administration of these insulin-loaded microcapsules to type 1 diabetic rats maintained plasma insulin concentrations for 30 days, due to the sustained insulin release properties of the microcapsules. In contrast, plasma insulin concentrations after subcutaneous injection of insulin solution reached near zero levels within 2 days. Insulin solution showed only an immediate pharmacological effect, with no reduction of glycemia after 3 days, whereas insulin-loaded microcapsules maintained blood glucose levels at 100-200 mg/dL for 55 days. Molecular imaging using fluorescein isothiocyanate (FITC)-insulin-loaded microcapsules showed in vivo sustained release of the FITC-insulin in microcapsules. Using insulin-loaded microcapsules, we observed inflammation only immediately after injection, indicating that the rats adapted to long-term insulin release. In conclusion, insulin-loaded microcapsules may reduce nonrepetitive insulin administration and show sustained pharmacological performance.

  15. Preparation of microcapsules with multi-layers structure stabilized by chitosan and sodium dodecyl sulfate.

    PubMed

    Chatterjee, Sudipta; Salaün, Fabien; Campagne, Christine; Vaupre, Suzy; Beirão, Alexandre

    2012-10-01

    The microcapsules with oil core and multi-layers shell were developed from poly-cationic chitosan (CS) and anionic SDS in multistep electrostatic layer by layer deposition technique combined with oil in water emulsification process. The net charge of microcapsules determined by zeta potential indicated that microcapsules are highly positive charged because of poly-cationic nature of CS, and charge neutralization of microcapsules occurred after alkali treatment. The granulometry measurement showed increase in average diameter of microcapsules by alkali treatment suggesting swelling or formation of small aggregates. The morphology analysis of microcapsules by optical microscopy corroborated the results of granulometry, and diameter of microcapsules was found to be decreased in multistep process due to tight packing of layers in outer shell of microcapsules. The alkali treatment of microcapsules to solidify outer shell was optimized with 0.02 N NaOH to reduce microcapsules aggregation and gel formation by CS chains as found in optical micrographs.

  16. 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.

  17. A laboratory-scale device for the straightforward production of uniform, small sized cell microcapsules with long-term cell viability.

    PubMed

    Kontturi, Leena-Stiina; Yliperttula, Marjo; Toivanen, Pyry; Määttä, Antti; Määttä, Ann-Marie; Urtti, Arto

    2011-06-30

    Microencapsulated and genetically engineered cells may be used for prolonged delivery of therapeutically active proteins. The objective of this study was to develop a simple, inexpensive and flexible laboratory-scale device for the production of cell microcapsules, especially capsules of small diameter (<300 μm). Many microencapsulation devices are expensive, difficult to assemble and to use, and often more suitable for large-scale experiments. However, the simplicity and low price of the encapsulation system should not limit the quality of capsules and reproducibility of the process: for successful in vitro and in vivo experiments it is important to be able to produce uniform, spherical microcapsules without deformities with high reproducibility. In addition, an advantage of the present procedure compared to other similar, co-axial laminar gas flow systems is the possibility to produce also small microcapsules, less than 200 μm in diameter, with narrow size distribution. First, design, optimization and reproducibility testing of this custom-built device were carried out. Second, microencapsulated retinal pigment epithelial cells (ARPE-19) capable of secreting soluble vascular endothelial growth factor receptor 1 (sVEGFR1) were engineered. The cells remained viable in alginate-poly-L-lysine-alginate microcapsules and secreted sVEGFR1 for prolonged periods.

  18. 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.

  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. 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.

  1. Enhanced thermal properties with graphene oxide in the urea-formaldehyde microcapsules containing paraffin PCMs.

    PubMed

    Qiao, Zhen; Mao, Jian

    2017-02-01

    In this study, compact urea-formaldehyde microcapsules containing paraffin (UFP) phase change materials (PCMs) were prepared via in situ polymerisation. The thermal conductivity of the PCMs was enhanced without influencing their enthalpy by adding graphene oxide (GO). Two modification methods were investigated: One in which GO is added to the inside of microcapsules, defined as "paraffin/GO@UF composite"; and another in which GO is coated onto the surface of shell, defined as "paraffin@UF/GO composite". The GO sheets were visible in scanning electron microscope (SEM) images of paraffin@UF/GO composite. The thermal conductivity was 0.2236 ± 0.0003 W/(m·K) for UFP particles, was 0.2517 ± 0.0003 W/(m·K) for the paraffin/GO@UF composite (10 wt%), and was 1.0670 ± 0.0020 W/(m·K) for paraffin@UF/GO composite (10 wt%), respectively. The encapsulation efficiency of all samples exceeded 80% (w/w) and all samples exhibited favourable thermal stability and reliability. The IR emissivity of paraffin@UF/GO was lower than that of paraffin/GO@UF when the same GO amount was added to the composite.

  2. Formation of titanium dioxide core-shell microcapsules through a binary-phase spray technique.

    PubMed

    Bergek, Jonatan; Elgh, Björn; Palmqvist, Anders E C; Nordstierna, Lars

    2017-09-13

    Core-shell microcapsules consisting of a titanium dioxide shell and a hydrophobic solvent core have been prepared with diameters of a few micrometers and a narrow size distribution using a simple and fast airbrush technique. These microcapsules were prepared at room temperature in a single-step process in which an oil with a dissolved titanium alkoxide precursor was forced together with an aqueous solution, containing a surface-active polymer, through a narrow spray nozzle using a nitrogen gas propellant. Several different parameters of chemical, physical, and processing origin were investigated to find an optimal recipe. Two different alkanes, one ketone, and four alcohols were tested and evaluated as core materials, alone or together with the antifungal biocide 2-n-octyl-4-isothiazolin-3-one (OIT). Long-chain alcohols were found suitable as core oil due to their low solubility in water and surface activity. The addition of the surface-active polymers in the water phase was important in aiding the formation and stabilization of the titanium dioxide shell. An impressive loading of 50 wt% of the semi-hydrophobic OIT was possible to encapsulate using this simple and applicable procedure.

  3. 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.

  4. 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

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

    PubMed

    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.

  6. 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.

  7. 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.

  8. 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.

  9. 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

  10. Encapsulated islets for diabetes therapy: history, current progress, and critical issues requiring solution.

    PubMed

    Scharp, David W; Marchetti, Piero

    2014-04-01

    Insulin therapy became a reality in 1921 dramatically saving lives of people with diabetes, but not protecting them from long-term complications. Clinically successful free islet implants began in 1989 but require life long immunosuppression. Several encapsulated islet approaches have been ongoing for over 30 years without defining a clinically relevant product. Macro-devices encapsulating islet mass in a single device have shown long-term success in large animals but human trials have been limited by critical challenges. Micro-capsules using alginate or similar hydrogels encapsulate individual islets with many hundreds of promising rodent results published, but a low incidence of successful translation to large animal and human results. Reduction of encapsulated islet mass for clinical transplantation is in progress. This review covers the status of both early and current studies including the presentation of corporate efforts involved. It concludes by defining the critical items requiring solution to enable a successful clinical diabetes therapy.

  11. Encapsulation of living E. coli cells in hollow polymer microspheres of highly defined size.

    PubMed

    Flemke, Jennifer; Maywald, Matthias; Sieber, Volker

    2013-01-14

    Here, we report the preparation and characterization of hollow polymer microspheres based on the preprecipitation of porous calcium carbonate cores with an average size of 5 μm and their use for encapsulation of living microorganisms. The microspheres filled with individual living E. coli cells were prepared by layer-by-layer (LbL) deposition of different polyelectrolytes and proteins onto the porous calcium carbonate cores leading to the formation of matrix-like complexes of the compounds followed by calcium carbonate core dissolution using EDTA. Both the influence of the encapsulation process as well as of the used polyelectrolytes on the survival rate of the cells were determined by confocal laser scanning microscopy (CLSM) and microtiter plate fluorescence tests. After the encapsulation process ~40% of the cells were alive. Cultivation tests indicated that the lag phase of cells treated with polyelectrolytes increases and the encapsulated E. coli cells were able to produce green fluorescent protein inside the microcapsules.

  12. Fault tolerance through reconfiguration in VLSI and WSI arrays

    SciTech Connect

    Negrini, R.; Sami, M.G.; Stefanelli, R. )

    1989-01-01

    This book discusses the research in fault tolerance. The authors focus in particular on reconfiguration techniques and present their results in the reconfiguration of processing arrays. Contents include: Introduction; Typical Processing Arrays; Failure Mechanisms and Fault Models; Basic Problems of Fault-Tolerance Through Array Configuration; Technologies Supporting Reconfiguration; Testing; Reconfiguration: An Introduction; The Diogenes Approach; Reconfiguration for Linear Arrays; Graph-Theoretical Approaches to Reconfiguration; Local Reconfiguration; Global Reconfiguration Techniques: Row/Column Elimination; Global Mapping: Index Mapping Reconfiguration Techniques; Reconfiguration Based on Request-Acknowledge Local Protocols; Reconfiguration of Multiple-Pipeline Structures; Some Extensions Toward Time-Redundancy; Appendix: Reliability Prediction of Arrays.

  13. Improved viability of Lactobacillus acidophilus NRRL-B 4495 during freeze-drying in whey protein-pullulan microcapsules.

    PubMed

    Çabuk, Burcu; Harsa, Şebnem Tellioglu

    2015-01-01

    In this research, pullulan was incorporated in protein-based encapsulation matrix in order to assess its cryoprotective effect on the viability of freeze-dried (FD) probiotic Lactobacillus acidophilus NRRL-B 4495. This study demonstrated that pullulan in encapsulation matrix resulted in a 90.4% survival rate as compared to 88.1% for whey protein (WPI) encapsulated cells. The protective effects of pullulan on the survival of FD-encapsulated cells in gastrointestinal conditions were compared. FD WPI-pullulan capsules retained higher survived cell numbers (7.10 log CFU/g) than those of FD WPI capsules (6.03 log CFU/g) after simulated gastric juice exposure. Additionally, use of pullulan resulted in an increased viability after bile exposure. FD-free bacteria exhibited 2.18 log CFU/g reduction, while FD WPI and FD WPI-pullulan encapsulated bacteria showed 0.95 and 0.49 log CFU/g reduction after 24 h exposure to bile solution, respectively. Morphology of the FD microcapsules was visualized by scanning electron microscopy.

  14. 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. Copyright © 2016 Elsevier B.V. All rights reserved.

  15. A novel encapsulation of N,N-diethyl-3-methylbenzamide (DEET) favorably modifies skin absorption while maintaining effective evaporation rates.

    PubMed

    Karr, Jennifer I; Speaker, Tycho J; Kasting, Gerald B

    2012-06-28

    N,N-diethyl-3-methylbenzamide (DEET) is popular insect repellent which is considered safe and effective, yet is subject to considerable skin absorption. Skin absorption decreases effective repellency since less DEET is available for evaporation. We have investigated the extent to which DEET skin absorption can be reduced and evaporation sustained through encapsulation. DEET permeation through human skin in vitro was measured for an ethanolic solution standard and for two novel topical controlled-release formulations in which the DEET active material was temporarily sequestered within a permeable, charged-film microcapsule. Evaporation measurements were gathered using Tenax TA cartridges and a sampling pump drawing air over the skin. Three formulations were studied: a previously reported microcapsule formulation (Formulation A); a newly-developed microcapsule formulation (Formulation B); and a non-encapsulated ethanol control solution. Formulation B led to a 30% reduction in DEET permeation versus control. The two microcapsule DEET formulations exhibited 36-40% higher cumulative evaporation from the skin than did the control. The vapor trapping measurements in vitro show that Formulation B provided more than 48h of effective evaporation rate for repellency, while Formulation A provided less than 35h and the ethanol control less than 15h. This establishes a technical advantage for the controlled-release approach.

  16. Encapsulation of Volatile Compounds in Silk Microparticles.

    PubMed

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

    2015-07-01

    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.

  17. 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

  18. Experimental Study on Cementitious Composites Embedded with Organic Microcapsules

    PubMed Central

    Wang, Xianfeng; Xing, Feng; Zhang, Ming; Han, Ningxu; Qian, Zhiwei

    2013-01-01

    The recovery behavior for strength and impermeability of cementitious composites embedded with organic microcapsules was investigated in this study. Mortar specimens were formed by mixing the organic microcapsules and a catalyst with cement and sand. The mechanical behaviors of flexural and compression strength were tested. The results showed that strength could increase by up to nine percent with the addition of a small amount of microcapsules and then decrease with an increasing amount of microcapsules. An orthogonal test for investigating the strength recovery rate was designed and implemented for bending and compression using the factors of water/cement ratio, amount of microcapsules, and preloading rate. It is shown that the amount of microcapsules plays a key role in the strength recovery rate. Chloride ion permeability tests were also carried out to investigate the recovery rate and healing effect. The initial damage was obtained by subjecting the specimens to compression. Both the recovery rate and the healing effect were nearly proportional to the amount of microcapsules. The obtained cementitious composites can be seen as self-healing owing to their recovery behavior for both strength and permeability. PMID:28788318

  19. Electrophoretic properties of sulfamethoxazole microcapsules and gelatin-acacia coacervates.

    PubMed

    Takenaka, H; Kawashima, Y; Lin, S Y

    1981-03-01

    The electrophoretic properties of sulfamethoxazole microcapsules and the coacervates prepared by gelatin-acacia coacervation were investigated. The effects of the parameters in the microcapsule preparation, such as the coacervation pH, amount of formaldehyde used for hardening, and drying method of the coacervates, on the zeta-potential of the resultant microcapsules were clarified. The Büchner effect was observed in coacervates in an electric field, which indicated that the coacervate wall was flexible. The zeta-potential versus pH curves of the coacervates appeared on the upper side of the plain sulfamethoxazole, while those of the microcapsules dried conventionally shifted to the lower side due to the denaturation of the gelatin in the microcapsule wall, which occurred during drying. Spray drying increased the denaturation of gelatin, which imparted a negative charge to the spray-dried microcapsules. Formalization of the coacervates refined the electrophoretic behavior of the microcapsules, depending on the amount of formaldehyde used. The zeta-potential of the plain sulfamethoxazole also was measured in the simulated coacervation solution to analyze the mechanism of coacervation electrophoretically.

  20. Experimental Study on Cementitious Composites Embedded with Organic Microcapsules.

    PubMed

    Wang, Xianfeng; Xing, Feng; Zhang, Ming; Han, Ningxu; Qian, Zhiwei

    2013-09-16

    The recovery behavior for strength and impermeability of cementitious composites embedded with organic microcapsules was investigated in this study. Mortar specimens were formed by mixing the organic microcapsules and a catalyst with cement and sand. The mechanical behaviors of flexural and compression strength were tested. The results showed that strength could increase by up to nine percent with the addition of a small amount of microcapsules and then decrease with an increasing amount of microcapsules. An orthogonal test for investigating the strength recovery rate was designed and implemented for bending and compression using the factors of water/cement ratio, amount of microcapsules, and preloading rate. It is shown that the amount of microcapsules plays a key role in the strength recovery rate. Chloride ion permeability tests were also carried out to investigate the recovery rate and healing effect. The initial damage was obtained by subjecting the specimens to compression. Both the recovery rate and the healing effect were nearly proportional to the amount of microcapsules. The obtained cementitious composites can be seen as self-healing owing to their recovery behavior for both strength and permeability.

  1. Preserving catalytic activity and enhancing biochemical stability of the therapeutic enzyme asparaginase by biocompatible multilayered polyelectrolyte microcapsules.

    PubMed

    Karamitros, Christos S; Yashchenok, Alexey M; Möhwald, Helmuth; Skirtach, Andre G; Konrad, Manfred

    2013-12-09

    The present study focuses on the formation of microcapsules containing catalytically active L-asparaginase (L-ASNase), a protein drug of high value in antileukemic therapy. We make use of the layer-by-layer (LbL) technique to coat protein-loaded calcium carbonate (CaCO3) particles with two or three poly dextran/poly-L-arginine-based bilayers. To achieve high loading efficiency, the CaCO3 template was generated by coprecipitation with the enzyme. After assembly of the polymer shell, the CaCO3 core material was dissolved under mild conditions by dialysis against 20 mM EDTA. Biochemical stability of the encapsulated L-asparaginase was analyzed by treating the capsules with the proteases trypsin and thrombin, which are known to degrade and inactivate the enzyme during leukemia treatment, allowing us to test for resistance against proteolysis by physiologically relevant proteases through measurement of residual l-asparaginase activities. In addition, the thermal stability, the stability at the physiological temperature, and the long-term storage stability of the encapsulated enzyme were investigated. We show that encapsulation of l-asparaginase remarkably improves both proteolytic resistance and thermal inactivation at 37 °C, which could considerably prolong the enzyme's in vivo half-life during application in acute lymphoblastic leukemia (ALL). Importantly, the use of low EDTA concentrations for the dissolution of CaCO3 by dialysis could be a general approach in cases where the activity of sensitive biomacromolecules is inhibited, or even irreversibly damaged, when standard protocols for fabrication of such LbL microcapsules are used. Encapsulated and free enzyme showed similar efficacies in driving leukemic cells to apoptosis.

  2. Trimodal Gadolinium-Gold Microcapsules Containing Pancreatic Islet Cells Restore Normoglycemia in Diabetic Mice and Can Be Tracked by Using US, CT, and Positive-Contrast MR Imaging

    PubMed Central

    Arifin, Dian R.; Long, Christopher M.; Gilad, Assaf A.; Alric, Christophe; Roux, Stéphane; Tillement, Olivier; Link, Thomas W.; Arepally, Aravind; Bulte, Jeff W. M.

    2011-01-01

    Purpose: To develop microcapsules that immunoprotect pancreatic islet cells for treatment of type I diabetes and enable multimodal cellular imaging of transplanted islet cells. Materials and Methods: All animal experiments were approved by the institutional animal care and use committee. Gold nanoparticles functionalized with DTDTPA (dithiolated diethylenetriaminepentaacetic acid):gadolinium chelates (GG) were coencapsulated with pancreatic islet cells by using protamine sulfate as a clinical-grade alginate cross linker. Conventional poly-l-lysine–cross-linked microcapsules and unencapsulated islets were included as controls. The viability and glucose responsiveness of islet cells were assessed in vitro, and in vivo insulin (C-peptide) secretion was monitored for 6 weeks in (streptozotocin-induced) diabetic mice with (n = 7) or without (n = 8) intraabdominally engrafted islet cells. Five nondiabetic mice were included as controls. Differences between samples were calculated by using a nonparametric Wilcoxon Mann-Whitney method. To adjust for multiple comparisons, a significance level of P < .01 was chosen. Generalized estimating equations were used to model cell function over time. Three mice with engrafted capsules were imaged in vivo with high-field-strength (9.4-T) magnetic resonance (MR) imaging, micro–computed tomography (CT), and 40-MHz ultrasonography (US). Results: Encapsulated human pancreatic islets were functional in vitro for at least 2 weeks after encapsulation. Blood glucose levels in the diabetic mice transplanted with GG-labeled encapsulated mouse βTC6 insulinoma cells returned to normal within 1 week after transplantation, and normoglycemia was sustained for at least 6 weeks without the use of immunosuppressive drugs. GG microcapsules could be readily visualized with positive-contrast high-field-strength MR imaging, micro-CT, and US both in vitro and in vivo. Conclusion: Cell encapsulation with GG provides a means of trimodal noninvasive

  3. 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.

  4. Reconfigurable virtual electrowetting channels.

    PubMed

    Banerjee, Ananda; Kreit, Eric; Liu, Yuguang; Heikenfeld, Jason; Papautsky, Ian

    2012-02-21

    Lab-on-a-chip systems rely on several microfluidic paradigms. The first uses a fixed layout of continuous microfluidic channels. Such lab-on-a-chip systems are almost always application specific and far from a true "laboratory." The second involves electrowetting droplet movement (digital microfluidics), and allows two-dimensional computer control of fluidic transport and mixing. The merging of the two paradigms in the form of programmable electrowetting channels takes advantage of both the "continuous" functionality of rigid channels based on which a large number of applications have been developed to date and the "programmable" functionality of digital microfluidics that permits electrical control of on-chip functions. In this work, we demonstrate for the first time programmable formation of virtual microfluidic channels and their continuous operation with pressure driven flows using an electrowetting platform. Experimental, theoretical, and numerical analyses of virtual channel formation with biologically relevant electrolyte solutions and electrically-programmable reconfiguration are presented. We demonstrate that the "wall-less" virtual channels can be formed reliably and rapidly, with propagation rates of 3.5-3.8 mm s(-1). Pressure driven transport in these virtual channels at flow rates up to 100 μL min(-1) is achievable without distortion of the channel shape. We further demonstrate that these virtual channels can be switched on-demand between multiple inputs and outputs. Ultimately, we envision a platform that would provide rapid prototyping of microfluidic concepts and would be capable of a vast library of functions and benefitting applications from clinical diagnostics in resource-limited environments to rapid system prototyping to high throughput pharmaceutical applications.

  5. Synthesis of Stable Microcapsules from Trematode Eggshell Components.

    DTIC Science & Technology

    1988-04-29

    8217 Arlington, VA 22217-5000 61153N RR4106 71,E ’Include Security Classification) (u) Synthesis of Stable Microcapsules from Trematode Eggshell Components 12...necessary and Identify by block number) 3RO~P SUB-P~iA Microcapsule , Dopa-proteins, trematode, crosslinks, eggshell 79 ABSTRAC7 ,Continue an reverse If...All other editions are obsolete. S ,.O 0 V po r t -A’X I T!L~-r ....7 KIT X - ~.W.:,iili Synthesis of Stable Microcapsules from Trematode Eggshell

  6. 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.

  7. Multilayered polyelectrolyte microcapsules: interaction with the enzyme cytochrome C oxidase.

    PubMed

    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.

  8. Image processing using reconfigurable FPGAs

    NASA Astrophysics Data System (ADS)

    Ferguson, Lee

    1996-10-01

    The use of reconfigurable field-programmable gate arrays (FPGAs) for imaging applications show considerable promise to fill the gap that often occurs when digital signal processor chips fail to meet performance specifications. Single chip DSPs do not have the overall performance to meet the needs of many imaging applications, particularly in real-time designs. Using multiple DSPs to boost performance often presents major design challenges in maintaining data alignment and process synchronization. These challenges can impose serious cost, power consumption and board space penalties. Image processing requires manipulating massive amounts of data at high-speed. Although DSP chips can process data at high-speeds, their architectures can inhibit overall system performance in real-time imaging. The rate of operations can be increased when they are performed in dedicated hardware, such as special-purpose imaging devices and FPGAs, which provides the horsepower necessary to implement real-time image processing products successfully and cost-effectively. For many fixed applications, non-SRAM- based (antifuse or flash-based) FPGAs provide the raw speed to accomplish standard high-speed functions. However, in applications where algorithms are continuously changing and compute operations must be modified, only SRAM-based FPGAs give enough flexibility. The addition of reconfigurable FPGAs as a flexible hardware facility enables DSP chips to perform optimally. The benefits primarily stem from optimizing the hardware for the algorithms or the use of reconfigurable hardware to enhance the product architecture. And with SRAM-based FPGAs that are capable of partial dynamic reconfiguration, such as the Cache-Logic FPGAs from Atmel, continuous modification of data and logic is not only possible, it is practical as well. First we review the particular demands of image processing. Then we present various applications and discuss strategies for exploiting the capabilities of

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. Preparation, characterisation and thermal properties of calcium alginate/n-nonadecane microcapsules fabricated by electro-coextrusion for thermo-regulating textiles.

    PubMed

    Kamali Moghaddam, Meghdad; Mortazavi, Sayed Majid

    2015-01-01

    The objective of this study is to develop a new technique for producing a phase change material (PCM) loaded biopolymer capsule for thermo-regulating textiles. Electro-coextrusion process fabricated a series of microencapsulated phase change material (MEPCM) based on n-nonadecane core and alginate shell. The influence of the flow rate ratio of the shell/core on the formation, encapsulation efficiency and thermal behaviour of a microencapsulated PCM has been investigated. The MEPCM was characterised using optical microscopy and differential scanning calorimetry (DCS). The size and the encapsulation efficiency of a capsule decreased as the flow rate ratio of the shell/core increased. The PCM microcapsules contained 56-84% n-nonadecane and the size range from 200 to 400 µm, as evaluated by DSC and optical microscopy, respectively. The experimental results show that the electro-coextrusion method has a potential technology for the encapsulation of PCMs for thermal storage.

  14. 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

  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. © 2015 Institute of Food Technologists®

  16. Evaluation of compressibility of pentaestergum coated aspirin microcapsules.

    PubMed

    Pathak, Y V; Dorle, A K

    1989-01-01

    We have earlier reported the usefulness of the pentaerythritol rosin ester (pentaestergum) as a coating material, its dissolution kinetics and in vivo release studies in dogs. The present communication deals with the compressibility of the pentaestergum-coated aspirin microcapsules. The microcapsules were prepared by the pan-coating method described earlier. These were compressed into the tablets using a single punch machine. The tablets were evaluated for hardness, friability loss, disintegration time and dissolution studies. The results showed that there were significant differences in the release characteristics from the microcapsules and the compressed tablets. The effect of 5 per cent starch as a disintegrating agent in the tablet formulation was also studied. The results showed that the tablets can be a suitable dosage form for pentaestergum-coated microcapsules to give a delayed drug release.

  17. 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.

  18. 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

  19. Characterization of polysulfone and polysulfone/vanillin microcapsules by 1H NMR spectroscopy, solid-state 13C CP/MAS-NMR spectroscopy, and N2 adsorption-desorption analyses.

    PubMed

    Peña, Brisa; de Ménorval, Louis-Charles; Garcia-Valls, Ricard; Gumí, Tània

    2011-11-01

    Textile detergent and softener industries have incorporated perfume microencapsulation technology to improve their products. Perfume encapsulation allows perfume protection until use and provides a long-lasting fragrance release. But, certain industrial microcapsules show low encapsulation capacity and low material stability. Polysulfone capsules have been already proposed to solve these drawbacks. Among them, PSf/Vanillin capsules were considered as a desirable system. They present both good material stability and high encapsulation capacity. However, several factors such as the final location of the perfume in the polymeric matrix, the aggregation state that it has in the capsule and its interaction with the capsule components have not been studied yet. These factors can provide vast information about the capsule performance and its improvement. With the aim to characterize these parameters, the physical and chemical properties of PSf/Vanillin capsules have been investigated by nuclear magnetic resonance (NMR) spectroscopy, scanning electron microscopy (SEM), atomic force microscopy (AFM), and N(2) adsorption-desorption measurements. AFM micrograph and N(2) isotherms confirm that the presence of vanillin modify the physical structure of PSf/Vanillin microcapsules as it is trapped in the capsule porosity. NMR results show that vanillin is present in solid state in PSf/Vanillin microcapsules.

  20. ANN - based distribution system reconfiguration

    SciTech Connect

    Momoh, J.A.; Wang, Yanchun; Rizy, D.T.

    1997-08-01

    This paper describes an Artificial Neural Network (ANN) - based distribution system reconfiguration scheme to reduce system loss. The ANN is trained for different load levels and different network topologies. The proposed scheme has been tested using a 38 - bus distribution system. The results are very promising.

  1. A Reconfigurable Active Huygens' Metalens.

    PubMed

    Chen, Ke; Feng, Yijun; Monticone, Francesco; Zhao, Junming; Zhu, Bo; Jiang, Tian; Zhang, Lei; Kim, Yongjune; Ding, Xumin; Zhang, Shuang; Alù, Andrea; Qiu, Cheng-Wei

    2017-02-24

    Metasurfaces enable a new paradigm to control electromagnetic waves by manipulating subwavelength artificial structures within just a fraction of wavelength. Despite the rapid growth, simultaneously achieving low-dimensionality, high transmission efficiency, real-time continuous reconfigurability, and a wide variety of reprogrammable functions is still very challenging, forcing researchers to realize just one or few of the aforementioned features in one design. This study reports a subwavelength reconfigurable Huygens' metasurface realized by loading it with controllable active elements. The proposed design provides a unified solution to the aforementioned challenges of real-time local reconfigurability of efficient Huygens' metasurfaces. As one exemplary demonstration, a reconfigurable metalens at the microwave frequencies is experimentally realized, which, to the best of the knowledge, demonstrates for the first time that multiple and complex focal spots can be controlled simultaneously at distinct spatial positions and reprogrammable in any desired fashion, with fast response time and high efficiency. The presented active Huygens' metalens may offer unprecedented potentials for real-time, fast, and sophisticated electromagnetic wave manipulation such as dynamic holography, focusing, beam shaping/steering, imaging, and active emission control.

  2. 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.

  3. Plasmonic-Based Mechanochromic Microcapsules as Strain Sensors.

    PubMed

    Burel, Céline A S; Alsayed, Ahmed; Malassis, Ludivine; Murray, Christopher B; Donnio, Bertrand; Dreyfus, Rémi

    2017-08-21

    Efficiently detecting mechanical deformations within materials is critical in a wide range of devices, from micro-electromechanical systems to larger structures in the aerospace industry. This communication reports the fabrication of new mechanochromic micrometer-size capsules enabling the detection of strains. These microcapsules are synthesized using an emulsification approach. They are made of densely packed gold nanoparticles embedded in a spherical silica crust. Billions of these composite spherical microcapsules are fabricated in a single batch. Each microcapsule is an opto-mechanosensor by itself, and can easily be recovered and incorporated into polymer films. When the films are stretched, the microcapsules are deformed into elongated ellipsoidal shapes and the distance between the Au NPs embedded in their shells concomitantly increases. As the extinction of Au NPs depends on the separation between the Au NPs, microcapsules exhibit different colors when they are elongated. These novel sensitive microcapsules can be used to detect and measure strain in polymer films by outputting color information. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. 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.

  5. Encapsulation of Vitamin A palmitate for animal supplementation: Formulation, manufacturing and stability implications.

    PubMed

    Albertini, Beatrice; Di Sabatino, Marcello; Calogerà, Giacomo; Passerini, Nadia; Rodriguez, Lorenzo

    2010-01-01

    Two manufacturing methods and numerous formulative approaches have been evaluated to obtain a stable oral pharmaceutical form of Vitamin A palmitate (VAP), a substance very sensitive to light, temperature, humidity and metal ions. The best results were obtained by formulating VAP, stabilized with butylated hydroxytoluene (BHT), in double layer microcapsules constituted by a core of chitosan, Tween 20, CaCl(2) and EDTA surrounded by a first chitosan-alginate membrane and an outer membrane of calcium-alginate. This formulation design enabled the production of beads with high drug loading (42% w/w) and high encapsulation efficiency (94%). The stability of VAP-loaded microcapsules was assessed according to EMEA guidelines. This formulation design showed the best performance in terms of VAP recovery (t(50%) > 360 days) after 1 year of storage at room conditions. This is a very important result considering the poor shelf-life (45 days) of pure VAP stabilized with BHT stored at the same conditions.

  6. Physico-chemical, antioxidant, and anti-inflammatory properties and stability of hawthorn (Crataegus monogyna Jacq.) procyanidins microcapsules with inulin and maltodextrin.

    PubMed

    Wyspiańska, Dorota; Kucharska, Alicja Z; Sokół-Łętowska, Anna; Kolniak-Ostek, Joanna

    2017-01-01

    Procyanidins from the bark of hawthorn (Crataegus monogyna Jacq.) were isolated and purified. Qualitative and quantitative composition was compared with that of the extract of hawthorn fruit (Crataegus monogyna Jacq.). Stability and antioxidant and anti-inflammatory properties of procyanidins before and after micro-encapsulation were estimated. The effects of the carrier type (inulin and maltodextrin) and procyanidins:carrier ratio (1:1, 1:3) and the influence of storage temperature (20 °C, -20 °C, -80 °C) on the content of procyanidins were evaluated. Samples before and after micro-encapsulation contained from 651 to 751 mg of procyanidins in 1 g. Among the procyanidins, (-)-epicatechin, dimer B2, and trimer C1 dominated. The use of inulin during spray drying resulted in greater efficiency of micro-encapsulation than the use of maltodextrin. During storage of the samples at 20 °C degradation of procyanidins was observed, whereas at -20 °C and -80 °C concentrations of them increased. The microcapsules with procyanidins from the bark of hawthorn, as well as the extract of procyanidins, have valuable biological activity, and strong antioxidant and anti-inflammatory properties. It is better to prepare microcapsules with a greater amount of carrier, with the procyanidin/carrier ratio 1:3. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

  7. Acute Toxicological Study of Ampicillin Anhydrate Microcapsules in Sprague-Dawley Rats.

    DTIC Science & Technology

    This document contains the results of an acute toxicological study to determine the toxicologic potential of ampicillin anhydrate microcapsules on...various organs of the rat. Keywords: Wound treatment; Antibiotic microcapsule ; Controlled release; Experimental data; Tables data. (aw)

  8. Production of hydrogen sulphide in milkfat-coated microcapsules containing Brevibacterium linens and cysteine.

    PubMed

    Kim, S C; Olson, N F

    1989-01-01

    Milkfat-coated microcapsules containing Brevibacterium linens and cysteine were used to produce hydrogen sulphide, one of Cheddar cheese flavour compounds. Hydrogen sulphide production was substantially reduced and delayed in the encapsulated system as compared with that of the unencapsulated system. Hydrogen sulphide was not produced aerobically whereas substantial amounts of hydrogen sulphide were produced in a nitrogen purged system. The inhibitory effect of the initial aerobic condition disappeared after 8 days of incubation. In spite of the lag in hydrogen sulphide production under aerobic conditions almost the same amount of hydrogen sulphide was produced in oxygen purged samples as in the nitrogen purged samples after 10 days of incubation. Moderate heat treatment (2 min at 58 degrees C) of cell suspension-milkfat-emulsion increased subsequent hydrogen sulphide production. The optimum pH and temperature for hydrogen sulphide production from cysteine by Brevibacterium linens were 6 degrees C and 32 degrees C, respectively. Antioxidants BHT, BHA and ascorbic acid had negligible effects on production of hydrogen sulphide in the encapsulated system.

  9. Polymeric nano/microcapsules of liquid perfluorocarbons for ultrasonic imaging: physical characterization.

    PubMed

    Pisani, E; Tsapis, N; Paris, J; Nicolas, V; Cattel, L; Fattal, E

    2006-04-25

    Ultrasonic imaging is a widely available, noninvasive, and cost-effective diagnostic modality, but vessels smaller than 200 mum in diameter are impossible to visualize. Commercial ultrasound contrast agents (UCAs), consisting of encapsulated gas microbubbles injected intravenously, enable only a qualitative visualization of the microvascularization for a short period of time since they are rather unstable. In a strategy to develop more stable UCAs, we designed a process to obtain nano/microcapsules with a single core of liquid perfluorocarbons within a biodegradable polymeric shell of homogeneous thickness. The polymer shell should improve the stability of the capsules as compared to UCAs stabilized by a monomolecular layer, while the acoustic impedance of the perfluorocarbons should ensure their echogenicity. These capsules have been optimized to encapsulate several liquid perfluorocarbons: perfluorohexane, perfluorodecalin, and perfluorooctyl bromide. The system is rather versatile: the mean size of the capsules can be adjusted between 70 nm and 25 microm and the thickness-to-radius ratio (T/R) can be easily modulated by simply modifying the polymer-to-perfluorocarbon ratio. T/R does not depend on the size of the capsules and is between 0.2 and 0.6. The dependence of the echogenic properties of the capsules with their size and their T/R has yet to be studied experimentally before this system can be evaluated in vivo.

  10. Stability of lactobacilli encapsulated in various microbial polymers.

    PubMed

    Jiménez-Pranteda, María Luján; Poncelet, Denis; Náder-Macías, María Elena; Arcos, Antonio; Aguilera, Margarita; Monteoliva-Sánchez, Mercedes; Ramos-Cormenzana, Alberto

    2012-02-01

    Various microbial polymers, namely xanthan gum, gellan gum, pullulan gum and jamilan, were tested as a suitable encapsulating material for Lactobacillus plantarum CRL 1815 and Lactobacillus rhamnosus ATCC 53103. Resulting capsules were also studied for their pH and simulated gastrointestinal conditions tolerance. The morphology of the microcapsules was studied using scanning electron microscopy. pH tolerance was tested at pH 2.0, 3.5, 5.0 and 6.5 over a 6h incubation period. Simulated gastrointestinal conditions were assayed with simulated gastric and pancreatic juices and simulated bile over a 24h incubation period. Suspensions of probiotic organisms were used as a control. The results from encapsulation with microbial polymers indicate that mixtures of 1% xanthan gum with 0.75% gellan gum and 1% jamilan with 1% gellan gum were the most suitable for microencapsulation. Results for the pH tolerance tests showed no improvement in the viability of cells in relation to the control, except for pH 2.0 where lactobacilli encapsulated in xanthan:gellan gum (1%:0.75%) prolonged their viability by 6h exposure. Xanthan:gellan gum (1%:0.75%) was the most effective of the encapsulating materials tested in protecting L. plantarum and L. rhamnosus against simulated bile, improving its viability in 1-2 logCFU when compared with control. The results of this study suggest that microbial polymers are an interesting source of encapsulating material that should be taken into account for prospective studies of probiotic encapsulation for oral delivery applications. Copyright © 2011 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

  11. 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.

  12. 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.

  13. 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.

  14. Characterization of viability and proliferation of alginate-poly-L-lysine-alginate encapsulated myoblasts using flow cytometry.

    PubMed

    Thakur, Ajit; Sengupta, Ruchira; Matsui, Hideto; Lillicrap, David; Jones, Kim; Hortelano, Gonzalo

    2010-08-01

    Genetically modified cells encapsulated in alginate-poly-L-lysine-alginate (APA) are being developed to deliver therapeutic products to treat a variety of diseases. The characterization of the encapsulated cells thus becomes paramount. This study reports a novel method to assess the viability, granularity and proliferation of encapsulated cells based on flow cytometry. The in vitro viability of encapsulated G8 murine myoblasts secreting canine FVIII (cFVIII) measured by flow cytometry was comparable to the traditional trypan blue exclusion method and both correlated with cFVIII secretion levels. In contrast, after implantation into mice, only viability measured by flow cytometry correlated with cFVIII secretion. Further, flow cytometry analysis of encapsulated cells maintained in vitro and in vivo revealed a greater fraction of granular cells compared to free cells, suggesting that encapsulation influences the morphology (cytoplasmic composition) of cells within APA microcapsules. Interestingly, the proliferation study showed that encapsulated cells proliferate faster, on average, and were more heterogeneous in vivo compared to in vitro culture conditions, suggesting that encapsulated cell proliferation is complex and environment-dependent. In conclusion, we show that flow cytometry analysis allows for a more consistent and comprehensive examination of encapsulated cells to aid in the development of cell therapy protocols.

  15. Effect of plasma components on the stability and permeability of microcapsule.

    PubMed

    Chen, Li; Zhang, Ying; Li, Shen; Wang, Xiuli; Li, Na; Wang, Yu; Guo, Xin; Zhao, Shan; Yu, Weiting; Sun, Guangwei; Liu, Yang; Ma, Xiaojun

    2014-07-01

    Immobilization of hepatocytes in microcapsules has been a potentially alternative methodology for bioartificial livers (BALs). Moreover, the stability and permeability are the key parameters of these microcapsules. However, these alginate-based microcapsules are unstable if the surrounding medium disrupts the ionic interactions between alginate and the polycation. As hundreds of components are included in human plasma, the stability and permeability in plasma of microcapsules need to be sufficiently investigated. In the present study, the stability of three kinds of alginate-based microcapsules was evaluated when they were immersed in plasma. Our results showed that stability of alginate-α-poly (L-lysine)-alginate (α-APA) microcapsules was well maintained, better than those of alginate-ε-poly (L-lysine)-alginate (ε-APA) and alginate-chitosan-alginate (ACA) microcapsules. Also, factors affecting the stability of microcapsules in plasma were analyzed and it showed that heparin was the key factor that affected the stability of α-APA microcapsules, whereas heparin and low molecular electrolytes such as HCO3(-) and H2 PO4(-)/HPO4(2-) were the factors to ε-APA and ACA microcapsules. In addition, the permeability evaluation showed no decrease in permeability of microcapsules after incubation in plasma. Our study might provide a foundation for the selection and modification of materials for microcapsule-based BAL devices.

  16. Biodegradable Bioadherent Microcapsules for Orally Administered Sustained Release Vaccines. Phase 1.

    DTIC Science & Technology

    1995-10-23

    composites produced by the helminth Fasciola hepatica for biological microencapsulation . The natural microcapsule can withstand treatment with strong...can take advantage of large batch fermentation technology. 3. Methods for Microencapsulation Numerous methods exist for the production of microcapsules ...Biodegradable Bioadherent Microcapsules for Orally Administered Sustained Release Vaccines PRINCIPAL INVESTIGATOR: Cynthia L. Sheffield, Ph.D

  17. Sustained release of verapamil hydrochloride from sodium alginate microcapsules.

    PubMed

    Farhana, S Ayesha; Shantakumar, S M; Shyale, Somashekar; Shalam, Md; Narasu, Laxmi

    2010-04-01

    The objective of the present study was to develop sustained release microcapsules of verapamil hydrochloride (VH) using biodegradable polymers. For this purpose microcapsules embedded verapamil hydrochloride were prepared using sodium alginate alone and also by incorporating some co polymers like methyl cellulose (MC), sodium carboxy methyl cellulose (SCMC) , poly vinyl pyrollidone (PVP) and xanthan gum by employing complex emulsion method of microencapsulation. Microcapsules were prepared in various core: coat ratios to know the effect of polymer and co polymers on drug release. Overall ten formulations were prepared and evaluated for flow behaviour, sieve analysis, drug entrapment efficiency, in vitro dissolution studies, stability studies, including scanning electron microscopy and DSC. The resulting microcapsules were discrete, large, spherical and also free flowing. The drug content in all the batches of microcapsules was found to be uniform. The release was depended on core: coat ratio and nature of the polymers. FTIR analysis revealed chemical integrity between Verapamil hydrochloride (VH), sodium alginate and between the copolymers. Among the four copolymers used methyl cellulose retarded the drug release more than the other three, hence the same formulation was subjected for in vivo studies. The drug release from the microcapsules was found to be following non fickian diffusion. Mechanism of drug release was diffusion controlled first order kinetics. Drug diffusion co efficient and correlation co efficient were also assessed by using various mathematical models. In vivo result analysis of pharmacokinetic parameters revealed that t max of reference and test formulations were almost same. From the study it was concluded that, sustained release Verapamil hydro chloride microcapsules could be achieved with success using sodium alginate alone and also in combination with other biodegradable polymers.

  18. 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.

  19. Bioluminescence tracking of alginate micro-encapsulated cell transplants.

    PubMed

    Tiernan, Aubrey R; Sambanis, Athanassios

    2017-02-01

    Cell-based therapies to treat loss-of-function hormonal disorders such as diabetes and Parkinson's disease are routinely coupled with encapsulation strategies, but an understanding of when and why grafts fail in vivo is lacking. Consequently, investigators cannot clearly define the key factors that influence graft success. Although bioluminescence is a popular method to track the survival of free cells transplanted in preclinical models, little is known of the ability to use bioluminescence for real-time tracking of microencapsulated cells. Furthermore, the impact that dynamic imaging distances may have, due to freely-floating microcapsules in vivo, on cell survival monitoring is unknown. This work addresses these questions by applying bioluminescence to a pancreatic substitute based on microencapsulated cells. Recombinant insulin-secreting cells were transduced with a luciferase lentivirus and microencapsulated in Ba(2+) crosslinked alginate for in vitro and in vivo studies. In vitro quantitative bioluminescence monitoring was possible and viable microencapsulated cells were followed in real time under both normoxic and anoxic conditions. Although in vivo dispersion of freely-floating microcapsules in the peritoneal cavity limited the analysis to a qualitative bioluminescence evaluation, signals consistently four orders of magnitude above background were clear indicators of temporal cell survival. Strong agreement between in vivo and in vitro cell proliferation over time was discovered by making direct bioluminescence comparisons between explanted microcapsules and parallel in vitro cultures. Broader application of this bioluminescence approach to retrievable transplants, in supplement to currently used end-point physiological tests, could improve understanding and accelerate development of cell-based therapies for critical clinical applications. Copyright © 2014 John Wiley & Sons, Ltd.

  20. An Embedded Reconfigurable Logic Module

    NASA Technical Reports Server (NTRS)

    Tucker, Jerry H.; Klenke, Robert H.; Shams, Qamar A. (Technical Monitor)

    2002-01-01

    A Miniature Embedded Reconfigurable Computer and Logic (MERCAL) module has been developed and verified. MERCAL was designed to be a general-purpose, universal module that that can provide significant hardware and software resources to meet the requirements of many of today's complex embedded applications. This is accomplished in the MERCAL module by combining a sub credit card size PC in a DIMM form factor with a XILINX Spartan I1 FPGA. The PC has the ability to download program files to the FPGA to configure it for different hardware functions and to transfer data to and from the FPGA via the PC's ISA bus during run time. The MERCAL module combines, in a compact package, the computational power of a 133 MHz PC with up to 150,000 gate equivalents of digital logic that can be reconfigured by software. The general architecture and functionality of the MERCAL hardware and system software are described.

  1. Reconfigurable Microwave Photonic Topological Insulator

    NASA Astrophysics Data System (ADS)

    Goryachev, Maxim; Tobar, Michael E.

    2016-12-01

    Using full 3D finite-element simulation and underlining Hamiltonian models, we demonstrate reconfigurable photonic analogues of topological insulators on a regular lattice of tunable posts in a reentrant 3D lumped element-type system. The tunability allows a dynamical in situ change of media chirality and other properties via the alteration of the same parameter for all posts, and as a result, great flexibility in the choice of bulk-edge configurations. Additionally, one-way photon transport without an external magnetic field is demonstrated. The ideas are illustrated by using both full finite-element simulation as well as simplified harmonic oscillator models. Dynamical reconfigurability of the proposed systems paves the way to a class of systems that can be employed for random access, topological signal processing, and sensing.

  2. Characterization Methods of Encapsulates

    NASA Astrophysics Data System (ADS)

    Zhang, Zhibing; Law, Daniel; Lian, Guoping

    Food active ingredients can be encapsulated by different processes, including spray drying, spray cooling, spray chilling, spinning disc and centrifugal co-extrusion, extrusion, fluidized bed coating and coacervation (see Chap. 2 of this book). The purpose of encapsulation is often to stabilize an active ingredient, control its release rate and/or convert a liquid formulation into a solid which is easier to handle. A range of edible materials can be used as shell materials of encapsulates, including polysaccharides, fats, waxes and proteins (see Chap. 3 of this book). Encapsulates for typical industrial applications can vary from several microns to several millimetres in diameter although there is an increasing interest in preparing nano-encapsulates. Encapsulates are basically particles with a core-shell structure, but some of them can have a more complex structure, e.g. in a form of multiple cores embedded in a matrix. Particles have physical, mechanical and structural properties, including particle size, size distribution, morphology, surface charge, wall thickness, mechanical strength, glass transition temperature, degree of crystallinity, flowability and permeability. Information about the properties of encapsulates is very important to understanding their behaviours in different environments, including their manufacturing processes and end-user applications. E.g. encapsulates for most industrial applications should have desirable mechanical strength, which should be strong enough to withstand various mechanical forces generated in manufacturing processes, such as mixing, pumping, extrusion, etc., and may be required to be weak enough in order to release the encapsulated active ingredients by mechanical forces at their end-user applications, such as release rate of flavour by chewing. The mechanical strength of encapsulates and release rate of their food actives are related to their size, morphology, wall thickness, chemical composition, structure etc. Hence

  3. Effect of the shell-forming polymer ratio on the encapsulation of tea tree oil by complex coacervation as a natural biocide.

    PubMed

    Pérez-Limiñana, María Ángeles; Payá-Nohales, Federico J; Arán-Ais, Francisca; Orgilés-Barceló, César

    2014-01-01

    The aim of this study was to develop footwear materials with antimicrobial properties using microencapsulated Tea Tree oil (TTO) as a natural biocide. For that purpose, gelatine-carboxymethylcellulose based microcapsules containing TTO were synthesised by a complex coacervation process. Furthermore, the influence of the gelatine (G)/sodium carboxymethylmethyl cellulose (CMC) ratio (G/C) on the microcapsule properties, as well as in the microencapsulation oil efficiency, was evaluated. The microcapsules were characterised by different experimental techniques and applied to footwear materials (leather and textile) to evaluate their performance. The microcapsule durability under different conditions, such as rubbing and ironing, was analysed in order to simulate shoe manufacturing and shoe wearing. The properties of the microcapsules obtained by complex coacervation, using gelatine and sodium carboxymethylcellulose as shell-forming polymers, are determined by the ratio between those two polymers (G/C). The results obtained showed a notable effect of G/C ratio on the formation of the coacervate during the synthesis process and also on the encapsulation efficiency of the antimicrobial oil, with the optimal value for the G/C ratio being around 10.

  4. Model-based reconfiguration: Diagnosis and recovery

    NASA Technical Reports Server (NTRS)

    Crow, Judy; Rushby, John

    1994-01-01

    We extend Reiter's general theory of model-based diagnosis to a theory of fault detection, identification, and reconfiguration (FDIR). The generality of Reiter's theory readily supports an extension in which the problem of reconfiguration is viewed as a close analog of the problem of diagnosis. Using a reconfiguration predicate 'rcfg' analogous to the abnormality predicate 'ab,' we derive a strategy for reconfiguration by transforming the corresponding strategy for diagnosis. There are two obvious benefits of this approach: algorithms for diagnosis can be exploited as algorithms for reconfiguration and we have a theoretical framework for an integrated approach to FDIR. As a first step toward realizing these benefits we show that a class of diagnosis engines can be used for reconfiguration and we discuss algorithms for integrated FDIR. We argue that integrating recovery and diagnosis is an essential next step if this technology is to be useful for practical applications.

  5. Effects of water-aging on self-healing dental composite containing microcapsules

    PubMed Central

    Wu, Junling; Weir, Michael D.; Melo, Mary Anne S.; Strassler, Howard E.; Xu, Hockin H. K.

    2016-01-01

    Objectives The objectives of this study were to develop a self-healing dental composite containing poly(urea-formaldehyde) (PUF) shells with triethylene glycol dimethacrylate (TEGDMA) and N,N-dihydroxyethyl-p-toluidine (DHEPT) as healing liquid, and to investigate the mechanical properties of the composite and its self-healing efficacy after water-aging for 6 months. Methods PUF microspheres were synthesized encapsulating a TEGDMA-DHEPT healing liquid. Composite containing 30% of a resin matrix and 70% of glass fillers by mass was incorporated with 0%, 2.5%, 5%, 7.5% and 10% of microcapsules. A flexural test was used to measure flexural strength and elastic modulus. A single edge V-notched beam method was used to measure fracture toughness (KIC) and self-healing efficacy. Specimens were water-aged at 37 °C for 1 d to 6 months and then tested for self-healing. Fractured specimens were healed while being immersed in water to examine self-healing efficacy, in comparison with that in air. Results Incorporation of up to 7.5% of microcapsules into the resin composite achieved effective self-healing, without adverse effects on the virgin mechanical properties of the composite (p > 0.1). An excellent self-healing efficacy of 64%–77% recovery was obtained (mean ± sd; n = 6). Six months of water-aging did not decrease the self-healing efficacy compared to 1 d (p > 0.1). Exposure to water did not decrease the healing efficacy, compared to that healed in air (p > 0.1). Conclusions A composite was developed with excellent self-healing efficacy even while being immersed in water. The self-healing efficacy did not decrease with increasing water-aging time for 6 months. Clinical significance The novel self-healing composite may be promising for dental applications to heal cracks, resist fracture, and increase the durability and longevity. PMID:26808158

  6. Effects of water-aging on self-healing dental composite containing microcapsules.

    PubMed

    Wu, Junling; Weir, Michael D; Melo, Mary Anne S; Strassler, Howard E; Xu, Hockin H K

    2016-04-01

    The objectives of this study were to develop a self-healing dental composite containing poly(urea-formaldehyde) (PUF) shells with triethylene glycol dimethacrylate (TEGDMA) and N,N-dihydroxyethyl-p-toluidine (DHEPT) as healing liquid, and to investigate the mechanical properties of the composite and its self-healing efficacy after water-aging for 6 months. PUF microspheres were synthesized encapsulating a TEGDMA-DHEPT healing liquid. Composite containing 30% of a resin matrix and 70% of glass fillers by mass was incorporated with 0%, 2.5%, 5%, 7.5% and 10% of microcapsules. A flexural test was used to measure flexural strength and elastic modulus. A single edge V-notched beam method was used to measure fracture toughness (KIC) and self-healing efficacy. Specimens were water-aged at 37 °C for 1 day to 6 months and then tested for self-healing. Fractured specimens were healed while being immersed in water to examine self-healing efficacy, in comparison with that in air. Incorporation of up to 7.5% of microcapsules into the resin composite achieved effective self-healing, without adverse effects on the virgin mechanical properties of the composite (p>0.1). An excellent self-healing efficacy of 64-77% recovery was obtained (mean±sd; n=6). Six months of water-aging did not decrease the self-healing efficacy compared to 1 day (p>0.1). Exposure to water did not decrease the healing efficacy, compared to that healed in air (p>0.1). A composite was developed with excellent self-healing efficacy even while being immersed in water. The self-healing efficacy did not decrease with increasing water-aging time for 6 months. The novel self-healing composite may be promising for dental applications to heal cracks, resist fracture, and increase the durability and longevity. Copyright © 2016 Elsevier Ltd. All rights reserved.

  7. Structural changes and imaging signatures of acoustically sensitive microcapsules under ultrasound.

    PubMed

    Sridhar-Keralapura, Mallika; Thirumalai, Shruthi; Mobed-Miremadi, Maryam

    2013-07-01

    The ultrasound drug delivery field is actively designing new agents that would obviate the problems of just using microbubbles for drug delivery. Microbubbles have very short circulation time (minutes), low payload and large size (2-10μm), all of these aspects are not ideal for systemic drug delivery. However, microbubble carriers provide excellent image contrast and their use for image guidance can be exploited. In this paper, we suggest an alternative approach by developing acoustically sensitive microcapsule reservoirs that have future applications for treating large ischemic tumors through intratumoral therapy. We call these agents Acoustically Sensitized Microcapsules (ASMs) and these are not planned for the circulation. ASMs are very simple in their formulation, robust and reproducible. They have been designed to offer high payload (because of their large size), be acoustically sensitive and reactive (because of the Ultrasound Contrast Agents (UCAs) encapsulated) and mechanically robust for future injections/implantations within tumors. We describe three different aspects - (1) effect of therapeutic ultrasound; (2) mechanical properties and (3) imaging signatures of these agents. Under therapeutic ultrasound, the formation of a cavitational bubble was seen prior to rupture. The time to rupture was size dependent. Size dependency was also seen when measuring mechanical properties of these ASMs. % Alginate and permeability also affected the Young's modulus estimates. For study of imaging signatures of these agents, we show six schemes. For example, with harmonic imaging, tissue phantoms and controls did not generate higher harmonic components. Only ASM phantoms created a harmonic signal, whose sensitivity increased with applied acoustic pressure. Future work includes developing schemes combining both sonication and imaging to help detect ASMs before, during and after release of drug substance.

  8. 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.

  9. Investigation of the colon-targeting, improvement on the side-effects and therapy on the experimental colitis in mouse of a resin microcapsule loading dexamethasone sodium phosphate.

    PubMed

    Zeng, Aiguo; Dong, Kai; Wang, Maoling; Sun, Jinyao; Dong, Yalin; Wang, Ke; Guo, Chenning; Yan, Yan; Zhang, Lu; Shi, Xianpeng; Xing, Jianfeng

    2016-07-01

    Dexamethasone is the major drug in the treatment of ulcerative colitis (UC). However, the extensive or long-time use of dexamethasone causes many toxic side-effects. Ion exchange resins react with external-ions through their own functional groups and Eudragit S occurs degradation when pH > 7. These features make them suitable for oral delivery system. Resin microcapsule (DRM) composed by 717 anion exchange resin and Eudragit S100 was used to target dexamethasone to the colon to improve its treatment effect on UC and reduce its toxic side-effects. Dexamethasone sodium phosphate (DXSP) was sequentially encapsulated in 717 anion-exchange resin and Eudragit S100 to prepare the DXSP-loaded resin microcapsule (DXSP-DRM). The in vitro release study and in vivo study of pharmacokinetics and the intestinal drug residues in rat demonstrated the good colon-targeting of DXSP-DRM. Moreover, the DXSP-DRM can reduce the toxic side-effects induced by DXSP and have good therapeutic effects on colitis mouse induced by 2,4,6-trinitrobenzenesulfonic acid. Dexamethasone can be targeted to the colon by DRM, thereby enhancing its treatment effect and reducing its toxic side effects. The resin microcapsule system has good colon-targeting and can be used in the development of colon-targeted preparations.

  10. Robust composite-shell microcapsules via pickering emulsification.

    PubMed

    Patchan, Marcia W; Fuller, Benedict W; Baird, Lance M; Gong, Paul K; Walter, Erich C; Vidmar, Brendan J; Kyei, Ike; Xia, Zhiyong; Benkoski, Jason J

    2015-04-08

    Microencapsulation technology has been increasingly applied toward the development of self-healing paints. Added to paint as a dry powder prior to spraying, the microcapsules store a liquid that can repair the protective barrier layer if released into a scratch. However, self-healing will not occur unless the microcapsules can withstand spray-painting, aggressive solvents in the paint, and long-term exposure to the elements. We have therefore developed a one-pot synthesis for the production of Pickering microcapsules with outstanding strength, solvent resistance, and barrier properties. Octadecyltrimethoxysilane-filled (OTS) microcapsules form via standard interfacial polycondensation, except that silica nanopowder (10-20 nm diameter) replaces the conventional surfactant or hydrocolloid emulsifier. Isophorone diisocyanate (IPDI) in the OTS core reacts with diethylenetriamine, polyethylenimine, and water to form a hard polymer shell along the interface. Compared to pure polyurea, the silica-polyurea composite improves the shelf life of the OTS by 10 times. The addition of SiO2 prevents leaching of OTS into xylenes and hexanes for up to 80 days, and the resulting microcapsules survive nebulization through a spray gun at 620 kPa in a 500 cSt fluid.

  11. 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.

  12. Cosmetic textiles with biological benefits: gelatin microcapsules containing vitamin C.

    PubMed

    Cheng, Shuk Yan; Yuen, Marcus Chun Wah; Kan, Chi Wai; Cheuk, Kevin Ka Leung; Chui, Chung Hin; Lam, Kim Hung

    2009-10-01

    In recent years, textile materials with special applications in the cosmetic field have been developed. A new sector of cosmetic textiles is opened up and several cosmetic textile products are currently available in the market. Microencapsulation technology is an effective technique to control the release properties of active ingredients that prolong the functionality of cosmetic textiles. This study discusses the development of cosmetic textiles and addresses microencapsulation technology with respect to its historical background, significant advantages, microencapsulation methods and recent applications in the textile industry. Gelatin microcapsules containing vitamin C were prepared using emulsion hardening technique. Both the optical microscopy and scanning electron microscopy demonstrated that the newly developed microcapsules were in the form of core-shell spheres with relatively smooth surface. The particle size of microcapsules ranged from 5.0 to 44.1 microm with the average particle size being 24.6 microm. The gelatin microcapsules were proved to be non-cytotoxic based on the research findings of the toxicity studies conducted on human liver and breast cell lines as well as primary bone marrow culture obtained from patient with non-malignant haematological disorder. The gelatin microcapsules were successfully grafted into textile materials for the development of cosmetic textiles.

  13. Photoresponsive Self-Healing Polymer Composite with Photoabsorbing Hybrid Microcapsules.

    PubMed

    Gao, Lei; He, Jinliang; Hu, Jun; Wang, Chao

    2015-11-18

    Microcapsule-based self-healing polymer materials are highly desirable because they can heal large-volume cracks without changing the original chemical structures of polymers. However, they are limited by processing difficulties and inhomogeneous distributions of two components. Herein, we report a one-component photoresponsive self-healing polymer composite with photoabsorbing hybrid microcapsules (PAHM), which gives the microcapsules photoabsorbing properties by introducing nano-TiO2 particles as photoabsorbing and emulsified agents in the poly(urea-formaldehyde)/TiO2 hybrid shells. Upon mechanical damage and then exposure to light, the photoresponsive healing agents in the cracks will be solidified to allow for self-healing, while the healing agents in the unbroken PAHM will be protected and remain unreacted, which endows this photoresponsive microcapsule-based self-healing composite with self-healing properties like those found in the conventional two-component microcapsule-based systems. Given the universality of this hybrid polymerization method, incorporation of the photoabsorbing particles to conventional polymer shells may further broaden the scope of applications of these widely used materials.

  14. 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.

  15. Reconfigurable metamaterials for terahertz wave manipulation.

    PubMed

    Hashemi, Mohammed R; Cakmakyapan, Semih; Jarrahi, Mona

    2017-09-01

    Reconfigurable metamaterials have emerged as promising platforms for manipulating the spectral and spatial properties of terahertz waves without being limited by the characteristics of naturally existing materials. Here, we present a comprehensive overview of various types of reconfigurable metamaterials that are utilized to manipulate the intensity, phase, polarization, and propagation direction of terahertz waves. We discuss various reconfiguration mechanisms based on optical, electrical, thermal, and mechanical stimuli while using semiconductors, superconductors, phase-change materials, graphene, and electromechanical structures. The advantages and disadvantages of different reconfigurable metamaterial designs in terms of modulation efficiency, modulation bandwidth, modulation speed, and system complexity are discussed in detail.

  16. Reconfigurable metamaterials for terahertz wave manipulation

    NASA Astrophysics Data System (ADS)

    Hashemi, Mohammed R.; Cakmakyapan, Semih; Jarrahi, Mona

    2017-09-01

    Reconfigurable metamaterials have emerged as promising platforms for manipulating the spectral and spatial properties of terahertz waves without being limited by the characteristics of naturally existing materials. Here, we present a comprehensive overview of various types of reconfigurable metamaterials that are utilized to manipulate the intensity, phase, polarization, and propagation direction of terahertz waves. We discuss various reconfiguration mechanisms based on optical, electrical, thermal, and mechanical stimuli while using semiconductors, superconductors, phase-change materials, graphene, and electromechanical structures. The advantages and disadvantages of different reconfigurable metamaterial designs in terms of modulation efficiency, modulation bandwidth, modulation speed, and system complexity are discussed in detail.

  17. Reconfiguration of Analog Electronics for Extreme Environments

    NASA Technical Reports Server (NTRS)

    Stoica, Adrian; Zebulum, Ricardo; Keymeulen, Didier; Guo, Xin

    2005-01-01

    This paper argues in favor of adaptive reconfiguration as a technique to expand the operational envelope of analog electronics for extreme environments (EE). On a reconfigurable device, although component parameters change in EE, as long as devices still operate, albeit degraded, a new circuit design, suitable for new parameter values, may be mapped into the reconfigurable structure to recover the initial circuit function. Laboratory demonstrations of this technique were performed by JPL in several independent experiments in which bulk CMOS reconfgurable devices were exposed to, and degraded by, high temperatures (approx.300 C) or radiation (300kRad TID), and then recovered by adaptive reconfiguration using evolutionary search algorithms.

  18. Dynamically reconfigurable complex emulsions via tunable interfacial tensions

    NASA Astrophysics Data System (ADS)

    Zarzar, Lauren D.; Sresht, Vishnu; Sletten, Ellen M.; Kalow, Julia A.; Blankschtein, Daniel; Swager, Timothy M.

    2015-02-01

    Emulsification is a powerful, well-known technique for mixing and dispersing immiscible components within a continuous liquid phase. Consequently, emulsions are central components of medicine, food and performance materials. Complex emulsions, including Janus droplets (that is, droplets with faces of differing chemistries) and multiple emulsions, are of increasing importance in pharmaceuticals and medical diagnostics, in the fabrication of microparticles and capsules for food, in chemical separations, in cosmetics, and in dynamic optics. Because complex emulsion properties and functions are related to the droplet geometry and composition, the development of rapid, simple fabrication approaches allowing precise control over the droplets' physical and chemical characteristics is critical. Significant advances in the fabrication of complex emulsions have been made using a number of procedures, ranging from large-scale, less precise techniques that give compositional heterogeneity using high-shear mixers and membranes, to small-volume but more precise microfluidic methods. However, such approaches have yet to create droplet morphologies that can be controllably altered after emulsification. Reconfigurable complex liquids potentially have great utility as dynamically tunable materials. Here we describe an approach to the one-step fabrication of three- and four-phase complex emulsions with highly controllable and reconfigurable morphologies. The fabrication makes use of the temperature-sensitive miscibility of hydrocarbon, silicone and fluorocarbon liquids, and is applied to both the microfluidic and the scalable batch production of complex droplets. We demonstrate that droplet geometries can be alternated between encapsulated and Janus configurations by varying the interfacial tensions using hydrocarbon and fluorinated surfactants including stimuli-responsive and cleavable surfactants. This yields a generalizable strategy for the fabrication of multiphase emulsions with

  19. Dynamically reconfigurable complex emulsions via tunable interfacial tensions

    PubMed Central

    Zarzar, Lauren D.; Sresht, Vishnu; Sletten, Ellen M.; Kalow, Julia A.; Blankschtein, Daniel; Swager, Timothy M.

    2015-01-01

    Emulsification is a powerful, well-known technique for mixing and dispersing immiscible components within a continuous liquid phase. Consequently, emulsions are central components of medicine, food and performance materials. Complex emulsions, including multiple emulsions and Janus droplets which contain hemispheres of differing material, are of increasing importance1 in pharmaceuticals and medical diagnostics2, in the fabrication of microparticles and capsules3–5 for food6, in chemical separations7, in cosmetics8, and in dynamic optics9. Because complex emulsion properties and functions are related to the droplet geometry and composition, the development of rapid, simple fabrication approaches allowing precise control over the droplets’ physical and chemical characteristics is critical. Significant advances in the fabrication of complex emulsions have been made using a number of procedures, ranging from large-scale, less precise techniques that give compositional heterogeneity using high-shear mixers and membranes10, to small-volume but more precise microfluidic methods11,12. However, such approaches have yet to create droplet morphologies that can be controllably altered after emulsification. Reconfigurable complex liquids potentially have greatly increased utility as dynamically tunable materials. Here we describe an approach to the one-step fabrication of three- and four-phase complex emulsions with highly controllable and reconfigurable morphologies. The fabrication makes use of the temperature-sensitive miscibility of hydrocarbon, silicone and fluorocarbon liquids, and is applied to both the microfluidic and the scalable batch production of complex droplets. We demonstrate that droplet geometries can be alternated between encapsulated and Janus configurations by varying the interfacial tensions using hydrocarbon and fluorinated surfactants including stimuli-responsive and cleavable surfactants. This yields a generalizable strategy for the fabrication of

  20. Stability of probiotic Lactobacillus plantarum in dry microcapsules under accelerated storage conditions.

    PubMed

    Albadran, Hanady A; Chatzifragkou, Afroditi; Khutoryanskiy, Vitaliy V; Charalampopoulos, Dimitris

    2015-08-01

    This study investigated the stability of freeze dried and fluid bed dried alginate microcapsules coated with chitosan containing model probiotic bacteria, Lactobacillus plantarum, during storage for up to 45days at different water activities (0.11, 0.23, 0.40 and 0.70) and temperatures (4, 30 and 37°C). The loss in cell viability was around 0.8 log in the case of fluid bed drying and around 1.3 in the case of freeze drying, with the former method resulting in dried capsules of smaller size (~1mm vs 1.3mm), more irregular shape, and with a rougher surface. In both cases, the water activity and water content were less than 0.25 and 10% w/w, respectively, which favours high storage stability. The storage stability studies demonstrated that as the water activity and temperature decreased the survival of the dried encapsulated cells increased. Considerably better survival was observed for fluid bed dried encapsulated cells compared to freeze dried encapsulated cells and freeze dried free cells with 10% sucrose (control), and in some cases, e.g. at 4 and 30°C at water activities of 0.11, 0.23 and 0.40, there was more than 1 log difference after 45days, with concentrations higher than 10(8)CFU/g after 45days of storage. The results indicate that fluid bed drying is an effective and efficient manufacturing method to produce probiotic containing capsules with enhanced storage stability. Copyright © 2015 Elsevier Ltd. All rights reserved.

  1. Preparation and properties of polyurea microcapsules with non-ionic surfactant as emulsifier.

    PubMed

    Yan, N; Ni, P; Zhang, M

    1993-01-01

    Polyurea microcapsules containing oily substances were prepared by using cyanate and polyamine as the monomers with non-ionic surfactant as the emulsifiers. Results showed that TDI-DETA microcapsules had the best stability. The mean diameter decreased and the size distribution curves became narrower and sharper as the stirring speed and the emulsifier concentration during emulsification increased. Addition of Tween 80 to aqueous solution containing OP led to an increase in microcapsule diameter and wider distribution of microcapsules due to the changes in interfacial tension. The isoelectric point of the polyurea microcapsules was found to be pH 5.8.

  2. 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.

  3. 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.

  4. Evaluation of microencapsulation of the UFV-AREG1 bacteriophage in alginate-Ca microcapsules using microfluidic devices.

    PubMed

    Boggione, Delaine M G; Batalha, Laís S; Gontijo, Marco T P; Lopez, Maryoris E S; Teixeira, Alvaro V N C; Santos, Igor J B; Mendonça, Regina C S

    2017-06-28

    The indiscriminate use of antibiotics and the emergence of resistant microorganisms have become a major challenge for the food industry. The purpose of this work was to microencapsulate the bacteriophage UFV-AREG1 in a calcium alginate matrix using microfluidic devices and to study the viability and efficiency of retention. The microcapsules were added to gel of propylene glycol for use as an antimicrobial in the food industry. The technique showed the number of the phage encapsulation, yielding drops with an average 100-250μm of diameter, 82.1±2% retention efficiency and stability in the gel matrix for 21days. The gel added to the microencapsulated phage showed efficiency (not detectable on the surface) in reducing bacterial contamination on the surface at a similar level to antimicrobial chemicals (alcohol 70%). Therefore, it was possible to microencapsulate bacteriophages in alginate-Ca and apply the microcapsules in gels for use as sanitizers in the food industry. Copyright © 2017 Elsevier B.V. All rights reserved.

  5. Consumer Acceptance of Bars and Gummies with Unencapsulated and Encapsulated Resveratrol.

    PubMed

    Koga, Clarissa C; Lee, Soo-Yeun; Lee, Youngsoo

    2016-05-01

    The addition of resveratrol, a polyphenol found in red wine and peanuts, to food products would help to provide the health benefits associated with the compound to the consumer in a wide array of food matrices. The bitterness of resveratrol and instability of its bioactive form in light are 2 major challenges with the incorporation of the compound into food products. Microencapsulation in a sodium caseinate matrix was utilized as a strategy to overcome these challenges. The objective of this research was to show the application of the resveratrol microcapsules in easy-to-consume foods. Consumer acceptance was evaluated for gummies and bars with encapsulated resveratrol in comparison to the controls. Four different controls were used: 1) without any resveratrol OR protein (Plain), 2) unencapsulated resveratrol (Resv), 3) sodium caseinate and unencapsulated resveratrol just mixed without encapsulation (P + R), and 4) sodium caseinate only (PRO). Two concentrations of resveratrol that have been shown to offer therapeutic effects in humans were tested (10 and 40 mg/d). The overall liking, evaluated using a 9-point scale, of bars with 10 mg of encapsulated resveratrol did not differ significantly from the control without any added resveratrol and protein (Plain) or from the controls with equivalent protein and/or resveratrol concentrations. For gummies, the samples with the resveratrol microcapsules had a significantly lower overall liking than the controls with the same protein and/or resveratrol content. This research demonstrated application of resveratrol microcapsules into easy-to-consume food products in order to deliver the health benefits to the consumer.

  6. Autonomic Healing of Epoxy Using Micro-Encapsulated Dicyclopentadiene

    SciTech Connect

    THOMA, STEVEN G.; GIUNTA, RACHEL K.; STAVIG, MARK E.; EMERSON, JOHN A.; MORALES, ALFREDO M.

    2003-05-01

    The autonomic healing ability of an epoxy adhesive containing micro-encapsulated dicyclopentadiene (DCPD) was evaluated. The epoxy resin used was Epon 828 cured with either Versamid 140 or diethylenetriamine (DETA). Variables included total weight percent of microcapsules (MCs) and catalyst, as well as the catalyst to DCPD ratio. The degree of healing was determined by the fracture toughness before and after ''healing'' using double-cantilever beam analysis. It was found that the degree of self-healing was most directly related to the contact area (i.e. crack width) during healing. Temperature also played a significant role. Observed differences between the results of this study and those in literature are discussed.

  7. Application of microcapsulation technology to the preparation of carbon foam.

    PubMed

    Li, Ke-Zhi; Shi, Zhen-Hai; Li, He-Jun; Tian, Zhuo; Wang, Chuang

    2008-04-01

    Microcapsules were prepared by in situ polymerization and microcapsulation. Tetraethyl orthosilicate was used as the core material and phenolic resin was used as the wall material in an emulsion system of polyacrylic and tetraethyl orthosilicate. The obtained microcapsules were slowly heated such that the core material was released by evaporation, leaving hollow-core spheres. The spheres were mixed with a phenolic resin-derived binder and molded to obtain a carbon foam precursor, which was carbonized at 1100 °C under the protection of N2 gas and graphitized at 2300 °C under the protection of Ar gas. Thus, the carbon foam of hollow closed-shelled microspheres with a graphitic structure was prepared. The properties and structure of this foam were discussed.

  8. Application of microcapsulation technology to the preparation of carbon foam

    PubMed Central

    Li, Ke-zhi; Shi, Zhen-hai; Li, He-jun; Tian, Zhuo; Wang, Chuang

    2008-01-01

    Microcapsules were prepared by in situ polymerization and microcapsulation. Tetraethyl orthosilicate was used as the core material and phenolic resin was used as the wall material in an emulsion system of polyacrylic and tetraethyl orthosilicate. The obtained microcapsules were slowly heated such that the core material was released by evaporation, leaving hollow-core spheres. The spheres were mixed with a phenolic resin-derived binder and molded to obtain a carbon foam precursor, which was carbonized at 1100 °C under the protection of N2 gas and graphitized at 2300 °C under the protection of Ar gas. Thus, the carbon foam of hollow closed-shelled microspheres with a graphitic structure was prepared. The properties and structure of this foam were discussed. PMID:27877986

  9. Plastic behaviour of polyelectrolyte microcapsules derived from colloid templates.

    PubMed

    Bäumler, H; Artmann, G; Voigt, A; Mitlöhner, R; Neu, B; Kiesewetter, H

    2000-01-01

    The deformability and osmotic properties of hollow microcapsules were studied by means of the micropipette video microscopic technique. The microcapsules were prepared by consecutive multiple adsorption of the polyanion, poly(styrene sulphonate), and the polycation, poly(allylamine hydrochloride), onto melamine formaldehyde resin latex of 5 microm diameter, which was decomposed after completing the coating by transferring to hydrochloric acid of pH 1.1. The polyelectrolyte microcapsules reacted to micropipette suction with plastic deformation. If lipids are added to the polyelectrolyte layers, the capsules cannot be visibly deformed by micropipette suction up to 10(4) N/m2. However, plastic shrinking was observed if the stress was generated by the osmotic pressure of a sucrose solution of 10(6) N/m2.

  10. 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

    2008-03-04

    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.

  11. Simulative method for the optical processor reconfiguration on a dynamically reconfigurable optical platform.

    PubMed

    Wang, Hongjian; Song, Kai

    2012-01-10

    With the reconfiguration technique, users can configure the optical processor of a new optical computing platform, the ternary optical computer (TOC), into 42 specific basic operation units, and reconfigure it when the computation is completed. A simulative method of software for this technique is proposed in this paper. Also, an elaborate experiment based on this software is discussed. This simulation of reconfiguration demonstrates that the theory of reconfiguring optical processor in TOC is valid and also lays the foundation for the hardware implementation of the reconfiguration technique. © 2012 Optical Society of America

  12. Impact of molecular weight on the formation of electrosprayed chitosan microcapsules as delivery vehicles for bioactive compounds.

    PubMed

    Gómez-Mascaraque, Laura G; Sanchez, Gloria; López-Rubio, Amparo

    2016-10-05

    The molecular weight of chitosan is one of its most determinant characteristics, which affects its processability and its performance as a biomaterial. However, information about the effect of this parameter on the formation of electrosprayed chitosan microcapsules is scarce. In this work, the impact of chitosan molecular weight on its electrosprayability was studied and correlated with its effect on the viscosity, surface tension and electrical conductivity of solutions. A Discriminant Function Analysis revealed that the morphology of the electrosprayed chitosan materials could be correctly predicted using these three parameters for almost 85% of the samples. The suitability of using electrosprayed chitosan capsules as carriers for bioactive agents was also assessed by loading them with a model active compound, (-)-epigallocatechin gallate (EGCG). This encapsulation, with an estimated efficiency of around 80% in terms of preserved antioxidant activity, showed the potential to prolong the antiviral activity of EGCG against murine norovirus via gradual bioactive release combined with its protection against degradation in simulated physiological conditions.

  13. Ultrasonic encapsulation - A review.

    PubMed

    Leong, Thomas S H; Martin, Gregory J O; Ashokkumar, Muthupandian

    2017-03-01

    Encapsulation of materials in particles dispersed in water has many applications in nutritional foods, imaging, energy production and therapeutic/diagnostic medicine. Ultrasonic technology has been proven effective at creating encapsulating particles and droplets with specific physical and functional properties. Examples include highly stable emulsions, functional polymeric particles with environmental sensitivity, and microspheres for encapsulating drugs for targeted delivery. This article provides an overview of the primary mechanisms arising from ultrasonics responsible for the formation of these materials, highlighting examples that show promise particularly in the development of foods and bioproducts.

  14. 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

  15. Microelectromechanical Systems (MEMS) Actuators for Antenna Reconfigurability

    NASA Technical Reports Server (NTRS)

    Simons, Rainee N.; Chun, Donghoon; Katehi, Linda P. B.

    2001-01-01

    A novel microelectromechanical systems (MEMS) actuator for patch antenna reconfiguration, is presented for the first time. A key feature is the capability of multi-band operation without greatly increasing the antenna element dimensions. Experimental results demonstrate that the center frequency can be reconfigured from few hundred MHz to few GHz away from the nominal operating frequency.

  16. Anode circuit reconfiguration of two sedimentation basins

    SciTech Connect

    Lewis, M.

    1999-12-01

    Upgrades at two sedimentation basins of a water treatment plant necessitated reconfiguration of the cathodic protection system. Modifications to the anode circuit and improvements to the corrosion monitoring system were implemented. The reconfiguration included the use of continuous strings of tubular mixed metal oxide (MMO) anode assemblies.

  17. Robust Reconfiguration of A Distribution System

    SciTech Connect

    Moradzadeh, Benyamin; Tomsovic, Kevin

    2017-01-01

    In this paper, a robust reconfiguration approach based on Mixed Integer Programming (MIP) is proposed to minimize loss in distribution systems. A Depth-First Search (DFS) algorithm to enumerate possible loops provides radiality constraint. This provides a general solution to the radiality constraint for distribution system reconfiguration/expansion problems. Still, imprecision and ambiguity in net loads, i.e. load minus renewable generation, due to lack of sufficient measurements and high utilization of demand response programs and renewable resources, creates challenges for effective reconfiguration. Deterministic optimization of reconfiguration may no lead to optimal/feasible results. Two methods to address these uncertainties are introduced in this paper: one, based on a stochastic MIP (SMIP) formulation and two, based on a fuzzy MIP (FMIP) formulation. Case studies demonstrate the robustness and efficiency of the proposed reconfiguration methods.

  18. Continuous reconfiguration: fault tolerance without a ripple

    SciTech Connect

    Bortner, R.A.

    1983-01-01

    The concepts of the continuously reconfiguring flight control system (crm/sup 2/fcs) and the impact of its architecture upon fault tolerance and reliability are covered. Some of the topics discussed are continuous reconfiguration, autonomous control, virtual common memory and the fault filter. Continuous reconfiguration is defined. An example is discussed with an explanation of transparent failure. Autonomous control is the scheme for controlling a continually reconfiguring system. The process of volunteering is also discussed. The virtual common memory is the common memory architecture used in the continuously reconfiguring system. Its physical implementation is explained. The fault filter is the method used to detect and deal with faulty processors. The different levels and the types of faults each handles are examined. 1 ref.

  19. Accelerating artificial intelligence with reconfigurable computing

    NASA Astrophysics Data System (ADS)

    Cieszewski, Radoslaw

    Reconfigurable computing is emerging as an important area of research in computer architectures and software systems. Many algorithms can be greatly accelerated by placing the computationally intense portions of an algorithm into reconfigurable hardware. Reconfigurable computing combines many benefits of both software and ASIC implementations. Like software, the mapped circuit is flexible, and can be changed over the lifetime of the system. Similar to an ASIC, reconfigurable systems provide a method to map circuits into hardware. Reconfigurable systems therefore have the potential to achieve far greater performance than software as a result of bypassing the fetch-decode-execute operations of traditional processors, and possibly exploiting a greater level of parallelism. Such a field, where there is many different algorithms which can be accelerated, is an artificial intelligence. This paper presents example hardware implementations of Artificial Neural Networks, Genetic Algorithms and Expert Systems.

  20. Effect of polyisobutylene on ethyl cellulose-walled microcapsules: wall structure and thickness of salicylamide and theophylline microcapsules.

    PubMed

    Benita, S; Donbrow, M

    1982-02-01

    Microcapsules were prepared by the ethylcellulose coacervation process which is based on the differential thermal solubility in cyclohexane. When a protective colloid, polyisobutylene, was present in adequate concentration, individually film-coated core particles formed. However, they were accompanied by small empty coacervate droplets, detectable by microscopic observation. Below the critical colloid concentration, the product had the form of aggregate, in contrast to individual film-coated microcapsules. Increase of colloid concentration yielded microcapsules of higher drug content, because coating became progressively thinner; there was a corresponding increase in the release rate of drugs from the microcapsules. Since the initial wall polymer/drug ratio and the particle size are constant, the drug content varied with the thicknesses of the wall membrane. This is shown here by removal of empty coacervate droplets by repeated decantations, enabling determination of drug content by chemical analysis. In contrast to results reported in the literature, in the presence of a protective colloid, microcapsule drug content decreased with decreasing particle size of the drug. This was caused by more complete uptake of the wall polymer on the increased surface of core material. The effect of protective colloid concentration on the apparent loss of wall polymer as empty droplets closely paralleled its effect on the size of stabilized droplet formation is a side reaction when core material is present, causing changes in wall thickness. This reaction not only affects the efficiency of the coating process but may be utilized to control wall thickness. First-order constants for drug release from salicylamide and theophylline microcapsules followed the same pattern as wall thickness and confirmed the validity of the measurements.

  1. Encapsulation with structured triglycerides

    USDA-ARS?s Scientific Manuscript database

    Lipids provide excellent materials to encapsulate bioactive compounds for food and pharmaceutical applications. Lipids are renewable, biodegradable, and easily modified to provide additional chemical functionality. The use of structured lipids that have been modified with photoactive properties are ...

  2. Hepatocyte-Like Cells Derived from Human Amniotic Epithelial Cells Can Be Encapsulated Without Loss of Viability or Function In Vitro

    PubMed Central

    Vaghjiani, Vijesh; Vaithilingam, Vijayaganapathy; Saraswati, Indah; Sali, Adnan; Murthi, Padma; Kalionis, Bill; Tuch, Bernard E.

    2014-01-01

    Placenta derived human amniotic epithelial cells (hAEC) are an attractive source of stem cells for the generation of hepatocyte-like cells (HLC) for therapeutic applications to treat liver diseases. During hAEC differentiation into HLC, they become increasingly immunogenic, which may result in immune cell-mediated rejection upon transplantation into allogeneic recipients. Placing cells within devices such as alginate microcapsules can prevent immune cell-mediated rejection. The aim of this study was to investigate the characteristics of HLC generated from hAEC and to examine the effects of encapsulation on HLC viability, gene expression, and function. hAEC were differentiated for 4 weeks and evaluated for hepatocyte-specific gene expression and function. Differentiated cells were encapsulated in barium alginate microcapsules and cultured for 7 days and the effect of encapsulation on cell viability, function, and hepatocyte related gene expression was determined. Differentiated cells performed key functions of hepatocytes including urea synthesis, drug-metabolizing cytochrome P450 (CYP)3A4 activity, indocyanine green (ICG) uptake, low-density lipoprotein (LDL) uptake, and exhibited glutathione antioxidant capacity. A number of hepatocyte-related genes involved in fat, cholesterol, bile acid synthesis, and xenobiotic metabolism were also expressed showing that the hAEC had differentiated into HLC. Upon encapsulation, the HLC remained viable for at least 7 days in culture, continued to express genes involved in fat, cholesterol, bile acid, and xenobiotic metabolism and had glutathione antioxidant capacity. CYP3A4 activity and urea synthesis by the encapsulated HLC were higher than that of monolayer HLC cultures. Functional HLC can be derived from hAEC, and HLC can be encapsulated within alginate microcapsules without losing viability or function in vitro. PMID:24295364

  3. Transformational electronics are now reconfiguring

    NASA Astrophysics Data System (ADS)

    Rojas, Jhonathan P.; Hussain, Aftab M.; Arevalo, A.; Foulds, I. G.; Torres Sevilla, Galo A.; Nassar, Joanna M.; Hussain, Muhammad M.

    2015-05-01

    Current developments on enhancing our smart living experience are leveraging the increased interest for novel systems that can be compatible with foldable, wrinkled, wavy and complex geometries and surfaces, and thus become truly ubiquitous and easy to deploy. Therefore, relying on innovative structural designs we have been able to reconfigure the physical form of various materials, to achieve remarkable mechanical flexibility and stretchability, which provides us with the perfect platform to develop enhanced electronic systems for application in entertainment, healthcare, fitness and wellness, military and manufacturing industry. Based on these novel structural designs we have developed a siliconbased network of hexagonal islands connected through double-spiral springs, forming an ultra-stretchable (~1000%) array for full compliance to highly asymmetric shapes and surfaces, as well as a serpentine design used to show an ultrastretchable (~800%) and flexible, spatially reconfigurable, mobile, metallic thin film copper (Cu)-based, body-integrated and non-invasive thermal heater with wireless controlling capability, reusability, heating-adaptability and affordability due to low-cost complementary metal oxide semiconductor (CMOS)-compatible integration.

  4. Reconfigurable L-Band Radar

    NASA Technical Reports Server (NTRS)

    Rincon, Rafael F.

    2008-01-01

    The reconfigurable L-Band radar is an ongoing development at NASA/GSFC that exploits the capability inherently in phased array radar systems with a state-of-the-art data acquisition and real-time processor in order to enable multi-mode measurement techniques in a single radar architecture. The development leverages on the L-Band Imaging Scatterometer, a radar system designed for the development and testing of new radar techniques; and the custom-built DBSAR processor, a highly reconfigurable, high speed data acquisition and processing system. The radar modes currently implemented include scatterometer, synthetic aperture radar, and altimetry; and plans to add new modes such as radiometry and bi-static GNSS signals are being formulated. This development is aimed at enhancing the radar remote sensing capabilities for airborne and spaceborne applications in support of Earth Science and planetary exploration This paper describes the design of the radar and processor systems, explains the operational modes, and discusses preliminary measurements and future plans.

  5. 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 alcohol...

  6. 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 alcohol...

  7. 21 CFR 172.230 - Microcapsules for flavoring substances.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... of the following components: component and 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... coacervate of gum arabic and gelatin. n-Octyl alcohol—As a defoamer. (4) In lieu of the components listed in...

  8. 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...

  9. 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...

  10. The prolonged release of oxytetracycline hydrochloride from ethylcellulose microcapsules.

    PubMed

    Mesiha, M S; Aboutaleb, A E

    1982-07-01

    Oxytetracycline hydrochloride microcapsules were prepared by separation of ethylcellulose from cyclohexane solution following cooling. Incomplete release was found when testing the dissolution rate in water. Interaction of the polymer with oxytetracycline was elucidated by IR spectroscopy. More release of the drug in water agreed with the diffusional model, but in acid it was more complex.

  11. Temperature-Adaptive Circuits on Reconfigurable Analog Arrays

    NASA Technical Reports Server (NTRS)

    Stoica, Adrian; Zebulum, Ricardo S.; Keymeulen, Didier; Ramesham, Rajeshuni; Neff, Joseph; Katkoori, Srinivas

    2006-01-01

    Demonstration of a self-reconfigurable Integrated Circuit (IC) that would operate under extreme temperature (-180 C and 120 C) and radiation (300krad), without the protection of thermal controls and radiation shields. Self-Reconfigurable Electronics platform: a) Evolutionary Processor (EP) to run reconfiguration mechanism; b) Reconfigurable chip (FPGA, FPAA, etc).

  12. Quality evaluation of peony seed oil spray-dried in different combinations of wall materials during encapsulation and storage.

    PubMed

    Shi, Yan; Wang, Shu-Jie; Tu, Zong-Cai; Wang, Hui; Li, Ru-Yi; Zhang, Lu; Huang, Tao; Su, Ting; Li, Cui

    2016-06-01

    This study aimed at evaluating the performance of peony seed oil microencapsulated by spray drying during encapsulation and storage. Four different combinations of gum arabic (GA), corn syrup (CS), whey protein concentrate (WPC) and sodium caseinate (CAS) were used to encapsulate peony seed oil. The best encapsulation efficiency was obtained for CAS/CS followed by the CAS/GA/CS combination with the encapsulation ratio of 93.71 and 92.80 %, respectively, while the lowest encapsulation efficiency was obtained for WPC/GA/CS (85.96 %). Scanning electron microscopy and confocal laser scanning microscopy revealed that the particles were spherical in shape and did not exhibit apparent cracks or fissures, and gum arabic was uniformly distributed across the wall of the microcapsules. Oxidative stability study indicated that the CAS/GA/CS combination presented the best protection against lipid oxidation and the smallest loss of polyunsaturated fatty acid content among all of the formulas as measured by gas chromatography. Therefore, CAS/GA/CS could be promising materials encapsulate peony seed oil with high encapsulation efficiency and minimal lipid oxidation.

  13. Radiation effects in reconfigurable FPGAs

    NASA Astrophysics Data System (ADS)

    Quinn, Heather

    2017-04-01

    Field-programmable gate arrays (FPGAs) are co-processing hardware used in image and signal processing. FPGA are programmed with custom implementations of an algorithm. These algorithms are highly parallel hardware designs that are faster than software implementations. This flexibility and speed has made FPGAs attractive for many space programs that need in situ, high-speed signal processing for data categorization and data compression. Most commercial FPGAs are affected by the space radiation environment, though. Problems with TID has restricted the use of flash-based FPGAs. Static random access memory based FPGAs must be mitigated to suppress errors from single-event upsets. This paper provides a review of radiation effects issues in reconfigurable FPGAs and discusses methods for mitigating these problems. With careful design it is possible to use these components effectively and resiliently.

  14. Dynamically Reconfigurable Systolic Array Accelerator

    NASA Technical Reports Server (NTRS)

    Dasu, Aravind; Barnes, Robert

    2012-01-01

    A polymorphic systolic array framework has been developed that works in conjunction with an embedded microprocessor on a field-programmable gate array (FPGA), which allows for dynamic and complimentary scaling of acceleration levels of two algorithms active concurrently on the FPGA. Use is made of systolic arrays and a hardware-software co-design to obtain an efficient multi-application acceleration system. The flexible and simple framework allows hosting of a broader range of algorithms, and is extendable to more complex applications in the area of aerospace embedded systems. FPGA chips can be responsive to realtime demands for changing applications needs, but only if the electronic fabric can respond fast enough. This systolic array framework allows for rapid partial and dynamic reconfiguration of the chip in response to the real-time needs of scalability, and adaptability of executables.

  15. Reconfigurable optical assembly of nanostructures

    NASA Astrophysics Data System (ADS)

    Montelongo, Yunuen; Yetisen, Ali K.; Butt, Haider; Yun, Seok-Hyun

    2016-06-01

    Arrangements of nanostructures in well-defined patterns are the basis of photonic crystals, metamaterials and holograms. Furthermore, rewritable optical materials can be achieved by dynamically manipulating nanoassemblies. Here we demonstrate a mechanism to configure plasmonic nanoparticles (NPs) in polymer media using nanosecond laser pulses. The mechanism relies on optical forces produced by the interference of laser beams, which allow NPs to migrate to lower-energy configurations. The resulting NP arrangements are stable without any external energy source, but erasable and rewritable by additional recording pulses. We demonstrate reconfigurable optical elements including multilayer Bragg diffraction gratings, volumetric photonic crystals and lenses, as well as dynamic holograms of three-dimensional virtual objects. We aim to expand the applications of optical forces, which have been mostly restricted to optical tweezers. Holographic assemblies of nanoparticles will allow a new generation of programmable composites for tunable metamaterials, data storage devices, sensors and displays.

  16. Reconfigurable optical assembly of nanostructures.

    PubMed

    Montelongo, Yunuen; Yetisen, Ali K; Butt, Haider; Yun, Seok-Hyun

    2016-06-23

    Arrangements of nanostructures in well-defined patterns are the basis of photonic crystals, metamaterials and holograms. Furthermore, rewritable optical materials can be achieved by dynamically manipulating nanoassemblies. Here we demonstrate a mechanism to configure plasmonic nanoparticles (NPs) in polymer media using nanosecond laser pulses. The mechanism relies on optical forces produced by the interference of laser beams, which allow NPs to migrate to lower-energy configurations. The resulting NP arrangements are stable without any external energy source, but erasable and rewritable by additional recording pulses. We demonstrate reconfigurable optical elements including multilayer Bragg diffraction gratings, volumetric photonic crystals and lenses, as well as dynamic holograms of three-dimensional virtual objects. We aim to expand the applications of optical forces, which have been mostly restricted to optical tweezers. Holographic assemblies of nanoparticles will allow a new generation of programmable composites for tunable metamaterials, data storage devices, sensors and displays.

  17. Reconfigurable optical assembly of nanostructures

    PubMed Central

    Montelongo, Yunuen; Yetisen, Ali K.; Butt, Haider; Yun, Seok-Hyun

    2016-01-01

    Arrangements of nanostructures in well-defined patterns are the basis of photonic crystals, metamaterials and holograms. Furthermore, rewritable optical materials can be achieved by dynamically manipulating nanoassemblies. Here we demonstrate a mechanism to configure plasmonic nanoparticles (NPs) in polymer media using nanosecond laser pulses. The mechanism relies on optical forces produced by the interference of laser beams, which allow NPs to migrate to lower-energy configurations. The resulting NP arrangements are stable without any external energy source, but erasable and rewritable by additional recording pulses. We demonstrate reconfigurable optical elements including multilayer Bragg diffraction gratings, volumetric photonic crystals and lenses, as well as dynamic holograms of three-dimensional virtual objects. We aim to expand the applications of optical forces, which have been mostly restricted to optical tweezers. Holographic assemblies of nanoparticles will allow a new generation of programmable composites for tunable metamaterials, data storage devices, sensors and displays. PMID:27337216

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

    PubMed

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

    2015-02-14

    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.

  19. Combined characterization of bovine polyhemoglobin microcapsules by UV-Vis absorption spectroscopy and cyclic voltammetry.

    PubMed

    Knirsch, Marcos Camargo; Dell'Anno, Filippo; Salerno, Marco; Larosa, Claudio; Polakiewicz, Bronislaw; Eggenhöffner, Roberto; Converti, Attilio

    2017-03-01

    Polyhemoglobin produced from pure bovine hemoglobin by reaction with PEG bis(N-succynimidil succinate) as a cross-linking agent was encapsulated in gelatin and dehydrated by freeze-drying. Free carboxyhemoglobin and polyhemoglobin microcapsules were characterized by UV-Vis spectroscopy in the absorption range 450-650 nm and cyclic voltammetry in the voltage range from -0.8 to 0.6 mV to evaluate the ability to break the bond with carbon monoxide and to study the carrier's affinity for oxygen, respectively. SEM used to observe the shape of cross-linked gelatin-polyhemoglobin microparticles showed a regular distribution of globular shapes, with mean size of ~750 nm, which was ascribed to gelatin. Atomic absorption spectroscopy was also performed to detect iron presence in microparticles. Cyclic voltammetry using an Ag-AgCl electrode highlighted characteristic peaks at around -0.6 mV that were attributed to reversible oxygen bonding with iron in oxy-polyhemoglobin structure. These results suggest this technique as a powerful, direct and alternative method to evaluate the extent of hemoglobin oxygenation.

  20. Preparation of microcapsules by complex coacervation of gum Arabic and chitosan.

    PubMed

    Butstraen, Chloé; Salaün, Fabien

    2014-01-01

    Gum Arabic-chitosan microcapsules containing a commercially available blend of triglycerides (Miglyol 812 N) as core phase were synthesized by complex coacervation. This study was conducted to clarify the influence of different parameters on the encapsulation process, i.e. during the emulsion formation steps and during the shell formation, using conductometry, zeta potential, surface and interface tension measurement and Fourier-transform infrared spectroscopy. By carefully analyzing the influencing factors including phase volume ratio, stirring rate and time, pH, reaction time, biopolymer ratio and crosslinking effect, the optimum synthetic conditions were found out. For the emulsion step, the optimum phase volume ratio chosen was 0.10 and an emulsion time of 15 min at 11,000 rpm was selected. The results also indicated that the optimum formation of these complexes appears at a pH value of 3.6 and a weight ratio of chitosan to gum Arabic mixtures of 0.25. Copyright © 2013 Elsevier Ltd. All rights reserved.

  1. Complex coacervate microcapsules for mammalian cell culture and artificial organ development.

    PubMed

    Matthew, H W; Salley, S O; Peterson, W D; Klein, M D

    1993-01-01

    A number of combinations of anionic and cationic polymers, the majority being polysaccharides, were screened to determine their suitability for the development of alternative microcapsule formulations capable of supporting cells. The capsules were taken through a limited optimization and then evaluated on the bases of rupture strength, permeability to albumin, and ability of their components to promote the attachment, aggregation, and function of encapsulated rabbit hepatocytes. The widely used alginate-polylysine capsules were employed as a comparative standard in all tests. A number of the new formulations compared favorably with the standard, and some exhibited superior performance in specific areas. Hepatocyte function, as evaluated by the rate of urea synthesis, showed no significant differences between formulations over a 24-h test period. One formulation, composed of the polysaccharides (carboxymethyl)cellulose, chondroitin sulfate A, chitosan, and polygalacturonate, was found to be superior to alginate-polylysine capsules in the areas investigated and supported the long-term survival and growth of liver endothelial cells.

  2. One-step synthesis of natural silk sericin-based microcapsules with bionic structures.

    PubMed

    Liu, Zhaogang; Cai, Yurong; Jia, Yaru; Liu, Lin; Kong, Xiangdong; Kundu, Subhas C; Yao, Juming

    2014-10-01

    Different techniques are being developed for fabricating microcapsules; it is still a challenge to fabricate them in an efficient and environment-friendly process. Here, a one-step green route to synthesize silk protein sericin-based microcapsules without any assistance of organic solvents is reported. By carefully changing the concentration of calcium ions accompanied with stirring, the morphology of the microcapsules can easily be regulated to form either discoidal, biconcave, cocoon-like, or tubular structures. The chelation of Ca(2+) and shearing force from agitation may induce the conformational transformation of sericin, which possibly results in the formation of microcapsules through the self-assembly of the protein subsequently. The as-prepared cocoon-like microcapsules exhibit pH-dependent stability. A potential application of microcapsules being fabricated from natural water-soluble silk protein sericin for controlled bioactive molecules loading and release system by a pH-triggered manner is quite feasible.

  3. Encapsulated human primary myoblasts deliver functional hFIX in hemophilic mice.

    PubMed

    Wen, Jianping; Xu, Nong; Li, Anna; Bourgeois, Jacqueline; Ofosu, Frederick A; Hortelano, Gonzalo

    2007-11-01

    Hemophilia B is a bleeding disorder caused by defective factor IX (FIX), currently treated by regular infusions of plasma-derived or recombinant FIX. We propose a gene therapy strategy based on the implantation of cells secreting FIX enclosed in alginate microcapsules as a highly desirable alternative treatment. We have reported sustained delivery of human factor IX (hFIX) in immunocompetent mice implanted with encapsulated primary mouse myoblasts engineered to secrete hFIX. As a step towards the treatment of human patients, in this study we report the implantation of encapsulated human primary myoblasts secreting hFIX in hemophilia B mice. Human primary myoblasts were transfected with plasmids pKL4M-hFIX, pLNM-betaIXL, pMFG-hFIX, and transduced with retrovirus MFG-hFIX. Two human primary myoblast clones secreting approximately 1 microg hFIX/10(6) cells/day were enclosed in biocompatible alginate microcapsules and implanted intraperitoneally into SCID and hemophilic mice. Circulating hFIX (peak of approximately 120 ng/ml) was detected in hemophilia B mice on day 1 after implantation. Human FIX delivery was transient, however, becoming undetectable on day 14. Concurrently, anti-hFIX antibodies were detected. At the same time, activated partial thromboplastin time (APTT) was reduced from 94 s before treatment to 78-80 s. Tail bleeding time decreased from 15 min to 1.5-7 min after treatment, some mice being normalised. These findings indicate that the delivered hFIX is biologically active. Similarly treated NOD/SCID mice had circulating hFIX levels of 170 ng/ml on day 1 that remained detectable for 1 month, albeit at low levels. Cell viability of microcapsules retrieved on day 60 was below 5%. Our findings indicate that encapsulated human primary myoblasts secrete functional hFIX. Furthermore, implantation of encapsulated human primary myoblasts can partially correct the phenotype of hemophilia B mice, supporting the feasibility of this gene therapy approach for

  4. Immune responses to an encapsulated allogeneic islet {beta}-cell line in diabetic NOD mice

    SciTech Connect

    Black, Sasha P. . E-mail: Sasha.Black@ca.crl.com; Constantinidis, Ioannis; Cui, Hong; Tucker-Burden, Carol; Weber, Collin J.; Safley, Susan A.

    2006-02-03

    Our goal is to develop effective islet grafts for treating type 1 diabetes. Since human islets are scarce, we evaluated the efficacy of a microencapsulated insulin-secreting conditionally transformed allogeneic {beta}-cell line ({beta}TC-tet) in non-obese diabetic mice treated with tetracycline to inhibit cell growth. Relatively low serum levels of tetracycline controlled proliferation of {beta}TC-tet cells without inhibiting effective control of hyperglycemia in recipients. There was no significant host cellular reaction to the allografts or host cell adherence to microcapsules, and host cytokine levels were similar to those of sham-operated controls. We conclude that encapsulated allogeneic {beta}-cell lines may be clinically relevant, because they effectively restore euglycemia and do not elicit a strong cellular immune response following transplantation. To our knowledge, this is First extensive characterization of the kinetics of host cellular and cytokine responses to an encapsulated islet cell line in an animal model of type 1 diabetes.

  5. Encapsulation of vegetable oils as source of omega-3 fatty acids for enriched functional foods.

    PubMed

    Ruiz Ruiz, Jorge Carlos; Ortiz Vazquez, Elizabeth De La Luz; Segura Campos, Maira Rubi

    2017-05-03

    Polyunsaturated omega-3 fatty acids (PUFAs), a functional component present in vegetable oils, are generally recognized as being beneficial to health. Omega-3 PUFAs are rich in double bonds and unsaturated in nature; this attribute makes them highly susceptible to lipid oxidation and unfit for incorporation into long shelf life foods. The microencapsulation of oils in a polymeric matrix (mainly polysaccharides) offers the possibility of controlled release of the lipophilic functional ingredient and can be useful for the supplementation of foods with PUFAs. The present paper provides a literature review of different vegetable sources of omega-3 fatty acids, the functional effects of omega-3 fatty acids, different microencapsulation methods that can possibly be used for the encapsulation of oils, the properties of vegetable oil microcapsules, the effect of encapsulation on oxidation stability and fatty acid composition of vegetable oils, and the incorporation of long-chain omega-3 polyunsaturated fatty acids in foods.

  6. Adaptive reconfigurable distributed sensor architecture

    NASA Astrophysics Data System (ADS)

    Akey, Mark L.

    1997-07-01

    The infancy of unattended ground based sensors is quickly coming to an end with the arrival of on-board GPS, networking, and multiple sensing capabilities. Unfortunately, their use is only first-order at best: GPS assists with sensor report registration; networks push sensor reports back to the warfighter and forwards control information to the sensors; multispectral sensing is a preset, pre-deployment consideration; and the scalability of large sensor networks is questionable. Current architectures provide little synergy among or within the sensors either before or after deployment, and do not map well to the tactical user's organizational structures and constraints. A new distributed sensor architecture is defined which moves well beyond single sensor, single task architectures. Advantages include: (1) automatic mapping of tactical direction to multiple sensors' tasks; (2) decentralized, distributed management of sensor resources and tasks; (3) software reconfiguration of deployed sensors; (4) network scalability and flexibility to meet the constraints of tactical deployments, and traditional combat organizations and hierarchies; and (5) adaptability to new battlefield communication paradigms such as BADD (Battlefield Analysis and Data Dissemination). The architecture is supported in two areas: a recursive, structural definition of resource configuration and management via loose associations; and a hybridization of intelligent software agents with tele- programming capabilities. The distributed sensor architecture is examined within the context of air-deployed ground sensors with acoustic, communication direction finding, and infra-red capabilities. Advantages and disadvantages of the architecture are examined. Consideration is given to extended sensor life (up to 6 months), post-deployment sensor reconfiguration, limited on- board sensor resources (processor and memory), and bandwidth. It is shown that technical tasking of the sensor suite can be automatically

  7. Reconfigurable Complementary Monolayer MoTe2 Field-Effect Transistors for Integrated Circuits.

    PubMed

    Larentis, Stefano; Fallahazad, Babak; Movva, Hema C P; Kim, Kyounghwan; Rai, Amritesh; Taniguchi, Takashi; Watanabe, Kenji; Banerjee, Sanjay K; Tutuc, Emanuel

    2017-05-23

    Transition metal dichalcogenides are of interest for next generation switches, but the lack of low resistance electron and hole contacts in the same material has hindered the development of complementary field-effect transistors and circuits. We demonstrate an air-stable, reconfigurable, complementary monolayer MoTe2 field-effect transistor encapsulated in hexagonal boron nitride, using electrostatically doped contacts. The introduction of a multigate design with prepatterned bottom contacts allows us to independently achieve low contact resistance and threshold voltage tuning, while also decoupling the Schottky contacts and channel gating. We illustrate a complementary inverter and a p-i-n diode as potential applications.

  8. Influence of emulsifying agents on the properties of cellulose acetate butyrate and ethylcellulose microcapsules.

    PubMed

    Kristmundsdóttir, T; Ingvarsdóttir, K

    1994-01-01

    Microcapsules of ibuprofen were prepared according to the solvent evaporation method, using two coating polymers, cellulose acetate butyrate and ethylcellulose. The influence of two emulsifying agents, polysorbat 80 and polyvinyl alcohol, on the properties of the microcapsules was investigated. The results show that type and concentration of emulsifying agent influences size distribution, drug loading and amount of free drug on the surface of the microcapsules.

  9. Fabrication of Novel Types of Colloidosome Microcapsules for Drug Delivery Applications

    DTIC Science & Technology

    2005-01-01

    UNCLASSIFIED Defense Technical Information Center Compilation Part Notice ADP019733 TITLE: Fabrication of Novel Types of Colloidosome Microcapsules ...UNCLASSIFIED Mater. Res. Soc. Symp. Proc. Vol. 845 © 2005 Materials Research Society AA5.18 Fabrication of Novel Types of Colloidosome Microcapsules for Drug...Novel colloidosome microcapsules with aqueous gel cores and shells of different polymeric colloid particles have been prepared and characterized. Our

  10. Review of encapsulation technologies

    SciTech Connect

    Shaulis, L.

    1996-09-01

    The use of encapsulation technology to produce a compliant waste form is an outgrowth from existing polymer industry technology and applications. During the past 12 years, the Department of Energy (DOE) has been researching the use of this technology to treat mixed wastes (i.e., containing hazardous and radioactive wastes). The two primary encapsulation techniques are microencapsulation and macroencapsulation. Microencapsulation is the thorough mixing of a binding agent with a powdered waste, such as incinerator ash. Macroencapsulation coats the surface of bulk wastes, such as lead debris. Cement, modified cement, and polyethylene are the binding agents which have been researched the most. Cement and modified cement have been the most commonly used binding agents to date. However, recent research conducted by DOE laboratories have shown that polyethylene is more durable and cost effective than cements. The compressive strength, leachability, resistance to chemical degradation, etc., of polyethylene is significantly greater than that of cement and modified cement. Because higher waste loads can be used with polyethylene encapsulant, the total cost of polyethylene encapsulation is significantly less costly than cement treatment. The only research lacking in the assessment of polyethylene encapsulation treatment for mixed wastes is pilot and full-scale testing with actual waste materials. To date, only simulated wastes have been tested. The Rocky Flats Environmental Technology Site had planned to conduct pilot studies using actual wastes during 1996. This experiment should provide similar results to the previous tests that used simulated wastes. If this hypothesis is validated as anticipated, it will be clear that polyethylene encapsulation should be pursued by DOE to produce compliant waste forms.

  11. Potential of Alginate Encapsulated Ferric Saccharate Microemulsions to Ameliorate Iron Deficiency in Mice.

    PubMed

    Mukhija, Kimmi; Singhal, Kirti; Angmo, Stanzin; Yadav, Kamalendra; Yadav, Hariom; Sandhir, Rajat; Singhal, Nitin Kumar

    2016-07-01

    Iron deficiency is one of the most prominent mineral deficiencies around the world, which especially affects large population of women and children. Development of new technologies to combat iron deficiency is on high demand. Therefore, we developed alginate microcapsule with encapsulated iron that had better oral iron bioavailability. Microcapsules containing iron with varying ratios of sodium alginate ferric(III)-saccharide were prepared using emulsification method. In vitro studies with Caco-2 cells suggested that newly synthesized microemulsions had better iron bioavailability as compared to commercially available iron dextran formulations. Ferrozine in vitro assay showed that alginate-encapsulated ferric galactose microemulsion (AFGM) had highest iron bioavailability in comparison to other four ferric saccharate microemulsions, namely AFGlM, AFMM, AFSM, and AFFM synthesized in our laboratory. Mice studies also suggested that AFGM showed higher iron absorption as indicated by increased serum iron, hemoglobin, and other hematopoietic measures with almost no toxicity at tested doses. Development of iron-loaded microemulsions leads to higher bioavailability of iron and can provide alternative strategies to treat iron deficiency.

  12. GPC-Based Stable Reconfigurable Control

    NASA Technical Reports Server (NTRS)

    Soloway, Don; Shi, Jian-Jun; Kelkar, Atul

    2004-01-01

    This paper presents development of multi-input multi-output (MIMO) Generalized Pre-dictive Control (GPC) law and its application to reconfigurable control design in the event of actuator saturation. A Controlled Auto-Regressive Integrating Moving Average (CARIMA) model is used to describe the plant dynamics. The control law is derived using input-output description of the system and is also related to the state-space form of the model. The stability of the GPC control law without reconfiguration is first established using Riccati-based approach and state-space formulation. A novel reconfiguration strategy is developed for the systems which have actuator redundancy and are faced with actuator saturation type failure. An elegant reconfigurable control design is presented with stability proof. Several numerical examples are presented to demonstrate the application of various results.

  13. Reconfigurable materials: Algorithm for architectural origami

    NASA Astrophysics Data System (ADS)

    Paik, Jamie

    2017-01-01

    An algorithm has been developed allowing the rational design of origami-inspired materials that can be rearranged to change their properties. This might open the way to strategies for making reconfigurable robots. See Article p.347

  14. Surface modification of self-healing poly(urea-formaldehyde) microcapsules using silane-coupling agent

    NASA Astrophysics Data System (ADS)

    Li, Haiyan; Wang, Rongguo; Hu, Honglin; Liu, Wenbo

    2008-12-01

    Poly(urea-formaldehyde) (PUF) microcapsules, which are used as self-healing component of fibre reinforced resin matrix composites, were prepared by in situ polymerization method. The surface of PUF microcapsules was modified by using 3-aminopropyltriethoxy silane-coupling agent (KH550), and the interfacial interactions between PUF microcapsules and KH550 was also studied. Fourier transform infrared spectra (FT-IR) and X-ray photoelectron spectra (XPS) analyses showed that the silane-coupling agent molecular binds strongly to PUF microcapsules surface. Chemical bond (Si-O-C) was formed by the reaction between Si-OH and the hydroxyl group of PUF microcapsules, also there have chemical adsorption effect in the interface simultaneously because of the existence of hydrogen bond between Si-OH and the hydroxyl group of PUF microcapsules. Scanning electronic microscopy (SEM) observation showed that a thin layer was formed on the surface of modified PUF microcapsules. Additionally, fractured surface were observed under SEM to investigate the interfacial adhesion effect between PUF microcapsules and epoxy matrix. The result indicted that the silane-coupling agent play an important role in improving the interfacial performance between microcapsules and resin matrix.

  15. Enhanced performance of lipase via microcapsulation and its application in biodiesel preparation

    PubMed Central

    Su, Feng; Li, Guanlin; Fan, Yanli; Yan, Yunjun

    2016-01-01

    In the present study, a surface-active enzyme, lipase was immobilized in polyethyleneimine (PEI) microcapsules and then modified with oxidized multiwall carbon nanotubes (MWCNTs). The resulting lipase microcapsules exhibited higher activity and stability, since the activity of microcapsules was 21.9 folds than that of the free counterpart. Numerous interfaces which were created in polycondensation enhanced the performance of lipases. Illustrated by confocal laser scanning microscope (CLSM), it was found that microcapsules, whose barrier properties against molecules with diameter >4.6 nm, were with a semipermeable and porous membrane structure. The lipases preferred to locate in the wall of the microcapsules. The oxidized multiwall carbon nanotubes (MWCNTs) were further added to modify microcapsules, resulting in even higher activity. The nanocomposites were examined by scanning electron microscope (SEM) and zeta-potential analyzer. The results indicated the superior catalytic performances were attributed to the augmented interface and decreased positive charge. Finally, the MWCNTs modified microcapsules were utilized in producing biodiesel with a 97.15% yield and retained nearly 90% yield after running 10 cycles. This approach of microcapsulation will be highly beneficial for preparing various bio-active microcapsules with excellent catalytic performance. PMID:27424490

  16. In situ fabrication and electrochemical behavior of amino acid polyoxometalate nanoparticles-embedded microcapsules.

    PubMed

    Fan, Dawei; Deng, Yongming; Hao, Jingcheng

    2010-11-01

    Amino acid polyoxometalate nanoparticles-embedded microcapsules were in situ fabricated by layer-by-layer (LbL) self-assembly method [polyoxometalate, H3PMo12O40·nH2O (PMo12); amino acid, glycine (Gly)]. The morphology of the obtained microcapsules was characterized by transmission electron microscopy and scanning electron microscopy. The electrochemical behavior of the amino acid polyoxometalate nanoparticles-embedded microcapsules was studied by cyclic voltammetry. The microcapsules show the pH-dependent properties, indicating that the pH of solution plays an important role in the electrochemical behavior of heteropolyanions.

  17. Local and Sustained Activity of Doxycycline Delivered with Layer-by-Layer Microcapsules.

    PubMed

    Luo, Dong; Gould, David J; Sukhorukov, Gleb B

    2016-04-11

    Achieving localized delivery of small molecule drugs has the potential to increase efficacy and reduce off target and side effects associated with systemic distribution. Herein, we explore the potential use of layer-by-layer (LbL) assembled microcapsules for the delivery of doxycycline. Absorbance of doxycycline onto core dextran sulfate of preassembled microcapsules provides an efficient method to load both synthetic and biodegradable microcapsules with the drug. Application of an outer layer lipid coat enhances the sustained in vitro release of doxycycline from both microcapsule types. To monitor doxycycline delivery in a biological system, C2C12 mouse myoblasts are engineered to express EGFP under the control of the optimized components of the tetracycline regulated gene expression system. Microcapsules are not toxic to these cells, and upon delivery to the cells, EGFP is more efficiently induced in those cells that contain engulfed microcapsules and monitored EGFP expression clearly demonstrates that synthetic microcapsules with a DPPC coat are the most efficient for sustain intracellular delivery. Doxycycline released from microcapsules also displayed sustained activity in an antimicrobial growth inhibition assay compared with doxycycline solution. This study reveals the potential for LbL microcapsules in small molecule drug delivery and their feasible use for achieving prolonged doxycycline activity.

  18. Encapsulation materials research

    NASA Technical Reports Server (NTRS)

    Willis, P. B.

    1984-01-01

    Encapsulation materials for solar cells were investigated. The different phases consisted of: (1) identification and development of low cost module encapsulation materials; (2) materials reliability examination; and (3) process sensitivity and process development. It is found that outdoor photothermal aging devices (OPT) are the best accelerated aging methods, simulate worst case field conditions, evaluate formulation and module performance and have a possibility for life assessment. Outdoor metallic copper exposure should be avoided, self priming formulations have good storage stability, stabilizers enhance performance, and soil resistance treatment is still effective.

  19. Stretchability of encapsulated electronics

    NASA Astrophysics Data System (ADS)

    Wu, J.; Liu, Z. J.; Song, J.; Huang, Y.; Hwang, K.-C.; Zhang, Y. W.; Rogers, J. A.

    2011-08-01

    Stretchable and flexible electronics offer the performance of conventional wafer-based systems but can be stretched like a rubber band, twisted like a rope, and bent over a pencil. Such a technology offers new application opportunities, in areas of surgical and diagnostic implements that naturally integrate with the human body to provide advanced capabilities, to curvilinear devices such as hemispherical "eyeball" cameras. In practice, stretchable and flexible electronic systems require encapsulation layers to provide mechanical and environmental protection. This paper establishes a simple, analytical model for the optimal design of encapsulation.

  20. Microencapsulation of borage oil with blends of milk protein, β-glucan and maltodextrin through spray drying: physicochemical characteristics and stability of the microcapsules.

    PubMed

    Li, Ru-Yi; Shi, Yan

    2017-07-07

    Borage oil is a rich commercial source of γ-linolenic acid (18:3n-6). However, borage oil is rich in omega-6 polyunsaturated fatty acids and vulnerable to oxidation. Thus, selecting appropriate wall materials is critical to the encapsulation of borage oil. The present study investigated the influence of wall materials on the physicochemical characteristics and stability of microencapsulated borage oil by spray drying. Blends of milk protein [sodium caseinate (CAS) or whey protein concentrate], β-glucan (GLU) and maltodextrin (MD) were used as the wall materials for encapsulating borage oil. The microencapsulation of borage oil with different wall materials attained high encapsulation efficiencies. The microencapsulated borage oil prepared with CAS-MD achieved the optimal encapsulation efficiency of 96.62%. The oxidative stabilities of borage oil and microencapsulated borage oil were measured by accelerated storage test at 45 °C and 33% relative humidity for 30 days. The microencapsulated borage oil presented lower peroxide values than those of borage oil, and the microcapsules prepared with CAS-10GLU-MD (consisting of CAS 50 g kg(-1) , GLU 100 g kg(-1) and MD 475 g kg(-1) of microencapsulation) conferred borage oil with high protection against lipid oxidation. The results of the present study demonstrate that the CAS-GLU-MD blend is appropriate for microencapsulating borage oil. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

  1. RF MEMS reconfigurable triangular patch antenna.

    SciTech Connect

    Nordquist, Christopher Daniel; Christodoulou, Christos George; Feldner, Lucas Matthew

    2005-01-01

    A Ka-band RF MEMS enabled frequency reconfigurable triangular microstrip patch antenna has been designed for monolithic integration with RF MEMS phase shifters to demonstrate a low-cost monolithic passive electronically scanned array (PESA). This paper introduces our first prototype reconfigurable triangular patch antenna currently in fabrication. The aperture coupled patch antenna is fabricated on a dual-layer quartz/alumina substrate using surface micromachining techniques.

  2. RF MEMS reconfigurable triangular patch antenna.

    SciTech Connect

    Christodoulou, Christos George; Nordquist, Christopher Daniel; Feldner, Lucas Matthew

    2005-07-01

    A Ka-band RF MEMS enabled frequency reconfigurable triangular microstrip patch antenna has been designed for monolithic integration with RF MEMS phase shifters to demonstrate a low-cost monolithic passive electronically scanned array (PESA). This paper introduces our first prototype reconfigurable triangular patch antenna currently in fabrication. The aperture coupled patch antenna is fabricated on a dual-layer quartz/alumina substrate using surface micromachining techniques.

  3. An FPGA-based reconfigurable DDC algorithm

    NASA Astrophysics Data System (ADS)

    Juszczyk, B.; Kasprowicz, G.

    2016-09-01

    This paper describes implementation of reconfigurable digital down converter in an FPGA structure. System is designed to work with quadrature signals. One of the main criteria of the project was to provied wide range of reconfiguration in order to fulfill various application rage. Potential applications include: software defined radio receiver, passive noise radars and measurement data compression. This document contains general system overview, short description of hardware used in the project and gateware implementation.

  4. Stability and loading properties of curcumin encapsulated in Chlorella vulgaris.

    PubMed

    Jafari, Yaser; Sabahi, Hossein; Rahaie, Mahdi

    2016-11-15

    Curcumin (Cur), a polyphenols with pharmacological function, was successfully encapsulated in algae (Alg) cell (Chlorella vulgaris) as confirmed by fluorescence microscopy, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and Fourier transform-infrared spectroscopy (FT-IR). Fluorescence micrographs, TGA, DSC and FTIR spectra suggested the hypothesis inclusion Cur in Nano-empty spaces inside cell wall of Alg. The TGA analysis showed that the thermal stability of Alg and Cur at algae/curcumin complex was 3.8% and 33% higher than their free forms at 0-300°C and 300-600°C ranges, respectively. After encapsulation in Alg cells, the photostability of Cur was enhanced by about 2.5-fold. Adsorption isotherm of Cur into Alg was fitted with the Freundlich isotherm. The microcapsules were loaded with Cur up to about 55% w/w which is much higher than other reported bio-carriers. In conclusion, the data proved that Chlorella vulgaris cell can be used as a new stable carrier for Cur.

  5. Enhanced function of immuno-isolated islets in diabetes therapy by co-encapsulation with an anti-inflammatory drug

    PubMed Central

    Dang, Tram T.; Thai, Anh V.; Cohen, Joshua; Slosberg, Jeremy E.; Siniakowicz, Karolina; Doloff, Joshua C.; Ma, Minglin; Hollister-Lock, Jennifer; Tang, Katherine; Gu, Zhen; Cheng, Hao; Weir, Gordon C.; Langer, Robert; Anderson, Daniel G.

    2013-01-01

    Immuno-isolation of islets has the potential to enable the replacement of pancreatic function in diabetic patients. However, host response to the encapsulated islets frequently leads to fibrotic overgrowth with subsequent impairment of the transplanted grafts. Here, we identified and incorporated anti-inflammatory agents into islet-containing microcapsules to address this challenge. In vivo subcutaneous screening of 16 small molecule anti-inflammatory drugs was performed to identify promising compounds that could minimize the formation of fibrotic cell layers. Using parallel non-invasive fluorescent and bioluminescent imaging, we identified dexamethasone and curcumin as the most effective drugs in inhibiting the activities of inflammatory proteases and reactive oxygen species in the host response to subcutaneously injected biomaterials. Next, we demonstrated that co-encapsulating curcumin with pancreatic rat islets in alginate microcapsules reduced fibrotic overgrowth and improved glycemic control in a mouse model of chemically-induced type I diabetes. These results showed that localized administration of anti-inflammatory drug can improve the longevity of encapsulated islets and may facilitate the translation of this technology towards a long-term cure for type I diabetes. PMID:23660251

  6. Encapsulation materials research

    NASA Technical Reports Server (NTRS)

    Willis, P.

    1985-01-01

    The successful use of outdoor mounting racks as an accelerated aging technique (these devices are called optal reactors); a beginning list of candidate pottant materials for thin-film encapsulation, which process at temperatures well below 100 C; and description of a preliminary flame retardant formulation for ethylene vinyl acetate which could function to increase module flammability ratings are presented.

  7. Wet Winding Improves Coil Encapsulation

    NASA Technical Reports Server (NTRS)

    Hill, A. J.

    1987-01-01

    Wet-winding process encapsulates electrical coils more uniformily than conventional processes. Process requires no vacuum pump and adapts easily to existing winding machines. Encapsulant applied to each layer of wire as soon as added to coil. Wet-winding process eliminates voids, giving more uniformly encapsulated coil.

  8. A preliminary study of microcapsule suspension for hemolysis evaluation of artificial organs.

    PubMed

    Maruyama, O; Yamane, T; Tsunemoto, N; Nishida, M; Tsutsui, T; Jikuya, T

    1999-03-01

    A microcapsule suspension, a substitute for animal blood in hemolysis tests, has been developed for evaluation of the absolute hemolytic properties of circulatory artificial organs. The microcapsule suspension was made by dispersing microcapsule slurry into an ethylene glycol sodium chloride solution. The microcapsule slurry was composed of a leuco dye solution and polyurethane membrane made by the reaction between aliphatic poly-isocyanate and polyamine by interfacial polycondensation. The microcapsule was a small particle containing dye inside. The microcapsule suspension was white; the diameter of the microcapsules was from 5 to 100 microns. The specific gravity of the suspension was 1.024, and the membrane was elastic. The fluid showed Newtonian characteristics, different from animal blood, and its viscosity was approximately 5.8 mPa.s. After the microcapsules were destroyed, the leuco dye was extracted with n-hexane from the suspension and was measured by spectroscopy after being colored with acid ethanol. Hemolysis can be regarded as a fatigue fracture of cell membranes rather than a static fracture. The destruction of microcapsules by a Potter type tissue grinder was observed at a low stroke number region and was compared to rat blood. Moreover, hemolysis tests of a commercially available centrifugal blood pump and the prototype of our centrifugal pump for mechanism checks were carried out with bovine blood. The hemolysis level of the prototype pump increased with time while the hemolysis level of the commercial blood pump did not change as much as that of the control when both pumps were tested with the microcapsule suspension. These results are similar to tests utilizing bovine blood. Therefore, hemolysis tests of circulatory artificial organs completed with microcapsule suspension are expected to provide results similar to tests with animal blood.

  9. Enhanced Cellular Uptake of Bowl-like Microcapsules.

    PubMed

    Li, Huiying; Zhang, Wenbo; Tong, Weijun; Gao, Changyou

    2016-05-11

    Among several properties of colloidal particles, shape is emerging as an important parameter for tailoring the interactions between particles and cells. In this study, bowl-like multilayer microcapsules were prepared by osmotic-induced invagination of their spherical counterparts in a concentrated polyelectrolyte solution. The internalization behaviors of bowl-like and spherical microcapsules were compared by coincubation with smooth muscle cells (SMCs) and macrophages. The bowl-like capsules tended to attach onto the cell membranes from the bend side and could be enwrapped by the membranes of SMCs, leading to a faster uptake rate and larger accumulation inside cells than those of their spherical counterparts. These results are important for understanding the shape-dependent internalization behavior, providing useful guidance for further materials design especially in biomedical applications.

  10. Biomedical applications of polypeptide multilayer nanofilms and microcapsules

    NASA Astrophysics Data System (ADS)

    Rudra, Jai Simha S.

    The past few years have witnessed considerable growth in synthetic polymer chemistry and physics, biomaterials science, and nano-scale engineering. Research on polypeptide multilayer films, coatings, and microcapsules is located at the intersection of these areas and are promising materials for applications in medicine, biotechnology, environmental science. Most envisioned applications of polypeptide multilayers have a biomedical bent. This dissertation on polypeptide multilayer film applications covers key points of polypeptides as materials, means of polymer production, film preparation, film characterization methods, and key points of current research in basic science. Both commercial and designed peptides have been used to fabricate films for in-vitro applications such as antimicrobial coatings and cell culture coatings and also microcapsules for drug delivery applications. Other areas of product development include artificial red blood cells, anisotropic coatings, enantioselective membranes, and artificial viruses.

  11. A Dynamic Management Method for Fast Manufacturing Resource Reconfiguration

    NASA Astrophysics Data System (ADS)

    Yuan, Zhiye

    To fast and optimally reconfigure manufacturing resource, a dynamic management method for fast manufacturing resource reconfiguration based on holon was proposed. In this method, a dynamic management structure for fast manufacturing resource reconfiguration was established based on holon. Moreover, the cooperation relationship among holons for fast manufacturing resource reconfiguration and the manufacturing information cooperation mechanism based on holonic were constructed. Finally, the simulation system of a dynamic management method for fast manufacturing resource reconfiguration was demonstrated and validated by Flexsim software. It has shown the proposed method can dynamically and optimally reconfigure manufacturing resource, and it can effectively improve the efficiency of manufacturing processes.

  12. Reconfigurable visualization for HWIL simulation

    NASA Astrophysics Data System (ADS)

    Buford, James A., Jr.; Garcia, Tricia A.; Bowden, Mark H.

    1998-08-01

    The U.S. Army Aviation and Missile Command (AMCOM) Missile Research, Engineering, and Development Center (MRDEC) Advanced Simulation Center has recognized the need for re- configurable visualization in support of hardware-in-the- loop (HWIL) simulations. AMCOM MRDEC made the development of re-configurable visualization tools a priority. SimSight, developed at AMCOM MRDEC, is designed to provide 3D visualization to HWIL simulations and after action reviews. Leveraging both the latest hardware and software visual simulation technologies, SimSight displays a concise, 3D view of the simulated world providing the HWIL engineer with unprecedented power to analyze quickly the progress of a simulation from pre-launch to impact. Providing 3D visualization is only half the solution; data management, distribution, and analysis is the companion problem being dealt with by AMCOM MRDEC with the development of Fulcrum, a cross-platform data capture, distribution, analysis, and display framework of which SimSight will become a component.

  13. Nuclear Weapons Complex reconfiguration study

    SciTech Connect

    Not Available

    1991-01-01

    Shortly after assuming duties as Secretary of Energy, I reviewed the Nuclear Weapons Complex Modernization Report'' submitted to the Congress in January 1989 as required by the National Defense Authorization Act of 1988 and 1989. My review showed that several of the report's assumptions needed to be re-evaluated. During this eighteen-month review, dramatic world changes forced further reassessments of the future Nuclear Weapons Complex. These changes are reflected in the new report. The new report presents a plan to achieve a reconfigured complex, called Complex-21. Complex-21 would be smaller, less diverse, and less expensive to operated than the Complex of today. Complex-21 would be able to safely and reliability support nuclear deterrent stockpile objectives set forth by the President and funded by the Congress. It would be consistent with realities of the emerging international security environment and flexible enough to accommodate the likely range of deterrent contingencies. In addition, Complex-21 would be constructed and operated to comply with all applicable federal, state, and local laws, regulations, and orders. Achieving Complex-21 will require significant resources. This report provides and organized approach toward selecting the most appropriate configuration for Complex-21, satisfying environmental requirements, and minimizing costs. The alternative -- to continue to use piecemeal fixes to run an antiquated complex -- will be more expensive and provide a less reliable Nuclear Weapons Complex. As a consequence, implementation of the Complex-21 plan is considered necessary to ensure continued viability of our nuclear deterrent.

  14. Delivery of Vaccines by Biodegradable Polymeric Microcapsules with Bioadhesion Properties.

    DTIC Science & Technology

    1997-05-01

    Urease in Acid Protection for the Gastric Colonizing Bacteria Helicobacter Pylori and Helicobacter Felis," Sp. Nov., Microb. Ecol. Health Dis., 4, 121...SUBJECT TERMS D!,W QL iD ’ 15. NUMBER OF PAGES 35 Oral vaccines, bioadhesives, poly(lactic-co-glycolic) acid 16. PRICE CODE mucosal immunoloqy 17. SECURITY...Introduction Microspheres and microcapsules made of poly (D,L-lactic-co-glycolic acid ) (PLGA) have been investigated as vaccine delivery systems [Eldridge

  15. Sequential Release of Proteins from Structured Multishell Microcapsules.

    PubMed

    Shimanovich, Ulyana; Michaels, Thomas C T; De Genst, Erwin; Matak-Vinkovic, Dijana; Dobson, Christopher M; Knowles, Tuomas P J

    2017-09-07

    In nature, a wide range of functional materials is based on proteins. Increasing attention is also turning to the use of proteins as artificial biomaterials in the form of films, gels, particles, and fibrils that offer great potential for applications in areas ranging from molecular medicine to materials science. To date, however, most such applications have been limited to single component materials despite the fact that their natural analogues are composed of multiple types of proteins with a variety of functionalities that are coassembled in a highly organized manner on the micrometer scale, a process that is currently challenging to achieve in the laboratory. Here, we demonstrate the fabrication of multicomponent protein microcapsules where the different components are positioned in a controlled manner. We use molecular self-assembly to generate multicomponent structures on the nanometer scale and droplet microfluidics to bring together the different components on the micrometer scale. Using this approach, we synthesize a wide range of multiprotein microcapsules containing three well-characterized proteins: glucagon, insulin, and lysozyme. The localization of each protein component in multishell microcapsules has been detected by labeling protein molecules with different fluorophores, and the final three-dimensional microcapsule structure has been resolved by using confocal microscopy together with image analysis techniques. In addition, we show that these structures can be used to tailor the release of such functional proteins in a sequential manner. Moreover, our observations demonstrate that the protein release mechanism from multishell capsules is driven by the kinetic control of mass transport of the cargo and by the dissolution of the shells. The ability to generate artificial materials that incorporate a variety of different proteins with distinct functionalities increases the breadth of the potential applications of artificial protein-based materials

  16. [Study on the microstructure of fluorescent labelling ghee microcapsules by Tomoscan imaging].

    PubMed

    Shi, Yan; Zheng, Wei-wan; Zou, Jin; Zhang, Xue-chun; Liu, Fan

    2011-03-01

    In the present paper, fluorescein isothiocyanate was chosen as a fluorescence probe to mark casein protein in alkaline conditions. The interaction of the casein protein marked or not marked and fluorescein isothiocyanate was preliminarily discussed by the spectrum changes of UV-absorption and fluorescence spectrometry. Fluorescent marker was separated from SephadexG-50 chromatography column. With it as an emulsifier, the fluorescently-labeled ghee microcapsules were prepared by spray drying. And using laser scanning confocal microscope by tomoscan imaging to detect the microstructure of ghee microcapsules with the excitation of 488 nm argon-ion laser, the results showed that the casein protein assembled in the membrane surface of oil-water interface and microcapsules. The ghee microcapsules had two forms, namely mononuclear and multinuclear. The microcapsule was spherical. Its surface was smooth with no crack and no hollow. Its wall surface was intact and wall structure was relatively dense. The particle size showed obvious difference. Small particles attached to large particles, forming partial agglomerating powders to contribute to enhancing the solubility of microcapsules. These prove that the ghee microcapsule is an ideal microcapsule product.

  17. Silica-lipid hybrid microcapsules: influence of lipid and emulsifier type on in vitro performance.

    PubMed

    Lim, Li Hui; Tan, Angel; Simovic, Spomenka; Prestidge, Clive A

    2011-05-16

    This study reports on the physicochemical characterisation and in vitro investigations of macro-porous silica-lipid hybrid (SLH) microcapsules when formulated using various lipids: long-chain triglycerides (LCT), medium-chain triglycerides (MCT), medium-chain mono-, diglycerides (MCMDG); and emulsifiers: anionic lecithin and cationic oleylamine. For the lipophilic compound coumarin 102 (logP=4.09), a complete and immediate in vitro release was attained for the SLH microcapsules under simulated intestinal sink conditions. The in vitro digestion study of various types of SLH microcapsules demonstrates: (i) reduced variability and enhanced lipid digestibility for the MCMDG-based microcapsules (i.e. 90-100% lipolysis) in comparison with an equivalent lipid solution and emulsion (50-90% lipolysis); and (ii) more controllable digestion kinetics for the LCT-based microcapsules which produce a lipolysis rate higher than that of a lipid solution but lower than that of a lipid emulsion. The drug phase partition results show approximately 5- to 17-fold increase in the drug solubilisation degree resulting from the digestion of MCT and MCMDG-based microcapsules (116 μg/mL), and LCT-based microcapsules (416 μg/mL) in comparison with the blank micellar medium (24 μg/mL). In conclusion, the SLH microcapsules could be tailored to manipulate the digestion patterns of both medium- and long-chain lipids in order to maximise the drug solubilisation capacity. Copyright © 2011 Elsevier B.V. All rights reserved.

  18. Preparation of glucose-sensitive microcapsules with a porous membrane and functional gates.

    PubMed

    Chu, Liang-Yin; Liang, Yi-Jian; Chen, Wen-Mei; Ju, Xiao-Jie; Wang, Hai-Dong

    2004-08-15

    A glucose-sensitive microcapsule with a porous membrane and with linear-grafted polyacrylic acid (PAAC) chains and covalently bound glucose oxidase (GOD) enzymes in the membrane pores acting as functional gates was successfully prepared. Polyamide microcapsules with a porous membrane were prepared by interfacial polymerization, PAAC chains were grafted into the pores of the microcapsule membrane by plasma-graft pore-filling polymerization, and GOD enzymes were immobilized onto the PAAC-grafted microcapsules by a carbodiimide method. The release rates of model drug solutes from the fabricated microcapsules were significantly sensitive to the existence of glucose in the environmental solution. In solution, the release rate of either sodium chloride or VB(12) molecules from the microcapsules was low but increased dramatically in the presence of 0.2mol/L glucose. The prepared PAAC-grafted and GOD-immobilized microcapsules showed a reversible glucose-sensitive release characteristic. The proposed microcapsules provide a new mode for injection-type self-regulated drug delivery systems having the capability of adapting the release rate of drugs such as insulin in response to changes in glucose concentration, which is highly attractive for diabetes therapy.

  19. Ion permeable microcapsules for the release of biologically available ions for remineralization.

    PubMed

    Davidson, Michael T; Greving, Theresa A; McHale, William A; Latta, Mark A; Gross, Stephen M

    2012-03-01

    The objective of this study was to investigate the effect of chemical structure, ion concentration, and ion type on the release rate of biologically available ions useful for remineralization from microcapsules with ion permeable membranes. A heterogeneous polymerization technique was utilized to prepare microcapsules containing either an aqueous solution of K₂HPO₄, Ca(NO₃)₂, or NaF. Six different polyurethane-based microcapsule shells were prepared and characterized based on ethylene glycol, butanediol, hexanediol, octanediol, triethylene glycol, and bisphenol A structural units. Ion release profiles were measured as a function of initial ion concentration within the microcapsule, ion type, and microcapsule chemical structure. The rate of ion release increased with initial concentration of ion stored in the microcapsule over a range of 0.5-3.0M. The monomer used in the synthesis of the membrane had a significant effect on ion release rates at 3.0 M salt concentration. At 1.0 M, the ethylene glycol released ions significantly faster than the hexanediol-, octanediol-, and butanediol-based microcapsules. Ion release was fastest for fluoride and slowest for phosphate for the salts used in this study. It was concluded that the microcapsules are capable of releasing calcium, phosphate, and fluoride ions in their biologically available form.

  20. Development of valsartan-loaded gelatin microcapsule without crystal change using hydroxypropylmethylcellulose as a stabilizer.

    PubMed

    Li, Dong Xun; Yan, Yi Dong; Oh, Dong Hoon; Yang, Kwan Yeol; Seo, Yoon Gi; Kim, Jong Oh; Kim, Yong-Il; Yong, Chul Soon; Choi, Han-Gon

    2010-07-01

    To develop a valsartan-loaded gelatin microcapsule using hydroxypropylmethylcellulose (HPMC) as a stabilizer, which could improve the physical stability and bioavailability of valsartan, the gelatin microcapsules were prepared with various ratios of gelatin and HPMC using a spray-drying technique. Their solubility, dissolution, thermal characteristics, crystallinity, and physical stability were investigated. The bioavailability of drug in valsartan-loaded microcapsule was then evaluated compared to drug powder and commercial product in rats. The microcapsule with gelatin and/or HPMC enhanced the solubility and dissolution of drug compared to valsartan powder. Among the formulations tested, the valsartan-loaded gelatin microcapsule at the weight ratio of valsartan/gelatin/HPMC of 1/2/1 gave excellent drug solubility of approximately 2 microg/ml and dissolution of 70% at 1 h. The crystal state of valsartan in this microcapsule was changed from crystalline to amorphous form during the spray-drying process and maintained as an amorphous form at 40 degrees C for at least 3 months, indicating that it was physically stable. HPMC in this microcapsule could inhibit the recrystallization, resulting in stabilizing the amorphous form of valsartan. Furthermore, it improved the oral bioavailability of valsartan compared to valsartan powder and gave the similar AUC, C(max), and T(max) values to commercial product, suggesting that it was bioequivalent to commercial product in rats. Thus, the gelatin microcapsule with HPMC would be a more effective and stable oral delivery system of poorly water-soluble valsartan.

  1. Micromechanical Properties of a New Polymeric Microcapsule for Self-Healing Cementitious Materials

    PubMed Central

    Lv, Leyang; Schlangen, Erik; Yang, Zhengxian; Xing, Feng

    2016-01-01

    Self-healing cementitious materials containing a microencapsulated healing agent are appealing due to their great application potential in improving the serviceability and durability of concrete structures. In this study, poly(phenol–formaldehyde) (PF) microcapsules that aim to provide a self-healing function for cementitious materials were prepared by an in situ polymerization reaction. Size gradation of the synthesized microcapsules was achieved through a series of sieving processes. The shell thickness and the diameter of single microcapsules was accurately measured under environmental scanning electron microscopy (ESEM). The relationship between the physical properties of the synthesized microcapsules and their micromechanical properties were investigated using nanoindentation. The results of the mechanical tests show that, with the increase of the mean size of microcapsules and the decrease of shell thickness, the mechanical force required to trigger the self-healing function of microcapsules increased correspondingly from 68.5 ± 41.6 mN to 198.5 ± 31.6 mN, featuring a multi-sensitive trigger function. Finally, the rupture behavior and crack surface of cement paste with embedded microcapsules were observed and analyzed using X-ray computed tomography (XCT). The synthesized PF microcapsules may find potential application in self-healing cementitious materials. PMID:28774144

  2. Hydrogen peroxide filled poly(methyl methacrylate) microcapsules: potential oxygen delivery materials.

    PubMed

    Mallepally, Rajendar R; Parrish, Chance C; Mc Hugh, Mark A M; Ward, Kevin R

    2014-11-20

    This paper describes the synthesis of H₂O₂-H₂O filled poly(methyl methacrylate) (PMMA) microcapsules as potential candidates for controlled O₂ delivery. The microcapsules are prepared by a water-in-oil solvent emulsion and evaporation method. The results of this study describe the effect of process parameters on the characteristics of the microcapsules and on their in vitro performance. The size of the microcapsules, as determined from scanning electron microscopy, ranges from ∼5 to 30 μm and the size distribution is narrow. The microcapsules exhibit an internal morphology with entrapped H₂O₂-H₂O droplets randomly distributed in the PMMA continuous phase. In vitro release studies of 4.5 wt% H₂O₂-loaded microcapsules show that ∼70% of the H₂O₂ releases in 24h. This corresponds to a total O₂ production of ∼12 cc/gram of dry microcapsules. Shelf-life studies show that the microcapsules retain ∼84 wt% of the initially loaded H₂O₂ after nine months storage at 2-8 °C, which is an attractive feature for clinical applications.

  3. Preparation and characterisation of biodegradable pollen-chitosan microcapsules and its application in heavy metal removal.

    PubMed

    Sargın, İdris; Kaya, Murat; Arslan, Gulsin; Baran, Talat; Ceter, Talip

    2015-02-01

    Biosorbents have been widely used in heavy metal removal. New resources should be exploited to develop more efficient biosorbents. This study reports the preparation of three novel chitosan microcapsules from pollens of three common, wind-pollinated plants (Acer negundo, Cupressus sempervirens and Populus nigra). The microcapsules were characterized (Fourier transform infrared spectroscopy, thermogravimetric analysis, scanning electron microscopy and elemental analysis) and used in removal of heavy metal ions: Cd(II), Cr(III), Cu(II), Ni(II) and Zn(II). Their sorption capacities were compared to those of cross-linked chitosan beads without pollen grains. C. sempervirens-chitosan microcapsules exhibited better performance (Cd(II): 65.98; Cu(II): 67.10 and Zn(II): 49.55 mg g(-1)) than the other microcapsules and the cross-linked beads. A. negundo-chitosan microcapsules were more efficient in Cr(III) (70.40 mg g(-1)) removal. P. nigra-chitosan microcapsules were found to be less efficient. Chitosan-pollen microcapsules (except P. nigra-chitosan microcapsules) can be used in heavy metal removal.

  4. Micromechanical Properties of a New Polymeric Microcapsule for Self-Healing Cementitious Materials.

    PubMed

    Lv, Leyang; Schlangen, Erik; Yang, Zhengxian; Xing, Feng

    2016-12-20

    Self-healing cementitious materials containing a microencapsulated healing agent are appealing due to their great application potential in improving the serviceability and durability of concrete structures. In this study, poly(phenol-formaldehyde) (PF) microcapsules that aim to provide a self-healing function for cementitious materials were prepared by an in situ polymerization reaction. Size gradation of the synthesized microcapsules was achieved through a series of sieving processes. The shell thickness and the diameter of single microcapsules was accurately measured under environmental scanning electron microscopy (ESEM). The relationship between the physical properties of the synthesized microcapsules and their micromechanical properties were investigated using nanoindentation. The results of the mechanical tests show that, with the increase of the mean size of microcapsules and the decrease of shell thickness, the mechanical force required to trigger the self-healing function of microcapsules increased correspondingly from 68.5 ± 41.6 mN to 198.5 ± 31.6 mN, featuring a multi-sensitive trigger function. Finally, the rupture behavior and crack surface of cement paste with embedded microcapsules were observed and analyzed using X-ray computed tomography (XCT). The synthesized PF microcapsules may find potential application in self-healing cementitious materials.

  5. Photovoltaic encapsulation materials

    NASA Technical Reports Server (NTRS)

    Baum, B.; Willis, P. W.; Cuddihy, E. C.

    1981-01-01

    Candidate materials for the construction of cost-effective solar cell flat array modules are reviewed. Fabrication goals include electricity production at $.70/W with a lifetime of 20 yr. Research is currently directed toward low cost encapsulants and substrates for the cells, and outer covers which resist weathering. Ethylene/vinyl acetate copolymer (EVA) at $.09/sq ft has displayed the most promising results as the encapsulant laminate when subjected to peroxide cross-linking to prevent melting. EVA accepts the addition of antioxidants, quenchers, absorbers, and stabilizers. Wood is favored as the rigid substrate due to cost, while top covers in substrate modules comprise candidate acrylic and polyvinyl fluoride films and a copolymer. Finally, fiberglass mat is placed between the substrate and the EVA pottant as a mechanical support and for electrical insulation.

  6. Production of RS4 from rice starch and its utilization as an encapsulating agent for targeted delivery of probiotics.

    PubMed

    Ashwar, Bilal Ahmad; Gani, Asir; Gani, Adil; Shah, Asima; Masoodi, Farooq Ahmad

    2018-01-15

    The research reported in this article is based on the hypothesis that crosslinking of starch can make it a potential wall material for targeted delivery of probiotics by altering its digestion. Three probiotic strains namely Lactobacillus casei, Lactobacillus brevis and Lactobacillus plantarum were microencapsulated with resistant starch. Encapsulation yield (%) of resistant starch microspheres was in the range of 43.01-48.46. The average diameter of resistant starch microparticles was in the range of 45.53-49.29μm. Fourier transform infrared (FT-IR) spectroscopy of microcapsules showed peaks in the region of 900-1300cm(-1) and 2918-2925cm(-1) which corresponds to the presence of bacteria. Differential Scanning Calorimeter (DSC) showed better thermal stability of resistant starch microcapsules. Microencapsulated probiotics survived well in simulated gastrointestinal conditions and adverse heat conditions. The viability of the microcapsulated lactobacilli also remained high (>7 log cfu g(-1)) for 2months at 4°C. The results revealed that resistant starch is the potential new delivery carrier for oral administration of probiotics. Copyright © 2017 Elsevier Ltd. All rights reserved.

  7. GOES-R Encapsulation

    NASA Image and Video Library

    2016-10-21

    Team members with United Launch Alliance (ULA) prepare the Geostationary Operational Environmental Satellite (GOES-R) for encapsulation in the payload fairing inside the Astrotech payload processing facility in Titusville, Florida near NASA’s Kennedy Space Center. GOES-R will be the first satellite in a series of next-generation NOAA GOES Satellites. The spacecraft is to launch aboard a ULA Atlas V rocket in November.

  8. Magnetic/gold nanoparticle functionalized biocompatible microcapsules with sensitivity to laser irradiation.

    PubMed

    Gorin, Dmitry A; Portnov, Sergey A; Inozemtseva, Olga A; Luklinska, Zofia; Yashchenok, Alexey M; Pavlov, Anton M; Skirtach, Andre G; Möhwald, Helmuth; Sukhorukov, Gleb B

    2008-12-07

    Nanocomposite microcapsules with both gold and magnetite nanoparticles in the shell were prepared in a layer-by-layer procedure using biocompatible polyelectrolytes and nanoparticles. The process of a nanocomposite multilayer formation was investigated using a quartz crystal microbalance (QCM). In addition, nanocomposite microcapsules were characterized by atomic force microscopy (AFM), transmission electron microscopy (TEM) and energy-dispersive X-ray spectroscopy (EDX). It is found that the amount of adsorbed nanoparticles is similar for nanoparticles of various sizes, while the concentration of gold nanoparticles in the shell is higher for smaller nanoparticles. Adsorption of gold nanoparticles is found to be more effective than adsorption of magnetic nanoparticles. Multifunctionality of microcapsules is manifested by dual: magnetic and optical responses. Iron oxide nanoparticles embedded in the microcapsule shell allowed for control over capsules positioning by external magnetic fields. Furthermore, the nanocomposite microcapsules could be opened by laser irradiation; these results are of interest for medical and biological applications.

  9. Phoxim Microcapsules Prepared with Polyurea and Urea-Formaldehyde Resins Differ in Photostability and Insecticidal Activity.

    PubMed

    Zhang, Da-xia; Li, Bei-xing; Zhang, Xian-peng; Zhang, Zheng-qun; Wang, Wei-chang; Liu, Feng

    2016-04-13

    The application of pesticide microcapsules (MCs) in agriculture is becoming more and more popular. In this study, the effects of different wall materials on the stomach toxicity, contact toxicity, length of efficacy, and photolysis characteristics of pesticide microcapsules were investigated. The results showed that microencapsulation reduced the stomach and contact toxicities of phoxim and prolonged the efficacy of this light-sensitive chemical in the greenhouse test. Neither of the degradation curves for microencapsulated phoxim under ultraviolet light fit a first-order model, although the emulsifiable concentrate (EC) degradation curve fit it well. The phoxim-loaded polyurea microcapsules (PUA-MCs) showed significantly increased UV-resistance ability, stomach toxicity, and contact toxicity compared with the phoxim-loaded urea-formaldehyde microcapsules (UF-MCs). These experiments indicated that it is crucial to select the appropriate wall materials for pesticide microcapsules on the basis of application sites and physicochemical properties of pesticide active ingredients.

  10. Assembly of MOF Microcapsules with Size-Selective Permeability on Cell Walls.

    PubMed

    Li, Wanbin; Zhang, Yufan; Xu, Zehai; Meng, Qin; Fan, Zheng; Ye, Shuaiju; Zhang, Guoliang

    2016-01-18

    The assembly of metal-organic frameworks (MOFs) into microcapsules has attracted great interest because of their unique properties. However, it remains a challenge to obtain MOF microcapsules with size selectivity at the molecular scale. In this report, we used cell walls from natural biomaterials as non-toxic, stable, and inexpensive support materials to assemble MOF/cell wall (CW) microcapsules with size-selective permeability. By making use of the hollow structure, small pores, and high density of heterogeneous nucleation sites of the cell walls, uniform and continuous MOF layers could be easily obtained by inside/outside interfacial crystallization. The prepared MOF/CW microcapsules have excellent stability and enable the steady, slow, and size-selective release of small molecules. Moreover, the size selectivity of the microcapsules can be adjusted by changing the type of deposited MOF. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Multifunctional polyelectrolyte microcapsules as a contrast agent for photoacoustic imaging in blood.

    PubMed

    Yashchenok, Alexey M; Jose, Jithin; Trochet, Philippe; Sukhorukov, Gleb B; Gorin, Dmitry A

    2016-08-01

    The polyelectrolyte microcapsules that can be accurate either visualized in biological media or in tissue would enhance their further in vivo application both as a carrier of active payloads and as a specific sensor. The immobilization of active species, for instance fluorescent dyes, quantum dots, metal nanoparticles, in polymeric shell enables visualization of capsules by optical imaging techniques in aqueous solution. However, for visualization of capsules in complex media an instrument with high contrast modality requires. Herein, we show for the first time photoacoustic imaging (PAI) of multifunctional microcapsules in water and in blood. The microcapsules exhibit greater photoacoustic intensity compare to microparticles with the same composition of polymeric shell presumably their higher thermal expansion. Photoacoustic intensity form microcapsules dispersed in blood displays an enhancement (2-fold) of signal compare to blood. Photoacoustic imaging of microcapsules might contribute to non-invasive carrier visualization and further their in vivo distribution.

  12. Outer eggshell membrane as delivery vehicle for polysaccharide/protein microcapsules incorporated with vitamin E.

    PubMed

    Chai, Zhi; Li, Yuanyuan; Liu, Fei; Du, Bingjian; Jiao, Tong; Zhang, Chunyue; Leng, Xiaojing

    2013-01-23

    This study investigates the features of a new type of delivery system prepared by combining a natural outer eggshell membrane (OESM) with emulsified microcapsules. The loading efficiency, controlled release properties, and forming mechanisms of the prepared system were studied. The polysaccharide/protein microcapsules incorporated with vitamin E can be attached to highly cross-linked protein fiber networks of OESM. This attachment could be reinforced more than 2-fold using glutaraldehyde as a cross-linking agent. The combined OESM/microcapsule delivery system significantly exhibited better controlled release properties than the microcapsules alone because of the steric blocking effect. Moreover, the OESM delivery system incorporated with microcapsules formed by pectin/protein as wall material showed more resistance against enzymatic attacks because of the formation of compact aggregates promoted by electrostatic effects.

  13. Polarization Reconfigurable Patch Antenna Using Microelectromechanical Systems (MEMS) Actuators

    NASA Technical Reports Server (NTRS)

    Simons, Rainee N.; Chun, Donghoon; Katehi, Linda P. B.

    2002-01-01

    The paper demonstrates a nearly square patch antenna integrated with a novel microelectromechanical systems (MEMS) actuator for reconfiguring the polarization. Experimental results demonstrate that at a fixed frequency, the polarization can be reconfigured, from circular to linear.

  14. Reconfiguration in the Enterprise JavaBean Component Model

    DTIC Science & Technology

    2001-12-01

    Reconfiguration in the Enterprise JavaBean Component Model Matthew J. Rutherford, Kenneth Anderson, Antonio Carzaniga , Dennis Heimbigner, and...Matthew J. Rutherford, Kenneth Anderson, Antonio Carzaniga , Dennis Heimbigner, and Alexander L. Wolf ABSTRACT Reconfiguration is the process of applying

  15. Reconfigurable Fault Tolerance for FPGAs

    NASA Technical Reports Server (NTRS)

    Shuler, Robert, Jr.

    2010-01-01

    The invention allows a field-programmable gate array (FPGA) or similar device to be efficiently reconfigured in whole or in part to provide higher capacity, non-redundant operation. The redundant device consists of functional units such as adders or multipliers, configuration memory for the functional units, a programmable routing method, configuration memory for the routing method, and various other features such as block RAM, I/O (random access memory, input/output) capability, dedicated carry logic, etc. The redundant device has three identical sets of functional units and routing resources and majority voters that correct errors. The configuration memory may or may not be redundant, depending on need. For example, SRAM-based FPGAs will need some type of radiation-tolerant configuration memory, or they will need triple-redundant configuration memory. Flash or anti-fuse devices will generally not need redundant configuration memory. Some means of loading and verifying the configuration memory is also required. These are all components of the pre-existing redundant FPGA. This innovation modifies the voter to accept a MODE input, which specifies whether ordinary voting is to occur, or if redundancy is to be split. Generally, additional routing resources will also be required to pass data between sections of the device created by splitting the redundancy. In redundancy mode, the voters produce an output corresponding to the two inputs that agree, in the usual fashion. In the split mode, the voters select just one input and convey this to the output, ignoring the other inputs. In a dual-redundant system (as opposed to triple-redundant), instead of a voter, there is some means to latch or gate a state update only when both inputs agree. In this case, the invention would require modification of the latch or gate so that it would operate normally in redundant mode, and would separately latch or gate the inputs in non-redundant mode.

  16. Preparation and Characterization of Chitosan-Based Core-Shell Microcapsules Containing Clove Oil.

    PubMed

    Jiang, Ping; Li, Duxin; Xiao, Ya; Yang, Xingxing; Liu, Yuejun

    2015-01-01

    The biodegradable microcapsules based on chitosan for a controlled delivery of clove oil were prepared by the single coagulation process. The effect of chitosan concentration, core to shell ratio, types of emulsifier, flocculating agent and hardening agent on the microcapsule diameter and the particle size distribution of microcapsule were investigated. The optimized conditions for the preparation of microcapsules with well-defined structure and narrow dispersibility were under that (1) the concentration of chitosan was 1.0 wt%, (2) clove oil to chitosan ratio was 75:25, (3) OP-10 and 10 wt% sodium sulfate were used as emulsifier and flocculating agent respectively, and (4) the concentration hardening agent glyoxal was 1 wt% based on the weight of chitosan. The uniform spherical structures with smooth surfaces with a particle size distribution of 1-15 μm were evidenced by SEM images of microcapsules. Core-shell, hetero-structures were confirmed by optical micrograph. The chemical component of the microcapsules was determined by FTIR. Thermal analysis showed the microcapsules were thermally stable below 150 degrees C. It was found that the pH value and temperature play important roles on the release rate of clove oil from the microcapsules. The release volume of clove oil from microcapsules at pH = 7, and pH = 10 were smaller than that at pH = 2. And the release volume of Clove oil from microcapsules at 60 degrees C was smaller than that at 20 degrees C and 40 degrees C, which showed a sustained and prolonged release.

  17. Reconfigurable origami-inspired acoustic waveguides

    PubMed Central

    Babaee, Sahab; Overvelde, Johannes T. B.; Chen, Elizabeth R.; Tournat, Vincent; Bertoldi, Katia

    2016-01-01

    We combine numerical simulations and experiments to design a new class of reconfigurable waveguides based on three-dimensional origami-inspired metamaterials. Our strategy builds on the fact that the rigid plates and hinges forming these structures define networks of tubes that can be easily reconfigured. As such, they provide an ideal platform to actively control and redirect the propagation of sound. We design reconfigurable systems that, depending on the externally applied deformation, can act as networks of waveguides oriented along one, two, or three preferential directions. Moreover, we demonstrate that the capability of the structure to guide and radiate acoustic energy along predefined directions can be easily switched on and off, as the networks of tubes are reversibly formed and disrupted. The proposed designs expand the ability of existing acoustic metamaterials and exploit complex waveguiding to enhance control over propagation and radiation of acoustic energy, opening avenues for the design of a new class of tunable acoustic functional systems. PMID:28138527

  18. Wavelets for full reconfigurable ECG acquisition system

    NASA Astrophysics Data System (ADS)

    Morales, D. P.; García, A.; Castillo, E.; Meyer-Baese, U.; Palma, A. J.

    2011-06-01

    This paper presents the use of wavelet cores for a full reconfigurable electrocardiogram signal (ECG) acquisition system. The system is compound by two reconfigurable devices, a FPGA and a FPAA. The FPAA is in charge of the ECG signal acquisition, since this device is a versatile and reconfigurable analog front-end for biosignals. The FPGA is in charge of FPAA configuration, digital signal processing and information extraction such as heart beat rate and others. Wavelet analysis has become a powerful tool for ECG signal processing since it perfectly fits ECG signal shape. The use of these cores has been integrated in the LabVIEW FPGA module development tool that makes possible to employ VHDL cores within the usual LabVIEW graphical programming environment, thus freeing the designer from tedious and time consuming design of communication interfaces. This enables rapid test and graphical representation of results.

  19. Reconfigurable Embedded System for Electrocardiogram Acquisition.

    PubMed

    Kay, Marcel Seiji; Iaione, Fábio

    2015-01-01

    Smartphones include features that offers the chance to develop mobile systems in medical field, resulting in an area called mobile-health. One of the most common medical examinations is the electrocardiogram (ECG), which allows the diagnosis of various heart diseases, leading to preventative measures and preventing more serious problems. The objective of this study was to develop a wireless reconfigurable embedded system using a FPAA (Field Programmable Analog Array), for the acquisition of ECG signals, and an application showing and storing these signals on Android smartphones. The application also performs the partial FPAA reconfiguration in real time (adjustable gain). Previous studies using FPAA usually use the development boards provided by the manufacturer (high cost), do not allow the reconfiguration in real time, use no smartphone and communicate via cables. The parameters tested in the acquisition circuit and the quality of ECGs registered in an individual were satisfactory.

  20. All optical reconfiguration of optomechanical filters.

    PubMed

    Deotare, Parag B; Bulu, Irfan; Frank, Ian W; Quan, Qimin; Zhang, Yinan; Ilic, Rob; Loncar, Marko

    2012-05-22

    Reconfigurable optical filters are of great importance for applications in optical communication and information processing. Of particular interest are tuning techniques that take advantage of mechanical deformation of the devices, as they offer wider tuning range. Here we demonstrate reconfiguration of coupled photonic crystal nanobeam cavities by using optical gradient force induced mechanical actuation. Propagating waveguide modes that exist over a wide wavelength range are used to actuate the structures and control the resonance of localized cavity modes. Using this all-optical approach, more than 18 linewidths of tuning range is demonstrated. Using an on-chip temperature self-referencing method, we determine that 20% of the total tuning was due to optomechanical reconfiguration and the rest due to thermo-optic effects. By operating the device at frequencies higher than the thermal cutoff, we show high-speed operation dominated by just optomechanical effects. Independent control of mechanical and optical resonances of our structures is also demonstrated.

  1. Reconfigurable origami-inspired acoustic waveguides.

    PubMed

    Babaee, Sahab; Overvelde, Johannes T B; Chen, Elizabeth R; Tournat, Vincent; Bertoldi, Katia

    2016-11-01

    We combine numerical simulations and experiments to design a new class of reconfigurable waveguides based on three-dimensional origami-inspired metamaterials. Our strategy builds on the fact that the rigid plates and hinges forming these structures define networks of tubes that can be easily reconfigured. As such, they provide an ideal platform to actively control and redirect the propagation of sound. We design reconfigurable systems that, depending on the externally applied deformation, can act as networks of waveguides oriented along one, two, or three preferential directions. Moreover, we demonstrate that the capability of the structure to guide and radiate acoustic energy along predefined directions can be easily switched on and off, as the networks of tubes are reversibly formed and disrupted. The proposed designs expand the ability of existing acoustic metamaterials and exploit complex waveguiding to enhance control over propagation and radiation of acoustic energy, opening avenues for the design of a new class of tunable acoustic functional systems.

  2. A dynamically reconfigurable data stream processing system

    SciTech Connect

    Nogiec, J.M.; Trombly-Freytag, K.; /Fermilab

    2004-11-01

    This paper describes a component-based framework for data stream processing that allows for configuration, tailoring, and runtime system reconfiguration. The system's architecture is based on a pipes and filters pattern, where data is passed through routes between components. A network of pipes and filters can be dynamically reconfigured in response to a preplanned sequence of processing steps, operator intervention, or a change in one or more data streams. This framework provides several mechanisms supporting dynamic reconfiguration and can be used to build static data stream processing applications such as monitoring or data acquisition systems, as well as self-adjusting systems that can adapt their processing algorithm, presentation layer, or data persistency layer in response to changes in input data streams.

  3. Enhanced enrichment of prostate cancer stem-like cells with miniaturized 3D culture in liquid core-hydrogel shell microcapsules

    PubMed Central

    Yu, Jianhua; Lu, Xiongbin; Zynger, Debra L.; He, Xiaoming

    2015-01-01

    Cancer stem-like cells (CSCs) are rare subpopulations of cancer cells that are reported to be responsible for cancer resistance and metastasis associated with conventional cancer therapies. Therefore, effective enrichment/culture of CSCs is of importance to both the understanding and treatment of cancer. However, it usually takes approximately 10 days for the widely used conventional approach to enrich CSCs through the formation of CSC-containing aggregates. Here we report the time can be shortened to 2 days while obtaining prostate CSC-containing aggregates with better quality based on the expression of surface receptor markers, dye exclusion, gene and protein expression, and in vivo tumorigenicity. This is achieved by encapsulating and culturing human prostate cancer cells in the miniaturized 3D liquid core of microcapsules with an alginate hydrogel shell. The miniaturized 3D culture in core–shell microcapsules is an effective strategy for enriching/culturing CSCs in vitro to facilitate cancer research and therapy development. PMID:24952981

  4. Reducing Redundancies in Reconfigurable Antenna Structures Using Graph Models

    SciTech Connect

    Costantine, Joseph; al-Saffar, Sinan; Christodoulou, Christos G.; Abdallah, Chaouki T.

    2010-04-23

    Many reconfigurable antennas have redundant components in their structures. In this paper we present an approach for reducing redundancies in reconfigurable antenna structures using graph models. We study reconfigurable antennas, which are grouped, categorized and modeled according to a set of proposed graph rules. Several examples are presented and discussed to demonstrate the validity of this new technique.

  5. Preparation of a novel chitosan-microcapsules/starch blend film and the study of its drug-release mechanism.

    PubMed

    Huo, Weiqiang; Xie, Gancheng; Zhang, Weixin; Wang, Wei; Shan, Junyang; Liu, Hechou; Zhou, Xiaohua

    2016-06-01

    A novel drug delivery system, chitosan-microcapsules/starch blend film for antofloxacin controlled release, was prepared, and characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (X-RD), thermogravimetry and derivative thermogravimetry (TG/DTG), and scanning electron microscopy (SEM). Following incorporation of the chitosan-microcapsules in the film matrix, the synergistic interactions between these drug-carriers were significant. The thermostability and mechanical properties of the blend film were greatly improved by the incorporation of the microcapsules. The water resistance of the blend film was enhanced by increasing the content of microcapsules, indicating that the microcapsules acted as moisture barriers. After being incorporated, chitosan-microcapsules/starch blend film shows a sustained drug release. The extent of the film degradation and microcapsules swelling in the release system indicated that the drug released of the blend film was pH-sensitive. The blend film exhibited pharmacodynamic efficacy because of the efficient drug releasing.

  6. A Reconfigurable Communications System for Small Spacecraft

    NASA Technical Reports Server (NTRS)

    Chu, Pong P.; Kifle, Muli

    2004-01-01

    Two trends of NASA missions are the use of multiple small spacecraft and the development of an integrated space network. To achieve these goals, a robust and agile communications system is needed. Advancements in field programmable gate array (FPGA) technology have made it possible to incorporate major communication and network functionalities in FPGA chips; thus this technology has great potential as the basis for a reconfigurable communications system. This report discusses the requirements of future space communications, reviews relevant issues, and proposes a methodology to design and construct a reconfigurable communications system for small scientific spacecraft.

  7. Evolvable circuit with transistor-level reconfigurability

    NASA Technical Reports Server (NTRS)

    Stoica, Adrian (Inventor); Salazar-Lazaro, Carlos Harold (Inventor)

    2004-01-01

    An evolvable circuit includes a plurality of reconfigurable switches, a plurality of transistors within a region of the circuit, the plurality of transistors having terminals, the plurality of transistors being coupled between a power source terminal and a power sink terminal so as to be capable of admitting power between the power source terminal and the power sink terminal, the plurality of transistors being coupled so that every transistor terminal to transistor terminal coupling within the region of the circuit comprises a reconfigurable switch.

  8. Reconfigurable manufacturing execution system for pipe cutting

    NASA Astrophysics Data System (ADS)

    Yin, Y. H.; Xie, J. Y.

    2011-08-01

    This article presents a reconfigurable manufacturing execution system (RMES) filling the gap between enterprise resource planning and resource layer for pipe-cutting production with mass customisation and rapid adaptation to dynamic market, which consists of planning and scheduling layer and executive control layer. Starting from customer's task and process requirements, the cutting trajectories are planned under generalised mathematical model able to reconfigure in accordance with various intersecting types' joint, and all tasks are scheduled by nesting algorithm to maximise the utilisation rate of rough material. This RMES for pipe cutting has been effectively implemented in more than 100 companies.

  9. Hybrid antenna synthesis for reconfigurable contoured beams

    NASA Astrophysics Data System (ADS)

    Searle, A. D.; Westcott, B. S.

    1993-08-01

    A reflector illuminated by a small phased array is an attractive antenna configuration for systems requiring reconfigurable contoured beams. The use of a shaped reflector can provide control of the feed power distribution and antenna geometry. A systematic reflector synthesis technique based on geometric optics is formulated, using complex coordinate notation and illustrated by application to a simple design requirement. Results demonstrate that geometric shaping can be successfully applied to systems with distributed sources, and that significant beam reconfiguration can be achieved by phase-only control of the feed array.

  10. Reconfigurable Robust Routing for Mobile Outreach Network

    NASA Technical Reports Server (NTRS)

    Lin, Ching-Fang

    2010-01-01

    The Reconfigurable Robust Routing for Mobile Outreach Network (R3MOO N) provides advanced communications networking technologies suitable for the lunar surface environment and applications. The R3MOON techn ology is based on a detailed concept of operations tailored for luna r surface networks, and includes intelligent routing algorithms and wireless mesh network implementation on AGNC's Coremicro Robots. The product's features include an integrated communication solution inco rporating energy efficiency and disruption-tolerance in a mobile ad h oc network, and a real-time control module to provide researchers an d engineers a convenient tool for reconfiguration, investigation, an d management.

  11. Module Encapsulant Diagnostic and Modeling

    SciTech Connect

    Kempe, M.

    2005-01-01

    Encapsulant materials are used in photovoltaic devices for mechanical support, electrical isolation, and protection against corrosion. The ability of an encapsulant to protect against surface corrosion is related to its adhesional strength. The adhesion of candidate encapsulants under accelerated environmental stress was examined to determine what materials have the best hydrolytic stability and are more likely to reduce corrosion rates. Under environmental exposure, the ingress of water has been correlated with increased corrosion rates. The diffusivity of different encapsulants has been measured to determine how long it takes for water to enter a module. The high diffusivity of ethylene vinyl acetate indicates that, even with the use of an impermeable back-sheet, moisture from the sides will diffuse throughout the entire module. To significantly reduce moisture ingress requires a true hermetic seal, the use of an encapsulant loaded with desiccant, or the use of a very low diffusivity encapsulant.

  12. Selective encapsulation by Janus particles

    SciTech Connect

    Li, Wei; Ruth, Donovan; Gunton, James D.; Rickman, Jeffrey M.

    2015-06-28

    We employ Monte Carlo simulation to examine encapsulation in a system comprising Janus oblate spheroids and isotropic spheres. More specifically, the impact of variations in temperature, particle size, inter-particle interaction range, and strength is examined for a system in which the spheroids act as the encapsulating agents and the spheres as the encapsulated guests. In this picture, particle interactions are described by a quasi-square-well patch model. This study highlights the environmental adaptation and selectivity of the encapsulation system to changes in temperature and guest particle size, respectively. Moreover, we identify an important range in parameter space where encapsulation is favored, as summarized by an encapsulation map. Finally, we discuss the generalization of our results to systems having a wide range of particle geometries.

  13. Smart Actuators and Adhesives for Reconfigurable Matter.

    PubMed

    Ko, Hyunhyub; Javey, Ali

    2017-03-06

    Biological systems found in nature provide excellent stimuli-responsive functions. The camouflage adaptation of cephalopods (octopus, cuttlefish), rapid stiffness change of sea cucumbers, opening of pine cones in response to humidity, and rapid closure of Venus flytraps upon insect touch are some examples of nature's smart systems. Although current technologies are still premature to mimic these sophisticated structures and functions in smart biological systems, recent work on stimuli-responsive programmable matter has shown great progress. Stimuli-responsive materials based on hydrogels, responsive nanocomposites, hybrid structures, shape memory polymers, and liquid crystal elastomers have demonstrated excellent responsivities to various stimuli such as temperature, light, pH, and electric field. However, the technologies in these stimuli-responsive materials are still not sophisticated enough to demonstrate the ultimate attributes of an ideal programmable matter: fast and reversible reconfiguration of programmable matter into complex and robust shapes. Recently, reconfigurable (or programmable) matter that reversibly changes its structure/shape or physical/chemical properties in response to external stimuli has attracted great interest for applications in sensors, actuators, robotics, and smart systems. In particular, key attributes of programmable matter including fast and reversible reconfiguration into complex and robust 2D and 3D shapes have been demonstrated by various approaches. In this Account, we review focused areas of smart materials with special emphasis on the material and device structure designs to enhance the response time, reversibility, multistimuli responsiveness, and smart adhesion for efficient shape transformation and functional actuations. First, the capability of fast reconfiguration of 2D and 3D structures in a reversible way is a critical requirement for programmable matter. For the fast and reversible reconfiguration, various approaches

  14. Encapsulation of graphene in Parylene

    NASA Astrophysics Data System (ADS)

    Skoblin, Grigory; Sun, Jie; Yurgens, August

    2017-01-01

    Graphene encapsulated between flakes of hexagonal boron nitride (hBN) demonstrates the highest known mobility of charge carriers. However, the technology is not scalable to allow for arrays of devices. We are testing a potentially scalable technology for encapsulating graphene where we replace hBN with Parylene while still being able to make low-ohmic edge contacts. The resulting encapsulated devices show low parasitic doping and a robust Quantum Hall effect in relatively low magnetic fields <5 T.

  15. Surface-functionalized diatom microcapsules for drug delivery of water-insoluble drugs.

    PubMed

    Aw, Moom Sinn; Bariana, Manpreet; Yu, Yang; Addai-Mensah, Jonas; Losic, Dusan

    2013-08-01

    Naturally available and biocompatible materials are potential substitutes for synthetic mesoporous materials as suitable drug carriers for the development of cost-effective drug delivery systems. This work investigates the application of a porous silica material derived from diatoms, also known as diatomaceous earth. The aim is to explore the surface functionalization of diatom microcapsules and their impact on the drug loading and release characteristics of water-insoluble drugs. Indomethacin was used as the model for poorly soluble drug. The surface modification on diatoms was performed with two organosilanes; 3-aminopropyltriethoxy silane and N-(3-(trimethoxysilyl) propyl) ethylene diamine and phosphonic acids (2-carboxyethyl-phosphonic acid and 16-phosphono-hexadecanoic acid) providing organic surface hydrophilic and hydrophobic properties. Extensive characterizations using scanning electron microscopy, X-ray photoelectron spectroscopy and differential scanning calorimetry was performed to confirm covalent grafting of monolayer aminosilane and phosphonic acid on the diatom surfaces. Differences in loading capacity of diatoms (15-24%) and release time (6-15 days) were observed which is due to the presence of different functional groups on the surface. It was found that 2-carboxyethyl-phosphonic acid, 3-aminopropyltriethoxy silane and N-(3-(trimethoxysilyl) propyl) ethylene diamine render diatom surfaces hydrophilic, due to polar carboxyl functional group (COOH) and active amine species (NH and NH2) that favor drug adsorption; better encapsulation efficiency and prolonged release of drugs, over the hydrophobic surface created by 16-phosphono-hexadecanoic acid. This work demonstrates diatom porous silica as a promising drug carrier, with possibility to further improve their performances by tailoring their surface functionalities to achieve the required drug loading and release characteristics for different therapeutic conditions.

  16. Effect of in Vitro Gastrointestinal Digestion on Encapsulated and Nonencapsulated Phenolic Compounds of Carob (Ceratonia siliqua L.) Pulp Extracts and Their Antioxidant Capacity.

    PubMed

    Ydjedd, Siham; Bouriche, Sihem; López-Nicolás, Rubén; Sánchez-Moya, Teresa; Frontela-Saseta, Carmen; Ros-Berruezo, Gaspar; Rezgui, Farouk; Louaileche, Hayette; Kati, Djamel-Edine

    2017-02-01

    To determine the effect of in vitro gastrointestinal digestion on the release and antioxidant capacity of encapsulated and nonencapsulated phenolics carob pulp extracts, unripe and ripe carob pulp extracts were microencapsulated with polycaprolactone via double emulsion/solvent evaporation technique. Microcapsules' characterization was performed using scanning electron microscopy and Fourier transform infrared spectrometry analysis. Total phenolics and flavonoids content and antioxidant activities (ORAC, DPPH, and FRAP) were evaluated after each digestion step. The release of phenolic acids and flavonoids was measured along the digestion process by HPLC-MS/MS analysis. The most important phenolics and flavonoids content as well as antioxidant activities were observed after gastric and intestinal phases for nonencapsulated and encapsulated extracts, respectively. The microencapsulation of carob polyphenols showed a protective effect against pH changes and enzymatic activities along digestion, thereby promoting a controlled release and targeted delivery of the encapsulated compound, which contributed to an increase in its bioaccessibility in the gut.

  17. JPL encapsulation task

    NASA Technical Reports Server (NTRS)

    Willis, P.

    1986-01-01

    A detailed summary of the diverse encapsulation materials and techniques that evolved to meet the cost goals of the Flat-plate Solar Array (FSA) Project is presented. A typical solar cell now consists of low iron glass, two layers of ethylene vinyl acetate (EVA) polymers, a porous space, primers/adhesives, a back cover of Tedlar, and a gasket/seal for a volume cost of $1.30/sq ft. This compares well with the project goal of $1.40/sq ft.

  18. OSIRIS-REx Encapsulation

    NASA Image and Video Library

    2016-08-24

    Inside the Payload Hazardous Servicing Facility at NASA's Kennedy Space Center in Florida, the agency’s Origins, Spectral Interpretation, Resource Identification, Security-Regolith Explorer, or OSIRIS-REx spacecraft is encapsulated in its payload fairing. Targeted for liftoff at 7:05 p.m. EDT Sept. 8, 2016, OSIRIS-Rex will be the first U.S. mission to sample an asteroid, retrieve at least two ounces of surface material and return it to Earth for study. The asteroid, Bennu, may hold clues to the origin of the solar system and the source of water and organic molecules found on Earth.

  19. OSIRIS-REx Encapsulation

    NASA Image and Video Library

    2016-08-24

    Inside the Payload Hazardous Servicing Facility at NASA's Kennedy Space Center in Florida, engineers and technicians encapsulate the agency’s Origins, Spectral Interpretation, Resource Identification, Security-Regolith Explorer, or OSIRIS-REx spacecraft in its payload fairing. Targeted for liftoff at 7:05 p.m. EDT Sept. 8, 2016, OSIRIS-Rex will be the first U.S. mission to sample an asteroid, retrieve at least two ounces of surface material and return it to Earth for study. The asteroid, Bennu, may hold clues to the origin of the solar system and the source of water and organic molecules found on Earth.

  20. Foam encapsulated targets

    DOEpatents

    Nuckolls, John H.; Thiessen, Albert R.; Dahlbacka, Glen H.

    1983-01-01

    Foam encapsulated laser-fusion targets wherein a quantity of thermonuclear fuel is embedded in low density, microcellular foam which serves as an electron conduction channel for symmetrical implosion of the fuel by illumination of the target by one or more laser beams. The fuel, such as DT, is contained within a hollow shell constructed of glass, for example, with the foam having a cell size of preferably no greater than 2 .mu.m, a density of 0.065 to 0.6.times.10.sup.3 kg/m.sup.3, and external diameter of less than 200 .mu.m.