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Sample records for individual airborne microparticles

  1. Real-Time Analysis of Individual Airborne Microparticles Using Laser Ablation Mass Spectroscopy and Genetically Trained Neural Networks

    SciTech Connect

    Parker, E.P.; Rosenthal, S.E.; Trahan, M.W.; Wagner, J.S.

    1999-01-22

    We are developing a method for analysis of airborne microparticles based on laser ablation of individual molecules in an ion trap mass spectrometer. Airborne particles enter the spectrometer through a differentially-pumped inlet, are detected by light scattered from two CW laser beams, and sampled by a pulsed excimer laser as they pass through the center of the ion trap electrodes. After the laser pulse, the stored ions are separated by conventional ion trap methods. The mass spectra are then analyzed using genetically-trained neural networks (NNs). A number of mass spectra are averaged to obtain training cases which contain a recognizable spectral signature. Averaged spectra for a bacteria and a non-bacteria are shown to the NNs, the response evaluated, and the weights of the connections between neurodes adjusted by a Genetic Algorithm (GA) such that the output from the NN ranges from 0 for non-bacteria to 1 for bacteria. This process is iterated until the population of the GA converges or satisfies predetermined stopping criteria. Using this type of bipolar training we have obtained generalizing NNs able to distinguish five new bacteria from five new non-bacteria, none of which were used in training the NN.

  2. Detection and Identification of Individual Bioaerosol Microparticles

    NASA Astrophysics Data System (ADS)

    Wolf, J. P.; Boutou, V.; Pan, Y. L.; Chang, R. K.

    Real-time detection and identification of biological aerosols, such as bacteria, viruses, or pollens is a key issue for both environmental and strategic purposes. UV-laser in- duced fluorescence (LIF) is a very efficient technique to detect biological tracers (e.g., amino acids) within airborne microparticles and thus identify bioagents in a mixture of aerosols. In order to obtain selectivity, the fluorescence spectrum of each particle has to be recorded individually. We present the LIF spectra of individual biological particles flowing in the air. The observed spectra reveal the signatures of tryptophan, riboflavin, and NADH. High sensitivity and counting rate are obtained using a novel detection design based on a shot-noise limited 32-anodes photomultiplier. While in- creasing the incident laser energy, parasitic non-linear processes can take place. In particular, we show that the fluorescence spectrum of riboflavin containing microparti- cles is modified by a 2-photon photodegradation- excitation process, which might lead to significant identification errors. However, using ultrashort laser pulses significantly reduces these artefacts since the deposited energy is low. Non-linear multiphoton ex- citation (photodegradation free) can even provide attractive features for bioaerosols identification. In particular, we demonstrated theoretically and experimentally that one-, two-, and three-photon excited fluorescence from dye molecules in spherical microdroplets has an asymmetrical angular distribution and is enhanced in the back- ward direction. Femtosecond excitation allowed us to illuminate the microparticles at high intensity without shape deformation and photodegradation. The enhancement ra- tios (of intensities at 180 and 90) reaches 9 for three-photon excitation. Calculations show a plateau above a given size (1-3 micrometers depending on the process order) under which the enhancement drastically decreases. This change in angular depen- dence might be of

  3. Collective and individual glycolytic oscillations in yeast cells encapsulated in alginate microparticles

    NASA Astrophysics Data System (ADS)

    Amemiya, Takashi; Obase, Kouhei; Hiramatsu, Naoki; Itoh, Kiminori; Shibata, Kenichi; Takinoue, Masahiro; Yamamoto, Tetsuya; Yamaguchi, Tomohiko

    2015-06-01

    Yeast cells were encapsulated into alginate microparticles of a few hundred micrometers diameter using a centrifuge-based droplet shooting device. We demonstrate the first experimental results of glycolytic oscillations in individual yeast cells immobilized in this way. We investigated both the individual and collective oscillatory behaviors at different cell densities. As the cell density increased, the amplitude of the individual oscillations increased while their period decreased, and the collective oscillations became more synchronized, with an order parameter close to 1 (indicating high synchrony). We also synthesized biphasic-Janus microparticles encapsulating yeast cells of different densities in each hemisphere. The cellular oscillations between the two hemispheres were entrained at both the individual and population levels. Such systems of cells encapsulated into microparticles are useful for investigating how cell-to-cell communication depends on the density and spatial distribution of cells.

  4. Collective and individual glycolytic oscillations in yeast cells encapsulated in alginate microparticles.

    PubMed

    Amemiya, Takashi; Obase, Kouhei; Hiramatsu, Naoki; Itoh, Kiminori; Shibata, Kenichi; Takinoue, Masahiro; Yamamoto, Tetsuya; Yamaguchi, Tomohiko

    2015-06-01

    Yeast cells were encapsulated into alginate microparticles of a few hundred micrometers diameter using a centrifuge-based droplet shooting device. We demonstrate the first experimental results of glycolytic oscillations in individual yeast cells immobilized in this way. We investigated both the individual and collective oscillatory behaviors at different cell densities. As the cell density increased, the amplitude of the individual oscillations increased while their period decreased, and the collective oscillations became more synchronized, with an order parameter close to 1 (indicating high synchrony). We also synthesized biphasic-Janus microparticles encapsulating yeast cells of different densities in each hemisphere. The cellular oscillations between the two hemispheres were entrained at both the individual and population levels. Such systems of cells encapsulated into microparticles are useful for investigating how cell-to-cell communication depends on the density and spatial distribution of cells. PMID:26117131

  5. Chemical characterization of individual microparticles using an ion trap: real-time chemical analysis of aerosol particles

    SciTech Connect

    Yang, Mo; Whitten, W.B.; Reilly, P.T.A.; Gieray, R.; Ramsey, J.M.

    1996-10-01

    This paper describes initial experiments to perform laser ablation mass spectrometry in real time on airborne microparticles. The microparticles are sampled directly from the air by a particle inlet system into the vacuum chamber of a mass spectrometer. An incoming particle is detected as it passes through two CW laser beams and a pulsed laser is triggered to intercept the particle for laser ablation/ionization in the mass spectrometer. The initial studies were made with an existing ion trap mass spectrometer with the particle sampling occurring at the center of the trap electrodes. Performance of the inlet system, particle detection, and preliminary results are described.

  6. Selective formation of microparticles by homopolyribonucleotides and proteinoids rich in individual amino acis

    NASA Technical Reports Server (NTRS)

    Lacey, J. C., Jr.; Stephens, D. P.; Fox, S. W.

    1979-01-01

    The formation of phase-separated microparticles following the mixing of solutions of homopolyribonucleotides with solutions of several basic thermal proteinoids, each rich in an individual amino acid, has been studied. Three of the 4 proteinoids studied yielded results consistent with a matrix of anticodonicity; the fourth did not. The meaning of these results, and others, relative to a postulated matrix for the genetic coding mechanism is discussed.

  7. Airborne chemicals cause respiratory symptoms in individuals with contact allergy.

    PubMed

    Elberling, J; Linneberg, A; Mosbech, H; Dirksen, A; Menné, T; Nielsen, N H; Madsen, F; Frølund, L; Johansen, J Duus

    2005-02-01

    Exposure to fragrance chemicals causes various eye and airway symptoms. Individuals with perfume contact allergy report these symptoms more frequently than individuals with nickel allergy or no contact allergies. However, the associations between contact allergy and respiratory symptoms elicited by airborne chemicals other than perfumes are unclear. The study aimed to investigate the association between eye and airway symptoms elicited by airborne chemicals (other than perfumes) and contact allergy in a population-based sample. A questionnaire on respiratory symptoms was posted, in 2002, to 1189 individuals who participated in 1997/1998 in a Danish population-based study of allergic diseases. Questions about eye and airway symptoms elicited by different airborne chemicals and airborne proteins were included in the questionnaire. Data from the questionnaire were compared with data on patch testing and prick testing. Having at least 1 positive patch test (adjusted odds ratio 1.7, 95% CI 1.2-2.5) was associated with the symptoms, and the odds ratio increased with the number of positive patch tests (P-value for test for trend <0.05). Bronchial hyperreactivity, female sex and psychological vulnerability were independently associated with symptoms, but no association was found between prick test reactivity to proteins and the symptoms elicited by airborne chemicals.

  8. Lipoprotein-apheresis reduces circulating microparticles in individuals with familial hypercholesterolemia.

    PubMed

    Connolly, Katherine D; Willis, Gareth R; Datta, Dev B N; Ellins, Elizabeth A; Ladell, Kristin; Price, David A; Guschina, Irina A; Rees, D Aled; James, Philip E

    2014-10-01

    Lipoprotein-apheresis (apheresis) removes LDL-cholesterol in patients with severe dyslipidemia. However, reduction is transient, indicating that the long-term cardiovascular benefits of apheresis may not solely be due to LDL removal. Microparticles (MPs) are submicron vesicles released from the plasma membrane of cells. MPs, particularly platelet-derived MPs, are increasingly being linked to the pathogenesis of many diseases. We aimed to characterize the effect of apheresis on MP size, concentration, cellular origin, and fatty acid concentration in individuals with familial hypercholesterolemia (FH). Plasma and MP samples were collected from 12 individuals with FH undergoing routine apheresis. Tunable resistive pulse sensing (np200) and nanoparticle tracking analysis measured a fall in MP concentration (33 and 15%, respectively; P < 0.05) pre- to post-apheresis. Flow cytometry showed MPs were predominantly annexin V positive and of platelet (CD41) origin both pre- (88.9%) and post-apheresis (88.4%). Fatty acid composition of MPs differed from that of plasma, though apheresis affected a similar profile of fatty acids in both compartments, as measured by GC-flame ionization detection. MP concentration was also shown to positively correlate with thrombin generation potential. In conclusion, we show apheresis nonselectively removes annexin V-positive platelet-derived MPs in individuals with FH. These MPs are potent inducers of coagulation and are elevated in CVD; this reduction in pathological MPs could relate to the long-term benefits of apheresis.

  9. Microparticle analysis system and method

    NASA Technical Reports Server (NTRS)

    Morrison, Dennis R. (Inventor)

    2007-01-01

    A device for analyzing microparticles is provided which includes a chamber with an inlet and an outlet for respectively introducing and dispensing a flowing fluid comprising microparticles, a light source for providing light through the chamber and a photometer for measuring the intensity of light transmitted through individual microparticles. The device further includes an imaging system for acquiring images of the fluid. In some cases, the device may be configured to identify and determine a quantity of the microparticles within the fluid. Consequently, a method for identifying and tracking microparticles in motion is contemplated herein. The method involves flowing a fluid comprising microparticles in laminar motion through a chamber, transmitting light through the fluid, measuring the intensities of the light transmitted through the microparticles, imaging the fluid a plurality of times and comparing at least some of the intensities of light between different images of the fluid.

  10. EVALUATION OF AN INDIVIDUALLY PACED COURSE FOR AIRBORNE RADIO CODE OPERATORS. FINAL REPORT.

    ERIC Educational Resources Information Center

    BALDWIN, ROBERT O.; JOHNSON, KIRK A.

    IN THIS STUDY COMPARISONS WERE MADE BETWEEN AN INDIVIDUALLY PACED VERSION OF THE AIRBORNE RADIO CODE OPERATOR (ARCO) COURSE AND TWO VERSIONS OF THE COURSE IN WHICH THE STUDENTS PROGRESSED AT A FIXED PACE. THE ARCO COURSE IS A CLASS C SCHOOL IN WHICH THE STUDENT LEARNS TO SEND AND RECEIVE MILITARY MESSAGES USING THE INTERNATIONAL MORSE CODE. THE…

  11. The Effects of Natural and Anthropogenic Microparticles on Individual Fitness in Daphnia magna.

    PubMed

    Ogonowski, Martin; Schür, Christoph; Jarsén, Åsa; Gorokhova, Elena

    2016-01-01

    Concerns are being raised that microplastic pollution can have detrimental effects on the feeding of aquatic invertebrates, including zooplankton. Both small plastic fragments (microplastics, MPs) produced by degradation of larger plastic waste (secondary MPs; SMPs) and microscopic plastic spheres used in cosmetic products and industry (primary MPs; PMPs) are ubiquitously present in the environment. However, despite the fact that most environmental MPs consist of weathered plastic debris with irregular shape and broad size distribution, experimental studies of organism responses to MP exposure have largely used uniformly sized spherical PMPs. Therefore, effects observed for PMPs in such experiments may not be representative for MP-effects in situ. Moreover, invertebrate filter-feeders are generally well adapted to the presence of refractory material in seston, which questions the potential of MPs at environmentally relevant concentrations to measurably affect digestion in these organisms. Here, we compared responses to MPs (PMPs and SMPs) and naturally occurring particles (kaolin clay) using the cladoceran Daphnia magna as a model organism. We manipulated food levels (0.4 and 9 μg C mL-1) and MP or kaolin contribution to the feeding suspension (<1 to 74%) and evaluated effects of MPs and kaolin on food uptake, growth, reproductive capacity of the daphnids, and maternal effects on offspring survival and feeding. Exposure to SMPs caused elevated mortality, increased inter-brood period and decreased reproduction albeit only at high MP levels in the feeding suspension (74% by particle count). No such effects were observed in either PMP or kaolin treatments. In daphnids exposed to any particle type at the low algal concentration, individual growth decreased by ~15%. By contrast, positive growth response to all particle types was observed at the high algal concentration with 17%, 54% and 40% increase for kaolin, PMP and SMP, respectively. When test particles comprised

  12. The Effects of Natural and Anthropogenic Microparticles on Individual Fitness in Daphnia magna.

    PubMed

    Ogonowski, Martin; Schür, Christoph; Jarsén, Åsa; Gorokhova, Elena

    2016-01-01

    Concerns are being raised that microplastic pollution can have detrimental effects on the feeding of aquatic invertebrates, including zooplankton. Both small plastic fragments (microplastics, MPs) produced by degradation of larger plastic waste (secondary MPs; SMPs) and microscopic plastic spheres used in cosmetic products and industry (primary MPs; PMPs) are ubiquitously present in the environment. However, despite the fact that most environmental MPs consist of weathered plastic debris with irregular shape and broad size distribution, experimental studies of organism responses to MP exposure have largely used uniformly sized spherical PMPs. Therefore, effects observed for PMPs in such experiments may not be representative for MP-effects in situ. Moreover, invertebrate filter-feeders are generally well adapted to the presence of refractory material in seston, which questions the potential of MPs at environmentally relevant concentrations to measurably affect digestion in these organisms. Here, we compared responses to MPs (PMPs and SMPs) and naturally occurring particles (kaolin clay) using the cladoceran Daphnia magna as a model organism. We manipulated food levels (0.4 and 9 μg C mL-1) and MP or kaolin contribution to the feeding suspension (<1 to 74%) and evaluated effects of MPs and kaolin on food uptake, growth, reproductive capacity of the daphnids, and maternal effects on offspring survival and feeding. Exposure to SMPs caused elevated mortality, increased inter-brood period and decreased reproduction albeit only at high MP levels in the feeding suspension (74% by particle count). No such effects were observed in either PMP or kaolin treatments. In daphnids exposed to any particle type at the low algal concentration, individual growth decreased by ~15%. By contrast, positive growth response to all particle types was observed at the high algal concentration with 17%, 54% and 40% increase for kaolin, PMP and SMP, respectively. When test particles comprised

  13. The Effects of Natural and Anthropogenic Microparticles on Individual Fitness in Daphnia magna

    PubMed Central

    Schür, Christoph; Jarsén, Åsa; Gorokhova, Elena

    2016-01-01

    Concerns are being raised that microplastic pollution can have detrimental effects on the feeding of aquatic invertebrates, including zooplankton. Both small plastic fragments (microplastics, MPs) produced by degradation of larger plastic waste (secondary MPs; SMPs) and microscopic plastic spheres used in cosmetic products and industry (primary MPs; PMPs) are ubiquitously present in the environment. However, despite the fact that most environmental MPs consist of weathered plastic debris with irregular shape and broad size distribution, experimental studies of organism responses to MP exposure have largely used uniformly sized spherical PMPs. Therefore, effects observed for PMPs in such experiments may not be representative for MP-effects in situ. Moreover, invertebrate filter-feeders are generally well adapted to the presence of refractory material in seston, which questions the potential of MPs at environmentally relevant concentrations to measurably affect digestion in these organisms. Here, we compared responses to MPs (PMPs and SMPs) and naturally occurring particles (kaolin clay) using the cladoceran Daphnia magna as a model organism. We manipulated food levels (0.4 and 9 μg C mL-1) and MP or kaolin contribution to the feeding suspension (<1 to 74%) and evaluated effects of MPs and kaolin on food uptake, growth, reproductive capacity of the daphnids, and maternal effects on offspring survival and feeding. Exposure to SMPs caused elevated mortality, increased inter-brood period and decreased reproduction albeit only at high MP levels in the feeding suspension (74% by particle count). No such effects were observed in either PMP or kaolin treatments. In daphnids exposed to any particle type at the low algal concentration, individual growth decreased by ~15%. By contrast, positive growth response to all particle types was observed at the high algal concentration with 17%, 54% and 40% increase for kaolin, PMP and SMP, respectively. When test particles comprised

  14. Identification and characterization of individual airborne volcanic ash particles by Raman microspectroscopy.

    PubMed

    Ivleva, Natalia P; Huckele, Susanne; Weinzierl, Bernadett; Niessner, Reinhard; Haisch, Christoph; Baumann, Thomas

    2013-11-01

    We present for the first time the Raman microspectroscopic identification and characterization of individual airborne volcanic ash (VA) particles. The particles were collected in April/May 2010 during research aircraft flights, which were performed by Deutsches Zentrum für Luft- und Raumfahrt in the airspace near the Eyjafjallajökull volcano eruption and over Europe (between Iceland and Southern Germany). In addition, aerosol particles were sampled by an Electrical Low Pressure Impactor in Munich, Germany. As references for the Raman analysis, we used the spectra of VA collected at the ground near the place of eruption, of mineral basaltic rock, and of different minerals from a database. We found significant differences in the spectra of VA and other aerosol particles (e.g., soot, nitrates, sulfates, and clay minerals), which allowed us to identify VA among other atmospheric particulate matter. Furthermore, while the airborne VA shows a characteristic Raman pattern (with broad band from ca. 200 to ca. 700 cm(-1) typical for SiO₂ glasses and additional bands of ferric minerals), the differences between the spectra of aged and fresh particles were observed, suggesting differences in their chemical composition and/or structure. We also analyzed similarities between Eyjafjallajökull VA particles collected at different sampling sites and compared the particles with a large variety of glassy and crystalline minerals. This was done by applying cluster analysis, in order to get information on the composition and structure of volcanic ash. PMID:24121468

  15. Simultaneous determination of the quantity and isotopic ratios of uranium in individual micro-particles by isotope dilution thermal ionization mass spectrometry (ID-TIMS).

    PubMed

    Park, Jong-Ho; Choi, Eun-Ju

    2016-11-01

    A method to determine the quantity and isotopic ratios of uranium in individual micro-particles simultaneously by isotope dilution thermal ionization mass spectrometry (ID-TIMS) has been developed. This method consists of sequential sample and spike loading, ID-TIMS for isotopic measurement, and application of a series of mathematical procedures to remove the contribution of uranium in the spike. The homogeneity of evaporation and ionization of uranium content was confirmed by the consistent ratio of n((233)U)/n((238)U) determined by TIMS measurements. Verification of the method was performed using U030 solution droplets and U030 particles. Good agreements of resulting uranium quantity, n((235)U)/n((238)U), and n((236)U)/n((238)U) with the estimated or certified values showed the validity of this newly developed method for particle analysis when simultaneous determination of the quantity and isotopic ratios of uranium is required.

  16. Simultaneous determination of the quantity and isotopic ratios of uranium in individual micro-particles by isotope dilution thermal ionization mass spectrometry (ID-TIMS).

    PubMed

    Park, Jong-Ho; Choi, Eun-Ju

    2016-11-01

    A method to determine the quantity and isotopic ratios of uranium in individual micro-particles simultaneously by isotope dilution thermal ionization mass spectrometry (ID-TIMS) has been developed. This method consists of sequential sample and spike loading, ID-TIMS for isotopic measurement, and application of a series of mathematical procedures to remove the contribution of uranium in the spike. The homogeneity of evaporation and ionization of uranium content was confirmed by the consistent ratio of n((233)U)/n((238)U) determined by TIMS measurements. Verification of the method was performed using U030 solution droplets and U030 particles. Good agreements of resulting uranium quantity, n((235)U)/n((238)U), and n((236)U)/n((238)U) with the estimated or certified values showed the validity of this newly developed method for particle analysis when simultaneous determination of the quantity and isotopic ratios of uranium is required. PMID:27591656

  17. Microparticles as Potential Biomarkers of Cardiovascular Disease

    PubMed Central

    França, Carolina Nunes; Izar, Maria Cristina de Oliveira; do Amaral, Jônatas Bussador; Tegani, Daniela Melo; Fonseca, Francisco Antonio Helfenstein

    2015-01-01

    Primary prevention of cardiovascular disease is a choice of great relevance because of its impact on health. Some biomarkers, such as microparticles derived from different cell populations, have been considered useful in the assessment of cardiovascular disease. Microparticles are released by the membrane structures of different cell types upon activation or apoptosis, and are present in the plasma of healthy individuals (in levels considered physiological) and in patients with different pathologies. Many studies have suggested an association between microparticles and different pathological conditions, mainly the relationship with the development of cardiovascular diseases. Moreover, the effects of different lipid-lowering therapies have been described in regard to measurement of microparticles. The studies are still controversial regarding the levels of microparticles that can be considered pathological. In addition, the methodologies used still vary, suggesting the need for standardization of the different protocols applied, aiming at using microparticles as biomarkers in clinical practice. PMID:25626759

  18. Assessing visual green effects of individual urban trees using airborne Lidar data.

    PubMed

    Chen, Ziyue; Xu, Bing; Gao, Bingbo

    2015-12-01

    Urban trees benefit people's daily life in terms of air quality, local climate, recreation and aesthetics. Among these functions, a growing number of studies have been conducted to understand the relationship between residents' preference towards local environments and visual green effects of urban greenery. However, except for on-site photography, there are few quantitative methods to calculate green visibility, especially tree green visibility, from viewers' perspectives. To fill this research gap, a case study was conducted in the city of Cambridge, which has a diversity of tree species, sizes and shapes. Firstly, a photograph-based survey was conducted to approximate the actual value of visual green effects of individual urban trees. In addition, small footprint airborne Lidar (Light detection and ranging) data was employed to measure the size and shape of individual trees. Next, correlations between visual tree green effects and tree structural parameters were examined. Through experiments and gradual refinement, a regression model with satisfactory R2 and limited large errors is proposed. Considering the diversity of sample trees and the result of cross-validation, this model has the potential to be applied to other study sites. This research provides urban planners and decision makers with an innovative method to analyse and evaluate landscape patterns in terms of tree greenness.

  19. Sensitivity of the eyes to airborne irritant stimuli: influence of individual characteristics.

    PubMed

    Kjaergaard, S; Pedersen, O F; Mølhave, L

    1992-01-01

    The purpose of this study was to measure trigeminal sensitivity of the eyes to irritative exposures and to examine the influence of individual characteristics, e.g., gender, age, and smoking, on this sensitivity. During an experimental study, 158 of 2,025 randomly selected volunteers were examined for sensory irritation threshold in the eyes to carbon dioxide (CO2). Eyes were exposed to progressive concentrations of CO2 (10, 20, 40, 80, and 160 ml/l), until the subject claimed a distinct irritation. Each exposure level lasted 2 min. A special exposure mask system was used for eyes-only exposure. No significant dependence of gender or smoking was found, but subjects who were less than 40 y of age were more sensitive than were the elderly subjects. Subjects who reported frequent "sick building syndrome" irritation symptoms had lower thresholds (i.e., higher sensitivity). The CO2 threshold was related to skin irritation sensitivity, i.e., response to lactic acid smeared on the cheek, and there were indications that occupational stress was associated with low thresholds. Studies of irritation to n-decane indicate that the CO2 threshold may be an important factor in the prediction of individual sensitivity to irritation from airborne pollutants. The CO2 threshold of the eyes may be of value in the evaluation of hypersensitivity to indoor air pollution. Furthermore, the threshold may be used to assess important relationships between the different trigeminal innervated areas, e.g., skin and eyes. Finally, the method has the advantage of avoiding interference from olfactory stimulation. PMID:1540002

  20. Chemical characterization of individual, airborne sub-10-nm particles and molecules.

    PubMed

    Wang, Shenyi; Zordan, Christopher A; Johnston, Murray V

    2006-03-15

    A nanoaerosol mass spectrometer (NAMS) is described for real-time characterization of individual airborne nanoparticles. The NAMS includes an aerodynamic inlet, quadrupole ion guide, quadrupole ion trap, and time-of-flight mass analyzer. Charged particles in the aerosol are drawn through the aerodynamic inlet, focused through the ion guide, and captured in the ion trap. Trapped particles are irradiated with a high-energy laser pulse to reach the "complete ionization limit" where each particle is thought to be completely disintegrated into atomic ions. In this limit, the relative signal intensities of the atomic ions give the atomic composition. The method is first demonstrated with sucrose particles produced with an electrospray generator. Under the conditions used, the particle detection efficiency (fraction of charged particles entering the inlet that are subsequently analyzed) reaches a maximum of 10(-4) at 9.5 nm in diameter and the size distribution of trapped particles has a geometric standard deviation of 1.1 based on a log-normal distribution. A method to deconvolute overlapping multiply charged ions (e.g. C3+ and O4+) is presented. When applied to sucrose spectra, the measured C/O atomic ratio is 1.1, which matches the expected ratio from the molecular formula. The spectra of singly charged bovine serum albumin (BSA) molecules are also presented, and the measured and expected C/N/O atomic ratios are within 15% of the each other. Also observed in the BSA spectra are signals from 13C and 32S which arise from 40 and approximately 34 atoms per molecule (particle), respectively. Potential applications of NAMS to atmospheric chemistry and biotechnology are briefly discussed. PMID:16536407

  1. Tropical forest structure characterization using airborne lidar data: an individual tree level approach

    NASA Astrophysics Data System (ADS)

    Ferraz, A.; Saatchi, S. S.

    2015-12-01

    Fine scale tropical forest structure characterization has been performed by means of field measurements techniques that record both the specie and the diameter at the breast height (dbh) for every tree within a given area. Due to dense and complex vegetation, additional important ecological variables (e.g. the tree height and crown size) are usually not measured because they are hardly recognized from the ground. The poor knowledge on the 3D tropical forest structure has been a major limitation for the understanding of different ecological issues such as the spatial distribution of carbon stocks, regeneration and competition dynamics and light penetration gradient assessments. Airborne laser scanning (ALS) is an active remote sensing technique that provides georeferenced distance measurements between the aircraft and the surface. It provides an unstructured 3D point cloud that is a high-resolution model of the forest. This study presents the first approach for tropical forest characterization at a fine scale using remote sensing data. The multi-modal lidar point cloud is decomposed into 3D clusters that correspond to single trees by means of a technique called Adaptive Mean Shift Segmentation (AMS3D). The ability of the corresponding individual tree metrics (tree height, crown area and crown volume) for the estimation of above ground biomass (agb) over the 50 ha CTFS plot in Barro Colorado Island is here assessed. We conclude that our approach is able to map the agb spatial distribution with an error of nearly 12% (RMSE=28 Mg ha-1) compared with field-based estimates over 1ha plots.

  2. Flow cytometric analysis of circulating microparticles in plasma.

    PubMed

    Orozco, Aaron F; Lewis, Dorothy E

    2010-06-01

    Microparticles, which include exosomes, micro-vesicles, apoptotic bodies and apoptotic microparticles, are small (0.05 - 3 mum in diameter), membranous vesicles that can contain DNA, RNA, miRNA, intracellular proteins and express extracellular surface markers from the parental cells. They can be secreted from intracellular multivesicular bodies or released from the surface of blebbing membranes. Circulating microparticles are abundant in the plasma of normal individuals and can be derived from circulating blood cells such as platelets, red blood cells and leukocytes as well as from tissue sources, such as endothelial and placental tissues. Elevated levels of microparticles are associated with various diseases such as thrombosis (platelet microparticles), congestive heart failure (endothelial microparticles), breast cancer patients (leukocyte microparticles) and women with preeclampsia (syncytiotrophoblast microparticles). Although microparticles can be detected by microscopy, enzyme-linked immunoassays and functional assays, flow cytometry is the preferred method because of the ability to quantitate (fluorescent bead- or flow rate-based method) and because of polychromatic capabilities. However, standardization of pre-analytical and analytical modus operandi for isolating, enumerating and fluorescent labeling of microparticles remains a challenge. The primary focus of this article is to review the preliminary steps required to optimally study circulating in vivo microparticles which include: 1) centrifugation speed used, 2) quantitation of microparticles before antibody labeling, 3) levels of fluorescence intensity of antibody-labeled microparticles, 4) polychromatic flow cytometric analysis of microparticle sub-populations and 5) use of polyclonal antibodies designed for Western blotting for flow cytometry. These studies determine a roadmap to develop microparticles as biomarkers for a variety of conditions. PMID:20235276

  3. Individual tree crown delineation using localized contour tree method and airborne LiDAR data in coniferous forests

    NASA Astrophysics Data System (ADS)

    Wu, Bin; Yu, Bailang; Wu, Qiusheng; Huang, Yan; Chen, Zuoqi; Wu, Jianping

    2016-10-01

    Individual tree crown delineation is of great importance for forest inventory and management. The increasing availability of high-resolution airborne light detection and ranging (LiDAR) data makes it possible to delineate the crown structure of individual trees and deduce their geometric properties with high accuracy. In this study, we developed an automated segmentation method that is able to fully utilize high-resolution LiDAR data for detecting, extracting, and characterizing individual tree crowns with a multitude of geometric and topological properties. The proposed approach captures topological structure of forest and quantifies topological relationships of tree crowns by using a graph theory-based localized contour tree method, and finally segments individual tree crowns by analogy of recognizing hills from a topographic map. This approach consists of five key technical components: (1) derivation of canopy height model from airborne LiDAR data; (2) generation of contours based on the canopy height model; (3) extraction of hierarchical structures of tree crowns using the localized contour tree method; (4) delineation of individual tree crowns by segmenting hierarchical crown structure; and (5) calculation of geometric and topological properties of individual trees. We applied our new method to the Medicine Bow National Forest in the southwest of Laramie, Wyoming and the HJ Andrews Experimental Forest in the central portion of the Cascade Range of Oregon, U.S. The results reveal that the overall accuracy of individual tree crown delineation for the two study areas achieved 94.21% and 75.07%, respectively. Our method holds great potential for segmenting individual tree crowns under various forest conditions. Furthermore, the geometric and topological attributes derived from our method provide comprehensive and essential information for forest management.

  4. Particulate matter induces prothrombotic microparticle shedding by human mononuclear and endothelial cells.

    PubMed

    Neri, Tommaso; Pergoli, Laura; Petrini, Silvia; Gravendonk, Lotte; Balia, Cristina; Scalise, Valentina; Amoruso, Angela; Pedrinelli, Roberto; Paggiaro, Pierluigi; Bollati, Valentina; Celi, Alessandro

    2016-04-01

    Particulate airborne pollution is associated with increased cardiopulmonary morbidity. Microparticles are extracellular vesicles shed by cells upon activation or apoptosis involved in physiological processes such as coagulation and inflammation, including airway inflammation. We investigated the hypothesis that particulate matter causes the shedding of microparticles by human mononuclear and endothelial cells. Cells, isolated from the blood and the umbilical cords of normal donors, were cultured in the presence of particulate from a standard reference. Microparticles were assessed in the supernatant as phosphatidylserine concentration. Microparticle-associated tissue factor was assessed by an one-stage clotting assay. Nanosight technology was used to evaluate microparticle size distribution. Particulate matter induces a dose- and time- dependent, rapid (1h) increase in microparticle generation in both cells. These microparticles express functional tissue factor. Particulate matter increases intracellular calcium concentration and phospholipase C inhibition reduces microparticle generation. Nanosight analysis confirmed that upon exposure to particulate matter both cells express particles with a size range consistent with the definition of microparticles (50-1000 nm). Exposure of mononuclear and endothelial cells to particulate matter upregulates the generation of microparticles at least partially mediated by calcium mobilization. This observation might provide a further link between airborne pollution and cardiopulmonary morbidity. PMID:26876346

  5. Particulate matter induces prothrombotic microparticle shedding by human mononuclear and endothelial cells.

    PubMed

    Neri, Tommaso; Pergoli, Laura; Petrini, Silvia; Gravendonk, Lotte; Balia, Cristina; Scalise, Valentina; Amoruso, Angela; Pedrinelli, Roberto; Paggiaro, Pierluigi; Bollati, Valentina; Celi, Alessandro

    2016-04-01

    Particulate airborne pollution is associated with increased cardiopulmonary morbidity. Microparticles are extracellular vesicles shed by cells upon activation or apoptosis involved in physiological processes such as coagulation and inflammation, including airway inflammation. We investigated the hypothesis that particulate matter causes the shedding of microparticles by human mononuclear and endothelial cells. Cells, isolated from the blood and the umbilical cords of normal donors, were cultured in the presence of particulate from a standard reference. Microparticles were assessed in the supernatant as phosphatidylserine concentration. Microparticle-associated tissue factor was assessed by an one-stage clotting assay. Nanosight technology was used to evaluate microparticle size distribution. Particulate matter induces a dose- and time- dependent, rapid (1h) increase in microparticle generation in both cells. These microparticles express functional tissue factor. Particulate matter increases intracellular calcium concentration and phospholipase C inhibition reduces microparticle generation. Nanosight analysis confirmed that upon exposure to particulate matter both cells express particles with a size range consistent with the definition of microparticles (50-1000 nm). Exposure of mononuclear and endothelial cells to particulate matter upregulates the generation of microparticles at least partially mediated by calcium mobilization. This observation might provide a further link between airborne pollution and cardiopulmonary morbidity.

  6. Variation in relative quantities of airborne sex pheromone components from individual femaleEphestia cautella (Lepidoptera: Pyralidae).

    PubMed

    Barrer, P M; Lacey, M J; Shani, A

    1987-03-01

    The airborne sex pheromone components (Z,E)-9,12-tetradeca-dien-1-yl acetate and (Z)-9-tetradecen-1-y1 acetate from single calling females ofEphestia cautella (Walker) were trapped within glass capillary tubes and were measured by gas chromatography-mass spectrometry. Broad and similar distributions of relative quantities were found for a laboratory strain and three Australian field strains, and means differed strongly from those reported previously for this species. The overall mean proportion of the two components found for Australian females was 88∶12. The composition in individuals ranged from 63∶27 to 97∶3. The proportions for individuals appeared to vary slightly in a random fashion from day to day, and proportions for first-generation progeny were influenced by the maternal blend.

  7. Microparticles with hierarchical porosity

    SciTech Connect

    Petsev, Dimiter N; Atanassov, Plamen; Pylypenko, Svitlana; Carroll, Nick; Olson, Tim

    2012-12-18

    The present disclosure provides oxide microparticles with engineered hierarchical porosity and methods of manufacturing the same. Also described are structures that are formed by templating, impregnating, and/or precipitating the oxide microparticles and method for forming the same. Suitable applications include catalysts, electrocatalysts, electrocatalysts support materials, capacitors, drug delivery systems, sensors and chromatography.

  8. [Estimating individual tree aboveground biomass of the mid-subtropical forest using airborne LiDAR technology].

    PubMed

    Liu, Feng; Tan, Chang; Lei, Pi-Feng

    2014-11-01

    Taking Wugang forest farm in Xuefeng Mountain as the research object, using the airborne light detection and ranging (LiDAR) data under leaf-on condition and field data of concomitant plots, this paper assessed the ability of using LiDAR technology to estimate aboveground biomass of the mid-subtropical forest. A semi-automated individual tree LiDAR cloud point segmentation was obtained by using condition random fields and optimization methods. Spatial structure, waveform characteristics and topography were calculated as LiDAR metrics from the segmented objects. Then statistical models between aboveground biomass from field data and these LiDAR metrics were built. The individual tree recognition rates were 93%, 86% and 60% for coniferous, broadleaf and mixed forests, respectively. The adjusted coefficients of determination (R(2)adj) and the root mean squared errors (RMSE) for the three types of forest were 0.83, 0.81 and 0.74, and 28.22, 29.79 and 32.31 t · hm(-2), respectively. The estimation capability of model based on canopy geometric volume, tree percentile height, slope and waveform characteristics was much better than that of traditional regression model based on tree height. Therefore, LiDAR metrics from individual tree could facilitate better performance in biomass estimation.

  9. Airborne multispectral identification of individual cotton plants using consumer-grade cameras

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Although multispectral remote sensing using consumer-grade cameras has successfully identified fields of small cotton plants, improvements to detection sensitivity are needed to identify individual or small clusters of plants. The imaging sensor of consumer-grade cameras are based on a Bayer patter...

  10. Microparticle Flow Sensor

    NASA Technical Reports Server (NTRS)

    Morrison, Dennis R.

    2005-01-01

    The microparticle flow sensor (MFS) is a system for identifying and counting microscopic particles entrained in a flowing liquid. The MFS includes a transparent, optoelectronically instrumented laminar-flow chamber (see figure) and a computer for processing instrument-readout data. The MFS could be used to count microparticles (including micro-organisms) in diverse applications -- for example, production of microcapsules, treatment of wastewater, pumping of industrial chemicals, and identification of ownership of liquid products.

  11. Agglomeration of microparticles in complex plasmas

    SciTech Connect

    Du, Cheng-Ran; Thomas, Hubertus M.; Ivlev, Alexei V.; Konopka, Uwe; Morfill, Gregor E.

    2010-11-15

    Agglomeration of highly charged microparticles was observed and studied in complex plasma experiments carried out in a capacitively coupled rf discharge. The agglomeration was caused by strong waves triggered in a particle cloud by decreasing neutral gas pressure. Using a high-speed camera during this unstable regime, it was possible to resolve the motion of individual microparticles and to show that the relative velocities of some particles were sufficiently high to overcome the mutual Coulomb repulsion and hence to result in agglomeration. After stabilizing the cloud again through the increase of the pressure, we were able to observe the aggregates directly with a long-distance microscope. We show that the agglomeration rate deduced from our experiments is in good agreement with theoretical estimates. In addition, we briefly discuss the mechanisms that can provide binding of highly charged microparticles in a plasma.

  12. Retrieval of effective leaf area index (LAIe) and leaf area density (LAD) profile at individual tree level using high density multi-return airborne LiDAR

    NASA Astrophysics Data System (ADS)

    Lin, Yi; West, Geoff

    2016-08-01

    As an important canopy structure indicator, leaf area index (LAI) proved to be of considerable implications for forest ecosystem and ecological studies, and efficient techniques for accurate LAI acquisitions have long been highlighted. Airborne light detection and ranging (LiDAR), often termed as airborne laser scanning (ALS), once was extensively investigated for this task but showed limited performance due to its low sampling density. Now, ALS systems exhibit more competing capacities such as high density and multi-return sampling, and hence, people began to ask the questions like-"can ALS now work better on the task of LAI prediction?" As a re-examination, this study investigated the feasibility of LAI retrievals at the individual tree level based on high density and multi-return ALS, by directly considering the vertical distributions of laser points lying within each tree crown instead of by proposing feature variables such as quantiles involving laser point distribution modes at the plot level. The examination was operated in the case of four tree species (i.e. Picea abies, Pinus sylvestris, Populus tremula and Quercus robur) in a mixed forest, with their LAI-related reference data collected by using static terrestrial laser scanning (TLS). In light of the differences between ALS- and TLS-based LAI characterizations, the methods of voxelization of 3D scattered laser points, effective LAI (LAIe) that does not distinguish branches from canopies and unified cumulative LAI (ucLAI) that is often used to characterize the vertical profiles of crown leaf area densities (LADs) was used; then, the relationships between the ALS- and TLS-derived LAIes were determined, and so did ucLAIs. Tests indicated that the tree-level LAIes for the four tree species can be estimated based on the used airborne LiDAR (R2 = 0.07, 0.26, 0.43 and 0.21, respectively) and their ucLAIs can also be derived. Overall, this study has validated the usage of the contemporary high density multi

  13. Microparticles in tumor progression.

    PubMed

    Falanga, Anna; Tartari, Carmen Julia; Marchetti, Marina

    2012-04-01

    Microparticles (MP) are shed from the surface of activated or apoptotic blood cells and their levels in plasma reflect a balance between cell stimulation, proliferation, and death. MP production occurs through vesiculation of cell membranes, and involves cytoskeletal changes and a shift in the normal phospholipid asymmetry. The expression on the majority of MP of the anionic phosphatidylserine (PS) is responsible for the capacity of MP to support blood coagulation activation. In some cases, PS expression is also associated, in the same MP, with the presence of active Tissue Factor, the main activator of blood coagulation. Elevation in plasma levels of MP have been described in numerous clinical conditions, most of which also associated with an increased thrombotic risk. Particularly, MP have been found to be increased in both solid and hematological malignancies, including myeloproliferative neoplasms. A role of MP in tumor progression has been suggested by both in vitro and in vivo studies. Evidence exists that MP of platelet origin are the main players in this process, being rich in pro-angiogenic factors. The utility of measuring MP as a diagnostic and prognostic marker is currently a subject of intense investigation. The possibility to inhibit MP production by pharmacological interventions represents a future challenge. PMID:22682124

  14. Real-time detection and characterization of individual flowing airborne biological particles: fluorescence spectra and elastic scattering measurements

    NASA Astrophysics Data System (ADS)

    Pan, Yongle; Holler, Stephen; Chang, Richard K.; Hill, Steven C.; Pinnick, Ronald G.; Niles, Stanley; Bottiger, Jerold R.; Bronk, Burt V.

    1999-11-01

    Real-time methods which is reagentless and could detect and partially characterize bioaerosols are of current interest. We present a technique for real-time measurement of UV-excited fluorescence spectra and two-dimensional angular optical scattering (TAOS) from individual flowing biological aerosol particles. The fluorescence spectra have been observed from more than 20 samples including Bacillus subtilis, Escherichia coli, Erwinia herbicola, allergens, dust, and smoke. The S/N and resolution of the spectra are sufficient for observing small lineshape differences among the same type of bioaerosol prepared under different conditions. The additional information from TAOS regarding particle size, shape, and granularity has the potential of aiding in distinguishing bacterial aerosols from other aerosols, such as diesel and cigarette smoke.

  15. Kinetics of solvent extraction/evaporation process for PLGA microparticle fabrication.

    PubMed

    Katou, Hajime; Wandrey, Anne Julia; Gander, Bruno

    2008-11-19

    Organic solvent extraction/evaporation from an o/w-dispersion has been widely used for the fabrication of PLGA microparticles. The purpose of this work was to elucidate the kinetics of the solvent extraction/evaporation process. A mathematical diffusion model was developed and applied to predict the duration of the solvent extraction. As the diffusion coefficient, D(p), plays a major role in the modeled process, a new and experimentally simple method for estimating D(p) was developed. Both the experimental method and the mathematical model were validated through PLGA microparticle fabrication experiments. For microparticles of mode diameters of 2 and 20 microm, the solvent was extracted in approximately 10 s. Sufficient hardening of the microparticles required, however, the evaporation of solvent from the extraction phase. Residual solvent in extraction phase exerted a strong effect on the morphology of the final product as demonstrated by scanning electron microscopy. Only if most solvent was removed from the aqueous extraction phase, a powdery product of individual microparticles was obtained. At residual organic solvent concentration of above 0.2% in the extraction phase, the microparticles strongly aggregated during collection on a membrane filter and final drying. The presented methods may be useful for better controlling microparticle fabrication processes by solvent extraction/evaporation.

  16. Estimating individual-level exposure to airborne polycyclic aromatic hydrocarbons throughout the gestational period based on personal, indoor, and outdoor monitoring

    SciTech Connect

    Choi, H.; Perera, F.; Pac, A.; Wang, L.; Flak, E.; Mroz, E.; Jacek, R.; Chai-Onn, T.; Jedrychowski, W.; Masters, E.; Camann, D.; Spengler, J.

    2008-11-15

    Current understanding on health effects of long-term polycyclic aromatic hydrocarbon (PAH) exposure is limited by lack of data on time-varying nature of the pollutants at an individual level. In a cohort of pregnant women in Krakow, Poland, we examined the contribution of temporal, spatial, and behavioral factors to prenatal exposure to airborne PAHs within each trimester and developed a predictive model of PAH exposure over the entire gestational period. The observed personal, indoor, and outdoor B(a)P levels we observed in Krakow far exceed the recommended Swedish guideline value for B(a)P of 0.1 ng/m{sup 3}. Based on simultaneously monitored levels, the outdoor PAH level alone accounts for 93% of total variability in personal exposure during the heating season. Living near the Krakow bus depot, a crossroad, and the city, center and time spent outdoors or commuting were not associated with higher personal exposure. During the nonheating season only, a 1-hr increase in environmental tobacco smoke (ETS) exposure was associated with a 10-16% increase in personal exposure to the nine measured PAHs. A 1{degree}C decrease in ambient temperature was associated with a 3-5% increase in exposure to benz(a)anthracene, benzo(k)fluoranthene, and dibenz(a,h)anthracene, after accounting for the outdoor concentration. A random effects model demonstrated that mean personal exposure at a given gestational period depends on the season, residence location, and ETS. Considering that most women reported spending < 3 hr/day outdoors, most women in the study were exposed to outdoor-originating PAHs within the indoor setting. Cross-sectional, longitudinal monitoring supplemented with questionnaire data allowed development of a gestation-length model of individual-level exposure with high precision and validity.

  17. Airborne Transparencies.

    ERIC Educational Resources Information Center

    Horne, Lois Thommason

    1984-01-01

    Starting from a science project on flight, art students discussed and investigated various means of moving in space. Then they made acetate illustrations which could be used as transparencies. The projection phenomenon made the illustrations look airborne. (CS)

  18. Method for determining surface properties of microparticles

    DOEpatents

    Eisenthal, Kenneth B.

    2000-01-01

    Second harmonic generation (SHG), sum frequency generation (SFG) and difference frequency generation (DFG) can be used for surface analysis or characterization of microparticles having a non-metallic surface feature. The microparticles can be centrosymmetric or such that non-metallic molecules of interest are centrosymmetrically distributed inside and outside the microparticles but not at the surface of the microparticles where the asymmetry aligns the molecules. The signal is quadratic in incident laser intensity or proportional to the product of two incident laser intensities for SFG, it is sharply peaked at the second harmonic wavelength, quadratic in the density of molecules adsorbed onto the microparticle surface, and linear in microparticles density. In medical or pharmacological applications, molecules of interest may be of drugs or toxins, for example.

  19. Microparticles in physiological and in pathological conditions.

    PubMed

    Roos, Maria Augusta; Gennero, Luisa; Denysenko, Tetyana; Reguzzi, Stefano; Cavallo, Giovanni; Pescarmona, Gian Piero; Ponzetto, Antonio

    2010-10-01

    Chronic diseases pose a severe burden to modern National Health Systems. Individuals nowadays have a far more extended lifespan than in the past, but healthy living was only scantily extended. As much as longer life is desirable, it is saddened by chronic diseases and organ malfunctions. One contributor to these problems was recognized to be represented by microparticles (MPs). Our purpose is to better understand MPs, to contrast their ominous threat and possible clinical importance. For this intent we correlated MPs with thrombotic pathologies, hemophilia, malaria, diabetes, cardiovascular diseases, endothelial dysfunctions, pulmonary hypertension, ischemic stroke, pre-eclampsia, rheumatologic diseases-rheumatoid arthritis, polymyositis-dermatomyositis, angiogenesis and tumor progression-cancer; we listed the possibilities of using them to improve transfusion methods, as a marker for acute allograft rejection, in stem cell transplantation, as neuronal biomarkers, to understand gender-specific susceptibility for diseases and to improve vaccination methods and we presented some methods for the detection of MPs. PMID:20941744

  20. Enhanced detection of 3D individual trees in forested areas using airborne full-waveform LiDAR data by combining normalized cuts with spatial density clustering

    NASA Astrophysics Data System (ADS)

    Yao, W.; Krzystek, P.; Heurich, M.

    2013-10-01

    A detailed understanding of the spatial distribution of forest understory is important but difficult. LiDAR remote sensing has been developing as a promising additional instrument to the conventional field work towards automated forest inventory. Unfortunately, understory (up to 50% of the top-tree height) in mixed and multilayered forests is often ignored due to a difficult observation scenario and limitation of the tree detection algorithm. Currently, the full-waveform (FWF) LiDAR with high penetration ability against overstory crowns can give us new hope to resolve the forest understory. Former approach based on 3D segmentation confirmed that the tree detection rates in both middle and lower forest layers are still low. Therefore, detecting sub-dominant and suppressed trees cannot be regarded as fully solved. In this work, we aim to improve the performance of the FWF laser scanner for the mapping of forest understory. The paper is to develop an enhanced methodology for detecting 3D individual trees by partitioning point clouds of airborne LiDAR. After extracting 3D coordinates of the laser beam echoes, the pulse intensity and width by waveform decomposition, the newly developed approach resolves 3D single trees are by an integrated approach, which delineates tree crowns by applying normalized cuts segmentation to the graph structure of local dense modes in point clouds constructed by mean shift clustering. In the context of our strategy, the mean shift clusters approximate primitives of (sub) single trees in LiDAR data and allow to define more significant features to reflect geometric and reflectional characteristics towards the single tree level. The developed methodology can be regarded as an object-based point cloud analysis approach for tree detection and is applied to datasets captured with the Riegl LMS-Q560 laser scanner at a point density of 25 points/m2 in the Bavarian Forest National Park, Germany, respectively under leaf-on and leaf-off conditions

  1. Fourth Airborne Geoscience Workshop

    NASA Technical Reports Server (NTRS)

    1991-01-01

    The focus of the workshop was on how the airborne community can assist in achieving the goals of the Global Change Research Program. The many activities that employ airborne platforms and sensors were discussed: platforms and instrument development; airborne oceanography; lidar research; SAR measurements; Doppler radar; laser measurements; cloud physics; airborne experiments; airborne microwave measurements; and airborne data collection.

  2. Cell-derived microparticles and the lung.

    PubMed

    Nieri, Dario; Neri, Tommaso; Petrini, Silvia; Vagaggini, Barbara; Paggiaro, Pierluigi; Celi, Alessandro

    2016-09-01

    Cell-derived microparticles are small (0.1-1 μm) vesicles shed by most eukaryotic cells upon activation or during apoptosis. Microparticles carry on their surface, and enclose within their cytoplasm, molecules derived from the parental cell, including proteins, DNA, RNA, microRNA and phospholipids. Microparticles are now considered functional units that represent a disseminated storage pool of bioactive effectors and participate both in the maintenance of homeostasis and in the pathogenesis of diseases. The mechanisms involved in microparticle generation include intracellular calcium mobilisation, cytoskeleton rearrangement, kinase phosphorylation and activation of the nuclear factor-κB. The role of microparticles in blood coagulation and inflammation, including airway inflammation, is well established in in vitro and animal models. The role of microparticles in human pulmonary diseases, both as pathogenic determinants and biomarkers, is being actively investigated. Microparticles of endothelial origin, suggestive of apoptosis, have been demonstrated in the peripheral blood of patients with emphysema, lending support to the hypothesis that endothelial dysfunction and apoptosis are involved in the pathogenesis of the disease and represent a link with cardiovascular comorbidities. Microparticles also have potential roles in patients with asthma, diffuse parenchymal lung disease, thromboembolism, lung cancer and pulmonary arterial hypertension. PMID:27581826

  3. Airborne Imagery

    NASA Technical Reports Server (NTRS)

    1983-01-01

    ATM (Airborne Thematic Mapper) was developed for NSTL (National Space Technology Companies) by Daedalus Company. It offers expanded capabilities for timely, accurate and cost effective identification of areas with prospecting potential. A related system is TIMS, Thermal Infrared Multispectral Scanner. Originating from Landsat 4, it is also used for agricultural studies, etc.

  4. Hypervelocity microparticle characterization

    SciTech Connect

    Idzorek, G.C.

    1996-11-01

    To protect spacecraft from orbital debris requires a basic understanding of the processes involved in hypervelocity impacts and characterization of detectors to measure the space environment. Both require a source of well characterized hypervelocity particles. Electrostatic acceleration of charged microspheres provides such a source. Techniques refined at the Los Alamos National Laboratory provided information on hypervelocity impacts of particles of known mass and velocity ranging from 20-1000 nm diameter and 1-100 km/s. A Van De Graaff generator operating at 6 million volts was used to accelerate individual carbonyl iron microspheres produced by a specially designed particle source. Standard electrostatic lenses and steering were used to control the particles flight path. Charge sensitive pickoff tubes measured the particle charge and velocity in- flight without disturbing the particle. This information coupled with the measured Van De Graaff terminal voltage allowed calculation of the particle energy, mass, momenta and (using an assumed density) the size. Particles with the desired parameters were then electrostatically directed to a target chamber. Targets used in our experiments included cratering and foil puncture targets, microphone momentum enhancement detectors, triboluminescent detectors, and ``splash`` charge detectors. In addition the system has been used to rapidly characterize size distributions of conductive plastic particles and potentially provide a method of easily sorting microscopic particles by size.

  5. Proteomics of Microparticles with SILAC Quantification (PROMIS-Quan): A Novel Proteomic Method for Plasma Biomarker Quantification*

    PubMed Central

    Harel, Michal; Oren-Giladi, Pazit; Kaidar-Person, Orit; Shaked, Yuval; Geiger, Tamar

    2015-01-01

    Unbiased proteomic analysis of plasma samples holds the promise to reveal clinically invaluable disease biomarkers. However, the tremendous dynamic range of the plasma proteome has so far hampered the identification of such low abundant markers. To overcome this challenge we analyzed the plasma microparticle proteome, and reached an unprecedented depth of over 3000 plasma proteins in single runs. To add a quantitative dimension, we developed PROMIS-Quan—PROteomics of MIcroparticles with Super-Stable Isotope Labeling with Amino Acids in Cell Culture (SILAC) Quantification, a novel mass spectrometry-based technology for plasma microparticle proteome quantification. PROMIS-Quan enables a two-step relative and absolute SILAC quantification. First, plasma microparticle proteomes are quantified relative to a super-SILAC mix composed of cell lines from distinct origins. Next, the absolute amounts of selected proteins of interest are quantified relative to the super-SILAC mix. We applied PROMIS-Quan to prostate cancer and compared plasma microparticle samples of healthy individuals and prostate cancer patients. We identified in total 5374 plasma-microparticle proteins, and revealed a predictive signature of three proteins that were elevated in the patient-derived plasma microparticles. Finally, PROMIS-Quan enabled determination of the absolute quantitative changes in prostate specific antigen (PSA) upon treatment. We propose PROMIS-Quan as an innovative platform for biomarker discovery, validation, and quantification in both the biomedical research and in the clinical worlds. PMID:25624350

  6. Microparticles prepared from sulfenamide-based polymers

    PubMed Central

    D’Mello, Sheetal R.; Yoo, Jun; Bowden, Ned B.; Salem, Aliasger K.

    2015-01-01

    Polysulfenamides (PSN), with a SN linkage (RSNR2) along the polymer backbone, are a new class of biodegradable and biocompatible polymers. These polymers were unknown prior to 2012 when their synthesis and medicinally relevant properties were reported. The aim of this study was to develop microparticles as a controlled drug delivery system using polysulfenamide as the matrix material. The microparticles were prepared by a water-in-oil-in-water double emulsion solvent evaporation method. For producing drug-loaded particles, FITC-dextran was used as a model hydrophilic compound. At the optimal formulation conditions, the external morphology of the PSN microparticles was examined by scanning electron microscopy to show the formation of smooth-surfaced spherical particles with low polydispersity. The microparticles had a net negative surface charge (−23 mV) as analyzed by the zetasizer. The drug encapsulation efficiency of the particles and the drug loading were found to be dependent on the drug molecular weight, amount of FITC-dextran used in fabricating FITC-dextran loaded microparticles, concentration of PSN and surfactant, and volume of the internal and external water phases. FITC-dextran was found to be distributed throughout the PSN microparticles and was released in an initial burst followed by more continuous release over time. Confocal laser scanning microscopy was used to qualitatively observe the cellular uptake of PSN microparticles and indicated localization of the particles in both the cytoplasm and the nucleus. PMID:23862723

  7. Electrodynamic radioactivity detector for microparticles

    NASA Astrophysics Data System (ADS)

    Ward, T. L.; Davis, E. J.; Jenkins, R. W., Jr.; McRae, D. D.

    1989-03-01

    A new technique for the measurement of the radioactive decay of single microparticles has been demonstrated. Although the experiments were made with droplets of order 20 μm in diameter, microparticles in the range 0.1-100 μm can be accommodated. An electrodynamic balance and combination light-scattering photometer were used to measure the charge-loss rate and size of a charged microsphere suspended in a laser beam by superposed ac and dc electrical fields. The charged particle undergoes charge loss in the partially ionized gas atmosphere which results from radioactive decay of 14C-tagged compounds, and the rate of charge loss is proportional to the rate of decay here. The charge on a particle was determined by measuring the dc voltage necessary to stably suspend the particle against gravity while simultaneously determining the droplet size by light-scattering techniques. The parameters which affect the operation of the electrodynamic balance as a radioactivity detector are examined, and the limits of its sensitivity are explored. Radioactivity levels as low as 120 pCi have been measured, and it appears that by reducing the background contamination inside our balance activity levels on the order of 10 pCi can be detected. This new technique has application in the measurement of activity levels and source discrimination of natural and man-made aerosols and smokes and is also useful for studies involving specifically labeled radio-chemical probes.

  8. Airborne Imagery Collections Barrow 2013

    DOE Data Explorer

    Cherry, Jessica; Crowder, Kerri

    2015-07-20

    The data here are orthomosaics, digital surface models (DSMs), and individual frames captured during low altitude airborne flights in 2013 at the Barrow Environmental Observatory. The orthomosaics, thermal IR mosaics, and DSMs were generated from the individual frames using Structure from Motion techniques.

  9. [Penetration of microparticles into human skin].

    PubMed

    Lademann, J; Schaefer, H; Otberg, N; Teichmann, A; Blume-Peytavi, U; Sterry, W

    2004-12-01

    The efficacy of the penetration of microparticles into the human skin depends on the size and the type of the formulation with which they are topically applied. Microparticles with a diameter of >1 microm barely penetrate into the human skin. They are located on the skin surface and form a film which, for instance, can be used for camouflage or protection against UV radiation in sunscreens. While the penetration of the microparticles in the lipid layers of the stratum corneum is limited, they penetrate efficiently into the hair follicles up to a depth >2 mm, providing their diameter is <1.5 microm. Thus, microparticles can be used for drug delivery into the hair follicles.

  10. Cell-derived microparticles circulate in healthy humans and support low grade thrombin generation.

    PubMed

    Berckmans, R J; Nieuwland, R; Böing, A N; Romijn, F P; Hack, C E; Sturk, A

    2001-04-01

    We determined the numbers, cellular origin and thrombin-generating properties of microparticles in healthy individuals (n = 15). Microparticles, isolated from fresh blood samples and identified by flow cytometry, originated from platelets [237 x 10(6)/L (median; range 116-565)], erythrocytes (28 x 10(6)/L; 13-46), granulocytes (46 x 10(6)/L; 16-94) and endothelial cells (64 x 10(6)/L; 16-136). They bound annexin V, indicating surface exposure of phosphatidylserine, and supported coagulation in vitro. Interestingly, coagulation occurred via tissue factor (TF)-independent pathways, because antibodies against TF or factor (F)VII were ineffective. In contrast, in our in vitro experiments coagulation was partially inhibited by antibodies against FXII (12%, p = 0.006), FXI (36%, p <0.001), FIX (28%, p <0.001) or FVIII (32%, p <0.001). Both the number of annexin V-positive microparticles present in plasma and the thrombin-generating capacity inversely correlated to the plasma concentrations of thrombin-antithrombin complex (r = -0.49, p = 0.072 and r = -0.77, p = 0.001, respectively), but did not correlate to prothrombin fragment F1+2 (r = -0.002, p = 0.99). The inverse correlations between the number of microparticles and their thrombin-forming capacity and the levels of thrombin-antithrombin complex in plasma may indicate that microparticles present in the circulation of healthy individuals have an anticoagulant function by promoting the generation of low amounts of thrombin that activate protein C. We conclude that microparticles in blood from healthy individuals support thrombin generation via TF- and FVII-independent pathways, and which may have an anticoagulant function.

  11. Trojan Microparticles for Drug Delivery

    PubMed Central

    Anton, Nicolas; Jakhmola, Anshuman; Vandamme, Thierry F.

    2012-01-01

    During the last decade, the US Food and Drug Administration (FDA) have regulated a wide range of products, (foods, cosmetics, drugs, devices, veterinary, and tobacco) which may utilize micro and nanotechnology or contain nanomaterials. Nanotechnology allows scientists to create, explore, and manipulate materials in nano-regime. Such materials have chemical, physical, and biological properties that are quite different from their bulk counterparts. For pharmaceutical applications and in order to improve their administration (oral, pulmonary and dermal), the nanocarriers can be spread into microparticles. These supramolecular associations can also modulate the kinetic releases of drugs entrapped in the nanoparticles. Different strategies to produce these hybrid particles and to optimize the release kinetics of encapsulated drugs are discussed in this review. PMID:24300177

  12. Optical manipulation of microparticles and biological structures

    NASA Astrophysics Data System (ADS)

    Gahagan, Kevin Thomas

    1998-06-01

    We report experimental and theoretical investigations of the trapping of microparticles and biological objects using radiation pressure. Part I of this thesis presents a technique for trapping both low and high index microparticles using a single, stationary focused laser beam containing an optical vortex. Advantages of this vortex trap include the ease of implementation, a lower exposure level for high-index particles compared to a standard Gaussian beam trap, and the ability to isolate individual low-index particles in concentrated dispersions. The vortex trap is modeled using ray-tracing methods and a more precise electromagnetic model, which is accurate for particles less than 10 μm in diameter. We have measured the stable equilibrium position for two low-index particle systems (e.g., hollow glass spheres (HGS) in water, and water droplets in acetophenone (W/A)). The strength of the trap was measured for the HGS system along the longitudinal and transverse directions. We also demonstrate simultaneous trapping of a low and high index particle with a vortex beam. The stability of this dual-particle trap is found to depend on the relative particle size, the divergence angle of the beam, and the depth of the particles within the trapping chamber. Part II presents results from an interdisciplinary and collaborative investigation of an all-optical genetic engineering technique whereby Agrobacterium rhizogenes were inserted through a laser-ablated hole in the cell wall of the plant, Gingko biloba. We describe a protocol which includes the control of osmotic conditions, culturing procedures, viability assays and laser microsurgery. We succeeded in placing up to twelve viable bacteria into a single plant cell using this technique. The bacteria are believed to be slightly heated by the Gaussian beam trap. A numerical model is presented predicting a temperature rise of just a few degrees. Whereas G. biloba and A. rhitogenes were chosen for this study because of Ginkgo

  13. Circulating microparticles: square the circle

    PubMed Central

    2013-01-01

    Background The present review summarizes current knowledge about microparticles (MPs) and provides a systematic overview of last 20 years of research on circulating MPs, with particular focus on their clinical relevance. Results MPs are a heterogeneous population of cell-derived vesicles, with sizes ranging between 50 and 1000 nm. MPs are capable of transferring peptides, proteins, lipid components, microRNA, mRNA, and DNA from one cell to another without direct cell-to-cell contact. Growing evidence suggests that MPs present in peripheral blood and body fluids contribute to the development and progression of cancer, and are of pathophysiological relevance for autoimmune, inflammatory, infectious, cardiovascular, hematological, and other diseases. MPs have large diagnostic potential as biomarkers; however, due to current technological limitations in purification of MPs and an absence of standardized methods of MP detection, challenges remain in validating the potential of MPs as a non-invasive and early diagnostic platform. Conclusions Improvements in the effective deciphering of MP molecular signatures will be critical not only for diagnostics, but also for the evaluation of treatment regimens and predicting disease outcomes. PMID:23607880

  14. Raman Spectroscopy of Optically Trapped Single Biological Micro-Particles

    PubMed Central

    Redding, Brandon; Schwab, Mark J.; Pan, Yong-le

    2015-01-01

    The combination of optical trapping with Raman spectroscopy provides a powerful method for the study, characterization, and identification of biological micro-particles. In essence, optical trapping helps to overcome the limitation imposed by the relative inefficiency of the Raman scattering process. This allows Raman spectroscopy to be applied to individual biological particles in air and in liquid, providing the potential for particle identification with high specificity, longitudinal studies of changes in particle composition, and characterization of the heterogeneity of individual particles in a population. In this review, we introduce the techniques used to integrate Raman spectroscopy with optical trapping in order to study individual biological particles in liquid and air. We then provide an overview of some of the most promising applications of this technique, highlighting the unique types of measurements enabled by the combination of Raman spectroscopy with optical trapping. Finally, we present a brief discussion of future research directions in the field. PMID:26247952

  15. Biocompatibility of microparticles into soft tissue fillers.

    PubMed

    Laeschke, Klaus

    2004-12-01

    The increasing need for long-lasting injectable soft tissue fillers for the treatment of wrinkles and folds requires a critical discussion of the biocompatibility on a scientific background. Since biological fillers made of collagen and hyaluronic acid will be resorbed over time, copolymer biomaterials with microparticles have been developed in recent years. The microparticles followed special and essential demands because of the interaction with the tissue. In search of an ideal soft tissue filler substance, a variety of biomaterials with microparticles suspended have been created for injecting into dermal defects, into the urethra of patients with urinary incontinence, and in patients with vocal cord insufficiency. The particles differ in chemical composition, surface structure, surface charge, and particle size and evoke different host reactions, accordingly.

  16. Thermoporometry characterization of silica microparticles and nanowires.

    PubMed

    Wu, Jiaxin; Zheng, Han; Cheng, He; Zhou, L; Leong, K C; Rajagopalan, R; Too, H P; Choi, W K

    2014-03-01

    We present the results of a systematic study on the porosity of silica microparticles and nanowires prepared by glancing angle deposition-metal-assisted chemical etching (GLAD-MACE) and interference lithography-metal-assisted chemical etching (IL-MACE) techniques using the thermoporometry (TPM) method. Good agreement was obtained between our TPM results and published data provided by the suppliers of silica microparticles. TPM characterization of the GLAD-MACE and IL-MACE nanowires was carried out on the basis of parameters obtained from TPM experiments on microparticles. Our nanowires showed a similar trend but lower values of the pore volume and surface area than nanowires prepared by MACE with AgNO3 solution. We attribute the enhanced bioanalysis performance of the GLAD-MACE nanowires based devices to the increased pore volume and total surface area of the nanowires.

  17. Injectable macroporous microparticles for soft tissue augmentation.

    PubMed

    Corrin, Abigail A; Ngai, Matthew; Walthers, Christopher M; Dunn, James C Y; Wu, Benjamin M

    2012-01-01

    Macroporous polymeric microparticles have been fabricated using a combination of particulate leaching and gas foaming techniques. Controlling the concentration of ammonium bicarbonate particles and the spin speed of the microemulsion in poly (ε-caprolactone) (PCL) yields a range of macroporous microparticles with interconnected pores (10-50 µm) that may promote cell and tissue ingrowth in vivo when implanted subcutaneously. This fabrication technique introduces a novel template which can be modified to meet a diverse set of material and biological specifications. PMID:23366415

  18. Ordering of solid microparticles at liquid crystal-water interfaces.

    PubMed

    Lin, I-Hsin; Koenig, Gary M; de Pablo, Juan J; Abbott, Nicholas L

    2008-12-25

    We report a study of the organization of solid microparticles at oil-water interfaces, where the oil is a thermotropic liquid crystal (LC). The study was motivated by the proposition that microparticle organization and LC ordering would be coupled at these interfaces. Surfactant-functionalized polystyrene microparticles were spread at air-water interfaces at prescribed densities and then raised into contact with supported films of nematic 4-pentyl-4'-cyanobiphenyl (5CB). Whereas this method of sample preparation led to quantitative transfer of microparticles from the air-water interface to an isotropic oil-water interface, forces mediated by the nematic order of 5CB were observed to rapidly displace microparticles laterally across the interface of the water upon contact with nematic 5CB, thus leading to a 65% decrease in the density of microparticles at the LC-water interface. These lateral forces were determined to be caused by microparticle-induced deformation of the LC, the energy of which was estimated to be approximately 10(4) kT. We also observed microparticles transferred to the LC-water interface to assemble into chainlike structures that were not seen when using isotropic oils, indicating the presence of LC-mediated interparticle interactions at this interface. Optical textures of the LC in the vicinity of the microparticles were consistent with formation of topological defects with dipolar symmetry capable of promoting the chaining of the microparticles. The presence of microparticles at the interface also impacted the ordering of the LCs, including a transition from parallel to perpendicular ordering of the LC with increasing microparticle density. These observations, when combined, demonstrate that LC-mediated interactions can direct the assembly of solid microparticles at LC-water interfaces and that the ordering of the LC is also strongly coupled to the presence of microparticles.

  19. Hydrophobicity of silver surfaces with microparticle geometry

    NASA Astrophysics Data System (ADS)

    Macko, Ján; Oriňaková, Renáta; Oriňak, Andrej; Kovaľ, Karol; Kupková, Miriam; Erdélyi, Branislav; Kostecká, Zuzana; Smith, Roger M.

    2016-11-01

    The effect of the duration of the current deposition cycle and the number of current pulses on the geometry of silver microstructured surfaces and on the free surface energy, polarizability, hydrophobicity and thus adhesion force of the silver surfaces has been investigated. The changes in surface hydrophobicity were entirely dependent on the size and density of the microparticles on the surface. The results showed that formation of the silver microparticles was related to number of current pulses, while the duration of one current pulse played only a minor effect on the final surface microparticle geometry and thus on the surface tension and hydrophobicity. The conventional geometry of the silver particles has been transformed to the fractal dimension D. The surface hydrophobicity depended predominantly on the length of the dendrites not on their width. The highest silver surface hydrophobicity was observed on a surface prepared by 30 current pulses with a pulse duration of 1 s, the lowest one when deposition was performed by 10 current pulses with a duration of 0.1 s. The partial surface tension coefficients γDS and polarizability kS of the silver surfaces were calculated. Both parameters can be applied in future applications in living cells adhesion prediction and spectral method selection. Silver films with microparticle geometry showed a lower variability in final surface hydrophobicity when compared to nanostructured surfaces. The comparisons could be used to modify surfaces and to modulate human cells and bacterial adhesion on body implants, surgery instruments and clean surfaces.

  20. Laser-induced hybrid trap for microparticles

    NASA Astrophysics Data System (ADS)

    Wang, Yuzhu; Ni, H. Q.; Li, Yong Qing; Xu, Yuguang; Lu, Baolong; Shao, Wei

    1992-10-01

    This paper reports the observation of stable trapping of a transparent microparticle. The trap is a light induced hybrid one which consists of both light pressure force and fluid force. A theoretical analysis and experimental results are given. The possible applications are also discussed.

  1. Emergent properties in experiments with active microparticles

    NASA Astrophysics Data System (ADS)

    Palacci, Jeremie

    Self-propelled micro-particles are intrinsically out-of-equilibrium. This renders their physics far richer than passive colloids and give rise to the emergence of complex phenomena e.g. collective behavior, swarming... I will present experimental demonstration of emergent properties beyond equilibrium.

  2. In situ gelling hydrogels incorporating microparticles as drug delivery carriers for regenerative medicine.

    PubMed

    Hou, Qingpu; Chau, David Y S; Pratoomsoot, Chayanin; Tighe, Patrick J; Dua, Harminder S; Shakesheff, Kevin M; Rose, Felicity R A J

    2008-09-01

    Aqueous solutions of blends of biodegradable triblock copolymers, composed of poly(D,L-lactide-co-glycolide) (PLGA) and poly(ethylene glycol) (PEG) with varied D,L-lactide to glycolide ratios, displayed thermosensitivity and formed a gel at body temperature. The gel window of the blend solutions could be tuned by varying the blending ratio between the two components. Furthermore, the storage modulus of the resultant hydrogel from the copolymer blends at body temperature was higher than that of each individual component. Incorporation of poly(D,L-lactide) (PDLLA) microparticles (0.5-40% w/v) within the in situ gelling hydrogel did not change the sol-gel transition temperatures of the polymer solutions, while the mechanical strength of the resultant hydrogels was enhanced when the content of the microparticles was increased up to 30% and 40%. Incorporation of proteins into both the gel and microparticle components resulted in composites that controlled the kinetics of protein release. Protein within the gel phase was released over a 10-day period whilst protein in the microparticles was released over a period of months. This system can be used to deliver two drugs with differing release kinetics and could be used to orchestrate tissue regeneration responses over differing timescales. PMID:18240277

  3. Real-time dynamics of high-velocity micro-particle impact

    NASA Astrophysics Data System (ADS)

    Veysset, David; Hsieh, Alex; Kooi, Steve; Maznev, Alex A.; Tang, Shengchang; Olsen, Bradley D.; Nelson, Keith A.

    High-velocity micro-particle impact is important for many areas of science and technology, from space exploration to the development of novel drug delivery platforms. We present real-time observations of supersonic micro-particle impacts using multi-frame imaging. In an all optical laser-induced projectile impact test, a monolayer of micro-particles is placed on a transparent substrate coated with a laser absorbing polymer layer. Ablation of a laser-irradiated polymer region accelerates the micro-particles into free space with speeds up to 1.0 km/s. The particles are monitored during the impact on the target with an ultrahigh-speed multi-frame camera that can record up to 16 images with time resolution as short as 3 ns. In particular, we investigated the high-velocity impact deformation response of poly(urethane urea) (PUU) elastomers to further the fundamental understanding of the molecular influence on dynamical behaviors of PUUs. We show the dynamic-stiffening response of the PUUs and demonstrate the significance of segmental dynamics in the response. We also present movies capturing individual particle impact and penetration in gels, and discuss the observed dynamics. The results will provide an impetus for modeling high-velocity microscale impact responses and high strain rate deformation in polymers, gels, and other materials.

  4. Statistics for motion of microparticles in a plasma

    NASA Astrophysics Data System (ADS)

    Mukhopadhyay, Amit Kumar

    I report experimental and numerical studies of microparticle motion in a dusty plasma. These microparticles are negatively charged and are levitated in a plasma consisting of electrons, ions and neutral gas atoms. The microparticles repel each other, and are confined by the electric fields in the plasma. The neutral gas damps the microparticle motion, and also exerts random forces on them. I investigate and characterize microparticle motion. In order to do this, I study velocity distributions of microparticles and correlations of their motion. To perform such a study, I develop new experimental and analysis techniques. My thesis consists of four separate projects. In the first project, the battle between deterministic and random motion of microparticles is investigated. Two particle velocity distributions and correlations have previously studied only in theory. I performed an experiment with a very simple one dimensional (1D) system of two microparticles in a plasma. My study of velocity correlations involves just two microparticles which is the simplest system that allows interactions. A study of such a simple system provides insight into the motions of the microparticles. It allowed for the experimental measurement of two-particle distributions and correlations. For such a system, it is shown that the motion of the microparticles is dominated by deterministic or oscillatory effects. In the second project, two experiments with just two microparticles are performed to isolate the effects of ion wakes. The two experiments differ in the alignment of the two microparticles: they are aligned either perpendicular or parallel to the ion flow. To have different alignments, the sheath is shaped differently in the two experiments. I demonstrate that microparticle motion is more correlated when they are aligned along the ion flow, rather than perpendicular to the ion flow. In the third project, I develop a model with some key assumptions to compare with the experiments in

  5. Encapsulation of sorbitan ester-based organogels in alginate microparticles.

    PubMed

    Sagiri, Sai S; Pal, Kunal; Basak, Piyali; Rana, Usman Ali; Shakir, Imran; Anis, Arfat

    2014-10-01

    Leaching of the internal apolar phase from the biopolymeric microparticles during storage is a great concern as it undoes the beneficial effects of encapsulation. In this paper, a novel formulation was prepared by encapsulating the sunflower oil-based organogels in alginate microparticles. Salicylic acid and metronidazole were used as the model drugs. The microparticles were prepared by double emulsion methodology. Physico-chemical characterization of the microparticles was done by microscopy, FTIR, XRD, and DSC studies. Oil leaching studies, biocompatibility, mucoadhesivity, in vitro drug release, and the antimicrobial efficiency of the microparticles were also performed. The microparticles were found to be spherical in shape. Gelation of the sunflower oil prevented leaching of the internal phase from the microparticles. Release of drugs from the microparticles followed Fickian kinetics and non-Fickian kinetics in gastric and intestinal environments, respectively. Microparticles showed good antimicrobial activity against both Gram-positive (Bacillus subtilis) and Gram-negative (Escherichia coli) bacteria. The results suggested that the developed formulations hold promise to carry oils without leakage of the internal phase. Encapsulation of organogels within the microparticles has improved the drug entrapment efficiency and improved characteristics for controlled delivery applications.

  6. Heterogeneity in Neutrophil Microparticles Reveals Distinct Proteome and Functional Properties*

    PubMed Central

    Dalli, Jesmond; Montero-Melendez, Trinidad; Norling, Lucy V; Yin, Xiaoke; Hinds, Charles; Haskard, Dorian; Mayr, Manuel; Perretti, Mauro

    2013-01-01

    Altered plasma neutrophil microparticle levels have recently been implicated in a number of vascular and inflammatory diseases, yet our understanding of their actions is very limited. Herein, we investigate the proteome of neutrophil microparticles in order to shed light on their biological actions. Stimulation of human neutrophils, either in suspension or adherent to an endothelial monolayer, led to the production of microparticles containing >400 distinct proteins with only 223 being shared by the two subsets. For instance, postadherent microparticles were enriched in alpha-2 macroglobulin and ceruloplasmin, whereas microparticles produced by neutrophils in suspension were abundant in heat shock 70 kDa protein 1. Annexin A1 and lactotransferrin were expressed in both microparticle subsets. We next determined relative abundance of these proteins in three types of human microparticle samples: healthy volunteer plasma, plasma of septic patients and skin blister exudates finding that these proteins were differentially expressed on neutrophil microparticles from these samples reflecting in part the expression profiles we found in vitro. Functional assessment of the neutrophil microparticles subsets demonstrated that in response to direct stimulation neutrophil microparticles produced reactive oxygen species and leukotriene B4 as well as locomoted toward a chemotactic gradient. Finally, we investigated the actions of the two neutrophil microparticles subsets described herein on target cell responses. Microarray analysis with human primary endothelial cells incubated with either microparticle subset revealed a discrete modulation of endothelial cell gene expression profile. These findings demonstrate that neutrophil microparticles are heterogenous and can deliver packaged information propagating the activation status of the parent cell, potentially exerting novel and fundamental roles both under homeostatic and disease conditions. PMID:23660474

  7. Aerogel Microparticles from Oil-in-Oil Emulsion Systems.

    PubMed

    Gu, Senlong; Zhai, Chunhao; Jana, Sadhan C

    2016-06-01

    This paper reports preparation of polymer aerogel microparticles via sol-gel reactions inside micrometer size droplets created in an oil-in-oil emulsion system. The oil-in-oil emulsion system is obtained by dispersing in cyclohexane the droplets of the sols of polybenzoxazine (PBZ) or polyimide (PI) prepared in dimethylformamide. The sol droplets transform into harder gel microparticles due to sol-gel reactions. Finally, the aerogel microparticles are recovered using supercritical drying of the gel microparticles. The PBZ and PI aerogel microparticles prepared in this manner show mean diameter 32.7 and 40.0 μm, respectively, mesoporous internal structures, and surface area 55.4 and 512.0 m(2)/g, respectively. Carbonization of PBZ aerogel microparticles maintains the mesoporous internal structures but yields narrower pore size distribution. PMID:27183146

  8. Aerogel Microparticles from Oil-in-Oil Emulsion Systems.

    PubMed

    Gu, Senlong; Zhai, Chunhao; Jana, Sadhan C

    2016-06-01

    This paper reports preparation of polymer aerogel microparticles via sol-gel reactions inside micrometer size droplets created in an oil-in-oil emulsion system. The oil-in-oil emulsion system is obtained by dispersing in cyclohexane the droplets of the sols of polybenzoxazine (PBZ) or polyimide (PI) prepared in dimethylformamide. The sol droplets transform into harder gel microparticles due to sol-gel reactions. Finally, the aerogel microparticles are recovered using supercritical drying of the gel microparticles. The PBZ and PI aerogel microparticles prepared in this manner show mean diameter 32.7 and 40.0 μm, respectively, mesoporous internal structures, and surface area 55.4 and 512.0 m(2)/g, respectively. Carbonization of PBZ aerogel microparticles maintains the mesoporous internal structures but yields narrower pore size distribution.

  9. Motion of a group of microparticles in a viscoelastic medium under the action of acoustic radiation force

    NASA Astrophysics Data System (ADS)

    Andreev, V. G.; Shanin, A. V.; Demin, I. Yu.

    2014-11-01

    We theoretically and experimentally substantiate the method of detecting microcalcifications in mammary gland tissue. Calcium salts accumulate in soft tissues, primarily forming clusters of individual microparticles. We study the motion of solid microparticles distributed in a viscoelastic medium. Displacement of particles is caused by the radiation force occurring as a consequence of energy scattering and absorption of an ultrasound beam focused in the particle region. The radiation force acts over the course of 200 μs, after which the medium with distributed particles relaxes to the initial state. Motion of the medium is tracked by the cross-correlation method with short probing pulses following at a frequency of 5 kHz. The presence of solid microparticles leads to a change in the character of motion of the medium after pulsed ultrasound action. The amplitude and duration of displacements increases in comparison to the homogeneous medium, and the motion character itself becomes significantly complicated.

  10. BioAerosol Mass Spectrometry: Reagentless Detection of Individual Airborne Spores and Other Bioagent Particles Based on Laser Desorption/Ionization Mass Spectrometry

    SciTech Connect

    Steele, Paul Thomas

    2004-09-01

    Better devices are needed for the detection of aerosolized biological warfare agents. Advances in the ongoing development of one such device, the BioAerosol Mass Spectrometry (BAMS) system, are described here in detail. The system samples individual, micrometer-sized particles directly from the air and analyzes them in real-time without sample preparation or use of reagents. At the core of the BAMS system is a dual-polarity, single-particle mass spectrometer with a laser based desorption and ionization (DI) system. The mass spectra produced by early proof-of-concept instruments were highly variable and contained limited information to differentiate certain types of similar biological particles. The investigation of this variability and subsequent changes to the DI laser system are described. The modifications have reduced the observed variability and thereby increased the usable information content in the spectra. These improvements would have little value without software to analyze and identify the mass spectra. Important improvements have been made to the algorithms that initially processed and analyzed the data. Single particles can be identified with an impressive level of accuracy, but to obtain significant reductions in the overall false alarm rate of the BAMS instrument, alarm decisions must be made dynamically on the basis of multiple analyzed particles. A statistical model has been developed to make these decisions and the resulting performance of a hypothetical BAMS system is quantitatively predicted. The predictions indicate that a BAMS system, with reasonably attainable characteristics, can operate with a very low false alarm rate (orders of magnitude lower than some currently fielded biodetectors) while still being sensitive to small concentrations of biological particles in a large range of environments. Proof-of-concept instruments, incorporating some of the modifications described here, have already performed well in independent testing.

  11. Therapeutic strategies based on polymeric microparticles.

    PubMed

    Vilos, C; Velasquez, L A

    2012-01-01

    The development of the field of materials science, the ability to perform multidisciplinary scientific work, and the need for novel administration technologies that maximize therapeutic effects and minimize adverse reactions to readily available drugs have led to the development of delivery systems based on microencapsulation, which has taken one step closer to the target of personalized medicine. Drug delivery systems based on polymeric microparticles are generating a strong impact on preclinical and clinical drug development and have reached a broad development in different fields supporting a critical role in the near future of medical practice. This paper presents the foundations of polymeric microparticles based on their formulation, mechanisms of drug release and some of their innovative therapeutic strategies to board multiple diseases.

  12. Porphyrin Microparticles for Biological and Biomedical Applications

    NASA Astrophysics Data System (ADS)

    Huynh, Elizabeth

    Lipids are one of the critical building blocks of life, forming the plasma membrane of cells. In addition, porphyrins also play an equally important role in life, for example, through carrying oxygen in blood. The importance of both these components is evident through the biological and biomedical applications of supramolecular structures generated from lipids and porphyrins. This thesis investigates new porphyrin microparticles based on porphyrin-lipid architecture and their potential applications in biology and medicine. In Chapter 1, a background on lipid and porphyrin-based supramolecular structures is presented and design considerations for generating multifunctional agents. Chapter 2 describes the generation of a monolayer porphyrin microparticle as a dual-modal ultrasound and photoacoustic contrast agent and subsequently, a trimodal ultrasound, photoacoustic and fluorescence contrast agent. Chapter 3 examines the optical and morphological response of these multimodality ultrasound-based contrast agents to low frequency, high duty cycle ultrasound that causes the porphyrin microparticles to convertinto nanoparticles. Chapter 4 examines the generation of bilayer micrometer-sized porphyrin vesicles and their properties. Chapter 5 presents a brief summary and potential future directions. Although these microscale structures are similar in structure, the applications of these structures greatly differ with potential applications in biology and also imaging and therapy of disease. This thesis aims to explore and demonstrate the potential of new simplified, supramolecular structures based on one main building block, porphyrin-lipid.

  13. Micro-particle manipulation by single beam acoustic tweezers based on hydrothermal PZT thick film

    PubMed Central

    Zhu, Benpeng; Xu, Jiong; Li, Ying; Wang, Tian; Xiong, Ke; Lee, Changyang; Yang, Xiaofei; Shiiba, Michihisa; Takeuchi, Shinichi; Zhou, Qifa; Shung, K. Kirk

    2016-01-01

    Single-beam acoustic tweezers (SBAT), used in laboratory-on-a-chip (LOC) device has promising implications for an individual micro-particle contactless manipulation. In this study, a freestanding hydrothermal PZT thick film with excellent piezoelectric property (d33 = 270pC/N and kt = 0.51) was employed for SBAT applications and a press-focusing technology was introduced. The obtained SBAT, acting at an operational frequency of 50MHz, a low f-number (∼0.9), demonstrated the capability to trap and manipulate a micro-particle sized 10μm in the distilled water. These results suggest that such a device has great potential as a manipulator for a wide range of biomedical and chemical science applications. PMID:27014504

  14. Micro-particle manipulation by single beam acoustic tweezers based on hydrothermal PZT thick film

    NASA Astrophysics Data System (ADS)

    Zhu, Benpeng; Xu, Jiong; Li, Ying; Wang, Tian; Xiong, Ke; Lee, Changyang; Yang, Xiaofei; Shiiba, Michihisa; Takeuchi, Shinichi; Zhou, Qifa; Shung, K. Kirk

    2016-03-01

    Single-beam acoustic tweezers (SBAT), used in laboratory-on-a-chip (LOC) device has promising implications for an individual micro-particle contactless manipulation. In this study, a freestanding hydrothermal PZT thick film with excellent piezoelectric property (d33 = 270pC/N and kt = 0.51) was employed for SBAT applications and a press-focusing technology was introduced. The obtained SBAT, acting at an operational frequency of 50MHz, a low f-number (˜0.9), demonstrated the capability to trap and manipulate a micro-particle sized 10μm in the distilled water. These results suggest that such a device has great potential as a manipulator for a wide range of biomedical and chemical science applications.

  15. Cellular origin and procoagulant properties of microparticles in meningococcal sepsis.

    PubMed

    Nieuwland, R; Berckmans, R J; McGregor, S; Böing, A N; Romijn, F P; Westendorp, R G; Hack, C E; Sturk, A

    2000-02-01

    Patients with meningococcal sepsis generally suffer from disseminated intravascular coagulation (DIC). The aim of this study was to address whether these patients have elevated numbers of circulating microparticles that contribute to the development of DIC. Plasma samples from 5 survivors, 2 nonsurvivors, and 5 healthy volunteers were analyzed for the presence of microparticles by flow cytometry. Ongoing coagulation activation in vivo was quantified by enzyme-linked immunosorbent assay of plasma prothrombin fragment F(1 + 2), and procoagulant properties of microparticles in vitro were estimated by thrombin-generation assay. On admission, all patients had increased numbers of microparticles originating from platelets or granulocytes when compared with controls (P =.004 and P =.008, respectively). Patients had elevated levels of F(1 + 2) (P =.004), and their microparticles supported thrombin generation more strongly in vitro (P =.003) than those of controls. Plasma from the patient with the most fulminant disease course and severe DIC contained microparticles that expressed both CD14 and tissue factor, and these microparticles demonstrated extreme thrombin generation in vitro. We conclude that patients with meningococcal sepsis have elevated numbers of circulating microparticles that are procoagulant. These findings may suggest a novel therapeutic approach to combat clinical conditions with excessive coagulation activation.

  16. Cavitational Iron Microparticles Generation By Plasma Procedures For Medical Applications

    NASA Astrophysics Data System (ADS)

    Bica, Ioan; Bunoiu, Madalin; Chirigiu, Liviu; Spunei, Marius; Juganaru, Iulius

    2012-12-01

    The paper presents the experimental installation for the production, in argon plasma, of cavitational iron microparticles (pore microspheres, microtubes and octopus-shaped microparticles). Experimental results are presented and discussed and it is shown that absorbant particles with a minimum iron content are obtained by the plasma procedures

  17. Highly Loaded, Sustained-Release Microparticles of Curcumin for Chemoprevention

    PubMed Central

    SHAHANI, KOMAL; PANYAM, JAYANTH

    2014-01-01

    Curcumin, a dietary polyphenol, has preventive and therapeutic potential against several diseases. Because of the chronic nature of many of these diseases, sustained-release dosage forms of curcumin could be of significant clinical value. However, extreme lipophilicity and instability of curcumin are significant challenges in its formulation development. The objectives of this study were to fabricate an injectable microparticle formulation that can sustain curcumin release over a 1-month period and to determine its chemopreventive activity in a mouse model. Microparticles were fabricated using poly(D, L-lactide-co-glycolide) polymer. Conventional emulsion solvent evaporation method of preparing microparticles resulted in crystallization of curcumin outside of microparticles and poor entrapment (~1%, w/w loading). Rapid solvent removal using vacuum dramatically increased drug entrapment (~38%, w/w loading; 76% encapsulation efficiency). Microparticles sustained curcumin release over 4 weeks in vitro, and drug release rate could be modulated by varying the polymer molecular weight and/or composition. A single subcutaneous dose of microparticles sustained curcumin liver concentration for nearly a month in mice. Hepatic glutathione-s-transferase and cyclooxygenase-2 activities, biomarkers for chemoprevention, were altered following treatment with curcumin microparticles. The results of these studies suggest that sustained-release microparticles of curcumin could be a novel and effective approach for cancer chemoprevention. PMID:21547911

  18. Shear stress-induced mitochondrial biogenesis decreases the release of microparticles from endothelial cells

    PubMed Central

    Kim, Ji-Seok; Kim, Boa; Lee, Hojun; Thakkar, Sunny; Babbitt, Dianne M.; Eguchi, Satoru; Brown, Michael D.

    2015-01-01

    The concept of enhancing structural integrity of mitochondria has emerged as a novel therapeutic option for cardiovascular disease. Flow-induced increase in laminar shear stress is a potent physiological stimulant associated with exercise, which exerts atheroprotective effects in the vasculature. However, the effect of laminar shear stress on mitochondrial remodeling within the vascular endothelium and its related functional consequences remain largely unknown. Using in vitro and in vivo complementary studies, here, we report that aerobic exercise alleviates the release of endothelial microparticles in prehypertensive individuals and that these salutary effects are, in part, mediated by shear stress-induced mitochondrial biogenesis. Circulating levels of total (CD31+/CD42a−) and activated (CD62E+) microparticles released by endothelial cells were significantly decreased (∼40% for both) after a 6-mo supervised aerobic exercise training program in individuals with prehypertension. In cultured human endothelial cells, laminar shear stress reduced the release of endothelial microparticles, which was accompanied by an increase in mitochondrial biogenesis through a sirtuin 1 (SIRT1)-dependent mechanism. Resveratrol, a SIRT1 activator, treatment showed similar effects. SIRT1 knockdown using small-interfering RNA completely abolished the protective effect of shear stress. Disruption of mitochondrial integrity by either antimycin A or peroxisome proliferator-activated receptor-γ coactivator-1α small-interfering RNA significantly increased the number of total, and activated, released endothelial microparticles, and shear stress restored these back to basal levels. Collectively, these data demonstrate a critical role of endothelial mitochondrial integrity in preserving endothelial homeostasis. Moreover, prolonged laminar shear stress, which is systemically elevated during aerobic exercise in the vessel wall, mitigates endothelial dysfunction by promoting mitochondrial

  19. [Endothelial microparticles (EMP) in physiology and pathology].

    PubMed

    Sierko, Ewa; Sokół, Monika; Wojtukiewicz, Marek Z

    2015-08-18

    Endothelial microparticles (EMP) are released from endothelial cells (ECs) in the process of activation and/or apoptosis. They harbor adhesive molecules, enzymes, receptors and cytoplasmic structures and express a wide range of various constitutive antigens, typical for ECs, at their surface. Under physiological conditions the concentration of EMP in the blood is clinically insignificant. However, it was reported that under pathological conditions EMP concentration in the blood might slightly increase and contribute to blood coagulation, angiogenesis and inflammation. It has been shown that EMP directly and indirectly contribute to the activation of blood coagulation. Endothelial microparticles directly participate in blood coagulation through their surface tissue factor (TF) - a major initiator of blood coagulation. Furthermore, EMP exhibit procoagulant potential via expression of negatively charged phospholipids at their surface, which may promote assembly of coagulation enzymes (TF/VII, tenases and prothrombinase complexes), leading to thrombus formation. In addition, they provide a binding surface for coagulation factors: IXa, VIII, Va and IIa. Moreover, it is possible that EMP transfer TF from TF-bearing EMP to activated platelets and monocytes by binding them through adhesion molecules. Also, EMP express von Willebrand factor, which may facilitate platelet aggregation. Apart from their procoagulant properties, it was demonstrated that EMP may express adhesive molecules and metalloproteinases (MMP-2, MMP-9) at their surface and release growth factors, which may contribute to angiogenesis. Additionally, surface presence of C3 and C4 - components of the classical pathway - suggests pro-inflammatory properties of these structures. This article contains a summary of available data on the biology and pathophysiology of endothelial microparticles and their potential role in blood coagulation, angiogenesis and inflammation.

  20. Circulating microparticles in systemic Lupus Erythematosus.

    PubMed

    Nielsen, Christoffer Tandrup

    2012-11-01

    Systemic lupus erythematosus (SLE) is a systemic autoimmune disease presenting with a wide array of clinical manifestations and an elusive pathogenesis. A characteristic feature in SLE is the occurrence of autoantibodies against chromatin, double-stranded DNA, and RNA-binding ribonucleoproteins. Observations of defective clearance of dying cells in SLE combined with the generation and exposure of nuclear autoantigens during apoptosis have led to the hypothesis that improperly cleared apoptotic debris constitutes a source of autoantigens capable of triggering autoimmune disease. In blood, circulating, heterogeneous subcellular microparticles (MPs) are released from cells and platelets constitutively and upon cellular activation or apoptosis. Such MPs may reflect the state of their parental cells and tissues, and could serve as markers of pathology. Particular in SLE MPs may serve as carriers of autoantigens and constituents of immune complexes (ICs). The purposes of this PhD thesis were to develop and apply qualitative and quantitative methods to characterize circulating MPs with respect to numbers, cellular origins and composition in a large cohort of well-characterized SLE patients compared to healthy and disease controls and to explore associations with clinical, biochemical and serological parameters. The PhD thesis consists of a review and three papers. In the first paper we show that SLE patients have significantly decreased numbers of annexin V binding MPs and MPs from platelets, leukocytes and endothelial cells using flow cytometry. Two morphologically distinguishable populations of annexin V non-binding MPs were increased in the SLE patients. The annexin V non-binding MPs of most likely cellular origin were associated with the presence of lupus nephritis, markers of increased disease activity and levels of endothelial cell-derived MPs. In the second paper we present the development of a proteomic method to characterize the protein composition of purified

  1. NASA Student Airborne Research Program

    NASA Astrophysics Data System (ADS)

    Schaller, E. L.; Shetter, R. E.

    2012-12-01

    The NASA Student Airborne Research Program (SARP) is a unique summer internship program for advanced undergraduates and early graduate students majoring in the STEM disciplines. SARP participants acquire hands-on research experience in all aspects of an airborne research campaign, including flying onboard an major NASA resource used for studying Earth system processes. In summer 2012, thirty-two participants worked in four interdisciplinary teams to study surface, atmospheric, and oceanographic processes. Participants assisted in the operation of instruments onboard the NASA P-3B aircraft where they sampled and measured atmospheric gases and imaged land and water surfaces in multiple spectral bands. Along with airborne data collection, students participated in taking measurements at field sites. Mission faculty and research mentors helped to guide participants through instrument operation, sample analysis, and data reduction. Over the eight-week program, each student developed an individual research project from the data collected and delivered a conference-style final presentation on his/her results. We will discuss the results and effectiveness of the program from the first four summers and discuss plans for the future.

  2. Laser ablation of a Terfenol-D microparticle aerosol and subsequent supersonic nanoparticle impaction for magnetostrictive thick films

    NASA Astrophysics Data System (ADS)

    O'Brien, Daniel Thomas

    This dissertation describes using microparticles of the (giant) magnetostrictive material Terfenol-D (Tb0.3Dy0.7Fe1.92) in the Laser Ablation of Microparticle (LAM) aerosols process for the generation of nanoparticles and their subsequent supersonic impaction to form nanostructured magnetostrictive thick films. Solid Terfenol-D was ground to a powder having diameters from 0.3 to 3 mum. This microparticle powder was then aerosolized and ablated by a KrF ultraviolet, pulsed laser in a continuously flowing aerosol process. The nanoparticles formed from the ablation were then accelerated through a supersonic nozzle into vacuum where they impacted onto a substrate at room temperature forming a film. The nanoparticles were amorphous, as shown by x-ray diffraction analysis of the deposited films and by Transmission Electron Microscopy of individual particles, and had a size distribution typical of the LAM process: 3 to 20 nm in diameter with a mean size less than 10 nm. The deposited films were characterized using the cantilever method to determine magnetostriction and elastic modulus. Values of magnetostriction were on the order of 15 ppm for LAM deposited films. The films were porous, due to their granular nature, reducing the elastic modulus to about 15 GPa. The reduced magnetostriction (1/30 that of comparable thin films) was due to oxidation. Spectroscopic analysis of the ablation plasma provided data in determining the source of the oxidation. Calculations showed that the extent of oxidation in the films was dependent on the microparticle feedstock size. For typical aerosol densities used in the LAM process, calculations showed that material made from microparticles having a diameter larger than 3 mum was not significantly affected by background gas impurities or by an oxide shell on the microparticles, whereas 0.3 mum diameter microparticles resulted in completely oxidized nanoparticles and hence films that were completely oxidized. From the behavior of the

  3. Structural and functional characterization of endothelial microparticles released by cigarette smoke.

    PubMed

    Serban, Karina A; Rezania, Samin; Petrusca, Daniela N; Poirier, Christophe; Cao, Danting; Justice, Matthew J; Patel, Milan; Tsvetkova, Irina; Kamocki, Krzysztof; Mikosz, Andrew; Schweitzer, Kelly S; Jacobson, Sean; Cardoso, Angelo; Carlesso, Nadia; Hubbard, Walter C; Kechris, Katerina; Dragnea, Bogdan; Berdyshev, Evgeny V; McClintock, Jeanette; Petrache, Irina

    2016-01-01

    Circulating endothelial microparticles (EMPs) are emerging as biomarkers of chronic obstructive pulmonary disease (COPD) in individuals exposed to cigarette smoke (CS), but their mechanism of release and function remain unknown. We assessed biochemical and functional characteristics of EMPs and circulating microparticles (cMPs) released by CS. CS exposure was sufficient to increase microparticle levels in plasma of humans and mice, and in supernatants of primary human lung microvascular endothelial cells. CS-released EMPs contained predominantly exosomes that were significantly enriched in let-7d, miR-191; miR-126; and miR125a, microRNAs that reciprocally decreased intracellular in CS-exposed endothelium. CS-released EMPs and cMPs were ceramide-rich and required the ceramide-synthesis enzyme acid sphingomyelinase (aSMase) for their release, an enzyme which was found to exhibit significantly higher activity in plasma of COPD patients or of CS-exposed mice. The ex vivo or in vivo engulfment of EMPs or cMPs by peripheral blood monocytes-derived macrophages was associated with significant inhibition of efferocytosis. Our results indicate that CS, via aSMase, releases circulating EMPs with distinct microRNA cargo and that EMPs affect the clearance of apoptotic cells by specialized macrophages. These targetable effects may be important in the pathogenesis of diseases linked to endothelial injury and inflammation in smokers. PMID:27530098

  4. Structural and functional characterization of endothelial microparticles released by cigarette smoke

    PubMed Central

    Serban, Karina A.; Rezania, Samin; Petrusca, Daniela N.; Poirier, Christophe; Cao, Danting; Justice, Matthew J.; Patel, Milan; Tsvetkova, Irina; Kamocki, Krzysztof; Mikosz, Andrew; Schweitzer, Kelly S.; Jacobson, Sean; Cardoso, Angelo; Carlesso, Nadia; Hubbard, Walter C.; Kechris, Katerina; Dragnea, Bogdan; Berdyshev, Evgeny V.; McClintock, Jeanette; Petrache, Irina

    2016-01-01

    Circulating endothelial microparticles (EMPs) are emerging as biomarkers of chronic obstructive pulmonary disease (COPD) in individuals exposed to cigarette smoke (CS), but their mechanism of release and function remain unknown. We assessed biochemical and functional characteristics of EMPs and circulating microparticles (cMPs) released by CS. CS exposure was sufficient to increase microparticle levels in plasma of humans and mice, and in supernatants of primary human lung microvascular endothelial cells. CS-released EMPs contained predominantly exosomes that were significantly enriched in let-7d, miR-191; miR-126; and miR125a, microRNAs that reciprocally decreased intracellular in CS-exposed endothelium. CS-released EMPs and cMPs were ceramide-rich and required the ceramide-synthesis enzyme acid sphingomyelinase (aSMase) for their release, an enzyme which was found to exhibit significantly higher activity in plasma of COPD patients or of CS-exposed mice. The ex vivo or in vivo engulfment of EMPs or cMPs by peripheral blood monocytes-derived macrophages was associated with significant inhibition of efferocytosis. Our results indicate that CS, via aSMase, releases circulating EMPs with distinct microRNA cargo and that EMPs affect the clearance of apoptotic cells by specialized macrophages. These targetable effects may be important in the pathogenesis of diseases linked to endothelial injury and inflammation in smokers. PMID:27530098

  5. Electrospray of multifunctional microparticles for image-guided drug delivery

    NASA Astrophysics Data System (ADS)

    Zhang, Leilei; Yan, Yan; Mena, Joshua; Sun, Jingjing; Letson, Alan; Roberts, Cynthia; Zhou, Chuanqing; Chai, Xinyu; Ren, Qiushi; Xu, Ronald

    2012-03-01

    Anti-VEGF therapies have been widely explored for the management of posterior ocular disease, like neovascular age-related macular degeneration (AMD). Loading anti-VEGF therapies in biodegradable microparticles may enable sustained drug release and improved therapeutic outcome. However, existing microfabrication processes such as double emulsification produce drug-loaded microparticles with low encapsulation rate and poor antibody bioactivity. To overcome these limitations, we fabricate multifunctional microparticles by both single needle and coaxial needle electrospray. The experimental setup for the process includes flat-end syringe needles (both single needle and coaxial needle), high voltage power supplies, and syringe pumps. Microparticles are formed by an electrical field between the needles and the ground electrode. Droplet size and morphology are controlled by multiple process parameters and material properties, such as flow rate and applied voltage. The droplets are collected and freezing dried to obtain multifunctional microparticles. Fluorescent beads encapsulated poly(DL-lactide-co-glycolide) acid (PLGA) microparticles are injected into rabbits eyes through intravitreal injection to test the biodegradable time of microparticles.

  6. Chitosan microparticles for sustaining the topical delivery of minoxidil sulphate.

    PubMed

    Gelfuso, Guilherme Martins; Gratieri, Taís; Simão, Patrícia Sper; de Freitas, Luís Alexandre Pedro; Lopez, Renata Fonseca Vianna

    2011-01-01

    Given the hypothesis that microparticles can penetrate the skin barrier along the transfollicular route, this work aimed to obtain and characterise chitosan microparticles loaded with minoxidil sulphate (MXS) and to study their ability to sustain the release of the drug, attempting a further application utilising them in a targeted delivery system for the topical treatment of alopecia. Chitosan microparticles, containing different proportions of MXS/polymer, were prepared by spray drying and were characterised by yield, encapsulation efficiency, size and morphology. Microparticles selected for further studies showed high encapsulation efficiency (∼82%), a mean diameter of 3.0 µm and a spherical morphology without porosities. When suspended in an ethanol/water solution, chitosan microparticles underwent instantaneous swelling, increasing their mean diameter by 90%. Release studies revealed that the chitosan microparticles were able to sustain about three times the release rate of MXS. This feature, combined with suitable size, confers to these microparticles the potential to target and improve topical therapy of alopecia with minoxidil. PMID:21824068

  7. In vivo biocompatibility of the PLGA microparticles in parotid gland

    PubMed Central

    Cantín, Mario; Miranda, Patricio; Suazo Galdames, Iván; Zavando, Daniela; Arenas, Patricia; Velásquez, Luis; Vilos, Cristian

    2013-01-01

    Poly(lactic-co-glycolic acid) (PLGA) microparticles are used in various disorders for the controlled or sustained release of drugs, with the management of salivary gland pathologies possible using this technology. There is no record of the response to such microparticles in the glandular parenchyma. The purpose of this study was to assess the morphological changes in the parotid gland when injected with a single dose of PLGA microparticles. We used 12 adult female Sprague Dawley rats (Rattus norvegicus) that were injected into their right parotid gland with sterile vehicle solution (G1, n=4), 0.5 mg PLGA microparticles (G2, n=4), and 0.75 mg PLGA microparticles (G3, n=4); the microparticles were dissolved in a sterile vehicle solution. The intercalar and striated ducts lumen, the thickness of the acini and the histology aspect in terms of the parenchyma organization, cell morphology of acini and duct system, the presence of polymeric residues, and inflammatory response were determined at 14 days post-injection. The administration of the compound in a single dose modified some of the morphometric parameters of parenchyma (intercalar duct lumen and thickness of the glandular acini) but did not induce tissue inflammatory response, despite the visible presence of polymer waste. This suggests that PLGA microparticles are biocompatible with the parotid tissue, making it possible to use intraglandular controlled drug administration. PMID:24228103

  8. Shock wave driven microparticles for pharmaceutical applications

    NASA Astrophysics Data System (ADS)

    Menezes, V.; Takayama, K.; Gojani, A.; Hosseini, S. H. R.

    2008-10-01

    Ablation created by a Q-switched Nd:Yttrium Aluminum Garnet (Nd:YAG) laser beam focusing on a thin aluminum foil surface spontaneously generates a shock wave that propagates through the foil and deforms it at a high speed. This high-speed foil deformation can project dry micro- particles deposited on the anterior surface of the foil at high speeds such that the particles have sufficient momentum to penetrate soft targets. We used this method of particle acceleration to develop a drug delivery device to deliver DNA/drug coated microparticles into soft human-body targets for pharmaceutical applications. The device physics has been studied by observing the process of particle acceleration using a high-speed video camera in a shadowgraph system. Though the initial rate of foil deformation is over 5 km/s, the observed particle velocities are in the range of 900-400 m/s over a distance of 1.5-10 mm from the launch pad. The device has been tested by delivering microparticles into liver tissues of experimental rats and artificial soft human-body targets, modeled using gelatin. The penetration depths observed in the experimental targets are quite encouraging to develop a future clinical therapeutic device for treatments such as gene therapy, treatment of cancer and tumor cells, epidermal and mucosal immunizations etc.

  9. Free surface electrospinning of fibers containing microparticles.

    PubMed

    Brettmann, Blair K; Tsang, Shirley; Forward, Keith M; Rutledge, Gregory C; Myerson, Allan S; Trout, Bernhardt L

    2012-06-26

    Many materials have been fabricated using electrospinning, including pharmaceutical formulations, superhydrophobic surfaces, catalysis supports, filters, and tissue engineering scaffolds. Often these materials can benefit from microparticles included within the electrospun fibers. In this work, we evaluate a high-throughput free surface electrospinning technique to prepare fibers containing microparticles. We investigate the spinnability of polyvinylpyrrolidone (PVP) solutions containing suspended polystyrene (PS) beads of 1, 3, 5, and 10 μm diameter in order to better understand free surface electrospinning of particle suspensions. PS bead suspensions with both 55 kDa PVP and 1.3 MDa PVP were spinnable at 1:10, 1:5, and 1:2 PS:PVP mass loadings for all particle sizes studied. The final average fiber diameters ranged from 0.47 to 1.2 μm and were independent of the particle size and particle loading, indicating that the fiber diameter can be smaller than the particles entrained and can furthermore be adjusted based on solution properties and electrospinning parameters, as is the case for electrospinning of solutions without particles.

  10. Microfluidics assisted generation of innovative polysaccharide hydrogel microparticles.

    PubMed

    Marquis, M; Davy, J; Cathala, B; Fang, A; Renard, D

    2015-02-13

    Capillary flow-based approach such as microfluidic devices offer a number of advantages over conventional flow control technology because they ensure highly versatile geometry and can be used to produce monodisperse spherical and non-spherical polymeric microparticles. Based on the principle of a flow-focusing device to emulsify the coflow of aqueous solutions in an organic phase, we were able to produce the following innovative polysaccharide hydrogel microparticles: - Janus hydrogel microparticles made of pectin–pectin (homo Janus) and pectin–alginate (hetero Janus) were produced. The efficiency of separation of the two hemispheres was investigated by confocal scanning laser microscopy (CSLM) of previously labelled biopolymers. The Janus structure was confirmed by subjecting each microparticle hemisphere to specific enzymatic degradation. As a proof of concept, free BSA or BSA grafted with dextran, were encapsulated in each hemisphere of the hetero Janus hydrogel microparticles. While BSA, free or grafted with dextran, was always confined in the alginate hemisphere, a fraction of BSA diffused from the pectin to the alginate hemisphere. Methoxy groups along the pectin chain will be responsible of the decrease of the number of attractive electrostatic interactions occurring between amino groups of BSA and carboxylic groups of pectin. - Pectin hydrogel microparticles of complex shapes were successfully produced by combining on-chip the phenomenon of gelation and water diffusion induced self-assembly, using dimethyl carbonate as continuous phase, or by deformation of the pre-gelled droplets off-chip at a fluid–fluid interface. Sphere, oblate ellipsoid, torus or mushroom-type morphologies were thus obtained. Moreover, it was established that after crossing the interface during their collect, mushroom-type microparticles did not migrate in the calcium or DMC phase but stayed at the liquid–liquid interface. These new and original hydrogel microparticles will

  11. Swellable Microparticles as Carriers for Sustained Pulmonary Drug Delivery

    PubMed Central

    EL-SHERBINY, IBRAHIM M.; MCGILL, SHAYNA; SMYTH, HUGH D.C.

    2012-01-01

    In this investigation, novel biodegradable physically crosslinked hydrogel micro-particles were developed and evaluated in vitro as potential carriers for sustained pulmonary drug delivery. To facilitate sustained release in the lungs, aerosols must first navigate past efficient aerodynamic filtering to penetrate to the deep lung (requires small particle size) where they must then avoid rapid macrophage clearance (enhanced by large particle size). The strategy suggested in this study to solve this problem is to deliver drug-loaded hydrogel microparticles with aerodynamic characteristics allowing them to be respirable when dry but attain large swollen sizes once deposited on moist lung surfaces to reduce macrophage uptake rates. The microparticles are based on PEG graft copolymerized onto chitosan in combination with Pluronic® F-108 and were prepared via cryomilling. The synthesized polymers used in preparation of the microparticles were characterized using FTIR, EA, 2D-XRD, and differential scanning calorimetry (DSC). The microparticles size, morphology, moisture content, and biodegradation rates were investigated. Swelling studies and in vitro drug release profiles were determined. An aerosolization study was conducted and macrophage uptake rates were evaluated against controls. The microparticles showed a respirable fraction of approximately 15% when prepared as dry powders. Enzymatic degradation of microparticles started within the first hour and about 7–41% weights were remaining after 240 h. Microparticles showed sustained release up to 10 and 20 days in the presence and absence of lysozyme, respectively. Preliminary macrophage interaction studies indicate that the developed hydrogel microparticles significantly delayed phagocytosis and may have the potential for sustained drug delivery to the lung. PMID:19967777

  12. Microfluidics assisted generation of innovative polysaccharide hydrogel microparticles.

    PubMed

    Marquis, M; Davy, J; Cathala, B; Fang, A; Renard, D

    2015-02-13

    Capillary flow-based approach such as microfluidic devices offer a number of advantages over conventional flow control technology because they ensure highly versatile geometry and can be used to produce monodisperse spherical and non-spherical polymeric microparticles. Based on the principle of a flow-focusing device to emulsify the coflow of aqueous solutions in an organic phase, we were able to produce the following innovative polysaccharide hydrogel microparticles: - Janus hydrogel microparticles made of pectin–pectin (homo Janus) and pectin–alginate (hetero Janus) were produced. The efficiency of separation of the two hemispheres was investigated by confocal scanning laser microscopy (CSLM) of previously labelled biopolymers. The Janus structure was confirmed by subjecting each microparticle hemisphere to specific enzymatic degradation. As a proof of concept, free BSA or BSA grafted with dextran, were encapsulated in each hemisphere of the hetero Janus hydrogel microparticles. While BSA, free or grafted with dextran, was always confined in the alginate hemisphere, a fraction of BSA diffused from the pectin to the alginate hemisphere. Methoxy groups along the pectin chain will be responsible of the decrease of the number of attractive electrostatic interactions occurring between amino groups of BSA and carboxylic groups of pectin. - Pectin hydrogel microparticles of complex shapes were successfully produced by combining on-chip the phenomenon of gelation and water diffusion induced self-assembly, using dimethyl carbonate as continuous phase, or by deformation of the pre-gelled droplets off-chip at a fluid–fluid interface. Sphere, oblate ellipsoid, torus or mushroom-type morphologies were thus obtained. Moreover, it was established that after crossing the interface during their collect, mushroom-type microparticles did not migrate in the calcium or DMC phase but stayed at the liquid–liquid interface. These new and original hydrogel microparticles will

  13. Multifunctional Hydrogel Microparticles by Polymer-Assisted Photolithography.

    PubMed

    Li, Bin; He, Muhan; Ramirez, Lisa; George, Justin; Wang, Jun

    2016-02-17

    Although standard lithography has been the most common technique in micropatterning, ironically it has not been adopted to produce multifunctional hydrogel microparticles, which are highly useful for bioassays. We address this issue by developing a negative photoresist-like polymer system, which is basically comprised of polyethylene glycol (PEG) triacrylate as cross-linking units and long-chain polyvinylpyrrolidone (PVP) as the supporting scaffold. We leverage standard lithography to manufacture multilayer microparticles that are intrinsically hydrophilic, low-autofluorescent, and chemically reactive. The versatility of the microparticles is demonstrated to be color-encoded, pore-controllable, bioactive, and potentially used as a DNA bioassay.

  14. Airborne Endotoxin from Indoor and Outdoor Environments:Effect of Sample Dilution on the Kinetic Limulus Amebocyte Lysate (LAL) Assay

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Airborne endotoxin in occupational environments are a potential respiratory hazard to individuals. In this study, total and inhalable airborne endotoxin samples were collected via filtration from inside animal housing units and downwind from agricultural production sites and a wastewater treatment ...

  15. Mars Airborne Prospecting Spectrometer

    NASA Astrophysics Data System (ADS)

    Steinkraus, J. M.; Wright, M. W.; Rheingans, B. E.; Steinkraus, D. E.; George, W. P.; Aljabri, A.; Hall, J. L.; Scott, D. C.

    2012-06-01

    One novel approach towards addressing the need for innovative instrumentation and investigation approaches is the integration of a suite of four spectrometer systems to form the Mars Airborne Prospecting Spectrometers (MAPS) for prospecting on Mars.

  16. Detection and Quantification of Microparticles from Different Cellular Lineages Using Flow Cytometry. Evaluation of the Impact of Secreted Phospholipase A2 on Microparticle Assessment

    PubMed Central

    Rousseau, Matthieu; Belleannee, Clemence; Duchez, Anne-Claire; Cloutier, Nathalie; Levesque, Tania; Jacques, Frederic; Perron, Jean; Nigrovic, Peter A.; Dieude, Melanie; Hebert, Marie-Josee; Gelb, Michael H.; Boilard, Eric

    2015-01-01

    Microparticles, also called microvesicles, are submicron extracellular vesicles produced by plasma membrane budding and shedding recognized as key actors in numerous physio(patho)logical processes. Since they can be released by virtually any cell lineages and are retrieved in biological fluids, microparticles appear as potent biomarkers. However, the small dimensions of microparticles and soluble factors present in body fluids can considerably impede their quantification. Here, flow cytometry with improved methodology for microparticle resolution was used to detect microparticles of human and mouse species generated from platelets, red blood cells, endothelial cells, apoptotic thymocytes and cells from the male reproductive tract. A family of soluble proteins, the secreted phospholipases A2 (sPLA2), comprises enzymes concomitantly expressed with microparticles in biological fluids and that catalyze the hydrolysis of membrane phospholipids. As sPLA2 can hydrolyze phosphatidylserine, a phospholipid frequently used to assess microparticles, and might even clear microparticles, we further considered the impact of relevant sPLA2 enzymes, sPLA2 group IIA, V and X, on microparticle quantification. We observed that if enriched in fluids, certain sPLA2 enzymes impair the quantification of microparticles depending on the species studied, the source of microparticles and the means of detection employed (surface phosphatidylserine or protein antigen detection). This study provides analytical considerations for appropriate interpretation of microparticle cytofluorometric measurements in biological samples containing sPLA2 enzymes. PMID:25587983

  17. Enhancement of laminar convective heat transfer using microparticle suspensions

    NASA Astrophysics Data System (ADS)

    Zhu, Jiu Yang; Tang, Shiyang; Yi, Pyshar; Baum, Thomas; Khoshmanesh, Khashayar; Ghorbani, Kamran

    2016-04-01

    This paper investigates the enhancement of convective heat transfer within a sub-millimetre diameter copper tube using Al2O3, Co3O4 and CuO microparticle suspensions. Experiments are conducted at different particle concentrations of 1.0, 2.0 and 5.0 wt% and at various flow rates ranging from 250 to 1000 µl/min. Both experimental measurements and numerical analyses are employed to obtain the convective heat transfer coefficient. The results indicate a significant enhancement in convective heat transfer coefficient due to the implementation of microparticle suspensions. For the case of Al2O3 microparticle suspension with 5.0 wt% concentration, a 20.3 % enhancement in convective heat transfer coefficient is obtained over deionised water. This is comparable to the case of Al2O3 nanofluid at the same concentration. Hence, there is a potential for the microparticle suspensions to be used for cooling of compact integrated systems.

  18. Numerical Simulations of the Digital Microfluidic Manipulation of Single Microparticles.

    PubMed

    Lan, Chuanjin; Pal, Souvik; Li, Zhen; Ma, Yanbao

    2015-09-01

    Single-cell analysis techniques have been developed as a valuable bioanalytical tool for elucidating cellular heterogeneity at genomic, proteomic, and cellular levels. Cell manipulation is an indispensable process for single-cell analysis. Digital microfluidics (DMF) is an important platform for conducting cell manipulation and single-cell analysis in a high-throughput fashion. However, the manipulation of single cells in DMF has not been quantitatively studied so far. In this article, we investigate the interaction of a single microparticle with a liquid droplet on a flat substrate using numerical simulations. The droplet is driven by capillary force generated from the wettability gradient of the substrate. Considering the Brownian motion of microparticles, we utilize many-body dissipative particle dynamics (MDPD), an off-lattice mesoscopic simulation technique, in this numerical study. The manipulation processes (including pickup, transport, and drop-off) of a single microparticle with a liquid droplet are simulated. Parametric studies are conducted to investigate the effects on the manipulation processes from the droplet size, wettability gradient, wetting properties of the microparticle, and particle-substrate friction coefficients. The numerical results show that the pickup, transport, and drop-off processes can be precisely controlled by these parameters. On the basis of the numerical results, a trap-free delivery of a hydrophobic microparticle to a destination on the substrate is demonstrated in the numerical simulations. The numerical results not only provide a fundamental understanding of interactions among the microparticle, the droplet, and the substrate but also demonstrate a new technique for the trap-free immobilization of single hydrophobic microparticles in the DMF design. Finally, our numerical method also provides a powerful design and optimization tool for the manipulation of microparticles in DMF systems.

  19. Numerical Simulations of the Digital Microfluidic Manipulation of Single Microparticles.

    PubMed

    Lan, Chuanjin; Pal, Souvik; Li, Zhen; Ma, Yanbao

    2015-09-01

    Single-cell analysis techniques have been developed as a valuable bioanalytical tool for elucidating cellular heterogeneity at genomic, proteomic, and cellular levels. Cell manipulation is an indispensable process for single-cell analysis. Digital microfluidics (DMF) is an important platform for conducting cell manipulation and single-cell analysis in a high-throughput fashion. However, the manipulation of single cells in DMF has not been quantitatively studied so far. In this article, we investigate the interaction of a single microparticle with a liquid droplet on a flat substrate using numerical simulations. The droplet is driven by capillary force generated from the wettability gradient of the substrate. Considering the Brownian motion of microparticles, we utilize many-body dissipative particle dynamics (MDPD), an off-lattice mesoscopic simulation technique, in this numerical study. The manipulation processes (including pickup, transport, and drop-off) of a single microparticle with a liquid droplet are simulated. Parametric studies are conducted to investigate the effects on the manipulation processes from the droplet size, wettability gradient, wetting properties of the microparticle, and particle-substrate friction coefficients. The numerical results show that the pickup, transport, and drop-off processes can be precisely controlled by these parameters. On the basis of the numerical results, a trap-free delivery of a hydrophobic microparticle to a destination on the substrate is demonstrated in the numerical simulations. The numerical results not only provide a fundamental understanding of interactions among the microparticle, the droplet, and the substrate but also demonstrate a new technique for the trap-free immobilization of single hydrophobic microparticles in the DMF design. Finally, our numerical method also provides a powerful design and optimization tool for the manipulation of microparticles in DMF systems. PMID:26241832

  20. Nitric Oxide Regulates Neutrophil Migration through Microparticle Formation

    PubMed Central

    Nolan, Sarah; Dixon, Rachel; Norman, Keith; Hellewell, Paul; Ridger, Victoria

    2008-01-01

    The role of nitric oxide (NO) in regulating neutrophil migration has been investigated. Human neutrophil migration to interleukin (IL)-8 (1 nmol/L) was measured after a 1-hour incubation using a 96-well chemotaxis plate assay. The NO synthase inhibitor NG-nitro-l-arginine methyl ester (L-NAME) significantly (P < 0.001) enhanced IL-8-induced migration by up to 45%. Anti-CD18 significantly (P < 0.001) inhibited both IL-8-induced and L-NAME enhanced migration. Antibodies to L-selectin or PSGL-1 had no effect on IL-8-induced migration but prevented the increased migration to IL-8 induced by L-NAME. L-NAME induced generation of neutrophil-derived microparticles that was significantly (P < 0.01) greater than untreated neutrophils or D-NAME. This microparticle formation was dependent on calpain activity and superoxide production. Only microparticles from L-NAME and not untreated or D-NAME-treated neutrophils induced a significant (P < 0.01) increase in IL-8-induced migration and transendothelial migration. Pretreatment of microparticles with antibodies to L-selectin (DREG-200) or PSGL-1 (PL-1) significantly (P < 0.001) inhibited this effect. The ability of L-NAME-induced microparticles to enhance migration was found to be dependent on the number of microparticles produced and not an increase in microparticle surface L-selectin or PSGL-1 expression. These data show that NO can modulate neutrophil migration by regulating microparticle formation. PMID:18079439

  1. Innovation in detection of microparticles and exosomes.

    PubMed

    van der Pol, E; Coumans, F; Varga, Z; Krumrey, M; Nieuwland, R

    2013-06-01

    Cell-derived or extracellular vesicles, including microparticles and exosomes, are abundantly present in body fluids such as blood. Although such vesicles have gained strong clinical and scientific interest, their detection is difficult because many vesicles are extremely small with a diameter of less than 100 nm, and, moreover, these vesicles have a low refractive index and are heterogeneous in both size and composition. In this review, we focus on the relatively high throughput detection of vesicles in suspension by flow cytometry, resistive pulse sensing, and nanoparticle tracking analysis, and we will discuss their applicability and limitations. Finally, we discuss four methods that are not commercially available: Raman microspectroscopy, micro nuclear magnetic resonance, small-angle X-ray scattering (SAXS), and anomalous SAXS. These methods are currently being explored to study vesicles and are likely to offer novel information for future developments. PMID:23809109

  2. Microparticle assembly and contact line dynamics

    NASA Astrophysics Data System (ADS)

    Ghosh, Moniraj

    This thesis addresses three topics. First, microparticle assembly on solid surfaces from an evaporative suspension is studied. It is well known that microparticles collect near three phase contact lines owing to evaporative fluxes. In a dip coating configuration, if the evaporative flux and plate withdrawal velocity U are matched, large colloidal crystals form. Here, I investigate the consequences of varying the plate withdrawal rate, and find that periodic striped patterns emerge which depend strongly on U. The stripes form when three phase contact lines "jump", or recede rapidly, upon detaching from well-wet particle aggregates on less wet substrates. Stripe width, spacing and height change abruptly at a transition velocity which can be related to a Landau-Levich transition in the flow. The second part of my thesis is a numerical simulation of drop spreading and retraction as a function of drop scale. The drop moves over a thin liquid film, and drop motion is initiated by an impulsive change in surface wettability. Owing to the presence of the film, these simulations require no closure condition at the 'apparent' contact line. Rather, relationships emerge between the contact line velocity and the dynamic contact angle. For nanoscopic drops, molecular effects dominate the drop motion. For drops an order of magnitude larger than the thin film, regimes emerge in which drops move according to Tanner's law, a relationship derived for macroscopic drops. Drop retraction is considerably more rapid than spreading owing to rapid dewetting events near the contact line. This thesis concludes with a discussion of a technique for creating multifunctional surfaces presenting discrete patches of several proteins. The technique relies on microcontact printing (microCP) to define active regions, and the use of a microfluidics device to deliver proteins to those regions. The surfaces are used to capture cells from a suspension, to sort cells from a mixed suspension, and to study

  3. [Biodegradable microparticles with immobilized peptide for wound healing].

    PubMed

    Stashevskaia, K S; Markvicheva, E A; Strukova, S M; Rusanova, A V; Makarova, A M; Gorbacheva, L R; Prudchenko, I A; Zubov, V P; Grandfis, K

    2006-01-01

    Thrombin receptor agonist peptide (TRAP-6) may effectively replace thrombin for stimulation of damaged tissue regeneration. (Thrombin employment is limited by its high cost, instability and proinflammatory effect at high concentrations.) Immobilization of TRAP-6 into a poly(D,L)-lactide-co-glycolide (PLGA)-based matrix can protect peptides from a destruction by peptidases located in a wound area, and can also provide controlled release of the peptide. PLGA microparticles with immobilized peptide were produced by double emulsion/evaporation technique. An observation of microparticle morphology by scanning electron microscopy highlighted that peptide immobilization resulted in the increase of the microparticle porosity. TRAP-6 release kinetics was characterized by burst increase of TRAP-6 concentration in HEPES buffer solution (pH 7.5) for first 2 hours from the beginning of the experiment, and TRAP-6 complete release occurred for 20 hours. An investigation of TRAP-6 destruction by scanning electron microscopy revealed that the increase of microparticle size and surface porosity were observed already after 1 day of incubation in the buffer solution, and an aggregation of destructing microparticles was obvious by the 7th day of the incubation. Thus, peptide immobilization into PLGA microparticles can allow to develop a novel controlled release drug delivery system. PMID:16739924

  4. Risedronate-loaded Eudragit S100 microparticles formulated into tablets.

    PubMed

    Velasquez, Aline A; Mattiazzi, Juliane; Ferreira, Luana M; Pohlmann, Lauren; Silva, Cristiane B; Rolim, Clarice M B; Cruz, Letícia

    2014-05-01

    Risedronate, an anti-osteoporotic drug, is associated with low patient compliance due to the upper gastrointestinal side-effects and stringent dosing regimes. This study aimed to prepare and characterize risedronate-loaded Eudragit® S100 microparticles and develop a final dosage form by the compression of microparticles using direct tableting excipients. Microparticles were prepared by spray-drying and presented yield of 54%, encapsulation efficiency higher than 90%, mean diameter of 3.3 µm, moisture content around 8% and exhibited spherical shape and poor flowability. At pH 1.2, 23% of risedronate was released from microparticles in 120 min, while at pH 6.8 the drug took 90 min to reach 99.5%. Microparticles were compressed into tablets using microcrystalline cellulose, magnesium stearate, colloidal silicon dioxide and 2 polyvinylpyrrolidone concentrations (5% and 15%). Tablets presented low variations in weight, thickness and drug content. Besides, the formulations showed sufficient hardness, low friability and disintegrated in less than 15 min. In acid medium, no more than 16% of the drug was released in 120 min, while in intestinal medium the formulations prolonged the risedronate release for 240 min. Finally, the developed tableted microparticles can be considered a promising dosage form for oral risedronate administration. PMID:23506303

  5. Overcoming limitations of microparticle measurement by flow cytometry.

    PubMed

    Lacroix, Romaric; Robert, Stephane; Poncelet, Philippe; Dignat-George, Françoise

    2010-11-01

    Circulating microparticles are submicron vesicles released from cell membranes in response to activation or apoptosis. Acknowledgment of their role both as markers and pathogenic effectors in thrombosis, inflammation, and the spread of cancer has increased the interest of their measurement in clinical practice. However, assessment of their clinical use is impeded by technological issues. Among the different methodologies available, flow cytometry is the most commonly used technique. This review addresses flow cytometry limitations in microparticle measurement that may be subdivided into three domains: sizing, probing, and counting. This article also covers the various standardization strategies and technological improvements that have been proposed to overcome these limitations. New tools using size-calibrated beads and recent progress in instrumentation have opened new avenues to improve detection of microparticle populations of smaller sizes. Significant optimization in microparticle detection is also expected from the use of new fluorescent dyes and the establishment of practical recommendations. Finally, absolute counting of microparticles will also benefit from adapted bead-based strategies or, alternatively, from the generalized availability of volumetric systems. Overall, recent technological improvements maintain flow cytometry as a highly competitive analytical method to measure microparticles. Challenging these evolutions in pathological situations is a mandatory step to validate their real impact in clinical practice.

  6. Detection and Monitoring of Microparticles Under Skin by Optical Coherence Tomography as an Approach to Continuous Glucose Sensing Using Implanted Retroreflectors

    PubMed Central

    Wang, Shang; Sherlock, Tim; Salazar, Betsy; Sudheendran, Narendran; Manapuram, Ravi Kiran; Kourentzi, Katerina; Ruchhoeft, Paul; Willson, Richard C.; Larin, Kirill V.

    2015-01-01

    We demonstrate the feasibility of using optical coherence tomography (OCT) to image and detect 2.8 μm diameter microparticles (stationary and moving) on a highly-reflective gold surface both in clear media and under skin in vitro. The OCT intensity signal can clearly report the microparticle count, and the OCT response to the number of microparticles shows a good linearity. The detect ability of the intensity change (2.9% ± 0.5%) caused by an individual microparticle shows the high sensitivity of monitoring multiple particles using OCT. An optical sensing method based on this feasibility study is described for continuously measuring blood sugar levels in the subcutaneous tissue, and a molecular recognition unit is designed using competitive binding to modulate the number of bound microparticles as a function of glucose concentration. With further development, an ultra-small, implantable sensor might provide high specificity and sensitivity for long-term continuous monitoring of blood glucose concentration. PMID:26413034

  7. Cryogenic transmission electron microscopy nanostructural study of shed microparticles.

    PubMed

    Issman, Liron; Brenner, Benjamin; Talmon, Yeshayahu; Aharon, Anat

    2013-01-01

    Microparticles (MPs) are sub-micron membrane vesicles (100-1000 nm) shed from normal and pathologic cells due to stimulation or apoptosis. MPs can be found in the peripheral blood circulation of healthy individuals, whereas elevated concentrations are found in pregnancy and in a variety of diseases. Also, MPs participate in physiological processes, e.g., coagulation, inflammation, and angiogenesis. Since their clinical properties are important, we have developed a new methodology based on nano-imaging that provides significant new data on MPs nanostructure, their composition and function. We are among the first to characterize by direct-imaging cryogenic transmitting electron microscopy (cryo-TEM) the near-to-native nanostructure of MP systems isolated from different cell types and stimulation procedures. We found that there are no major differences between the MP systems we have studied, as most particles were spherical, with diameters from 200 to 400 nm. However, each MP population is very heterogeneous, showing diverse morphologies. We investigated by cryo-TEM the effects of standard techniques used to isolate and store MPs, and found that either high-g centrifugation of MPs for isolation purposes, or slow freezing to -80 °C for storage introduce morphological artifacts, which can influence MP nanostructure, and thus affect the efficiency of these particles as future diagnostic tools.

  8. Airborne data acquisition techniques

    SciTech Connect

    Arro, A.A.

    1980-01-01

    The introduction of standards on acceptable procedures for assessing building heat loss has created a dilemma for the contractor performing airborne thermographic surveys. These standards impose specifications on instrumentation, data acquisition, recording, interpretation, and presentation. Under the standard, the contractor has both the obligation of compliance and the requirement of offering his services at a reasonable price. This paper discusses the various aspects of data acquisition for airborne thermographic surveys and various techniques to reduce the costs of this operation. These techniques include the calculation of flight parameters for economical data acquisition, the selection and use of maps for mission planning, and the use of meteorological forecasts for flight scheduling and the actual execution of the mission. The proper consideration of these factors will result in a cost effective data acquisition and will place the contractor in a very competitive position in offering airborne thermographic survey services.

  9. Disintegration of nano-embedded microparticles after deposition on mucus: A mechanistic study.

    PubMed

    Ruge, Christian A; Bohr, Adam; Beck-Broichsitter, Moritz; Nicolas, Valérie; Tsapis, Nicolas; Fattal, Elias

    2016-03-01

    The conversion of colloidal drug carriers/polymeric nanoparticles into dry microparticulate powders (e.g., by spray-drying) is a prominent approach to overcome the aerodynamic limitations of these formulations for delivery via inhalation. However, to what extent such nano-embedded microparticles disintegrate into individual/intact nanoparticles after contacting relevant physiological media has so far not been addressed. Polymeric nanoparticles were spray-dried into nano-embedded microparticles (NEMs) using different amounts of trehalose as embedding matrix excipient. Formulations were characterized and then evaluated for their disintegration behavior after aerosolization onto model mucus. Although a rapid and complete aqueous redispersion was observed for specific excipient/nanoparticle weight ratios (i.e., greater than 1/1), the same formulations revealed no disintegration after deposition onto a static mucus layer. Double-labeled NEMs powders (i.e., dual color staining of polymeric nanoparticles and trehalose) demonstrated rapid matrix dissolution, while the nanoparticle aggregates persisted. When deposited onto agitated mucus, however, sufficient disintegration of NEMs into individual polymeric nanoparticles was observed. These findings indicate that mechanical forces are necessary to overcome the attraction between individual nanoparticles found within the NEMs. Thus, it remains questionable whether the lung mechanics (e.g., breathing, mucociliary clearance) acting on these formulations will contribute to the overall disintegration process.

  10. Airborne oceanographic lidar system

    NASA Technical Reports Server (NTRS)

    1975-01-01

    Specifications and preliminary design of an Airborne Oceanographic Lidar (AOL) system, which is to be constructed for installation and used on a NASA Wallops Flight Center (WFC) C-54 research aircraft, are reported. The AOL system is to provide an airborne facility for use by various government agencies to demonstrate the utility and practicality of hardware of this type in the wide area collection of oceanographic data on an operational basis. System measurement and performance requirements are presented, followed by a description of the conceptual system approach and the considerations attendant to its development. System performance calculations are addressed, and the system specifications and preliminary design are presented and discussed.

  11. Airborne rain mapping radar

    NASA Technical Reports Server (NTRS)

    Wilson, W. J.; Parks, G. S.; Li, F. K.; Im, K. E.; Howard, R. J.

    1988-01-01

    An airborne scanning radar system for remote rain mapping is described. The airborne rain mapping radar is composed of two radar frequency channels at 13.8 and 24.1 GHz. The radar is proposed to scan its antenna beam over + or - 20 deg from the antenna boresight; have a swath width of 7 km; a horizontal spatial resolution at nadir of about 500 m; and a range resolution of 120 m. The radar is designed to be applicable for retrieving rainfall rates from 0.1-60 mm/hr at the earth's surface, and for measuring linear polarization signatures and raindrop's fall velocity.

  12. Urban greenness influences airborne bacterial community composition.

    PubMed

    Mhuireach, Gwynne; Johnson, Bart R; Altrichter, Adam E; Ladau, Joshua; Meadow, James F; Pollard, Katherine S; Green, Jessica L

    2016-11-15

    Urban green space provides health benefits for city dwellers, and new evidence suggests that microorganisms associated with soil and vegetation could play a role. While airborne microorganisms are ubiquitous in urban areas, the influence of nearby vegetation on airborne microbial communities remains poorly understood. We examined airborne microbial communities in parks and parking lots in Eugene, Oregon, using high-throughput sequencing of the bacterial 16S rRNA gene on the Illumina MiSeq platform to identify bacterial taxa, and GIS to measure vegetation cover in buffer zones of different diameters. Our goal was to explore variation among highly vegetated (parks) versus non-vegetated (parking lots) urban environments. A secondary objective was to evaluate passive versus active collection methods for outdoor airborne microbial sampling. Airborne bacterial communities from five parks were different from those of five parking lots (p=0.023), although alpha diversity was similar. Direct gradient analysis showed that the proportion of vegetated area within a 50m radius of the sampling station explained 15% of the variation in bacterial community composition. A number of key taxa, including several Acidobacteriaceae were substantially more abundant in parks, while parking lots had higher relative abundance of Acetobacteraceae. Parks had greater beta diversity than parking lots, i.e. individual parks were characterized by unique bacterial signatures, whereas parking lot communities tended to be similar to each other. Although parks and parking lots were selected to form pairs of nearby sites, spatial proximity did not appear to affect compositional similarity. Our results also showed that passive and active collection methods gave comparable results, indicating the "settling dish" method is effective for outdoor airborne sampling. This work sets a foundation for understanding how urban vegetation may impact microbial communities, with potential implications for designing

  13. Urban greenness influences airborne bacterial community composition.

    PubMed

    Mhuireach, Gwynne; Johnson, Bart R; Altrichter, Adam E; Ladau, Joshua; Meadow, James F; Pollard, Katherine S; Green, Jessica L

    2016-11-15

    Urban green space provides health benefits for city dwellers, and new evidence suggests that microorganisms associated with soil and vegetation could play a role. While airborne microorganisms are ubiquitous in urban areas, the influence of nearby vegetation on airborne microbial communities remains poorly understood. We examined airborne microbial communities in parks and parking lots in Eugene, Oregon, using high-throughput sequencing of the bacterial 16S rRNA gene on the Illumina MiSeq platform to identify bacterial taxa, and GIS to measure vegetation cover in buffer zones of different diameters. Our goal was to explore variation among highly vegetated (parks) versus non-vegetated (parking lots) urban environments. A secondary objective was to evaluate passive versus active collection methods for outdoor airborne microbial sampling. Airborne bacterial communities from five parks were different from those of five parking lots (p=0.023), although alpha diversity was similar. Direct gradient analysis showed that the proportion of vegetated area within a 50m radius of the sampling station explained 15% of the variation in bacterial community composition. A number of key taxa, including several Acidobacteriaceae were substantially more abundant in parks, while parking lots had higher relative abundance of Acetobacteraceae. Parks had greater beta diversity than parking lots, i.e. individual parks were characterized by unique bacterial signatures, whereas parking lot communities tended to be similar to each other. Although parks and parking lots were selected to form pairs of nearby sites, spatial proximity did not appear to affect compositional similarity. Our results also showed that passive and active collection methods gave comparable results, indicating the "settling dish" method is effective for outdoor airborne sampling. This work sets a foundation for understanding how urban vegetation may impact microbial communities, with potential implications for designing

  14. NASA Airborne Lidar July 1991

    Atmospheric Science Data Center

    2016-05-26

    NASA Airborne Lidar July 1991 Data from the 1991 NASA Langley Airborne Lidar flights following the eruption of Pinatubo in July ... and Osborn [1992a, 1992b]. Project Title:  NASA Airborne Lidar Discipline:  Field Campaigns ...

  15. NASA Airborne Lidar May 1992

    Atmospheric Science Data Center

    2016-05-26

    NASA Airborne Lidar May 1992 An airborne Nd:YAG (532 nm) lidar was operated by the NASA Langley Research Center about a year following the June 1991 eruption of ... Osborn [1992a, 1992b].  Project Title:  NASA Airborne Lidar Discipline:  Field Campaigns ...

  16. Airborne Fraunhofer Line Discriminator

    NASA Technical Reports Server (NTRS)

    Gabriel, F. C.; Markle, D. A.

    1969-01-01

    Airborne Fraunhofer Line Discriminator enables prospecting for fluorescent materials, hydrography with fluorescent dyes, and plant studies based on fluorescence of chlorophyll. Optical unit design is the coincidence of Fraunhofer lines in the solar spectrum occurring at the characteristic wavelengths of some fluorescent materials.

  17. Recognizing Airborne Hazards.

    ERIC Educational Resources Information Center

    Schneider, Christian M.

    1990-01-01

    The heating, ventilating, and air conditioning (HVAC) systems in older buildings often do not adequately handle air-borne contaminants. Outlines a three-stage Indoor Air Quality (IAQ) assessment and describes a case in point at a Pittsburgh, Pennsylvania, school. (MLF)

  18. Airborne asbestos in buildings.

    PubMed

    Lee, R J; Van Orden, D R

    2008-03-01

    The concentration of airborne asbestos in buildings nationwide is reported in this study. A total of 3978 indoor samples from 752 buildings, representing nearly 32 man-years of sampling, have been analyzed by transmission electron microscopy. The buildings that were surveyed were the subject of litigation related to suits alleging the general building occupants were exposed to a potential health hazard as a result the presence of asbestos-containing materials (ACM). The average concentration of all airborne asbestos structures was 0.01structures/ml (s/ml) and the average concentration of airborne asbestos > or = 5microm long was 0.00012fibers/ml (f/ml). For all samples, 99.9% of the samples were <0.01 f/ml for fibers longer than 5microm; no building averaged above 0.004f/ml for fibers longer than 5microm. No asbestos was detected in 27% of the buildings and in 90% of the buildings no asbestos was detected that would have been seen optically (> or = 5microm long and > or = 0.25microm wide). Background outdoor concentrations have been reported at 0.0003f/ml > or = 5microm. These results indicate that in-place ACM does not result in elevated airborne asbestos in building atmospheres approaching regulatory levels and that it does not result in a significantly increased risk to building occupants.

  19. Amorphous Calcium Carbonate Based-Microparticles for Peptide Pulmonary Delivery.

    PubMed

    Tewes, Frederic; Gobbo, Oliviero L; Ehrhardt, Carsten; Healy, Anne Marie

    2016-01-20

    Amorphous calcium carbonate (ACC) is known to interact with proteins, for example, in biogenic ACC, to form stable amorphous phases. The control of amorphous/crystalline and inorganic/organic ratios in inhalable calcium carbonate microparticles may enable particle properties to be adapted to suit the requirements of dry powders for pulmonary delivery by oral inhalation. For example, an amorphous phase can immobilize and stabilize polypeptides in their native structure and amorphous and crystalline phases have different mechanical properties. Therefore, inhalable composite microparticles made of inorganic (i.e., calcium carbonate and calcium formate) and organic (i.e., hyaluronan (HA)) amorphous and crystalline phases were investigated for peptide and protein pulmonary aerosol delivery. The crystalline/amorphous ratio and polymorphic form of the inorganic component was altered by changing the microparticle drying rate and by changing the ammonium carbonate and HA initial concentration. The bioactivity of the model peptide, salmon calcitonin (sCT), coprocessed with alpha-1-antitrypsin (AAT), a model protein with peptidase inhibitor activity, was maintained during processing and the microparticles had excellent aerodynamic properties, making them suitable for pulmonary aerosol delivery. The bioavailability of sCT after aerosol delivery as sCT and AAT-loaded composite microparticles to rats was 4-times higher than that of sCT solution.

  20. Microparticles from apoptotic platelets promote resident macrophage differentiation

    PubMed Central

    Vasina, E M; Cauwenberghs, S; Feijge, M A H; Heemskerk, J W M; Weber, C; Koenen, R R

    2011-01-01

    Platelets shed microparticles not only upon activation, but also upon ageing by an apoptosis-like process (apoptosis-induced platelet microparticles, PMap). While the activation-induced microparticles have widely been studied, not much is known about the (patho)physiological consequences of PMap formation. Flow cytometry and scanning electron microscopy demonstrated that PMap display activated integrins and interact to form microparticle aggregates. PMap were chemotactic for monocytic cells, bound to these cells, an furthermore stimulated cell adhesion and spreading on a fibronectin surface. After prolonged incubation, PMap promoted cell differentiation, but inhibited proliferation. Monocyte membrane receptor analysis revealed increased expression levels of CD11b (integrin αMβ2), CD14 and CD31 (platelet endothelial cell adhesion molecule-1), and the chemokine receptors CCR5 and CXCR4, but not of CCR2. This indicated that PMap polarized the cells into resident M2 monocytes. Cells treated with PMap actively consumed oxidized low-density lipoprotein (oxLDL), and released matrix metalloproteinases and hydrogen peroxide. Further confirmation for the differentiation towards resident professional phagocytes came from the finding that PMap stimulated the expression of the (ox)LDL receptors, CD36 and CD68, and the production of proinflammatory and immunomodulating cytokines by monocytes. In conclusion, interaction of PMap with monocytic cells has an immunomodulating potential. The apoptotic microparticles polarize the cells into a resident M2 subset, and induce differentiation to resident professional phagocytes. PMID:21956548

  1. Titanium Dioxide Nanofibers and Microparticles Containing Nickel Nanoparticles

    PubMed Central

    Sheikh, Faheem A.; Macossay, Javier; Kanjwal, Muzafar A.; Abdal-hay, Abdalla; Tantry, Mudasir A.; Kim, Hern

    2013-01-01

    The present study reports on the introduction of various nanocatalysts containing nickel (Ni) nanoparticles (NPs) embedded within TiO2 nanofibers and TiO2 microparticles. Typically, a sol-gel consisting of titanium isopropoxide and Ni NPs was prepared to produce TiO2 nanofibers by the electrospinning process. Similarly, TiO2 microparticles containing Ni were prepared using a sol-gel syntheses process. The resultant structures were studied by SEM analyses, which confirmed well-obtained nanofibers and microparticles. Further, the XRD results demonstrated the crystalline feature of both TiO2 and Ni in the obtained composites. Internal morphology of prepared nanofibers and microparticles containing Ni NPs was characterized by TEM, which demonstrated characteristic structures with good dispersion of Ni NPs. In addition, the prepared structures were studied as a model for hydrogen production applications. The catalytic activity of the prepared materials was studied by in situ hydrolysis of NaBH4, which indicated that the nanofibers containing Ni NPs can lead to produce higher amounts of hydrogen when compared to other microparticles, also reported in this paper. Overall, these results confirm the potential use of these materials in hydrogen production systems. PMID:24436780

  2. Aqueous Two Phase System Assisted Self-Assembled PLGA Microparticles

    NASA Astrophysics Data System (ADS)

    Yeredla, Nitish; Kojima, Taisuke; Yang, Yi; Takayama, Shuichi; Kanapathipillai, Mathumai

    2016-06-01

    Here, we produce poly(lactide-co-glycolide) (PLGA) based microparticles with varying morphologies, and temperature responsive properties utilizing a Pluronic F127/dextran aqueous two-phase system (ATPS) assisted self-assembly. The PLGA polymer, when emulsified in Pluronic F127/dextran ATPS, forms unique microparticle structures due to ATPS guided-self assembly. Depending on the PLGA concentration, the particles either formed a core-shell or a composite microparticle structure. The microparticles facilitate the simultaneous incorporation of both hydrophobic and hydrophilic molecules, due to their amphiphilic macromolecule composition. Further, due to the lower critical solution temperature (LCST) properties of Pluronic F127, the particles exhibit temperature responsiveness. The ATPS based microparticle formation demonstrated in this study, serves as a novel platform for PLGA/polymer based tunable micro/nano particle and polymersome development. The unique properties may be useful in applications such as theranostics, synthesis of complex structure particles, bioreaction/mineralization at the two-phase interface, and bioseparations.

  3. Aqueous Two Phase System Assisted Self-Assembled PLGA Microparticles

    PubMed Central

    Yeredla, Nitish; Kojima, Taisuke; Yang, Yi; Takayama, Shuichi; Kanapathipillai, Mathumai

    2016-01-01

    Here, we produce poly(lactide-co-glycolide) (PLGA) based microparticles with varying morphologies, and temperature responsive properties utilizing a Pluronic F127/dextran aqueous two-phase system (ATPS) assisted self-assembly. The PLGA polymer, when emulsified in Pluronic F127/dextran ATPS, forms unique microparticle structures due to ATPS guided-self assembly. Depending on the PLGA concentration, the particles either formed a core-shell or a composite microparticle structure. The microparticles facilitate the simultaneous incorporation of both hydrophobic and hydrophilic molecules, due to their amphiphilic macromolecule composition. Further, due to the lower critical solution temperature (LCST) properties of Pluronic F127, the particles exhibit temperature responsiveness. The ATPS based microparticle formation demonstrated in this study, serves as a novel platform for PLGA/polymer based tunable micro/nano particle and polymersome development. The unique properties may be useful in applications such as theranostics, synthesis of complex structure particles, bioreaction/mineralization at the two-phase interface, and bioseparations. PMID:27279329

  4. Moxifloxacin in situ gelling microparticles-bioadhesive delivery system.

    PubMed

    Guo, Qiongyu; Aly, Ahmed; Schein, Oliver; Trexler, Morgana M; Elisseeff, Jennifer H

    2012-01-01

    Antibiotic use for ocular treatments has been largely limited by poor local bioavailability with conventional eyedrops formulations. Here, we developed a controlled delivery system composed of moxifloxacin-loaded poly(lactic-co-glycolic acid) (PLGA) microparticles encapsulated in a chondroitin sulfate-based, two-component bioadhesive hydrogel. Using a simple and fast electrohydrodynamic spray drying (electrospraying) technique, surfactant-free moxifloxacin-loaded microparticles were fabricated with diameters on the order of 1 μm. A mixed solvent system of methanol/dichloromethane (MeOH/DCM) was employed to prepare the microparticles for the electrospraying processing. Extended release of moxifloxacin using a series of MeOH/DCM mixed solvents was accomplished over 10 days with release concentrations higher than the minimum inhibitory concentration (MIC). In contrast, moxifloxacin loaded directly in hydrogels was released rapidly within 24 h. We observed a decrease of the drug release rate from the microparticles when using an increased percentage of methanol in the mixed solvent from 10% to 30% (v/v), which can be explained by the mixed solvent system providing a driving force to form a gradient of the drug concentrations inside the microparticles. In addition, the delivery system developed in this study, which incorporates a bioadhesive to localize drug release by in situ gelling, may potentially integrate antibiotic prophylaxis and wound healing in the eye. PMID:25755996

  5. An experimental study of microneedle-assisted microparticle delivery.

    PubMed

    Zhang, Dongwei; Das, Diganta B; Rielly, Chris D

    2013-10-01

    A set of well-defined experiments has been carried out to explore whether microneedles (MNs) can enhance the penetration depths of microparticles moving at high velocity such as those expected in gene guns for delivery of gene-loaded microparticles into target tissues. These experiments are based on applying solid MNs that are used to reduce the effect of mechanical barrier function of the target so as to allow delivery of microparticles at less imposed pressure as compared with most typical gene guns. Further, a low-cost material, namely, biomedical-grade stainless steel microparticle with size ranging between 1 and 20 μm, has been used in this study. The microparticles are compressed and bound in the form of a cylindrical pellet and mounted on a ground slide, which are then accelerated together by compressed air through a barrel. When the ground slide reaches the end of the barrel, the pellet is separated from the ground slide and is broken down into particle form by a mesh that is placed at the end of the barrel. Subsequently, these particles penetrate into the target. This paper investigates the implications of velocity of the pellet along with various other important factors that affect the particle delivery into the target. Our results suggest that the particle passage increases with an increase in pressure, mesh pore size, and decreases with increase in polyvinylpyrrolidone concentration. Most importantly, it is shown that MNs increase the penetration depths of the particles.

  6. Amorphous Calcium Carbonate Based-Microparticles for Peptide Pulmonary Delivery.

    PubMed

    Tewes, Frederic; Gobbo, Oliviero L; Ehrhardt, Carsten; Healy, Anne Marie

    2016-01-20

    Amorphous calcium carbonate (ACC) is known to interact with proteins, for example, in biogenic ACC, to form stable amorphous phases. The control of amorphous/crystalline and inorganic/organic ratios in inhalable calcium carbonate microparticles may enable particle properties to be adapted to suit the requirements of dry powders for pulmonary delivery by oral inhalation. For example, an amorphous phase can immobilize and stabilize polypeptides in their native structure and amorphous and crystalline phases have different mechanical properties. Therefore, inhalable composite microparticles made of inorganic (i.e., calcium carbonate and calcium formate) and organic (i.e., hyaluronan (HA)) amorphous and crystalline phases were investigated for peptide and protein pulmonary aerosol delivery. The crystalline/amorphous ratio and polymorphic form of the inorganic component was altered by changing the microparticle drying rate and by changing the ammonium carbonate and HA initial concentration. The bioactivity of the model peptide, salmon calcitonin (sCT), coprocessed with alpha-1-antitrypsin (AAT), a model protein with peptidase inhibitor activity, was maintained during processing and the microparticles had excellent aerodynamic properties, making them suitable for pulmonary aerosol delivery. The bioavailability of sCT after aerosol delivery as sCT and AAT-loaded composite microparticles to rats was 4-times higher than that of sCT solution. PMID:26692360

  7. International Symposium on Airborne Geophysics

    NASA Astrophysics Data System (ADS)

    Mogi, Toru; Ito, Hisatoshi; Kaieda, Hideshi; Kusunoki, Kenichiro; Saltus, Richard W.; Fitterman, David V.; Okuma, Shigeo; Nakatsuka, Tadashi

    2006-05-01

    Airborne geophysics can be defined as the measurement of Earth properties from sensors in the sky. The airborne measurement platform is usually a traditional fixed-wing airplane or helicopter, but could also include lighter-than-air craft, unmanned drones, or other specialty craft. The earliest history of airborne geophysics includes kite and hot-air balloon experiments. However, modern airborne geophysics dates from the mid-1940s when military submarine-hunting magnetometers were first used to map variations in the Earth's magnetic field. The current gamut of airborne geophysical techniques spans a broad range, including potential fields (both gravity and magnetics), electromagnetics (EM), radiometrics, spectral imaging, and thermal imaging.

  8. Controlling protein release using biodegradable microparticles

    NASA Astrophysics Data System (ADS)

    Kline, Benjamin Patrick

    Research in the field of protein therapeutics has exploded over the past decade and continues to grow in both academia and in industry. Protein drugs have advantages of being highly specific and highly active making them coveted targets for high profile disease states like cancer and multiple sclerosis. Unfortunately, their many advantages are complemented by their obstacles. Because proteins are highly active and highly specific, the window between efficacy and toxicity is very narrow and drug development can be long and arduous. In addition, protein activity is dependent on its specific folding conformation that is easily disrupted by a variety of development processes. This research aimed to identify microparticle formulations to control protein release and also to determine which formulation parameters affected burst release, encapsulation, and steady-state release the most. It was found that polymer type and composition were two of the most important factors. Long-term controlled release of bovine serum albumin (BSA) was achieved as well as a wide variety of release profiles. A method was identified for micronizing protein at low cost to retain activity and coacervation was evaluated as a method for preparing protein loaded microspheres. This research provides a basis from which researchers can create better controlled release formulations for future protein therapeutics.

  9. Shape-tunable core-shell microparticles.

    PubMed

    Klein, Matthias K; Saenger, Nicolai R; Schuetter, Stefan; Pfleiderer, Patrick; Zumbusch, Andreas

    2014-10-28

    Colloidal polymer particles are an important class of materials finding use in both everyday and basic research applications. Tailoring their composition, shape, and functionality is of key importance. In this article, we describe a new class of shape-tunable core-shell microparticles. They are composed of a cross-linked polystyrene (PS) core and a poly(methyl methacrylate) (PMMA) shell of varying thickness. In the first step, we prepared highly cross-linked PS cores, which are subsequently transferred into a nonpolar dispersant. They serve as the seed dispersion for a nonaqueous dispersion polymerization to generate the PMMA shell. The shape of the particles can subsequently be manipulated. After the shell growth stage, the spherical PS/PMMA core-shell colloids exhibit an uneven and wrinkled surface. An additional tempering procedure allows for smoothing the surface of the core-shell colloids. This results in polymer core-shell particles with a perfectly spherical shape. In addition to this thermal smoothing of the PMMA shell, we generated a selection of shape-anisotropic core-shell particles using a thermomechanical stretching procedure. Because of the unique constitution, we can selectively interrogate molecular vibrations in the PS core or the PMMA shell of the colloids using nonlinear optical microscopy techniques. This is of great interest because no photobleaching occurs, such that the particles can be tracked in real space over long times.

  10. [Fluorescence polarization immunoassay and microparticle enzyme immunoassay].

    PubMed

    Suguri, M; Hirose, N; Myoga, A; Doss, R; Tatsumi, N

    1996-11-01

    We describe a new clinical laboratory instrument, the Abbott AxSYM, which provides random- and continuous-access testing for immunoassays, 20 onboard reagents, primary tube sampling, and a throughput of 80 to 120 tests per hour. The AxSYM incorporates three separate analytical technologies for processing immunoassays: microparticle enzyme immunoassay, fluorescence polarization immunoassay, and a novel technology known as ion-capture immunoassay. The system incorporates both common and technology-specific subsystems controlled by a real-time software scheduling processor. Tests can be processed in one- or two-step sandwich or competitive formats, with variable pipetting steps, incubation periods, optical read formats, and wash sequences. Menu capabilities include test for hepatitis, retrovirus, tumor markers, fertility markers, thyroid functions, and therapeutic drugs. The time to first result is 15 approximately 25 min for most routine assay and < or = 15 min for stat assays (i.e., creatine kinase MB isoenzyme, human chorionic gonadotropin beta subunit, and therapeutic drugs). AxSYM assay performance for 23 assays was comparable with that of the Abbott IMx and TDx analyzers; specimen correlation data had correlation from 0.99 to 1.10. Within-run imprecision (CV) was 1.5% to 11.4%, with most assays (19 of 23) demonstrating CVs < or = 8.0%.

  11. Photoreactivation in Airborne Mycobacterium parafortuitum

    PubMed Central

    Peccia, Jordan; Hernandez, Mark

    2001-01-01

    Photoreactivation was observed in airborne Mycobacterium parafortuitum exposed concurrently to UV radiation (254 nm) and visible light. Photoreactivation rates of airborne cells increased with increasing relative humidity (RH) and decreased with increasing UV dose. Under a constant UV dose with visible light absent, the UV inactivation rate of airborne M. parafortuitum cells decreased by a factor of 4 as RH increased from 40 to 95%; however, under identical conditions with visible light present, the UV inactivation rate of airborne cells decreased only by a factor of 2. When irradiated in the absence of visible light, cellular cyclobutane thymine dimer content of UV-irradiated airborne M. parafortuitum and Serratia marcescens increased in response to RH increases. Results suggest that, unlike in waterborne bacteria, cyclobutane thymine dimers are not the most significant form of UV-induced DNA damage incurred by airborne bacteria and that the distribution of DNA photoproducts incorporated into UV-irradiated airborne cells is a function of RH. PMID:11526027

  12. Effects of ezetimibe on endothelial progenitor cells and microparticles in high-risk patients.

    PubMed

    Lins, Lívia Campos Amaral; França, Carolina Nunes; Fonseca, Francisco Antonio Helfenstein; Barbosa, Simone Pinto Melo; Matos, Lívia Nascimento; Aguirre, Ana Carolina; Bianco, Henrique Tria; do Amaral, Jonatas Bussador; Izar, Maria Cristina

    2014-09-01

    Imbalance on endothelial turnover can predict cardiovascular outcomes. We aimed at evaluating the effects of lipid-modifying therapies on circulating endothelial progenitor cells (EPCs), endothelial microparticles (EMPs), and platelet microparticles (PMPs) in high cardiovascular risk subjects with elevated C-reactive protein (CRP). Sixty-three individuals with coronary heart disease (CHD) or CHD risk equivalent on stable statin therapy, with LDL-cholesterol <100 mg/dL and CRP ≥ 2.0 mg/L were selected. After a 4-week run-in period with atorvastatin 10 mg, those with persistent CRP ≥ 2.0 mg/L were randomized to another 4-week treatment period with atorvastatin 40 mg, ezetimibe 10 mg or atorvastatin 40 mg/ezetimibe 10 mg. EPC (CD34(+)/CD133(+)/KDR(+)), EMP (CD51(+)), and PMP (CD42(+)/CD31(+)) were quantified by flow cytometry. Atorvastatin 40 mg and atorvastatin 40 mg/ezetimibe 10 mg reduced LDL-cholesterol (P < 0.001, paired T test, vs. baseline). Combined therapy, but not ezetimibe reduced CRP. CD34(+)/KDR(+) EPC were reduced after ezetimibe alone (P = 0.011 vs. baseline, Wilcoxon test) or combined with atorvastatin (P = 0.016 vs. baseline, Wilcoxon test). In addition, ezetimibe increased CD51(+) EMP (P = 0.017 vs. baseline, Wilcoxon test). No correlations between these markers and LDL-cholesterol or CRP were observed. These results contribute to understand the link between inflammation and vascular homeostasis and highlight the broader benefit of statins decreasing inflammation and preventing microparticles release, an effect not observed with ezetimibe alone.

  13. Fabrication and characterization of carboxymethyl cellulose novel microparticles for bone tissue engineering.

    PubMed

    Gaihre, Bipin; Jayasuriya, Ambalangodage C

    2016-12-01

    In this study we developed carboxymethyl cellulose (CMC) microparticles through ionic crosslinking with the aqueous ion complex of zirconium (Zr) and further complexing with chitosan (CS) and determined the physio-chemical and biological properties of these novel microparticles. In order to assess the role of Zr, microparticles were prepared in 5% and 10% (w/v) zirconium tetrachloride solution. Scanning electron microscopy (SEM) with energy dispersive X-ray spectrometer (EDS) results showed that Zr was uniformly distributed on the surface of the microparticles as a result of which uniform groovy surface was obtained. We found that Zr enhances the surface roughness of the microparticles and stability studies showed that it also increases the stability of microparticles in phosphate buffered saline. The crosslinking of anionic CMC with cationic Zr and CS was confirmed by Fourier transform infrared spectroscopy (FTIR) results. The response of murine pre-osteoblasts (OB-6) when cultured with microparticles was investigated. Live/dead cell assay showed that microparticles did not induce any cytotoxic effects as cells were attaching and proliferating on the well plate as well as along the surface of microparticles. In addition, SEM images showed that microparticles support the attachment of cells and they appeared to be directly interacting with the surface of microparticle. Within 10days of culture most of the top surface of microparticles was covered with a layer of cells indicating that they were proliferating well throughout the surface of microparticles. We observed that Zr enhances the cell attachment and proliferation as more cells were present on microparticles with 10% Zr. These promising results show the potential applications of CMC-Zr microparticles in bone tissue engineering. PMID:27612767

  14. Microfabrication of curcumin-loaded microparticles using coaxial electrohydrodynamic atomization

    NASA Astrophysics Data System (ADS)

    Yuan, Shuai; Si, Ting; Liu, Zhongfa; Xu, Ronald X.

    2014-03-01

    Encapsulation of curcumin in PLGA microparticles is performed by a coaxial electrohydrodynamic atomization device. To optimize the process, the effects of different control parameters on morphology and size distribution of resultant microparticles are studied systemically. Four main flow modes are identified as the applied electric field intensity increases. The stable cone-jet configuration is found to be available for fabricating monodisperse microparticles with core-shell structures. The results are compared with those observed in traditional emulsion. The drug-loading efficiency is also checked. The present system is advantageous for the enhancement of particle size distribution and drug-loading efficiency in various applications such as drug delivery, biomedicine and image-guided therapy.

  15. Electrosprayed inulin microparticles for microbiota triggered targeting of colon.

    PubMed

    Jain, Arvind K; Sood, Vishesh; Bora, Meghali; Vasita, Rajesh; Katti, Dhirendra S

    2014-11-01

    Inulin, a naturally occurring polysaccharide, was acetylated to make it processable by electrospraying, a facile and single step method for microparticle fabrication. Electrospraying process parameters were optimized for fabrication of spherical and monodisperse indomethacin (IDM) loaded inulin acetate (INA) microparticles. The apparent entrapment efficiency of IDM was determined to be 100%, whereas working encapsulation efficiency was estimated to be 35.39 ± 1.63%. Differential scanning calorimetry and X-ray diffraction analysis confirmed molecular dispersion of IDM in an amorphous state within the INA matrix. Finally, the results from in vitro release study performed in simulated gastro-intestinal fluids demonstrated that IDM was released only in simulated colonic fluid that contained inulinase. Therefore, this study demonstrates that acetylation of inulin does not alter its susceptibility to inulinase and that microparticles fabricated from INA can be developed as a colon targeting drug delivery system.

  16. Electrosprayed inulin microparticles for microbiota triggered targeting of colon.

    PubMed

    Jain, Arvind K; Sood, Vishesh; Bora, Meghali; Vasita, Rajesh; Katti, Dhirendra S

    2014-11-01

    Inulin, a naturally occurring polysaccharide, was acetylated to make it processable by electrospraying, a facile and single step method for microparticle fabrication. Electrospraying process parameters were optimized for fabrication of spherical and monodisperse indomethacin (IDM) loaded inulin acetate (INA) microparticles. The apparent entrapment efficiency of IDM was determined to be 100%, whereas working encapsulation efficiency was estimated to be 35.39 ± 1.63%. Differential scanning calorimetry and X-ray diffraction analysis confirmed molecular dispersion of IDM in an amorphous state within the INA matrix. Finally, the results from in vitro release study performed in simulated gastro-intestinal fluids demonstrated that IDM was released only in simulated colonic fluid that contained inulinase. Therefore, this study demonstrates that acetylation of inulin does not alter its susceptibility to inulinase and that microparticles fabricated from INA can be developed as a colon targeting drug delivery system. PMID:25129739

  17. Composition analyzer for microparticles using a spark ion source

    NASA Technical Reports Server (NTRS)

    Auer, S.; Berg, O. E.

    1975-01-01

    Iron microparticles were fired onto a capacitor-type microparticle detector which responded to an impact with a spark discharge. Ion currents were extracted from the spark and analyzed in a time-of-flight mass spectrometer. The mass spectra showed the elements of both detector and particle materials. The total extracted ion current was typically 10 A within a period of 100 nsec, indicating very efficient vaporization of the particle and ionization of the vapor. Potential applications include research on cosmic dust, atmospheric aerosols and cloud droplets, particles ejected by rocket or jet engines, by machining processes or by nuclear bomb explosions.

  18. Red blood cell-derived microparticles: An overview.

    PubMed

    Westerman, Maxwell; Porter, John B

    2016-07-01

    The red blood cell (RBC) is historically the original parent cell of microparticles (MPs). In this overview, we describe the discovery and the early history of red cell-derived microparticles (RMPs) and present an overview of the evolution of RMP. We report the formation, characteristics, effects of RMP and factors which may affect RMP evaluation. The review examines RMP derived from both normal and pathologic RBC. The pathologic RBC studies include sickle cell anemia (SCA), sickle cell trait (STr), thalassemia intermedia (TI), hereditary spherocytosis (HS), hereditary elliptocytosis (HE), hereditary stomatocytosis (HSt) and glucose-6-phosphate dehydrogenase deficiency (G6PD). PMID:27282583

  19. Dielectrophoretic Manipulation and Separation of Microparticles Using Microarray Dot Electrodes

    PubMed Central

    Yafouz, Bashar; Kadri, Nahrizul Adib; Ibrahim, Fatimah

    2014-01-01

    This paper introduces a dielectrophoretic system for the manipulation and separation of microparticles. The system is composed of five layers and utilizes microarray dot electrodes. We validated our system by conducting size-dependent manipulation and separation experiments on 1, 5 and 15 μm polystyrene particles. Our findings confirm the capability of the proposed device to rapidly and efficiently manipulate and separate microparticles of various dimensions, utilizing positive and negative dielectrophoresis (DEP) effects. Larger size particles were repelled and concentrated in the center of the dot by negative DEP, while the smaller sizes were attracted and collected by the edge of the dot by positive DEP. PMID:24705632

  20. The role of microparticles in chronic obstructive pulmonary disease.

    PubMed

    Takahashi, Toru; Kubo, Hiroshi

    2014-01-01

    Accumulating evidence suggests that cell injury in lung tissues is closely connected to disease progression in chronic obstructive pulmonary disease (COPD). Microparticles (MPs) are shed membrane vesicles that are released from platelets, leukocytes, red blood cells, and endothelial cells when these cells are activated or undergo apoptosis under inflammatory conditions. Based on increasing evidence that endothelial injury in the pulmonary capillary vasculature leads to lung destruction, and because cardiovascular diseases are the main cause of death among individuals with COPD, endothelial MPs (EMPs) are now receiving attention as potential biomarkers for COPD. There are eight types of EMPs which are defined by the presence of different endothelial markers on the cell membrane: vascular endothelial-cadherin; platelet endothelial cell adhesion molecule; melanoma cell adhesion molecule; E-selectin; CD51; CD105; von Willebrand factor; and CD143 EMPs. Vascular endothelial-cadherin, platelet endothelial cell adhesion molecule, and E-selectin EMPs are increased in patients with stable COPD and are further increased in patients with exacerbated COPD compared to non-COPD patients. In addition, the levels of these three EMPs in patients with stable COPD are significantly correlated with lung destruction and airflow limitation. These results indicate that endothelial injury is closely connected to the pathophysiology of COPD. Interestingly, the variations in the levels of the eight EMP subtypes were not identical with changes in patient condition. Although the clinical significance of the differences in these eight EMP subtypes remains unclear, evaluating the expression pattern of endothelial antigens on circulating MPs might predict the presence and degree of endothelial injury in COPD patients. In addition, circulating MPs are proposed to have several physiological functions in vivo, such as intercellular crosstalk; the increase in EMPs in COPD seems to play a role in the

  1. [Air-borne disease].

    PubMed

    Lameiro Vilariño, Carmen; del Campo Pérez, Victor M; Alonso Bürger, Susana; Felpeto Nodar, Irene; Guimarey Pérez, Rosa; Pérez Alvarellos, Alberto

    2003-11-01

    Respiratory protection is a factor which worries nursing professionals who take care of patients susceptible of transmitting microorganisms through the air more as every day passes. This type of protection covers the use of surgical or hygienic masks against the transmission of infection by airborne drops to the use of highly effective masks or respirators against the transmission of airborne diseases such as tuberculosis or SARS, a recently discovered disease. The adequate choice of this protective device and its correct use are fundamental in order to have an effective protection for exposed personnel. The authors summarize the main protective respiratory devices used by health workers, their characteristics and degree of effectiveness, as well as the circumstances under which each device is indicated for use. PMID:14705591

  2. Platelet and not erythrocyte microparticles are procoagulant in transfused thalassaemia major patients.

    PubMed

    Agouti, Imane; Cointe, Sylvie; Robert, Stéphane; Judicone, Coralie; Loundou, Anderson; Driss, Fathi; Brisson, Alain; Steschenko, Dominique; Rose, Christian; Pondarré, Corinne; Bernit, Emmanuelle; Badens, Catherine; Dignat-George, Françoise; Lacroix, Romaric; Thuret, Isabelle

    2015-11-01

    The level of circulating platelet-, erythrocyte-, leucocyte- and endothelial-derived microparticles detected by high-sensitivity flow cytometry was investigated in 37 β-thalassaemia major patients receiving a regular transfusion regimen. The phospholipid procoagulant potential of the circulating microparticles and the microparticle-dependent tissue factor activity were evaluated. A high level of circulating erythrocyte- and platelet-microparticles was found. In contrast, the number of endothelial microparticles was within the normal range. Platelet microparticles were significantly higher in splenectomized than in non-splenectomized patients, independent of platelet count (P < 0·001). Multivariate analysis indicated that phospholipid-dependent procoagulant activity was influenced by both splenectomy (P = 0·001) and platelet microparticle level (P < 0·001). Erythrocyte microparticles were not related to splenectomy, appear to be devoid of proper procoagulant activity and no relationship between their production and haemolysis, dyserythropoiesis or oxidative stress markers could be established. Intra-microparticle labelling with anti-HbF antibodies showed that they originate only partially (median of 28%) from thalassaemic erythropoiesis. In conclusion, when β-thalassaemia major patients are intensively transfused, the procoagulant activity associated with thalassaemic erythrocyte microparticles is probably diluted by transfusions. In contrast, platelet microparticles, being both more elevated and more procoagulant, especially after splenectomy, may contribute to the residual thrombotic risk reported in splenectomized multi-transfused β-thalassaemia major patients.

  3. Novel polymer-grafted starch microparticles for mucosal delivery of vaccines.

    PubMed Central

    Heritage, P L; Loomes, L M; Jianxiong, J; Brook, M A; Underdown, B J; McDermott, M R

    1996-01-01

    Recent studies have demonstrated that systemic and mucosal administration of soluble antigens in biodegradable microparticles can potentiate antigen-specific humoral and cellular immune responses. However, current microparticle formulations are not adequate for all vaccine antigens, necessitating the further development of microparticle carrier systems. In this study, we developed a novel microparticle fabrication technique in which human serum albumin (HSA) was entrapped in starch microparticles grafted with 3-(triethoxysilyl)-propyl-terminated polydimethylsiloxane (TS-PDMS), a biocompatible silicone polymer. The immunogenicity of HSA was preserved during the microparticle fabrication process. Following intraperitoneal immunization of mice, TS-PDMS-grafted microparticles (MP) dramatically enhanced serum IgG responses compared with ungrafted MP and soluble HSA alone (P < 0.001). When delivered orally, both TS-PDMS-grafted and ungrafted microparticles elicited HSA-specific IgA responses in gut secretions, in contrast to orally administered soluble antigen. Indeed, TS-PDMS-grafted microparticles stimulated significantly stronger serum IgG (P < 0.005) and IgA (P < 0.001) responses compared with those elicited by ungrafted microparticles. These findings indicate that TS-PDMS-grafted starch microparticles have potential as systemic and mucosal vaccine delivery vehicles. Images Figure 1 Figure 2 PMID:8707344

  4. Interfacial tension based on-chip extraction of microparticles confined in microfluidic Stokes flows

    NASA Astrophysics Data System (ADS)

    Huang, Haishui; He, Xiaoming

    2014-10-01

    Microfluidics involving two immiscible fluids (oil and water) has been increasingly used to produce hydrogel microparticles with wide applications. However, it is difficult to extract the microparticles out of the microfluidic Stokes flows of oil that have a Reynolds number (the ratio of inertia to viscous force) much less than one, where the dominant viscous force tends to drive the microparticles to move together with the surrounding oil. Here, we present a passive method for extracting hydrogel microparticles in microfluidic Stokes flow from oil into aqueous extracting solution on-chip by utilizing the intrinsic interfacial tension between oil and the microparticles. We further reveal that the thickness of an "extended confining layer" of oil next to the interface between oil and aqueous extracting solution must be smaller than the radius of microparticles for effective extraction. This method uses a simple planar merging microchannel design that can be readily fabricated and further integrated into a fluidic system to extract microparticles for wide applications.

  5. MLS airborne antenna research

    NASA Technical Reports Server (NTRS)

    Yu, C. L.; Burnside, W. D.

    1975-01-01

    The geometrical theory of diffraction was used to analyze the elevation plane pattern of on-aircraft antennas. The radiation patterns for basic elements (infinitesimal dipole, circumferential and axial slot) mounted on fuselage of various aircrafts with or without radome included were calculated and compared well with experimental results. Error phase plots were also presented. The effects of radiation patterns and error phase plots on the polarization selection for the MLS airborne antenna are discussed.

  6. Airborne forest fire research

    NASA Technical Reports Server (NTRS)

    Mattingly, G. S.

    1974-01-01

    The research relating to airborne fire fighting systems is reviewed to provide NASA/Langley Research Center with current information on the use of aircraft in forest fire operations, and to identify research requirements for future operations. A literature survey, interview of forest fire service personnel, analysis and synthesis of data from research reports and independent conclusions, and recommendations for future NASA-LRC programs are included.

  7. Mutagenicity of airborne particles.

    PubMed

    Chrisp, C E; Fisher, G L

    1980-09-01

    The physical and chemical properties of airborne particles are important for the interpretation of their potential biologic significance as genotoxic hazards. For polydisperse particle size distributions, the smallest, most respirable particles are generally the most mutagenic. Particulate collection for testing purposes should be designed to reduce artifact formation and allow condensation of mutagenic compounds. Other critical factors such as UV irradiation, wind direction, chemical reactivity, humidity, sample storage, and temperature of combustion are important. Application of chemical extraction methods and subsequent class fractionation techniques influence the observed mutagenic activity. Particles from urban air, coal fly ash, automobile and diesel exhaust, agricultural burning and welding fumes contain primarily direct-acting mutagens. Cigarette smoke condensate, smoke from charred meat and protein pyrolysates, kerosene soot and cigarette smoke condensates contain primarily mutagens which require metabolic activation. Fractionation coupled with mutagenicity testing indicates that the most potent mutagens are found in the acidic fractions of urban air, coal fly ash, and automobile diesel exhaust, whereas mutagens in rice straw smoke and cigarette smoke condensate are found primarily in the basic fractions. The interaction of the many chemical compounds in complex mixtures from airborne particles is likely to be important in determining mutagenic or comutagenic potentials. Because the mode of exposure is generally frequent and prolonged, the presence of tumor-promoting agents in complex mixtures may be a major factor in evaluation of the carcinogenic potential of airborne particles.

  8. Mammalian airborne allergens.

    PubMed

    Aalberse, Rob C

    2014-01-01

    Historically, horse dandruff was a favorite allergen source material. Today, however, allergic symptoms due to airborne mammalian allergens are mostly a result of indoor exposure, be it at home, at work or even at school. The relevance of mammalian allergens in relation to the allergenic activity of house dust extract is briefly discussed in the historical context of two other proposed sources of house dust allergenic activity: mites and Maillard-type lysine-sugar conjugates. Mammalian proteins involved in allergic reactions to airborne dust are largely found in only 2 protein families: lipocalins and secretoglobins (Fel d 1-like proteins), with a relatively minor contribution of serum albumins, cystatins and latherins. Both the lipocalin and the secretoglobin family are very complex. In some instances this results in a blurred separation between important and less important allergenic family members. The past 50 years have provided us with much detailed information on the genomic organization and protein structure of many of these allergens. However, the complex family relations, combined with the wide range of post-translational enzymatic and non-enzymatic modifications, make a proper qualitative and quantitative description of the important mammalian indoor airborne allergens still a significant proteomic challenge. PMID:24925404

  9. Airborne wireless communication systems, airborne communication methods, and communication methods

    DOEpatents

    Deaton, Juan D.; Schmitt, Michael J.; Jones, Warren F.

    2011-12-13

    An airborne wireless communication system includes circuitry configured to access information describing a configuration of a terrestrial wireless communication base station that has become disabled. The terrestrial base station is configured to implement wireless communication between wireless devices located within a geographical area and a network when the terrestrial base station is not disabled. The circuitry is further configured, based on the information, to configure the airborne station to have the configuration of the terrestrial base station. An airborne communication method includes answering a 911 call from a terrestrial cellular wireless phone using an airborne wireless communication system.

  10. Airborne Submillimeter Spectroscopy

    NASA Technical Reports Server (NTRS)

    Zmuidzinas, J.

    1998-01-01

    This is the final technical report for NASA-Ames grant NAG2-1068 to Caltech, entitled "Airborne Submillimeter Spectroscopy", which extended over the period May 1, 1996 through January 31, 1998. The grant was funded by the NASA airborne astronomy program, during a period of time after the Kuiper Airborne Observatory was no longer operational. Instead. this funding program was intended to help develop instrument concepts and technology for the upcoming SOFIA (Stratospheric Observatory for Infrared Astronomy) project. SOFIA, which is funded by NASA and is now being carried out by a consortium lead by USRA (Universities Space Research Association), will be a 747 aircraft carrying a 2.5 meter diameter telescope. The purpose of our grant was to fund the ongoing development of sensitive heterodyne receivers for the submillimeter band (500-1200 GHz), using sensitive superconducting (SIS) detectors. In 1997 July we submitted a proposal to USRA to construct a heterodyne instrument for SOFIA. Our proposal was successful [1], and we are now continuing our airborne astronomy effort with funding from USRA. A secondary purpose of the NAG2-1068 grant was to continue the anaIN'sis of astronomical data collected with an earlier instrument which was flown on the NASA Kuiper Airborne Observatory (KAO). The KAO instrument and the astronomical studies which were carried out with it were supported primarily under another grant, NAG2-744, which extended over October 1, 1991 through Januarv 31, 1997. For a complete description of the astronomical data and its anailysis, we refer the reader to the final technical report for NAG2-744, which was submitted to NASA on December 1. 1997. Here we report on the SIS detector development effort for SOFIA carried out under NAG2-1068. The main result of this effort has been the demonstration of SIS mixers using a new superconducting material niobium titanium nitride (NbTiN), which promises to deliver dramatic improvements in sensitivity in the 700

  11. Characterisation of inorganic microparticles in pigment cells of human gut associated lymphoid tissue.

    PubMed Central

    Powell, J J; Ainley, C C; Harvey, R S; Mason, I M; Kendall, M D; Sankey, E A; Dhillon, A P; Thompson, R P

    1996-01-01

    Macrophages at the base of human gut associated lymphoid tissue (GALT), become loaded early in life with dark granular pigment that is rich in aluminium, silicon, and titanium. The molecular characteristics, intracellular distribution, and source of this pigment is described. Laser scanning and electron microscopy showed that pigmented macrophages were often closely related to collagen fibres and plasma cells in GALT of both small and large intestine and contained numerous phagolysosomes, previously described as granules, that are rich in electron dense submicron sized particles. Morphological assessment, x ray microanalysis, and image electron energy loss spectroscopy showed three distinct types of microparticle: type I - spheres of titanium dioxide, 100-200 nm diameter, characterised as the synthetic food-additive polymorph anatase; type II - aluminosilicates, < 100-400 nm in length, generally of flaky appearance, often with adsorbed surface iron, and mostly characteristic of the natural clay mineral kaolinite; and type III - mixed environmental silicates without aluminium, 100-700 nm in length and of variable morphology. Thus, this cellular pigment that is partly derived from food additives and partly from the environment is composed of inert inorganic microparticles and loaded into phagolysosomes of macrophages within the GALT of all human subjects. These observations suggest that the pathogenicity of this pigment should be further investigated since, in susceptible individuals, the same intracellular distribution of these three types of submicron particle causes chronic latent granulomatous inflammation. Images Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 7 PMID:8675092

  12. Inhalable Antitubercular Therapy Mediated by Locust Bean Gum Microparticles.

    PubMed

    Alves, Ana D; Cavaco, Joana S; Guerreiro, Filipa; Lourenço, João P; Rosa da Costa, Ana M; Grenha, Ana

    2016-05-28

    Tuberculosis remains a major global health problem and alternative therapeutic approaches are needed. Considering the high prevalence of lung tuberculosis (80% of cases), the pulmonary delivery of antitubercular drugs in a carrier system capable of reaching the alveoli, being recognised and phagocytosed by alveolar macrophages (mycobacterium hosts), would be a significant improvement to current oral drug regimens. Locust bean gum (LBG) is a polysaccharide composed of galactose and mannose residues, which may favour specific recognition by macrophages and potentiate phagocytosis. LBG microparticles produced by spray-drying are reported herein for the first time, incorporating either isoniazid or rifabutin, first-line antitubercular drugs (association efficiencies >82%). Microparticles have adequate theoretical properties for deep lung delivery (aerodynamic diameters between 1.15 and 1.67 μm). The cytotoxic evaluation in lung epithelial cells (A549 cells) and macrophages (THP-1 cells) revealed a toxic effect from rifabutin-loaded microparticles at the highest concentrations, but we may consider that these were very high comparing with in vivo conditions. LBG microparticles further evidenced strong ability to be captured by macrophages (percentage of phagocytosis >94%). Overall, the obtained data indicated the potential of the proposed system for tuberculosis therapy.

  13. Uptake of inert microparticles in normal and immune deficient mice.

    PubMed

    Smyth, S H; Feldhaus, S; Schumacher, U; Carr, K E

    2008-01-01

    Intestinal microparticle uptake is important for drug delivery, environmental pollution and multiple organ dysfunction syndrome. This paper explores further whether uptake occurs at mucosa associated lymphoid tissue (MALT) via the microfold (M) cells of Peyer's patch domes or through villous epithelium. It does this by comparing the results of exposure of either severe combined immunodeficient (SCID) mice (lacking MALT) or normal BALBc mice, to oral gavage with 2 microm fluorescent latex microparticles. At 5 and 30 min after gavage, full circumference samples along the small intestine were processed for fluorescence microscopy and microparticle numbers were collected for surface and tissue sites. Uptake occurred in both BALBc and SCID mice within 5 min of particle administration and increased further in the following 25 min. In BALBc mice, almost all particles (96%) are in non-MALT sites in MALT circumference samples, with very few at the domes: uptake was also substantial in entirely villous samples. In SCID mice, particle numbers were only slightly lower than those of the BALBc mice, and occurred exclusively by the villous route. These findings confirm that the villous uptake route must be considered when assessing the extent of the dose delivered following pharmaceutical or toxicological oral exposure to microparticles. PMID:17723283

  14. Mucoadhesive Microparticles for Gastroretentive Delivery: Preparation, Biodistribution and Targeting Evaluation

    PubMed Central

    Hou, Jing-Yi; Gao, Li-Na; Meng, Fan-Yun; Cui, Yuan-Lu

    2014-01-01

    The aim of this research was to prepare and characterize alginate-chitosan mucoadhesive microparticles containing puerarin. The microparticles were prepared by an emulsification-internal gelatin method using a combination of chitosan and Ca2+ as cationic components and alginate as anions. Surface morphology, particle size, drug loading, encapsulation efficiency and swelling ratio, in vitro drug released, in vitro evaluation of mucoadhesiveness and Fluorescence imaging of the gastrointestinal tract were determined. After optimization of the formulation, the encapsulation efficiency was dramatically increased from 70.3% to 99.2%, and a highly swelling ratio was achieved with a change in particle size from 50.3 ± 11.2 μm to 124.7 ± 25.6 μm. In ethanol induced gastric ulcers, administration of puerarin mucoadhesive microparticles at doses of 150 mg/kg, 300 mg/kg, 450 mg/kg and 600 mg/kg body weight prior to ethanol ingestion significantly protected the stomach ulceration. Consequently, significant changes were observed in inflammatory cytokines, such as prostaglandin E2 (PGE2), tumor necrosis factor (TNF-α), interleukin 6 (IL-6), and interleukin1β (IL-1β), in stomach tissues compared with the ethanol control group. In conclusion, core-shell type pH-sensitive mucoadhesive microparticles loaded with puerarin could enhance puerarin bioavailability and have the potential to alleviate ethanol-mediated gastric ulcers. PMID:25470180

  15. Mechanically robust microfluidics and bulk wave acoustics to sort microparticles

    NASA Astrophysics Data System (ADS)

    Dauson, Erin R.; Gregory, Kelvin B.; Greve, David W.; Healy, Gregory P.; Oppenheim, Irving J.

    2016-04-01

    Sorting microparticles (or cells, or bacteria) is significant for scientific, medical and industrial purposes. Research groups have used lithium niobate SAW devices to produce standing waves, and then to align microparticles at the node lines in polydimethylsiloxane (PDMS, silicone) microfluidic channels. The "tilted angle" (skewed) configuration is a recent breakthrough producing particle trajectories that cross multiple node lines, making it practical to sort particles. However, lithium niobate wafers and PDMS microfluidic channels are not mechanically robust. We demonstrate "tilted angle" microparticle sorting in novel devices that are robust, rapidly prototyped, and manufacturable. We form our microfluidic system in a rigid polymethyl methacrylate (PMMA, acrylic) prism, sandwiched by lead-zirconium-titanate (PZT) wafers, operating in through-thickness mode with inertial backing, that produce standing bulk waves. The overall configuration is compact and mechanically robust, and actuating PZT wafers in through-thickness mode is highly efficient. Moving to this novel configuration introduced new acoustics questions involving internal reflections, but we show experimental images confirming the intended nodal geometry. Microparticles in "tilted angle" devices display undulating trajectories, where deviation from the straight path increases with particle diameter and with excitation voltage to create the mechanism by which particles are sorted. We show a simplified analytical model by which a "phase space" is constructed to characterize effective particle sorting, and we compare our experimental data to the predictions from that simplified model; precise correlation is not expected and is not observed, but the important physical trends from the model are paralleled in the measured particle trajectories.

  16. Biodegradable nanocomposite microparticles as drug delivering injectable cell scaffolds.

    PubMed

    Wen, Yanhong; Gallego, Monica Ramos; Nielsen, Lene Feldskov; Jorgensen, Lene; Everland, Hanne; Møller, Eva Horn; Nielsen, Hanne Mørck

    2011-11-30

    Injectable cell scaffolds play a dual role in tissue engineering by supporting cellular functions and delivering bioactive molecules. The present study aimed at developing biodegradable nanocomposite microparticles with sustained drug delivery properties thus potentially being suitable for autologous stem cell therapy. Semi-crystalline poly(l-lactide/dl-lactide) (PLDL70) and poly(l-lactide-co-glycolide) (PLGA85) were used to prepare nanoparticles by the double emulsion method. Uniform and spherical nanoparticles were obtained at an average size of 270-300 nm. The thrombin receptor activator peptide-6 (TRAP-6) was successfully loaded in PLDL70 and PLGA85 nanoparticles. During the 30 days' release, PLDL70 nanoparticles showed sustainable release with only 30% TRAP-6 released within the first 15 days, while almost 80% TRAP-6 was released from PLGA85 nanoparticles during the same time interval. The release mechanism was found to depend on the crystallinity and composition of the nanoparticles. Subsequently, mPEG-PLGA nanocomposite microparticles containing PLDL70 nanoparticles were produced by the ultrasonic atomization method and evaluated to successfully preserve the intrinsic particulate properties and the sustainable release profile, which was identical to that of the nanoparticles. Good cell adhesion of the human fibroblasts onto the nanocomposite microparticles was observed, indicating the desired cell biocompatibility. The presented results thus demonstrate the development of nanocomposite microparticles tailored for sustainable drug release for application as injectable cell scaffolds. PMID:21787815

  17. Inhalable Antitubercular Therapy Mediated by Locust Bean Gum Microparticles.

    PubMed

    Alves, Ana D; Cavaco, Joana S; Guerreiro, Filipa; Lourenço, João P; Rosa da Costa, Ana M; Grenha, Ana

    2016-01-01

    Tuberculosis remains a major global health problem and alternative therapeutic approaches are needed. Considering the high prevalence of lung tuberculosis (80% of cases), the pulmonary delivery of antitubercular drugs in a carrier system capable of reaching the alveoli, being recognised and phagocytosed by alveolar macrophages (mycobacterium hosts), would be a significant improvement to current oral drug regimens. Locust bean gum (LBG) is a polysaccharide composed of galactose and mannose residues, which may favour specific recognition by macrophages and potentiate phagocytosis. LBG microparticles produced by spray-drying are reported herein for the first time, incorporating either isoniazid or rifabutin, first-line antitubercular drugs (association efficiencies >82%). Microparticles have adequate theoretical properties for deep lung delivery (aerodynamic diameters between 1.15 and 1.67 μm). The cytotoxic evaluation in lung epithelial cells (A549 cells) and macrophages (THP-1 cells) revealed a toxic effect from rifabutin-loaded microparticles at the highest concentrations, but we may consider that these were very high comparing with in vivo conditions. LBG microparticles further evidenced strong ability to be captured by macrophages (percentage of phagocytosis >94%). Overall, the obtained data indicated the potential of the proposed system for tuberculosis therapy. PMID:27240337

  18. Resonant propulsion of a microparticle by a surface wave

    NASA Astrophysics Data System (ADS)

    Maslov, A. V.; Astratov, V. N.; Bakunov, M. I.

    2013-05-01

    We investigate the electromagnetic force experienced by a microparticle supporting high-quality whispering gallery modes that are excited by a surface wave. Our theoretical approach is based on an analytical representation of the solution of the scattering problem with a subsequent numerical treatment. It accounts rigorously for the interaction of the microparticle with the waveguiding surface and allows us to establish the balances of electromagnetic power and momentum flow for the system. We show that the resonant excitation of the whispering gallery modes and suppression of the transmitted surface wave lead to an almost complete transformation of the momentum flow of the initial surface wave into the propelling force on the microparticle. The validation of the momentum balance justifies the definition of the momentum flow of the surface wave as the ratio of carried power and phase velocity. A simple approximate relation between the propelling force and the power of the transmitted surface wave is also introduced. The transverse force can be either attractive or repulsive depending on the particle-to-surface distance, particle size, and operating frequencies, and it can significantly exceed the value of the propelling force. A comparison with a microparticle excited by a plane wave is also included.

  19. Polymer-based microparticles in tissue engineering and regenerative medicine.

    PubMed

    Oliveira, Mariana B; Mano, João F

    2011-07-01

    Different types of biomaterials, processed into different shapes, have been proposed as temporary support for cells in tissue engineering (TE) strategies. The manufacturing methods used in the production of particles in drug delivery strategies have been adapted for the development of microparticles in the fields of TE and regenerative medicine (RM). Microparticles have been applied as building blocks and matrices for the delivery of soluble factors, aiming for the construction of TE scaffolds, either by fusion giving rise to porous scaffolds or as injectable systems for in situ scaffold formation, avoiding complicated surgery procedures. More recently, organ printing strategies have been developed by the fusion of hydrogel particles with encapsulated cells, aiming the production of organs in in vitro conditions. Mesoscale self-assembly of hydrogel microblocks and the use of leachable particles in three-dimensional (3D) layer-by-layer (LbL) techniques have been suggested as well in recent works. Along with innovative applications, new perspectives are open for the use of these versatile structures, and different directions can still be followed to use all the potential that such systems can bring. This review focuses on polymeric microparticle processing techniques and overviews several examples and general concepts related to the use of these systems in TE and RE applications. The use of materials in the development of microparticles from research to clinical applications is also discussed.

  20. Magnetic microparticles for harvesting Dunaliella tertiolecta microalgae

    NASA Astrophysics Data System (ADS)

    Manousakis, Emmanouil; Manariotis, Ioannis D.

    2016-04-01

    Microalgae based biofuels have been considered as a sustainable alternative to traditional fuels due to the higher biomass yield and lipid productivity, and the ability to be cultivated in non arable land making them not antagonistic with food supply chain. Due to the dilute nature of algal cultures and the small size of algae cells, the cost of microalgae harvesting is so far a bottleneck in microalgal based biofuel production. It is estimated that the algal recovery cost is at least 20-30% of the total biomass production cost. Various processes have been employed for the recovery of microalgal biomass, which include centrifugation, gravity separation, filtration, flocculation, and flotation. Recently, magnetophoric harvesting has received increased attention for algal separation, although it has been first applied for algal removal since the mid of 1970s. The magnetic separation process is based on bringing in contact the algal cells with the magnetic particles, and separating them from the liquid by an external magnetic force. The aim of this work was to investigate the harvesting of microalgae cells using Fe3O4 magnetic microparticles (MPs). Dunaliella tertiolecta was selected as a representative for marine microalgae. D. tertiolecta was cultivated under continuous artificial light, in 20 L flasks. Fe3O4 MPs were prepared by microwave irradiation of FeSO4 7H2O in an alkaline solution. Numerous batch and flow-through experiments were conducted in order to investigate the effect of the magnetic material addition on microalgae removal. Batch experiments were conducted examining different initial algal and MPs concentration, and algal culture volume. Flow-through experiments were conducted in a laboratory scale column made of Plexiglass. External magnetic field was applied by arranging at various points across the column length NdFeB magnets. Algal removal in flow-through experiments ranged from 70 to 85% depending on the initial MPs concentration and the hydraulic

  1. Charge contribution to patch-charged microparticle adhesion

    NASA Astrophysics Data System (ADS)

    Vallabh, Chaitanya Krishna Prasad; Vahdat, Armin Saeedi; Cetinkaya, Cetin

    2014-11-01

    Microparticle adhesion influenced by electrostatic charge has been a significant research interest for over past three decades or so in a wide spectrum of areas of interest from manufacturing (electrophotography, powder technology, metallurgy, and semi-conductor manufacturing) to natural phenomena (desert sandstorms and northern lights (auroras)). However, over the years, as a result of the strong discrepancies between the experimental adhesion measurements data and theoretical predictions, some key issues regarding the contributors of adhesion forces in charged microparticles and the nature of surface charge distribution still remain unresolved. In the current work, a non-contact ultrasonic approach is presented and employed for understanding the nature of charge distribution on a single microparticle and determining the effect of electrostatic charge on its adhesion in a non-invasive manner. From the vibrational spectra of the charged particle response to the ultrasonic substrate oscillations under various electrostatic loading conditions, three distinct shifting patterns of vibrational (rocking) resonance frequencies are observed for each level of applied substrate surface voltage, implying an un-symmetric force field on the particle, thus depicting non-uniform non-symmetric surface charge distribution on its surface. Also, a simple mathematical model was presented and employed for predicting the equivalent bulk charge on a single microparticle (toner) from resonance frequency shifts. In summary, it is found that the charge levels reported here are consistent with the previously published data, and it is demonstrated that, in a non-invasive manner, non-uniform charge distribution on a single microparticle can be observed and its total charge can be predicted.

  2. PHARUS airborne SAR concept

    NASA Astrophysics Data System (ADS)

    Snoeij, Paul; Pouwels, Henk; Koomen, Peter J.; Hoogeboom, Peter

    1995-11-01

    PHARUS (phased array universal SAR) is an airborne SAR concept which is being developed in the Netherlands. The PHARUS system differs from other airborne SARs by the use of a phased array antenna, which provides both for the flexibility in the design as well as for a compact, light-weight instrument that can be carried on small aircraft. The concept allows for the construction of airborne SAR systems on a common generic basis but tailored to specific user needs and can be seen as a preparation for future spaceborne SAR systems using solid state transmitters with electronically steerable phased array antenna. The whole approach is aimed at providing an economic and yet technically sophisticated solution to remote sensing or surveying needs of a specific user. The solid state phased array antenna consists of a collection of radiating patches; the design flexibility for a large part resides in the freedom to choose the number of patches, and thereby the essential radar performance parameters such as resolution and swath width. Another consequence of the use of the phased array antenna is the system's compactness and the possibility to rigidly mount it on a small aircraft. The use of small aircraft of course considerably improves the cost/benefit ratio of the use of airborne SAR. Flight altitude of the system is flexible between about 7,000 and 40,000 feet, giving much operational freedom within the meteo and airspace control limits. In the PHARUS concept the airborne segment is complemented by a ground segment, which consists of a SAR processor, possibly extended by a matching image processing package. (A quick look image is available in real-time on board the aircraft.) The SAR processor is UNIX based and runs on easily available hardware (SUN station). Although the additional image processing software is available, the SAR processing software is nevertheless designed to be able to interface with commercially available image processing software, as well as being able

  3. Airborne Oceanographic Lidar System

    NASA Technical Reports Server (NTRS)

    Bressel, C.; Itzkan, I.; Nunes, J. E.; Hoge, F.

    1977-01-01

    The Airborne Oceanographic Lidar (AOL), a spatially scanning range-gated device installed on board a NASA C-54 aircraft, is described. The AOL system is capable of measuring topographical relief or water depth (bathymetry) with a range resolution of plus or minus 0.3 m in the vertical dimension. The system may also be used to measure fluorescent spectral signatures from 3500 to 8000 A with a resolution of 100 A. Potential applications of the AOL, including sea state measurements, water transparency assessments, oil spill identification, effluent identification and crop cover assessment are also mentioned.

  4. Airborne concentrations of peanut protein.

    PubMed

    Johnson, Rodney M; Barnes, Charles S

    2013-01-01

    Food allergy to peanut is a significant health problem, and there are reported allergic reactions to peanuts despite not eating or having physical contact with peanuts. It is presumed that an allergic reaction may have occurred from inhalation of airborne peanut allergens. The purpose of this study was to detect the possible concentrations of airborne peanut proteins for various preparations and during specific activities. Separate Ara h 1 and Ara h 2 monoclonal enzyme-linked immunosorbent assays and a polyclonal sandwich enzyme immunoassay for peanuts were used to detect the amount of airborne peanut protein collected using a Spincon Omni 3000 air collector (Sceptor Industries, Inc., Kansas City, MO) under different peanut preparation methods and situations. Air samples were measured for multiple peanut preparations and scenarios. Detectable amounts of airborne peanut protein were measured using a whole peanut immunoassay when removing the shells of roasted peanut. No airborne peanut allergen (Ara h 1 or Ara h 2) or whole peanut protein above the LLD was measured in any of the other peanut preparation collections. Ara h 1, Ara h 2, and polyclonal peanut proteins were detected from water used to boil peanuts. Small amounts of airborne peanut protein were detected in the scenario of removing shells from roasted peanuts; however, Ara h 1 and Ara h 2 proteins were unable to be consistently detected. Although airborne peanut proteins were detected, the concentration of airborne peanut protein that is necessary to elicit a clinical allergic reaction is unknown.

  5. Airborne ballistic camera tracking systems

    NASA Technical Reports Server (NTRS)

    Redish, W. L.

    1976-01-01

    An operational airborne ballistic camera tracking system was tested for operational and data reduction feasibility. The acquisition and data processing requirements of the system are discussed. Suggestions for future improvements are also noted. A description of the data reduction mathematics is outlined. Results from a successful reentry test mission are tabulated. The test mission indicated that airborne ballistic camera tracking systems are feasible.

  6. Airborne concentrations of peanut protein.

    PubMed

    Johnson, Rodney M; Barnes, Charles S

    2013-01-01

    Food allergy to peanut is a significant health problem, and there are reported allergic reactions to peanuts despite not eating or having physical contact with peanuts. It is presumed that an allergic reaction may have occurred from inhalation of airborne peanut allergens. The purpose of this study was to detect the possible concentrations of airborne peanut proteins for various preparations and during specific activities. Separate Ara h 1 and Ara h 2 monoclonal enzyme-linked immunosorbent assays and a polyclonal sandwich enzyme immunoassay for peanuts were used to detect the amount of airborne peanut protein collected using a Spincon Omni 3000 air collector (Sceptor Industries, Inc., Kansas City, MO) under different peanut preparation methods and situations. Air samples were measured for multiple peanut preparations and scenarios. Detectable amounts of airborne peanut protein were measured using a whole peanut immunoassay when removing the shells of roasted peanut. No airborne peanut allergen (Ara h 1 or Ara h 2) or whole peanut protein above the LLD was measured in any of the other peanut preparation collections. Ara h 1, Ara h 2, and polyclonal peanut proteins were detected from water used to boil peanuts. Small amounts of airborne peanut protein were detected in the scenario of removing shells from roasted peanuts; however, Ara h 1 and Ara h 2 proteins were unable to be consistently detected. Although airborne peanut proteins were detected, the concentration of airborne peanut protein that is necessary to elicit a clinical allergic reaction is unknown. PMID:23406937

  7. Microparticles Mediate Hepatic Ischemia-Reperfusion Injury and Are the Targets of Diannexin (ASP8597)

    PubMed Central

    Wong, Heng Jian; Croft, Kevin; Mori, Trevor; Farrell, Geoffrey C.

    2014-01-01

    Background & Aims Ischemia–reperfusion injury (IRI) can cause hepatic failure after liver surgery or transplantation. IRI causes oxidative stress, which injures sinusoidal endothelial cells (SECs), leading to recruitment and activation of Kupffer cells, platelets and microcirculatory impairment. We investigated whether injured SECs and other cell types release microparticles during post-ischemic reperfusion, and whether such microparticles have pro-inflammatory, platelet-activating and pro-injurious effects that could contribute to IRI pathogenesis. Methods C57BL6 mice underwent 60 min of partial hepatic ischemia followed by 15 min–24 hrs of reperfusion. We collected blood and liver samples, isolated circulating microparticles, and determined protein and lipid content. To establish mechanism for microparticle production, we subjected murine primary hepatocytes to hypoxia-reoxygenation. Because microparticles express everted phosphatidylserine residues that are the target of annexin V, we analyzed the effects of an annexin V-homodimer (Diannexin or ASP8597) on post-ischemia microparticle production and function. Results Microparticles were detected in the circulation 15–30 min after post-ischemic reperfusion, and contained markers of SECs, platelets, natural killer T cells, and CD8+ cells; 4 hrs later, they contained markers of macrophages. Microparticles contained F2-isoprostanes, indicating oxidative damage to membrane lipids. Injection of mice with TNF-α increased microparticle formation, whereas Diannexin substantially reduced microparticle release and prevented IRI. Hypoxia-re-oxygenation generated microparticles from primary hepatocytes by processes that involved oxidative stress. Exposing cultured hepatocytes to preparations of microparticles isolated from the circulation during IRI caused injury involving mitochondrial membrane permeability transition. Microparticles also activated platelets and induced neutrophil migration in vitro. The inflammatory

  8. Airborne signals of communication in sagebrush: a pharmacological approach

    PubMed Central

    Shiojiri, Kaori; Ishizaki, Satomi; Ozawa, Rika; Karban, Richard

    2015-01-01

    When plants receive volatiles from a damaged plant, the receivers become more resistant to herbivory. This phenomenon has been reported in many plant species and called plant-plant communication. Lab experiments have suggested that several compounds may be functioning as airborne signals. The objective of this study is to identify potential airborne signals used in communication between sagebrush (Artemisia tridentata) individuals in the field. We collected volatiles of one branch from each of 99 sagebrush individual plants. Eighteen different volatiles were detected by GC-MS analysis. Among these, 4 compounds; 1.8-cineol, β-caryophyllene, α-pinene and borneol, were investigated as signals of communication under natural conditions. The branches which received either 1,8-cineol or β-caryophyllene tended to get less damage than controls. These results suggested that 1,8-cineol and β-caryophyllene should be considered further as possible candidates for generalized airborne signals in sagebrush. PMID:26418970

  9. Cellular uptake of Nigella sativa oil-PLGA microparticle by PC-12 cell line.

    PubMed

    Doolaanea, Abd Almonem; Mansor, Nur 'Izzati; Mohd Nor, Nurul Hafizah; Mohamed, Farahidah

    2014-01-01

    The aim of this study is to investigate the cell uptake of Nigella sativa oil (NSO)-PLGA microparticle by neuron-like PC-12 cells in comparison to surfactants; hydrophilic (Tween 80 & Triton X100) and hydrophobic (Span 80). Solvent evaporation was used to precisely control the size, zeta potential and morphology of the particle. The results revealed varying efficiencies of the cell uptake by PC-12 cells, which may be partially attributed to the surface hydrophobicity of the microparticles. Interestingly, the uptake efficiency of PC-12 cells was higher with the more hydrophilic microparticle. NSO microparticle showed evidence of being preferably internalised by mitotic cells. Tween 80 microparticle showed the highest cell uptake efficiency with a concentration-dependent pattern suggesting its use as uptake enhancer for non-scavenging cells. In conclusion, PC-12 cells can take up NSO-PLGA microparticle which may have potential in the treatment of neurodegenerative disease. PMID:24697178

  10. Reduction in microparticle adsorption using a lateral interconnection method in a PDMS-based microfluidic device.

    PubMed

    Lee, Do-Hyun; Park, Je-Kyun

    2013-12-01

    Microparticle adsorption on microchannel walls occurs frequently due to nonspecific interactions, decreasing operational performance in pressure-driven microfluidic systems. However, it is essential for delicate manipulation of microparticles or cells to maintain smooth fluid traffic. Here, we report a novel microparticle injection technique, which prevents particle loss, assisted by sample injection along the direction of fluid flow. Sample fluids, including microparticles, mammalian (U937), and green algae (Chlorella vulgaris) cells, were injected directly via a through hole drilled in the lateral direction, resulting in a significant reduction in microparticle attachment. For digital microfluidic application, the proposed regime achieved a twofold enhancement of single-cell encapsulation compared to the conventional encapsulation rate, based on a Poisson distribution, by reducing the number of empty droplets. This novel interconnection method can be straightforwardly integrated as a microparticle or cell injection component in integrated microfluidic systems.

  11. Pharmacological modulation of procoagulant microparticles improves haemodynamic dysfunction during septic shock in rats.

    PubMed

    Boisramé-Helms, Julie; Delabranche, Xavier; Degirmenci, Su-Emmanuelle; Zobairi, Fatiha; Berger, Asael; Meyer, Grégory; Burban, Mélanie; Mostefai, Hadj-Ahmed; Levy, Bruno; Toti, Florence; Meziani, Ferhat

    2014-01-01

    Circulating microparticles play a pro-inflammatory and procoagulant detrimental role in the vascular dysfunction of septic shock. It was the objective of this study to investigate mechanisms by which a pharmacological modulation of microparticles could affect vascular dysfunction in a rat model of septic shock. Septic or sham rats were treated by activated protein C (aPC) and resuscitated during 4 hours. Their microparticles were harvested and inoculated to another set of healthy recipient rats. Haemodynamic parameters were monitored, circulating total procoagulant microparticles assessed by prothrombinase assay, and their cell origin characterised. Mesenteric resistance arteries, aorta and heart were harvested for western blotting analysis. We found that a) the amount and phenotype of circulating microparticles were altered in septic rats with an enhanced endothelial, leucocyte and platelet contribution; b) aPC treatment significantly reduced the generation of leucocyte microparticles and norepinephrine requirements to reach the mean arterial pressure target in septic rats; c) Microparticles from untreated septic rats, but not from aPC-treated ones, significantly reduced the healthy recipients' mean arterial pressure; d) Microparticle thromboxane content and aPC activity were significantly increased in aPC-treated septic rats. In inoculated naïve recipients, microparticles from aPC-treated septic rats prompted reduced NF-κB and cyclooxygenase-2 arterial activation, blunted the generation of pro-inflammatory iNOS and secondarily increased platelet and endothelial microparticles. In conclusion, in this septic shock model, increased circulating levels of procoagulant microparticles led to negative haemodynamic outcomes. Pharmacological treatment by aPC modified the cell origin and levels of circulating microparticles, thereby limiting vascular inflammation and favouring haemodynamic improvement.

  12. Effect of solvent composition during preparations on the characteristics of enoxacin microparticles.

    PubMed

    Yang, Q; Reams, R; Owusu-Ababio, G

    1999-06-01

    We have studied the effect of the solvent system during preparation on the morphology, encapsulation efficiency, and release characteristics of enoxacin microparticles intended for localized delivery to the bone for the treatment of bone infections. Microparticles of enoxacin were formulated using poly(glycolic acid-co-DL-lactic acid) (PGLA) of different viscosity grades by the solvent-evaporation technique. Microparticles prepared with pure dichloromethane had smoother surfaces and less tendency to aggregate than microparticles prepared with dichloromethane-acetone solvent mixtures, which had porous surfaces. Approximately 65% of the microparticles prepared with pure dichloromethane were < 125 microm in diameter compared with 16% (approx.) of microparticles prepared with dichloromethane-acetone mixtures. Increasing the proportion of acetone from dichloromethane-acetone, 10:0, to dichloromethane-acetone, 1:1, resulted in an increase in encapsulation efficiency from 25 to 37%, and an increase in the yield of microparticles harvested from 39 to 51%. Although a further increase in the amount of acetone to dichloromethane-acetone, 1:9, had no significant effect on the yield, aggregation, or fraction of microparticles below 125 microm in diameter, the encapsulation efficiency increased to 56%. Approximately 55% of enoxacin was released in 24 h for microparticles prepared with dichloromethane-acetone, 1:9, compared with 100% release in 10h and 2h for microparticles of the same size range prepared with dichloromethane-acetone, 1:1, and dichloromethane-acetone, 10:0, respectively. The results suggest that the composition of the dichloromethane-acetone solvent system significantly influences the encapsulation efficiency and the rate of release of enoxacin from microparticles. This is important for the formulation of sustained-release enoxacin microparticles for the localized treatment of osteomyelitis.

  13. A simple microfluidic dispenser for single-microparticle and cell samples

    PubMed Central

    Kasukurti, A.; Eggleton, C.D.; Desai, S.A.; Disharoon, D. I.; Marr, D.W.M.

    2014-01-01

    Non-destructive isolation of single-cells has become an important need for many biology research laboratories; however, there is a lack of easily employed and inexpensive tools. Here, we present a single-particle sample delivery approach fabricated from simple, economical components that may address this need. In this, we employ unique flow and timing strategies to bridge the significant force and length scale differences inherent in transitioning from single particle isolation to delivery. Demonstrating this approach, we use an optical trap to isolate individual microparticles and red blood cells that are dispensed within separate 50 µl droplets off a microfluidic chip for collection into microscope slides or microtiter plates. PMID:25316326

  14. Modeling for Airborne Contamination

    SciTech Connect

    F.R. Faillace; Y. Yuan

    2000-08-31

    The objective of Modeling for Airborne Contamination (referred to from now on as ''this report'') is to provide a documented methodology, along with supporting information, for estimating the release, transport, and assessment of dose to workers from airborne radioactive contaminants within the Monitored Geologic Repository (MGR) subsurface during the pre-closure period. Specifically, this report provides engineers and scientists with methodologies for estimating how concentrations of contaminants might be distributed in the air and on the drift surfaces if released from waste packages inside the repository. This report also provides dose conversion factors for inhalation, air submersion, and ground exposure pathways used to derive doses to potentially exposed subsurface workers. The scope of this report is limited to radiological contaminants (particulate, volatile and gaseous) resulting from waste package leaks (if any) and surface contamination and their transport processes. Neutron activation of air, dust in the air and the rock walls of the drift during the preclosure time is not considered within the scope of this report. Any neutrons causing such activation are not themselves considered to be ''contaminants'' released from the waste package. This report: (1) Documents mathematical models and model parameters for evaluating airborne contaminant transport within the MGR subsurface; and (2) Provides tables of dose conversion factors for inhalation, air submersion, and ground exposure pathways for important radionuclides. The dose conversion factors for air submersion and ground exposure pathways are further limited to drift diameters of 7.62 m and 5.5 m, corresponding to the main and emplacement drifts, respectively. If the final repository design significantly deviates from these drift dimensions, the results in this report may require revision. The dose conversion factors are further derived by using concrete of sufficient thickness to simulate the drift

  15. Performance Basis for Airborne Separation

    NASA Technical Reports Server (NTRS)

    Wing, David J.

    2008-01-01

    Emerging applications of Airborne Separation Assistance System (ASAS) technologies make possible new and powerful methods in Air Traffic Management (ATM) that may significantly improve the system-level performance of operations in the future ATM system. These applications typically involve the aircraft managing certain components of its Four Dimensional (4D) trajectory within the degrees of freedom defined by a set of operational constraints negotiated with the Air Navigation Service Provider. It is hypothesized that reliable individual performance by many aircraft will translate into higher total system-level performance. To actually realize this improvement, the new capabilities must be attracted to high demand and complexity regions where high ATM performance is critical. Operational approval for use in such environments will require participating aircraft to be certified to rigorous and appropriate performance standards. Currently, no formal basis exists for defining these standards. This paper provides a context for defining the performance basis for 4D-ASAS operations. The trajectory constraints to be met by the aircraft are defined, categorized, and assessed for performance requirements. A proposed extension of the existing Required Navigation Performance (RNP) construct into a dynamic standard (Dynamic RNP) is outlined. Sample data is presented from an ongoing high-fidelity batch simulation series that is characterizing the performance of an advanced 4D-ASAS application. Data of this type will contribute to the evaluation and validation of the proposed performance basis.

  16. Fabrication of pseudo-ceramide-based lipid microparticles for recovery of skin barrier function.

    PubMed

    Kim, Do-Hoon; Park, Woo Ram; Kim, Jeong Hwan; Cho, Eun Chul; An, Eun Jung; Kim, Jin-Woong; Oh, Seong-Geun

    2012-06-01

    The recovery of skin barrier functions was investigated with pseudo-ceramide-based lipid microparticles. The microparticles were prepared by using a fluid bed technique where lipid components (a pseudo-ceramide, cholesterol and a fatty acid) were coated on a sugar seed, and a polymer was subsequently coated on the lipid microparticles. The microparticles contained large amount of pseudo-ceramide, and the pseudo-ceramide was in the form of lamellar structures mixed with other lipid components. In addition, the microparticles were stably dispersed in aqueous media or emulsion systems without any disruption of the microparticles' structures, thereby supplying sufficient amount of the pseudo-ceramide to skins for improving skin barrier functions such as preventing water loss. Such a role of the microparticles was proven by evaluating in vivo the efficacy of the lipid microparticles in reducing a trans-epidermal water loss (TEWL) of impaired murine skins. As a result, the novel pseudo-ceramide-based lipid microparticles for barrier recovery may potentially be applied in the field of dermatology, cosmetics and pharmaceuticals.

  17. On the origin of microparticles: From “platelet dust” to mediators of intercellular communication

    PubMed Central

    Hargett, Leslie A.; Bauer, Natalie N.

    2013-01-01

    Microparticles are submicron vesicles shed from a variety of cells. Peter Wolf first identified microparticles in the midst of ongoing blood coagulation research in 1967 as a product of platelets. He termed them platelet dust. Although initially thought to be useless cellular trash, decades of research focused on the tiny vesicles have defined their roles as participators in coagulation, cellular signaling, vascular injury, and homeostasis. The purpose of this review is to highlight the science leading up to the discovery of microparticles, feature discoveries made by key contributors to the field of microparticle research, and discuss their positive and negative impact on the pulmonary circulation. PMID:24015332

  18. On the origin of microparticles: From "platelet dust" to mediators of intercellular communication.

    PubMed

    Hargett, Leslie A; Bauer, Natalie N

    2013-04-01

    Microparticles are submicron vesicles shed from a variety of cells. Peter Wolf first identified microparticles in the midst of ongoing blood coagulation research in 1967 as a product of platelets. He termed them platelet dust. Although initially thought to be useless cellular trash, decades of research focused on the tiny vesicles have defined their roles as participators in coagulation, cellular signaling, vascular injury, and homeostasis. The purpose of this review is to highlight the science leading up to the discovery of microparticles, feature discoveries made by key contributors to the field of microparticle research, and discuss their positive and negative impact on the pulmonary circulation.

  19. pH-Sensitive Microparticles with Matrix-Dispersed Active Agent

    NASA Technical Reports Server (NTRS)

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

    2014-01-01

    Methods to produce pH-sensitive microparticles that have an active agent dispersed in a polymer matrix have certain advantages over microcapsules with an active agent encapsulated in an interior compartment/core inside of a polymer wall. The current invention relates to pH-sensitive microparticles that have a corrosion-detecting or corrosion-inhibiting active agent or active agents dispersed within a polymer matrix of the microparticles. The pH-sensitive microparticles can be used in various coating compositions on metal objects for corrosion detecting and/or inhibiting.

  20. Preparation, In Vitro Characterization, and In Vivo Pharmacokinetic Evaluation of Respirable Porous Microparticles Containing Rifampicin

    PubMed Central

    Kundawala, Aliasgar; Patel, Vishnu; Patel, Harsha; Choudhary, Dhaglaram

    2014-01-01

    Abstract This study aimed to prepare and evaluate rifampicin microparticles for the lung delivery of rifampicin as respirable powder. The microparticles were prepared using chitosan by the spray-drying method and evaluated for aerodynamic properties and pulmonary drug absorption. To control the drug release, tripoly-phosphate in different concentrations 0.6, 0.9, 1.2, and 1.5 was employed to get a sustained drug release profile. The microparticles were evaluated for drug loading, % entrapment efficiency, tapped density, morphological characteristics, and in vitro drug release studies. Aerosol properties were determined using the Andersen cascade impactor. Porous microparticles with particle sizes (d0.5) less than 10 μm were obtained. The entrapment of rifampicin in microparticles was up to 72%. In vitro drug release suggested that the crosslinked microparticles showed sustained release for more than 12 hrs. The drug release rate was found to be decreased as the TPP concentration was increased. The microparticles showed a fine particle fraction in the range of 55–63% with mass median aerodynamic diameter (MMAD) values below 3 μm. The in vivo pulmonary absorption of the chitosan microparticles suggested a sustained drug release profile up to 72 hrs with an elimination rate of 0.010 per hr. The studies revealed that the spray-dried porous microparticles have suitable properties to be used as respirable powder in rifampicin delivery to the lungs. PMID:25853075

  1. Stable cationic microparticles for enhanced model antigen delivery to dendritic cells.

    PubMed

    Wischke, Christian; Borchert, Hans-Hubert; Zimmermann, Julian; Siebenbrodt, Ingo; Lorenzen, Dirk R

    2006-09-12

    The objectives of this work were (i) to prepare physically stable cationic microparticles and (ii) to study the impact of the surface properties on microparticle phagocytosis and the phenotype of dendritic cells (DC). Protein loaded biodegradable microparticles from poly(lactic-co-glycolic acid) [PLGA] were produced in a micromixer-based w/o/w solvent evaporation procedure. Anionic particles were obtained by using polyvinyl alcohol (PVA) as stabilizing agent; for cationic surfaces cetyltrimethylammonium bromide (CTAB) and chitosan/PVA or DEAE-dextran/PVA blends were evaluated. In phagocytosis studies human monocytes and monocyte-derived DC were incubated with microparticles and analysed by flow cytometry. While CTAB modified microparticles lost their positive charge and aggregated due to CTAB desorption from the particle surface, the modification with chitosan and DEAE-dextran resulted in stable microparticles without cell toxicity. Due to a very low endotoxin content, phagocytosis of anionic and cationic microparticles did not induce an upregulation of maturation-associated surface markers on DC. DEAE-dextran modified microparticles showed an enhanced model protein delivery into phagocytic cells. Overall, PLGA microparticles are suitable vehicles for protein delivery to DC, which might be used for DC-based cell therapies.

  2. Fabrication of pseudo-ceramide-based lipid microparticles for recovery of skin barrier function.

    PubMed

    Kim, Do-Hoon; Park, Woo Ram; Kim, Jeong Hwan; Cho, Eun Chul; An, Eun Jung; Kim, Jin-Woong; Oh, Seong-Geun

    2012-06-01

    The recovery of skin barrier functions was investigated with pseudo-ceramide-based lipid microparticles. The microparticles were prepared by using a fluid bed technique where lipid components (a pseudo-ceramide, cholesterol and a fatty acid) were coated on a sugar seed, and a polymer was subsequently coated on the lipid microparticles. The microparticles contained large amount of pseudo-ceramide, and the pseudo-ceramide was in the form of lamellar structures mixed with other lipid components. In addition, the microparticles were stably dispersed in aqueous media or emulsion systems without any disruption of the microparticles' structures, thereby supplying sufficient amount of the pseudo-ceramide to skins for improving skin barrier functions such as preventing water loss. Such a role of the microparticles was proven by evaluating in vivo the efficacy of the lipid microparticles in reducing a trans-epidermal water loss (TEWL) of impaired murine skins. As a result, the novel pseudo-ceramide-based lipid microparticles for barrier recovery may potentially be applied in the field of dermatology, cosmetics and pharmaceuticals. PMID:22361356

  3. Association of circulating endothelial microparticles with cardiometabolic risk factors in the Framingham Heart Study

    PubMed Central

    Amabile, Nicolas; Cheng, Susan; Renard, Jean Marie; Larson, Martin G.; Ghorbani, Anahita; McCabe, Elizabeth; Griffin, Gabriel; Guerin, Coralie; Ho, Jennifer E.; Shaw, Stanley Y.; Cohen, Kenneth S.; Vasan, Ramachandran S.; Tedgui, Alain; Boulanger, Chantal M.; Wang, Thomas J.

    2014-01-01

    Objective To examine the relation of endothelial microparticles (EMPs) with cardiometabolic risk in the community. Background Circulating EMPs are small membrane vesicles released after endothelial cell injury. Endothelial microparticles are reportedly increased among individuals with a high burden of cardiovascular risk factors. However, prior investigations have been limited to small, highly selected samples. Methods We studied 844 individuals without a history of cardiovascular disease in the Framingham Offspring cohort (mean age 66 ± 9 years, 57% women). We used standardized flow cytometry methods to identify and quantify circulating CD144+ and CD31+/CD41− EMPs. We then used multivariable regression analyses to investigate the relations of EMP phenotypes with cardiovascular and metabolic risk factors. Results In multivariable analyses, the following cardiovascular risk factors were associated with one or more of the circulating EMP populations: hypertension (P = 0.025 for CD144+,), elevated triglycerides (P = 0.002 for CD144+, P < 0.0001 for CD31+/CD41−), and metabolic syndrome (P < 0.0001 for CD144+,). Overall, each tertile increase in the Framingham risk score corresponded to a 9% increase in log-CD31+/CD41− EMPs (P = 0.022). Furthermore, the presence of hypertriglyceridaemic waist status was associated with 38% higher levels of CD144+ EMPs (P < 0.0001) and 46% higher levels of CD31+/CD41− EMPs (P < 0.0001). Conclusion In a large community-based sample, circulating EMP levels were associated with the presence of cardiometabolic risk factors, particularly dyslipidaemia. These data underscore the potential influence of high-risk metabolic profiles on endothelial integrity. PMID:24742886

  4. Influence of matrix composition of shape of cracking catalyst microparticles

    SciTech Connect

    Klaptsov, V.F.; Nefedov, B.K.; Khlebnikova, M.A.; Maslova, A.A.

    1988-09-01

    The best cracking catalysts in terms of service characteristics are those with particles in the shape of microbeads (microspheres) formed by spray drying. This article presents data on the influence of composition of the matrix, prepared from a mixture of pseudoboehmite and a natural component, on the shape of microparticles of series KN cracking catalysts. Two grades of a kaolinite clay from Troshkovo deposit were used a natural component. Pelletized specimens were used in determining the crushing strength of the catalysts. The results from these studies show that in order to prepare catalysts with spherical microparticles and high strength, it is necessary to use a semisynthetic matrix with pseudoboehmite not greater than 25% and alkaline-earth metals bringing the pH to a level above 7.5-8.

  5. Refractory absorber/emitter using monolayer of ceramic microparticles

    NASA Astrophysics Data System (ADS)

    Dyachenko, P. N.; do Rosário, J. J.; Leib, E. W.; Petrov, A. Y.; Störmer, M.; Weller, H.; Vossmeyer, T.; Schneider, G. A.; Eich, M.

    2016-04-01

    We present a self-assembled refractory absorber/emitter without the necessity to structure the metallic surface itself, still retaining the feature of tailored optical properties for visible light emission and thermophotovoltaic (TPV) applications. We have demonstrated theoretically and experimentally that monolayers of zirconium dioxide (ZrO2) microparticles on a tungsten layer can be used as large area, efficient and thermally stable selective absorbers/emitters. The band edge of the absorption is based on critically coupled microsphere resonances. It can be tuned from visible to near-infrared range by varying the diameter of the microparticles. We demonstrated the optical functionality of the structure after annealing up to temperatures of 1000°C under vacuum conditions. In particular it opens up the route towards high efficiency TPV systems with emission matched to the photovoltaic cell.

  6. Micro-Particles as Electrostatic Probes for Plasma Sheath Diagnostic

    SciTech Connect

    Wolter, Matthias; Haass, Moritz; Ockenga, Taalke; Kersten, Holger; Blazec, Joseph; Basner, Ralf

    2008-09-07

    An interesting aspect in the research of complex (dusty) plasmas is the experimental study of the interaction of micro-particles of different sizes with the surrounding plasma for diagnostic purpose. In the plasma micro-disperse particles are negatively charged and confined in the sheath. The particles are trapped by an equilibrium of gravity, electric field force and ion drag force. From the behavior, local electric fields can be determined, e.g. particles are used as electrostatic probes. In combination with additional measurements of the plasma parameters with Langmuir probes and thermal probes as well as by comparison with an analytical sheath model, the structure of the sheath can be described. In the present work we focus on the behavior of micro-particles of different sizes and several plasma parameters e.g. the gas pressure and the rf-power.

  7. Self-organized internal architectures of chiral micro-particles

    SciTech Connect

    Provenzano, Clementina; Mazzulla, Alfredo; Desiderio, Giovanni; Pagliusi, Pasquale; De Santo, Maria P.; Cipparrone, Gabriella; Perrotta, Ida

    2014-02-01

    The internal architecture of polymeric self-assembled chiral micro-particles is studied by exploring the effect of the chirality, of the particle sizes, and of the interface/surface properties in the ordering of the helicoidal planes. The experimental investigations, performed by means of different microscopy techniques, show that the polymeric beads, resulting from light induced polymerization of cholesteric liquid crystal droplets, preserve both the spherical shape and the internal self-organized structures. The method used to create the micro-particles with controlled internal chiral architectures presents great flexibility providing several advantages connected to the acquired optical and photonics capabilities and allowing to envisage novel strategies for the development of chiral colloidal systems and materials.

  8. Foam injection molding of elastomers with iron microparticles

    NASA Astrophysics Data System (ADS)

    Volpe, Valentina; D'Auria, Marco; Sorrentino, Luigi; Davino, Daniele; Pantani, Roberto

    2015-12-01

    In this work, a preliminary study of foam injection molding of a thermoplastic elastomer, Engage 8445, and its microcomposite loaded with iron particles was carried out, in order to evaluate the effect of the iron microparticles on the foaming process. In particular, reinforced samples have been prepared by using nanoparticles at 2% by volume. Nitrogen has been used as physical blowing agent. Foamed specimens consisting of neat and filled elastomer were characterized by density measurements and morphological analysis. While neat Engage has shown a well developed cellular morphology far from the injection point, the addition of iron microparticles considerably increased the homogeneity of the cellular morphology. Engage/iron foamed samples exhibited a reduction in density greater than 32%, with a good and homogeneous cellular morphology, both in the transition and in the core zones, starting from small distances from the injection point.

  9. Multiphase ferrofluid flows for micro-particle sorting

    NASA Astrophysics Data System (ADS)

    Zhou, Ran; Wang, Cheng

    2015-11-01

    Utilizing negative magnetophoresis, ferrofluids have demonstrated great potential for sorting nonmagnetic micro-particles by size. Most of the existing techniques use single phase ferrofluids by pushing micro-particles to channel walls; the sorting speed is thus hindered. We demonstrate a novel sorting strategy by co-flowing a ferrofluid and a non-magnetic fluid in microchannels. Due to the magnetic force, the particles migrate across the ferrofluid stream at size-dependent velocities as they travel downstream. The laminar interface between the two fluids functions as a virtual boundary to accumulate particles, resulting in effective separation of particles. A stable and sharp interface is important to the success of this sorting technique. We investigate several factors that affect sorting efficiency, including magnetic field, susceptibility difference of the fluids, flow velocity, and channel geometry.

  10. Principles of transverse flow fractionation of microparticles in superhydrophobic channels.

    PubMed

    Asmolov, Evgeny S; Dubov, Alexander L; Nizkaya, Tatiana V; Kuehne, Alexander J C; Vinogradova, Olga I

    2015-07-01

    We propose a concept of fractionation of micron-sized particles in a microfluidic device with a bottom wall decorated by superhydrophobic stripes. The stripes are oriented at an angle α to the direction of a driving force, G, which generally includes an applied pressure gradient and gravity. Separation relies on the initial sedimentation of particles under gravity in the main forward flow, and their subsequent lateral deflection near a superhydrophobic wall due to generation of a secondary flow transverse to G. We provide some theoretical arguments allowing us to quantify the transverse displacement of particles in the microfluidic channel, and confirm the validity of theoretical predictions in test experiments with monodisperse fractions of microparticles. Our results can guide the design of superhydrophobic microfluidic devices for efficient sorting of microparticles with a relatively small difference in size and density. PMID:26016651

  11. Airborne agent concentration analysis

    DOEpatents

    Gelbard, Fred

    2004-02-03

    A method and system for inferring airborne contaminant concentrations in rooms without contaminant sensors, based on data collected by contaminant sensors in other rooms of a building, using known airflow interconnectivity data. The method solves a least squares problem that minimizes the difference between measured and predicted contaminant sensor concentrations with respect to an unknown contaminant release time. Solutions are constrained to providing non-negative initial contaminant concentrations in all rooms. The method can be used to identify a near-optimal distribution of sensors within the building, when then number of available sensors is less than the total number of rooms. This is achieved by having a system-sensor matrix that is non-singular, and by selecting that distribution which yields the lowest condition number of all the distributions considered. The method can predict one or more contaminant initial release points from the collected data.

  12. Airborne Wind Turbine

    SciTech Connect

    2010-09-01

    Broad Funding Opportunity Announcement Project: Makani Power is developing an Airborne Wind Turbine (AWT) that eliminates 90% of the mass of a conventional wind turbine and accesses a stronger, more consistent wind at altitudes of near 1,000 feet. At these altitudes, 85% of the country can offer viable wind resources compared to only 15% accessible with current technology. Additionally, the Makani Power wing can be economically deployed in deep offshore waters, opening up a resource which is 4 times greater than the entire U.S. electrical generation capacity. Makani Power has demonstrated the core technology, including autonomous launch, land, and power generation with an 8 meter wingspan, 20 kW prototype. At commercial scale, Makani Power aims to develop a 600 kW, 28 meter wingspan product capable of delivering energy at an unsubsidized cost competitive with coal, the current benchmark for low-cost power.

  13. Incorporation of iodine in polymeric microparticles and emulsions

    NASA Astrophysics Data System (ADS)

    Kolontaeva, Olga A.; Khokhlova, Anastasia R.; Markina, Natalia E.; Markin, Alexey V.; Burmistrova, Natalia A.

    2016-04-01

    Application of different methods for formation of microcontainers containing iodine is proposed in this paper. Two types of microcontainers: microemulsions and microparticles have been investigated, conditions and methods for obtaining microcontainers were optimized. Microparticles were formed by layer-by-layer method with cores of calcium carbonate (CaCO3) as templates. Incorporation of complexes of iodine with polymers (chitosan, starch, polyvinyl alcohol) into core, shell and hollow capsules was investigated and loadings of microparticles with iodine were estimated. It was found that the complex of iodine with chitosan adsorbed at CaCO3 core is the most stable under physiological conditions and its value of loading can be 450 μg of I2 per 1 g of CaCO3. Moreover, chitosan was chosen as a ligand because of its biocompatibility and biodegradability as well as very low toxicity while its complex with iodine is very stable. A small amount of microparticles containing a iodine-chitosan complex can be used for prolonged release of iodine in the human body since iodine daily intake for adults is around 100 μg. "Oil-in-water" emulsions were prepared by ultrasonication of iodinated oils (sunflower and linseed) with sodium laurilsulfate (SLS) as surfactant solution. At optimal conditions, the homogenous emulsions remained stable for weeks, with total content of iodine in such emulsion being up to 1% (w/w). The oil:SLS ratio was equal to 1:10 (w/w), optimal duration and power of ultrasound exposure were 1.5 min and 7 W, correspondingly. Favorable application of iodized linseed oil for emulsion preparation with suitable oil microdroplets size was proved.

  14. Alginate-based hybrid aerogel microparticles for mucosal drug delivery.

    PubMed

    Gonçalves, V S S; Gurikov, P; Poejo, J; Matias, A A; Heinrich, S; Duarte, C M M; Smirnova, I

    2016-10-01

    The application of biopolymer aerogels as drug delivery systems (DDS) has gained increased interest during the last decade since these structures have large surface area and accessible pores allowing for high drug loadings. Being biocompatible, biodegradable and presenting low toxicity, polysaccharide-based aerogels are an attractive carrier to be applied in pharmaceutical industry. Moreover, some polysaccharides (e.g. alginate and chitosan) present mucoadhesive properties, an important feature for mucosal drug delivery. This feature allows to extend the contact of DDS with biological membranes, thereby increasing the absorption of drugs through the mucosa. Alginate-based hybrid aerogels in the form of microparticles (<50μm) were investigated in this work as carriers for mucosal administration of drugs. Low methoxyl pectin and κ-carrageenan were co-gelled with alginate and further dried with supercritical CO2 (sc-CO2). Spherical mesoporous aerogel microparticles were obtained for alginate, hybrid alginate/pectin and alginate/κ-carrageenan aerogels, presenting high specific surface area (370-548m(2)g(-1)) and mucoadhesive properties. The microparticles were loaded with ketoprofen via adsorption from its solution in sc-CO2, and with quercetin via supercritical anti-solvent precipitation. Loading of ketoprofen was in the range between 17 and 22wt% whereas quercetin demonstrated loadings of 3.1-5.4wt%. Both the drugs were present in amorphous state. Loading procedure allowed the preservation of antioxidant activity of quercetin. Release of both drugs from alginate/κ-carrageenan aerogel was slightly faster compared to alginate/pectin. The results indicate that alginate-based aerogel microparticles can be viewed as promising matrices for mucosal drug delivery applications.

  15. Microfluidic device for the assembly and transport of microparticles

    DOEpatents

    James, Conrad D.; Kumar, Anil; Khusid, Boris; Acrivos, Andreas

    2010-06-29

    A microfluidic device comprising independently addressable arrays of interdigitated electrodes can be used to assembly and transport large-scale microparticle structures. The device and method uses collective phenomena in a negatively polarized suspension exposed to a high-gradient strong ac electric field to assemble the particles into predetermined locations and then transport them collectively to a work area for final assembly by sequentially energizing the electrode arrays.

  16. Optical coherence tomography-based micro-particle image velocimetry.

    PubMed

    Mujat, Mircea; Ferguson, R Daniel; Iftimia, Nicusor; Hammer, Daniel X; Nedyalkov, Ivaylo; Wosnik, Martin; Legner, Hartmut

    2013-11-15

    We present a new application of optical coherence tomography (OCT), widely used in biomedical imaging, to flow analysis in near-wall hydrodynamics for marine research. This unique capability, called OCT micro-particle image velocimetry, provides a high-resolution view of microscopic flow phenomena and measurement of flow statistics within the first millimeter of a boundary layer. The technique is demonstrated in a small flow cuvette and in a water tunnel.

  17. Alginate-based hybrid aerogel microparticles for mucosal drug delivery.

    PubMed

    Gonçalves, V S S; Gurikov, P; Poejo, J; Matias, A A; Heinrich, S; Duarte, C M M; Smirnova, I

    2016-10-01

    The application of biopolymer aerogels as drug delivery systems (DDS) has gained increased interest during the last decade since these structures have large surface area and accessible pores allowing for high drug loadings. Being biocompatible, biodegradable and presenting low toxicity, polysaccharide-based aerogels are an attractive carrier to be applied in pharmaceutical industry. Moreover, some polysaccharides (e.g. alginate and chitosan) present mucoadhesive properties, an important feature for mucosal drug delivery. This feature allows to extend the contact of DDS with biological membranes, thereby increasing the absorption of drugs through the mucosa. Alginate-based hybrid aerogels in the form of microparticles (<50μm) were investigated in this work as carriers for mucosal administration of drugs. Low methoxyl pectin and κ-carrageenan were co-gelled with alginate and further dried with supercritical CO2 (sc-CO2). Spherical mesoporous aerogel microparticles were obtained for alginate, hybrid alginate/pectin and alginate/κ-carrageenan aerogels, presenting high specific surface area (370-548m(2)g(-1)) and mucoadhesive properties. The microparticles were loaded with ketoprofen via adsorption from its solution in sc-CO2, and with quercetin via supercritical anti-solvent precipitation. Loading of ketoprofen was in the range between 17 and 22wt% whereas quercetin demonstrated loadings of 3.1-5.4wt%. Both the drugs were present in amorphous state. Loading procedure allowed the preservation of antioxidant activity of quercetin. Release of both drugs from alginate/κ-carrageenan aerogel was slightly faster compared to alginate/pectin. The results indicate that alginate-based aerogel microparticles can be viewed as promising matrices for mucosal drug delivery applications. PMID:27393563

  18. Airborne Cloud Computing Environment (ACCE)

    NASA Technical Reports Server (NTRS)

    Hardman, Sean; Freeborn, Dana; Crichton, Dan; Law, Emily; Kay-Im, Liz

    2011-01-01

    Airborne Cloud Computing Environment (ACCE) is JPL's internal investment to improve the return on airborne missions. Improve development performance of the data system. Improve return on the captured science data. The investment is to develop a common science data system capability for airborne instruments that encompasses the end-to-end lifecycle covering planning, provisioning of data system capabilities, and support for scientific analysis in order to improve the quality, cost effectiveness, and capabilities to enable new scientific discovery and research in earth observation.

  19. Promoting optofluidic actuation of microparticles with plasmonic nanoparticles

    NASA Astrophysics Data System (ADS)

    Burgin, Julien; Si, Satyabrata; Delville, Marie-Hélène; Delville, Jean-Pierre

    2014-09-01

    The amplitude of optical forces on flowing dielectric microparticles can be actuated by coating them partially with metallic nanospheres and exposing them to laser light within the surface plasmon resonance. Here, optical forces on both pure silica particles and silica-gold raspberries are characterized within an optical chromatography setup by measuring the Stokes drag versus laser beam power. Results are compared to Mie theory predictions for both core dielectric particles and core-shell ones where the shell is described by a continuous dielectricmetal composite of dielectric constant determined from the Maxwell Garnett approach. The nice observed quantitative agreement demonstrates that radiation pressure forces are directly related to the metal concentration present at the microparticle surface and that nano-metallic objects increase the magnitude of optical forces compared to pure dielectric particles of the same overall size, even at very low metal concentration. Behaving as "micro-sized nanoparticles", the benefit of microparticles coated with metallic nanospheres is thus twofold: (i) to enhance optofluidic manipulation and transport at the microscale and (ii) to increase sensing capabilities at the nanoscale, compared to separated pure dielectric particles and single metallic nanosystems.

  20. Engineering nanoscale surface features to sustain microparticle rolling in flow.

    PubMed

    Kalasin, Surachate; Santore, Maria M

    2015-05-26

    Nanoscopic features of channel walls are often engineered to facilitate microfluidic transport, for instance when surface charge enables electro-osmosis or when grooves drive mixing. The dynamic or rolling adhesion of flowing microparticles on a channel wall holds potential to accomplish particle sorting or to selectively transfer reactive species or signals between the wall and flowing particles. Inspired by cell rolling under the direction of adhesion molecules called selectins, we present an engineered platform in which the rolling of flowing microparticles is sustained through the incorporation of entirely synthetic, discrete, nanoscale, attractive features into the nonadhesive (electrostatically repulsive) surface of a flow channel. Focusing on one example or type of nanoscale feature and probing the impact of broad systematic variations in surface feature loading and processing parameters, this study demonstrates how relatively flat, weakly adhesive nanoscale features, positioned with average spacings on the order of tens of nanometers, can produce sustained microparticle rolling. We further demonstrate how the rolling velocity and travel distance depend on flow and surface design. We identify classes of related surfaces that fail to support rolling and present a state space that identifies combinations of surface and processing variables corresponding to transitions between rolling, free particle motion, and arrest. Finally we identify combinations of parameters (surface length scales, particle size, flow rates) where particles can be manipulated with size-selectivity.

  1. Feasibility of Leadless Cardiac Pacing Using Injectable Magnetic Microparticles.

    PubMed

    Rotenberg, Menahem Y; Gabay, Hovav; Etzion, Yoram; Cohen, Smadar

    2016-01-01

    A noninvasive, effective approach for immediate and painless heart pacing would have invaluable implications in several clinical scenarios. Here we present a novel strategy that utilizes the well-known mechano-electric feedback of the heart to evoke cardiac pacing, while relying on magnetic microparticles as leadless mechanical stimulators. We demonstrate that after localizing intravenously-injected magnetic microparticles in the right ventricular cavity using an external electromagnet, the application of magnetic pulses generates mechanical stimulation that provokes ventricular overdrive pacing in the rat heart. This temporary pacing consistently managed to revert drug-induced bradycardia, but could only last up to several seconds in the rat model, most likely due to escape of the particles between the applied pulses using our current experimental setting. In a pig model with open chest, MEF-based pacing was induced by banging magnetic particles and has lasted for a longer time. Due to overheating of the electromagnet, we intentionally terminated the experiments after 2 min. Our results demonstrate for the first time the feasibility of external leadless temporary pacing, using injectable magnetic microparticles that are manipulated by an external electromagnet. This new approach can have important utilities in clinical settings in which immediate and painless control of cardiac rhythm is required. PMID:27091192

  2. Feasibility of Leadless Cardiac Pacing Using Injectable Magnetic Microparticles

    PubMed Central

    Rotenberg, Menahem Y.; Gabay, Hovav; Etzion, Yoram; Cohen, Smadar

    2016-01-01

    A noninvasive, effective approach for immediate and painless heart pacing would have invaluable implications in several clinical scenarios. Here we present a novel strategy that utilizes the well-known mechano-electric feedback of the heart to evoke cardiac pacing, while relying on magnetic microparticles as leadless mechanical stimulators. We demonstrate that after localizing intravenously-injected magnetic microparticles in the right ventricular cavity using an external electromagnet, the application of magnetic pulses generates mechanical stimulation that provokes ventricular overdrive pacing in the rat heart. This temporary pacing consistently managed to revert drug-induced bradycardia, but could only last up to several seconds in the rat model, most likely due to escape of the particles between the applied pulses using our current experimental setting. In a pig model with open chest, MEF-based pacing was induced by banging magnetic particles and has lasted for a longer time. Due to overheating of the electromagnet, we intentionally terminated the experiments after 2 min. Our results demonstrate for the first time the feasibility of external leadless temporary pacing, using injectable magnetic microparticles that are manipulated by an external electromagnet. This new approach can have important utilities in clinical settings in which immediate and painless control of cardiac rhythm is required. PMID:27091192

  3. Multiphase ferrofluid flows for micro-particle focusing and separation.

    PubMed

    Zhou, Ran; Wang, Cheng

    2016-05-01

    Ferrofluids have demonstrated great potential for a variety of manipulations of diamagnetic (or non-magnetic) micro-particles/cells in microfluidics, including sorting, focusing, and enriching. By utilizing size dependent magnetophoresis velocity, most of the existing techniques employ single phase ferrofluids to push the particles towards the channel walls. In this work, we demonstrate a novel strategy for focusing and separating diamagnetic micro-particles by using the laminar fluid interface of two co-flowing fluids-a ferrofluid and a non-magnetic fluid. Next to the microfluidic channel, microscale magnets are fabricated to generate strong localized magnetic field gradients and forces. Due to the magnetic force, diamagnetic particles suspended in the ferrofluid phase migrate across the ferrofluid stream at the size-dependent velocities. Because of the low Reynolds number and high Péclet number associated with the flow, the fluid interface is sharp and stable. When the micro-particles migrate to the interface, they are accumulated near the interface, resulting in effective focusing and separation of particles. We investigated several factors that affect the focusing and separation efficiency, including susceptibility of the ferrofluid, distance between the microfluidic channel and microscale magnet, and width of the microfluidic channel. This concept can be extended to multiple fluid interfaces. For example, a complete separation of micro-particles was demonstrated by using a three-stream multiphase flow configuration. PMID:27190567

  4. Floating microparticles based on low density foam powder.

    PubMed

    Streubel, A; Siepmann, J; Bodmeier, R

    2002-07-25

    The aim of this study was to develop a novel multiparticulate gastroretentive drug delivery system and to demonstrate its performance in vitro. Floating microparticles consisting of (i) polypropylene foam powder; (ii) verapamil HCl as model drug; and (iii) Eudragit RS, ethylcellulose (EC) or polymethyl methacrylate (PMMA) as polymers were prepared with an O/W solvent evaporation method. The effect of various formulation and processing parameters on the internal and external particle morphology, drug loading, in vitro floating behavior, in vitro drug release kinetics, particle size distribution and physical state of the incorporated drug was studied. The microparticles were irregular in shape and highly porous. The drug encapsulation efficiency was high and almost independent of the theoretical loading. Encapsulation efficiencies close to 100% could be achieved by varying either the ratio 'amount of ingredients: volume of the organic phase' or the relative amount of polymer. In all cases, good in vitro floating behavior was observed. The release rate increased with increasing drug loading and with decreasing polymer amounts. The type of polymer significantly affected the drug release rate, which increased in the following rank order: PMMAmicroparticles was almost independent of the drug loading, but strongly depended on the amount of polymer. The drug was partly dissolved and partly in the amorphous form distributed throughout the system.

  5. Thulium-170-labeled microparticles for local radiotherapy: preliminary studies.

    PubMed

    Polyak, Andras; Das, Tapas; Chakraborty, Sudipta; Kiraly, Reka; Dabasi, Gabriella; Joba, Robert Peter; Jakab, Csaba; Thuroczy, Julianna; Postenyi, Zita; Haasz, Veronika; Janoki, Gergely; Janoki, Gyozo A; Pillai, Maroor R A; Balogh, Lajos

    2014-10-01

    The present article describes the preparation, characterization, and biological evaluation of Thulium-170 ((170)Tm) [T1/2 = 128.4 days; Eβmax = 968 keV; Eγ = 84 keV (3.26%)] labeled tin oxide microparticles for its possible use in radiation synovectomy (RSV) of medium-sized joints. (170)Tm was produced by irradiation of natural thulium oxide target. 170Tm-labeled microparticles were synthesized with high yield and radionuclidic purity (> 99%) along with excellent in vitro stability by following a simple process. Particle sizes and morphology of the radiolabeled particles were examined by light microscope, dynamic light scattering, and transmission electron microscope and found to be of stable spherical morphology within the range of 1.4-3.2 μm. The preparation was injected into the knee joints of healthy Beagle dogs intraarticularly for biological studies. Serial whole-body and regional images were taken by single-photon-emission computed tomography (SPECT) and SPECT-CT cameras up to 9 months postadministration, which showed very low leakage (< 8% of I.D.) of the instilled particles. The majority of leaked radiocolloid particles were found in inguinal lymph nodes during the 9 months of follow-up. All the animals tolerated the treatment well; the compound did not show any possible radiotoxicological effect. These preliminary studies showed that 170Tm-labeled microparticles could be a promising nontoxic and effective radiopharmaceutical for RSV applications or later local antitumor therapy.

  6. Quality Assurance Program Plan for radionuclide airborne emissions monitoring

    SciTech Connect

    Vance, L.M.

    1993-07-01

    This Quality Assurance Program Plan (QAPP) describes the quality assurance requirements and responsibilities for radioactive airborne emissions measurements activities from regulated stacks are controlled at the Hanford Site. Detailed monitoring requirements apply to stacks exceeding 1% of the standard of 10 mrem annual effective dose equivalent to the maximally exposed individual from operations of the Hanford Site.

  7. Solid lipid microparticles produced by spray congealing: influence of the atomizer on microparticle characteristics and mathematical modeling of the drug release.

    PubMed

    Passerini, Nadia; Qi, Sheng; Albertini, Beatrice; Grassi, Mario; Rodriguez, Lorenzo; Craig, Duncan Q M

    2010-02-01

    The first aim of the work was to evaluate the effect of atomizer design on the properties of solid lipid microparticles produced by spray congealing. Two different air atomizers have been employed: a conventional air pressure nozzle (APN) and a recently developed atomizer (wide pneumatic nozzle, WPN). Milled theophylline and Compritol 888ATO were used to produce microparticles at drug-to-carrier ratios of 10:90, 20:80, and 30:70 using the two atomizers. The results showed that the application of different nozzles had significant impacts on the morphology, encapsulation efficiency, and drug release behavior of the microparticles. In contrast, the characteristics of the atomizer did not influence the physicochemical properties of the microparticles as differential scanning calorimetry, Hot Stage microscopy, X-ray powder diffraction, and Fourier transform infrared spectroscopy analysis demonstrated. The drug and the lipid carrier presented in their original crystalline forms in both WPN and APN systems. A second objective of this study was to develop a novel mathematical model for describing the dynamic process of drug release from the solid lipid microparticles. For WPN microparticles the model predicted the changes of the drug release behavior with particle size and drug loading, while for APN microparticles the model fitting was not as good as for the WPN systems, confirming the influence of the atomizer on the drug release behavior.

  8. On the impact of airborne gravity data to fused gravity field models

    NASA Astrophysics Data System (ADS)

    Bolkas, Dimitrios; Fotopoulos, Georgia; Braun, Alexander

    2016-06-01

    In gravity field modeling, fused models that utilize satellite, airborne and terrestrial gravity observations are often employed to deal with erroneous terrestrially derived gravity datasets. These terrestrial datasets may suffer from long-wavelength systematic errors and inhomogeneous data coverage, which are not prevalent in airborne and satellite datasets. Airborne gravity acquisition plays an essential role in gravity field modeling, providing valuable information of the Earth's gravity field at medium and short wavelengths. Thus, assessing the impact of airborne gravity data to fused gravity field models is important for identifying problematic regions. Six study regions that represent different gravity field variability and terrestrial data point-density characteristics are investigated to quantify the impact of airborne gravity data to fused gravity field models. The numerical assessments of these representative regions resulted in predictions of airborne gravity impact for individual states and provinces in the USA and Canada, respectively. Prediction results indicate that, depending on the terrestrial data point-density and gravity field variability, the expected impact of airborne gravity can reach up to 3mGal (in terms of standard deviation) in Canada and Alaska (over areas of 1° × 1°). However, in the mainland US region, small changes are expected (0.2-0.4 mGal over areas of 1° × 1°) due to the availability of high spatial resolution terrestrial data. These results can serve as a guideline for setting airborne gravity data acquisition priorities and for improving future planning of airborne gravity surveys.

  9. Acoustic radiation- and streaming-induced microparticle velocities determined by microparticle image velocimetry in an ultrasound symmetry plane.

    PubMed

    Barnkob, Rune; Augustsson, Per; Laurell, Thomas; Bruus, Henrik

    2012-11-01

    We present microparticle image velocimetry measurements of suspended microparticles of diameters from 0.6 to 10 μm undergoing acoustophoresis in an ultrasound symmetry plane in a microchannel. The motion of the smallest particles is dominated by the Stokes drag from the induced acoustic streaming flow, while the motion of the largest particles is dominated by the acoustic radiation force. For all particle sizes we predict theoretically how much of the particle velocity is due to radiation and streaming, respectively. These predictions include corrections for particle-wall interactions and ultrasonic thermoviscous effects and match our measurements within the experimental uncertainty. Finally, we predict theoretically and confirm experimentally that the ratio between the acoustic radiation- and streaming-induced particle velocities is proportional to the actuation frequency, the acoustic contrast factor, and the square of the particle size, while it is inversely proportional to the kinematic viscosity.

  10. [Biodegradable polymer microparticles with entraped herbal extracts: preparation with supercritical carbon dioxide and use for tissue repair].

    PubMed

    Markvicheva, E A; Antonov, E N; Popova, A V; Bogorodskiĭ, S E; Likhareva, V V; Fel'dman, B M; Strukova, S M; Popov, V K; Rumsh, L D

    2009-01-01

    Biodegradable microparticles based on poly-D,L-lactide with entrapped mixture of herbal water-soluble extracts of Plantago major and Calendula officinalis were prepared. For preparation of these microparticles the previously developed method based on the usage of supercritical carbon dioxide (SC-CO2) was proposed. Microparticles were obtained by two techniques: 1) by preparing porous polymer monolith containing entrapped mixture of herbal extracts, which was then reduced to fine microparticles (ca. 0.1 mm) by dry ice grinding (called here as "monolithisation technique") and 2) by spraying of this polymer/extracts mixture through a jet (spray technique). In vitro release kinetic profile of herbal extract mixture was found to depend on the microparticle preparation technique, on the microparticle structure as well as on the initial ratio polymer/extracts (w/w). The microparticles were used for gastric ulcer treatment in a rat model. The extracts released from microparticles were found to accelerate tissue repair. PMID:20000125

  11. [Biodegradable polymer microparticles with entraped herbal extracts: preparation with supercritical carbon dioxide and use for tissue repair].

    PubMed

    Markvicheva, E A; Antonov, E N; Popova, A V; Bogorodskiĭ, S E; Likhareva, V V; Fel'dman, B M; Strukova, S M; Popov, V K; Rumsh, L D

    2009-01-01

    Biodegradable microparticles based on poly-D,L-lactide with entrapped mixture of herbal water-soluble extracts of Plantago major and Calendula officinalis were prepared. For preparation of these microparticles the previously developed method based on the usage of supercritical carbon dioxide (SC-CO2) was proposed. Microparticles were obtained by two techniques: 1) by preparing porous polymer monolith containing entrapped mixture of herbal extracts, which was then reduced to fine microparticles (ca. 0.1 mm) by dry ice grinding (called here as "monolithisation technique") and 2) by spraying of this polymer/extracts mixture through a jet (spray technique). In vitro release kinetic profile of herbal extract mixture was found to depend on the microparticle preparation technique, on the microparticle structure as well as on the initial ratio polymer/extracts (w/w). The microparticles were used for gastric ulcer treatment in a rat model. The extracts released from microparticles were found to accelerate tissue repair.

  12. Erythrocyte-derived microparticles supporting activated protein C-mediated regulation of blood coagulation.

    PubMed

    Koshiar, Ruzica Livaja; Somajo, Sofia; Norström, Eva; Dahlbäck, Björn

    2014-01-01

    Elevated levels of erythrocyte-derived microparticles are present in the circulation in medical conditions affecting the red blood cells. Erythrocyte-derived microparticles expose phosphatidylserine thus providing a suitable surface for procoagulant reactions leading to thrombin formation via the tenase and prothrombinase complexes. Patients with elevated levels of circulating erythrocyte-derived microparticles have increased thrombin generation in vivo. The aim of the present study was to investigate whether erythrocyte-derived microparticles are able to support the anticoagulant reactions of the protein C system. Erythrocyte-derived microparticles were isolated using ultracentrifugation after incubation of freshly prepared erythrocytes with the ionophore A23187 or from outdated erythrocyte concentrates, the different microparticles preparations yielding similar results. According to flow cytometry analysis, the microparticles exposed phoshatidylserine and bound lactadherin, annexin V, and protein S, which is a cofactor to activated protein C. The microparticles were able to assemble the tenase and prothrombinase complexes and to stimulate the formation of thrombin in plasma-based thrombin generation assay both in presence and absence of added tissue factor. The addition of activated protein C in the thrombin generation assay inhibited thrombin generation in a dose-dependent fashion. The anticoagulant effect of activated protein C in the thrombin generation assay was inhibited by a monoclonal antibody that prevents binding of protein S to microparticles and also attenuated by anti-TFPI antibodies. In the presence of erythrocyte-derived microparticles, activated protein C inhibited tenase and prothrombinase by degrading the cofactors FVIIIa and FVa, respectively. Protein S stimulated the Arg306-cleavage in FVa, whereas efficient inhibition of FVIIIa depended on the synergistic cofactor activity of protein S and FV. In summary, the erythrocyte-derived microparticle

  13. Tumor-Derived Tissue Factor-Bearing Microparticles are Associated with Venous Thromboembolic Events in Malignancy

    PubMed Central

    Zwicker, Jeffrey I.; Liebman, Howard A.; Neuberg, Donna; Lacroix, Romaric; Bauer, Kenneth A.; Furie, Barbara C.; Furie, Bruce

    2009-01-01

    Purpose Despite the strong association between malignant disease and thromboembolic disorders, the molecular and cellular basis of this relationship remains uncertain. We evaluated the hypothesis that tumor-derived tissue factor-bearing microparticles in plasma contribute to cancer-associated thrombosis. Experimental Design We developed impedance-based flow cytometry to detect, quantitate and size microparticles in platelet-poor plasma. We evaluated the number of tissue factor-bearing microparticles in a cohort of cancer patients of different histologies (N=96) and performed a case control study of 30 cancer patients diagnosed with an acute venous thromboembolic event (VTE) compared to 60 cancer patients of similar age, stage, sex, diagnosis without known VTE as well as 22 patients with an idiopathic VTE. Results Tissue factor-bearing microparticles were detected in patients with advanced malignancy including two thirds of patients with pancreatic carcinoma. Elevated levels of tissue factor-bearing microparticles were associated VTE in cancer patients (adjusted OR 3.72, 95% CI 1.18-11.76, P=0.01). In cancer patients without VTE, a retrospective analysis revealed a one-year cumulative incidence of VTE of 34.8% in patients with tissue factor-bearing microparticles versus 0% those without detectable tissue factor-bearing microparticles (Gray test p-value=0.002). The median number of tissue factor-bearing microparticles in the cancer VTE cohort (7.1 × 104 microparticles/μl) was significantly greater than both the idiopathic VTE and cancer-no VTE groups (P=0.002 and P=0.03, respectively). Pancreatectomy in three patients eliminated or nearly eliminated these microparticles which co-expressed the epithelial tumor antigen, MUC-1. Conclusion We conclude that tumor-derived tissue factor-bearing microparticles are associated with VTE in cancer patients and may be central to the pathogenesis of cancer-associated thrombosis. PMID:19861441

  14. Airborne Particulate Threat Assessment

    SciTech Connect

    Patrick Treado; Oksana Klueva; Jeffrey Beckstead

    2008-12-31

    Aerosol threat detection requires the ability to discern between threat agents and ambient background particulate matter (PM) encountered in the environment. To date, Raman imaging technology has been demonstrated as an effective strategy for the assessment of threat agents in the presence of specific, complex backgrounds. Expanding our understanding of the composition of ambient particulate matter background will improve the overall performance of Raman Chemical Imaging (RCI) detection strategies for the autonomous detection of airborne chemical and biological hazards. Improving RCI detection performance is strategic due to its potential to become a widely exploited detection approach by several U.S. government agencies. To improve the understanding of the ambient PM background with subsequent improvement in Raman threat detection capability, ChemImage undertook the Airborne Particulate Threat Assessment (APTA) Project in 2005-2008 through a collaborative effort with the National Energy Technology Laboratory (NETL), under cooperative agreement number DE-FC26-05NT42594. During Phase 1 of the program, a novel PM classification based on molecular composition was developed based on a comprehensive review of the scientific literature. In addition, testing protocols were developed for ambient PM characterization. A signature database was developed based on a variety of microanalytical techniques, including scanning electron microscopy, FT-IR microspectroscopy, optical microscopy, fluorescence and Raman chemical imaging techniques. An automated particle integrated collector and detector (APICD) prototype was developed for automated collection, deposition and detection of biothreat agents in background PM. During Phase 2 of the program, ChemImage continued to refine the understanding of ambient background composition. Additionally, ChemImage enhanced the APICD to provide improved autonomy, sensitivity and specificity. Deliverables included a Final Report detailing our

  15. A Microfluidic Device for Continuous-Flow Magnetically Controlled Capture and Isolation of Microparticles.

    PubMed

    Zhou, Yao; Wang, Yi; Lin, Qiao

    2010-08-01

    This paper presents a novel microfluidic device that exploits magnetic manipulation for integrated capture and isolation of microparticles in continuous flow. The device, which was fabricated from poly(dimethylsiloxane) (PDMS) by soft-lithography techniques, consists of an incubator and a separator integrated on a single chip. The incubator is based on a novel scheme termed target acquisition by repetitive traversal (TART), in which surface-functionalized magnetic beads repetitively traverse a sample to seek out and capture target particles. This is accomplished by a judicious combination of a serpentine microchannel geometry and a time-invariant magnetic field. Subsequently, in the separator, the captured target particles are isolated from nontarget particles via magnetically driven fractionation in the same magnetic field. Due to the TART incubation scheme that uses a corner-free serpentine channel, the device has no dead volume and allows minimization of undesired particle or magnetic-bead retention. Single-chip integration of the TART incubator with the magnetic-fractionation separator further allows automated continuous isolation and retrieval of specific microparticles in an integrated manner that is free of manual off-chip sample incubation, as often required by alternative approaches. Experiments are conducted to characterize the individual incubation and separation components, as well as the integrated device. The device is found to allow 90% of target particles in a sample to be captured and isolated and 99% of nontarget particles to be eliminated. With this high separation efficiency, along with excellent reliability and flexibility, the device is well suited to sorting, purification, enrichment, and detection of micro/nanoparticles and cells in lab-on-a-chip systems.

  16. Effect of short-chain fatty acids on the formation of amylose microparticles by amylosucrase.

    PubMed

    Lim, Min-Cheol; Park, Kyu-Hwan; Choi, Jong-Hyun; Lee, Da-Hee; Letona, Carlos Andres Morales; Baik, Moo-Yeol; Park, Cheon-Seok; Kim, Young-Rok

    2016-10-20

    Amylose microparticles can be produced by self-assembly of amylose molecules through an amylosucrase-mediated synthesis. Here we investigated the role of short-chain fatty acids in the formation of amylose microparticles and the fate of these fatty acids at the end of the reaction. The rate of self-assembly and production yields of amylose microparticles were significantly enhanced in the presence of fatty acids. The effect was dependent on the length of the fatty acid carbon tail; butanoic acid (C4) was the most effective, followed by hexanoic acid (C6) and octanoic acid (C8). The amylose microparticles were investigated by carrying out SEM, XRD, Raman, NMR, FT-IR and DSC analysis. The size, morphology and crystal structure of the resulting amylose microparticles were comparable with those of amylose microparticles produced without fatty acids. The results indicated the carboxyl group of the fatty acid to be responsible for promoting the self-assembly of amylose chains to form microparticles. The fatty acids were eventually removed from the microstructure through the tight association of amylose double helices to form the amylose microparticles. PMID:27474606

  17. Preparation, Characterization and Release Properties of Nanostructured Polystyrene Microparticles Containing Different Silicates

    SciTech Connect

    Scarfato, Paola; Iannelli, Pio; Russo, Pietro; Acierno, Domenico

    2010-06-02

    Nanostructured polystyrene microparticles containing different silicates as nanosized filler were successfully prepared using an emulsification/solvent evaporation method. X-ray diffraction showed that all hybrid systems were in an intercalated morphology. The microparticles display regular geometry, improved thermal resistance and release behavior dependent upon the silicate type in the hybrid, as demonstrated by preliminary investigations performed using benzophenone as model penetrant.

  18. Formulation and characterization of mucoadhesive microparticles of cinnarizine hydrochloride using supercritical fluid technique.

    PubMed

    Patel, Jayvadan K; Patil, Priyanka S; Sutariya, Vijaykumar B

    2013-06-01

    The mucoadhesive microparticles (CHCNZ) composed of chitosan (CH) and cinnarizine (CNZ) hydrochloride were successfully prepared, in a process of solution-enhanced dispersion, by supercritical CO₂ (SEDS) technique. Scanning electron microscopy was used to reveal the morphological characteristics of mucoadhesive microparticles. The average particle size of microparticles was in the range from 1.9 to 12.8 µm. In vitro and in vivo mucoadhesive tests showed that CHCNZ mucoadhesive microparticles adhered more strongly to gastric mucous layer. Thereby retaining in gastrointestinal tract for an extended period of time and exhibiting good mucoadhesive properties. The X-ray powder diffractometry and differential scanning calorimetry analysis demonstrated that the SEDS process was an efficient physical coating process to produce CHCNZ composite microparticles. It also suggests that CNZ did not undergo chemical changes during the production of microparticles. The optimized batch exhibited a high drug entrapment efficiency of 67% with particle size of 3.9 µm. A sustained pattern of drug release was obtained for more than 20 h. In vivo studies were carried out by administering orally cinnarizine HCl (CNZ) suspension and mucoadhesive microparticles to rabbits under fasted (for 12 h) conditions. The results showed that CNZ mucoadhesive microparticles had a better bioavailability than CNZ suspension due to longer retention in the gastric environment of the test animals. PMID:23286919

  19. Microparticles prepared from biodegradable polyhydroxyalkanoates as matrix for encapsulation of cytostatic drug.

    PubMed

    Murueva, A V; Shishatskaya, E I; Kuzmina, A M; Volova, T G; Sinskey, A J

    2013-08-01

    Microparticles made from degradable polyhydroxyalkanoates of different chemical compositions a homopolymer of 3-hydroxybutyric acid, copolymers of 3-hydroxybutyric and 4-hydroxybutyric acids (P3HB/4HB), 3-hydroxybutyric and 3-hydroxyvaleric acids (P3HB/3HV), 3-hydroxybutyric and 3-hydroxyhexanoic acids (P3HB/3HHx) were prepared using the solvent evaporation technique, from double emulsions. The study addresses the influence of the chemical compositions on the size and ξ-potential of microparticles. P3HB microparticles loaded with doxorubicin have been prepared and investigated. Their average diameter and ξ-potential have been found to be dependent upon the level of loading (1, 5, and 10 % of the polymer mass). Investigation of the in vitro drug release behavior showed that the total drug released from the microparticle into the medium increased with mass concentration of the drug. In this study mouse fibroblast NIH 3T3 cells were cultivated on PHA microparticles, and results of using fluorescent DAPI DNA stain, and MTT assay showed that microparticles prepared from PHAs of different chemical compositions did not exhibit cytotoxicity to cells cultured on them and proved to be highly biocompatible. Cell attachment and proliferation on PHA microparticles were similar to those on polystyrene. The cytostatic drug encapsulated in P3HB/3HV microparticles has been proven to be effective against HeLa tumor cells.

  20. Prospects of pharmaceuticals and biopharmaceuticals loaded microparticles prepared by double emulsion technique for controlled delivery

    PubMed Central

    Giri, Tapan Kumar; Choudhary, Chhatrapal; Ajazuddin; Alexander, Amit; Badwaik, Hemant; Tripathi, Dulal Krishna

    2012-01-01

    Several methods and techniques are potentially useful for the preparation of microparticles in the field of controlled drug delivery. The type and the size of the microparticles, the entrapment, release characteristics and stability of drug in microparticles in the formulations are dependent on the method used. One of the most common methods of preparing microparticles is the single emulsion technique. Poorly soluble, lipophilic drugs are successfully retained within the microparticles prepared by this method. However, the encapsulation of highly water soluble compounds including protein and peptides presents formidable challenges to the researchers. The successful encapsulation of such compounds requires high drug loading in the microparticles, prevention of protein and peptide degradation by the encapsulation method involved and predictable release, both rate and extent, of the drug compound from the microparticles. The above mentioned problems can be overcome by using the double emulsion technique, alternatively called as multiple emulsion technique. Aiming to achieve this various techniques have been examined to prepare stable formulations utilizing w/o/w, s/o/w, w/o/o, and s/o/o type double emulsion methods. This article reviews the current state of the art in double emulsion based technologies for the preparation of microparticles including the investigation of various classes of substances that are pharmaceutically and biopharmaceutically active. PMID:23960828

  1. CALIBRATION OF THERMOLUMINESCENCE AND FILM DOSEMETERS FOR SKIN DOSES FROM HIGH-ACTIVITY MICROPARTICLES.

    PubMed

    Eakins, J S; Hager, L G; Tanner, R J

    2016-09-01

    The use of EXT-RAD™ extremity TLDs and radiochromic film to measure doses from primarily beta-emitting microparticles is discussed. Specific calibration techniques have been developed, using both Monte Carlo modelling and experiments. Results for a (90)Sr/(90)Y microparticle are presented to illustrate the general techniques and to demonstrate reasonable agreement between the dosimetry methods.

  2. Preliminary results of experimental measurements to determine microparticle charge in a complex plasma

    NASA Astrophysics Data System (ADS)

    Gillman, Eric; Amatucci, Bill

    2015-09-01

    Microparticles in a dusty plasma typically collect many of the more mobile electrons as they charge up and therefore typically attain a net negative potential. The charge on these microparticles is typically estimated by calculating the charge on a spherical capacitor at the floating potential or by making measurements of particles levitating in the plasma sheath. However, secondary processes can alter the charging process and are significantly altered in the plasma sheath. Currently there is no reliable method to measure microparticle surface charge in the bulk region of complex or dusty plasmas. A novel, non-invasive, experimental method of measuring the charging of microparticles in the bulk region of a plasma will be presented. Ions impinging directly upon the microparticle surface and interacting electrostatically with the charged microparticle, known as collisional and electrostatic Coulomb ion drag, respectively, slows particle acceleration due to gravity as the particle falls through a plasma discharge. Since ion and neutral drag are commonly the dominant forces on microparticles in complex plasmas, the reduced acceleration is measured without a plasma to determine the neutral drag. By repeating the measurement with a plasma and subtracting the neutral drag, the ion drag is obtained. The microparticle net charge is then ascertained from the ion drag on isolated grains falling through a plasma discharge. This work was supported by the Naval Research Laboratory Base Program.

  3. Characterization of microparticles prepared by emulsion method from pectin and protein

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In this study, pectin was extracted from apple peel and formulated into microparticles in combination with zein, an edible food protein. The physical, chemical, and structural properties of the resultant pectin structures were evaluated. The resultant microparticles were also examined in vitro for c...

  4. Prospects of pharmaceuticals and biopharmaceuticals loaded microparticles prepared by double emulsion technique for controlled delivery.

    PubMed

    Giri, Tapan Kumar; Choudhary, Chhatrapal; Ajazuddin; Alexander, Amit; Badwaik, Hemant; Tripathi, Dulal Krishna

    2013-04-01

    Several methods and techniques are potentially useful for the preparation of microparticles in the field of controlled drug delivery. The type and the size of the microparticles, the entrapment, release characteristics and stability of drug in microparticles in the formulations are dependent on the method used. One of the most common methods of preparing microparticles is the single emulsion technique. Poorly soluble, lipophilic drugs are successfully retained within the microparticles prepared by this method. However, the encapsulation of highly water soluble compounds including protein and peptides presents formidable challenges to the researchers. The successful encapsulation of such compounds requires high drug loading in the microparticles, prevention of protein and peptide degradation by the encapsulation method involved and predictable release, both rate and extent, of the drug compound from the microparticles. The above mentioned problems can be overcome by using the double emulsion technique, alternatively called as multiple emulsion technique. Aiming to achieve this various techniques have been examined to prepare stable formulations utilizing w/o/w, s/o/w, w/o/o, and s/o/o type double emulsion methods. This article reviews the current state of the art in double emulsion based technologies for the preparation of microparticles including the investigation of various classes of substances that are pharmaceutically and biopharmaceutically active. PMID:23960828

  5. Airborne GLM Simulator (FEGS)

    NASA Astrophysics Data System (ADS)

    Quick, M.; Blakeslee, R. J.; Christian, H. J., Jr.; Stewart, M. F.; Podgorny, S.; Corredor, D.

    2015-12-01

    Real time lightning observations have proven to be useful for advanced warning and now-casting of severe weather events. In anticipation of the launch of the Geostationary Lightning Mapper (GLM) onboard GOES-R that will provide continuous real time observations of total (both cloud and ground) lightning, the Fly's Eye GLM Simulator (FEGS) is in production. FEGS is an airborne instrument designed to provide cal/val measurements for GLM from high altitude aircraft. It consists of a 5 x 5 array of telescopes each with a narrow passband filter to isolate the 777.4 nm neutral oxygen emission triplet radiated by lightning. The telescopes will measure the optical radiance emitted by lightning that is transmitted through the cloud top with a temporal resolution of 10 μs. When integrated on the NASA ER-2 aircraft, the FEGS array with its 90° field-of-view will observe a cloud top area nearly equal to a single GLM pixel. This design will allow FEGS to determine the temporal and spatial variation of light that contributes to a GLM event detection. In addition to the primary telescope array, the instrument includes 5 supplementary optical channels that observe alternate spectral emission features and will enable the use of FEGS for interesting lightning physics applications. Here we present an up-to-date summary of the project and a description of its scientific applications.

  6. Suppression of atopic dermatitis in mice model by reducing inflammation utilizing phosphatidylserine-coated biodegradable microparticles.

    PubMed

    Kumar, Purnima; Hosain, Md Zahangir; Kang, Jeong-Hun; Takeo, Masafumi; Kishimura, Akihiro; Mori, Takeshi; Katayama, Yoshiki

    2015-01-01

    Controlling inflammatory response is important to avoid chronic inflammation in many diseases including atopic dermatitis (AD). In this research, we tried using a phosphatidylserine (PS)-coated microparticles in the AD mouse model for achieving the modulation of the macrophage phenotype to an anti-inflammatory state. Here, we prepared poly (D,L-lactic acid) microparticle coated with PS on the outside shell. We confirmed the cellular uptake of the PS-coated microparticle, which leads to the significant downregulation of the inflammatory cytokine production. In the mouse model of AD, the PS-coated microparticle was injected subcutaneously for a period of 12 days. The mice showed significant reduction in the development of AD symptoms comparing with the mice treated with the PC-coated microparticle. PMID:26414796

  7. The role of microparticles in inflammation and transfusion: A concise review.

    PubMed

    Cognasse, Fabrice; Hamzeh-Cognasse, Hind; Laradi, Sandrine; Chou, Ming-Li; Seghatchian, Jerard; Burnouf, Thierry; Boulanger, Chantal; Garraud, Olivier; Amabile, Nicolas

    2015-10-01

    Microparticles are small membrane-bound vesicles found in body fluids including peripheral blood. Microparticles are an intrinsic part of blood labile products delivered to transfused patients and have active roles in inflammation. They are delimited by a lipid bilayer composed mainly of phospholipids, cholesterol, membrane-associated proteins, intracellular components such as metabolic enzymes, proteins-involved in adhesion and fusion, cytoskeletal-associated proteins, surface glycoproteins and/or chemokines. Microparticles can trigger a pro-inflammatory message to neighbouring or target cells. Microparticles originating from platelets, leukocytes, erythrocytes, and endothelial cells are associated with a variety of pathophysiological conditions. This review summarises the role of Microparticles in modulating inflammation. PMID:26584596

  8. Microparticle injection effects on microwave transmission through an overly dense plasma layer

    SciTech Connect

    Gillman, Eric D. Amatucci, W. E.; Williams, Jeremiah; Compton, C. S.

    2015-04-15

    Microparticles injected into a plasma have been shown to deplete the free electron population as electrons are collected through the process of microparticles charging to the plasma floating potential. However, these charged microparticles can also act to scatter electromagnetic signals. These experiments investigate microwave penetration through a previously impenetrable overly dense plasma layer as microparticles are injected and the physical phenomena associated with the competing processes that occur due to electron depletion and microwave scattering. The timescales for when each of these competing processes dominates is analyzed in detail. It was found that while both processes play a significant and dominant role at different times, ultimately, transmission through this impenetrable plasma layer can be significantly increased with microparticle injection.

  9. Preparation and in vitro release of zein microparticles loaded with prednisolone for oral delivery.

    PubMed

    Lau, Esther T L; Johnson, Stuart K; Mikkelsen, Deirdre; Halley, Peter J; Steadman, Kathryn J

    2012-01-01

    Zein has been proposed as a polymer for targeted-drug delivery via the oral route. Zein microparticles were loaded with prednisolone and evaluated as an oral delivery system. Microparticles were formulated using phase separation. Starting quantities of zein and prednisolone, along with the agitation method and temperature were found to significantly impact drug loading and loading efficiency. Vortex mixing produced the highest drug loading and loading efficiency. Drug release was measured in simulated conditions of the stomach and small intestine using the microparticles made with the method that best improved drug loading. In simulated stomach and small intestine conditions, prednisolone release reached almost 70% over 3 and 4 h, respectively. While a clinically relevant dose may be delivered using c. 100 mg of zein microparticles, prednisolone release from the microparticles indicates that they may not be suited as a controlled- or targeted-delivery system. PMID:22612552

  10. Assessing consumption of bioactive micro-particles by filter-feeding Asian carp

    USGS Publications Warehouse

    Jensen, Nathan R.; Amberg, Jon J.; Luoma, James A.; Walleser, Liza R.; Gaikowski, Mark P.

    2012-01-01

    Silver carp Hypophthalmichthys molitrix (SVC) and bighead carp H. nobilis (BHC) have impacted waters in the US since their escape. Current chemical controls for aquatic nuisance species are non-selective. Development of a bioactive micro-particle that exploits filter-feeding habits of SVC or BHC could result in a new control tool. It is not fully understood if SVC or BHC will consume bioactive micro-particles. Two discrete trials were performed to: 1) evaluate if SVC and BHC consume the candidate micro-particle formulation; 2) determine what size they consume; 3) establish methods to evaluate consumption of filter-feeders for future experiments. Both SVC and BHC were exposed to small (50-100 μm) and large (150-200 μm) micro-particles in two 24-h trials. Particles in water were counted electronically and manually (microscopy). Particles on gill rakers were counted manually and intestinal tracts inspected for the presence of micro-particles. In Trial 1, both manual and electronic count data confirmed reductions of both size particles; SVC appeared to remove more small particles than large; more BHC consumed particles; SVC had fewer overall particles in their gill rakers than BHC. In Trial 2, electronic counts confirmed reductions of both size particles; both SVC and BHC consumed particles, yet more SVC consumed micro-particles compared to BHC. Of the fish that ate micro-particles, SVC consumed more than BHC. It is recommended to use multiple metrics to assess consumption of candidate micro-particles by filter-feeders when attempting to distinguish differential particle consumption. This study has implications for developing micro-particles for species-specific delivery of bioactive controls to help fisheries, provides some methods for further experiments with bioactive micro-particles, and may also have applications in aquaculture.

  11. Triboelectric and plasma charging of microparticles

    NASA Astrophysics Data System (ADS)

    Heijmans, L. C. J.; Nijdam, S.

    2016-06-01

    The charge on two sets of 100 μm polystyrene particles has been measured using their acceleration in an externally applied electric field. This allows for the measurement of the individual charge on multiple particles at the same time. It is found that particles will charge each other both positively and negatively due to the triboelectric effect. This leads to a broad particle-charge distribution with positive, negative and neutral particles. The particle charge can be largely removed by applying a plasma over the particle containing surface. After plasma charge removal, the particles are triboelectrically recharged when they come into contact with other materials.

  12. Airborne Laser Polar Nephelometer

    NASA Technical Reports Server (NTRS)

    Grams, Gerald W.

    1973-01-01

    A polar nephelometer has been developed at NCAR to measure the angular variation of the intensity of light scattered by air molecules and particles. The system has been designed for airborne measurements using outside air ducted through a 5-cm diameter airflow tube; the sample volume is that which is common to the intersection of a collimated source beam and the detector field of view within the airflow tube. The source is a linearly polarized helium-neon laser beam. The optical system defines a collimated field-of-view (0.5deg half-angle) through a series of diaphragms located behind a I72-mm focal length objective lens. A photomultiplier tube is located immediately behind an aperture in the focal plane of the objective lens. The laser beam is mechanically chopped (on-off) at a rate of 5 Hz; a two-channel pulse counter, synchronized to the laser output, measures the photomultiplier pulse rate with the light beam both on and off. The difference in these measured pulse rates is directly proportional to the intensity of the scattered light from the volume common to the intersection of the laser beam and the detector field-of-view. Measurements can be made at scattering angles from 15deg to 165deg with reference to the direction of propagation of the light beam. Intermediate angles are obtained by selecting the angular increments desired between these extreme angles (any multiple of 0.1deg can be selected for the angular increment; 5deg is used in normal operation). Pulses provided by digital circuits control a stepping motor which sequentially rotates the detector by pre-selected angular increments. The synchronous photon-counting system automatically begins measurement of the scattered-light intensity immediately after the rotation to a new angle has been completed. The instrument has been flown on the NASA Convair 990 airborne laboratory to obtain data on the complex index of refraction of atmospheric aerosols. A particle impaction device is operated simultaneously

  13. Scaffold pore space modulation through intelligent design of dissolvable microparticles.

    PubMed

    Liebschner, Michael A K; Wettergreen, Matthew

    2012-01-01

    The goal of this area of research is to manipulate the pore space of scaffolds through the application of an intelligent design concept on dissolvable microparticles. To accomplish this goal, we developed an efficient and repeatable process for fabrication of microparticles from multiple materials using a combination of rapid prototyping (RP) and soft lithography. Phase changed 3D printing was used to create masters for PDMS molds. A photocrosslinkable polymer was then delivered into these molds to make geometrically complex 3D microparticles. This repeatable process has demonstrated to generate the objects with greater than 95% repeatability with complete pattern transfer. This process was illustrated for three different shapes of various complexities. The shapes were based on the extrusion of 2D shapes. This may allow simplification of the fabrication process in the future combined with a direct transfer of the findings. Altering the shapes of particles used for porous scaffold fabrication will allow for tailoring of the pore shapes, and therefore their biological function within a porous tissue engineering scaffold. Through permeation experiments, we have shown that the pore geometry may alter the permeability coefficient of scaffolds while influencing mechanical properties to a lesser extent. By selecting different porogen shapes, the nutrition transport and scaffold degradation can be significantly influenced with minimal effect on the mechanical integrity of the construct. In addition, the different shapes may allow a control of drug release by modifying their surface-to-volume ratio, which could modulate drug delivery over time. While soft lithography is currently used with photolithography, its high precision is offset by high cost of production. The employment of RP to a specific resolution offers a much less expensive alternative with increased throughput due to the speed of current RP systems.

  14. Laser Plasma Jet Driven Microparticles for DNA/Drug Delivery

    PubMed Central

    Menezes, Viren; Mathew, Yohan; Takayama, Kazuyoshi; Kanno, Akira; Hosseini, Hamid

    2012-01-01

    This paper describes a microparticle delivery device that generates a plasma jet through laser ablation of a thin metal foil and uses the jet to accomplish particle delivery into soft living targets for transferring biological agents. Pure gold microparticles of 1 µm size were coated with a plasmid DNA, pIG121Hm, and were deposited as a thin layer on one surface of an aluminum foil. The laser (Nd:YAG, 1064 nm wavelength) ablation of the foil generated a plasma jet that carried the DNA coated particles into the living onion cells. The particles could effectively penetrate the target cells and disseminate the DNA, effecting the transfection of the cells. Generation of the plasma jet on laser ablation of the foil and its role as a carrier of microparticles was visualized using a high-speed video camera, Shimadzu HPV-1, at a frame rate of 500 kfps (2 µs interframe interval) in a shadowgraph optical set-up. The particle speed could be measured from the visualized images, which was about 770 m/s initially, increased to a magnitude of 1320 m/s, and after a quasi-steady state over a distance of 10 mm with an average magnitude of 1100 m/s, started declining, which typically is the trend of a high-speed, pulsed, compressible jet. Aluminum launch pad (for the particles) was used in the present study to make the procedure cost-effective, whereas the guided, biocompatible launch pads made of gold, silver or titanium can be used in the device during the actual clinical operations. The particle delivery device has a potential to have a miniature form and can be an effective, hand-held drug/DNA delivery device for biological applications. PMID:23226394

  15. Laser plasma jet driven microparticles for DNA/drug delivery.

    PubMed

    Menezes, Viren; Mathew, Yohan; Takayama, Kazuyoshi; Kanno, Akira; Hosseini, Hamid

    2012-01-01

    This paper describes a microparticle delivery device that generates a plasma jet through laser ablation of a thin metal foil and uses the jet to accomplish particle delivery into soft living targets for transferring biological agents. Pure gold microparticles of 1 µm size were coated with a plasmid DNA, pIG121Hm, and were deposited as a thin layer on one surface of an aluminum foil. The laser (Nd:YAG, 1064 nm wavelength) ablation of the foil generated a plasma jet that carried the DNA coated particles into the living onion cells. The particles could effectively penetrate the target cells and disseminate the DNA, effecting the transfection of the cells. Generation of the plasma jet on laser ablation of the foil and its role as a carrier of microparticles was visualized using a high-speed video camera, Shimadzu HPV-1, at a frame rate of 500 kfps (2 µs interframe interval) in a shadowgraph optical set-up. The particle speed could be measured from the visualized images, which was about 770 m/s initially, increased to a magnitude of 1320 m/s, and after a quasi-steady state over a distance of 10 mm with an average magnitude of 1100 m/s, started declining, which typically is the trend of a high-speed, pulsed, compressible jet. Aluminum launch pad (for the particles) was used in the present study to make the procedure cost-effective, whereas the guided, biocompatible launch pads made of gold, silver or titanium can be used in the device during the actual clinical operations. The particle delivery device has a potential to have a miniature form and can be an effective, hand-held drug/DNA delivery device for biological applications. PMID:23226394

  16. Trapping of Microparticles in Cylindrical Standing Wave Fields

    NASA Astrophysics Data System (ADS)

    Yang, Jeongwon; Hwang, Haerang; Bae, Young Min; Kim, Moojoon; Ha, Kanglyeol

    2013-07-01

    In this study, in order to determine the positions where microparticles are trapped in a cylindrical standing wave field, we derived equations giving the radiation force and potential energy distribution. Then, the trapped pattern and its variation with time in a hollow cylindrical transducer were simulated. The simulation results showed that polystyrene particles moved to and aggregated near positions corresponding to pressure nodes, which were estimated from the derived equations. These were confirmed by measurement. In addition, it was demonstrated that biological particles of the green algae chlorella show similar trapping phenomena to polystyrene particles.

  17. Microparticles deep in the plasma sheath: Coulomb 'explosion'

    SciTech Connect

    Antonova, T.; Du, C.-R.; Ivlev, A. V.; Hou, L.-J.; Thomas, H. M.; Morfill, G. E.; Annaratone, B. M.

    2012-09-15

    A cloud of microparticles was trapped deep in the sheath of a radio-frequency (rf) discharge, very close to the lower (grounded) electrode of the plasma chamber. This was achieved by employing a specifically designed rf-driven segment integrated in the lower electrode, which provided an additional confinement compressing the cloud to a very high density. After switching the rf-driven segment off, the cloud 'exploded' due to mutual interparticle repulsion. By combining a simple theoretical model with different numerical simulation methods, some basic properties of complex plasmas in this highly non-equilibrium regime were determined.

  18. Microparticles in sickle cell anaemia: promise and pitfalls.

    PubMed

    Hebbel, Robert P; Key, Nigel S

    2016-07-01

    Blood from patients with sickle cell disease contains microparticles (MP) derived from multiple cell sources, including red cells, platelets, monocytes and endothelial cells. MPs are of great interest because of their disease associations, their status as promising biomarkers, and the intercellular communications they mediate. To illustrate the likelihood of their relevance in sickle cell disease, we discuss the nature of MP, their profiling in sickle disease, some caveats relevant to their detection, their roles in supporting coagulation and the disparate influences they may exert upon the pathobiology of sickle cell disease.

  19. Preparation of naproxen-ethyl cellulose microparticles by spray-drying technique and their application to textile materials.

    PubMed

    Arici, Mesut; Topbas, Ozlem; Karavana, Sinem Yaprak; Ertan, Gokhan; Sariisik, Merih; Ozturk, Cihat

    2014-01-01

    The objective of this study is to develop a new textile-based drug delivery system containing naproxen (NAP) microparticles and to evaluate the potential of the system as the carrier of NAP for topical delivery. Microparticles were prepared by spray-drying using an aqueous ethyl cellulose dispersion. The drug content and entrapment efficiency, particle size and distribution, particle morphology and in vitro drug release characteristics of microparticles were optimized for the application of microparticles onto the textile fabrics. Microparticles had spherical shape in the range of 10-15 μm and a narrow particle size distribution. NAP encapsulated in microparticles was in the amorphous or partially crystalline nature. Microparticles were tightly fixed onto the textile fabrics. In vitro drug release exhibited biphasic release profile with an initial burst followed by a very slow release. Skin permeation profiles were observed to follow near zero-order release kinetics. PMID:24861324

  20. Airborne laser topographic mapping results

    NASA Technical Reports Server (NTRS)

    Krabill, W. B.; Collins, J. G.; Link, L. E.; Swift, R. N.; Butler, M. L.

    1984-01-01

    The results of terrain mapping experiments utilizing the National Aeronautics and Space Administration (NASA) Airborne Oceanographic Lidar (AOL) over forested areas are presented. The flight tests were conducted as part of a joint NASA/U.S. Army Corps of Engineers (CE) investigation aimed at evaluating the potential of an airborne laser ranging system to provide cross-sectional topographic data on flood plains that are difficult and expensive to survey using conventional techniques. The data described in this paper were obtained in the Wolf River Basin located near Memphis, TN. Results from surveys conducted under winter 'leaves off' and summer 'leaves on' conditions, aspects of day and night operation, and data obtained from decidous and coniferous tree types are compared. Data processing techniques are reviewed. Conclusions relative to accuracy and present limitations of the AOL, and airborne lidar systems in general, to terrain mapping over forested areas are discussed.

  1. An airborne isothermal haze chamber

    NASA Technical Reports Server (NTRS)

    Hindman, E. E.

    1981-01-01

    Thermal gradient diffusion cloud chambers (TGDCC) are used to determine the concentrations of cloud condensation nuclei (CCN) with critical supersaturations greater than or equal to about 0.2%. The CCN concentrations measured with the airborne IHC were lower than theoretically predicted by factors ranging between 7.9 and 9.0. The CCN concentrations measured with the airborne IHC were lower than the concentrations measured with the larger laboratory IHC's by factors ranging between 3.9 and 7.5. The bounds of the supersaturation ranges of the airborne IHC and the CSU-Mee TGDCC do not overlap. Nevertheless, the slopes of the interpolated data between the bounds agree favorably with the theoretical slopes.

  2. WESTERN AIRBORNE CONTAMINANTS ASSESSMENT PROJECT RESEARCH PLAN

    EPA Science Inventory

    The goal of the Western Airborne Contaminants Assessment Project (WACAP) is to assess the deposition of airborne contaminants in Western National Parks, providing regional and local information on exposure, accumulation, impacts, and probable sources. This project is being desig...

  3. Microparticle content of platelet concentrates is predicted by donor microparticles and is altered by production methods and stress.

    PubMed

    Maurer-Spurej, Elisabeth; Larsen, Rune; Labrie, Audrey; Heaton, Andrew; Chipperfield, Kate

    2016-08-01

    In circulation, shedding of microparticles from a variety of viable cells can be triggered by pathological activation of inflammatory processes, by activation of coagulation or complement systems, or by physical stress. Elevated microparticle content (MPC) in donor blood might therefore indicate a clinical condition of the donor which, upon transfusion, might affect the recipient. In blood products, elevated MPC might also represent product stress. Surprisingly, the MPC in blood collected from normal blood donors is highly variable, which raises the question whether donor microparticles are present in-vivo and transfer into the final blood component, and how production methods and post-production processing might affect the MPC. We measured MPC using ThromboLUX in (a) platelet-rich plasma (PRP) of 54 apheresis donors and the corresponding apheresis products, (b) 651 apheresis and 646 pooled platelet concentrates (PCs) with plasma and 414 apheresis PCs in platelet additive solution (PAS), and (c) apheresis PCs before and after transportation, gamma irradiation, and pathogen inactivation (N = 8, 7, and 12 respectively). ThromboLUX-measured MPC in donor PRP and their corresponding apheresis PC samples were highly correlated (r = 0.82, P = .001). The average MPC in pooled PC was slightly lower than that in apheresis PC and substantially lower in apheresis PC stored with PAS rather than plasma. Mirasol Pathogen Reduction treatment significantly increased MPC with age. Thus, MPC measured in donor samples might be a useful predictor of product stability, especially if post-production processes are necessary. PMID:27470708

  4. Airborne Transmission of Bordetella pertussis

    PubMed Central

    Warfel, Jason M.; Beren, Joel; Merkel, Tod J.

    2012-01-01

    Pertussis is a contagious, acute respiratory illness caused by the bacterial pathogen Bordetella pertussis. Although it is widely believed that transmission of B. pertussis occurs via aerosolized respiratory droplets, no controlled study has ever documented airborne transmission of pertussis. We set out to determine if airborne transmission occurs between infected and naive animals, utilizing the baboon model of pertussis. Our results showed that 100% of exposed naive animals became infected even when physical contact was prevented, demonstrating that pertussis transmission occurs via aerosolized respiratory droplets. PMID:22807521

  5. Sampling of airborne polycyclic aromatic hydrocarbons

    SciTech Connect

    Otson, R.; Leach, J.M.; Chung, L.T.K.

    1987-07-01

    Limitations of NIOSH sampling method P and CAM 183 were defined for airborne standard mixtures of polycyclic aromatic hydrocarbons (PAH) generated as vapors in a flow-through apparatus. The PAH fell into three categories: those that were too volatile to be collected by the NIOSH filtration method at normal ambient temperatures and were best sampled with Tenax or XAD-2 sorbent (i.e., indane, naphthalene, biphenyl, acenaphthene, fluorene, 9,10-dihydrophenanthrene, phenathrene, and anthracene); those that were quantitatively collected by filters, even after a brief airborne residence time (i.e., benz(a)anthracene, chrysene, benzo(a)pyrene, dibenz(a,h)anthracene, and benzo(ghi)perylene); and those that partitioned between filter and sorbent (i.e., fluoranthene and pyrene). A combination glass fiber/silver membrane filter backed by two sorbent tubes in series gave overall mean recoveries of 94-96% for the 15 PAH studied at total concentrations of, nominally, 0.2 and 0.02 mg/m/sup 3/. Individual PAH concentrations were 0.03-0.05 and 0.003-0.005 mg/m/sup 3/, respectively.

  6. Asthmatic responses to airborne acid aerosols

    SciTech Connect

    Ostro, B.D.; Lipsett, M.J.; Wiener, M.B.; Selner, J.C. )

    1991-06-01

    Controlled exposure studies suggest that asthmatics may be more sensitive to the respiratory effects of acidic aerosols than individuals without asthma. This study investigates whether acidic aerosols and other air pollutants are associated with respiratory symptoms in free-living asthmatics. Daily concentrations of hydrogen ion (H+), nitric acid, fine particulates, sulfates and nitrates were obtained during an intensive air monitoring effort in Denver, Colorado, in the winter of 1987-88. A panel of 207 asthmatics recorded respiratory symptoms, frequency of medication use, and related information in daily diaries. We used a multiple regression time-series model to analyze which air pollutants, if any, were associated with health outcomes reported by study participants. Airborne H+ was found to be significantly associated with several indicators of asthma status, including moderate or severe cough and shortness of breath. Cough was also associated with fine particulates, and shortness of breath with sulfates. Incorporating the participants' time spent outside and exercise intensity into the daily measure of exposure strengthened the association between these pollutants and asthmatic symptoms. Nitric acid and nitrates were not significantly associated with any respiratory symptom analyzed. In this population of asthmatics, several outdoor air pollutants, particularly airborne acidity, were associated with daily respiratory symptoms.

  7. Galvanic zinc-copper microparticles inhibit melanogenesis via multiple pigmentary pathways.

    PubMed

    Won, Yen-Kim; Lin, Connie B; Seiberg, Miri; Chen, Nannan; Hu, Yaping; Rossetti, Dianne; Saliou, Claude; Loy, Chong-Jin

    2014-01-01

    The endogenous electrical field of human skin plays an important role in many skin functions. However, the biological effects and mechanism of action of externally applied electrical stimulation on skin remain unclear. Recent study showed that galvanic zinc-copper microparticles produce electrical stimulation and reduce inflammatory and immune responses in intact skin, suggesting the important role of electrical stimulation in non-wounded skin. The objective of this study is to investigate the biological effect of galvanic zinc-copper microparticles on skin pigmentation. Our findings showed that galvanic zinc-copper microparticles inhibited melanogenesis in a human melanoma cell line (MNT-1), human keratinocytes and melanoma cells co-cultures, and in pigmented epidermal equivalents. Treatment of galvanic zinc-copper microparticles inhibited melanogenesis by reducing the promoter transactivation of tyrosinase and tyrosinase-related protein-1 in human melanoma cells. In a co-culture Transwell system of keratinocytes and melanoma cells, galvanic zinc-copper microparticles reduced melanin production via downregulation of endothelin-1 secretion from keratinocytes and reduced tyrosinase gene expression in melanoma cells. In addition, exposure of pigmented epidermal equivalents to galvanic zinc-copper microparticles resulted in reduced melanin deposition. In conclusion, our data demonstrated for the first time that galvanic zinc-copper microparticles reduced melanogenesis in melanoma cells and melanin deposition in pigmented epidermal equivalents by affecting multiple pigmentary pathways. PMID:23700242

  8. Galvanic zinc-copper microparticles inhibit melanogenesis via multiple pigmentary pathways.

    PubMed

    Won, Yen-Kim; Lin, Connie B; Seiberg, Miri; Chen, Nannan; Hu, Yaping; Rossetti, Dianne; Saliou, Claude; Loy, Chong-Jin

    2014-01-01

    The endogenous electrical field of human skin plays an important role in many skin functions. However, the biological effects and mechanism of action of externally applied electrical stimulation on skin remain unclear. Recent study showed that galvanic zinc-copper microparticles produce electrical stimulation and reduce inflammatory and immune responses in intact skin, suggesting the important role of electrical stimulation in non-wounded skin. The objective of this study is to investigate the biological effect of galvanic zinc-copper microparticles on skin pigmentation. Our findings showed that galvanic zinc-copper microparticles inhibited melanogenesis in a human melanoma cell line (MNT-1), human keratinocytes and melanoma cells co-cultures, and in pigmented epidermal equivalents. Treatment of galvanic zinc-copper microparticles inhibited melanogenesis by reducing the promoter transactivation of tyrosinase and tyrosinase-related protein-1 in human melanoma cells. In a co-culture Transwell system of keratinocytes and melanoma cells, galvanic zinc-copper microparticles reduced melanin production via downregulation of endothelin-1 secretion from keratinocytes and reduced tyrosinase gene expression in melanoma cells. In addition, exposure of pigmented epidermal equivalents to galvanic zinc-copper microparticles resulted in reduced melanin deposition. In conclusion, our data demonstrated for the first time that galvanic zinc-copper microparticles reduced melanogenesis in melanoma cells and melanin deposition in pigmented epidermal equivalents by affecting multiple pigmentary pathways.

  9. Proteomic Analysis of Serum Opsonins Impacting Biodistribution and Cellular Association of Porous Silicon Microparticles

    PubMed Central

    Serda, Rita E.; Blanco, Elvin; Mack, Aaron; Stafford, Susan J.; Amra, Sarah; Li, Qingpo; van de Ven, Anne L.; Tanaka, Takemi; Torchilin, Vladimir P.; Wiktorowicz, John E.; Ferrari, Mauro

    2014-01-01

    Mass transport of drug delivery vehicles is guided by particle properties, such as shape, composition and surface chemistry, as well as biomolecules and serum proteins that adsorb to the particle surface. In an attempt to identify serum proteins influencing cellular associations and biodistribution of intravascularly injected particles, we used two dimensional gel electrophoresis and mass spectrometry to identify proteins eluted from the surface of cationic and anionic silicon microparticles. Cationic microparticles displayed a 25-fold greater abundance of Ig light chain variable region, fibrinogen, and complement component 1 compared to their anionic counterparts. The anionic-surface favored equal accumulation of microparticles in the liver and spleen, while cationic-surfaces favored preferential accumulation in the spleen. Immunohistochemistry supported macrophage internalization of both anionic and cationic silicon microparticles in the liver, as well as evidence of association of cationic microparticles with hepatic endothelial cells. Furthermore, scanning electron micrographs supported cellular competition for cationic microparticles by endothelial cells and macrophages. Despite high macrophage content in the lungs and tumor, microparticle uptake by these cells was minimal, supporting differences in the repertoire of surface receptors expressed by tissue-specific macrophages. In summary, particle surface chemistry drives selective binding of serum components impacting cellular interactions and biodistribution. PMID:21303614

  10. Pirfenidone inhibits p38-mediated generation of procoagulant microparticles by human alveolar epithelial cells.

    PubMed

    Neri, Tommaso; Lombardi, Stefania; Faìta, Francesca; Petrini, Silvia; Balìa, Cristina; Scalise, Valentina; Pedrinelli, Roberto; Paggiaro, Pierluigi; Celi, Alessandro

    2016-08-01

    Pirfenidone is a drug recently approved for idiopathic pulmonary fibrosis but its mechanisms of action are partially unknown. We have previously demonstrated that the airways of patients with idiopathic pulmonary fibrosis contain procoagulant microparticles that activate coagulation factor X to its active form, Xa, a proteinase that signals fibroblast growth and differentiation, thus potentially contributing to the pathogenesis of the disease. We also reported that in vitro exposure of human alveolar cells to H2O2 causes microparticle generation. Since p38 activation is involved in microparticle generation in some cell models and p38 inhibition is one of the mechanisms of action of pirfenidone, we investigated the hypothesis that H2O2-induced generation of microparticles by alveolar cells is dependent on p38 phosphorylation and is inhibited by pirfenidone. H2O2 stimulation of alveolar cells caused p38 phosphorylation that was inhibited by pirfenidone. The drug also inhibited H2O2 induced microparticle generation as assessed by two independent methods (solid phase thrombin generation and flow cytometry). The shedding of microparticle-bound tissue factor activity was also inhibited by pirfenidone. Inhibition of p38-mediated generation of procoagulant microparticle is a previously unrecognized mechanism of action of the antifibrotic drug, pirfenidone. PMID:27237042

  11. Controlled release behaviour of protein-loaded microparticles prepared via coaxial or emulsion electrospray

    PubMed Central

    Wang, Ying; Yang, Xiaoping; Liu, Wentao; Zhang, Feng; Cai, Qing; Deng, Xuliang

    2013-01-01

    Biodegradable poly (lactic-co-glycolic acid) (PLGA) microparticles are an effective way to achieve sustained drug release. In this study, we investigated a sustained release model of PLGA microparticles with incorporated protein via either emulsion or coaxial electrospray techniques. PLGA (75:25) was used as the carrier, and bovine serum albumin as a model protein. Coaxial electrospray resulted in a type of core–shell structure with mean diameters of 2.41 ± 0.60 µm and a centralised protein distribution within the core. Emulsion electrospray formed bigger microparticles with mean diameters of 22.75 ± 8.05 µm and a heterogeneous protein distribution throughout the microparticles. The coaxial electrospray microparticles presented a much slighter burst release than the emulsion electrospray microparticles. Loading efficiency was significantly higher (p < 0.05) in the coaxial group than emulsion group. This indicated that both emulsion and coaxial electrospray could produce protein-loaded microparticles with sustained release behaviour, but the former revealed a superior approach for drug delivery. PMID:23346923

  12. Targeted transfollicular delivery of artocarpin extract from Artocarpus incisus by means of microparticles.

    PubMed

    Pitaksuteepong, Tasana; Somsiri, Atawit; Waranuch, Neti

    2007-11-01

    Artocarpin (Ar), an extract of heartwood of Artocarpus incisus, possesses potent 5alpha reductase inhibitory effect. The penetration of Ar into the deeper layers of the skin where androgen receptors are present is limited. Therefore, this study was aimed to prepare alginate/chitosan (ACS) microparticles for targeted transfollicular delivery. It was found that a suitable particle size ranging from 2 to 6 microm can be prepared using the ionotropic gelation technique. Entrapment efficiency of Ar in ACS microparticles was 18.7+/-1.7%. The release of Ar from the ACS microparticles over 6 h was 0.7% of the loading dose suitable for a long-term release of Ar in the follicular ducts. The optimal growth suppression of the hamster flank organs could be achieved by topical application of Ar-ACS microparticles with a content of 0.1 mg in 5 mg microparticles to one hamster flank while the other flank (intraspecies control) showed the normal growth of the flank organs and Ar at the same concentration in solution form could not suppress the growth of the flank organs to the same extent. The efficiency of Ar 0.1 mg loaded in ACS microparticles was shown to be comparable to a dose of 1 mg Ar applied as solution. However, Ar formulated in microparticles did not show significant systemic action compared to the dermal application of an Ar solution and a flutamide preparation (1 mg) as positive control.

  13. Preparation and characterization of alginate and alginate-resistant starch microparticles containing nisin.

    PubMed

    Hosseini, Seyede Marzieh; Hosseini, Hedayat; Mohammadifar, Mohammad Amin; German, J Bruce; Mortazavian, Amir Mohammad; Mohammadi, Abdorreza; Khosravi-Darani, Kianoosh; Shojaee-Aliabadi, Saeedeh; Khaksar, Ramin

    2014-03-15

    Delivery systems with sustained release of nisin have been proposed to improve stability and long-term effectiveness of this bacteriocin in foods. In this study, nisin was encapsulated in alginate (Alg) and alginate-resistant starch (Alg-RS) microparticles and its release was investigated. Studies found that the nisin concentration has significant influence on encapsulation efficiency (EE), loading capacity (LC) and size of both microparticles. Furthermore, encapsulation efficiency and loading capacity values were more increased by the addition of resistant starch to the alginate formulation. The highest encapsulation efficiency was obtained with Alg-RS microparticles prepared using initial nisin to alginate weight ratio of 25% w/w (59.77 ± 2.26%). Fourier transform-infrared (FT-IR) spectroscopy, X-ray diffraction (XRD) and differential scanning calorimetry (DSC) results confirmed the presence of nisin in the microparticles. The in vitro nisin release from these microparticles followed a controlled-release pattern consistent with a Fickian diffusion mechanism. The release rate from Alg-RS microparticles was less than that from the Alg microparticles.

  14. NASA Airborne Lidar 1982-1984 Flights

    Atmospheric Science Data Center

    2016-05-26

    NASA Airborne Lidar 1982-1984 Flights Data from the 1982 NASA Langley Airborne Lidar flights following the eruption of El Chichon ... continuing to January 1984. Transcribed from the following NASA Tech Reports: McCormick, M. P., and M. T. Osborn, Airborne lidar ...

  15. Controlled motion of electrically neutral microparticles by pulsed direct current

    PubMed Central

    Zhang, Xinfang; Qin, Rongshan

    2015-01-01

    A controlled motion of electrically neutral microparticles in a conductive liquid at high temperatures has not yet been realized under the uniform direct electric current field. We propose a simple method, which employs pulsed direct current to a conductive liquid metal containing low-conductivity objects at high temperature. The electric current enables the low-conductivity particles to pass from the centre towards the various surfaces of the high-conductivity liquid metal. Most interestingly, the directionality of microparticles can be controlled and their speed can be easily regulated by adjusting pulsed current density. We find that the movement may arise from the configuration of electrical domains which generates a driving force which exceeds the force of gravity and viscous friction. All of these features are of potential benefit in separating the particles of nearly equal density but distinctly different electrical conductivities, and also offer considerable promise for the precise and selective positioning of micro-objects or the controlled motion of minute quantities of surrounding fluids. PMID:25955864

  16. Immobilized Particle Imaging for Quantification of Nano- and Microparticles.

    PubMed

    Cui, Jiwei; Hibbs, Benjamin; Gunawan, Sylvia T; Braunger, Julia A; Chen, Xi; Richardson, Joseph J; Hanssen, Eric; Caruso, Frank

    2016-04-12

    The quantification of nano- and microparticles is critical for diverse applications relying on the exact knowledge of the particle concentration. Although many techniques are available for counting particles, there are some limitations in regards to counting with low-scattering materials and facile counting in harsh organic solvents. Herein, we introduce an easy and rapid particle counting technique, termed "immobilized particle imaging" (IPI), to quantify fluorescent particles with different compositions (i.e., inorganic or organic), structures (i.e., solid, porous, or hollow), and sizes (50-1000 nm) dispersed in either aqueous or organic solutions. IPI is achieved by immobilizing particles of interest in a cell matrix-like scaffold (e.g., agarose) and imaging using standard microscopy techniques. Imaging a defined volume of the immobilized particles allows for the particle concentration to be calculated from the count numbers in a fixed volume. IPI provides a general and facile approach to quantify advanced nano- and microparticles, which may be helpful to researchers to obtain new insights for different applications (e.g., nanomedicine).

  17. Cytotoxicity assessment of porous silicon microparticles for ocular drug delivery.

    PubMed

    Korhonen, Eveliina; Rönkkö, Seppo; Hillebrand, Satu; Riikonen, Joakim; Xu, Wujun; Järvinen, Kristiina; Lehto, Vesa-Pekka; Kauppinen, Anu

    2016-03-01

    Porous silicon (PSi) is a promising material for the delivery and sustained release of therapeutic molecules in various tissues. Due to the constant rinsing of cornea by tear solution as well as the short half-life of intravitreal drugs, the eye is an attractive target for controlled drug delivery systems, such as PSi microparticles. Inherent barriers ensure that PSi particles are retained in the eye, releasing drugs at the desired speed until they slowly break down into harmless silicic acid. Here, we have examined the in vitro cytotoxicity of positively and negatively charged thermally oxidized (TOPSi) and thermally carbonized (TCPSi) porous silicon microparticles on human corneal epithelial (HCE) and retinal pigment epithelial (ARPE-19) cells. In addition to ocular assessment under an inverted microscope, cellular viability was evaluated using the CellTiter Blue™, CellTiter Fluor™, and lactate dehydrogenase (LDH) assays. CellTiter Fluor proved to be a suitable assay but due to non-specific and interfering responses, neither CellTiter Blue nor LDH assays should be used when evaluating PSi particles. Our results suggest that the toxicity of PSi particles is concentration-dependent, but at least at concentrations less than 200μg/ml, both positively and negatively charged PSi particles are well tolerated by human corneal and retinal epithelial cells and therefore applicable for delivering drug molecules into ocular tissues.

  18. Platelet microparticles promote neural stem cell proliferation, survival and differentiation.

    PubMed

    Hayon, Yael; Dashevsky, Olga; Shai, Ela; Varon, David; Leker, Ronen R

    2012-07-01

    Platelet microparticles (PMP) are small subcellular fragments, shed upon platelet activation. PMP host a variety of cytokines and growth factor that were previously shown to affect angiogenesis and postischemic tissue regeneration. This study attempted to explore the effect of PMP on neural stem cell (NSC) proliferation, survival and differentiation. Cells were grown as neurospheres and treated with PMP, or relevant growth factors, sphere size and cell fates were evaluated. PMP treatment led to larger neurospheres with increased cell survival. PMP treatment was comparable with the effect of acceptable single growth factors such as fibroblastic growth factor (FGF), vascular endothelial growth factor (VEGF) and platelet derived growth factor (PDGF). PMP treatment also increased the differentiation potential of NSC to glia and neurons. Specific growth factor inhibitors only partly blocked these effects, which were associated with increments in ERK and Akt phosphorylation. In this study, we show that various growth factors contained within the PMP promote neuronal cell proliferation, survival and differentiation. The results suggest a role for platelet microparticles in augmenting endogenous neural progenitor and stem cells angiogenesis and neurogenesis that might be utilized for treatment following brain injury.

  19. A stochastic DNA walker that traverses a microparticle surface

    PubMed Central

    Jung, C.; Allen, P. B.; Ellington, A. D.

    2015-01-01

    Molecular machines have previously been designed that are propelled by DNAzymes1–3, protein enzymes4–6 and strand-displacement7–9. These engineered machines typically move along precisely defined one- and two-dimensional tracks. Here, we report a DNA walker that uses hybridisation to drive walking on DNA-coated microparticle surfaces. Through purely DNA:DNA hybridisation reactions, the nanoscale movements of the walker can lead to the generation of a single-stranded product and the subsequent immobilisation of fluorescent labels on the microparticle surface. This suggests that the system could be of use in analytical and diagnostic applications, similar to how strand exchange reactions in solution have been used for transducing and quantifying signals from isothermal molecular amplification assays10,11. The walking behaviour is robust and the walker can take more than 30 continuous steps. The traversal of an unprogrammed, inhomogeneous surface is also due entirely to autonomous decisions made by the walker, behaviour analogous to amorphous chemical reaction network computations12,13 that have been shown to lead to pattern formation14–17. PMID:26524397

  20. Excipient-free nanoporous microparticles of budesonide for pulmonary delivery.

    PubMed

    Nolan, Lorraine M; Tajber, Lidia; McDonald, Bernard F; Barham, Ahmad S; Corrigan, Owen I; Healy, Anne Marie

    2009-07-12

    The aim of this study was to investigate the application of a spray-drying process for the production of nanoporous microparticles (NPMPs) to budesonide, and to characterise the particles produced in terms of their suitability for pulmonary delivery. Budesonide was spray dried with and without ammonium carbonate from ethanol/water or methanol/water solutions. The solid-state characteristics and micromeritic (particle size, density, surface area) properties of spray dried powders were assessed. In vitro deposition studies were performed to assess aerosol performance. The densities of the NPMPs were significantly lower and the surface areas significantly higher than for non-porous spray dried or micronised material. NPMPs of budesonide demonstrated improved aerosolisation properties compared to spray dried non-porous, micronised material and two budesonide commercial products. All spray dried materials were amorphous in nature. The glass transition temperature (approximately 90 degrees C) was sufficiently high to suggest good physical stability at room temperature. When stored at 25 degrees C/60% RH NPMPs showed a reduced tendency to recrystallise compared to the equivalent non-porous spray dried powder. The physical stability and amorphous nature of NPMPs was retained, under these storage conditions for at least one year and the in vitro aerosolisation properties were not affected by the storage conditions. Excipient-free porous microparticles, prepared by the novel process described, show good potential for drug delivery by oral inhalation with improved in vitro deposition properties compared to non-porous particles. PMID:19463948

  1. Microparticle of drug and nanoparticle: a biosynthetic route.

    PubMed

    Sarkar, Sounik; Dasgupta, Anjan Kr

    2015-10-01

    Microparticles (MPs) have great potentiality in material science- based applications. Their use in biology is however limited to clinics and has rarely been exploited in the pharmaceutical context. Unlike nanoparticles (NPs), they are amenable to routine detection by flow cytometry and confocal microscopy. Though MPs can constitute a wide variety of materials, including ceramics, glass, polymers, and metals and can be synthesized by chemical process but wet processes for the preparation of microparticles have rarely been attemped. In this paper, a thrombotic route is shown to successfully generate biocompatible MP of a model anticancer drug (doxorubicin hydrochloride). Synthesis of MPs from platelets and drug loading in to these MPs was confirmed by flow cytometry and confocal microscopy. Human cervical cancer cell line (HeLa) was treated with these drug-loaded MPs to investigate whether the loaded MPs have the capacity to deliver drug to the cancer cells. In addition, Magnetic force microscopy was used to detect the preparation of MPs loaded with magnetic NPs. The efficiency of the drug-loaded MPs in inducing cytotoxicity in cancer cell line, shown to be significantly higher than the free drug itself. The drug-loaded MP is shown to have a much higher cytotoxic propensity than the free drug applied at comparable doses. The thrombotic approach can also be applied to synthesize MP containing NPs which in turn can lead to generate a wide variety of new biocompatible materials.

  2. Cytotoxicity assessment of porous silicon microparticles for ocular drug delivery.

    PubMed

    Korhonen, Eveliina; Rönkkö, Seppo; Hillebrand, Satu; Riikonen, Joakim; Xu, Wujun; Järvinen, Kristiina; Lehto, Vesa-Pekka; Kauppinen, Anu

    2016-03-01

    Porous silicon (PSi) is a promising material for the delivery and sustained release of therapeutic molecules in various tissues. Due to the constant rinsing of cornea by tear solution as well as the short half-life of intravitreal drugs, the eye is an attractive target for controlled drug delivery systems, such as PSi microparticles. Inherent barriers ensure that PSi particles are retained in the eye, releasing drugs at the desired speed until they slowly break down into harmless silicic acid. Here, we have examined the in vitro cytotoxicity of positively and negatively charged thermally oxidized (TOPSi) and thermally carbonized (TCPSi) porous silicon microparticles on human corneal epithelial (HCE) and retinal pigment epithelial (ARPE-19) cells. In addition to ocular assessment under an inverted microscope, cellular viability was evaluated using the CellTiter Blue™, CellTiter Fluor™, and lactate dehydrogenase (LDH) assays. CellTiter Fluor proved to be a suitable assay but due to non-specific and interfering responses, neither CellTiter Blue nor LDH assays should be used when evaluating PSi particles. Our results suggest that the toxicity of PSi particles is concentration-dependent, but at least at concentrations less than 200μg/ml, both positively and negatively charged PSi particles are well tolerated by human corneal and retinal epithelial cells and therefore applicable for delivering drug molecules into ocular tissues. PMID:26686646

  3. A stochastic DNA walker that traverses a microparticle surface.

    PubMed

    Jung, C; Allen, P B; Ellington, A D

    2016-02-01

    Molecular machines have previously been designed that are propelled by DNAzymes, protein enzymes and strand displacement. These engineered machines typically move along precisely defined one- and two-dimensional tracks. Here, we report a DNA walker that uses hybridization to drive walking on DNA-coated microparticle surfaces. Through purely DNA:DNA hybridization reactions, the nanoscale movements of the walker can lead to the generation of a single-stranded product and the subsequent immobilization of fluorescent labels on the microparticle surface. This suggests that the system could be of use in analytical and diagnostic applications, similar to how strand exchange reactions in solution have been used for transducing and quantifying signals from isothermal molecular amplification assays. The walking behaviour is robust and the walker can take more than 30 continuous steps. The traversal of an unprogrammed, inhomogeneous surface is also due entirely to autonomous decisions made by the walker, behaviour analogous to amorphous chemical reaction network computations, which have been shown to lead to pattern formation. PMID:26524397

  4. Controlled Release Pulmonary Administration of Curcumin Using Swellable Biocompatible Microparticles

    PubMed Central

    El-Sherbiny, Ibrahim M.; Smyth, Hugh D. C.

    2012-01-01

    This study involves a promising approach to achieve sustained pulmonary drug delivery. Dry powder particulate carriers were engineered to allow simultaneous aerosol lung delivery, evasion of macrophage uptake, and sustained drug release through a controlled polymeric architecture. Chitosan grafted with PEG was synthesized and characterized (FTIR, EA, DSC and 2D-XRD). Then, a series of respirable amphiphilic hydrogel microparticles were developed via spray drying of curcumin-loaded PLGA nanoparticles with chitosan-grafted-PEG or chitosan. The nano and microparticles were fully characterized using an array of physicochemical analytical methods including particle size, surface morphology, dynamic swelling, density, moisture content and biodegradation rates. The PLGA nanoparticles and the hydrogel microspheres encapsulating the curcumin-loaded PLGA nanoparticles showed average size of (221-243 nm) and (3.1-3.9 μm), respectively. The developed carriers attained high swelling within a few minutes, showed low moisture content as dry powders (0.9-1.8%), desirable biodegradation rates, high drug loading (up to 97%), and good sustained release. An aerosolization study was conducted using a next generation impactor and promising aerosolization characteristics were shown. In vitro macrophage uptake studies, cytotoxicity and in-vitro TNF-α assays were performed for the investigated particles. These assays revealed promising bio-interactions for the respirable/swellable nano-micro particles developed in this study as potential carriers for sustained pulmonary drug delivery. PMID:22136259

  5. Composite microparticles of halloysite clay nanotubes bound by calcium carbonate.

    PubMed

    Jin, Yi; Yendluri, Raghuvara; Chen, Bin; Wang, Jingbo; Lvov, Yuri

    2016-03-15

    Natural halloysite clay nanotubes with 15 nm inner and 75 nm outer diameters have been used as vehicles for sustained release of drugs in composite hollow microparticles "glued" with CaCO3. We used a layer-by layer assembly accomplished alginate binding with Ca(2+) followed by CO2 bubbling to prepare the composite microspheres of CaCO3 and polyelectrolytes (PE) modified halloysite nanotubes (HNTs-PE2/CaCO3) with the diameter of about 5-10 μm. These microparticles have empty spherical structure and abundant pore distributions with maxima at 2.5, 3.9, 6.0 and 13.3 nm, and higher surface area of 82.3 m(2) g(-1) as characterized by SEM and BET test. We loaded drugs in these micro-nano carriers of tight piles of halloysite nanotube with end clogged with CaCO3. The sustained release of Nifedipine drug from HNTs-PE2/CaCO3 composite microspheres was slower than for pristine halloysite nanotubes. PMID:26745741

  6. Composite microparticles of halloysite clay nanotubes bound by calcium carbonate.

    PubMed

    Jin, Yi; Yendluri, Raghuvara; Chen, Bin; Wang, Jingbo; Lvov, Yuri

    2016-03-15

    Natural halloysite clay nanotubes with 15 nm inner and 75 nm outer diameters have been used as vehicles for sustained release of drugs in composite hollow microparticles "glued" with CaCO3. We used a layer-by layer assembly accomplished alginate binding with Ca(2+) followed by CO2 bubbling to prepare the composite microspheres of CaCO3 and polyelectrolytes (PE) modified halloysite nanotubes (HNTs-PE2/CaCO3) with the diameter of about 5-10 μm. These microparticles have empty spherical structure and abundant pore distributions with maxima at 2.5, 3.9, 6.0 and 13.3 nm, and higher surface area of 82.3 m(2) g(-1) as characterized by SEM and BET test. We loaded drugs in these micro-nano carriers of tight piles of halloysite nanotube with end clogged with CaCO3. The sustained release of Nifedipine drug from HNTs-PE2/CaCO3 composite microspheres was slower than for pristine halloysite nanotubes.

  7. Accelerating protein release from microparticles for regenerative medicine applications

    PubMed Central

    White, Lisa J.; Kirby, Giles T.S.; Cox, Helen C.; Qodratnama, Roozbeh; Qutachi, Omar; Rose, Felicity R.A.J.; Shakesheff, Kevin M.

    2013-01-01

    There is a need to control the spatio-temporal release kinetics of growth factors in order to mitigate current usage of high doses. A novel delivery system, capable of providing both structural support and controlled release kinetics, has been developed from PLGA microparticles. The inclusion of a hydrophilic PLGA–PEG–PLGA triblock copolymer altered release kinetics such that they were decoupled from polymer degradation. A quasi zero order release profile over four weeks was produced using 10% w/w PLGA–PEG–PLGA with 50:50 PLGA whereas complete and sustained release was achieved over ten days using 30% w/w PLGA–PEG–PLGA with 85:15 PLGA and over four days using 30% w/w PLGA–PEG–PLGA with 50:50 PLGA. These three formulations are promising candidates for delivery of growth factors such as BMP-2, PDGF and VEGF. Release profiles were also modified by mixing microparticles of two different formulations providing another route, not previously reported, for controlling release kinetics. This system provides customisable, localised and controlled delivery with adjustable release profiles, which will improve the efficacy and safety of recombinant growth factor delivery. PMID:23623071

  8. Circulating Endothelial Microparticles: A Key Hallmark of Atherosclerosis Progression

    PubMed Central

    Panth, Nisha; Kim, Dong-Wook

    2016-01-01

    The levels of circulating microparticles (MPs) are raised in various cardiovascular diseases. Their increased level in plasma is regarded as a biomarker of alteration in vascular function. The prominent MPs present in blood are endothelial microparticles (EMPs) described as complex submicron (0.1 to 1.0 μm) vesicles like structure, released in response to endothelium cell activation or apoptosis. EMPs possess both physiological and pathological effects and may promote oxidative stress and vascular inflammation. EMPs release is triggered by inducer like angiotensin II, lipopolysaccharide, and hydrogen peroxide leading to the progression of atherosclerosis. However, there are multiple physiological pathways for EMPs generation like NADPH oxidase derived endothelial ROS formation, Rho kinase pathway, and mitogen-activated protein kinases. Endothelial dysfunction is a key initiating event in atherosclerotic plaque formation. Atheroemboli, resulting from ruptured carotid plaques, is a major cause of stroke. Increasing evidence suggests that EMPs play an important role in the pathogenesis of cardiovascular disease, acting as a marker of damage, either exacerbating disease progression or triggering a repair response. In this regard, it has been suggested that EMPs have the potential to act as biomarkers of disease status. This review aims to provide updated information of EMPs in relation to atherosclerosis pathogenesis. PMID:27066292

  9. The preservation of living cells with biocompatible microparticles

    NASA Astrophysics Data System (ADS)

    Yang, Jing; Zhu, Yingnan; Xu, Tong; Pan, Chao; Cai, Nana; Huang, He; Zhang, Lei

    2016-07-01

    Biomedical applications of living cells have rapidly expanded in many fields such as toxic detection, drug screening, and regenerative medicine, etc. Efficient methods to support cell survival and maintain activity in vitro have become increasingly important. However, traditional cryopreservation for living cell-based applications is limited by several problems. Here, we report that magnetic hydrogel microparticles can physically assemble into a 3D environment for efficient cell preservation in physiological conditions, avoiding any chemical reactions that would damage the cells. Two representative cell lines (loosely and firmly adherent) were tested to evaluate the versatility of this method. The results showed that cell longevity was significantly extended to at least 15 days, while the control cell samples without microparticles quickly died within 3 days. Moreover, after preservation, cells can be easily retrieved by applying a magnet to separate the magnetic particles. This strategy can also inhibit cell over-proliferation while avoiding the use of temperature extremes or toxic cryoprotectants that are essential in cryopreservation.

  10. The preservation of living cells with biocompatible microparticles.

    PubMed

    Yang, Jing; Zhu, Yingnan; Xu, Tong; Pan, Chao; Cai, Nana; Huang, He; Zhang, Lei

    2016-07-01

    Biomedical applications of living cells have rapidly expanded in many fields such as toxic detection, drug screening, and regenerative medicine, etc. Efficient methods to support cell survival and maintain activity in vitro have become increasingly important. However, traditional cryopreservation for living cell-based applications is limited by several problems. Here, we report that magnetic hydrogel microparticles can physically assemble into a 3D environment for efficient cell preservation in physiological conditions, avoiding any chemical reactions that would damage the cells. Two representative cell lines (loosely and firmly adherent) were tested to evaluate the versatility of this method. The results showed that cell longevity was significantly extended to at least 15 days, while the control cell samples without microparticles quickly died within 3 days. Moreover, after preservation, cells can be easily retrieved by applying a magnet to separate the magnetic particles. This strategy can also inhibit cell over-proliferation while avoiding the use of temperature extremes or toxic cryoprotectants that are essential in cryopreservation. PMID:27189861

  11. Controlled release pulmonary administration of curcumin using swellable biocompatible microparticles.

    PubMed

    El-Sherbiny, Ibrahim M; Smyth, Hugh D C

    2012-02-01

    This study involves a promising approach to achieve sustained pulmonary drug delivery. Dry powder particulate carriers were engineered to allow simultaneous aerosol lung delivery, evasion of macrophage uptake, and sustained drug release through a controlled polymeric architecture. Chitosan grafted with PEG was synthesized and characterized (FTIR, EA, DSC and 2D-XRD). Then, a series of respirable amphiphilic hydrogel microparticles were developed via spray drying of curcumin-loaded PLGA nanoparticles with chitosan-grafted-PEG or chitosan. The nanoparticles and microparticles were fully characterized using an array of physicochemical analytical methods including particle size, surface morphology, dynamic swelling, density, moisture content and biodegradation rates. The PLGA nanoparticles and the hydrogel microspheres encapsulating the curcumin-loaded PLGA nanoparticles showed average size of 221-243 nm and 3.1-3.9 μm, respectively. The developed carriers attained high swelling within a few minutes and showed low moisture content as dry powders (0.9-1.8%), desirable biodegradation rates, high drug loading (up to 97%), and good sustained release. An aerosolization study was conducted using a next generation impactor, and promising aerosolization characteristics were shown. In vitro macrophage uptake studies, cytotoxicity and in vitro TNF-α assays were performed for the investigated particles. These assays revealed promising biointeractions for the respirable/swellable nano-micro particles developed in this study as potential carriers for sustained pulmonary drug delivery. PMID:22136259

  12. Duality of β-glucan microparticles: antigen carrier and immunostimulants

    PubMed Central

    Baert, Kim; De Geest, Bruno G; De Greve, Henri; Cox, Eric; Devriendt, Bert

    2016-01-01

    Designing efficient recombinant mucosal vaccines against enteric diseases is still a major challenge. Mucosal delivery of recombinant vaccines requires encapsulation in potent immunostimulatory particles to induce an efficient immune response. This paper evaluates the capacity of β-glucan microparticles (GPs) as antigen vehicles and characterizes their immune-stimulatory effects. The relevant infectious antigen FedF was chosen to be loaded inside the microparticles. The incorporation of FedF inside the particles was highly efficient (roughly 85%) and occurred without antigen degradation. In addition, these GPs have immunostimulatory effects as well, demonstrated by the strong reactive oxygen species (ROS) production by porcine neutrophils upon their recognition. Although antigen-loaded GPs still induce ROS production, antigen loading decreases this production by neutrophils for reasons yet unknown. However, these antigen-loaded GPs are still able to bind their specific β-glucan receptor, demonstrated by blocking complement receptor 3, which is the major β-glucan receptor on porcine neutrophils. The dual character of these particles is confirmed by a T-cell proliferation assay. FedF-loaded particles induce a significantly higher FedF-specific T-cell proliferation than soluble FedF. Taken together, these results show that GPs are efficient antigen carriers with immune-stimulatory properties. PMID:27330289

  13. Steroid/mucokinetic hybrid nanoporous microparticles for pulmonary drug delivery.

    PubMed

    Tewes, Frederic; Paluch, Krzysztof J; Tajber, Lidia; Gulati, Karan; Kalantri, Devesh; Ehrhardt, Carsten; Healy, Anne Marie

    2013-11-01

    In a number of pulmonary diseases, patients may develop abnormally viscous mucus reducing drug efficacy. To increase budesonide diffusion within lung fluid, we developed nanoporous microparticles (NPMPs) composed of budesonide and a mucokinetic, ambroxol hydrochloride, to be inhaled as a dry powder. Budesonide/ambroxol-HCl particles were formulated by spray drying and characterised by various physicochemicals methods. Aerodynamic properties were evaluated using a cascade impactor. Drugs apparent permeability coefficients were calculated across mucus producing Calu-3 cell monolayers cultivated at an air-liquid interface. Microparticles made only from budesonide and ambroxol-HCl had smooth surfaces. In the presence of ammonium carbonate ((NH4)2CO3), NPMPs were formulated, with significantly (P<0.05) superior aerodynamic properties (MMAD=1.87±0.22 μm and FPF=84.0±2.6%). The formation of nanopores and the increase in the specific surface area in the presence of (NH4)2CO3 were mainly attributed to the neutralisation of ambroxol-HCl to form ambroxol base. Thus, ambroxol base could behave in the same manner as budesonide and prompt nanoprecipitation when spray dried from an ethanol/water mix occurs. All formulations were amorphous, which should enhance dissolution rate and diffusion through lung fluid. These NPMPs were able to improve budesonide permeability across mucus producing Calu-3 cell monolayers (P<0.05) suggesting that they should be able to enhance budesonide diffusion in the lungs through viscous mucus.

  14. Microparticle of drug and nanoparticle: a biosynthetic route

    PubMed Central

    Sarkar, Sounik; Dasgupta, Anjan Kr

    2015-01-01

    Microparticles (MPs) have great potentiality in material science- based applications. Their use in biology is however limited to clinics and has rarely been exploited in the pharmaceutical context. Unlike nanoparticles (NPs), they are amenable to routine detection by flow cytometry and confocal microscopy. Though MPs can constitute a wide variety of materials, including ceramics, glass, polymers, and metals and can be synthesized by chemical process but wet processes for the preparation of microparticles have rarely been attemped. In this paper, a thrombotic route is shown to successfully generate biocompatible MP of a model anticancer drug (doxorubicin hydrochloride). Synthesis of MPs from platelets and drug loading in to these MPs was confirmed by flow cytometry and confocal microscopy. Human cervical cancer cell line (HeLa) was treated with these drug-loaded MPs to investigate whether the loaded MPs have the capacity to deliver drug to the cancer cells. In addition, Magnetic force microscopy was used to detect the preparation of MPs loaded with magnetic NPs. The efficiency of the drug-loaded MPs in inducing cytotoxicity in cancer cell line, shown to be significantly higher than the free drug itself. The drug-loaded MP is shown to have a much higher cytotoxic propensity than the free drug applied at comparable doses. The thrombotic approach can also be applied to synthesize MP containing NPs which in turn can lead to generate a wide variety of new biocompatible materials. PMID:26516592

  15. Geometric Constraints on Planar Manipulation of Microparticles via Magnetic Traps

    NASA Astrophysics Data System (ADS)

    Pierce, C.; Prikockis, M.; Sooryakumar, R.

    2015-03-01

    Recently, thin film based devices have been developed to trap and transport particles via localized magnetic fields and the associated strong gradients found at domain walls in patterned wires. In scaling up the device performance to achieve greater throughput and finer control over the spatial resolution in maneuvering the particles, it is necessary to understand the constraints imposed by the architecture of the wires. Due to shape anisotropy, ferromagnetic microstructures of Co0.5Fe0.5 comprising isolated and connected linear segments acquire stable magnetic domain states when magnetized in an external field. The stray fields in the vicinity of the domain walls, when combined with weak external fields (~ 10 Oe), create sites which controllably attract or repel superparamagnetic micro-particles. The dependence of trap strength on device scale, aspect ratio, geometry and orientation relative to magnetizing field and neighboring sites are investigated through simulation and experiments involving magnetic microparticles of various sizes. Constraints placed on the types of manipulations achievable with this scheme and their implications towards realizing high throughput Lab-on-a-Chip devices will be discussed.

  16. Steroid/mucokinetic hybrid nanoporous microparticles for pulmonary drug delivery.

    PubMed

    Tewes, Frederic; Paluch, Krzysztof J; Tajber, Lidia; Gulati, Karan; Kalantri, Devesh; Ehrhardt, Carsten; Healy, Anne Marie

    2013-11-01

    In a number of pulmonary diseases, patients may develop abnormally viscous mucus reducing drug efficacy. To increase budesonide diffusion within lung fluid, we developed nanoporous microparticles (NPMPs) composed of budesonide and a mucokinetic, ambroxol hydrochloride, to be inhaled as a dry powder. Budesonide/ambroxol-HCl particles were formulated by spray drying and characterised by various physicochemicals methods. Aerodynamic properties were evaluated using a cascade impactor. Drugs apparent permeability coefficients were calculated across mucus producing Calu-3 cell monolayers cultivated at an air-liquid interface. Microparticles made only from budesonide and ambroxol-HCl had smooth surfaces. In the presence of ammonium carbonate ((NH4)2CO3), NPMPs were formulated, with significantly (P<0.05) superior aerodynamic properties (MMAD=1.87±0.22 μm and FPF=84.0±2.6%). The formation of nanopores and the increase in the specific surface area in the presence of (NH4)2CO3 were mainly attributed to the neutralisation of ambroxol-HCl to form ambroxol base. Thus, ambroxol base could behave in the same manner as budesonide and prompt nanoprecipitation when spray dried from an ethanol/water mix occurs. All formulations were amorphous, which should enhance dissolution rate and diffusion through lung fluid. These NPMPs were able to improve budesonide permeability across mucus producing Calu-3 cell monolayers (P<0.05) suggesting that they should be able to enhance budesonide diffusion in the lungs through viscous mucus. PMID:23563102

  17. Phoretic Force Measurement for Microparticles Under Microgravity Conditions

    NASA Technical Reports Server (NTRS)

    Davis, E. J.; Zheng, R.

    1999-01-01

    This theoretical and experimental investigation of the collisional interactions between gas molecules and solid and liquid surfaces of microparticles involves fundamental studies of the transfer of energy, mass and momentum between gas molecules and surfaces. The numerous applications include particle deposition on semiconductor surfaces and on surfaces in combustion processes, containerless processing, the production of nanophase materials, pigments and ceramic precursors, and pollution abatement technologies such as desulfurization of gaseous effluents from combustion processes. Of particular emphasis are the forces exerted on microparticles present in a nonuniform gas, that is, in gaseous surroundings involving temperature and concentration gradients. These so-called phoretic forces become the dominant forces when the gravitational force is diminished, and they are strongly dependent on the momentum transfer between gas molecules and the surface. The momentum transfer, in turn, depends on the gas and particle properties and the mean free path and kinetic energy of the gas molecules. The experimental program involves the particle levitation system shown. A micrometer size particle is held between two heat exchangers enclosed in a vacuum chamber by means of ac and dc electric fields. The ac field keeps the particle centered on the vertical axis of the chamber, and the dc field balances the gravitational force and the thermophoretic force. Some measurements of the thermophoretic force are presented in this paper.

  18. A stochastic DNA walker that traverses a microparticle surface

    NASA Astrophysics Data System (ADS)

    Jung, C.; Allen, P. B.; Ellington, A. D.

    2016-02-01

    Molecular machines have previously been designed that are propelled by DNAzymes, protein enzymes and strand displacement. These engineered machines typically move along precisely defined one- and two-dimensional tracks. Here, we report a DNA walker that uses hybridization to drive walking on DNA-coated microparticle surfaces. Through purely DNA:DNA hybridization reactions, the nanoscale movements of the walker can lead to the generation of a single-stranded product and the subsequent immobilization of fluorescent labels on the microparticle surface. This suggests that the system could be of use in analytical and diagnostic applications, similar to how strand exchange reactions in solution have been used for transducing and quantifying signals from isothermal molecular amplification assays. The walking behaviour is robust and the walker can take more than 30 continuous steps. The traversal of an unprogrammed, inhomogeneous surface is also due entirely to autonomous decisions made by the walker, behaviour analogous to amorphous chemical reaction network computations, which have been shown to lead to pattern formation.

  19. Microparticle Shedding from Neural Progenitor Cells and Vascular Compartment Cells Is Increased in Ischemic Stroke

    PubMed Central

    Chiva-Blanch, Gemma; Suades, Rosa; Crespo, Javier; Peña, Esther; Padró, Teresa; Jiménez-Xarrié, Elena; Martí-Fàbregas, Joan; Badimon, Lina

    2016-01-01

    Purpose Ischemic stroke has shown to induce platelet and endothelial microparticle shedding, but whether stroke induces microparticle shedding from additional blood and vascular compartment cells is unclear. Neural precursor cells have been shown to replace dying neurons at sites of brain injury; however, if neural precursor cell activation is associated to microparticle shedding, and whether this activation is maintained at long term and associates to stroke type and severity remains unknown. We analyzed neural precursor cells and blood and vascular compartment cells microparticle shedding after an acute ischemic stroke. Methods Forty-four patients were included in the study within the first 48h after the onset of stroke. The cerebral lesion size was evaluated at 3–7 days of the stroke. Circulating microparticles from neural precursor cells and blood and vascular compartment cells (platelets, endothelial cells, erythrocytes, leukocytes, lymphocytes, monocytes and smooth muscle cells) were analyzed by flow cytometry at the onset of stroke and at 7 and 90 days. Forty-four age-matched high cardiovascular risk subjects without documented vascular disease were used as controls. Results Compared to high cardiovascular risk controls, patients showed higher number of neural precursor cell- and all blood and vascular compartment cell-derived microparticles at the onset of stroke, and after 7 and 90 days. At 90 days, neural precursor cell-derived microparticles decreased and smooth muscle cell-derived microparticles increased compared to levels at the onset of stroke, but only in those patients with the highest stroke-induced cerebral lesions. Conclusions Stroke increases blood and vascular compartment cell and neural precursor cell microparticle shedding, an effect that is chronically maintained up to 90 days after the ischemic event. These results show that stroke induces a generalized blood and vascular cell activation and the initiation of neuronal cell repair process

  20. Physicomechanical properties of naproxen-loaded microparticles prepared from Eudragit l100.

    PubMed

    Maghsoodi, M

    2009-01-01

    Microparticles of naproxen with Eudragit L100 and Aerosil were prepared by the emulsion solvent diffusion method in order to avoid local gastrointestinal irritation, one of the major side effects of nonsteroidal anti-inflammatory drugs after oral ingestion. The process of preparation involved the use of ethanol as good solvent, dichloromethane as a bridging liquid, water as poor solvent, Aerosil as anti-adhesion agent, and sodium dodecyl sulfate to aid in the dispersion of the drug and excipients into the poor solvent. The obtained microparticles were evaluated for micromeritic properties, yield, encapsulation efficiency, drug physical state, and drug release properties. The influence of formulation factors and preparation condition (polymer/naproxen ratio, Aerosil/polymer ratio, and the initial difference of temperature between the solvent and nonsolvent) on the properties of the microparticles were also examined. The resultant microparticles were finely spherical and uniform with high incorporation efficiency (>79%) and yield (>71%). The incorporation efficiency was enhanced with increasing the ratio of excipients to drug and the initial difference of temperature between the solvent and nonsolvent. The mean diameter of the microparticles was influenced by all of the manufacturing parameters. Studies carried out to characterize the micromeritic properties of formulations, such as flowability and packability, showed that microparticles were suitable for further pharmaceutical manipulation (e.g., capsule filling). Drug release studies of the microparticles confirmed the gastroresistance, and mathematical studies showed that the drug released followed a Hixon and Crowell kinetic. These microparticles represent a simple method for the preparation of drug-loaded enteric microparticles with desired micromeritic properties and gastroresistance release.

  1. In vitro assessment of biopolymer-modified porous silicon microparticles for wound healing applications.

    PubMed

    Mori, Michela; Almeida, Patrick V; Cola, Michela; Anselmi, Giulia; Mäkilä, Ermei; Correia, Alexandra; Salonen, Jarno; Hirvonen, Jouni; Caramella, Carla; Santos, Hélder A

    2014-11-01

    The wound healing stands as very complex and dynamic process, aiming the re-establishment of the damaged tissue's integrity and functionality. Thus, there is an emerging need for developing biopolymer-based composites capable of actively promoting cellular proliferation and reconstituting the extracellular matrix. The aims of the present work were to prepare and characterize biopolymer-functionalized porous silicon (PSi) microparticles, resulting in the development of drug delivery microsystems for future applications in wound healing. Thermally hydrocarbonized PSi (THCPSi) microparticles were coated with both chitosan and a mixture of chondroitin sulfate/hyaluronic acid, and subsequently loaded with two antibacterial model drugs, vancomycin and resveratrol. The biopolymer coating, drug loading degree and drug release behavior of the modified PSi microparticles were evaluated in vitro. The results showed that both the biopolymer coating and drug loading of the THCPSi microparticles were successfully achieved. In addition, a sustained release was observed for both the drugs tested. The viability and proliferation profiles of a fibroblast cell line exposed to the modified THCPSi microparticles and the subsequent reactive oxygen species (ROS) production were also evaluated. The cytotoxicity and proliferation results demonstrated less toxicity for the biopolymer-coated THCPSi microparticles at different concentrations and time points comparatively to the uncoated counterparts. The ROS production by the fibroblasts exposed to both uncoated and biopolymer-coated PSi microparticles showed that the modified PSi microparticles did not induce significant ROS production at the concentrations tested. Overall, the biopolymer-based PSi microparticles developed in this study are promising platforms for wound healing applications.

  2. Early results of microwave transmission experiments through an overly dense rectangular plasma sheet with microparticle injection

    SciTech Connect

    Gillman, Eric D.; Amatucci, W. E.

    2014-06-15

    These experiments utilize a linear hollow cathode to create a dense, rectangular plasma sheet to simulate the plasma layer surrounding vehicles traveling at hypersonic velocities within the Earth's atmosphere. Injection of fine dielectric microparticles significantly reduces the electron density and therefore lowers the electron plasma frequency by binding a significant portion of the bulk free electrons to the relatively massive microparticles. Measurements show that microwave transmission through this previously overly dense, impenetrable plasma layer increases with the injection of alumina microparticles approximately 60 μm in diameter. This method of electron depletion is a potential means of mitigating the radio communications blackout experienced by hypersonic vehicles.

  3. Four-dimensional (4D) tracking of high-temperature microparticles

    NASA Astrophysics Data System (ADS)

    Wang, Zhehui; Liu, Q.; Waganaar, W.; Fontanese, J.; James, D.; Munsat, T.

    2016-11-01

    High-speed tracking of hot and molten microparticles in motion provides rich information about burning plasmas in magnetic fusion. An exploding-wire apparatus is used to produce moving high-temperature metallic microparticles and to develop four-dimensional (4D) or time-resolved 3D particle tracking techniques. The pinhole camera model and algorithms developed for computer vision are used for scene calibration and 4D reconstructions. 3D positions and velocities are then derived for different microparticles. Velocity resolution approaches 0.1 m/s by using the local constant velocity approximation.

  4. Early results of microwave transmission experiments through an overly dense rectangular plasma sheet with microparticle injection

    NASA Astrophysics Data System (ADS)

    Gillman, Eric D.; Amatucci, W. E.

    2014-06-01

    These experiments utilize a linear hollow cathode to create a dense, rectangular plasma sheet to simulate the plasma layer surrounding vehicles traveling at hypersonic velocities within the Earth's atmosphere. Injection of fine dielectric microparticles significantly reduces the electron density and therefore lowers the electron plasma frequency by binding a significant portion of the bulk free electrons to the relatively massive microparticles. Measurements show that microwave transmission through this previously overly dense, impenetrable plasma layer increases with the injection of alumina microparticles approximately 60 μm in diameter. This method of electron depletion is a potential means of mitigating the radio communications blackout experienced by hypersonic vehicles.

  5. Interfacial synthesis of polypyrrole microparticles for effective dissipation of electromagnetic waves

    NASA Astrophysics Data System (ADS)

    Xie, Aming; Jiang, Wanchun; Wu, Fan; Dai, Xiaoqing; Sun, Mengxiao; Wang, Yuan; Wang, Mingyang

    2015-11-01

    A strategy has been adopted to regulate the dielectric properties of polypyrrole microparticles for good electromagnetic absorption performance through an interfacial synthesis process. Classical Debye relaxation theory and resistor-capacitor model have been employed to illustrate the electromagnetic dissipation mechanism of polypyrrole microparticles. The prepared polypyrrole microparticles exhibit an effective electromagnetic absorption bandwidth 5.48 GHz (deeper than -10 dB) from 12.52 to 18 GHz with a filler loading of 15 wt. % in paraffin. It was demonstrated that the morphologies of conducting polymers can significantly affect the dissipation of electromagnetic waves, supplying a strategy for the design of effective electromagnetic absorption materials.

  6. Thermal mechanisms of laser marking in transparent polymers with light-absorbing microparticles

    NASA Astrophysics Data System (ADS)

    Zelenska, K. S.; Zelensky, S. E.; Poperenko, L. V.; Kanev, K.; Mizeikis, V.; Gnatyuk, V. A.

    2016-01-01

    Interaction of highly viscous polystyrene suspensions of light-absorbing microparticles with pulsed radiation of a Q-switched YAG:Nd3+ laser is investigated. Absorption of laser radiation by the suspended microparticles causes thermal decomposition (pyrolysis) of the polymer in the vicinity of the overheated particles. Laser-induced incandescence (LII) of light-absorbing microparticles under irradiation by a sequence of laser pulses is observed. The mechanism of laser marking includes formation of light-absorbing and scattering centers by accumulation of carbonaceous and gaseous products of pyrolysis.

  7. Destruction of monocrystalline silicon with nanosecond pulsed fiber laser accompanied by the oxidation of ablation microparticles

    NASA Astrophysics Data System (ADS)

    Veiko, V. P.; Skvortsov, A. M.; Huynh, C. T.; Petrov, A. A.

    2013-11-01

    In this work, we report an observation of process of local destruction monocrystalline silicon with a scanning beam irradiation of pulse ytterbium fiber laser with a wavelength λ= 1062 nm, accompanied by the oxidation of ablation microparticles. It is shown that depending on the power density of irradiation was observed a large scatter size of the microparticles. From a certain average power density is observed beginning oxidation particulate emitted from the surface of the irradiated area. By varying the parameters of the laser beam such as scanning speed, pulse repetition rate, overlap of laser spot, radiation dose can be achieved almost complete oxidation of all formed during the ablation of microparticles.

  8. Blood circulating microparticle species in relapsing–remitting and secondary progressive multiple sclerosis. A case–control, cross sectional study with conventional MRI and advanced iron content imaging outcomes

    PubMed Central

    Alexander, J.S.; Chervenak, R.; Weinstock-Guttman, B.; Tsunoda, I.; Ramanathan, M.; Martinez, N.E.; Omura, S.; Sato, F.; Chaitanya, G.V.; Minagar, A.; McGee, J.; Jennings, M.H.; Monceaux, C.; Becker, F.; Cvek, U.; Trutschl, M.; Zivadinov, R.

    2015-01-01

    Background Although multiple sclerosis (MS) is thought to represent an excessive and inappropriate immune response to several central nervous system (CNS) autoantigens, increasing evidence also suggests that MS may also be a neurovascular inflammatory disease, characterized by endothelial activation and shedding of cell membrane microdomains known as ‘microparticles’ into the circulation. Objective To investigate the relationships between these endothelial biomarkers and MS. Methods We examined the relative abundance of CD31+/PECAM-1, CD51+CD61+ (αV–β3) and CD54+ (ICAM-1) bearing microparticles in sera of healthy individuals, patients with relapsing–remitting MS, and secondary-progressive MS. We also investigated the correlation among circulating levels of different microparticle species in MS with conventional MRI (T2- and T1-lesion volumes and brain atrophy), as well as novel MR modalities [assessment of iron content on susceptibility-weighted imaging (SWI)-filtered phase]. Results Differences in circulating microparticle levels were found among MS groups, and several microparticle species (CD31+/CD51+/CD61+/CD54+) were found to correlate with conventional MRI and SWI features of MS. Conclusion These results indicate that circulating microparticles’ profiles in MS may support mechanistic roles for microvascular stress and injury which is an underlying contributor not only to MS initiation and progression, but also to pro-inflammatory responses. PMID:26073484

  9. Airborne fungi--a resurvey

    SciTech Connect

    Meyer, G.H.; Prince, H.E.; Raymer, W.J.

    1983-07-01

    A 15-month survey of airborne fungi at 14 geographical stations was conducted to determine the incidence of different fungal genera. Five of these stations were surveyed 25 years earlier. A comparison between previous studies and present surveys revealed similar organisms at each station with slight shifts in frequency of dominant genera.

  10. Tropospheric and Airborne Emission Spectrometers

    NASA Technical Reports Server (NTRS)

    Glavich, Thomas; Beer, Reinhard

    1996-01-01

    X This paper describes the development of two related instruments, the Tropospheric Emission Spectrometer (TES) and the Airborne Emission Spectrometer (AES). Both instruments are infrared imaging Fourier Transform Spectrometers, used for measuring the state of the lower atmosphere, and in particular the measurement of ozone and ozone sources and sinks.

  11. Airborne chemicals and forest health

    SciTech Connect

    Woodman, J.N.; Cowling, E.B.

    1987-02-01

    Over the past few years the possible contribution of acid rain to the problem of forest decline has been a cause of increasing public concern. Research has begun to determine whether airborne chemicals are causing or contributing to visible damage and mortality in eastern spruce-fir and sugar maple forests and to changes in tree growth, usually without visible symptoms, in other parts of North America. This paper describes some of the complex biological relationships that determine health and productivity of forests and that make it difficult to distinguish effects of airborne chemicals from effects of natural stress. It describes four major research approaches for assessment of the effects of airborne chemicals on forests, and it summarizes current understanding of the known and possible effects of airborne chemicals on forest trees in North America and Europe. It also briefly describes the major air quality and forest health research programs in North America, and it assesses how ell these programs are likely to meet information needs during the coming decade. 69 references, 2 figures, 1 table.

  12. Airborne asbestos in public buildings

    SciTech Connect

    Chesson, J.; Hatfield, J.; Schultz, B.; Dutrow, E.; Blake, J. )

    1990-02-01

    The U.S. Environmental Protection Agency sampled air in 49 government-owned buildings (six buildings with no asbestos-containing material, six buildings with asbestos-containing material in generally good condition, and 37 buildings with damaged asbestos-containing material). This is the most comprehensive study to date of airborne asbestos levels in U.S. public buildings during normal building activities. The air outside each building was also sampled. Air samples were analyzed by transmission electron microscopy using a direct transfer preparation technique. The results show an increasing trend in average airborne asbestos levels; outdoor levels are lowest and levels in buildings with damaged asbestos-containing material are highest. However, the measured levels and the differences between indoors and outdoors and between building categories are small in absolute magnitude. Comparable studies from Canada and the UK, although differing in their estimated concentrations, also conclude that while airborne asbestos levels may be elevated in buildings that contain asbestos, levels are generally low. This conclusion does not eliminate the possibility of higher airborne asbestos levels during maintenance or renovation that disturbs the asbestos-containing material.

  13. Multiplexed Detection of Epigenetic Markers Using Quantum Dot (QD)-Encoded Hydrogel Microparticles.

    PubMed

    Yeom, Sang Yun; Son, Choong Hyun; Kim, Byung Sun; Tag, Sung Hyun; Nam, Eunjoo; Shin, Hyogeun; Kim, So Hyun; Gang, Haemin; Lee, Hyunjoo J; Choi, Jungkyu; Im, Heh-In; Cho, Il-Joo; Choi, Nakwon

    2016-04-19

    Epigenetic alterations in gene expression are influenced by experiences and environment, resulting in significant variation of epigenetic markers from individual to individual. Therefore, it is imperative to measure various epigenetic markers simultaneously from samples of individual subjects to accurately analyze the epigenetic markers in biological samples. Moreover, the individualized genome-wide analysis has become a critical technology for recent trends in clinical applications such as early diagnosis and personalized medicine screening of numerous diseases. The array-based detection of modified histones, conventionally used for multiplexed analysis of epigenetic changes, requires pooling of samples from many subjects to analyze population-wise differences in the expression of histone markers and does not permit individualized analysis. Here, we report multiplexed detection of genome-wide changes in various histone modifications at a single-residue resolution using quantum dot (QD)-encoded polyethylene glycol diacrylate (PEGDA) hydrogel microparticles. To demonstrate the potential of our methodology, we present the simultaneous detection of (1) acetylation of lysine 9 of histone 3 (Ac-H3K9), (2) dimethylation of H3K9 (2Me-H3K9), and (3) trimethylation of H3K9 (3Me-H3K9) from three distinct regions in the brain [nucleus accumbens (NAc), dorsal striatum (DSt), and cerebellum (Cbl)] of cocaine-exposed mice. Our hydrogel-based epigenetic assay enabled relative quantification of the three histone variants from only 10 μL of each brain lysate (protein content = ∼ 1 μg/μL) per mouse. We verified that the exposure to cocaine induced a significant increase of acetylation while a notable decrease in methylation in NAc. PMID:26974493

  14. Fourth Airborne Geoscience Workshop: Summary Minutes

    NASA Technical Reports Server (NTRS)

    1991-01-01

    The general theme for the workshop revolved around global environmental change. Over 170 individuals participated in the presentations and ensuing discussions about the many agency activities using airborne platforms and sensors in support of the U.S. Global Change Research Program (GCRP). The U.S. GCRP was developed as a central component of the U.S. Government's approach to global change and its contribution to worldwide efforts. An all-encompassing U.S. plan was developed by the Committee on Earth and Environmental Sciences (CEES), which continues as the interagency coordinating group for the program. The U.S. GCRP was established as a Presidential initiative in the FY90 budget, making it a particularly relevant topic for the workshop. The following are presented in the appendices: (1) final agenda and list of registrants; (2) final list of poster presenters; (3) steering group luncheon participants; (4) the draft resolution; and (5) selected handouts.

  15. Microneedle-assisted microparticle delivery by gene guns: experiments and modeling on the effects of particle characteristics.

    PubMed

    Zhang, Dongwei; Rielly, Chris D; Das, Diganta B

    2015-05-01

    Microneedles (MNs) have been shown to enhance the penetration depths of microparticles delivered by gene gun. This study aims to investigate the penetration of model microparticle materials, namely, tungsten (<1 μm diameter) and stainless steel (18 and 30 μm diameters) into a skin mimicking agarose gel to determine the effects of particle characteristics (mainly particle size). A number of experiments have been processed to analyze the passage percentage and the penetration depth of these microparticles in relation to the operating pressures and MN lengths. A comparison between the stainless steel and tungsten microparticles has been discussed, e.g. passage percentage, penetration depth. The passage percentage of tungsten microparticles is found to be less than the stainless steel. It is worth mentioning that the tungsten microparticles present unfavourable results which show that they cannot penetrate into the skin mimicking agarose gel without the help of MN due to insufficient momentum due to the smaller particle size. This condition does not occur for stainless steel microparticles. In order to further understand the penetration of the microparticles, a mathematical model has been built based on the experimental set up. The penetration depth of the microparticles is analyzed in relation to the size, operating pressure and MN length for conditions that cannot be obtained in the experiments. In addition, the penetration depth difference between stainless steel and tungsten microparticles is studied using the developed model to further understand the effect of an increased particle density and size on the penetration depth.

  16. Routing architecture and security for airborne networks

    NASA Astrophysics Data System (ADS)

    Deng, Hongmei; Xie, Peng; Li, Jason; Xu, Roger; Levy, Renato

    2009-05-01

    Airborne networks are envisioned to provide interconnectivity for terrestial and space networks by interconnecting highly mobile airborne platforms. A number of military applications are expected to be used by the operator, and all these applications require proper routing security support to establish correct route between communicating platforms in a timely manner. As airborne networks somewhat different from traditional wired and wireless networks (e.g., Internet, LAN, WLAN, MANET, etc), security aspects valid in these networks are not fully applicable to airborne networks. Designing an efficient security scheme to protect airborne networks is confronted with new requirements. In this paper, we first identify a candidate routing architecture, which works as an underlying structure for our proposed security scheme. And then we investigate the vulnerabilities and attack models against routing protocols in airborne networks. Based on these studies, we propose an integrated security solution to address routing security issues in airborne networks.

  17. Characterisation of particulate matter on airborne pollen grains.

    PubMed

    Ribeiro, Helena; Guimarães, Fernanda; Duque, Laura; Noronha, Fernando; Abreu, Ilda

    2015-11-01

    A characterization of the physical-chemical composition of the atmospheric PM adsorbed to airborne pollen was performed. Airborne pollen was sampled using a Hirst-type volumetric spore sampler and observed using a Field Emission Electron Probe Microanalyser for PM analysis. A secondary electron image was taken of each pollen grain and EDS spectra were obtained for individually adsorbed particles. All images were analysed and the size parameters of the particles adsorbed to pollen was determined. The measured particles' equivalent diameter varied between 0.1 and 25.8 μm, mostly in the fine fraction. The dominant particulates identified were Si-rich, Organic-rich, SO-rich, Metals & Oxides and Cl-rich. Significant daily differences were observed in the physical-chemical characteristics of particles adsorbed to the airborne pollen wall. These differences were correlated with weather parameters and atmospheric PM concentration. Airborne pollen has the ability to adsorb fine particles that may enhance its allergenicity.

  18. Airborne Hyperspectral Imaging of Seagrass and Coral Reef

    NASA Astrophysics Data System (ADS)

    Merrill, J.; Pan, Z.; Mewes, T.; Herwitz, S.

    2013-12-01

    This talk presents the process of project preparation, airborne data collection, data pre-processing and comparative analysis of a series of airborne hyperspectral projects focused on the mapping of seagrass and coral reef communities in the Florida Keys. As part of a series of large collaborative projects funded by the NASA ROSES program and the Florida Fish and Wildlife Conservation Commission and administered by the NASA UAV Collaborative, a series of airborne hyperspectral datasets were collected over six sites in the Florida Keys in May 2012, October 2012 and May 2013 by Galileo Group, Inc. using a manned Cessna 172 and NASA's SIERRA Unmanned Aerial Vehicle. Precise solar and tidal data were used to calculate airborne collection parameters and develop flight plans designed to optimize data quality. Two independent Visible and Near-Infrared (VNIR) hyperspectral imaging systems covering 400-100nm were used to collect imagery over six Areas of Interest (AOIs). Multiple collections were performed over all sites across strict solar windows in the mornings and afternoons. Independently developed pre-processing algorithms were employed to radiometrically correct, synchronize and georectify individual flight lines which were then combined into color balanced mosaics for each Area of Interest. The use of two different hyperspectral sensor as well as environmental variations between each collection allow for the comparative analysis of data quality as well as the iterative refinement of flight planning and collection parameters.

  19. Reduction in burst release of PLGA microparticles by incorporation into cubic phase-forming systems.

    PubMed

    Ahmed, Abid Riaz; Dashevsky, Andrei; Bodmeier, Roland

    2008-11-01

    A high initial burst release of an phosphorothioate oligonucleotide drug from poly(lactide-co-glycolide) (PLGA) microparticles prepared by the w/o/w solvent extraction/evaporation was reduced by incorporating the microparticles into the following glycerol monooleate (GMO) formulations: 1) pure molten GMO, 2) preformed cubic phase (GMO+water) or 3) low viscosity in situ cubic phase-forming formulations (GMO+water+cosolvent). The in situ cubic phase-forming formulations had a low viscosity in contrast to the first two formulations resulting in good dispersability of the microparticles and good syringability/injectability. Upon contact with an aqueous phase, a highly viscous cubic phase formed immediately entrapping the microparticles. A low initial burst and a continuous extended release over several weeks was obtained with all investigated formulations. The drug release profile could be well controlled by the cosolvent composition with the in situ systems.

  20. PUA/PSS multilayer coated CaCO3 microparticles as smart drug delivery vehicles.

    PubMed

    Du, Chao; Shi, Jun; Shi, Jin; Zhang, Li; Cao, Shaokui

    2013-10-01

    Hybrid CaCO3 microparticles coated by sodium poly(styrene sulfonate) (PSS) and aliphatic poly(urethane-amine) (PUA) were developed as thermal-/pH-responsive drug delivery vehicles via LbL self-assembly technique. The DOX release from the CaCO3 microparticles was higher than 60% within 36 h, whereas the value of PUA/PSS-coated microparticles was only 20%. The results demonstrated that the PUA/PSS multilayer coating could reduce the drug release rate and significantly assuage the initial burst release of DOX. In addition, the drug release of the hybrid microparticles was found to be thermal-/pH-dual responsive. More interestingly, more than 90% of DOX was released in 36 h at pH2.1 and 55 °C owing to the combined action of the dissolution of the CaCO3 core and the shrinkage of aliphatic PUA. PMID:23910272

  1. Analysis of synthetic and biological microparticles on several flow cytometric platforms***

    EPA Science Inventory

    Biological microparticles (MPs) are potentially important biomarkers for thrombosis, cancer, glomerulonephritis and other disease states. These MPs are generally accepted to be membrane vesicles extruded following cellular activation. While human blood cells range from 10-15 micr...

  2. PUA/PSS multilayer coated CaCO3 microparticles as smart drug delivery vehicles.

    PubMed

    Du, Chao; Shi, Jun; Shi, Jin; Zhang, Li; Cao, Shaokui

    2013-10-01

    Hybrid CaCO3 microparticles coated by sodium poly(styrene sulfonate) (PSS) and aliphatic poly(urethane-amine) (PUA) were developed as thermal-/pH-responsive drug delivery vehicles via LbL self-assembly technique. The DOX release from the CaCO3 microparticles was higher than 60% within 36 h, whereas the value of PUA/PSS-coated microparticles was only 20%. The results demonstrated that the PUA/PSS multilayer coating could reduce the drug release rate and significantly assuage the initial burst release of DOX. In addition, the drug release of the hybrid microparticles was found to be thermal-/pH-dual responsive. More interestingly, more than 90% of DOX was released in 36 h at pH2.1 and 55 °C owing to the combined action of the dissolution of the CaCO3 core and the shrinkage of aliphatic PUA.

  3. Surface modification of microparticles causes differential uptake responses in normal and tumoral human breast epithelial cells

    NASA Astrophysics Data System (ADS)

    Patiño, Tania; Soriano, Jorge; Barrios, Lleonard; Ibáñez, Elena; Nogués, Carme

    2015-06-01

    The use of micro- and nanodevices as multifunctional systems for biomedical applications has experienced an exponential growth during the past decades. Although a large number of studies have focused on the design and fabrication of new micro- and nanosystems capable of developing multiple functions, a deeper understanding of their interaction with cells is required. In the present study, we evaluated the effect of different microparticle surfaces on their interaction with normal and tumoral human breast epithelial cell lines. For this, AlexaFluor488 IgG functionalized polystyrene microparticles (3 μm) were coated with Polyethyleneimine (PEI) at two different molecular weights, 25 and 750 kDa. The effect of microparticle surface properties on cytotoxicity, cellular uptake and endocytic pathways were assessed for both normal and tumoral cell lines. Results showed a differential response between the two cell lines regarding uptake efficiency and mechanisms of endocytosis, highlighting the potential role of microparticle surface tunning for specific cell targeting.

  4. Electrocatalytic oxidation of methanol on polypyrrole film modified with platinum microparticles

    SciTech Connect

    Yang, H.; Lu, T.; Xue, K.; Sun, S.; Lu, G.; Chen, S.

    1997-07-01

    The electrocatalytic oxidation of methanol on polypyrrole (PPy) film modified with platinum microparticles has been studied by means of electrochemical and in situ Fourier transform infrared techniques. The Pt microparticles, which were incorporated in the PPy film by the technique of cyclic voltammetry, were uniformly dispersed. The modified electrode exhibits significant electrocatalytic activity for the oxidation of methanol. The catalytic activities were found to be dependent on Pt loading and the thickness of the PPy film. The linearly adsorbed CO species is the only intermediate of electrochemical oxidation of methanol and can be readily oxidized at the modified electrodes. The enhanced electrocatalytic activities may be due to the uniform dispersion of Pt microparticles in the PPy film and the synergistic effects of the highly dispersed Pt microparticles and the PPy film. Finally, a reaction mechanism is suggested.

  5. Biocatalytic self-assembly of nanostructured peptide microparticles using droplet microfluidics.

    PubMed

    Bai, Shuo; Debnath, Sisir; Gibson, Kirsty; Schlicht, Barbara; Bayne, Lauren; Zagnoni, Michele; Ulijn, Rein V

    2014-01-29

    Uniformly-sized, nanostructured peptide microparticles are generated by exploiting the ability of enzymes to serve (i) as catalysts, to control self-assembly within monodisperse, surfactant-stabilized water-in-oil microdroplets, and (ii) as destabilizers of emulsion interfaces, to enable facile transfer of the produced microparticles to water. This approach combines the advantages of biocatalytic self-assembly with the compartmentalization properties enabled by droplet microfluidics. Firstly, using microfluidic techniques, precursors of self-assembling peptide derivatives and enzymes are mixed in the microdroplets which upon catalytic conversion undergo molecular self-assembly into peptide particles, depending on the chemical nature of the precursors. Due to their amphiphilic nature, enzymes adsorb at the water-surfactant-oil interface of the droplets, inducing the transfer of peptide microparticles from the oil to the aqueous phase. Ultimately, through washing steps, enzymes can be removed from the microparticles which results in uniformely-sized particles composed of nanostructured aromatic peptide amphiphiles.

  6. Functionalised alginate flow seeding microparticles for use in Particle Image Velocimetry (PIV).

    PubMed

    Varela, Sylvana; Balagué, Isaac; Sancho, Irene; Ertürk, Nihal; Ferrando, Montserrat; Vernet, Anton

    2016-01-01

    Alginate microparticles as flow seeding fulfil all the requirements that are recommended for the velocity measurements in Particle Image Velocimetry (PIV). These spherical microparticles offer the advantage of being environmentally friendly, having excellent seeding properties and they can be produced via a very simple process. In the present study, the performances of alginate microparticles functionalised with a fluorescent dye, Rhodamine B (RhB), for PIV have been studied. The efficacy of fluorescence is appreciated in a number of PIV applications since it can boost the signal-to-noise ratio. Alginate microparticles functionalised with RhB have high emission efficiency, desirable match with fluid density and controlled size. The study of the particles behaviour in strong acid and basic solutions and ammonia is also included. This type of particles can be used for measurements with PIV and Planar Laser Induced Fluorescence (PLIF) simultaneously, including acid-base reactions. PMID:26878165

  7. Functionalised alginate flow seeding microparticles for use in Particle Image Velocimetry (PIV).

    PubMed

    Varela, Sylvana; Balagué, Isaac; Sancho, Irene; Ertürk, Nihal; Ferrando, Montserrat; Vernet, Anton

    2016-01-01

    Alginate microparticles as flow seeding fulfil all the requirements that are recommended for the velocity measurements in Particle Image Velocimetry (PIV). These spherical microparticles offer the advantage of being environmentally friendly, having excellent seeding properties and they can be produced via a very simple process. In the present study, the performances of alginate microparticles functionalised with a fluorescent dye, Rhodamine B (RhB), for PIV have been studied. The efficacy of fluorescence is appreciated in a number of PIV applications since it can boost the signal-to-noise ratio. Alginate microparticles functionalised with RhB have high emission efficiency, desirable match with fluid density and controlled size. The study of the particles behaviour in strong acid and basic solutions and ammonia is also included. This type of particles can be used for measurements with PIV and Planar Laser Induced Fluorescence (PLIF) simultaneously, including acid-base reactions.

  8. Exercise before and after SCUBA diving and the role of cellular microparticles in decompression stress.

    PubMed

    Madden, Dennis; Thom, Stephen R; Dujic, Zeljko

    2016-01-01

    Risk in SCUBA diving is often associated with the presence of gas bubbles in the venous circulation formed during decompression. Although it has been demonstrated time-after-time that, while venous gas emboli (VGE) often accompany decompression sickness (DCS), they are also frequently observed in high quantities in asymptomatic divers following even mild recreational dive profiles. Despite this VGE are commonly utilized as a quantifiable marker of the potential for an individual to develop DCS. Certain interventions such as exercise, antioxidant supplements, vibration, and hydration appear to impact VGE production and the decompression process. However promising these procedures may seem, the data are not yet conclusive enough to warrant changes in decompression procedure, possibly suggesting a component of individual response. We hypothesize that the impact of exercise varies widely in individuals and once tested, recommendations can be made that will reduce individual decompression stress and possibly the incidence of DCS. The understanding of physiological adaptations to diving stress can be applied in different diseases that include endothelial dysfunction and microparticle (MP) production. Exercise before diving is viewed by some as a protective form of preconditioning because some studies have shown that it reduces VGE quantity. We propose that MP production and clearance might be a part of this mechanism. Exercise after diving appears to impact the risk of adverse events as well. Research suggests that the arterialization of VGE presents a greater risk for DCS than when emboli are eliminated by the pulmonary circuit before they have a chance to crossover. Laboratory studies have demonstrated that exercise increases the incidence of crossover likely through extra-cardiac mechanisms such as intrapulmonary arterial-venous anastomoses (IPAVAs). This effect of exercise has been repeated in the field with divers demonstrating a direct relationship between exercise

  9. Exercise before and after SCUBA diving and the role of cellular microparticles in decompression stress.

    PubMed

    Madden, Dennis; Thom, Stephen R; Dujic, Zeljko

    2016-01-01

    Risk in SCUBA diving is often associated with the presence of gas bubbles in the venous circulation formed during decompression. Although it has been demonstrated time-after-time that, while venous gas emboli (VGE) often accompany decompression sickness (DCS), they are also frequently observed in high quantities in asymptomatic divers following even mild recreational dive profiles. Despite this VGE are commonly utilized as a quantifiable marker of the potential for an individual to develop DCS. Certain interventions such as exercise, antioxidant supplements, vibration, and hydration appear to impact VGE production and the decompression process. However promising these procedures may seem, the data are not yet conclusive enough to warrant changes in decompression procedure, possibly suggesting a component of individual response. We hypothesize that the impact of exercise varies widely in individuals and once tested, recommendations can be made that will reduce individual decompression stress and possibly the incidence of DCS. The understanding of physiological adaptations to diving stress can be applied in different diseases that include endothelial dysfunction and microparticle (MP) production. Exercise before diving is viewed by some as a protective form of preconditioning because some studies have shown that it reduces VGE quantity. We propose that MP production and clearance might be a part of this mechanism. Exercise after diving appears to impact the risk of adverse events as well. Research suggests that the arterialization of VGE presents a greater risk for DCS than when emboli are eliminated by the pulmonary circuit before they have a chance to crossover. Laboratory studies have demonstrated that exercise increases the incidence of crossover likely through extra-cardiac mechanisms such as intrapulmonary arterial-venous anastomoses (IPAVAs). This effect of exercise has been repeated in the field with divers demonstrating a direct relationship between exercise

  10. Double aperture focusing transducer for controlling microparticle motions in trapezoidal microchannels with surface acoustic waves

    NASA Astrophysics Data System (ADS)

    Tan, Ming K.; Tjeung, Ricky; Ervin, Hannah; Yeo, Leslie Y.; Friend, James

    2009-09-01

    We present a method for controlling the motion of microparticles suspended in an aqueous solution, which fills in a microchannel fabricated into a piezoelectric substrate, using propagating surface acoustic waves. The cross-sectional shape of this microchannel is trapezoidal, preventing the formation of acoustic standing waves across the channel width and therefore allowing the steering of microparticles. The induced acoustic streaming transports these particles to eliminate the use of external pumps for fluid actuation.

  11. Note: Detection of a single cobalt microparticle with a microfabricated atomic magnetometer

    NASA Astrophysics Data System (ADS)

    Maser, D.; Pandey, S.; Ring, H.; Ledbetter, M. P.; Knappe, S.; Kitching, J.; Budker, D.

    2011-08-01

    We present magnetic detection of a single, 2 μ m diameter cobalt microparticle using an atomic magnetometer based on a microfabricated vapor cell. These results represent an improvement by a factor of 105 in terms of the detected magnetic moment over previous work using atomic magnetometers to detect magnetic microparticles. The improved sensitivity is due largely to the use of small vapor cells. In an optimized setup, we predict detection limits of 0.17 μ m^3.

  12. Production of microparticles of molinate degrading biocatalysts using the spray drying technique.

    PubMed

    Lopes, Ana R; Sousa, Vera M; Estevinho, Berta N; Leite, José P; Moreira, Nuno F F; Gales, Luís; Rocha, Fernando; Nunes, Olga C

    2016-10-01

    Previous studies demonstrated the capability of mixed culture DC1 to mineralize the thiocarbamate herbicide molinate through the activity of molinate hydrolase (MolA). Because liquid suspensions are not compatible with long-term storage and are not easy to handle when bioremediation strategies are envisaged, in this study spray drying was evaluated as a cost-effective method to store and transport these molinate biocatalysts. Microparticles of mixed culture DC1 (DC1) and of cell free crude extracts containing MolA (MA) were obtained without any carrier polymer, and with calcium alginate (CA) or modified chitosan (MCt) as immobilizing agents. All the DC1 microparticles showed high molinate degrading activity upon storage for 6 months, or after 9 additions of ∼0.4 mM molinate over 1 month. The DC1-MCt microparticles were those with the highest survival rate and lowest heterogeneity. For MA microparticles, only MA-MCt degraded molinate. However, its Vmax was only 1.4% of that of the fresh cell free extract (non spray dried). The feasibility of using the DC1-MCt and MA-MCt microparticles in bioaugmentation processes was assessed in river water microcosms, using mass (g):volume (L) ratios of 1:13 and 1:0.25, respectively. Both type of microparticles removed ∼65-75% of the initial 1.5 mg L(-1) molinate, after 7 days of incubation. However, only DC1-MCt microparticles were able to degrade this environmental concentration of molinate without disturbing the native bacterial community. These results suggest that spray drying can be successfully used to produce DC1-MCt microparticles to remediate molinate polluted sites through a bioaugmentation strategy.

  13. Leukocyte mimetic polysaccharide microparticles tracked in vivo on activated endothelium and in abdominal aortic aneurysm.

    PubMed

    Bonnard, Thomas; Serfaty, Jean-Michel; Journé, Clément; Ho Tin Noe, Benoît; Arnaud, Denis; Louedec, Liliane; Derkaoui, Sidi Mohammed; Letourneur, Didier; Chauvierre, Cédric; Le Visage, Catherine

    2014-08-01

    We have developed injectable microparticles functionalized with fucoidan, in which sulfated groups mimic the anchor sites of P-selectin glycoprotein ligand-1 (PSGL-1), one of the principal receptors supporting leukocyte adhesion. These targeted microparticles were combined with a fluorescent dye and a T2(∗) magnetic resonance imaging (MRI) contrast agent, and then tracked in vivo with small animal imaging methods. Microparticles of 2.5μm were obtained by a water-in-oil emulsification combined with a cross-linking process of polysaccharide dextran, fluorescein isothiocyanate dextran, pullulan and fucoidan mixed with ultrasmall superparamagnetic particles of iron oxide. Fluorescent intravital microscopy observation revealed dynamic adsorption and a leukocyte-like behaviour of fucoidan-functionalized microparticles on a calcium ionophore induced an activated endothelial layer of a mouse mesentery vessel. We observed 20times more adherent microparticles on the activated endothelium area after the injection of functionalized microparticles compared to non-functionalized microparticles (197±11 vs. 10±2). This imaging tool was then applied to rats presenting an elastase perfusion model of abdominal aortic aneurysm (AAA) and 7.4T in vivo MRI was performed. Visual analysis of T2(∗)-weighted MR images showed a significant contrast enhancement on the inner wall of the aneurysm from 30min to 2h after the injection. Histological analysis of AAA cryosections revealed microparticles localized inside the aneurysm wall, in the same areas in which immunostaining shows P-selectin expression. The developed leukocyte mimetic imaging tool could therefore be relevant for molecular imaging of vascular diseases and for monitoring biologically active areas prone to rupture in AAA. PMID:24769117

  14. Abdominal Aortic Aneurysms Targeted by Functionalized Polysaccharide Microparticles: a new Tool for SPECT Imaging

    PubMed Central

    Bonnard, Thomas; Yang, Gonord; Petiet, Anne; Ollivier, Véronique; Haddad, Oualid; Arnaud, Denis; Louedec, Liliane; Bachelet-Violette, Laure; Derkaoui, Sidi Mohammed; Letourneur, Didier; Chauvierre, Cedric; Le Visage, Catherine

    2014-01-01

    Aneurysm diagnostic is nowadays limited by the lack of technology that enables early detection and rupture risk prediction. New non invasive tools for molecular imaging are still required. In the present study, we present an innovative SPECT diagnostic tool for abdominal aortic aneurysm (AAA) produced from injectable polysaccharide microparticles radiolabeled with technetium 99m (99mTc) and functionalized with fucoidan, a sulfated polysaccharide with the ability to target P-Selectin. P-Selectin is a cell adhesion molecule expressed on activated endothelial cells and platelets which can be found in the thrombus of aneurysms, as well as in other vascular pathologies. Microparticles with a maximum hydrodynamic diameter of 4 µm were obtained by crosslinking the polysaccharides dextran and pullulan. They were functionalized with fucoidan. In vitro interactions with human activated platelets were assessed by flow cytometry that demonstrated a specific affinity of fucoidan functionalized microparticles for P-Selectin expressed by activated platelets. For in vivo AAA imaging, microparticles were radiolabeled with 99mTc and intravenously injected into healthy and AAA rats obtained by elastase perfusion through the aorta wall. Animals were scanned by SPECT imaging. A strong contrast enhancement located in the abdominal aorta of AAA rats was obtained, while no signal was obtained in healthy rats or in AAA rats after injection of non-functionalized control microparticles. Histological studies revealed that functionalized radiolabeled polysaccharide microparticles were localized in the AAA wall, in the same location where P-Selectin was expressed. These microparticles therefore constitute a promising SPECT imaging tool for AAA and potentially for other vascular diseases characterized by P-Selectin expression. Future work will focus on validating the efficiency of the microparticles to diagnose these other pathologies and the different stages of AAA. Incorporation of a

  15. Microparticle based morphology engineering of filamentous microorganisms for industrial bio-production.

    PubMed

    Walisko, Robert; Krull, Rainer; Schrader, Jens; Wittmann, Christoph

    2012-11-01

    Filamentous microorganisms are important work horses in industrial biotechnology and supply enzymes, antibiotics, pharmaceuticals, bulk and fine chemicals. Here we highlight recent findings on the use of microparticles in the cultivation of filamentous bacteria and fungi, with the aim of enabling a more precise control of their morphology towards better production performance. First examples reveal a broad application range of microparticle based processes, since multiple filamentous organisms are controllable in their growth characteristics and respond by enhanced product formation.

  16. Development of β-cyclodextrin-based sustained release microparticles for oral insulin delivery.

    PubMed

    D'Souza, Bernadette; Bhowmik, Tuhin; Uddin, Mohammad Nasir; Oettinger, Carl; D'Souza, Martin

    2015-01-01

    Polymeric microparticles have been previously demonstrated to deliver various therapeutic agents efficiently to targeted regions by protecting the drug from harsh gastric milieu of the gastrointestinal tract. In this study, we investigated the hypoglycemic effect of β-cyclodextrin polymeric insulin microparticles in diabetic rats via the oral route of administration. β-cyclodextrin microparticles were prepared by a unique one-step spray-drying technique and stabilized by incorporating enteric retardant polymers in the formulation. The insulin-loaded microparticles had a mean size of 0.8 ± 0.25 μm with a zeta potential of 3.57 + 0.62 mV. As seen with the chromatographic analysis, the drug content in the microparticles was determined to be 94.9 ± 2.77%. RAW macrophage cells showed greater than 80% viability after 24 h of incubation with the insulin and blank microparticles. For the in vitro release study, the microparticles were able to protect the insulin in gastric fluid where no significant release was detected, followed by only 50% release in intestinal fluid for the first 8 h of the study. This was seen to correlate with the in vivo data where 50% glucose inhibition was seen after 8 h of oral administration in diabetic rats. This data suggest that the oral insulin microparticles were able to reduce glucose levels in disease conditions and would be a favorable route of administration to patients as an alternative to daily subcutaneous injections.

  17. Placental Microparticles and MicroRNAs in Pregnant Women with Plasmodium falciparum or HIV Infection

    PubMed Central

    Moro, Laura; Bardají, Azucena; Macete, Eusebio; Barrios, Diana; Morales-Prieto, Diana M.; España, Carolina; Mandomando, Inacio; Sigaúque, Betuel; Dobaño, Carlota; Markert, Udo R.; Benitez-Ribas, Daniel; Alonso, Pedro L.; Menéndez, Clara; Mayor, Alfredo

    2016-01-01

    Background During pregnancy, syncytiotrophoblast vesicles contribute to maternal tolerance towards the fetus, but also to pathologies such as pre-eclampsia. The aim of the study was to address whether Plasmodium falciparum and HIV infections in pregnancy affect the secretion, microRNA content and function of trophoblast microparticles. Methods Microparticles were isolated and characterized from 122 peripheral plasmas of Mozambican pregnant women, malaria- and/or HIV-infected and non-infected. Expression of placenta-related microRNAs in microparticles was analysed by qPCR and the effect of circulating microparticles on dendritic cells assessed by phenotype analysis and cytokine/chemokine measurement. Results Concentrations of total and trophoblast microparticles detected by flow cytometry were higher in HIV-positive (P = 0.005 and P = 0.030, respectively) compared to non-infected mothers, as well as in women delivering low birthweight newborns (P = 0.032 and P = 0.021, respectively). miR-517c was overexpressed in mothers with placental malaria (P = 0.034), compared to non-infected. Microparticles from HIV-positive induced a higher expression of MHCII (P = 0.021) and lower production of MCP1 (P = 0.008) than microparticles from non-infected women. Conclusions In summary, alterations in total and trophoblast microparticles associated with malaria and HIV in pregnant women may have an immunopathogenic role. The potential for placental-derived vesicles and microRNAs as biomarkers of adverse outcomes during pregnancy and malaria infection should be confirmed in future studies. PMID:26757431

  18. Capreomycin oleate microparticles for intramuscular administration: Preparation, in vitro release and preliminary in vivo evaluation.

    PubMed

    Cambronero-Rojas, Adrián; Torres-Vergara, Pablo; Godoy, Ricardo; von Plessing, Carlos; Sepúlveda, Jacqueline; Gómez-Gaete, Carolina

    2015-07-10

    Capreomycin sulfate (CS) is a second-line drug used for the treatment of multidrug-resistant tuberculosis (MDR-TB). The adverse effects profile and uncomfortable administration scheme of CS has led to the development of formulations based on liposomes and polymeric microparticles. However, as CS is a water-soluble peptide that does not encapsulate properly into hydrophobic particulate matrices, it was necessary to reduce its aqueous solubility by forming the pharmacologically active capreomycin oleate (CO) ion pair. The aim of this research was to develop a new formulation of CO for intramuscular injection, based on biodegradable microparticles that encapsulate CO in order to provide a controlled release of the drug with reduced local and systemic adverse effects. The CO-loaded microparticles prepared by spray drying or solvent emulsion-evaporation were characterized in their morphology, encapsulation efficiency, in vitro/in vivo kinetics and tissue tolerance. Through scanning electron microscopy it was confirmed that the microparticles were monodisperse and spherical, with an optimal size for intramuscular administration. The interaction between CO and the components of the microparticle matrix was confirmed on both formulations by X-ray powder diffraction and differential scanning calorimetry analyses. The encapsulation efficiencies for the spray-dried and emulsion-evaporation microparticles were 92% and 56%, respectively. The in vitro kinetics performed on both formulations demonstrated a controlled and continuous release of CO from the microparticles, which was successfully reproduced on an in vivo rodent model. The results of the histological analysis demonstrated that none of the formulations produced significant tissue damage on the site of injection. Therefore, the results suggest that injectable CO microparticles obtained by spray drying and solvent emulsion-evaporation could represent an interesting therapeutic alternative for the treatment of MDR

  19. Microparticles with bimodal nanoporosity derived by microemulsion templating.

    PubMed

    Carroll, Nick J; Pylypenko, Svitlana; Atanassov, Plamen B; Petsev, Dimiter N

    2009-12-01

    Oil, water, and surfactant liquid mixtures exhibit very complex phase behavior. Depending on the conditions, such mixtures give rise to highly organized structures. A proper selection of the type and concentration of surfactants determines the structuring at the nanoscale level. In this Article, we show that hierarchically bimodal porous structures can be obtained by templating silica microparticles with a specially designed surfactant micelle/microemulsion mixture. Tuning the phase state by adjusting the surfactant composition and concentration allows for the controlled design of a system where microemulsion droplets coexist with smaller surfactant micellar structures. The microemulsion droplet and micellar dimensions determine the two types of pore sizes. We also demonstrate the fabrication of carbon and carbon/platinum replicas of the silica microspheres using a "lost-wax" approach. Such particles have great potential for the design of electrocatalysts for fuel cells, chromatography separations, and other applications. PMID:19928946

  20. Formulation of wax oxybenzone microparticles using a factorial approach.

    PubMed

    Gomaa, Y A; Darwish, I A; Boraei, N A; El-Khordagui, L K

    2010-01-01

    Oxybenzone wax microparticles (MPs) were prepared by the hydrophobic congealable disperse phase method. The formulation of oxybenzone-loaded MPs was optimized using a 2⁴ experimental design. Factorial analysis indicated that the main MP characteristics were influenced by initial drug loading, emulsification speed, emulsifier concentration and hydrophilic-lipophilic balance. MPs were spherical with 50.5–88.1 μm size range, 17.8–38.9 drug content in mg/100 mg MPs and 33.1–87.2% oxybenzone release in 1 h. A wide range of sunscreen delivery systems suitable for different formulation purposes were generated which may contribute to the advanced formulation of sunscreen products with improved performance. PMID:20681744

  1. Formulation of wax oxybenzone microparticles using a factorial approach.

    PubMed

    Gomaa, Y A; Darwish, I A; Boraei, N A; El-Khordagui, L K

    2010-01-01

    Oxybenzone wax microparticles (MPs) were prepared by the hydrophobic congealable disperse phase method. The formulation of oxybenzone-loaded MPs was optimized using a 2⁴ experimental design. Factorial analysis indicated that the main MP characteristics were influenced by initial drug loading, emulsification speed, emulsifier concentration and hydrophilic-lipophilic balance. MPs were spherical with 50.5–88.1 μm size range, 17.8–38.9 drug content in mg/100 mg MPs and 33.1–87.2% oxybenzone release in 1 h. A wide range of sunscreen delivery systems suitable for different formulation purposes were generated which may contribute to the advanced formulation of sunscreen products with improved performance.

  2. Microparticles with bimodal nanoporosity derived by microemulsion templating.

    PubMed

    Carroll, Nick J; Pylypenko, Svitlana; Atanassov, Plamen B; Petsev, Dimiter N

    2009-12-01

    Oil, water, and surfactant liquid mixtures exhibit very complex phase behavior. Depending on the conditions, such mixtures give rise to highly organized structures. A proper selection of the type and concentration of surfactants determines the structuring at the nanoscale level. In this Article, we show that hierarchically bimodal porous structures can be obtained by templating silica microparticles with a specially designed surfactant micelle/microemulsion mixture. Tuning the phase state by adjusting the surfactant composition and concentration allows for the controlled design of a system where microemulsion droplets coexist with smaller surfactant micellar structures. The microemulsion droplet and micellar dimensions determine the two types of pore sizes. We also demonstrate the fabrication of carbon and carbon/platinum replicas of the silica microspheres using a "lost-wax" approach. Such particles have great potential for the design of electrocatalysts for fuel cells, chromatography separations, and other applications.

  3. Magnetophoresis of diamagnetic microparticles in a weak magnetic field.

    PubMed

    Zhu, Gui-Ping; Hejiazan, Majid; Huang, Xiaoyang; Nguyen, Nam-Trung

    2014-12-21

    Magnetic manipulation is a promising technique for lab-on-a-chip platforms. The magnetic approach can avoid problems associated with heat, surface charge, ionic concentration and pH level. The present paper investigates the migration of diamagnetic particles in a ferrofluid core stream that is sandwiched between two diamagnetic streams in a uniform magnetic field. The three-layer flow is expanded in a circular chamber for characterisation based on imaging of magnetic nanoparticles and fluorescent microparticles. A custom-made electromagnet generates a uniform magnetic field across the chamber. In a relatively weak uniform magnetic field, the diamagnetic particles in the ferrofluid move and spread across the chamber. Due to the magnetization gradient formed by the ferrofluid, diamagnetic particles undergo negative magnetophoresis and move towards the diamagnetic streams. The effects of magnetic field strength and the concentration of diamagnetic particles are studied in detail. PMID:25325774

  4. Micro-Particles As Thermal Probes In Plasmas

    SciTech Connect

    Maurer, H.; Basner, R.; Kersten, H.

    2008-09-07

    Temperature sensitive 'thermographic' phosphors are utilized for measuring the temperature of micro-particles levitated in a plasma.The equilibrium temperature of particles T{sub p} in a plasma is determined by the sum of the energy fluxes between their surface and the surrounding plasma. By variation of gas composition and plasma parameters the different contributions to the total energy flux can be influenced. By measurement of the temperature of the microscopic probe particles, valuable information about the physics of plasma-particle interaction can be obtained. This is particularly of interest for dusty plasma research and the improvement of technical plasmas.Preliminary measurements of T{sub p} in the plasma-reactor PULVA-INP are presented, which show quite promising results.

  5. Coaxial electrospray of microparticles and nanoparticles for biomedical applications

    PubMed Central

    Zhang, Leilei; Huang, Jiwei; Si, Ting; Xu, Ronald X

    2013-01-01

    Coaxial electrospray is an electrohydrodynamic process that produces multilayer microparticles and nanoparticles by introducing coaxial electrified jets. In comparison with other microencapsulation/nanoencapsulation processes, coaxial electrospray has several potential advantages such as high encapsulation efficiency, effective protection of bioactivity and uniform size distribution. However, process control in coaxial electrospray is challenged by the multiphysical nature of the process and the complex interplay of multiple design, process and material parameters. This paper reviews the previous works and the recent advances in design, modeling and control of a coaxial electrospray process. The review intends to provide general guidance for coaxial electrospray and stimulate further research and development interests in this promising microencapsulation/nanoencapsulation process. PMID:23249155

  6. Nano and microparticles emission during laser cleaning of stone

    NASA Astrophysics Data System (ADS)

    Ostrowski, Roman; Marczak, Jan; Strzelec, Marek; Barcikowski, Stephan

    2007-02-01

    Air contaminants which emerge during laser ablation often cause health risks if released in the workplace and decrease laser cleaning efficiency if redeposited at the material surface. In addition, ultra-fine particles are generated if short laser pulses are applied. Consequently, a description of the nano and microparticle aerosol generation and the influence of the laser parameters, such as fluence and pulse energy, and type of material surface on the particle size distribution is given in the presented paper. The conducted experiments have shown that for applied laser fluences almost 80% of all emitted particles are in the nanoparticle size range of 30 - 100 nm. The high respirability of such particles can pose health risks, so suitable capture systems near to the processing zone or personal protective equipment such as respiratory masks are required.

  7. Dynamics of microparticles trapped in a perfect vortex beam.

    PubMed

    Chen, Mingzhou; Mazilu, Michael; Arita, Yoshihiko; Wright, Ewan M; Dholakia, Kishan

    2013-11-15

    We analyze microparticle dynamics within a "perfect" vortex beam. In contrast to other vortex fields, for any given integer value of the topological charge, a "perfect" vortex beam has the same annular intensity profile with fixed radius of peak intensity. For a given topological charge, the field possesses a well-defined orbital angular momentum density at each point in space, invariant with respect to azimuthal position. We experimentally create a perfect vortex and correct the field in situ, to trap and set in motion trapped microscopic particles. For a given topological charge, a single trapped particle exhibits the same local angular velocity moving in such a field independent of its azimuthal position. We also investigate particle dynamics in "perfect" vortex beams of fractional topological charge. This light field may be applied for novel studies in optical trapping of particles, atoms, and quantum gases.

  8. Coaxial electrohydrodynamic atomization: microparticles for drug delivery applications.

    PubMed

    Davoodi, Pooya; Feng, Fang; Xu, Qingxing; Yan, Wei-Cheng; Tong, Yen Wah; Srinivasan, M P; Sharma, Vijay Kumar; Wang, Chi-Hwa

    2015-05-10

    As cancer takes its toll on human health and well-being, standard treatment techniques such as chemotherapy and radiotherapy often fall short of ideal solutions. In particular, adverse side effects due to excess dosage and collateral damage to healthy cells as well as poor patient compliance due to multiple administrations continue to pose challenges in cancer treatment. Thus, the development of appropriately engineered drug delivery systems (DDS) for effective, controlled and sustained delivery of drugs is of interest for patient treatment. Moreover, the physiopathological characteristics of tumors play an essential role in the success of cancer treatment. Here, we present an overview of the application of double-walled microparticles for local drug delivery with particular focus on the electrohydrodynamic atomization (EHDA) technique and its fabrication challenges. The review highlights the importance of a combination of experimental data and computational simulations for the design of an optimal delivery system. PMID:25483422

  9. Dynamics of charged microparticles at oil-water interfaces.

    PubMed

    Wu, Chih-Yuan; Tarimala, Sowmitri; Dai, Lenore L

    2006-02-28

    Solid-stabilized emulsions have been used as a model system to investigate the dynamics of charged microparticles with diameters of 1.1 microm at oil-water interfaces. Using confocal microscopy, we investigated the influences of interfacial curvature, cluster size, and temperature on the diffusion of solid particles. Our work suggests that a highly curved emulsion interface slows the motion of solid particles. This qualitatively supports the theoretical work by Danov et al. (Danov, K. D.; Dimova, R.; Pouligny, B. Phys. Fluids 2000, 12, 2711); however, the interfacial curvature effect decreases with increasing oil-phase viscosity. The diffusion of multiparticle clusters at oil-water interfaces is a strong function of cluster size and oil-phase viscosity and can be quantitatively related to fractal dimension. Finally, we report the influence of temperature and quantify the diffusion activation energy and friction factor of the particles at the investigated oil-water interfaces.

  10. Carbon monoxide inhalation increases microparticles causing vascular and CNS dysfunction

    SciTech Connect

    Xu, Jiajun; Yang, Ming; Kosterin, Paul; Salzberg, Brian M.; Milovanova, Tatyana N.; Bhopale, Veena M.; Thom, Stephen R.

    2013-12-01

    We hypothesized that circulating microparticles (MPs) play a role in pro-inflammatory effects associated with carbon monoxide (CO) inhalation. Mice exposed for 1 h to 100 ppm CO or more exhibit increases in circulating MPs derived from a variety of vascular cells as well as neutrophil activation. Tissue injury was quantified as 2000 kDa dextran leakage from vessels and as neutrophil sequestration in the brain and skeletal muscle; and central nervous system nerve dysfunction was documented as broadening of the neurohypophysial action potential (AP). Indices of injury occurred following exposures to 1000 ppm for 1 h or to 1000 ppm for 40 min followed by 3000 ppm for 20 min. MPs were implicated in causing injuries because infusing the surfactant MP lytic agent, polyethylene glycol telomere B (PEGtB) abrogated elevations in MPs, vascular leak, neutrophil sequestration and AP prolongation. These manifestations of tissue injury also did not occur in mice lacking myeloperoxidase. Vascular leakage and AP prolongation were produced in naïve mice infused with MPs that had been obtained from CO poisoned mice, but this did not occur with MPs obtained from control mice. We conclude that CO poisoning triggers elevations of MPs that activate neutrophils which subsequently cause tissue injuries. - Highlights: • Circulating microparticles (MPs) increase in mice exposed to 100 ppm CO or more. • MPs are lysed by infusing the surfactant polyethylene glycol telomere B. • CO-induced MPs cause neutrophil activation, vascular leak and CNS dysfunction. • Similar tissue injuries do not arise with MPs obtained from air-exposed, control mice.

  11. Aluminum silicide microparticles transformed from aluminum thin films by hypoeutectic interdiffusion

    PubMed Central

    2014-01-01

    Aluminum silicide microparticles with oxidized rough surfaces were formed on Si substrates through a spontaneous granulation process of Al films. This microparticle formation was caused by interdiffusion of Al and Si atoms at hypoeutectic temperatures of Al-Si systems, which was driven by compressive stress stored in Al films. The size, density, and the composition of the microparticles could be controlled by adjusting the annealing temperature, time, and the film thickness. High-density microparticles of a size around 10 μm and with an atomic ratio of Si/Al of approximately 0.8 were obtained when a 90-nm-thick Al film on Si substrate was annealed for 9 h at 550°C. The microparticle formation resulted in a rapid increase of the sheet resistance, which is a consequence of substantial consumption of Al film. This simple route to size- and composition-controllable microparticle formation may lay a foundation stone for the thermoelectric study on Al-Si alloy-based heterogeneous systems. PMID:24994964

  12. Mechanism of platelet adhesion to von Willebrand factor and microparticle formation under high shear stress

    PubMed Central

    Reininger, Armin J.; Heijnen, Harry F. G.; Schumann, Hannah; Specht, Hanno M.; Schramm, Wolfgang; Ruggeri, Zaverio M.

    2006-01-01

    We describe here the mechanism of platelet adhesion to immobilized von Willebrand factor (VWF) and subsequent formation of platelet-derived microparticles mediated by glycoprotein Ibα (GPIbα) under high shear stress. As visualized in whole blood perfused in a flow chamber, platelet attachment to VWF involved one or few membrane areas of 0.05 to 0.1 μm2 that formed discrete adhesion points (DAPs) capable of resisting force in excess of 160 pN. Under the influence of hydrodynamic drag, membrane tethers developed between the moving platelet body and DAPs firmly adherent to immobilized VWF. Continued stretching eventually caused the separation of many such tethers, leaving on the surface tube-shaped or spherical microparticles with a diameter as low as 50 to 100 nm. Adhesion receptors (GPIbα, αIIbβ3) and phosphatidylserine were expressed on the surface of these microparticles, which were procoagulant. Shearing platelet-rich plasma at the rate of 10 000 s–1 in a cone-and-plate viscosimeter increased microparticle counts up to 55-fold above baseline. Blocking the GPIb-VWF interaction abolished microparticle generation in both experimental conditions. Thus, a biomechanical process mediated by GPIbα-VWF bonds in rapidly flowing blood may not only initiate platelet arrest onto reactive vascular surfaces but also generate procoagulant microparticles that further enhance thrombus formation. PMID:16449527

  13. Development of biodegradable methylprednisolone microparticles for treatment of articular pathology using a spray-drying technique

    PubMed Central

    Tobar-Grande, Blanca; Godoy, Ricardo; Bustos, Paulina; von Plessing, Carlos; Fattal, Elias; Tsapis, Nicolas; Olave, Claudia; Gómez-Gaete, Carolina

    2013-01-01

    In this work, microparticles were prepared by spray-drying using albumin, chondroitin sulfate, and hyaluronic acid as excipients to create a controlled-release methylprednisolone system for use in inflammatory disorders such as arthritis. Scanning electron microscopy demonstrated that these microparticles were almost spherical, with development of surface wrinkling as the methylprednisolone load in the formulation was increased. The methylprednisolone load also had a direct influence on the mean diameter and zeta potential of the microparticles. Interactions between formulation excipients and the active drug were evaluated by x-ray diffraction, differential scanning calorimetry, and thermal gravimetric analysis, showing limited amounts of methylprednisolone in a crystalline state in the loaded microparticles. The encapsulation efficiency of methylprednisolone was approximately 89% in all formulations. The rate of methylprednisolone release from the microparticles depended on the initial drug load in the formulation. In vitro cytotoxic evaluation using THP-1 cells showed that none of the formulations prepared triggered an inflammatory response on release of interleukin-1β, nor did they affect cellular viability, except for the 9.1% methylprednisolone formulation, which was the maximum test concentration used. The microparticles developed in this study have characteristics amenable to a therapeutic role in inflammatory pathology, such as arthritis. PMID:23737670

  14. Continuous supercritical emulsions extraction: a new technology for biopolymer microparticles production.

    PubMed

    Porta, G Della; Falco, N; Reverchon, E

    2011-03-01

    Supercritical emulsion extraction (SEE) was recently proposed for the production of biopolymer microparticles starting from oil-in-water emulsions. This technology can improve the product quality because of the fast and selective extraction of the dispersed oily phase by using supercritical carbon dioxide (SC-CO(2) ). However, until now, SEE was proposed in batch configuration, sharing with the traditional processes an intrinsically discontinuous operation and problems of batches reproducibility and process yield. In this study, by using a countercurrent packed column, the SEE process was proposed in a continuous operating mode (SEE-CM) for the production of poly-lactic-co-glycolic acid (PLGA) microparticles. The new process design takes advantage of the large contact area between the SC-CO(2) and emulsion allowing the production of PLGA microparticles with controlled and narrow size distributions in only few minutes. SEE-CM operating parameters such as pressure, temperature, and flow rate ratios were analyzed and the process efficiency in terms of recovered material and its size distribution compared with SEE (batch mode operation) and conventional evaporation technology. PLGA microparticles showed a mean particle size between 1-3 µm (depending on the droplet sizes) with a SD that was always smaller than that associated with particles produced by discontinuous processes. Single and double emulsions were successfully treated and the microparticles physico-chemical properties showed no morphological and structural differences between the SEE-CM-produced microparticles and the ones obtained by conventional evaporation technology. PMID:20967801

  15. Furosemide Loaded Silica-Lipid Hybrid Microparticles: Formulation Development, in vitro and ex vivo Evaluation

    PubMed Central

    Sambaraj, Swapna; Ammula, Divya; Nagabandi, Vijaykumar

    2015-01-01

    Purpose: The main objective of the current research work was to formulate and evaluate furosemide loaded silica lipid hybrid microparticles for improved oral delivery. A novel silica-lipid hybrid microparticulate system is used for enhancing the oral absorption of low solubility and low permeability of (BCS Class IV) drugs. Silica-lipid hybrid microparticles include the drug solubilising effect of dispersed lipids and stabilizing effect of hydrophilic silica particles to increase drug solubilisation, which leads to enhanced oral bioavailability. Methods: The slica lipid hybrid (SLH) microparticles were composed of poorly soluble drug (furosemide), dispersion of oil phase (Soya bean oil and miglyol) in lecithin (Phospholipoid 90H), non-ionic surfactant (Polysorbate 80) and adsorbent (Aerosol 380). Saturation solubility studies were performed in different oils and surfactants with increased concentration of drug revealed increased solubility of furosemide. Results: In vitro dissolution studies conducted under simulated gastric medium revealed 2-4 fold increase in dissolution efficiencies for SLH microparticles compared to that of pure drug (furosemide) and marketed formulation Lasix®. Ex vivo studies showed enhanced lipid digestibility, which improved drug permeability. Solid-state characterization of SLH microparticles by X-ray powder diffraction and Fourier transform infrared spectroscopic analysis confirmed non-crystalline nature and more compatibility of furosemide in silica-lipid hybrid microparticles. Conclusion: It can be concluded that the role of lipids and hydrophilic silica based carrier highlighted in enhancing solubility and permeability, and hence the oral bioavailability of poorly soluble drugs. PMID:26504763

  16. Phagocytosis of PLGA Microparticles in Rat Peritoneal Exudate Cells: A Time-Dependent Study

    NASA Astrophysics Data System (ADS)

    Gomes, Anderson De Jesus; Nain Lunardi, Claure; Henrique Caetano, Flávio; Orive Lunardi, Laurelúcia; da Hora Machado, Antonio Eduardo

    2006-07-01

    With the purpose of enhancing the efficacy of microparticle-encapsulated therapeutic agents, in this study we evaluated the phagocytic ability of rat peritoneal exudate cells and the preferential location of poly(D,L-lactide-co-glycolic acid) (PLGA) microparticles inside these cells. The microparticles used were produced by a solvent evaporation method and were characterized by dynamic light scattering (DLS), transmission electron microscopy (TEM), and scanning electron microscopy (SEM). Size distribution analysis using DLS and SEM showed that the particles were spherical, with diameters falling between 0.5 and 1.5 [mu]m. Results from cell adhesion by SEM assay, indicated that the PLGA microparticles are not toxic to cells and do not cause any distinct damage to them as confirmed by the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide) assay. Among the large variety of cell populations found in the peritoneal exudates (neutrophils, eosinophils, monocytes, and macrophages), TEM showed that only the latter phagocytosed PLGA microparticles, in a time-dependent manner. The results obtained indicate that the microparticles studied show merits as possible carriers of drugs for intracellular delivery.

  17. Chitosan-modified porous silicon microparticles for enhanced permeability of insulin across intestinal cell monolayers.

    PubMed

    Shrestha, Neha; Shahbazi, Mohammad-Ali; Araújo, Francisca; Zhang, Hongbo; Mäkilä, Ermei M; Kauppila, Jussi; Sarmento, Bruno; Salonen, Jarno J; Hirvonen, Jouni T; Santos, Hélder A

    2014-08-01

    Porous silicon (PSi) based particulate systems are emerging as an important drug delivery system due to its advantageous properties such as biocompatibility, biodegradability and ability to tailor the particles' physicochemical properties. Here, annealed thermally hydrocarbonized PSi (AnnTHCPSi) and undecylenic acid modified AnnTHCPSi (AnnUnTHCPSi) microparticles were developed as a PSi-based platform for oral delivery of insulin. Chitosan (CS) was used to modify the AnnUnTHCPSi microparticles to enhance the intestinal permeation of insulin. Surface modification with CS led to significant increase in the interaction of PSi microparticles with Caco-2/HT-29 cell co-culture monolayers. Compared to pure insulin, the CS-conjugated microparticles significantly improved the permeation of insulin across the Caco-2/HT-29 cell monolayers, with ca. 20-fold increase in the amount of insulin permeated and ca. 7-fold increase in the apparent permeability (P(app)) value. Moreover, among all the investigated particles, the CS-conjugated microparticles also showed the highest amount of insulin associated with the mucus layer and the intestinal Caco-2 cells and mucus secreting HT-29 cells. Our results demonstrate that CS-conjugated AnnUnTHCPSi microparticles can efficiently enhance the insulin absorption across intestinal cells, and thus, they are promising microsystems for the oral delivery of proteins and peptides across the intestinal cell membrane.

  18. Starch, inulin and maltodextrin as encapsulating agents affect the quality and stability of jussara pulp microparticles.

    PubMed

    Lacerda, Ellen Cristina Quirino; Calado, Verônica Maria de Araújo; Monteiro, Mariana; Finotelli, Priscilla Vanessa; Torres, Alexandre Guedes; Perrone, Daniel

    2016-10-20

    The influence of encapsulating carbohydrates (EC) with varying properties on the technological and functional properties of jussara pulp microparticles produced by spray drying were evaluated using experimental design. Microparticles produced with sodium octenyl succinate (OSA) starch at 0.5 core to EC ratio and with mixtures of inulin and maltodextrin at 1.0 and 2.0 core to EC ratio showed darker color, and higher anthocyanins contents and antioxidant activity. Seven microparticles showing high water solubility and desirable surface morphology. Hygroscopicity (10.7% and 11.5%) and wettability (41s and 43s) were improved when OSA starch and mixtures of inulin and maltodextrin were used. The anthocyanins contents and color of the microparticles did not change when exposed to light at 50°C for 38days. Finally, microparticles produced at 1.0 core to EC ratio with 2/3 OSA starch, 1/6 inulin and 1/6 maltodextrin were selected. These microparticles may be applied as colorant in numerous foods, whilst adding prebiotic fiber and anthocyanins.

  19. Starch, inulin and maltodextrin as encapsulating agents affect the quality and stability of jussara pulp microparticles.

    PubMed

    Lacerda, Ellen Cristina Quirino; Calado, Verônica Maria de Araújo; Monteiro, Mariana; Finotelli, Priscilla Vanessa; Torres, Alexandre Guedes; Perrone, Daniel

    2016-10-20

    The influence of encapsulating carbohydrates (EC) with varying properties on the technological and functional properties of jussara pulp microparticles produced by spray drying were evaluated using experimental design. Microparticles produced with sodium octenyl succinate (OSA) starch at 0.5 core to EC ratio and with mixtures of inulin and maltodextrin at 1.0 and 2.0 core to EC ratio showed darker color, and higher anthocyanins contents and antioxidant activity. Seven microparticles showing high water solubility and desirable surface morphology. Hygroscopicity (10.7% and 11.5%) and wettability (41s and 43s) were improved when OSA starch and mixtures of inulin and maltodextrin were used. The anthocyanins contents and color of the microparticles did not change when exposed to light at 50°C for 38days. Finally, microparticles produced at 1.0 core to EC ratio with 2/3 OSA starch, 1/6 inulin and 1/6 maltodextrin were selected. These microparticles may be applied as colorant in numerous foods, whilst adding prebiotic fiber and anthocyanins. PMID:27474594

  20. Microparticles Produced by the Hydrogel Template Method for Sustained Drug Delivery

    PubMed Central

    Lu, Ying; Sturek, Michael; Park, Kinam

    2014-01-01

    Polymeric microparticles have been used widely for sustained drug delivery. Current methods of microparticle production can be improved by making homogeneous particles in size and shape, increasing the drug loading, and controlling the initial burst release. In the current study, the hydrogel template method was used to produce homogeneous poly(lactide-co-glycolide) (PLGA) microparticles and to examine formulation and process-related parameters. Poly(vinyl alcohol) (PVA) was used to make hydrogel templates. The parameters examined include PVA molecular weight, type of PLGA (as characterized by lactide content, inherent viscosity), polymer concentration, drug concentration and composition of solvent system. Three model compounds studied were risperidone, methylprednisolone acetate and paclitaxel. The ability of the hydrogel template method to produce microparticles with good conformity to template was dependent on molecular weight of PVA and viscosity of the PLGA solution. Drug loading and encapsulation efficiency were found to be influenced by PLGA lactide content, polymer concentration and composition of the solvent system. The drug loading and encapsulation efficiency were 28.7% and 82% for risperidone, 31.5% and 90% for methylprednisolone acetate, and 32.2 % and 92 % for paclitaxel, respectively. For all three drugs, release was sustained for weeks, and the in vitro release profile of risperidone was comparable to that of microparticles prepared using the conventional emulsion method. The hydrogel template method provides a new approach of manipulating microparticles. PMID:24333903

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

    PubMed

    Rondeau, Elisabeth; Cooper-White, Justin J

    2012-06-01

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

  2. Control of Alginate Core Size in Alginate-Poly (Lactic-Co-Glycolic) Acid Microparticles

    NASA Astrophysics Data System (ADS)

    Lio, Daniel; Yeo, David; Xu, Chenjie

    2016-01-01

    Core-shell alginate-poly (lactic-co-glycolic) acid (PLGA) microparticles are potential candidates to improve hydrophilic drug loading while facilitating controlled release. This report studies the influence of the alginate core size on the drug release profile of alginate-PLGA microparticles and its size. Microparticles are synthesized through double-emulsion fabrication via a concurrent ionotropic gelation and solvent extraction. The size of alginate core ranges from approximately 10, 50, to 100 μm when the emulsification method at the first step is homogenization, vortexing, or magnetic stirring, respectively. The second step emulsification for all three conditions is performed with magnetic stirring. Interestingly, although the alginate core has different sizes, alginate-PLGA microparticle diameter does not change. However, drug release profiles are dramatically different for microparticles comprising different-sized alginate cores. Specifically, taking calcein as a model drug, microparticles containing the smallest alginate core (10 μm) show the slowest release over a period of 26 days with burst release less than 1 %.

  3. Preparation and characterization of microparticles of piroxicam by spray drying and spray chilling methods

    PubMed Central

    Dixit, M.; Kini, A.G.; Kulkarni, P.K.

    2010-01-01

    Piroxicam, an anti-inflammatory drug, exhibits poor water solubility and flow properties, poor dissolution and poor wetting. Consequently, the aim of this study was to improve the dissolution of piroxicam. Microparticles containing piroxicam were produced by spray drying, using isopropyl alcohol and water in the ratio of 40:60 v/v as solvent system, and spray chilling technology by melting the drug and chilling it with a pneumatic nozzle to enhance dissolution rate. The prepared formulations were evaluated for in vitro dissolution and solubility. The prepared drug particles were characterized by scanning electron microscopy (SEM), differential scanning calorimeter, X-ray diffraction and Fourier transform infrared spectroscopy. Dissolution profile of the spray dried microparticles was compared with spray-chilled microparticles, pure and recrystallized samples. Spray dried microparticles and spray chilled microparticles exhibited decreased crystallinity and improved micromeritic properties. The dissolution of the spray dried microparticle and spray chilled particles were improved compared with recrystallized and pure sample of piroxicam. Consequently, it was believed that spray drying of piroxicam is a useful tool to improve dissolution but not in case of spray chilling. This may be due to the degradation of drug or variations in the resonance structure or could be due to minor distortion of bond angles. Hence, this spray drying technique can be used for formulation of tablets of piroxicam by direct compression with directly compressible tablet excipients. PMID:21589797

  4. Lysozyme-magnesium aluminum silicate microparticles: Molecular interaction, bioactivity and release studies.

    PubMed

    Kanjanakawinkul, Watchara; Medlicott, Natalie J; Rades, Thomas; Puttipipatkhachorn, Satit; Pongjanyakul, Thaned

    2015-09-01

    The objectives of this study were to investigate the adsorption behavior of lysozyme (LSZ) onto magnesium aluminum silicate (MAS) at various pHs and to characterize the LSZ-MAS microparticles obtained from the molecular interaction between LSZ and MAS. The results showed that LSZ could be bound onto the MAS layers at different pHs, leading to the formation of LSZ-MAS microparticles. The higher preparation pH permitted greater adsorption affinity but a lower adsorption capacity of LSZ onto MAS. LSZ could interact with MAS via hydrogen bonds and electrostatic forces, resulting in the formation of intercalated nanocomposites. The particle size, %LSZ adsorbed, and LSZ release rate of LSZ-MAS microparticles increased when the LSZ-MAS ratio was increased. The secondary structure of LSZ bound onto the MAS layers in microparticles prepared at various pHs was altered compared with that of native LSZ. Moreover, the LSZ extracted from microparticles prepared at pH 4 showed an obvious change in the tertiary structure, leading to a decrease in the biological activity of the LSZ released. These findings suggested that LSZ can strongly interact with MAS to form microparticles that may potentially be used as delivery systems for sustained protein release. PMID:26193680

  5. Cutting-Edge Analysis of Extracellular Microparticles using ImageStreamX Imaging Flow Cytometry

    PubMed Central

    Headland, Sarah E.; Jones, Hefin R.; D'Sa, Adelina S. V.; Perretti, Mauro; Norling, Lucy V.

    2014-01-01

    Interest in extracellular vesicle biology has exploded in the past decade, since these microstructures seem endowed with multiple roles, from blood coagulation to inter-cellular communication in pathophysiology. In order for microparticle research to evolve as a preclinical and clinical tool, accurate quantification of microparticle levels is a fundamental requirement, but their size and the complexity of sample fluids present major technical challenges. Flow cytometry is commonly used, but suffers from low sensitivity and accuracy. Use of Amnis ImageStreamX Mk II imaging flow cytometer afforded accurate analysis of calibration beads ranging from 1 μm to 20 nm; and microparticles, which could be observed and quantified in whole blood, platelet-rich and platelet-free plasma and in leukocyte supernatants. Another advantage was the minimal sample preparation and volume required. Use of this high throughput analyzer allowed simultaneous phenotypic definition of the parent cells and offspring microparticles along with real time microparticle generation kinetics. With the current paucity of reliable techniques for the analysis of microparticles, we propose that the ImageStreamX could be used effectively to advance this scientific field. PMID:24913598

  6. Microparticles Provide a Novel Biomarker To Predict Severe Clinical Outcomes of Dengue Virus Infection

    PubMed Central

    Punyadee, Nuntaya; Mairiang, Dumrong; Thiemmeca, Somchai; Komoltri, Chulaluk; Pan-ngum, Wirichada; Chomanee, Nusara; Charngkaew, Komgrid; Tangthawornchaikul, Nattaya; Limpitikul, Wannee; Vasanawathana, Sirijitt; Malasit, Prida

    2014-01-01

    ABSTRACT Shedding of microparticles (MPs) is a consequence of apoptotic cell death and cellular activation. Low levels of circulating MPs in blood help maintain homeostasis, whereas increased MP generation is linked to many pathological conditions. Herein, we investigated the role of MPs in dengue virus (DENV) infection. Infection of various susceptible cells by DENV led to apoptotic death and MP release. These MPs harbored a viral envelope protein and a nonstructural protein 1 (NS1) on their surfaces. Ex vivo analysis of clinical specimens from patients with infections of different degrees of severity at multiple time points revealed that MPs generated from erythrocytes and platelets are two major MP populations in the circulation of DENV-infected patients. Elevated levels of red blood cell-derived MPs (RMPs) directly correlated with DENV disease severity, whereas a significant decrease in platelet-derived MPs was associated with a bleeding tendency. Removal by mononuclear cells of complement-opsonized NS1–anti-NS1 immune complexes bound to erythrocytes via complement receptor type 1 triggered MP shedding in vitro, a process that could explain the increased levels of RMPs in severe dengue. These findings point to the multiple roles of MPs in dengue pathogenesis. They offer a potential novel biomarker candidate capable of differentiating dengue fever from the more serious dengue hemorrhagic fever. IMPORTANCE Dengue is the most important mosquito-transmitted viral disease in the world. No vaccines or specific treatments are available. Rapid diagnosis and immediate treatment are the keys to achieve a positive outcome. Dengue virus (DENV) infection, like some other medical conditions, changes the level and composition of microparticles (MPs), tiny bag-like structures which are normally present at low levels in the blood of healthy individuals. This study investigated how MPs in culture and patients' blood are changed in response to DENV infection. Infection of cells

  7. Large aperture scanning airborne lidar

    NASA Technical Reports Server (NTRS)

    Smith, J.; Bindschadler, R.; Boers, R.; Bufton, J. L.; Clem, D.; Garvin, J.; Melfi, S. H.

    1988-01-01

    A large aperture scanning airborne lidar facility is being developed to provide important new capabilities for airborne lidar sensor systems. The proposed scanning mechanism allows for a large aperture telescope (25 in. diameter) in front of an elliptical flat (25 x 36 in.) turning mirror positioned at a 45 degree angle with respect to the telescope optical axis. The lidar scanning capability will provide opportunities for acquiring new data sets for atmospheric, earth resources, and oceans communities. This completed facility will also make available the opportunity to acquire simulated EOS lidar data on a near global basis. The design and construction of this unique scanning mechanism presents exciting technological challenges of maintaining the turning mirror optical flatness during scanning while exposed to extreme temperatures, ambient pressures, aircraft vibrations, etc.

  8. The effect of a direct current field on the microparticle charge in the plasma afterglow

    SciTech Connect

    Wörner, L.; Ivlev, A. V.; Huber, P.; Hagl, T.; Thomas, H. M.; Morfill, G. E.; Couëdel, L.; Schwabe, M.; Mikikian, M.; Boufendi, L.; Skvortsov, A.; Lipaev, A. M.; Molotkov, V. I.; Petrov, O. F.; Fortov, V. E.

    2013-12-15

    Residual charges of individual microparticles forming dense clouds were measured in a RF discharge afterglow. Experiments were performed under microgravity conditions on board the International Space Station, which ensured particle levitation inside the gas volume after the plasma switch-off. The distribution of residual charges as well as the spatial distribution of charged particles across the cloud were analyzed by applying a low-frequency voltage to the electrodes and measuring amplitudes of the resulting particle oscillations. Upon “free decharging” conditions, the charge distribution had a sharp peak at zero and was rather symmetric (with charges concentrated between −10e and +10e), yet positively and negatively charged particles were homogeneously distributed over the cloud. However, when decharging evolved in the presence of an external DC field (applied shortly before the plasma switch-off) practically all residual charges were positive. In this case, the overall charge distribution had a sharp peak at about +15e and was highly asymmetric, while the spatial distribution exhibited a significant charge gradient along the direction of the applied DC field.

  9. In situ microparticle analysis of marine phytoplankton cells with infrared laser-based optical tweezers

    NASA Astrophysics Data System (ADS)

    Sonek, G. J.; Liu, Y.; Iturriaga, R. H.

    1995-11-01

    We describe the application of infrared optical tweezers to the in situ microparticle analysis of marine phytoplankton cells. A Nd:YAG laser (lambda=3D 1064 nm) trap is used to confine and manipulate single Nannochloris and Synechococcus cells in an enriched seawater medium while spectral fluorescence and Lorenz-Mie backscatter signals are simultaneously acquired under a variety of excitation and trapping conditions. Variations in the measured fluorescence intensities of chlorophyll a (Chl a) and phycoerythrin pigments in phytoplankton cells are observed. These variations are related, in part, to basic intrasample variability, but they also indicate that increasing ultraviolet-exposure time and infrared trapping power may have short-term effects on cellular physiology that are related to Chl a photobleaching and laser-induced heating, respectively. The use of optical tweezers to study the factors that affect marine cell physiology and the processes of absorption, scattering, and attenuation by individual cells, organisms, and particulate matter that contribute to optical closure on a microscopic scale are also described. (c)1995 Optical Society of America

  10. Microparticles That Form Immune Complexes as Modulatory Structures in Autoimmune Responses.

    PubMed

    Burbano, Catalina; Rojas, Mauricio; Vásquez, Gloria; Castaño, Diana

    2015-01-01

    Microparticles (MPs) are induced during apoptosis, cell activation, and even "spontaneous" release. Initially MPs were considered to be inert cellular products with no biological function. However, an extensive research and functional characterization have shown that the molecular composition and the effects of MPs depend upon the cellular background and the mechanism inducing them. They possess a wide spectrum of biological effects on intercellular communication by transferring different molecules able to modulate other cells. MPs interact with their target cells through different mechanisms: membrane fusion, macropinocytosis, and receptor-mediated endocytosis. However, when MPs remain in the extracellular milieu, they undergo modifications such as citrullination, glycosylation, and partial proteolysis, among others, becoming a source of neoantigens. In rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE), reports indicated elevated levels of MPs with different composition, content, and effects compared with those isolated from healthy individuals. MPs can also form immune complexes amplifying the proinflammatory response and tissue damage. Their early detection and characterization could facilitate an appropriate diagnosis optimizing the pharmacological strategies, in different diseases including cancer, infection, and autoimmunity. This review focuses on the current knowledge about MPs and their involvement in the immunopathogenesis of SLE and RA.

  11. Co-ordinated detection of microparticles using tunable resistive pulse sensing and fluorescence spectroscopy

    PubMed Central

    Hauer, Peter; Le Ru, Eric C.; Willmott, Geoff R.

    2015-01-01

    Tunable resistive pulse sensing (TRPS) has emerged as a useful tool for particle-by-particle detection and analysis of microparticles and nanoparticles as they pass through a pore in a thin stretchable membrane. We have adapted a TRPS device in order to conduct simultaneous optical measurements of particles passing through the pore. High-resolution fluorescence emission spectra have been recorded for individual 1.9 μm diameter particles at a sampling period of 4.3 ms. These spectra are time-correlated with RPS pulses in a current trace sampled every 20 μs. The flow rate through the pore, controlled by altering the hydrostatic pressure, determines the rate of particle detection. At pressures below 1 kPa, more than 90% of fluorescence and RPS events were matching. At higher pressures, some peaks were missed by the fluorescence technique due to the difference in sampling rates. This technique enhances the particle-by-particle specificity of conventional RPS measurements and could be useful for a range of particle characterization and bioanalysis applications. PMID:25713692

  12. Extensible Multiplex Real-time PCR of MicroRNA Using Microparticles

    PubMed Central

    Jung, Seungwon; Kim, Junsun; Lee, Dong Jin; Oh, Eun Hae; Lim, Hwasup; Kim, Kwang Pyo; Choi, Nakwon; Kim, Tae Song; Kim, Sang Kyung

    2016-01-01

    Multiplex quantitative real-time PCR (qPCR), which measures multiple DNAs in a given sample, has received significant attention as a mean of verifying the rapidly increasing genetic targets of interest in single phenotype. Here we suggest a readily extensible qPCR for the expression analysis of multiple microRNA (miRNA) targets using microparticles of primer-immobilized networks as discrete reactors. Individual particles, 200~500 μm in diameter, are identified by two-dimensional codes engraved into the particles and the non-fluorescent encoding allows high-fidelity acquisition of signal in real-time PCR. During the course of PCR, the amplicons accumulate in the volume of the particles with high reliability and amplification efficiency over 95%. In a quick assay comprising of tens of particles holding different primers, each particle brings the independent real-time amplification curve representing the quantitative information of each target. Limited amount of sample was analyzed simultaneously in single chamber through this highly multiplexed qPCR; 10 kinds of miRNAs from purified extracellular vesicles (EVs). PMID:26964639

  13. Flow bioreactor design for quantitative measurements over endothelial cells using micro-particle image velocimetry

    NASA Astrophysics Data System (ADS)

    Leong, Chia Min; Voorhees, Abram; Nackman, Gary B.; Wei, Timothy

    2013-04-01

    Mechanotransduction in endothelial cells (ECs) is a highly complex process through which cells respond to changes in hemodynamic loading by generating biochemical signals involving gene and protein expression. To study the effects of mechanical loading on ECs in a controlled fashion, different in vitro devices have been designed to simulate or replicate various aspects of these physiological phenomena. This paper describes the design, use, and validation of a flow chamber which allows for spatially and temporally resolved micro-particle image velocimetry measurements of endothelial surface topography and stresses over living ECs immersed in pulsatile flow. This flow chamber also allows the study of co-cultures (i.e., ECs and smooth muscle cells) and the effect of different substrates (i.e., coverslip and/or polyethylene terepthalate (PET) membrane) on cellular response. In this report, the results of steady and pulsatile flow on fixed endothelial cells seeded on PET membrane and coverslip, respectively, are presented. Surface topography of ECs is computed from multiple two-dimensional flow measurements. The distributions of shear stress and wall pressure on each individual cell are also determined and the importance of both types of stress in cell remodeling is highlighted.

  14. Microparticles That Form Immune Complexes as Modulatory Structures in Autoimmune Responses.

    PubMed

    Burbano, Catalina; Rojas, Mauricio; Vásquez, Gloria; Castaño, Diana

    2015-01-01

    Microparticles (MPs) are induced during apoptosis, cell activation, and even "spontaneous" release. Initially MPs were considered to be inert cellular products with no biological function. However, an extensive research and functional characterization have shown that the molecular composition and the effects of MPs depend upon the cellular background and the mechanism inducing them. They possess a wide spectrum of biological effects on intercellular communication by transferring different molecules able to modulate other cells. MPs interact with their target cells through different mechanisms: membrane fusion, macropinocytosis, and receptor-mediated endocytosis. However, when MPs remain in the extracellular milieu, they undergo modifications such as citrullination, glycosylation, and partial proteolysis, among others, becoming a source of neoantigens. In rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE), reports indicated elevated levels of MPs with different composition, content, and effects compared with those isolated from healthy individuals. MPs can also form immune complexes amplifying the proinflammatory response and tissue damage. Their early detection and characterization could facilitate an appropriate diagnosis optimizing the pharmacological strategies, in different diseases including cancer, infection, and autoimmunity. This review focuses on the current knowledge about MPs and their involvement in the immunopathogenesis of SLE and RA. PMID:26300590

  15. Flow bioreactor design for quantitative measurements over endothelial cells using micro-particle image velocimetry.

    PubMed

    Leong, Chia Min; Voorhees, Abram; Nackman, Gary B; Wei, Timothy

    2013-04-01

    Mechanotransduction in endothelial cells (ECs) is a highly complex process through which cells respond to changes in hemodynamic loading by generating biochemical signals involving gene and protein expression. To study the effects of mechanical loading on ECs in a controlled fashion, different in vitro devices have been designed to simulate or replicate various aspects of these physiological phenomena. This paper describes the design, use, and validation of a flow chamber which allows for spatially and temporally resolved micro-particle image velocimetry measurements of endothelial surface topography and stresses over living ECs immersed in pulsatile flow. This flow chamber also allows the study of co-cultures (i.e., ECs and smooth muscle cells) and the effect of different substrates (i.e., coverslip and∕or polyethylene terepthalate (PET) membrane) on cellular response. In this report, the results of steady and pulsatile flow on fixed endothelial cells seeded on PET membrane and coverslip, respectively, are presented. Surface topography of ECs is computed from multiple two-dimensional flow measurements. The distributions of shear stress and wall pressure on each individual cell are also determined and the importance of both types of stress in cell remodeling is highlighted.

  16. Seroprevalence of Mycoplasma pneumoniae in HIV-infected patients using a microparticle agglutination test.

    PubMed

    Shankar, Esaki Muthu; Kumarasamy, Nagalingeswaran; Balakrishnan, Pachamuthu; Vengatesan, A; Kownhar, Hayath; Solomon, Suniti; Rao, Usha Anand

    2006-06-01

    Mycoplasma pneumoniae is increasingly recognized as a common and important pathogen in community settings, and is responsible for various pulmonary and extrapulmonary conditions in the normal population. However, the seroepidemiology of acute M. pneumoniae infection in HIV-infected individuals is still unclear worldwide. This study examined the seroprevalence of antibodies to M. pneumoniae in HIV-infected patients admitted with respiratory complaints at a tertiary AIDS care centre in Chennai, India. A commercial gelatin microparticle agglutination test (Serodia-Myco II, Fujirebio) was used for the determination of antibodies against M. pneumoniae in acute serum specimens. Of the 200 HIV-infected patients with underlying pulmonary conditions tested, 34 (17 % positivity; 95 % CI 12-23 %) had antibodies specific to M. pneumoniae, while among the 40 patients with no underlying pulmonary symptoms, five (12.5 % positivity; 95 % CI 4-27 %) had evidence of anti-M. pneumoniae antibody. This shows that the incidence of M. pneumoniae seropositivity is greater in patients with underlying pulmonary complaints. Most positive titres were found in the age group 28-37 years in the symptomatic and symptom-free groups (64.7 and 60 %, respectively). The positive titres ranged from 40 to >20 480. High titres (> or =320) were found in 10 out of the 39 patients (25.6 %). This seroprevalence study reports a 16.2 % prevalence of M. pneumoniae infections in HIV-infected patients by a particle agglutination test.

  17. The effect of a direct current field on the microparticle charge in the plasma afterglow

    NASA Astrophysics Data System (ADS)

    Wörner, L.; Ivlev, A. V.; Couëdel, L.; Huber, P.; Schwabe, M.; Hagl, T.; Mikikian, M.; Boufendi, L.; Skvortsov, A.; Lipaev, A. M.; Molotkov, V. I.; Petrov, O. F.; Fortov, V. E.; Thomas, H. M.; Morfill, G. E.

    2013-12-01

    Residual charges of individual microparticles forming dense clouds were measured in a RF discharge afterglow. Experiments were performed under microgravity conditions on board the International Space Station, which ensured particle levitation inside the gas volume after the plasma switch-off. The distribution of residual charges as well as the spatial distribution of charged particles across the cloud were analyzed by applying a low-frequency voltage to the electrodes and measuring amplitudes of the resulting particle oscillations. Upon "free decharging" conditions, the charge distribution had a sharp peak at zero and was rather symmetric (with charges concentrated between -10e and +10e), yet positively and negatively charged particles were homogeneously distributed over the cloud. However, when decharging evolved in the presence of an external DC field (applied shortly before the plasma switch-off) practically all residual charges were positive. In this case, the overall charge distribution had a sharp peak at about +15e and was highly asymmetric, while the spatial distribution exhibited a significant charge gradient along the direction of the applied DC field.

  18. Microparticles That Form Immune Complexes as Modulatory Structures in Autoimmune Responses

    PubMed Central

    Burbano, Catalina; Rojas, Mauricio; Vásquez, Gloria; Castaño, Diana

    2015-01-01

    Microparticles (MPs) are induced during apoptosis, cell activation, and even “spontaneous” release. Initially MPs were considered to be inert cellular products with no biological function. However, an extensive research and functional characterization have shown that the molecular composition and the effects of MPs depend upon the cellular background and the mechanism inducing them. They possess a wide spectrum of biological effects on intercellular communication by transferring different molecules able to modulate other cells. MPs interact with their target cells through different mechanisms: membrane fusion, macropinocytosis, and receptor-mediated endocytosis. However, when MPs remain in the extracellular milieu, they undergo modifications such as citrullination, glycosylation, and partial proteolysis, among others, becoming a source of neoantigens. In rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE), reports indicated elevated levels of MPs with different composition, content, and effects compared with those isolated from healthy individuals. MPs can also form immune complexes amplifying the proinflammatory response and tissue damage. Their early detection and characterization could facilitate an appropriate diagnosis optimizing the pharmacological strategies, in different diseases including cancer, infection, and autoimmunity. This review focuses on the current knowledge about MPs and their involvement in the immunopathogenesis of SLE and RA. PMID:26300590

  19. Microparticles in the blood of patients with systemic lupus erythematosus (SLE): phenotypic characterization and clinical associations

    PubMed Central

    Mobarrez, Fariborz; Vikerfors, Anna; Gustafsson, Johanna T.; Gunnarsson, Iva; Zickert, Agneta; Larsson, Anders; Pisetsky, David S.; Wallén, Håkan; Svenungsson, Elisabet

    2016-01-01

    Systemic lupus erythematosus (SLE) is a prototypic autoimmune disease characterized by circulating autoantibodies and the formation of immune complexes. In these responses, the selecting self-antigens likely derive from the remains of dead and dying cells, as well as from disturbances in clearance. During cell death/activation, microparticles (MPs) can be released to the circulation. Previous MP studies in SLE have been limited in size and differ regarding numbers and phenotypes. Therefore, to characterize MPs more completely, we investigated 280 SLE patients and 280 individually matched controls. MPs were measured with flow cytometry and phenotyped according to phosphatidylserine expression (PS+/PS−), cellular origin and inflammatory markers. MPs, regardless of phenotype, are 2–10 times more abundant in SLE blood compared to controls. PS− MPs predominated in SLE, but not in controls (66% vs. 42%). Selectively in SLE, PS− MPs were more numerous in females and smokers. MP numbers decreased with declining renal function, but no clear association with disease activity was observed. The striking abundance of MPs, especially PS− MPs, suggests a generalized disturbance in SLE. MPs may be regarded as “liquid biopsies” to assess the production and clearance of dead, dying and activated cells, i.e. pivotal events for SLE pathogenesis. PMID:27777414

  20. Magnetic airborne survey - geophysical flight

    NASA Astrophysics Data System (ADS)

    de Barros Camara, Erick; Nei Pereira Guimarães, Suze

    2016-06-01

    This paper provides a technical review process in the area of airborne acquisition of geophysical data, with emphasis for magnetometry. In summary, it addresses the calibration processes of geophysical equipment as well as the aircraft to minimize possible errors in measurements. The corrections used in data processing and filtering are demonstrated with the same results as well as the evolution of these techniques in Brazil and worldwide.

  1. Formulation and Evaluation of In-vitro Characterization of Gastic-Mucoadhesive Microparticles/Discs Containing Metformin Hydrochloride

    PubMed Central

    Khonsari, Fatemeh; Zakeri-Milani, Parvin; Jelvehgari, Mitra

    2014-01-01

    The present study involves preparation and evaluation of gastric-mucoadhesive microparticles with Metformin Hydrochloride as model drug for prolongation of gastric residence time. The microparticles were prepared by the emulsification solvent evaporation technique using polymers of Carbomer 934p (CP) and Ethylcellulose (EC). The microparticles were prepared by emulsion solvent evaporation method (O1/O2). Disc formulations were prepared by direct compression technique from microparticles. In the current study, gastric-mucoadhesive microparticles with different polymers ratios (CP:EC) were prepared and were characterized by encapsulation efficiency, particle size, flowability, mucoadhesive property and drug release studies. The best polymers ratio was 1:3 (F2) with Carbomer 934p (as mucoadhesive polymer) and ethylcellulose (as retardant polymer), respectively. The production yield microparticles F2 showed 98.80%, mean particle size 933.25 µm and loading efficiency %98.44. The results were found that microparticle discs prepared had slower release than microparticles (p > o.o5). The microparticles exhibited very good percentage of mucoadhesion and flowability properties. The release of drug was prolonged to 8 h (71.65-82.22%) when incorporated into mucoadhesive microparticles. The poor bioavailability of metformine is attributed to short retention of its dosage form at the absorption sites (in upper gastrointestinal tract). The results of mucoadhesion study showed better retention of metformine microparticles (8 h) in duodenal and jejunum regions of intestine (F1, 1:2 ratio of CP:EC). Therefore, it may be concluded that drug loaded gastric-mucoadhesive microparticles are a suitable delivery system for metformin hydrochloride, and may be used for effective management of NIDDM (Non Insulin Dependent Diabetes Mellitus). PMID:24734057

  2. Preparation of Biocatalytic Microparticles by Interfacial Self-Assembly of Enzyme-Nanoparticle Conjugates Around a Cross-Linkable Core.

    PubMed

    Andler, S M; Wang, L-S; Goddard, J M; Rotello, V M

    2016-01-01

    Rational design of hierarchical interfacial assembly of reusable biocatalytic microparticles is described in this chapter. Specifically, purified enzymes and functionalized nanoparticles are electrostatically assembled at the interface of cross-linked microparticles which are formed through ring opening metathesis polymerization. The diameters of microparticle assemblies average 10μm, and they show enhanced kinetic efficiency as well as improved stability against heat, pH, and solvent denaturation when compared to stabilities of the corresponding native enzymes.

  3. Formation of peptides from amino acids by single or multiple additions of ATP to suspensions of nucleoproteinoid microparticles

    NASA Technical Reports Server (NTRS)

    Nakashima, T.; Fox, S. W.

    1981-01-01

    The synthesis of peptides from individual amino acids or pairs of amino acids and ATP in the presence of catalysis by nucleoproteinoid microparticles is investigated. Experiments were performed with suspensions formed from the condensation of lysine-rich and acidic proteinoids with polyadenylic acid, to which were added glycine, phenylalanine, proline, lysine or glycine-phenylalanine mixtures, and ATP either at once or serially. Peptide yields are found to be greatest for equal amounts of acidic and basic proteinoids. The addition of imidazole is found to alter the preference of glycine-phenylalanine mixtures to form mixed heteropeptides rather than homopeptides. A rapid ATP decay in the peptide synthesis reaction is observed, and a greater yield is obtained for repeated small additions than for a single addition of ATP. The experimental system has properties similar to modern cells, and represents an organizational unit ready for the evolution of associated biochemical pathways.

  4. Airborne particulate matter in spacecraft

    NASA Technical Reports Server (NTRS)

    1988-01-01

    Acceptability limits and sampling and monitoring strategies for airborne particles in spacecraft were considered. Based on instances of eye and respiratory tract irritation reported by Shuttle flight crews, the following acceptability limits for airborne particles were recommended: for flights of 1 week or less duration (1 mg/cu m for particles less than 10 microns in aerodynamic diameter (AD) plus 1 mg/cu m for particles 10 to 100 microns in AD); and for flights greater than 1 week and up to 6 months in duration (0.2 mg/cu m for particles less than 10 microns in AD plus 0.2 mg/cu m for particles 10 to 100 microns in AD. These numerical limits were recommended to aid in spacecraft atmosphere design which should aim at particulate levels that are a low as reasonably achievable. Sampling of spacecraft atmospheres for particles should include size-fractionated samples of 0 to 10, 10 to 100, and greater than 100 micron particles for mass concentration measurement and elementary chemical analysis by nondestructive analysis techniques. Morphological and chemical analyses of single particles should also be made to aid in identifying airborne particulate sources. Air cleaning systems based on inertial collection principles and fine particle collection devices based on electrostatic precipitation and filtration should be considered for incorporation into spacecraft air circulation systems. It was also recommended that research be carried out in space in the areas of health effects and particle characterization.

  5. Tunneling holes in microparticles to facilitate the transport of lithium ions for high volumetric density batteries

    NASA Astrophysics Data System (ADS)

    Zhu, Jian; Ng, K. Y. Simon; Deng, Da

    2015-08-01

    Microscale materials generally have a higher tap density than that of random nanoparticles. Therefore, microparticles have been attracting much attention for application as high volumetric density electrodes for lithium ion batteries. However, microparticles have much longer electrolyte diffusion and Li-ion migration length and less accessibility to the electrolyte than that of nanoparticles. Therefore, it will be interesting to tunnel-holes in the high volumetric density microparticles to facilitate the reversible storage of lithium ions. Here, tunnel-like holes were generated in microparticles to dramatically increase the accessibility of the active materials to facilitate the lithium ion transfer. A plausible formation mechanism to explain the generation of tunnel-like holes was proposed based on time-course experiments and intensive characterization. Impressively, the as-prepared microbeads with tunnels demonstrated dramatically improved performance compared to the solid microbeads without tunnels in lithium ion storage. The microparticles with tunnels could achieve comparable electrochemical performances to those nanoparticles reported in the literature, suggesting that microparticles, properly tuned, could be promising candidates as negative electrodes for lithium-ion batteries and worthy of further studies. We also directly measured the volumetric density of the microparticles. We would like to highlight that a superior volumetric capacity of 514 mA h cm-3 has been achieved. We hope to promote more frequent use of the unit mA h cm-3 in addition to the conventional unit mA h g-1 in the battery community.Microscale materials generally have a higher tap density than that of random nanoparticles. Therefore, microparticles have been attracting much attention for application as high volumetric density electrodes for lithium ion batteries. However, microparticles have much longer electrolyte diffusion and Li-ion migration length and less accessibility to the

  6. Drug release mechanisms of chemically cross-linked albumin microparticles: effect of the matrix erosion.

    PubMed

    Sitta, Danielly L A; Guilherme, Marcos R; da Silva, Elisangela P; Valente, Artur J M; Muniz, Edvani C; Rubira, Adley F

    2014-10-01

    Albumin (BSA) microparticles were developed as a biotechnological alternative for drug delivery. Vitamin B12 (Vit-B12) was used as a model drug. The microparticles were obtained from maleic anhydride-functionalized BSA and N',N'-dimethylacrylamide (DMAAm) in a W/O emulsion without and with PVA. The microparticles produced at 15min of stirring without PVA showed the best results in terms of size, homogeneity, and sphericity. In such a case, BSA played a role as a surface active agent, replacing PVA. For longer stirring times, BSA was unable to act as an emulsifier. These microparticles showed an uncommon release profile, consisting of a two-step release mechanism, at the pH range studied. Considering that a two-step release mechanism is occurring, the experimental data were adjusted by applying modified power law and Weibull equations in order to describe release mechanism n and release rate constant k, respectively. Each one of the release stages was related to a specific value of n and k. The second stage was driven by a super case II transport mechanism, as a result of diffusion, macromolecular relaxation, and erosion. A third model, described by Hixson-Crowell, confirmed the erosion mechanism. Vit-B12 diffusion kinetics in aqueous solutions (i.e., without the microparticles) follows a one-step process, being k dependent on the pH, confirming that the two-step release mechanism is a characteristic profile of the developed microparticles. The microparticles released only 2.70% of their initial drug load at pH 2, and 58.53% at pH 10. PMID:25087021

  7. Activity of daptomycin- and vancomycin-loaded poly-epsilon-caprolactone microparticles against mature staphylococcal biofilms.

    PubMed

    Ferreira, Inês Santos; Bettencourt, Ana F; Gonçalves, Lídia M D; Kasper, Stefanie; Bétrisey, Bertrand; Kikhney, Judith; Moter, Annette; Trampuz, Andrej; Almeida, António J

    2015-01-01

    The aim of the present study was to develop novel daptomycin-loaded poly-epsilon-caprolactone (PCL) microparticles with enhanced antibiofilm activity against mature biofilms of clinically relevant bacteria, methicillin-resistant Staphylococcus aureus (MRSA) and polysaccharide intercellular adhesin-positive Staphylococcus epidermidis. Daptomycin was encapsulated into PCL microparticles by a double emulsion-solvent evaporation method. For comparison purposes, formulations containing vancomycin were also prepared. Particle morphology, size distribution, encapsulation efficiency, surface charge, thermal behavior, and in vitro release were assessed. All formulations exhibited a spherical morphology, micrometer size, and negative surface charge. From a very early time stage, the released concentrations of daptomycin and vancomycin were higher than the minimal inhibitory concentration and continued so up to 72 hours. Daptomycin presented a sustained release profile with increasing concentrations of the drug being released up to 72 hours, whereas the release of vancomycin stabilized at 24 hours. The antibacterial activity of the microparticles was assessed by isothermal microcalorimetry against planktonic and sessile MRSA and S. epidermidis. Regarding planktonic bacteria, daptomycin-loaded PCL microparticles presented the highest antibacterial activity against both strains. Isothermal microcalorimetry also revealed that lower concentrations of daptomycin-loaded microparticles were required to completely inhibit the recovery of mature MRSA and S. epidermidis biofilms. Further characterization of the effect of daptomycin-loaded PCL microparticles on mature biofilms was performed by fluorescence in situ hybridization. Fluorescence in situ hybridization showed an important reduction in MRSA biofilm, whereas S. epidermidis biofilms, although inhibited, were not eradicated. In addition, an important attachment of the microparticles to MRSA and S. epidermidis biofilms was

  8. Drying Using Supercritical Fluid Technology as a Potential Method for Preparation of Chitosan Aerogel Microparticles.

    PubMed

    Obaidat, Rana M; Tashtoush, Bassam M; Bayan, Mohammad F; Al Bustami, Rana T; Alnaief, Mohammad

    2015-12-01

    Supercritical fluid technology offers several advantages in preparation of microparticles. These include uniformity in particle size, morphology, and drug distribution without degradation of the product. One of the recent advantages is preparation of porous aerogel carrier with proper aerodynamic properties. In this study, we aimed to prepare chitosan aerogel microparticles using supercritical fluid (SCF) technology and compare that with microparticles produced by freeze drying (FD). Loading the prepared carriers with a model drug (salbutamol) was also performed. Comparisons of the particle properties and physicochemical characterizations were undertaken by evaluating particle size, density, specific surface area, and porosity. In vitro drug release studies were also investigated. The effect of many variables, such as molecular weight of chitosan oligomers, concentrations of chitosan, and concentrations of tripolyphosphate on the release, were also investigated. Chitosan aerogels were efficiently produced by SCF technology with an average particle size of 10 μm with a tapped density values around 0.12 g/mL, specific surface area (73-103) m(2)/g, and porosity (0.20-0.29) cc/g. Whereas, microparticles produced by FD method were characterized as cryogels with larger particle size (64 microns) with clear cracking at the surface. Sustained release profile was achieved for all prepared microparticles of salbutamol produced by the aforementioned methods as compared with pure drug. The results also demonstrates that chitosan molecular weight, polymer concentration, and tripolyphosphate concentration affected the release profile of salbutamol from the prepared microparticles. In conclusion, SCF technology was able to produce chitosan aerogel microparticles loaded with salbutamol that could be suitable for pulmonary drug delivery system.

  9. Activity of daptomycin- and vancomycin-loaded poly-epsilon-caprolactone microparticles against mature staphylococcal biofilms

    PubMed Central

    Ferreira, Inês Santos; Bettencourt, Ana F; Gonçalves, Lídia MD; Kasper, Stefanie; Bétrisey, Bertrand; Kikhney, Judith; Moter, Annette; Trampuz, Andrej; Almeida, António J

    2015-01-01

    The aim of the present study was to develop novel daptomycin-loaded poly-epsilon-caprolactone (PCL) microparticles with enhanced antibiofilm activity against mature biofilms of clinically relevant bacteria, methicillin-resistant Staphylococcus aureus (MRSA) and polysaccharide intercellular adhesin-positive Staphylococcus epidermidis. Daptomycin was encapsulated into PCL microparticles by a double emulsion-solvent evaporation method. For comparison purposes, formulations containing vancomycin were also prepared. Particle morphology, size distribution, encapsulation efficiency, surface charge, thermal behavior, and in vitro release were assessed. All formulations exhibited a spherical morphology, micrometer size, and negative surface charge. From a very early time stage, the released concentrations of daptomycin and vancomycin were higher than the minimal inhibitory concentration and continued so up to 72 hours. Daptomycin presented a sustained release profile with increasing concentrations of the drug being released up to 72 hours, whereas the release of vancomycin stabilized at 24 hours. The antibacterial activity of the microparticles was assessed by isothermal microcalorimetry against planktonic and sessile MRSA and S. epidermidis. Regarding planktonic bacteria, daptomycin-loaded PCL microparticles presented the highest antibacterial activity against both strains. Isothermal microcalorimetry also revealed that lower concentrations of daptomycin-loaded microparticles were required to completely inhibit the recovery of mature MRSA and S. epidermidis biofilms. Further characterization of the effect of daptomycin-loaded PCL microparticles on mature biofilms was performed by fluorescence in situ hybridization. Fluorescence in situ hybridization showed an important reduction in MRSA biofilm, whereas S. epidermidis biofilms, although inhibited, were not eradicated. In addition, an important attachment of the microparticles to MRSA and S. epidermidis biofilms was

  10. The mechanism of PLA microparticle formation by water-in-oil-in-water solvent evaporation method.

    PubMed

    Chen, J L; Chiang, C H; Yeh, M K

    2002-01-01

    Microparticles containing ovalbumin as a model protein drug were prepared using poly(L-lactide; PLA) with a water-in-oil-in-water emulsion/solvent evaporation technique. The dispersed phase was PLA dissolved in dichloromethane (DCM), and the continuous phase was water-containing polyvinyl pyrolidone (PVP) as stabilizer with sodium chloride. Microparticle characteristics, loading efficiencies, protein distribution in microparticles, and in-vitro release properties were investigated. The OVA leaking into the continuous phase during the formation of microparticle by DCM evaporation was also evaluated. Results show that OVA was successfully entrapped in the microparticles with trapping efficiencies up to 72%, loading level 8.7% w/v, and particle size 14 microm. The semi-solid suspension changes to a solid particle happened during a 10-min period. Total protein-leaking amount was reduced after addition of NaCl in the continuous aqueous phase, which resulted from reducing the solidification time and protein-leaking rate. Using 5% w/v NaCl in the continuous phase resulted in higher loading content (87.2 +/- 1.0 microg/mg), and loading efficiency (72.2%), which resulted from more protein in the deeper layer (50.2 +/- 2.3 microg/mg) and higher microparticle yield (75.2%) than without NaCl (loading content: 74.0 +/- 1.0 microg/mg; loading efficiency 51.8%; deeper layer content: 18.3 +/- 3.5 microg/mg; yield: 63.6%). These results constitute a step forward in the improvement of existing technology in controlling protein encapsulation and delivery from microparticles prepared by the multiple emulsion solvent evaporation method. PMID:12022499

  11. Activity of daptomycin- and vancomycin-loaded poly-epsilon-caprolactone microparticles against mature staphylococcal biofilms.

    PubMed

    Ferreira, Inês Santos; Bettencourt, Ana F; Gonçalves, Lídia M D; Kasper, Stefanie; Bétrisey, Bertrand; Kikhney, Judith; Moter, Annette; Trampuz, Andrej; Almeida, António J

    2015-01-01

    The aim of the present study was to develop novel daptomycin-loaded poly-epsilon-caprolactone (PCL) microparticles with enhanced antibiofilm activity against mature biofilms of clinically relevant bacteria, methicillin-resistant Staphylococcus aureus (MRSA) and polysaccharide intercellular adhesin-positive Staphylococcus epidermidis. Daptomycin was encapsulated into PCL microparticles by a double emulsion-solvent evaporation method. For comparison purposes, formulations containing vancomycin were also prepared. Particle morphology, size distribution, encapsulation efficiency, surface charge, thermal behavior, and in vitro release were assessed. All formulations exhibited a spherical morphology, micrometer size, and negative surface charge. From a very early time stage, the released concentrations of daptomycin and vancomycin were higher than the minimal inhibitory concentration and continued so up to 72 hours. Daptomycin presented a sustained release profile with increasing concentrations of the drug being released up to 72 hours, whereas the release of vancomycin stabilized at 24 hours. The antibacterial activity of the microparticles was assessed by isothermal microcalorimetry against planktonic and sessile MRSA and S. epidermidis. Regarding planktonic bacteria, daptomycin-loaded PCL microparticles presented the highest antibacterial activity against both strains. Isothermal microcalorimetry also revealed that lower concentrations of daptomycin-loaded microparticles were required to completely inhibit the recovery of mature MRSA and S. epidermidis biofilms. Further characterization of the effect of daptomycin-loaded PCL microparticles on mature biofilms was performed by fluorescence in situ hybridization. Fluorescence in situ hybridization showed an important reduction in MRSA biofilm, whereas S. epidermidis biofilms, although inhibited, were not eradicated. In addition, an important attachment of the microparticles to MRSA and S. epidermidis biofilms was

  12. Activation of the Inflammasome and Enhanced Migration of Microparticle-Stimulated Dendritic Cells to the Draining Lymph Node

    PubMed Central

    Meraz, Ismail M.; Melendez, Brenda; Gu, Jianhua; Wong, Stephen T.C.; Liu, Xuewu; Andersson, Helen A.; Serda, Rita E.

    2012-01-01

    Porous silicon microparticles presenting pathogen-associated molecular patterns mimic pathogens, enhancing internalization of the microparticles and activation of antigen presenting dendritic cells. We demonstrate abundant uptake of microparticles bound by the TLR-4 ligands LPS and MPL by murine bone marrow-derived dendritic cells (BMDC). Labeled microparticles induce concentration-dependent production of IL-1β, with inhibition by the caspase inhibitor Z-VAD-FMK supporting activation of the NLRP3-dependent inflammasome. Inoculation of BALB/c mice with ligand-bound microparticles induces a significant increase in circulating levels of IL-1β, TNF-α, and IL-6. Stimulation of BMDC with ligand-bound microparticles increases surface expression of co-stimulatory and MHC molecules, and enhances migration of BMDC to the draining lymph node. LPS-microparticles stimulate in vivo C57BL/6 BMDC and OT-1 transgenic T cell interactions in the presence of OVA SIINFEKL peptide in lymph nodes, with intact nodes imaged using two-photon microscopy. Formation of in vivo and in vitro immunological synapses between BMDC, loaded with OVA peptide and LPS-microparticles, and OT-1 T cells are presented, as well as elevated intracellular interferon gamma levels in CD8+ T cells stimulated by BMDC carrying peptide-loaded microparticles. In short, ligand-bound microparticles enhance 1) phagocytosis of microparticles; 2) BMDC inflammasome activation and up-regulation of co-stimulatory and MHC molecules; 3) cellular migration of BMDC to lymphatic tissue; and 4) cellular interactions leading to T cell activation in the presence of antigen. PMID:22680980

  13. Geophex airborne unmanned survey system

    SciTech Connect

    Won, I.J.; Taylor, D.W.A.

    1995-03-01

    The purpose of this effort is to design, construct, and evaluate a portable, remotely-piloted, airborne, geophysical survey system. This nonintrusive system will provide {open_quotes}stand-off{close_quotes} capability to conduct surveys and detect buried objects, structures, and conditions of interest at hazardous locations. This system permits two operators to rapidly conduct geophysical characterization of hazardous environmental sites. During a survey, the operators remain remote from, but within visual distance, of, the site. The sensor system never contacts the Earth, but can be positioned near the ground so that weak anomalies can be detected.

  14. Airborne wavemeter validation and calibration

    NASA Technical Reports Server (NTRS)

    Goad, Joseph H., Jr.; Rinsland, Pamela L.; Kist, Edward H., Jr.; Geier, Erika B.; Banziger, Curtis G.

    1992-01-01

    This manuscript outlines a continuing effort to validate and verify the performance of an airborne autonomous wavemeter for tuning solid state lasers to a desired wavelength. The application is measuring the vertical profiles of atmospheric water vapor using a differential absorption lidar (DIAL) technique. Improved wavemeter performance data for varying ambient temperatures are presented. This resulted when the electronic grounding and shielding were improved. The results with short pulse duration lasers are also included. These lasers show that similar performance could be obtained with lasers operating in the continuous and the pulsed domains.

  15. Geophex Airborne Unmanned Survey System

    SciTech Connect

    Won, I.J.; Keiswetter, D.

    1995-10-01

    The purpose of this effort is to design, construct, and evaluate a portable, remotely-piloted, airborne, geophysical survey system. This non-intrusive system will provide {open_quotes}stand-off{close_quotes} capability to conduct surveys and detect buried objects, structures, and conditions of interest at hazardous locations. This system permits rapid geophysical characterization of hazardous environmental sites. During a survey, the operators remain remote from, but within visual distance of, the site. The sensor system never contacts the Earth, but can be positioned near the ground so that weak geophysical anomalies can be detected.

  16. Airborne Research Experience for Educators

    NASA Astrophysics Data System (ADS)

    Costa, V. B.; Albertson, R.; Smith, S.; Stockman, S. A.

    2009-12-01

    The Airborne Research Experience for Educators (AREE) Program, conducted by the NASA Dryden Flight Research Center Office of Education in partnership with the AERO Institute, NASA Teaching From Space Program, and California State University Fullerton, is a complete end-to-end residential research experience in airborne remote sensing and atmospheric science. The 2009 program engaged ten secondary educators who specialize in science, technology, engineering or mathematics in a 6-week Student Airborne Research Program (SARP) offered through NSERC. Educators participated in collection of in-flight remote sensor data during flights aboard the NASA DC-8 as well as in-situ research on atmospheric chemistry (bovine emissions of methane); algal blooms (remote sensing to determine location and degree of blooms for further in-situ analysis); and crop classification (exploration of how drought conditions in Central California have impacted almond and cotton crops). AREE represents a unique model of the STEM teacher-as-researcher professional development experience because it asks educators to participate in a research experience and then translate their experiences into classroom practice through the design, implementation, and evaluation of instructional materials that emphasize the scientific research process, inquiry-based investigations, and manipulation of real data. Each AREE Master Educator drafted a Curriculum Brief, Teachers Guide, and accompanying resources for a topic in their teaching assignment Currently, most professional development programs offer either a research experience OR a curriculum development experience. The dual nature of the AREE model engaged educators in both experiences. Educators’ content and pedagogical knowledge of STEM was increased through the review of pertinent research articles during the first week, attendance at lectures and workshops during the second week, and participation in the airborne and in-situ research studies, data

  17. Cyberinfrastructure for Airborne Sensor Webs

    NASA Technical Reports Server (NTRS)

    Freudinger, Lawrence C.

    2009-01-01

    Since 2004 the NASA Airborne Science Program has been prototyping and using infrastructure that enables researchers to interact with each other and with their instruments via network communications. This infrastructure uses satellite links and an evolving suite of applications and services that leverage open-source software. The use of these tools has increased near-real-time situational awareness during field operations, resulting in productivity improvements and the collection of better data. This paper describes the high-level system architecture and major components, with example highlights from the use of the infrastructure. The paper concludes with a discussion of ongoing efforts to transition to operational status.

  18. Requirements for airborne vector gravimetry

    NASA Technical Reports Server (NTRS)

    Schwarz, K. P.; Colombo, O.; Hein, G.; Knickmeyer, E. T.

    1992-01-01

    The objective of airborne vector gravimetry is the determination of the full gravity disturbance vector along the aircraft trajectory. The paper briefly outlines the concept of this method using a combination of inertial and GPS-satellite data. The accuracy requirements for users in geodesy and solid earth geophysics, oceanography and exploration geophysics are then specified. Using these requirements, accuracy specifications for the GPS subsystem and the INS subsystem are developed. The integration of the subsystems and the problems connected with it are briefly discussed and operational methods are indicated that might reduce some of the stringent accuracy requirements.

  19. Biological monitoring of airborne pollution

    SciTech Connect

    Ditz, D.W. )

    1990-01-01

    Common plants such as grasses, mosses, and even goldenrod may turn out to have a new high-tech role as monitors of airborne pollution from solid waste incinerators. Certain plants that respond to specific pollutants can provide continuous surveillance of air quality over long periods of time: they are bio-indicators. Other species accumulate pollutants and can serve as sensitive indicators of pollutants and of food-chain contamination: they are bio-accumulators. Through creative use of these properties, biological monitoring can provide information that cannot be obtained by current methods such as stack testing.

  20. Toolsets for Airborne Data - URS and New Documentation

    Atmospheric Science Data Center

    2015-03-23

    ... airborne field missions, documentation, and EOSDIS User Registration System (URS) authentication. This web application features an intuitive user interface for variable selection across different airborne field studies and ...

  1. A Biodegradation Study of SBA-15 Microparticles in Simulated Body Fluid and in Vivo.

    PubMed

    Choi, Youngjin; Lee, Jung Eun; Lee, Jung Heon; Jeong, Ji Hoon; Kim, Jaeyun

    2015-06-16

    Mesoporous silica has received considerable attention as a drug delivery vehicle because of its large surface area and large pore volume for loading drugs and large biomolecules. Recently, mesoporous silica microparticles have shown potential as a three-dimensional vaccine platform for modulating dendritic cells via spontaneous assembly of microparticles in a specific region after subcutaneous injection. For further in vivo applications, the biodegradation behavior of mesoporous silica microparticles must be studied and known. Until now, most biodegradation studies have focused on mesoporous silica nanoparticles (MSNs); here, we report the biodegradation of hexagonally ordered mesoporous silica, SBA-15, with micrometer-sized lengths (∼32 μm with a high aspect ratio). The degradation of SBA-15 microparticles was investigated in simulated body fluid (SBF) and in mice by analyzing the structural change over time. SBA-15 microparticles were found to degrade in SBF and in vivo. The erosion of SBA-15 under biological conditions led to a loss of the hysteresis loop in the nitrogen adsorption/desorption isotherm and fingerprint peaks in small-angle X-ray scattering, specifically indicating a degradation of ordered mesoporous structure. Via comparison to previous results of degradation of MSNs in SBF, SBA-15 microparticles degraded faster than MCM-41 nanoparticles presumably because SBA-15 microparticles have a pore size (∼8 nm) and a pore volume larger than those of MCM-41 mesoporous silica. The surface functional groups, the residual amounts of organic templates, and the hydrothermal treatment during the synthesis could affect the rate of degradation of SBA-15. In in vivo testing, previous studies focused on the evaluation of toxicity of mesoporous silica particles in various organs. In contrast, we studied the change in the physical properties of SBA-15 microparticles depending on the duration after subcutaneous injection. The pristine SBA-15 microparticles injected

  2. Simple Microfluidic Approach to Fabricate Monodisperse Hollow Microparticles for Multidrug Delivery.

    PubMed

    Vasiliauskas, Remigijus; Liu, Dongfei; Cito, Salvatore; Zhang, Hongbo; Shahbazi, Mohammad-Ali; Sikanen, Tiina; Mazutis, Linas; Santos, Hélder A

    2015-07-15

    Herein, we report the production of monodisperse hollow microparticles from three different polymers, namely, pH-responsive acetylated dextran and hypromellose acetate succinate and biodegradable poly(lactic-co-glycolic acid), at varying polymer concentrations using a poly(dimethylsiloxane)-based microfluidic device. Hollow microparticles formed during solvent diffusion into the continuous phase when the polymer close to the interface solidified, forming the shell. In the inner part of the particle, phase separation induced solvent droplet formation, which dissolved the shell, forming a hole and a hollow-core particle. Computational simulations showed that, despite the presence of convective recirculation around the droplet, the mass-transfer rate of the solvent dissolution from the droplet to the surrounding phase was dominated by diffusion. To illustrate the potential use of hollow microparticles, we simultaneously encapsulated two anticancer drugs and investigated their loading and release profiles. In addition, by utilizing different polymer shells and polymer concentrations, the release profiles of the model drugs could be tailored according to specific demands and applications. The high encapsulation efficiency, controlled drug release, unique hollow microparticle structure, small particle size (<7 μm), and flexibility of the polymer choice could make these microparticles advanced platforms for pulmonary drug delivery.

  3. Selective microrobot control using a thermally responsive microclamper for microparticle manipulation

    NASA Astrophysics Data System (ADS)

    Go, Gwangjun; Choi, Hyunchul; Jeong, Semi; Ko, Seong Young; Park, Jong-Oh; Park, Sukho

    2016-03-01

    Microparticle manipulation using a microrobot in an enclosed environment, such as a lab-on-a-chip, has been actively studied because an electromagnetic actuated microrobot can have accurate motility and wireless controllability. In most studies on electromagnetic actuated microrobots, only a single microrobot has been used to manipulate cells or microparticles. However, the use of a single microrobot can pose several limitations when performing multiple roles in microparticle manipulation. To overcome the limitations associated with using a single microrobot, we propose a new method for the control of multiple microrobots. Multiple microrobots can be controlled independently by an electromagnetic actuation system and multiple microclampers combined with microheaters. To select a specific microrobot among multiple microrobots, we propose a microclamper composed of a clamper structure using thermally responsive hydrogel and a microheater for controlling the microclamper. A fundamental test of the proposed microparticle manipulation system is performed by selecting a specific microrobot among multiple microrobots. Through the independent locomotion of multiple microrobots with U- and V-shaped tips, heterogeneous microparticle manipulation is demonstrated in the creation of a two-dimensional structure. In the future, our proposed multiple-microrobot system can be applied to tasks that are difficult to perform using a single microrobot, such as cell manipulation, cargo delivery, tissue assembly, and cloning.

  4. Aceclofenac-loaded chitosan-tamarind seed polysaccharide interpenetrating polymeric network microparticles.

    PubMed

    Jana, Sougata; Saha, Abhimunya; Nayak, Amit Kumar; Sen, Kalyan Kumar; Basu, Sanat Kumar

    2013-05-01

    The present work deals with the preparation, characterization and evaluation of glutaraldehyde cross-linked chitosan-tamarind seed polysaccharide (TSP) interpenetrating polymeric network (IPN) microparticles for prolonged aceclofenac release. The drug entrapment efficiency of these microparticles was found 85.84±1.75 to 91.97±1.30% and their average particle sizes were ranged from 490.55±23.24 to 621.60±53.57 μm. These chitosan-TSP IPN microparticles were characterized by FTIR, DSC, and SEM analyses. The in vitro drug release from these aceclofenac-loaded chitosan-TSP IPN microparticles showed sustained release of aceclofenac over 8h and followed the Korsmeyer-Peppas model (R(2)=0.9809-0.9828) with anomalous (non-Fickian) diffusion drug release mechanism. The in vivo studies exhibited sustained anti-inflammatory activity in carrageenan-induced rats over prolonged period after oral administration of these newly developed aceclofenac-loaded IPN microparticles.

  5. The use of gelatin microparticles to delay the release of readily water-soluble materials.

    PubMed

    Lou, Y; Groves, M J

    1995-02-01

    The adsorption of D-arabinose onto gelatin microparticles demonstrated a Langmuirian adsorption pattern. Evaluation of the dissolution behaviour of D-arabinose-loaded gelatin microparticles suggested that the saccharide, loaded at a level below the adsorption saturation level, was released uniformly over a 14-h period after the loaded gelatin microparticles had been lyophilized for a second time. When dissolution curves were corrected for the initial burst effect seen after the gelatin microparticles had been loaded at higher levels of D-arabinose and lyophilized, steady-state release rates were also evident over prolonged periods. In addition, it was evident that the D-arabinose was adsorbed onto internal surfaces of the hydrated gelatin matrix. Calculation of this internal surface demonstrated the influence of the concentration of the glutaraldehyde used as a cross-linking agent and this parameter, in turn, influenced both the adsorption maxima and the subsequent equilibrium release rates. Application of this data base to a highly water-soluble complex polysaccharide antineoplastic agent, which has a higher molecular weight (22.4 kDa vs 150 Da), demonstrated similar behaviour in that a near zero-order release pattern over at least 16 h could be obtained by attention to the conditions under which the gelatin microparticles were made and subsequently loaded before lyophilization.

  6. Mucoadhesive Buccal Tablets Based on Chitosan/Gelatin Microparticles for Delivery of Propranolol Hydrochloride.

    PubMed

    Abruzzo, Angela; Cerchiara, Teresa; Bigucci, Federica; Gallucci, Maria Caterina; Luppi, Barbara

    2015-12-01

    Propranolol administration through buccal route offers some distinct advantages thanks to the easy access to the oral mucosa, fast onset of action, and avoidance of hepatic and intestinal degradation mechanisms. To overcome the effective removal existing in the buccal cavity, mucoadhesive delivery systems are considered a promising approach as they facilitate a close contact with the buccal mucosa. The aim of this study was to prepare mucoadhesive tablets based on chitosan/gelatin microparticles for buccal delivery of propranolol hydrochloride. Spray-dried microparticles were prepared with different chitosan-gelatin weight ratios and characterized in terms of yield and morphology. Microparticles were subsequently compressed with the drug to obtain loaded buccal tablets. In vitro water uptake, mucoadhesion, release, and permeation tests were performed to investigate tablet ability to hydrate, to adhere to the mucosa, and to deliver drug through buccal mucosa. Microparticles showed a different morphology based on the different chitosan-gelatin weight ratios. Moreover, buccal tablets based on the prepared microparticles showed different technological and functional characteristics in virtue of their composition. In particular, tablets with an excess of chitosan showed the best mucoadhesive properties, allowed the permeation of the greatest drug amount among all formulations, and could be promising for buccal administration of propranolol hydrochloride.

  7. Microparticle entrapment for drug release from porous-surfaced bone implants.

    PubMed

    Wang, Dongwei; Liu, Qing; Xiao, Dongqin; Guo, Tailin; Ma, Yunqing; Duan, Ke; Wang, Jianxin; Lu, Xiong; Feng, Bo; Weng, Jie

    2015-01-01

    Metallic bone implants face interfacial concerns, such as infection and insufficient bone formation. Combination of drug-loaded microparticles with the implant surface is a promising approach to reducing the concerns. The present study reports a simple method for this purpose. Drug-loaded chitosan and alginate microparticles were separately prepared by emulsion methods. Dry microparticles were introduced into porous titanium (Ti) coatings on Ti discs, and induced to agglomerate in pores by wetting with water. Agglomerates were stably entrapped in the pores: 77-82% retained in the coating after immersion in a water bath for 7 d. Discs carrying drug-loaded microparticles showed a rapid release within 6 h and a subsequent slow release up to 1 d. After coculture with Staphylococcus epidermidis for 24 h, the discs formed inhibition zones, confirming antibacterial properties. These suggest that the microparticle entrapment-based method is a promising method for reducing some of the bone-implant interfacial concerns.

  8. Use of carbon micro-particles for improved infrared temperature measurement of CMOS MEMS devices

    NASA Astrophysics Data System (ADS)

    Hopper, Richard H.; Haneef, Ibraheem; Zeeshan Ali, Syed; Udrea, Florin; Oxley, Christopher H.

    2010-04-01

    We report a technique which can be used to improve the accuracy of infrared (IR) surface temperature measurements made on micro-electro-mechanical systems (MEMS). In this work, a silicon-on-insulator (SOI) complementary metal oxide semiconductor (CMOS) MEMS thermal flow sensor was studied. The device consists of a meander-shaped resistive heater element that was fabricated using CMOS aluminum metallization and embedded in an SOI silicon oxide (SiO2) membrane. Conventional IR temperature measurements, made on the active device, were shown to give significant surface temperature errors—a consequence of the optical transparency of the SiO2 membrane and low emissivity of the metalized areas. Radiative carbon micro-particles were used to improve the measurement accuracy. By making IR measurements on carbon micro-particles placed in isothermal contact with parts of the MEMS sensor's structure, the accuracy of the surface temperature determination was significantly improved. The peak device operating temperatures measured using the 'IR micro-particle' technique were found to be in good agreement with those obtained from thermoelectric characterization. The work shows how wide area surface temperature profiles can be quickly built up by imaging multiple micro-particles using an IR charge-coupled device (CCD) detector array. The IR micro-particle technique removes the problems associated with coating MEMS sensors with a uniform high emissivity layer, which may cause damage to such devices and/or affect their thermal performance due to additional heat spreading.

  9. Controlled release of verapamil hydrochloride from waxy microparticles prepared by spray congealing.

    PubMed

    Passerini, Nadia; Perissutti, Beatrice; Albertini, Beatrice; Voinovich, Dario; Moneghini, Mariarosa; Rodriguez, Lorenzo

    2003-03-01

    In this work, the potential of waxes for preparing with the ultrasonic spray congealing technique microparticles for controlling the in vitro release of verapamil HCl was investigated. The first part of the study encompassed the optimisation of the formulation to achieve an efficient drug incorporation together with a satisfactory in vitro drug release rate. In particular, microcrystalline wax, stearyl alcohol and mixtures of the two were used. Also a surfactant (soya lecithin) was added to the formulations. After the particle size analysis, the characterisation of the microparticles involved the study of the solid state of drug and carriers in the systems (DSC, HSM and XRD) and the morphological and chemical analyses of the microparticle surface (SEM and XPS). Finally, the drug release mechanism from these devices was evaluated using the statistical moment analysis. The results of this study show that by selecting the type and the amount of the carriers, microparticles with a spherical shape and a good encapsulation efficiency were observed. These particles showed a zero-order release for 8 h, without modifying the solid state properties of the drug. Therefore, waxy microparticles prepared by the ultrasonic spray congealing technique are promising solvent-free devices for controlling the release of verapamil HCl.

  10. Reversible Switching of Liquid Crystalline Order Permits Synthesis of Homogeneous Populations of Dipolar Patchy Microparticles

    PubMed Central

    Wang, Xiaoguang; Miller, Daniel S.; de Pablo, Juan J.

    2014-01-01

    The spontaneous positioning of colloids on the surfaces of micrometer-sized liquid crystalline droplets and their subsequent polymerization offers the basis of a general and facile method for the synthesis of patchy microparticles. The existence of multiple local energetic minima, however, can generate kinetic traps for colloids on the surfaces of the liquid crystal (LC) droplets and result in heterogeneous populations of patchy microparticles. To address this issue, here we demonstrate that adsorbate-driven switching of the internal configurations of LC droplets can be used to sweep colloids to a single location on the LC droplet surfaces, thus resulting in the synthesis of homogeneous populations of patchy microparticles. The surface-driven switching of the LC can be triggered by addition of surfactant or salts, and permits the synthesis of dipolar microparticles as well as “Janus-like” microparticles. By using magnetic colloids, we illustrate the utility of the approach by synthesizing magnetically-responsive patchy microdroplets of LC with either dipolar or quadrupolar symmetry that exhibit distinct optical responses upon application of an external magnetic field. PMID:25484850

  11. Simple Microfluidic Approach to Fabricate Monodisperse Hollow Microparticles for Multidrug Delivery.

    PubMed

    Vasiliauskas, Remigijus; Liu, Dongfei; Cito, Salvatore; Zhang, Hongbo; Shahbazi, Mohammad-Ali; Sikanen, Tiina; Mazutis, Linas; Santos, Hélder A

    2015-07-15

    Herein, we report the production of monodisperse hollow microparticles from three different polymers, namely, pH-responsive acetylated dextran and hypromellose acetate succinate and biodegradable poly(lactic-co-glycolic acid), at varying polymer concentrations using a poly(dimethylsiloxane)-based microfluidic device. Hollow microparticles formed during solvent diffusion into the continuous phase when the polymer close to the interface solidified, forming the shell. In the inner part of the particle, phase separation induced solvent droplet formation, which dissolved the shell, forming a hole and a hollow-core particle. Computational simulations showed that, despite the presence of convective recirculation around the droplet, the mass-transfer rate of the solvent dissolution from the droplet to the surrounding phase was dominated by diffusion. To illustrate the potential use of hollow microparticles, we simultaneously encapsulated two anticancer drugs and investigated their loading and release profiles. In addition, by utilizing different polymer shells and polymer concentrations, the release profiles of the model drugs could be tailored according to specific demands and applications. The high encapsulation efficiency, controlled drug release, unique hollow microparticle structure, small particle size (<7 μm), and flexibility of the polymer choice could make these microparticles advanced platforms for pulmonary drug delivery. PMID:26098382

  12. Multiple unit gastroretentive drug delivery systems: a new preparation method for low density microparticles.

    PubMed

    Streubel, A; Siepmann, J; Bodmeier, R

    2003-01-01

    The aim of this study was to develop a new preparation method for low density foam-based, floating microparticles and to demonstrate the systems' performance in vitro. Major advantages of the novel preparation technique include: (i) short processing times, (ii) no exposure of the ingredients to high temperatures, (iii) the possibility to avoid toxic organic solvents, and (iv) high encapsulation efficiencies close to 100%. Floating microparticles consisting of polypropylene foam powder, model drug [chlorpheniramine maleate (CPM), diltiazem HCl, theophylline or verapamil HCl] and polymer [Eudragit RS or polymethyl methacrylate (PMMA)] were prepared by soaking the microporous foam carrier with an organic solution of drug and polymer and subsequent drying. The effects of various formulation and processing parameters on the resulting in vitro floating behaviour, internal and external particle morphology, drug loading, in vitro drug release and physical state of the incorporated drug were studied. Good in vitro floating behaviour was observed in most cases and a broad variety of drug release patterns could be achieved by varying the drug loading and type of polymer. Interestingly, PMMA-based microparticles showed incomplete drug release with verapamil HCl. This restriction could be overcome by forming the free base of the drug prior to microparticle preparation. In contrast to the salt, the free base acted as a plasticizer for PMMA, resulting in sufficiently high diffusion coefficients and, consequently, complete drug release. The low density microparticles were compressed into rapidly disintegrating tablets in order to provide an administrable oral dosage form.

  13. CLEC-2 expression is maintained on activated platelets and on platelet microparticles.

    PubMed

    Gitz, Eelo; Pollitt, Alice Y; Gitz-Francois, Jerney J; Alshehri, Osama; Mori, Jun; Montague, Samantha; Nash, Gerard B; Douglas, Michael R; Gardiner, Elizabeth E; Andrews, Robert K; Buckley, Christopher D; Harrison, Paul; Watson, Steve P

    2014-10-01

    The C-type lectin-like receptor CLEC-2 mediates platelet activation through a hem-immunoreceptor tyrosine-based activation motif (hemITAM). CLEC-2 initiates a Src- and Syk-dependent signaling cascade that is closely related to that of the 2 platelet ITAM receptors: glycoprotein (GP)VI and FcγRIIa. Activation of either of the ITAM receptors induces shedding of GPVI and proteolysis of the ITAM domain in FcγRIIa. In the present study, we generated monoclonal antibodies against human CLEC-2 and used these to measure CLEC-2 expression on resting and stimulated platelets and on other hematopoietic cells. We show that CLEC-2 is restricted to platelets with an average copy number of ∼2000 per cell and that activation of CLEC-2 induces proteolytic cleavage of GPVI and FcγRIIa but not of itself. We further show that CLEC-2 and GPVI are expressed on CD41+ microparticles in megakaryocyte cultures and in platelet-rich plasma, which are predominantly derived from megakaryocytes in healthy donors, whereas microparticles derived from activated platelets only express CLEC-2. Patients with rheumatoid arthritis, an inflammatory disease associated with increased microparticle production, had raised plasma levels of microparticles that expressed CLEC-2 but not GPVI. Thus, CLEC-2, unlike platelet ITAM receptors, is not regulated by proteolysis and can be used to monitor platelet-derived microparticles.

  14. Aceclofenac-loaded chitosan-tamarind seed polysaccharide interpenetrating polymeric network microparticles.

    PubMed

    Jana, Sougata; Saha, Abhimunya; Nayak, Amit Kumar; Sen, Kalyan Kumar; Basu, Sanat Kumar

    2013-05-01

    The present work deals with the preparation, characterization and evaluation of glutaraldehyde cross-linked chitosan-tamarind seed polysaccharide (TSP) interpenetrating polymeric network (IPN) microparticles for prolonged aceclofenac release. The drug entrapment efficiency of these microparticles was found 85.84±1.75 to 91.97±1.30% and their average particle sizes were ranged from 490.55±23.24 to 621.60±53.57 μm. These chitosan-TSP IPN microparticles were characterized by FTIR, DSC, and SEM analyses. The in vitro drug release from these aceclofenac-loaded chitosan-TSP IPN microparticles showed sustained release of aceclofenac over 8h and followed the Korsmeyer-Peppas model (R(2)=0.9809-0.9828) with anomalous (non-Fickian) diffusion drug release mechanism. The in vivo studies exhibited sustained anti-inflammatory activity in carrageenan-induced rats over prolonged period after oral administration of these newly developed aceclofenac-loaded IPN microparticles. PMID:23399430

  15. Microparticle entrapment for drug release from porous-surfaced bone implants.

    PubMed

    Wang, Dongwei; Liu, Qing; Xiao, Dongqin; Guo, Tailin; Ma, Yunqing; Duan, Ke; Wang, Jianxin; Lu, Xiong; Feng, Bo; Weng, Jie

    2015-01-01

    Metallic bone implants face interfacial concerns, such as infection and insufficient bone formation. Combination of drug-loaded microparticles with the implant surface is a promising approach to reducing the concerns. The present study reports a simple method for this purpose. Drug-loaded chitosan and alginate microparticles were separately prepared by emulsion methods. Dry microparticles were introduced into porous titanium (Ti) coatings on Ti discs, and induced to agglomerate in pores by wetting with water. Agglomerates were stably entrapped in the pores: 77-82% retained in the coating after immersion in a water bath for 7 d. Discs carrying drug-loaded microparticles showed a rapid release within 6 h and a subsequent slow release up to 1 d. After coculture with Staphylococcus epidermidis for 24 h, the discs formed inhibition zones, confirming antibacterial properties. These suggest that the microparticle entrapment-based method is a promising method for reducing some of the bone-implant interfacial concerns. PMID:26057256

  16. Meeting Review: Airborne Aerosol Inlet Workshop

    NASA Technical Reports Server (NTRS)

    Baumgardner, Darrel; Huebert, Barry; Wilson, Chuck

    1991-01-01

    Proceedings from the Airborne Aerosol Inlet Workshop are presented. The two central topics of discussion were the role of aerosols in atmospheric processes and the difficulties in characterizing aerosols. The following topics were discussed during the working sessions: airborne observations to date; identification of inlet design issues; inlet modeling needs and directions; objectives for aircraft experiments; and future laboratory and wind tunnel studies.

  17. Airborne Relay-Based Regional Positioning System

    PubMed Central

    Lee, Kyuman; Noh, Hongjun; Lim, Jaesung

    2015-01-01

    Ground-based pseudolite systems have some limitations, such as low vertical accuracy, multipath effects and near-far problems. These problems are not significant in airborne-based pseudolite systems. However, the monitoring of pseudolite positions is required because of the mobility of the platforms on which the pseudolites are mounted, and this causes performance degradation. To address these pseudolite system limitations, we propose an airborne relay-based regional positioning system that consists of a master station, reference stations, airborne relays and a user. In the proposed system, navigation signals are generated from the reference stations located on the ground and are relayed via the airborne relays. Unlike in conventional airborne-based systems, the user in the proposed system sequentially estimates both the locations of airborne relays and his/her own position. Therefore, a delay due to monitoring does not occur, and the accuracy is not affected by the movement of airborne relays. We conducted several simulations to evaluate the performance of the proposed system. Based on the simulation results, we demonstrated that the proposed system guarantees a higher accuracy than airborne-based pseudolite systems, and it is feasible despite the existence of clock offsets among reference stations. PMID:26029953

  18. Airborne Oceanographic Lidar (AOL) (Global Carbon Cycle)

    NASA Technical Reports Server (NTRS)

    2003-01-01

    This bimonthly contractor progress report covers the operation, maintenance and data management of the Airborne Oceanographic Lidar and the Airborne Topographic Mapper. Monthly activities included: mission planning, sensor operation and calibration, data processing, data analysis, network development and maintenance and instrument maintenance engineering and fabrication.

  19. Global Test Range: Toward Airborne Sensor Webs

    NASA Technical Reports Server (NTRS)

    Mace, Thomas H.; Freudinger, Larry; DelFrate John H.

    2008-01-01

    This viewgraph presentation reviews the planned global sensor network that will monitor the Earth's climate, and resources using airborne sensor systems. The vision is an intelligent, affordable Earth Observation System. Global Test Range is a lab developing trustworthy services for airborne instruments - a specialized Internet Service Provider. There is discussion of several current and planned missions.

  20. A Simple Method for Collecting Airborne Pollen

    ERIC Educational Resources Information Center

    Kevan, Peter G.; DiGiovanni, Franco; Ho, Rong H.; Taki, Hisatomo; Ferguson, Kristyn A.; Pawlowski, Agata K.

    2006-01-01

    Pollination is a broad area of study within biology. For many plants, pollen carried by wind is required for successful seed set. Airborne pollen also affects human health. To foster studies of airborne pollen, we introduce a simple device--the "megastigma"--for collecting pollen from the air. This device is flexible, yielding easily obtained data…

  1. The Continuous wavelet in airborne gravimetry

    NASA Astrophysics Data System (ADS)

    Liang, X.; Liu, L.

    2013-12-01

    Airborne gravimetry is an efficient method to recover medium and high frequency band of earth gravity over any region, especially inaccessible areas, which can measure gravity data with high accuracy,high resolution and broad range in a rapidly and economical way, and It will play an important role for geoid and geophysical exploration. Filtering methods for reducing high-frequency errors is critical to the success of airborne gravimetry due to Aircraft acceleration determination based on GPS.Tradiontal filters used in airborne gravimetry are FIR,IIR filer and so on. This study recommends an improved continuous wavelet to process airborne gravity data. Here we focus on how to construct the continuous wavelet filters and show their working principle. Particularly the technical parameters (window width parameter and scale parameter) of the filters are tested. Then the raw airborne gravity data from the first Chinese airborne gravimetry campaign are filtered using FIR-low pass filter and continuous wavelet filters to remove the noise. The comparison to reference data is performed to determinate external accuracy, which shows that continuous wavelet filters applied to airborne gravity in this thesis have good performances. The advantages of the continuous wavelet filters over digital filters are also introduced. The effectiveness of the continuous wavelet filters for airborne gravimetry is demonstrated through real data computation.

  2. Airborne Visible Laser Optical Communications Program (AVLOC)

    NASA Technical Reports Server (NTRS)

    Ward, J. H.

    1975-01-01

    The design, development, and operation of airborne and ground-based laser communications and laser radar hardware is described in support of the Airborne Visible Laser Optical Communication program. The major emphasis is placed on the development of a highly flexible test bed for the evaluation of laser communications systems techniques and components in an operational environment.

  3. Directed Assembly of Hierarchically Ordered Clusters from Anisotropic Microparticles

    NASA Astrophysics Data System (ADS)

    Han, Koohee; Bharti, Bhuvnesh; Shields, C. Wyatt, IV; Lopez, Gabriel P.; Velev, Orlin D.

    The directed assembly of colloidal particles with specific connectivity, symmetry, and directional response requires controlled interactions and means of programmable binding force. We will show how patchy microparticles can be hierarchically assembled into ordered clusters, resulting from directional interactions between metal-coated facets. First, we introduce lipid mediated capillary bridging as a new class of binding force for directed assembly of metallo-dielectric patchy microspheres. Iron oxide surface patches on latex microspheres were selectively wetted with liquid lipids, guiding the particle assembly into well-defined 2D and 3D clusters. The temperature driven fluid-to-gel phase transition of the fatty acids acts as a thermal switch for cluster assembly and disassembly. Secondly, we used external fields to bind patchy microcubes based on their polarization configuration and interparticle interaction. We present assembled clusters of cobalt-coated patchy microcubes that can be dynamically reconfigured using external magnetic field. The residual polarization of ferromagnetic cobalt patches allows for preserving the assembled sequence even in the absence of the field and drives dynamic reconfiguration of assembled clusters. NSF Grant #DMR-1121107.

  4. On-chip microfluidic biosensor using superparamagnetic microparticles

    PubMed Central

    Kokkinis, G.; Keplinger, F.; Giouroudi, I.

    2013-01-01

    In this paper, an integrated solution towards an on-chip microfluidic biosensor using the magnetically induced motion of functionalized superparamagnetic microparticles (SMPs) is presented. The concept of the proposed method is that the induced velocity on SMPs in suspension, while imposed to a magnetic field gradient, is inversely proportional to their volume. Specifically, a velocity variation of suspended functionalized SMPs inside a detection microchannel with respect to a reference velocity, specified in a parallel reference microchannel, indicates an increase in their non-magnetic volume. This volumetric increase of the SMPs is caused by the binding of organic compounds (e.g., biomolecules) to their functionalized surface. The new compounds with the increased non-magnetic volume are called loaded SMPs (LSMPs). The magnetic force required for the manipulation of the SMPs and LSMPs is produced by current currying conducting microstructures, driven by a programmable microcontroller. Experiments were carried out as a proof of concept. A promising decrease in the velocity of the LSMPs in comparison to that of the SMPs was measured. Thus, it is the velocity variation which determines the presence of the organic compounds in the sample fluid. PMID:24396528

  5. Procoagulant behavior and platelet microparticle generation on nanoporous alumina.

    PubMed

    Ferraz, Natalia; Hong, Jaan; Karlsson Ott, Marjam

    2010-05-01

    In the present work, we have investigated platelet microparticle (PMP) generation in whole blood after contact with nanoporous alumina. Alumina membranes with pore sizes of 20 and 200 nm in diameter were incubated with whole blood and the number of PMP in the fluid phase was determined by flow cytometry. The role of the complement system in PMP generation was investigated using an analog of the potent complement inhibitor compstatin. Moreover, the procoagulant activity of the two pore size membranes were compared by measuring thrombin formation. Results indicated that PMP were not present in the fluid phase after whole blood contact with either of the alumina membranes. However, scanning electron microscope micrographs clearly showed the presence of PMP clusters on the 200 nm pore size alumina, while PMP were practically absent on the 20 nm membrane. We probed no influence of complement activation in PMP generation and adhesion and we hypothesize that other specific material-related protein-platelet interactions are taking place. A clear difference in procoagulant activity between the membranes could also be seen, 20 nm alumina showed 100% higher procoagulant activity than 200 nm membrane. By combining surface evaluation and flow cytometry analyses of the fluid phase, we are able to conclude that 200 nm pore size alumina promotes PMP generation and adhesion while the 20 nm membrane does not appreciably cause any release or adhesion of PMP, thus indicating a direct connection between PMP generation and nanoporosity.

  6. Proteomic characterization of human platelet-derived microparticles.

    PubMed

    Capriotti, Anna Laura; Caruso, Giuseppe; Cavaliere, Chiara; Piovesana, Susy; Samperi, Roberto; Laganà, Aldo

    2013-05-01

    Microparticles (MPs) are small fragments of apoptotic or activated cells that may contribute to pathological processes in many diseases. Platelet-derived MPs (PMPs) are the most abundant type of MPs in human blood. To characterize the proteins in PMPs we used a shotgun proteomics approach by nanoHPLC separation followed by MS analysis on an LTQ Orbitrap XL. PMPs were produced from isolated platelets stimulated with adenosine diphosphate (ADP). We developed an analytical platform constituted by two different steps: in the first one we used a standard shotgun strategy; in the second one, to improve low-molecular weight, low-abundance-proteins identification, the samples were fractionated using hydrogel nanoparticles, an enrichment system based on a mixed mechanism of dimensional exclusion and colorant affinity. This was chosen to tackle a common issue with shotgun approaches, in which the low-abundance proteins are not detected when surveys are on a broad scale. By means of the entire analytical platform, we identified 603 proteins, 243 of which were not previously identified. A simple and straightforward procedure for the study of PMPs was provided, producing a tool for further understanding their biological and pathological roles, and a baseline for future studies aimed at discovering biomarkers involved in several diseases.

  7. Polymorphic control of inhalation microparticles prepared by crystallization.

    PubMed

    Murnane, Darragh; Marriott, Christopher; Martin, Gary P

    2008-09-01

    Milling processes are known to cause polymorphic transition in enantiotropic systems and the micronization process employed to produce microparticles for inhalation formulations has been reported to result in solid-state damage. The aim of the current work was to investigate the polymorphism of salmeterol xinafoate (SX) following antisolvent micronization from poly(ethylene glycol) (PEG) solvents and compare this to the properties of SX conventionally crystallized and micronized. Powder X-ray diffraction revealed that SX crystallized predominantly as the SX form I polymorph following rapid precipitation from PEG solvents and cooling crystallization from propan-2-ol. Thermo-kinetic analysis using a modified Avrami-Erofe'ev equation was applied to differential scanning calorimetric thermographs of crystallized and micronized SX. The kinetic analysis revealed that SX crystallized from PEG solvents underwent significantly less or no re-crystallization of SX form II from the melt. A polymorphic transition was identified upon heating ball-milled SX, although the untreated material was resistant to such transformation. The thermal behaviour of SX crystallized from PEG solvents was consistent with a lower degree of crystal lattice disorder and higher enantiotropic purity than SX crystallized from propan-2-ol; the same was also true when comparing SX before and after micronization.

  8. Lectin-Based Characterization of Vascular Cell Microparticle Glycocalyx

    PubMed Central

    Scruggs, April K.; Cioffi, Eugene A.; Cioffi, Donna L.; King, Judy A. C.; Bauer, Natalie N.

    2015-01-01

    Microparticles (MPs) are released constitutively and from activated cells. MPs play significant roles in vascular homeostasis, injury, and as biomarkers. The unique glycocalyx on the membrane of cells has frequently been exploited to identify specific cell types, however the glycocalyx of the MPs has yet to be defined. Thus, we sought to determine whether MPs, released both constitutively and during injury, from vascular cells have a glycocalyx matching those of the parental cell type to provide information on MP origin. For these studies we used rat pulmonary microvascular and artery endothelium, pulmonary smooth muscle, and aortic endothelial cells. MPs were collected from healthy or cigarette smoke injured cells and analyzed with a panel of lectins for specific glycocalyx linkages. Intriguingly, we determined that the MPs released either constitutively or stimulated by CSE injury did not express the same glycocalyx of the parent cells. Further, the glycocalyx was not unique to any of the specific cell types studied. These data suggest that MPs from both normal and healthy vascular cells do not share the parental cell glycocalyx makeup. PMID:26274589

  9. Multiresponsive hydrogel photonic crystal microparticles with inverse-opal structure.

    PubMed

    Wang, Jianying; Hu, Yuandu; Deng, Renhua; Liang, Ruijing; Li, Weikun; Liu, Shanqin; Zhu, Jintao

    2013-07-16

    Hydrogel photonic crystal microparticles (HPCMs) with inverse-opal structure are generated through a combination of microfluidic and templating technique. Temperature and pH responsive HPCMs have firstly been prepared by copolymerizing functional monomers, for example, N-isopropylacrylamide (NIPAm) and methacrylic acid (MAA). HPCMs not only show tunable color variation almost covering the entire wavelength of visible light (above 150 nm of stop-band shift) by simply tailoring temperature or pH value of the solution, but also display rapid response (less than 1 min) due to the small volume and well-ordered porous structure. Importantly, the temperature sensing window of the HPCMs can be enlarged by controlling the transition temperature of the hydrogel matrix, and the HPCMs also exhibit good reversibility and reproducibility for pH response. Moreover, functional species or particles (such as azobenzene derivative or magnetic nanoparticles) can be further introduced into the hydrogel matrix by using post-treatment process. These functionalized HPCMs can respond to the UV/visible light without significantly influencing the temperature and pH response, and thus, multiresponsive capability within one single particle can be realized. The presence of magnetic nanoparticles may facilitate secondary assembly, which has potential applications in advanced optical devices. PMID:23768084

  10. Solid lipid microparticles for enhanced dermal delivery of tetracycline HCl.

    PubMed

    Rahimpour, Yahya; Javadzadeh, Yousef; Hamishehkar, Hamed

    2016-09-01

    Acne vulgaris (commonly called acne) is a most common skin disease during adolescence, afflicting more than 85% of teenagers. Topical tetracycline (Tc) is used for mild inflammatory acne and as an adjunct to systemic treatment in more severe forms. Solid lipid microparticles (SLMs) are useful tool for topical delivery because of their biodegradable, biocompatible and low toxic characteristic accompanying with excellent skin hydration, occlusiveness and controlled release properties. The purpose of this study was to prepare Tc-loaded SLMs were produced by the spray drying technique and characterized by scanning electron microscopy, powder X-ray diffractometry and differential scanning calorimetry. In vitro and ex vivo release characteristics of Tc through SLMs and control formulations (aqueous carbopol gel) were evaluated over 24h using a vertical Franz diffusion cell through cellulose acetate membranes and exercised rat skin, respectively. SLM formulations present high encapsulation values above 97% without significant different among formulations (p<0.05). The sustained release pattern of Tc through SLMs was illustrated by in vitro release study. The ex vivo drug skin permeation study revealed that Tc dermal deposition of optimum SLMs formulation was about 7 times that of the control formulations. The enhanced skin penetration and accumulation of Tc observed for Tc-loaded SLMs may increase the efficiency of acne therapy and decrease the associated Tc side effects. PMID:27131093

  11. Trapping colloidal dielectric microparticles with overlapping evanescent optical waves

    NASA Astrophysics Data System (ADS)

    Khakimov, R.; Shevchenko, A.; Havukainen, A.; Lindfors, K.; Kaivola, M.

    2012-10-01

    We experimentally demonstrate the creation of a stable surface trap for colloidal microparticles in a high-intensity evanescent optical field that is produced by total internal reflection of two counter-propagating and mutually incoherent laser beams. While the particles confined in the trap undergo fast Brownian motion, they never "stick" to the surface - not even at high optical powers - but rather levitate above the surface. If many particles are stored in the trap, they tend to form a well ordered self-organized array. We apply a numerical model based on the general energy-momentum tensor formalism to evaluate the overall optical force acting on a trapped particle. The optical-field parameters are calculated using the finite element method. The simulations show that for small particles a sharp repulsive potential at the surface - required for the levitation - can have neither optical nor light-induced thermal origin. Among the possible non-optical forces, electrostatic double-layer repulsion is often considered to be the origin of the levitation. We find, however, that the experimentally observed levitation of small particles in a high-intensity evanescent-wave trap cannot be explained by this effect.

  12. Dynamic adhesion forces between microparticles and substrates in water.

    PubMed

    Xu, Quan; Li, Mingtao; Zhang, Lipeng; Niu, Jianbing; Xia, Zhenhai

    2014-09-23

    The interactions between micrometer-sized particles and substrates in aqueous environment are fundamental to numerous natural phenomena and industrial processes. Here we report a dynamically induced enhancement in adhesion interactions between microparticles and substrates immerged in water, air, and hexane. The dynamic adhesion force was measured by pulling microsized spheres off various substrate (hydrophilic/hydrophobic) surfaces at different retracting velocities. It was observed that when the pull-off velocity varies from 0.02 to 1500 μm/s, there is 100-200% increase in adhesion force in water while it has a 100% increase in nitrogen and hexane. The dynamic adhesion enhancement reduces with increasing effective contact angle defined by the average cosine of wetting angles of the substrates and the particles, and approaches the values measured in dry nitrogen and hexane as the effective contact angle is larger than 90(o). A dynamic model was developed to predict the adhesion forces resulting from this dynamic effect, and the predictions correlate well with the experimental results. The stronger dynamic adhesion enhancement in water is mainly attributed to electrical double layers and the restructuring of water in the contact area between particles and substrates. PMID:25162139

  13. Analysis of the Particle Formation Process of Structured Microparticles.

    PubMed

    Baldelli, Alberto; Boraey, Mohammed A; Nobes, David S; Vehring, Reinhard

    2015-08-01

    The particle formation process for microparticles of cellulose acetate butyrate dried from an acetone solution was investigated experimentally and theoretically. A monodisperse droplet chain was used to produce solution microdroplets in a size range of 55-70 μm with solution concentrations of 0.37 and 10 mg/mL. As the droplets dried in a laminar air flow with a temperature of 30, 40, or 55 °C, the particle formation process was recorded by two independent optical methods. Dried particles in a size range of 10-30 μm were collected for morphology analysis, showing hollow, elongated particles whose structure was dependent on the drying gas temperature and initial solution concentration. The setup allowed comprehensive measurements of the particle formation process to be made, including the period after initial shell formation. The early particle formation process for this system was controlled by the diffusion of cellulose acetate butyrate in the liquid phase, whereas later stages of the process were dominated by shell buckling and folding. PMID:25685865

  14. Endothelial microparticles mediate inflammation-induced vascular calcification.

    PubMed

    Buendía, Paula; Montes de Oca, Addy; Madueño, Juan Antonio; Merino, Ana; Martín-Malo, Alejandro; Aljama, Pedro; Ramírez, Rafael; Rodríguez, Mariano; Carracedo, Julia

    2015-01-01

    Stimulation of endothelial cells (ECs) with TNF-α causes an increase in the expression of bone morphogenetic protein-2 (BMP-2) and the production of endothelial microparticles (EMPs). BMP-2 is known to produce osteogenic differentiation of vascular smooth muscle cells (VSMCs). It was found that EMPs from TNF-α-stimulated endothelial cells (HUVECs) contained a significant amount of BMP-2 and were able to enhance VSMC osteogenesis and calcification. Calcium content was greater in VSMCs exposed to EMPs from TNF-α-treated HUVECs than EMPs from nontreated HUVECs (3.56 ± 0.57 vs. 1.48 ± 0.56 µg/mg protein; P < 0.05). The increase in calcification was accompanied by up-regulation of Cbfa1 (osteogenic transcription factor) and down-regulation of SM22α (VSMC lineage marker). Inhibition of BMP-2 by small interfering RNA reduced the VSMC calcification induced by EMPs from TNF-α-treated HUVECs. Similar osteogenic capability was observed in EMPs from both patients with chronic kidney disease and senescent cells, which also presented a high level of BMP-2 expression. Labeling of EMPs with CellTracker shows that EMPs are phagocytized by VSMCs under all conditions (with or without high phosphate, control, and EMPs from TNF-α-treated HUVECs). Our data suggest that EC damage results in the release of EMPs with a high content of calcium and BMP-2 that are able to induce calcification and osteogenic differentiation of VSMCs.

  15. Endothelial microparticles as conveyors of information in atherosclerotic disease.

    PubMed

    Schiro, A; Wilkinson, F L; Weston, R; Smyth, J V; Serracino-Inglott, F; Alexander, M Y

    2014-06-01

    Endothelial microparticles (EMPs) are complex submicron membrane-shed vesicles released into the circulation following endothelium cell activation or apoptosis. They are classified as either physiological or pathological, with anticoagulant or pro-inflammatory effects respectively. Endothelial dysfunction caused by inflammation is a key initiating event in atherosclerotic plaque formation. Athero-emboli, resulting from ruptured carotid plaques are a major cause of stroke. Current clinical techniques for arterial assessment, angiography and carotid ultrasound, give accurate information about stenosis but limited evidence on plaque composition, inflammation or vulnerability; as a result, patients with asymptomatic, or fragile carotid lesions, may not be identified and treated effectively. There is a need to discover novel biomarkers and develop more efficient diagnostic approaches in order to stratify patients at most risk of stroke, who would benefit from interventional surgery. Increasing evidence suggests that EMPs play an important role in the pathogenesis of cardiovascular disease, acting as a marker of damage, either exacerbating disease progression or triggering a repair response. In this regard, it has been suggested that EMPs have the potential to act as biomarkers of disease status. In this review, we will present the evidence to support this hypothesis and propose a novel concept for the development of a diagnostic device that could be implemented in the clinic. PMID:24721189

  16. Porous silicon microparticles for delivery of siRNA therapeutics.

    PubMed

    Shen, Jianliang; Wu, Xiaoyan; Lee, Yeonju; Wolfram, Joy; Yang, Zhizhou; Mao, Zong-Wan; Ferrari, Mauro; Shen, Haifa

    2015-01-15

    Small interfering RNA (siRNA) can be used to suppress gene expression, thereby providing a new avenue for the treatment of various diseases. However, the successful implementation of siRNA therapy requires the use of delivery platforms that can overcome the major challenges of siRNA delivery, such as enzymatic degradation, low intracellular uptake and lysosomal entrapment. Here, a protocol for the preparation and use of a biocompatible and effective siRNA delivery system is presented. This platform consists of polyethylenimine (PEI) and arginine (Arg)-grafted porous silicon microparticles, which can be loaded with siRNA by performing a simple mixing step. The silicon particles are gradually degraded over time, thereby triggering the formation of Arg-PEI/siRNA nanoparticles. This delivery vehicle provides a means for protecting and internalizing siRNA, without causing cytotoxicity. The major steps of polycation functionalization, particle characterization, and siRNA loading are outlined in detail. In addition, the procedures for determining particle uptake, cytotoxicity, and transfection efficacy are also described.

  17. Direct thiol-ene photocoating of polyorganosiloxane microparticles.

    PubMed

    Kuttner, Christian; Maier, Petra C; Kunert, Carmen; Schlaad, Helmut; Fery, Andreas

    2013-12-31

    This work presents the modification of polyorganosiloxane microparticles by surface-initiated thiol-ene photochemistry. By this photocoating, we prepared different core/shell particles with a polymeric shell within narrow size distributions (PDI = 0.041-0.12). As core particle, we used highly monodisperse spherical polyorganosiloxane particles prepared from (3-mercaptopropyl)trimethoxysilane (MPTMS) with a radius of 0.49 μm. We utilize the high surface coverage of mercaptopropyl functions to generate surface-localized radicals upon irradiation with UVA-light without additional photoinitiator. The continuous generation of radicals was followed by a dye degradation experiment (UV/vis spectroscopy). Surface-localized radicals were used as copolymer anchoring sites ("grafting-onto" deposition of different PB-b-PS diblock copolymers) and polymerization initiators ("grafting-from" polymerization of PS). Photocoated particles were characterized for their morphology (SEM, TEM), size, and size distribution (DLS). For PS-coated particles, the polymer content (up to 24% in 24 h) was controlled by the polymerization time upon UVA exposure. The coating thickness was evaluated by thermogravimetric analysis (TGA) using a simple analytical core/shell model. Raman spectroscopy was applied to directly follow the time-dependent consumption of thiols by photoinitiation. PMID:24320891

  18. Lectin-Based Characterization of Vascular Cell Microparticle Glycocalyx.

    PubMed

    Scruggs, April K; Cioffi, Eugene A; Cioffi, Donna L; King, Judy A C; Bauer, Natalie N

    2015-01-01

    Microparticles (MPs) are released constitutively and from activated cells. MPs play significant roles in vascular homeostasis, injury, and as biomarkers. The unique glycocalyx on the membrane of cells has frequently been exploited to identify specific cell types, however the glycocalyx of the MPs has yet to be defined. Thus, we sought to determine whether MPs, released both constitutively and during injury, from vascular cells have a glycocalyx matching those of the parental cell type to provide information on MP origin. For these studies we used rat pulmonary microvascular and artery endothelium, pulmonary smooth muscle, and aortic endothelial cells. MPs were collected from healthy or cigarette smoke injured cells and analyzed with a panel of lectins for specific glycocalyx linkages. Intriguingly, we determined that the MPs released either constitutively or stimulated by CSE injury did not express the same glycocalyx of the parent cells. Further, the glycocalyx was not unique to any of the specific cell types studied. These data suggest that MPs from both normal and healthy vascular cells do not share the parental cell glycocalyx makeup.

  19. Origin and biological significance of shed-membrane microparticles.

    PubMed

    Tesse, A; Martínez, M C; Meziani, F; Hugel, B; Panaro, M A; Mitolo, V; Freyssinet, J-M; Andriantsitohaina, R

    2006-09-01

    Microparticles (MPs) are small vesicles released from the membrane surface during eukaryotic cell activation or apoptosis. They originate from various cell types, displaying the typical surface cell proteins and cytoplasmic components of their cell origin. Their procoagulant properties are linked to phosphatidylserine exposed at their surface. Numerous reports have shown that MPs are able to mediate long-range signaling, acting on different targets from those of their own cellular origin. MPs-mediated binding to other cells occurs by integration into the membrane, by adhesion to the cell surface or by ligand-receptor interaction. Elevated levels of circulating MPs have been detected in cardiovascular and immune-mediated diseases. Despite extensive studies of the procoagulant and pro-inflammatory properties of MPs, little is known about their effect on vascular function. MPs accumulate in atherosclerotic plaques and injured vascular wall. Circulating MPs from patients with myocardial infarction induce endothelial dysfunction by impairing the endothelial nitric oxide (NO) pathway, without causing changes in endothelial NO-synthase (eNOS) expression. However, MPs from T-cells may induce endothelial dysfunction, altering gene expression of eNOS and caveolin-1. Moreover, MPs may promote the expression of pro-inflammatory proteins implicated in vascular contractility alterations. This review describes the origin of MPs and their biological role in physiological conditions and in various pathological states, with special reference to the possible linkage between their pro-inflammatory and procoagulant properties and vascular dysfunction.

  20. Selective Cell Targeting with Light-Absorbing Microparticles and Nanoparticles

    PubMed Central

    Pitsillides, Costas M.; Joe, Edwin K.; Wei, Xunbin; Anderson, R. Rox; Lin, Charles P.

    2003-01-01

    We describe a new method for selective cell targeting based on the use of light-absorbing microparticles and nanoparticles that are heated by short laser pulses to create highly localized cell damage. The method is closely related to chromophore-assisted laser inactivation and photodynamic therapy, but is driven solely by light absorption, without the need for photochemical intermediates (particularly singlet oxygen). The mechanism of light-particle interaction was investigated by nanosecond time-resolved microscopy and by thermal modeling. The extent of light-induced damage was investigated by cell lethality, by cell membrane permeability, and by protein inactivation. Strong particle size dependence was found for these interactions. A technique based on light to target endogenous particles is already being exploited to treat pigmented cells in dermatology and ophthalmology. With exogenous particles, phamacokinetics and biodistribution studies are needed before the method can be evaluated against photodynamic therapy for cancer treatment. However, particles are unique, unlike photosensitizers, in that they can remain stable and inert in cells for extended periods. Thus they may be particularly useful for prelabeling cells in engineered tissue before implantation. Subsequent irradiation with laser pulses will allow control of the implanted cells (inactivation or modulation) in a noninvasive manner. PMID:12770906

  1. Leidenfrost drops and micro-particles: organization and evaporation

    NASA Astrophysics Data System (ADS)

    Maquet, Laurent; Colinet, Pierre; Dorbolo, Stéphane

    2014-11-01

    We investigate the behavior of hydrophilic microparticles dropped into Leidenfrost drops. These particles appears to go through the drop until they reach the bottom surface of the drop where they are dewetted. Due to the evaporation of the drop, the surface of the drop decreases. Thus, the particles that are trapped at the surface of the drop due to the dewetting begin to cover more and more the drop. At a point, they even cover the whole surface of the drop. The superficial density of the particles at the surface is ~0.8 and the fraction of the beads that stay trapped at the surface until the cover is complete is always larger than 0 . 7 . We measured evaporation rates and compared the case of drops with and without particles. These evaporation rates are always decreased by the presence of the particles. This is due to the dewetting. Indeed, the effective surface of evaporation is decreased by the presence of particles at the surface. Thus, knowing how the evaporation is affected by the presence of the particles, we can measure contact angles at the lower surface of these levitating drops.

  2. Microparticles: A New Perspective in Central Nervous System Disorders

    PubMed Central

    Schindler, Stephanie M.; Little, Jonathan P.

    2014-01-01

    Microparticles (MPs) are a heterogeneous population of small cell-derived vesicles, ranging in size from 0.1 to 1 μm. They contain a variety of bioactive molecules, including proteins, biolipids, and nucleic acids, which can be transferred between cells without direct cell-to-cell contact. Consequently, MPs represent a novel form of intercellular communication, which could play a role in both physiological and pathological processes. Growing evidence indicates that circulating MPs contribute to the development of cancer, inflammation, and autoimmune and cardiovascular diseases. Most cell types of the central nervous system (CNS) have also been shown to release MPs, which could be important for neurodevelopment, CNS maintenance, and pathologies. In disease, levels of certain MPs appear elevated; therefore, they may serve as biomarkers allowing for the development of new diagnostic tools for detecting the early stages of CNS pathologies. Quantification and characterization of MPs could also provide useful information for making decisions on treatment options and for monitoring success of therapies, particularly for such difficult-to-treat diseases as cerebral malaria, multiple sclerosis, and Alzheimer's disease. Overall, studies on MPs in the CNS represent a novel area of research, which promises to expand the knowledge on the mechanisms governing some of the physiological and pathophysiological processes of the CNS. PMID:24860829

  3. Endothelial microparticles mediate inflammation-induced vascular calcification.

    PubMed

    Buendía, Paula; Montes de Oca, Addy; Madueño, Juan Antonio; Merino, Ana; Martín-Malo, Alejandro; Aljama, Pedro; Ramírez, Rafael; Rodríguez, Mariano; Carracedo, Julia

    2015-01-01

    Stimulation of endothelial cells (ECs) with TNF-α causes an increase in the expression of bone morphogenetic protein-2 (BMP-2) and the production of endothelial microparticles (EMPs). BMP-2 is known to produce osteogenic differentiation of vascular smooth muscle cells (VSMCs). It was found that EMPs from TNF-α-stimulated endothelial cells (HUVECs) contained a significant amount of BMP-2 and were able to enhance VSMC osteogenesis and calcification. Calcium content was greater in VSMCs exposed to EMPs from TNF-α-treated HUVECs than EMPs from nontreated HUVECs (3.56 ± 0.57 vs. 1.48 ± 0.56 µg/mg protein; P < 0.05). The increase in calcification was accompanied by up-regulation of Cbfa1 (osteogenic transcription factor) and down-regulation of SM22α (VSMC lineage marker). Inhibition of BMP-2 by small interfering RNA reduced the VSMC calcification induced by EMPs from TNF-α-treated HUVECs. Similar osteogenic capability was observed in EMPs from both patients with chronic kidney disease and senescent cells, which also presented a high level of BMP-2 expression. Labeling of EMPs with CellTracker shows that EMPs are phagocytized by VSMCs under all conditions (with or without high phosphate, control, and EMPs from TNF-α-treated HUVECs). Our data suggest that EC damage results in the release of EMPs with a high content of calcium and BMP-2 that are able to induce calcification and osteogenic differentiation of VSMCs. PMID:25342130

  4. Governing Principles of Alginate Microparticle Synthesis with Centrifugal Forces.

    PubMed

    Eral, Huseyin Burak; Safai, Eric R; Keshavarz, Bavand; Kim, Jae Jung; Lee, Jisoek; Doyle, P S

    2016-07-19

    A controlled synthesis of polymeric particles is becoming increasingly important because of emerging applications ranging from medical diagnostics to self-assembly. Centrifugal synthesis of hydrogel microparticles is a promising method, combining rapid particle synthesis and the ease of manufacturing with readily available laboratory equipment. This method utilizes centrifugal forces to extrude an aqueous polymer solution, sodium alginate (NaALG) through a nozzle. The extruded solution forms droplets that quickly cross-link upon contact with aqueous calcium chloride (CaCl2) solution to form hydrogel particles. The size distribution of hydrogel particles is dictated by the pinch-off behavior of the extruded solution through a balance of inertial, viscous, and surface tension stresses. We identify the parameters dictating the particle size and provide a numerical correlation predicting the average particle size. Furthermore, we create a phase map identifying different pinch-off regimes (dripping without satellites, dripping with satellites, and jetting), explaining the corresponding particle size distributions, and present scaling arguments predicting the transition between regimes. By shedding light on the underlying physics, this study enables the rational design and operation of particle synthesis by centrifugal forces.

  5. Phoretic and Radiometric Force Measurements on Microparticles in Microgravity Conditions

    NASA Technical Reports Server (NTRS)

    Davis, E. James

    1996-01-01

    Thermophoretic, diffusiophoretic and radiometric forces on microparticles are being measured over a wide range of gas phase and particle conditions using electrodynamic levitation of single particles to simulate microgravity conditions. The thermophoretic force, which arises when a particle exists in a gas having a temperature gradient, is measured by levitating an electrically charged particle between heated and cooled plates mounted in a vacuum chamber. The diffusiophoretic force arising from a concentration gradient in the gas phase is measured in a similar manner except that the heat exchangers are coated with liquids to establish a vapor concentration gradient. These phoretic forces and the radiation pressure force acting on a particle are measured directly in terms of the change in the dc field required to levitate the particle with and without the force applied. The apparatus developed for the research and the experimental techniques are discussed, and results obtained by thermophoresis experiments are presented. The determination of the momentum and energy accommodation coefficients associated with molecular collisions between gases molecules and particles and the measurement of the interaction between electromagnetic radiation and small particles are of particular interest.

  6. Nanoparticles and microparticles for drug and vaccine delivery.

    PubMed Central

    Kreuter, J

    1996-01-01

    Nanoparticles are polymeric particles in the nanometer size range whereas microparticles are particles in the micrometre size range. Both types of particle are used as drug carriers into which drugs or antigens may be incorporated in the form of solid solutions or solid dispersions or onto which these materials may be absorbed or chemically bound. These particles have been shown to enhance the delivery of certain drugs across a number of natural and artificial membranes. In addition, the particles were shown to accumulate in areas of the intestine that appear to be the Peyer's patches. Possibly because of the combination of both effects these particles were able to significantly improve the bioavailability of some drugs after peroral administration in comparison with solutions. Recently nanoparticles coated with polysorbate 80 enabled the passage of small peptides and other drugs across the blood-brain barrier and the exhibition of a pharmacological effect after intravenous injection. Without the use of this type of nanoparticles the drugs did not cross this barrier and yielded no effect. PMID:8982823

  7. Governing Principles of Alginate Microparticle Synthesis with Centrifugal Forces.

    PubMed

    Eral, Huseyin Burak; Safai, Eric R; Keshavarz, Bavand; Kim, Jae Jung; Lee, Jisoek; Doyle, P S

    2016-07-19

    A controlled synthesis of polymeric particles is becoming increasingly important because of emerging applications ranging from medical diagnostics to self-assembly. Centrifugal synthesis of hydrogel microparticles is a promising method, combining rapid particle synthesis and the ease of manufacturing with readily available laboratory equipment. This method utilizes centrifugal forces to extrude an aqueous polymer solution, sodium alginate (NaALG) through a nozzle. The extruded solution forms droplets that quickly cross-link upon contact with aqueous calcium chloride (CaCl2) solution to form hydrogel particles. The size distribution of hydrogel particles is dictated by the pinch-off behavior of the extruded solution through a balance of inertial, viscous, and surface tension stresses. We identify the parameters dictating the particle size and provide a numerical correlation predicting the average particle size. Furthermore, we create a phase map identifying different pinch-off regimes (dripping without satellites, dripping with satellites, and jetting), explaining the corresponding particle size distributions, and present scaling arguments predicting the transition between regimes. By shedding light on the underlying physics, this study enables the rational design and operation of particle synthesis by centrifugal forces. PMID:27311392

  8. Characteristics of uranium carbonitride microparticles synthesized using different reaction conditions

    SciTech Connect

    Silva, Chinthaka M; Lindemer, Terrence; Voit, Stewart L; Hunt, Rodney Dale; Besmann, Theodore M; Terrani, Kurt A; Snead, Lance Lewis

    2014-11-01

    Three sets of different experimental conditions by changing the cover gases during the sample preparation were tested to synthesize uranium carbonitride (UC1-xNx) microparticles. In the first two sets of experiments using (N2 to N2-4%H2 to Ar) and (Ar to N2 to Ar) environments, single phase UC1-xNx was synthesized. When reducing environments (Ar-4%H2 to N2-4%H2 to Ar-4%H2) were utilized, theoretical densities up to 97% of single phase UC1-xNx kernels were obtained. Physical and chemical characteristics such as density, phase purity, and chemical compositions of the synthesized UC1-xNx materials for the diferent experimental conditions used are provided. In-depth analysis of the microstrutures of UC1-xNx has been carried out and is discussed with the objective of large batch fabrication of high density UC1-xNx kernels.

  9. Prokaryotic and eukaryotic airborne microorganisms as tracers of microclimatic changes in the underground (Postojna Cave, Slovenia).

    PubMed

    Mulec, Janez; Vaupotič, Janja; Walochnik, Julia

    2012-10-01

    Bioaerosols in cave air can serve as natural tracers and, together with physical parameters, give a detailed view of conditions in the cave atmosphere and responses to climatic changes. Airborne microbes in the Postojna Cave system indicated very dynamic atmospheric conditions, especially in the transitory seasonal periods between winter and summer. Physical parameters of cave atmosphere explained the highest variance in structure of microbial community in the winter and in the summer. The airborne microbial community is composed of different microbial groups with generally low abundances. At sites with elevated organic input, occasional high concentrations of bacteria and fungi can be expected of up to 1,000 colony-forming units/m(3) per individual group. The most abundant group of airborne amoebozoans were the mycetozoans. Along with movements of air masses, airborne algae also travel deep underground. In a cave passage with elevated radon concentration (up to 60 kBq/m(3)) airborne biota were less abundant; however, the concentration of DNA in the air was comparable to that in other parts of the cave. Due to seasonal natural air inflow, high concentrations of biological and inanimate particles are introduced underground. Sedimentation of airborne allochthonous material might represent an important and continuous source of organic material for cave fauna. PMID:22570119

  10. Formulation of porous poly(lactic-co-glycolic acid) microparticles by electrospray deposition method for controlled drug release.

    PubMed

    Hao, Shilei; Wang, Yazhou; Wang, Bochu; Deng, Jia; Zhu, Liancai; Cao, Yang

    2014-06-01

    In the present study, the electrospray deposition was successfully applied to prepare the porous poly(lactic-co-glycolic acid) (PLGA) microparticles by one-step processing. Metronidazole was selected as the model drug. The porous PLGA microparticles had high drug loading and low density, and the porous structure can be observed by scanning electron microscope (SEM) and transmission electron microscopy (TEM). The production time has been shortened considerably compared with that of the traditional multi-emulsion method. In addition, no chemical reaction occurred between the drug and polymer in the preparation of porous microparticles, and the crystal structure of drug did not change after entrapment into the porous microparticles. The porous microparticles showed a sustained release in the simulated gastric fluid, and the release followed non-Fickian or case II transport. Furthermore, porous microparticles showed a slight cytotoxicity in vitro. The results indicated that electrospray deposition is a good technique for preparation of porous microparticles, and the low-density porous PLGA microparticles has a potential for the development of gastroretentive systems or for pulmonary drug delivery.

  11. Formulation of porous poly(lactic-co-glycolic acid) microparticles by electrospray deposition method for controlled drug release.

    PubMed

    Hao, Shilei; Wang, Yazhou; Wang, Bochu; Deng, Jia; Zhu, Liancai; Cao, Yang

    2014-06-01

    In the present study, the electrospray deposition was successfully applied to prepare the porous poly(lactic-co-glycolic acid) (PLGA) microparticles by one-step processing. Metronidazole was selected as the model drug. The porous PLGA microparticles had high drug loading and low density, and the porous structure can be observed by scanning electron microscope (SEM) and transmission electron microscopy (TEM). The production time has been shortened considerably compared with that of the traditional multi-emulsion method. In addition, no chemical reaction occurred between the drug and polymer in the preparation of porous microparticles, and the crystal structure of drug did not change after entrapment into the porous microparticles. The porous microparticles showed a sustained release in the simulated gastric fluid, and the release followed non-Fickian or case II transport. Furthermore, porous microparticles showed a slight cytotoxicity in vitro. The results indicated that electrospray deposition is a good technique for preparation of porous microparticles, and the low-density porous PLGA microparticles has a potential for the development of gastroretentive systems or for pulmonary drug delivery. PMID:24863206

  12. Single immunization with a suboptimal antigen dose encapsulated into polyanhydride microparticles promotes high titer and avid antibody responses

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Microparticle adjuvants based on biodegradable polyanhydrides were used to provide controlled delivery of a model antigen, ovalbumin (Ova), to mice. Ova was encapsulated into two different polyanhydride microparticle formulations to evaluate the influence of polymer chemistry on the nature and magn...

  13. Geophex Airborne Unmanned Survey System

    SciTech Connect

    Won, I.L.; Keiswetter, D.

    1995-12-31

    Ground-based surveys place personnel at risk due to the proximity of buried unexploded ordnance (UXO) items or by exposure to radioactive materials and hazardous chemicals. The purpose of this effort is to design, construct, and evaluate a portable, remotely-piloted, airborne, geophysical survey system. This non-intrusive system will provide stand-off capability to conduct surveys and detect buried objects, structures, and conditions of interest at hazardous locations. During a survey, the operators remain remote from, but within visual distance of, the site. The sensor system never contacts the Earth, but can be positioned near the ground so that weak geophysical anomalies can be detected. The Geophex Airborne Unmanned Survey System (GAUSS) is designed to detect and locate small-scale anomalies at hazardous sites using magnetic and electromagnetic survey techniques. The system consists of a remotely-piloted, radio-controlled, model helicopter (RCH) with flight computer, light-weight geophysical sensors, an electronic positioning system, a data telemetry system, and a computer base-station. The report describes GAUSS and its test results.

  14. Airborne cw Doppler lidar (ADOLAR)

    NASA Astrophysics Data System (ADS)

    Rahm, Stefan; Werner, Christian; Nagel, E.; Herrmann, H.; Klier, M.; Knott, H. P.; Haering, R.; Wildgruber, J.

    1994-12-01

    During the last 10 years the DLR container LDA (Laser Doppler Anemometer) was used for many wind related measurements in the atmospheric boundary layer. The experience out of this were used to construct an airborne Doppler lidar ADOLAR. Based on the available Doppler lidars it is now proposed to perform a campaign to demonstrate the concept of the spaceborne sensor ALADIN, and to answer some questions concerning the signal quality from clouds, water and land. For the continuous wave CO2 laser, the energy is focused by the telescope into the region of investigation. Some of the radiation is back scattered by small aerosol particles drifting with the wind speed through the sensing volume. The back scattered radiation is collected by the telescope and detected by coherent technique. With the laser Doppler method one gets the radial wind component. To determine the magnitude and direction of the horizontal wind, some form of scanning in azimuth and elevation is required. To keep the airborne system compact, the transceiver optics is directly coupled to a wedge scanner which provides the conical scan with the axis in Nadir direction from the aircraft. The system ADOLAR was tested in 1994. Results of the flight over the lake Ammersee are presented and are compared with the data of the inertial reference system of the aircraft.

  15. Airborne thermography applications in Argentina

    NASA Astrophysics Data System (ADS)

    Castro, Eduardo H.; Selles, Eduardo J.; Costanzo, Marcelo; Franco, Oscar; Diaz, Jose

    2002-03-01

    Forest fires in summer and sheep buried under the snow in winter have become important problems in the south of our country, in the region named Patagonia. We are studying to find a solution by means of an airborne imaging system whose construction we have just finished. It is a 12 channel multispectral airborne scanner system that can be mounted in a Guarani airplane or in a Learjet; the first is a non- pressurized aircraft for flight at low height and the second is a pressurized one for higher flights. The scanner system is briefly described. Their sensors can detect radiation from the ultra violet to the thermal infrared. The images are visualized in real time in a monitor screen and can be stored in the hard disc of the PC for later processing. The use of this scanner for some applications that include the prevention and fighting of forest fires and the study of the possibility of detection of sheep under snow in the Patagonia is now being accomplished. Theoretical and experimental results in fire detection and a theoretical model for studying the possibility of detection of the buried sheep are presented.

  16. Microfabrication-derived DDS: From batch to individual production.

    PubMed

    Takada, K

    2008-06-01

    As a result of recent advances in microfabrication technology (MFT), microparticles including microcapsules and microspheres can be prepared individually and the disadvantages of the conventional microparticles produced by batch production, i.e. (i) low loading efficiency, (ii) large size variation, and (iii) initial burst release, have been remedied. In addition, all conventional microparticles have the same structure, a spherical shape, so they have only one function, sustained release. Threelayer microcapsules (TLMCs) have been designed to address these issues. TLMCs consist of a surface layer, a drug carrying layer, and a basement layer. TLMCs have sustained release as well as adhesiveness and targeting functions. TLMCs are prepared using ink-jet printer nozzle technology. The obtained TLMCs are used for the oral delivery of peptide/protein drugs and long-term sustained-release injection preparation. In addition, self-dissolving micropiles (SDMPs) can be individually produced by MFT as a percutaneous preparation. MFT allows biopharmaceutical drugs like insulin, erythropoietin, and growth hormone to be absorbed through the skin. Thus, advances in MFT have accelerated the development of pharmaceutical technology.

  17. Facile moldless fabrication of disk-shaped and reed blood cell-like microparticles using photopolymerization of tripropylene glycol diacrylate

    NASA Astrophysics Data System (ADS)

    Choi, Jongchul; Won, June; Song, Simon

    2014-12-01

    A facile method for the moldless fabrication of 2- or 3-dimensional microparticles is proposed by using a photopolymerization technique. Using only a monomer solution of tripropylene glycol diacrylate, a film mask and standard UV lithography equipment, we were able to fabricate microparticles of various shapes, such as disks, dimpled disks similar in shape to red blood cells, and slender gourd shapes, unlike previous moldless fabrication techniques requiring expensive and/or sophisticated equipment. The simple method could produce more than one million particles in a single batch, indicating that it can be applied to the mass production of polymer microparticles. Analyses of scanning electron micrographs and optical micrographs of the microparticles indicated that their size distribution was highly monodisperse. Detailed fabrication processes and statistics on the microparticle sizes are given in this paper.

  18. Safety Performance of Airborne Separation: Preliminary Baseline Testing

    NASA Technical Reports Server (NTRS)

    Consiglio, Maria C.; Hoadley, Sherwood T.; Wing, David J.; Baxley, Brian T.

    2007-01-01

    The Safety Performance of Airborne Separation (SPAS) study is a suite of Monte Carlo simulation experiments designed to analyze and quantify safety behavior of airborne separation. This paper presents results of preliminary baseline testing. The preliminary baseline scenario is designed to be very challenging, consisting of randomized routes in generic high-density airspace in which all aircraft are constrained to the same flight level. Sustained traffic density is varied from approximately 3 to 15 aircraft per 10,000 square miles, approximating up to about 5 times today s traffic density in a typical sector. Research at high traffic densities and at multiple flight levels are planned within the next two years. Basic safety metrics for aircraft separation are collected and analyzed. During the progression of experiments, various errors, uncertainties, delays, and other variables potentially impacting system safety will be incrementally introduced to analyze the effect on safety of the individual factors as well as their interaction and collective effect. In this paper we report the results of the first experiment that addresses the preliminary baseline condition tested over a range of traffic densities. Early results at five times the typical traffic density in today s NAS indicate that, under the assumptions of this study, airborne separation can be safely performed. In addition, we report on initial observations from an exploration of four additional factors tested at a single traffic density: broadcast surveillance signal interference, extent of intent sharing, pilot delay, and wind prediction error.

  19. NASA's Student Airborne Research Program (2009-2013)

    NASA Astrophysics Data System (ADS)

    Schaller, E. L.; Shetter, R. E.

    2013-12-01

    The NASA Student Airborne Research Program (SARP) is a unique summer internship program for rising senior undergraduates majoring in any of the STEM disciplines. SARP participants acquire hands-on research experience in all aspects of an airborne research campaign, including flying onboard an major NASA resource used for studying Earth system processes. In summer 2013, thirty-two participants worked in four interdisciplinary teams to study surface, atmospheric, and oceanographic processes. Participants assisted in the operation of instruments onboard the NASA DC-8 aircraft where they sampled and measured atmospheric gases and imaged land and water surfaces in multiple spectral bands. Along with airborne data collection, students participated in taking measurements at field sites. Mission faculty and research mentors helped to guide participants through instrument operation, sample analysis, and data reduction. Over the eight-week program, each student developed an individual research project from the data collected and delivered a conference-style final presentation on his/her results. Several students will present the results of their research in science sessions at this meeting. We will discuss the results and effectiveness of the program over the past five summers and plans for the future.

  20. Sterilization of auto-crosslinked hyaluronic acid scaffolds structured in microparticles and sponges.

    PubMed

    Shimojo, Andréa Arruda Martins; de Souza Brissac, Isabela Cambraia; Pina, Lucas Martins; Lambert, Carlos Salles; Santana, Maria Helena Andrade

    2015-01-01

    This work evaluated the effects of UV irradiation, plasma radiation, steam and 70% ethanol treatments on the sterilization and integrity of auto-crosslinked hyaluronic acid (HA-ACP) scaffolds structured in microparticles and sponges aiming in vivo applications for regenerative medicine of bone tissue. The integrity of the microparticles was characterized by rheological behavior, while for the sponges, it was characterized by scanning electron microscopy, Fourier transform infrared spectroscopy and differential scanning calorimetry. The effectiveness of the sterilization treatment was verified by the number of microorganism colonies in the samples after the treatments. In conclusion, plasma radiation was the best treatment for the sponges, while steam sterilization in the autoclave at 126°C (1.5 kgf/cm2) for 5 min was the best treatment for the microparticles. PMID:26684890

  1. Microparticles manipulation and enhancement of their separation in pinched flow fractionation by insulator-based dielectrophoresis.

    PubMed

    Khashei, Hesamodin; Latifi, Hamid; Seresht, Mohsen Jamshidi; Ghasemi, Amir Hossein Baradaran

    2016-03-01

    The separation and manipulation of microparticles in lab on a chip devices have importance in point of care diagnostic tools and analytical applications. The separation and sorting of particles from biological and clinical samples can be performed using active and passive techniques. In passive techniques, no external force is applied while in active techniques by applying external force (e.g. electrical), higher separation efficiency is obtained. In this article, passive (pinched flow fractionation) and active (insulator-based dielectrophoresis) methods were combined to increase the separation efficiency at lower voltages. First by simulation, appropriate values of geometry and applied voltages for better focusing, separation, and lower Joule heating were obtained. Separation of 1.5 and 6 μm polystyrene microparticles was experimentally obtained at optimized geometry and low total applied voltage (25 V). Also, the trajectory of 1.5 μm microparticles was controlled by adjusting the total applied voltage.

  2. Hierarchically Self-Assembled Star-Shaped ZnO Microparticles for Electrochemical Sensing of Amines.

    PubMed

    Du, Jianping; Huang, Xiaoxi; Zhao, Ruihua; Li, Jinping; Asefa, Tewodros

    2016-06-01

    Novel, hierarchically nanostructured, star-shaped ZnO (SSZ) microparticles are synthesized by a hydrothermal synthetic route. The SSZ microparticles serve as effective platforms for electrochemical detection of amines in solution. The morphology and structure of the materials are characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Raman spectroscopy, and UV/Vis spectroscopy. The as-synthesized SSZ microparticles comprise self-assembled hexagonal prisms that possess nanometer and micrometer pores in their structure and on their surfaces-structural features that are conducive to sensing applications. An electrode fabricated by using the hierarchically nanostructured SSZ materials serve as a sensitive electrochemical sensor for detection of low concentrations of ethylenediamine, with a sensitivity of 2.98×10(-2)  mA cm(-2)  mm(-1) , a detection limit of 2.36×10(-2)  mm, and a short response time of 8 s. PMID:27017147

  3. Mode-based microparticle conveyor belt in air-filled hollow-core photonic crystal fiber.

    PubMed

    Schmidt, Oliver A; Euser, Tijmen G; Russell, Philip St J

    2013-12-01

    We show how microparticles can be moved over long distances and precisely positioned in a low-loss air-filled hollow-core photonic crystal fiber using a coherent superposition of two co-propagating spatial modes, balanced by a backward-propagating fundamental mode. This creates a series of trapping positions spaced by half the beat-length between the forward-propagating modes (typically a fraction of a millimeter). The system allows a trapped microparticle to be moved along the fiber by continuously tuning the relative phase between the two forward-propagating modes. This mode-based optical conveyor belt combines long-range transport of microparticles with a positional accuracy of 1 µm. The technique also has potential uses in waveguide-based optofluidic systems. PMID:24514492

  4. Internal structure of cesium-bearing radioactive microparticles released from Fukushima nuclear power plant

    NASA Astrophysics Data System (ADS)

    Yamaguchi, Noriko; Mitome, Masanori; Kotone, Akiyama-Hasegawa; Asano, Maki; Adachi, Kouji; Kogure, Toshihiro

    2016-02-01

    Microparticles containing substantial amounts of radiocesium collected from the ground in Fukushima were investigated mainly by transmission electron microscopy (TEM) and X-ray microanalysis with scanning TEM (STEM). Particles of around 2 μm in diameter are basically silicate glass containing Fe and Zn as transition metals, Cs, Rb and K as alkali ions, and Sn as substantial elements. These elements are homogeneously distributed in the glass except Cs which has a concentration gradient, increasing from center to surface. Nano-sized crystallites such as copper- zinc- and molybdenum sulfide, and silver telluride were found inside the microparticles, which probably resulted from the segregation of the silicate and sulfide (telluride) during molten-stage. An alkali-depleted layer of ca. 0.2 μm thick exists at the outer side of the particle collected from cedar leaves 8 months after the nuclear accident, suggesting gradual leaching of radiocesium from the microparticles in the natural environment.

  5. High-frequency poly(vinylidene fluoride) copolymer transducers used for spectral characterization of settled microparticles

    NASA Astrophysics Data System (ADS)

    Melandsø, Frank; Wagle, Sanat; Decharat, Adit; Habib, Anowarul; Ahluwalia, Balpreet S.

    2016-07-01

    High-frequency ultrasonic polymer transducers are used to investigate backscattering from spherical microparticles. These microspheres are immersed in water and allowed to settle on a polymer substrate acting as an ultrasonic contact material between the immersion fluid and the transducer. The experimental study is complemented with a three-dimensional (3D) numerical investigation; both yield rather long scattered waveforms in the time domain for the largest microparticles. The corresponding frequency spectra typically contain a number of minima values arising from wave resonances in the microparticles. The locations of these resonances, or eigenvalues, correlate strongly to the particle size. Good agreement is obtained between the experiment and the numerical model, which will help to identify the wave mode responsible for the extended scattering.

  6. Single-, few-, and multilayer graphene not exhibiting significant advantages over graphite microparticles in electroanalysis.

    PubMed

    Goh, Madeline Shuhua; Pumera, Martin

    2010-10-01

    This report compares the electroanalytical performances of single- (G-SL), few- (G-FL), and multilayer graphene (G-ML), graphite microparticles, and edge-plane pyrolytic graphite electrodes in terms of sensitivity, linearity, and repeatability. We show that in the case of differential pulse voltammetric (DPV) detection of ascorbic acid, the sensitivity of a G-SL electrode is about 30% greater than that of G-ML and about 40% greater than graphite microparticles. However, in the case of DPV determination of uric acid, sensitivity is practically the same for all (G-SL, G-FL, and G-ML) and, importantly, the graphite microparticles do provide higher sensitivity than graphenes do for this analyte. Graphenes also do not provide a significant advantage in terms of repeatability. We pose the question of whether the efforts leading to the bulk method of producing single-layer graphene are justified for electroanalytical applications.

  7. CTL responses induced by a single immunization with peptide encapsulated in biodegradable microparticles.

    PubMed

    Partidos, C D; Vohra, P; Jones, D; Farrar, G; Steward, M W

    1997-08-01

    A synthetic peptide representing a measles virus (MV) cytotoxic T cell epitope (CTL) when encapsulated in poly (D,L-lactide co-glycolide) (PLG) 50:50 microparticles induced a strong CTL response after a single intraperitoneal immunization of mice which was greater than that following administration of the peptide in Freund's complete adjuvant. A 100 micrograms dose of encapsulated peptide was shown to be more effective for CTL priming than 50 and 25 micrograms doses. A vaccine formulation prepared by simply mixing empty 50:50 PLG microparticles with the peptide resulted in the induction of CTL responses comparable to those induced by the encapsulated peptide. Moreover, a CTL response against MV-infected target cells was observed. These findings highlight the potential immunostimulatory effect of PLG microparticles for the induction of MV and peptide-specific CTL responses.

  8. Elaboration of microparticles of carotenoids from natural and synthetic sources for applications in food.

    PubMed

    Rutz, Josiane K; Borges, Caroline D; Zambiazi, Rui C; da Rosa, Cleonice G; da Silva, Médelin M

    2016-07-01

    Carotenoids are susceptible to isomerization and oxidation upon exposure to oxygen, light and heat, which can result in loss of color, antioxidant activity, and vitamin activity. Microencapsulation helps retain carotenoid stability and promotes their release under specific conditions. Thus, the aim of the study was to encapsulate palm oil and β-carotene with chitosan/sodium tripolyphosphate or chitosan/carboxymethylcellulose and to assess the performance of these microparticles in food systems by analyzing their release profile under simulated gastric and intestinal conditions. Encapsulation efficiency was greater than 95%, and the yield of microparticles coated with chitosan/sodium tripolyphosphate was approximately 55%, while that of microparticles coated with chitosan/carboxymethylcellulose was 87%. Particles encapsulated with chitosan/carboxymethylcellulose exhibited ideal release behavior in water and gastric fluid, but showed low release in the intestinal fluid. However, when applied to food systems these particles showed enhanced carotenoid release but showed low release of carotenoids upon storage. PMID:26920301

  9. Periodontitis as a risk factor for systemic disease: Are microparticles the missing link?

    PubMed

    Badran, Zahi; Struillou, Xavier; Verner, Christian; Clee, Thibaud; Rakic, Mia; Martinez, Maria C; Soueidan, Assem

    2015-06-01

    Periodontitis is an oral inflammatory disease affecting the teeth supportive tissue. Its bacterial infectious etiology is well established. Periodontitis has been associated with increased prevalence of systemic diseases such as cardiovascular diseases, diabetes, rheumatoid arthritis, preeclampsia, preterm birth and inflammatory bowel disease. The rational of considering periodontitis as risk factor for systemic disease is the passage of inflammatory cytokines and/or bacteria in the bloodstream, thus affecting distant organs. Membrane microparticles are released by multiple cells in inflammatory environment. Recent data suggested the role of these microparticles in the pathogenic process of many systemic diseases, that can be also associated to periodontitis. We hypothesized that periodontitis could be a chronic reservoir of microparticles, hence elucidating partially the interaction with systemic diseases initiation or progression.

  10. Recombinant human elastin-like magnetic microparticles for drug delivery and targeting.

    PubMed

    Ciofani, Gianni; Genchi, Giada Graziana; Guardia, Pablo; Mazzolai, Barbara; Mattoli, Virgilio; Bandiera, Antonella

    2014-05-01

    Bioinspired recombinant polypeptides represent a highly promising tool in biomedical research, being protein intrinsic constituents of both cells and their natural matrices. In this regard, a very interesting model is represented by polypeptides inspired by elastin, which naturally confers rubber-like elasticity to tissues, and is able to undergo wide deformations without rupture. In this paper, a microparticle system based on a recombinant human elastin-like polypeptide (HELP) is reported for drug delivery applications. HELP microparticles are prepared through a water-in-oil emulsion of an aqueous solution of recombinant polypeptide in isoctane, followed by enzymatic cross-linking. Superparamagnetic iron oxide nanoparticles are introduced in this system with the purpose of conferring magnetic properties to the microspheres, and thus controlling their targeting and tracking as drug vectors. The obtained microparticles are characterized in terms of morphology, structure, magnetic properties, drug release, and magnetic drivability, showing interesting and promising results for further biomedical applications. PMID:24318291

  11. Manipulation of micro-particles by flexible polymer-based optically-induced dielectrophoretic devices.

    PubMed

    Lin, Shu-Ju; Hung, Shih-Hsun; Jeng, Jun-Yuan; Guo, Tzung-Fang; Lee, Gwo-Bin

    2012-01-01

    This study presents a novel technology to manipulate micro-particles with the assistance from flexible polymer-based optically-induced dielectrophoretic (ODEP) devices. Bending the flexible ODEP devices downwards or upwards to create convex or concave curvatures, respectively, enables the more effective separation or collection of micro-particles with different diameters. The travel distances of the polystyrene beads of 40 μm diameter, as induced by the projected light in a given time period was increased by ~100%, which were 43.0 ± 5.0 and 84.6 ± 4.0 μm for flat and convex ODEP devices, respectively. A rapid separation or collection of micro-particles can be achieved with the assistance of gravity because the falling polystyrene beads followed the inclination of the downward and upward bent ODEP devices.

  12. A microfluidic chip using phenol formaldehyde resin for uniform-sized polycaprolactone and chitosan microparticle generation.

    PubMed

    Lin, Yung-Sheng; Yang, Chih-Hui; Wu, Chin-Tung; Grumezescu, Alexandru Mihai; Wang, Chih-Yu; Hsieh, Wan-Chen; Chen, Szu-Yu; Huang, Keng-Shiang

    2013-01-01

    This study develops a new solvent-compatible microfluidic chip based on phenol formaldehyde resin (PFR). In addition to its solvent-resistant characteristics, this microfluidic platform also features easy fabrication, organization, decomposition for cleaning, and reusability compared with conventional chips. Both solvent-dependent (e.g., polycaprolactone) and nonsolvent-dependent (e.g., chitosan) microparticles were successfully prepared. The size of emulsion droplets could be easily adjusted by tuning the flow rates of the dispersed/continuous phases. After evaporation, polycaprolactone microparticles ranging from 29.3 to 62.7 μm and chitosan microparticles ranging from 215.5 to 566.3 μm were obtained with a 10% relative standard deviation in size. The proposed PFR microfluidic platform has the advantages of active control of the particle size with a narrow size distribution as well as a simple and low cost process with a high throughput. PMID:23736788

  13. Enzyme encapsulation in magnetic chitosan-Fe3O4 microparticles.

    PubMed

    Costa-Silva, Tales Alexandre; Marques, Polyana Samorano; Souza, Cláudia Regina Fernandes; Said, Suraia; Oliveira, Wanderley Pereira

    2015-01-01

    Two simple procedures for the preparation of magnetic chitosan enzyme microparticles have been investigated and used for the immobilisation of endophytic fungus Cercospora kikuchii lipase as model enzyme. In the first case, lipase was entrapped in Fe3O4-chitosan microparticles by cross-linking method, while in the second case magnetic immobilised derivatives were produced using spray drying. Immobilised enzymes showed high enzyme activity retention and stability during storage without significant loss of activity. Glutaraldehyde Fe3O4-chitosan powders presented a higher lipase activity retention and storage stability than the others preparations. However, the immobilised derivatives produced by cross-linking showed higher enzyme activity after reuse cycles. The results proved that the magnetic Fe3O4-chitosan microparticles are an effective support for the enzyme immobilisation since the immobilised lipase showed best properties than the free form.

  14. Activity of spray-dried microparticles containing pomegranate peel extract against Candida albicans.

    PubMed

    Endo, Eliana Harue; Ueda-Nakamura, Tânia; Nakamura, Celso Vataru; Filho, Benedito Prado Dias

    2012-01-01

    Pomegranate has attracted interest from researchers because of its chemical composition and biological properties. It possesses strong antioxidant activity, with potential health benefits, and also antimicrobial properties. The aim of this study was to produce microparticles containing pomegranate extract by the spray-drying technique, utilizing alginate or chitosan as encapsulating agents. Characterization and antifungal assays were carried out. Production yields were about 40% for alginate microparticles and 41% for chitosan. Mean diameters were 2.45 µm and 2.80 µm, and encapsulation efficiencies were 81.9% and 74.7% for alginate and chitosan microparticles, respectively. The spray-drying process preserved the antifungal activity against Candida albicans. These results could be useful for developing dosage forms for treating candidiasis, and should be further investigated in in vivo models. PMID:22922280

  15. Design and characterization of bi-soft segmented polyurethane microparticles for biomedical application.

    PubMed

    Campos, Elisa; Cordeiro, Rosemeyre; Santos, Ana Cristina; Matos, Cláudia; Gil, M H

    2011-11-01

    Bi-soft segmented poly(ester urethane urea) microparticles were prepared and characterized aiming a biomedical application. Two different formulations were developed, using poly(propylene glycol), tolylene 2,4-diisocyanate terminated pre-polymer (TDI) and poly(propylene oxide)-based tri-isocyanated terminated pre-polymer (TI). A second soft segment was included due to poly(ɛ-caprolactone) diol (PCL). Infrared spectroscopy, used to study the polymeric structure, namely its H-bonding properties, revealed a slightly higher degree of phase separation in TDI-microparticles. TI-microparticles presented slower rate of hydrolytic degradation, and, accordingly, fairly low toxic effect against macrophages. These new formulations are good candidates as non-biodegradable biomedical systems.

  16. Dynamic transformation of self-assembled structures using anisotropic magnetized hydrogel microparticles

    NASA Astrophysics Data System (ADS)

    Yoshida, Satoru; Takinoue, Masahiro; Iwase, Eiji; Onoe, Hiroaki

    2016-08-01

    This paper describes a system through which the self-assembly of anisotropic hydrogel microparticles is achieved, which also enables dynamic transformation of the assembled structures. Using a centrifuge-based microfluidic device, anisotropic hydrogel microparticles encapsulating superparamagnetic materials on one side are fabricated, which respond to a magnetic field. We successfully achieve dynamic assembly using these hydrogel microparticles and realize three different self-assembled structures (single and double pearl chain structures, and close-packed structures), which can be transformed to other structures dynamically via tuning of the precessional magnetic field. We believe that the developed system has potential application as an effective platform for a dynamic cell manipulation and cultivation system, in biomimetic autonomous microrobot organization, and that it can facilitate further understanding of the self-organization and complex systems observed in nature.

  17. Fabrication and application of porous silicon multilayered microparticles in sustained drug delivery

    NASA Astrophysics Data System (ADS)

    Maniya, Nalin H.; Patel, Sanjaykumar R.; Murthy, Z. V. P.

    2015-09-01

    In the present study, the ability of porous silicon (PSi) based distributed Bragg reflector (DBR) microparticles for sustained and observable delivery of the antiviral agent acyclovir (ACV) is demonstrated. DBR was fabricated by electrochemical etching of single crystal silicon wafers and ultrasonic fractured to prepare microparticles. The hydrogen-terminated native surface of DBR microparticles was modified by thermal oxidation and thermal hydrosilylation. Particles were loaded with ACV and drug release experiments were conducted in phosphate buffered saline. Drug loading and surface chemistry of particles were characterized by scanning electron microscopy and Fourier transform infrared spectroscopy. Drug release profiles from PSi DBR particles show sustained release behavior from all three studied surface chemistries. Drug release from particles was also monitored from change in color of particles.

  18. Three-Dimensional Complex-Shaped Photopolymerized Microparticles at Liquid Crystal Interfaces

    SciTech Connect

    Martinez, A.; Lee, T.; Asavei, T.; Rubinsztein-Dunlop, H.; Smalyukh, I. I.

    2012-02-28

    Microparticles of arbitrary shapes immersed in the bulk of nematic fluids are known to produce dipolar or quadrupolar elastic distortions that can mediate long-range colloidal interactions. We use two-photon photopolymerization to obtain complex-shaped surface-bound microparticles that are then embedded into a nematic liquid crystal host with a uniform far-field director. By means of three-dimensional imaging with multi-photon excitation fluorescence polarizing microscopy, we demonstrate low-symmetry, long-range elastic distortions induced by the particles in the liquid crystal director field. These director distortions may provide a means for controlling elastic interactions in liquid crystals between custom-designed photopolymerized microparticles attached to confining solid substrates and nematic fluid-borne colloids, thus enabling elasticity-mediated templated self-assembly.

  19. Silicon microfluidic flow focusing devices for the production of size-controlled PLGA based drug loaded microparticles.

    PubMed

    Keohane, Kieran; Brennan, Des; Galvin, Paul; Griffin, Brendan T

    2014-06-01

    The increasing realisation of the impact of size and surface properties on the bio-distribution of drug loaded colloidal particles has driven the application of micro fabrication technologies for the precise engineering of drug loaded microparticles. This paper demonstrates an alternative approach for producing size controlled drug loaded PLGA based microparticles using silicon Microfluidic Flow Focusing Devices (MFFDs). Based on the precise geometry and dimensions of the flow focusing channel, microparticle size was successfully optimised by modifying the polymer type, disperse phase (Qd) flow rate, and continuous phase (Qc) flow rate. The microparticles produced ranged in sizes from 5 to 50 μm and were highly monodisperse (coefficient of variation <5%). A comparison of Ciclosporin (CsA) loaded PLGA microparticles produced by MFFDs vs conventional production techniques was also performed. MFFDs produced microparticles with a narrower size distribution profile, relative to the conventional approaches. In-vitro release kinetics of CsA was found to be influenced by the production technique, with the MFFD approach demonstrating the slowest rate of release over 7 days (4.99 ± 0.26%). Finally, MFFDs were utilised to produce pegylated microparticles using the block co-polymer, PEG-PLGA. In contrast to the smooth microparticles produced using PLGA, PEG-PLGA microparticles displayed a highly porous surface morphology and rapid CsA release, with 85 ± 6.68% CsA released after 24h. The findings from this study demonstrate the utility of silicon MFFDs for the precise control of size and surface morphology of PLGA based microparticles with potential drug delivery applications.

  20. Sublingual injection of microparticles containing glycolipid ligands for NKT cells and subunit vaccines induces antibody responses in oral cavity

    PubMed Central

    DeLyria, Elizabeth S; Zhou, Dapeng; Lee, Jun Soo; Singh, Shailbala; Song, Wei; Li, Fenge; Sun, Qing; Lu, Hongzhou; Wu, Jinhui; Qiao, Qian; Hu, Yiqiao; Zhang, Guodong; Li, Chun; Sastry, K. Jagannadha; Shen, Haifa

    2014-01-01

    Natural Killer T (NKT) cells are a unique type of innate immune cells which exert paradoxical roles in animal models through producing either Th1 or Th2 cytokines and activating dendritic cells. Alpha-galactosylceramide (αGalCer), a synthetic antigen for NKT cells, was found to be safe and immune stimulatory in cancer and hepatitis patients. We recently developed microparticle-formulated αGalCer, which is selectively presented by dendritic cells and macrophages, but not B cells, and thus can avoid the anergy of NKT cells. In this study, we have examined the immunogenicity of microparticles containing αGalCer and protein vaccine components through sublingual injection in mice. The results showed that sublingual injection of microparticles containing αGalCer and ovalbumin triggered IgG responses in serum (titer >1:100,000), which persisted for more than 3 months. Microparticles containing ovalbumin alone also induced comparable level of IgG responses. However, immunoglobulin subclass analysis showed that sublingually injected microparticles containing αGalCer and ovalbumin induced 20 fold higher Th1 biased antibody (IgG2c) than microparticles containing OVA alone (1:20,000 as compared to 1:1000 titer). Sublingual injection of microparticles containing αGalCer and ovalbumin induced secretion of both IgG (titer >1:1000) and IgA (titer =1:80) in saliva secretion, while microparticles containing ovalbumin alone only induced secretion of IgG in saliva. Our results suggest that sublingual injection of microparticles and their subsequent trafficking to draining lymph nodes may induce adaptive immune responses in mucosal compartments. Ongoing studies are focused on the mechanism of antigen presentation and lymphocyte biology in the oral cavity, as well as the toxicity and efficacy of these candidate microparticles for future applications. PMID:25555750

  1. Sublingual injection of microparticles containing glycolipid ligands for NKT cells and subunit vaccines induces antibody responses in oral cavity.

    PubMed

    DeLyria, Elizabeth S; Zhou, Dapeng; Lee, Jun Soo; Singh, Shailbala; Song, Wei; Li, Fenge; Sun, Qing; Lu, Hongzhou; Wu, Jinhui; Qiao, Qian; Hu, Yiqiao; Zhang, Guodong; Li, Chun; Sastry, K Jagannadha; Shen, Haifa

    2015-03-20

    Natural Killer T (NKT) cells are a unique type of innate immune cells which exert paradoxical roles in animal models through producing either Th1 or Th2 cytokines and activating dendritic cells. Alpha-galactosylceramide (αGalCer), a synthetic antigen for NKT cells, was found to be safe and immune stimulatory in cancer and hepatitis patients. We recently developed microparticle-formulated αGalCer, which is selectively presented by dendritic cells and macrophages, but not B cells, and thus can avoid the anergy of NKT cells. In this study, we have examined the immunogenicity of microparticles containing αGalCer and protein vaccine components through sublingual injection in mice. The results showed that sublingual injection of microparticles containing αGalCer and ovalbumin triggered IgG responses in serum (titer >1:100,000), which persisted for more than 3months. Microparticles containing ovalbumin alone also induced comparable level of IgG responses. However, immunoglobulin subclass analysis showed that sublingually injected microparticles containing αGalCer and ovalbumin induced 20 fold higher Th1 biased antibody (IgG2c) than microparticles containing OVA alone (1:20,000 as compared to 1:1000 titer). Sublingual injection of microparticles containing αGalCer and ovalbumin induced secretion of both IgG (titer >1:1000) and IgA (titer=1:80) in saliva secretion, while microparticles containing ovalbumin alone only induced secretion of IgG in saliva. Our results suggest that sublingual injection of microparticles and their subsequent trafficking to draining lymph nodes may induce adaptive immune responses in mucosal compartments. Ongoing studies are focused on the mechanism of antigen presentation and lymphocyte biology in the oral cavity, as well as the toxicity and efficacy of these candidate microparticles for future applications.

  2. Semiconducting polypyrrole-polyacrylamide microparticles with entrapped Glucose Oxidase for application in biosensors

    NASA Astrophysics Data System (ADS)

    Lopez-Cabarcos, Enrique; Rubio-Retama, Jorge; Mecerreyes, David; Fernandez-Barbero, Antonio; Lopez-Ruiz, Beatriz

    2004-03-01

    We have immobilized water dispersed polypyrrole (PPy) and Glucose Oxidase (GOx) into polyacrylamide microparticles with the aim to use them as biological component in a glucose sensor. To produce the microparticles, PPy together with GOx and acrylamide were incorporated in the aqueous phase of a W/O concentrated emulsion which was polymerised. The content of PPy in the emulsion was varied and micropaticles with 10/90, 15/85, 25/75, 30/70, 40/60 and 50/50 polypyrrole/acrylamide (w/w in the aqueous phase) were obtained. The physical properties of the system were investigated and it was found that the electrical conductivity increases with the amount of PPy entrapped in the microparticles from 10-12 S/cm, for polyacrylamide microparticles, up to 10-5 S/cm for the 50/50 PPy/PA particles. The microparticles with immobilized GOx were used as biological component of an amperometric glucose sensor. To prepare the electrode, the 50/50 PPy/PA microparticles with GOx were selected because they show the best conductivity properties.The resulting electrode was subsequently placed in a three-electrode cell and acted as the working electrode. When working in aerobic conditions, an increase in current was observed upon addition of glucose. The average response time for glucose of this biosensor was 150nA/mM with a response time of 20 s. To work in anaerobic conditions, oxygen was removed from the cell by purging with nitrogen during 20 min. The response of the biosensor is similar in aerobic and anaerobic conditions indicating that polypyrrole acts as electron transfer material between the enzyme and the electrode.

  3. Development of enoxaparin sodium polymeric microparticles for colon-specific delivery

    PubMed Central

    HALES, DANA; CASTERAN, MAXIME; SAPIN-MINET, ANNE; TOMUŢA, IOAN; ACHIM, MARCELA; VLASE, LAURIAN; MAINCENT, PHILIPPE

    2015-01-01

    Background and aims Recent studies have shown that low molecular weight heparins are effective in the treatment of inflammatory bowel disease. Therefore, there is considerable interest in the development of an oral colonic delivery pharmaceutical system allowing targeted release of heparin in the inflamed tissue. The objective of this study was to prepare microparticles for the oral administration and colonic release of enoxaparin and to evaluate the influence of certain formulation factors on their characteristics. Methods Microparticles were prepared by water/oil/water double emulsion technique followed by solvent evaporation. The influence of several formulation factors on the characteristics of microparticles were evaluated. The formulation factors were alginate concentration in the inner aqueous phase, polymer (Eudragit® FS 30D and Eudragit® RS PO) concentration in the organic phase and ratios between the two polymers. The microparticles were characterized in terms of morphology, size, entrapment efficiency and enoxaparin release. Results The results showed that increasing sodium alginate percentage reduced the encapsulation efficiency of enoxaparin and accelerated enoxaparin release. Regarding the influence of the two polymers, reducing polymer concentration in the organic phase led to a smaller size of microparticles, a lower entrapment efficiency and an important retardation of enoxaparin release. The formulation prepared with Eudragit® FS 30D limited the release to a maximum of 3% in gastric simulated environment, a specific characteristic of oral systems for colonic delivery, and fulfilled our objective to delay the release. Conclusions Microparticles prepared with Eudragit® FS 30D represent a suitable and potential oral system for the colonic delivery of enoxaparin. PMID:26609270

  4. Multifunctional poly(β-amino ester) hydrogel microparticles in periodontal in situ forming drug delivery systems.

    PubMed

    Fisher, Paul D; Clemens, Justin; Zach Hilt, J; Puleo, David A

    2016-04-01

    In situ forming implants (ISIs) formed from poly(lactic-co-glycolic acid) (PLGA) have been commercialized for local drug delivery to treat periodontitis, but drug release from these bulk materials is typically subject to an initial burst. In addition, PLGA has inferior material properties for the dynamic mechanical environment of gingival tissue. In this work, poly(β-amino ester) (PBAE) hydrogel microparticles were incorporated into a PLGA matrix to provide several new functions: mechanical support, porosity, space-filling, and controlled co-delivery of antimicrobial and osteogenic drugs. First, the effects of PBAE microparticles on ISI architecture and material properties throughout degradation were investigated. Second, the influence of PBAE microparticles on drug release kinetics was quantified. Over a 15 d period, ISIs containing PBAE microparticles possessed greater porosity, ranging from 42-80%, compared to controls, which ranged from 24-54% (p < 0.001), and these ISIs also developed significantly greater accessible volume to simulated cell-sized spheres after 5 d or more of degradation (p < 0.001). PBAE-containing ISIs possessed a more uniform microarchitecture, which preserved mechanical resilience after cyclical loading (p < 0.001), and the materials swelled to fill the injected space, which significantly increased interfacial strength in an artificial periodontal pocket (p < 0.0001). PBAE microparticles eliminated the burst of freely-mixed simvastatin compared to 36% burst from controls (p < 0.0001), and high-dose doxycycline release was prolonged from 2 d to 7 d by pre-loading drug into the microparticles. PBAE-containing PLGA ISIs are more effective space-filling scaffolds and offer improved release kinetics compared to existing ISIs used to treat periodontitis. PMID:26947556

  5. External and Intraparticle Diffusion of Coumarin 102 with Surfactant in the ODS-silica Gel/water System by Single Microparticle Injection and Confocal Fluorescence Microspectroscopy.

    PubMed

    Nakatani, Kiyoharu; Matsuta, Emi

    2015-01-01

    The release mechanism of coumarin 102 from a single ODS-silica gel microparticle into the water phase in the presence of Triton X-100 was investigated by confocal fluorescence microspectroscopy combined with the single microparticle injection technique. The release rate significantly depended on the Triton X-100 concentration in the water phase and was not limited by diffusion in the pores of the microparticle. The release rate constant was inversely proportional to the microparticle radius squared, indicating that the rate-determining step is the external diffusion between the microparticle and the water phase.

  6. Gold Nanoplate-Based 3D Hierarchical Microparticles: A Single Particle with High Surface-Enhanced Raman Scattering Enhancement.

    PubMed

    Ma, Ying; Yung, Lin-Yue Lanry

    2016-08-01

    Formation of intended nano- and microstructures with regular building blocks has attracted much attention because of their potential applications in the fields of optics, electronics, and catalysis. Herein, we report a novel strategy to spontaneously grow three-dimensional (3D) hierarchical cabbagelike microparticles (CLMPs) constructed by individual Au nanoplates. By reducing gold precursor to gold atoms, N-(3-amidino)-aniline (NAAN) itself was oxidized to form poly(N-(3-amidino)-aniline) (PNAAN), which specifically binds on Au(111) facet as a capping agent and which leads to the formation of gold nanoplates. Because of the incomplete coverage of Au(111) facet, new gold nanoplate growth sites were spontaneously generated from the crystal plane of existing Au nanoplates for the growth of other nanoplates. This process continued until the nanoplate density reached its maximum range, eventually resulting in CLMPs with well-controlled structures. This opens a new avenue to utilize the imperfection during nanoparticle (NP) growth for the construction of microstructures. The individual CLMP shows excellent surface-enhanced Raman scattering (SERS) performance with high enhancement factor (EF) and good reproducibility as it integrates the SERS enhancement effects of individual Au nanoplate and the nanogaps formed by the uniform and hierarchical structures. PMID:27452074

  7. A composition analyzer for microparticles using a spark ion source. [using time of flight spectrometers

    NASA Technical Reports Server (NTRS)

    Auer, S. O.; Berg, O. E.

    1975-01-01

    Iron microparticles were fired onto a capacitor-type microparticle detector which responded to an impact with a spark discharge. Ion currents were extracted from the spark and analyzed in a time-of-flight mass spectrometer. The mass spectra showed the element of both detector and particle materials. The total extracted ion currents was typically 10A within a period of 100ns, indicating very efficient vaporization of the particle and ionization of the vapor. Potential applications include research on cosmic dust, atmospheric aerosols and cloud droplets, particles ejected by rocket or jet engines, by machining processes, or by nuclear bomb explosions.

  8. Biocompatibility Assessment of Si-based Nano- and Micro-particles

    PubMed Central

    Jaganathan, Hamsa; Godin, Biana

    2012-01-01

    Silicon is one of the most abundant chemical elements found on the Earth. Due to its unique chemical and physical properties, silicon based materials and their oxides (e.g. silica) have been used in several industries such as building and construction, electronics, food industry, consumer products and biomedical engineering/medicine. This review summarizes studies on effects of silicon and silica nano- and micro-particles on cells and organs following four main exposure routes, namely, intravenous, pulmonary, dermal and oral. Further, possible genotoxic effects of silica based nanoparticles are discussed. The review concludes with an outlook on improving and standardizing biocompatibility assessment for nano- and micro-particles. PMID:22634160

  9. Explosive vaporization of metallic sodium microparticles by CW resonant laser radiation.

    PubMed

    Atutov, S N; Baldini, W; Biancalana, V; Calabrese, R; Guidi, V; Mai, B; Mariotti, E; Mazzocca, G; Moi, L; Pod'yachev, S P; Tomassetti, L

    2001-11-19

    Explosive vaporization of metallic Na microparticles stimulated by resonant cw laser radiation has been observed in a glass cell. Vaporization occurs at low laser-power density. The effect consists in the generation of optically thick and sharply localized Na vapor clouds propagating in the cell against the laser beam. The effect is explained by laser excitation of Na atoms, which collide onto the surface of the microparticles and transfer their internal energy. This causes other atoms to be vaporized and to continue the avalanche process. PMID:11736344

  10. Explosive vaporization of metallic sodium microparticles by CW resonant laser radiation.

    PubMed

    Atutov, S N; Baldini, W; Biancalana, V; Calabrese, R; Guidi, V; Mai, B; Mariotti, E; Mazzocca, G; Moi, L; Pod'yachev, S P; Tomassetti, L

    2001-11-19

    Explosive vaporization of metallic Na microparticles stimulated by resonant cw laser radiation has been observed in a glass cell. Vaporization occurs at low laser-power density. The effect consists in the generation of optically thick and sharply localized Na vapor clouds propagating in the cell against the laser beam. The effect is explained by laser excitation of Na atoms, which collide onto the surface of the microparticles and transfer their internal energy. This causes other atoms to be vaporized and to continue the avalanche process.

  11. Optical Manipulation of Shape-Morphing Elastomeric Liquid Crystal Microparticles Doped with Gold Nanocrystals

    SciTech Connect

    Sun, Y. R.; Evans, J. S.; Lee, T.; Senyuk, B.; Keller, P.; He, S. L.; Smalyukh, I. I.

    2012-06-11

    We demonstrate facile optical manipulation of shape of birefringent colloidal microparticles made from liquid crystal elastomers. Using soft lithography and polymerization, we fabricate elastomeric microcylinders with weakly undulating director oriented on average along their long axes. These particles are infiltrated with gold nanospheres acting as heat transducers that allow for an efficient localized transfer of heat from a focused infrared laser beam to a submicrometer region within a microparticle. Photothermal control of ordering in the liquid crystal elastomer using scanned beams allows for a robust control of colloidal particles, enabling both reversible and irreversible changes of shape. Possible applications include optomechanics, microfluidics, and reconfigurable colloidal composites with shape-dependent self-assembly.

  12. Manipulation of micro-particles through optical interference patterns generated by integrated photonic devices.

    PubMed

    Hsu, Li-Chung; Chen, Te-Chang; Yang, Yao-Tsu; Huang, Chieh-Yang; Shen, Da-Wei; Chen, Ya-Tzu; Lee, Ming-Chang M

    2013-03-21

    Micro-particle transport and switch governed by guided-wave optical interference are presented. The optical interference, occurring in a directional coupler and a multi-mode interferometer made by inverted rib waveguides, results in a specific evanescent field dependent on wavelength. Through a detailed theoretical analysis, the field of induced optical force shows a correlative pattern associated with the evanescent field. Experimental results demonstrate that 10 μm polystyrene beads are propelled with a trajectory subject to the interference pattern accordingly. By launching different wavelengths, the polystyrene beads can be delivered to different output waveguide ports. Massive micro-particle manipulation is applicable.

  13. An on-line remote supervisory system for microparticles based on image analysis

    NASA Astrophysics Data System (ADS)

    Liu, Wei-Hua; Jiang, Ming-Shun; Sui, Qing-Mei

    2011-11-01

    A new on-line remote particle analysis system based on image processing has been developed to measure microparticles. The system is composed of particle collector sensor (PCS), particle image sensor (PIS), image remote transmit module and image processing system. Then some details of image processing are discussed. The main advantage of this system is more convenient in particle sample collection and particle image acquisition. The particle size can be obtained using the system with a deviation abot less than 1 μm, and the particle number can be obtained without deviation. The developed system is also convenient and versatile for other analyses of microparticle for academic and industrial application.

  14. Alginate-peptide amphiphile core-shell microparticles as a targeted drug delivery system

    PubMed Central

    Boekhoven, Job; Zha, R. Helen; Tantakitti, Faifan; Zhuang, Ellen; Zandi, Roya; Newcomb, Christina J.

    2015-01-01

    We describe in this work the synthesis of microparticles with a doxorubicin drug conjugated alginate core and a shell of peptide amphiphile nanofibres functionalized for targeting the folate receptor. The spherical geometry of the particle core allows high drug loading per surface area, whereas the nanoscale fibrous shell formed by self-assembly of peptide amphiphiles offers a high surface to volume ratio that is ideal for targeting. The synthesised microparticles have a 60-fold higher cytotoxicity against MDA-MB-231 breast cancer cells compared to non-targeting particles. PMID:25642326

  15. Platelet microparticles inhibit IL-17 production by regulatory T cells through P-selectin.

    PubMed

    Dinkla, Sip; van Cranenbroek, Bram; van der Heijden, Wouter A; He, Xuehui; Wallbrecher, Rike; Dumitriu, Ingrid E; van der Ven, André J; Bosman, Giel J C G M; Koenen, Hans J P M; Joosten, Irma

    2016-04-21

    Self-tolerance and immune homeostasis are orchestrated by FOXP3(+)regulatory T cells (Tregs). Recent data have revealed that upon stimulation, Tregs may exhibit plasticity toward a proinflammatory phenotype, producing interleukin 17 (IL-17) and/or interferon γ (IFN-γ). Such deregulation of Tregs may contribute to the perpetuation of inflammatory processes, including graft-versus-host disease. Thus, it is important to identify immunomodulatory factors influencing Treg stability. Platelet-derived microparticles (PMPs) are involved in hemostasis and vascular health and have recently been shown to be intimately involved in (pathogenic) immune responses. Therefore, we investigated whether PMPs have the ability to affect Treg plasticity. PMPs were cocultured with healthy donor peripheral blood-derived Tregs that were stimulated with anti-CD3/CD28 monoclonal antibodies in the presence of IL-2, IL-15, and IL-1β. PMPs prevented the differentiation of peripheral blood-derived Tregs into IL-17- and IFN-γ-producing cells, even in the presence of the IL-17-driving proinflammatory cytokine IL-1β. The mechanism of action by which PMPs prevent Treg plasticity consisted of rapid and selective P-selectin-dependent binding of PMPs to a CCR6(+)HLA-DR(+)memory-like Treg subset and their ability to inhibit Treg proliferation, in part through CXCR3 engagement. The findings that ~8% of Tregs in the circulation of healthy individuals are CD41(+)P-selectin(+)and that distinct binding of patient plasma PMPs to Tregs was observed support in vivo relevance. These findings open the exciting possibility that PMPs actively regulate the immune response at sites of (vascular) inflammation, where they are known to accumulate and interact with leukocytes, consolidating the (vascular) healing process.

  16. Repeated supra-maximal sprint cycling with and without sodium bicarbonate supplementation induces endothelial microparticle release.

    PubMed

    Kirk, Richard J; Peart, Daniel J; Madden, Leigh A; Vince, Rebecca V

    2014-01-01

    Under normal homeostatic conditions, the endothelium releases microparticles (MPs), which are known to increase under stressful conditions and in disease states. CD105 (endoglin) and CD106 (vascular cell adhesion molecule-1) are expressed on the surface of endothelial cells and increased expression in response to stress may be observed. A randomised-controlled double-blinded study aimed to examine the use of endothelial MPs as a marker for the state of one's endothelium, as well as whether maintaining acid-base homeostasis affects the release of these MPs. This study tested seven healthy male volunteers, who completed a strenuous cycling protocol, with venous blood analysed for CD105+ and CD106+ MPs by flow cytometry at regular intervals. Prior to each trial participants consumed either 0.3 g·kg(-1) body mass of sodium bicarbonate (NaHCO3), or 0.045 g·kg(-1) body mass of sodium chloride (NaCl). A significant rise in endothelial CD105+ MPs and CD106+ MPs (p<0.05) was observed at 90 min post-exercise. A significant trend was shown for these MPs to return to resting levels 180 min post-exercise in both groups. No significance was found between experimental groups, suggesting that maintaining acid-base variables closer to basal levels has little effect upon the endothelial stress response for this particular exercise mode. In conclusion, strenuous exercise is accompanied by MP release and the endothelium is able to rapidly recover in healthy individuals, whilst maintaining acid-base homeostasis does not attenuate the MP release from the endothelium after exercise.

  17. Global deposition of airborne dioxin.

    PubMed

    Booth, Shawn; Hui, Joe; Alojado, Zoraida; Lam, Vicky; Cheung, William; Zeller, Dirk; Steyn, Douw; Pauly, Daniel

    2013-10-15

    We present a global dioxin model that simulates one year of atmospheric emissions, transport processes, and depositions to the earth's terrestrial and marine habitats. We map starting emission levels for each land area, and we also map the resulting deposits to terrestrial and marine environments. This model confirms that 'hot spots' of deposition are likely to be in northern Europe, eastern North America, and in parts of Asia with the highest marine dioxin depositions being the northeast and northwest Atlantic, western Pacific, northern Indian Ocean and the Mediterranean. It also reveals that approximately 40% of airborne dioxin emissions are deposited to marine environments and that many countries in Africa receive more dioxin than they produce, which results in these countries being disproportionately impacted. Since human exposure to dioxin is largely through diet, this work highlights food producing areas that receive higher atmospheric deposits of dioxin than others.

  18. The Sandia Airborne Computer (SANDAC)

    SciTech Connect

    Nava, E.J.

    1992-06-01

    The Sandia Airborne Computer (SANDAC) is a small, modular, high performance, multiprocessor computer originally designed for aerospace applications. It can use a combination of Motorola 68020 and 68040 based processor modules along with AT&T DSP32C based signal processing modules. The system is designed to use up to 15 processors in almost any combination and a complete system can include up to 20 modules. Depending on the mix of processors, total computational throughput can range from 2.5 to greater than 225 Million Instructions Per Second (MIPS). The system is designed so that processors can access all resources in the machine and the inter-processor communication details are completely transparent to the software. In addition to processors, the system includes input/output, memory, and special function modules. Because of its ease of use, small size, durability, and configuration flexibility, SANDAC has been used on applications ranging from missile navigation, guidance, and control systems to medical imaging systems.

  19. Modis-N airborne simulator

    NASA Technical Reports Server (NTRS)

    Cech, Steven D.

    1992-01-01

    All required work associated with the above referenced contract has been successfully completed at this time. The Modis-N Airborne Simulator has been developed from existing AB184 Wildfire spectrometer parts as well as new detector arrays, optical components, and associated mechanical and electrical hardware. The various instrument components have been integrated into an operational system which has undergone extensive laboratory calibration and testing. The instrument has been delivered to NASA Ames where it will be installed on the NASA ER-2. The following paragraphs detail the specific tasks performed during the contract effort, the results obtained during the integration and testing of the instrument, and the conclusions which can be drawn from this effort.

  20. In vitro degradation behavior of chitosan based hybrid microparticles.

    PubMed

    Jayasuriya, A Champa; Mauch, Kristalyn J

    2011-05-17

    The degradation properties of the MPs is important to the long-term benefits of the use of the chitosan (CS) based hybrid MPs in bone tissue-engineering, because the degradation kinetics could affect a multitude of processes within the cell, such as cell growth, tissue regeneration, and host response. The aim of this study was to investigate the degradation of solid, hybrid CS microparticles (MPs), CS-10% calcium phosphate (CaHPO4, w/w), and CS-10% calcium carbonate (CaCO3, w/w) MPs in phosphate buffered solution (PBS) over a 30-week period. The hybrid MPs were synthesized by emulsification technique, cross-linked with 64% sodium tripolyphosphate (TPP), purified and air dried overnight. Each sample had 30 mg of MPs was placed in a glass vial with 9 ml of PBS added and then the vial was closed to prevent evaporation. Every week 4 ml of the incubated solution was removed for sample measurement and all samples were replaced with an equivalent amount of fresh medium. The samples were maintained at 37°C under continuous shaking. The hybrid MPs were measured for pH and calcium release, every week in triplicate. At 0, 5, 10, 15, 20, 25, and 30 weeks, surface and bulk morphology were analyzed with a scanning electron microscope (SEM). The degradation data suggested that the hybrid MPs were stable at least up to 25 week and maintain the physiologically relevant pH. Therefore, we can use these hybrid MPs to apply in the bone tissue engineering applications since they do not degrade within a short period. PMID:25289115

  1. Platelet microparticles in immune thrombocytopenic purpura in pediatrics.

    PubMed

    Tantawy, Azza A G; Matter, Randa M; Hamed, Ahmed A; Shams El Din El Telbany, Manal A

    2010-05-01

    Immune thrombocytopenic purpura (ITP) is one of the most common hemorrhagic disorders in childhood. Platelet microparticles (PMPs) arise with platelet activation with procoagulant activity. Elevated PMP levels in adult ITP were reported to be thrombogenic in certain settings. However, their clinical significance in pediatric ITP was not studied. The aims of this study were to assess PMP levels in ITP in children and adolescents, and its correlation with clinical status and bleeding score. The study included 40 ITP patients (20 acute aged 9 +/- 2.19 years and 20 chronic aged 10.8 +/- 4.7 years) randomly selected from the Hematology Clinic, Children's Hospital, Ain Shams University, Cairo, Egypt, and 30 sex- and age-matched healthy controls aged 9 +/- 3.28 years. Patients were subjected to detailed history, assessment of bleeding score, complete hemogram, cytological bone marrow examination, and PMP quantification in peripheral blood by flow cytometry. Acute ITP patients had significant increase in PMPs, PMP/platelet count, and PMP percent compared to controls (P = .002, P < .0001, P < .0001, respectively) and compared to chronic ITP patients (P < .0001, P < .0001, P < .0001, respectively). PMPs were significantly decreased in chronic ITP patients compared to controls (P = .001), but PMP/platelet and PMP percent showed highly significant increase in chronic ITP (P < .0001). No correlation was evident between PMP levels and platelet count in either group (P > .05). Neither higher bleeding score nor thrombotic manifestations were observed in the studied ITP patients with high PMP levels. Elevated PMP levels may be protective against severe bleeding events in pediatric ITP. The role of PMP studies in deciding the management plan of childhood and adolescent ITP needs further evaluation.

  2. Platelet microparticles reprogram macrophage gene expression and function.

    PubMed

    Laffont, Benoit; Corduan, Aurélie; Rousseau, Matthieu; Duchez, Anne-Claire; Lee, Chan Ho C; Boilard, Eric; Provost, Patrick

    2016-01-01

    Platelet microparticles (MPs) represent the most abundant MPs subtype in the circulation, and can mediate intercellular communication through delivery of bioactives molecules, such as cytokines, proteins, lipids and RNAs. Here, we show that platelet MPs can be internalised by primary human macrophages and deliver functional miR-126-3p. The increase in macrophage miR-126-3p levels was not prevented by actinomycin D, suggesting that it was not due to de novo gene transcription. Platelet MPs dose-dependently downregulated expression of four predicted mRNA targets of miR-126-3p, two of which were confirmed also at the protein level. The mRNA downregulatory effects of platelet MPs were abrogated by expression of a neutralising miR-126-3p sponge, implying the involvement of miR-126-3p. Transcriptome-wide, microarray analyses revealed that as many as 66 microRNAs and 653 additional RNAs were significantly and differentially expressed in macrophages upon exposure to platelet MPs. More specifically, platelet MPs induced an upregulation of 34 microRNAs and a concomitant downregulation of 367 RNAs, including mRNAs encoding for cytokines/chemokines CCL4, CSF1 and TNF. These changes were associated with reduced CCL4, CSF1 and TNF cytokine/chemokine release by macrophages, and accompanied by a marked increase in their phagocytic capacity. These findings demonstrate that platelet MPs can modify the transcriptome of macrophages, and reprogram their function towards a phagocytic phenotype. PMID:26333874

  3. Hyperphosphatemia, Phosphoprotein Phosphatases, and Microparticle Release in Vascular Endothelial Cells

    PubMed Central

    Abbasian, Nima; Burton, James O.; Herbert, Karl E.; Tregunna, Barbara-Emily; Brown, Jeremy R.; Ghaderi-Najafabadi, Maryam; Brunskill, Nigel J.; Goodall, Alison H.

    2015-01-01

    Hyperphosphatemia in patients with advanced CKD is thought to be an important contributor to cardiovascular risk, in part because of endothelial cell (EC) dysfunction induced by inorganic phosphate (Pi). Such patients also have an elevated circulating concentration of procoagulant endothelial microparticles (MPs), leading to a prothrombotic state, which may contribute to acute occlusive events. We hypothesized that hyperphosphatemia leads to MP formation from ECs through an elevation of intracellular Pi concentration, which directly inhibits phosphoprotein phosphatases, triggering a global increase in phosphorylation and cytoskeletal changes. In cultured human ECs (EAhy926), incubation with elevated extracellular Pi (2.5 mM) led to a rise in intracellular Pi concentration within 90 minutes. This was mediated by PiT1/slc20a1 Pi transporters and led to global accumulation of tyrosine- and serine/threonine-phosphorylated proteins, a marked increase in cellular Tropomyosin-3, plasma membrane blebbing, and release of 0.1- to 1-μm-diameter MPs. The effect of Pi was independent of oxidative stress or apoptosis. Similarly, global inhibition of phosphoprotein phosphatases with orthovanadate or fluoride yielded a global protein phosphorylation response and rapid release of MPs. The Pi-induced MPs expressed VE-cadherin and superficial phosphatidylserine, and in a thrombin generation assay, they displayed significantly more procoagulant activity than particles derived from cells incubated in medium with a physiologic level of Pi (1 mM). These data show a mechanism of Pi-induced cellular stress and signaling, which may be widely applicable in mammalian cells, and in ECs, it provides a novel pathologic link between hyperphosphatemia, generation of MPs, and thrombotic risk. PMID:25745026

  4. Hyperphosphatemia, Phosphoprotein Phosphatases, and Microparticle Release in Vascular Endothelial Cells.

    PubMed

    Abbasian, Nima; Burton, James O; Herbert, Karl E; Tregunna, Barbara-Emily; Brown, Jeremy R; Ghaderi-Najafabadi, Maryam; Brunskill, Nigel J; Goodall, Alison H; Bevington, Alan

    2015-09-01

    Hyperphosphatemia in patients with advanced CKD is thought to be an important contributor to cardiovascular risk, in part because of endothelial cell (EC) dysfunction induced by inorganic phosphate (Pi). Such patients also have an elevated circulating concentration of procoagulant endothelial microparticles (MPs), leading to a prothrombotic state, which may contribute to acute occlusive events. We hypothesized that hyperphosphatemia leads to MP formation from ECs through an elevation of intracellular Pi concentration, which directly inhibits phosphoprotein phosphatases, triggering a global increase in phosphorylation and cytoskeletal changes. In cultured human ECs (EAhy926), incubation with elevated extracellular Pi (2.5 mM) led to a rise in intracellular Pi concentration within 90 minutes. This was mediated by PiT1/slc20a1 Pi transporters and led to global accumulation of tyrosine- and serine/threonine-phosphorylated proteins, a marked increase in cellular Tropomyosin-3, plasma membrane blebbing, and release of 0.1- to 1-μm-diameter MPs. The effect of Pi was independent of oxidative stress or apoptosis. Similarly, global inhibition of phosphoprotein phosphatases with orthovanadate or fluoride yielded a global protein phosphorylation response and rapid release of MPs. The Pi-induced MPs expressed VE-cadherin and superficial phosphatidylserine, and in a thrombin generation assay, they displayed significantly more procoagulant activity than particles derived from cells incubated in medium with a physiologic level of Pi (1 mM). These data show a mechanism of Pi-induced cellular stress and signaling, which may be widely applicable in mammalian cells, and in ECs, it provides a novel pathologic link between hyperphosphatemia, generation of MPs, and thrombotic risk. PMID:25745026

  5. Association of microparticles and neutrophil activation with decompression sickness.

    PubMed

    Thom, Stephen R; Bennett, Michael; Banham, Neil D; Chin, Walter; Blake, Denise F; Rosen, Anders; Pollock, Neal W; Madden, Dennis; Barak, Otto; Marroni, Alessandro; Balestra, Costantino; Germonpre, Peter; Pieri, Massimo; Cialoni, Danilo; Le, Phi-Nga Jeannie; Logue, Christopher; Lambert, David; Hardy, Kevin R; Sward, Douglas; Yang, Ming; Bhopale, Veena B; Dujic, Zeljko

    2015-09-01

    Decompression sickness (DCS) is a systemic disorder, assumed due to gas bubbles, but additional factors are likely to play a role. Circulating microparticles (MPs)--vesicular structures with diameters of 0.1-1.0 μm--have been implicated, but data in human divers have been lacking. We hypothesized that the number of blood-borne, Annexin V-positive MPs and neutrophil activation, assessed as surface MPO staining, would differ between self-contained underwater breathing-apparatus divers suffering from DCS vs. asymptomatic divers. Blood was analyzed from 280 divers who had been exposed to maximum depths from 7 to 105 meters; 185 were control/asymptomatic divers, and 90 were diagnosed with DCS. Elevations of MPs and neutrophil activation occurred in all divers but normalized within 24 h in those who were asymptomatic. MPs, bearing the following proteins: CD66b, CD41, CD31, CD142, CD235, and von Willebrand factor, were between 2.4- and 11.7-fold higher in blood from divers with DCS vs. asymptomatic divers, matched for time of sample acquisition, maximum diving depth, and breathing gas. Multiple logistic regression analysis documented significant associations (P < 0.001) between DCS and MPs and for neutrophil MPO staining. Effect estimates were not altered by gender, body mass index, use of nonsteroidal anti-inflammatory agents, or emergency oxygen treatment and were modestly influenced by divers' age, choice of breathing gas during diving, maximum diving depth, and whether repetitive diving had been performed. There were no significant associations between DCS and number of MPs without surface proteins listed above. We conclude that MP production and neutrophil activation exhibit strong associations with DCS.

  6. A continuous DC-insulator dielectrophoretic sorter of microparticles.

    PubMed

    Srivastava, Soumya Keshavamurthy; Baylon-Cardiel, Javier L; Lapizco-Encinas, Blanca H; Minerick, Adrienne Robyn

    2011-04-01

    A lab-on-a-chip device is described for continuous sorting of fluorescent polystyrene microparticles utilizing direct current insulating dielectrophoresis (DC-iDEP) at lower voltages than previously reported. Particles were sorted by combining electrokinetics and dielectrophoresis in a 250 μm wide PDMS microchannel containing a rectangular insulating obstacle and four outlet channels. The DC-iDEP particle flow behaviors were investigated with 3.18, 6.20 and 10 μm fluorescent polystyrene particles which experience negative DEP forces depending on particle size, DC electric field magnitude and medium conductivity. Due to negative DEP effects, particles are deflected into different outlet streams as they pass the region of high electric field density around the obstacle. Particles suspended in dextrose added phosphate buffer saline (PBS) at conductivities ranging from 0.50 to 8.50 mS/cm at pH 7.0 were compared at 6.85 and 17.1V/cm. Simulations of electrokinetic and dielectrophoretic forces were conducted with COMSOL Multiphysics® to predict particle pathlines. Experimental and simulation results show the effect of medium and voltage operating conditions on particle sorting. Further, smaller particles experience smaller iDEP forces and are more susceptible to competing nonlinear electrostatic effects, whereas larger particles experience greater iDEP forces and prefer channels 1 and 2. This work demonstrates that 6.20 and 10 μm particles can be independently sorted into specific outlet streams by tuning medium conductivity even at low operating voltages. This work is an essential step forward in employing DC-iDEP for multiparticle sorting in a continuous flow, multiple outlet lab-on-a-chip device. PMID:21338990

  7. In vitro degradation behavior of chitosan based hybrid microparticles

    PubMed Central

    Jayasuriya, A. Champa; Mauch, Kristalyn J.

    2014-01-01

    The degradation properties of the MPs is important to the long-term benefits of the use of the chitosan (CS) based hybrid MPs in bone tissue-engineering, because the degradation kinetics could affect a multitude of processes within the cell, such as cell growth, tissue regeneration, and host response. The aim of this study was to investigate the degradation of solid, hybrid CS microparticles (MPs), CS-10% calcium phosphate (CaHPO4, w/w), and CS-10% calcium carbonate (CaCO3, w/w) MPs in phosphate buffered solution (PBS) over a 30-week period. The hybrid MPs were synthesized by emulsification technique, cross-linked with 64% sodium tripolyphosphate (TPP), purified and air dried overnight. Each sample had 30 mg of MPs was placed in a glass vial with 9 ml of PBS added and then the vial was closed to prevent evaporation. Every week 4 ml of the incubated solution was removed for sample measurement and all samples were replaced with an equivalent amount of fresh medium. The samples were maintained at 37°C under continuous shaking. The hybrid MPs were measured for pH and calcium release, every week in triplicate. At 0, 5, 10, 15, 20, 25, and 30 weeks, surface and bulk morphology were analyzed with a scanning electron microscope (SEM). The degradation data suggested that the hybrid MPs were stable at least up to 25 week and maintain the physiologically relevant pH. Therefore, we can use these hybrid MPs to apply in the bone tissue engineering applications since they do not degrade within a short period. PMID:25289115

  8. Freshwater and marine microalgae harvesting with magnetic microparticles

    NASA Astrophysics Data System (ADS)

    Vergini, Sofia; Aravantinou, Andriana; Manariotis, Ioannis D.

    2014-05-01

    Microalgae are considered to be the most promising new source of biomass and biofuels. The use of microalgae for sustainable biofuel production is important because of the lack of hydrocarbons sources. Many studies have focused on the recovery of microalgae biomass from the growth medium in order to reduce production cost. Alternative technologies, other than conventional methods (i.e. centrifugation, coagulation-flocculation, filtration and screening, gravity sedimentation, and flotation), capable to process large volumes of microalgae cultures at a low cost, are essential for microalgae biomass production. The aim of this study was to investigate the harvesting of microalgae cells using magnetic materials (magnetic activated carbon, magnetite microparticles) compared to common flocculants (FeCl3·6H2O, AlCl3, Al2(SO4)3·18H2O), and gravity sedimentation. Scenedesmus rubescens and Dunaliella tertiolecta were selected as representative for freshwater and marine microalgae, respectively. The cultivation of microalgae was conducted under continuous artificial light, in 10 L and 20 L flasks. Samples were taken at different operation intervals to conduct harvesting studies. Batch experiments were conducted to investigate the effect of sorption of microalgae on the magnetic material. The experimental data in the presence of magnetic material were adequately described by the Langmuir isotherm. Scenedesmus rubescens was better adsorbed and harvested than Dunaliella tertiolecta. Furthermore, the recovery of microalgae biomass was greater in cultures with high cell concentration compared to cultures with low concentrations. The results of the jar-test experiments showed that the AlCl3 was more effective than the other two flocculants tested. Specifically, the harvesting efficiency was up to 99% for both microalgae species. Gravity sedimentation was tested for 1 h in both species, and better sedimentation efficiency was observed with the Scenedesmus rubescens.

  9. Structured microparticles with tailored properties produced by membrane emulsification.

    PubMed

    Vladisavljević, Goran T

    2015-11-01

    This paper provides an overview of membrane emulsification routes for fabrication of structured microparticles with tailored properties for specific applications. Direct (bottom-up) and premix (top-down) membrane emulsification processes are discussed including operational, formulation and membrane factors that control the droplet size and droplet generation regimes. A special emphasis was put on different methods of controlled shear generation on membrane surface, such as cross flow on the membrane surface, swirl flow, forward and backward flow pulsations in the continuous phase and membrane oscillations and rotations. Droplets produced by membrane emulsification can be used for synthesis of particles with versatile morphology (solid and hollow, matrix and core/shell, spherical and non-spherical, porous and coherent, composite and homogeneous), which can be surface functionalised and coated or loaded with macromolecules, nanoparticles, quantum dots, drugs, phase change materials and high molecular weight gases to achieve controlled/targeted drug release and impart special optical, chemical, electrical, acoustic, thermal and magnetic properties. The template emulsions including metal-in-oil, solid-in-oil-in-water, oil-in-oil, multilayer, and Pickering emulsions can be produced with high encapsulation efficiency of encapsulated materials and narrow size distribution and transformed into structured particles using a variety of solidification processes, such as polymerisation (suspension, mini-emulsion, interfacial and in-situ), ionic gelation, chemical crosslinking, melt solidification, internal phase separation, layer-by-layer electrostatic deposition, particle self-assembly, complex coacervation, spray drying, sol-gel processing, and molecular imprinting. Particles fabricated from droplets produced by membrane emulsification include nanoclusters, colloidosomes, carbon aerogel particles, nanoshells, polymeric (molecularly imprinted, hypercrosslinked, Janus and core

  10. Inhalable DNase I microparticles engineered with biologically active excipients.

    PubMed

    Osman, Rihab; Al Jamal, Khuloud T; Kan, Pei-Lee; Awad, Gehanne; Mortada, Nahed; El-Shamy, Abd-Elhameed; Alpar, Oya

    2013-12-01

    Highly viscous mucus poses a big challenge for the delivery of particulates carrying therapeutics to patients with cystic fibrosis. In this study, surface modifying DNase I loaded particles using different excipients to achieve better lung deposition, higher enzyme stability or better biological activity had been exploited. For the purpose, controlled release microparticles (MP) were prepared by co-spray drying DNase I with the polymer poly-lactic-co-glycolic acid (PLGA) and the biocompatible lipid surfactant 1,2-dipalmitoyl-Sn-phosphatidyl choline (DPPC) using various hydrophilic excipients. The effect of the included modifiers on the particle morphology, size, zeta potential as well as enzyme encapsulation efficiency, biological activity and release had been evaluated. Powder aerosolisation performance and particle phagocytosis by murine macrophages were also investigated. The results showed that more than 80% of enzyme activity was recovered after MP preparation and that selected surface modifiers greatly increased the enzyme encapsulation efficiency. The particle morphology was greatly modified altering in turn the powders inhalation indices where dextran, ovalbumin and chitosan hydrochloride increased considerably the respirable fraction compared to the normal hydrophilic carriers lactose and PVP. Despite of the improved aerosolisation caused by chitosan hydrochloride, yet retardation of chitosan coated particles in artificial mucus samples discouraged its application. On the other hand, dextran and polyanions enhanced DNase I effect in reducing cystic fibrosis mucus viscosity. DPPC proved good ability to reduce particles phagocytic uptake even in the presence of the selected adjuvants. The prepared MP systems were biocompatible with lung epithelial cells. To conclude, controlled release DNase I loaded PLGA-MP with high inhalation indices and enhanced mucolytic activity on CF sputum could be obtained by surface modifying the particles with PGA or dextran. PMID

  11. Physical and electrochemical study of cobalt oxide nano- and microparticles

    SciTech Connect

    Alburquenque, D.; Vargas, E.; Denardin, J.C.; Escrig, J.; Marco, J.F.; Gautier, J.L.

    2014-07-01

    Cobalt oxide nanocrystals of size 17–21 nm were synthesized by a simple reaction between cobalt acetate (II) and dodecylamine. On the other hand, micrometric Co{sub 3}O{sub 4} was prepared using the ceramic method. The structural examination of these materials was performed using powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and transmission electron microscopy (TEM and HRTEM). XRD studies showed that the oxides were pure, well-crystallized, spinel cubic phases with a-cell parameter of 0.8049 nm and 0.8069 nm for the nano and micro-oxide, respectively. The average particle size was 19 nm (nano-oxide) and 1250 μm (micro-oxide). Morphological studies carried out by SEM and TEM analyses have shown the presence of octahedral particles in both cases. Bulk and surface properties investigated by X-ray photoelectron spectroscopy (XPS), point zero charge (pzc), FTIR and cyclic voltammetry indicated that there were no significant differences in the composition on both materials. The magnetic behavior of the samples was determined using a vibrating sample magnetometer. The compounds showed paramagnetic character and no coercivity and remanence in all cases. Galvanostatic measurements of electrodes formed with nanocrystals showed better performance than those built with micrometric particles. - Highlights: • Spinel Co{sub 3}O{sub 4} nanoparticles and microparticles with same structure but with different cell parameters, particle size and surface area were synthesized. • Oxide nanoparticles showed better electrochemical behavior than micrometric ones due to area effect.

  12. Microparticle shape effects on margination, near-wall dynamics and adhesion in a three-dimensional simulation of red blood cell suspension.

    PubMed

    Vahidkhah, Koohyar; Bagchi, Prosenjit

    2015-03-21

    We present a 3D computational modeling study of the transport of micro-scale drug carriers modeled as microparticles of different shapes (spherical, oblate, and prolate) in whole blood represented as a suspension of deformable red blood cells. The objective is to quantify the effect of microparticle shapes on their margination, near-wall dynamics and adhesion. We observe that the near-wall accumulation is highest for oblate particles of moderate aspect ratio, followed by spherical particles, and lowest for very elongated prolate particles. The result is explained using micro-scale dynamics of individual particles, and their interaction with red blood cells. We observe that the orientation of microparticles in 3D space and the frequency of their collisions with red blood cells are the key factors affecting their margination. We show that due to repeated collisions with red blood cells in the presence of a bounding wall, the axes of revolution of oblate particles align near the plane of the shear flow, but those of prolate particles shift towards the vorticity axis with a wider distribution. Such specific orientations lead to more frequent collisions and a greater lateral drift for oblate particles than microspheres, but less frequent collisions and a reduced lateral drift for elongated prolate particles, resulting in the observed differences in their near-wall accumulation. Once marginated, the particle shape has an entirely different effect on the likelihood of making particle-wall contacts. We find that marginated prolate particles, due to their alignment along the vorticity axis and large angular fluctuations, are more likely to make contacts with the wall than spherical and oblate particles. We further simulate the adhesion between flowing microparticles and the wall in the presence of red blood cells, and observe that once wall contacts are established, the likelihood of firm adhesion is greater for disk-like particles, followed by elongated prolates, and

  13. Airborne thermography or infrared remote sensing.

    PubMed

    Goillot, C C

    1975-01-01

    Airborne thermography is part of the more general remote sensing activity. The instruments suitable for image display are infrared line scanners. A great deal of interest has developed during the past 10 years in airborne thermal remote sensing and many applications are in progress. Infrared scanners on board a satellite are used for observation of cloud cover; airborne infrared scanners are used for forest fire detection, heat budget of soils, detecting insect attack, diseases, air pollution damage, water stress, salinity stress on vegetation, only to cite some main applications relevant to agronomy. Using this system it has become possible to get a 'picture' of our thermal environment.

  14. Microparticles of Aloe vera/vitamin E/chitosan: microscopic, a nuclear imaging and an in vivo test analysis for burn treatment.

    PubMed

    Pereira, Gabriela Garrastazu; Santos-Oliveira, Ralph; Albernaz, Martha S; Canema, Daniel; Weismüller, Gilberto; Barros, Eduardo Bede; Magalhães, Luciana; Lima-Ribeiro, Maria Helena Madruga; Pohlmann, Adriana Raffin; Guterres, Silvia S

    2014-02-01

    The use of drug-loaded nanoparticles and microparticles has been increasing, especially for cosmetic and drug delivery purposes. In this work, a new microparticle formulation was developed for use in the healing process of skin burns in a composition of Aloe vera/vitamin E/chitosan. In order to observe the morphological properties, Raman and atomic force microscopy evaluation were performed. The biodistribution studies were analyzed by using a nuclear methodology, labeling the microparticles with Technetium-99m and in vivo test was procedure to analyzed the cicatrization process. The results of AFM analysis show the formation and the adherence property of the microparticles. Raman analyses show the distribution of each component in the microparticle. The nuclear method used shows that the biodistribution of the microparticles remained in the skin. The in vivo cicatrization test showed that the poloxamer gel containing the microparticles make a better cicatrization in relation to the other formulations tested.

  15. Spacecraft Maximum Allowable Concentrations for Airborne Contaminants

    NASA Technical Reports Server (NTRS)

    James, John T.

    2008-01-01

    The enclosed table lists official spacecraft maximum allowable concentrations (SMACs), which are guideline values set by the NASA/JSC Toxicology Group in cooperation with the National Research Council Committee on Toxicology (NRCCOT). These values should not be used for situations other than human space flight without careful consideration of the criteria used to set each value. The SMACs take into account a number of unique factors such as the effect of space-flight stress on human physiology, the uniform good health of the astronauts, and the absence of pregnant or very young individuals. Documentation of the values is given in a 5 volume series of books entitled "Spacecraft Maximum Allowable Concentrations for Selected Airborne Contaminants" published by the National Academy Press, Washington, D.C. These books can be viewed electronically at http://books.nap.edu/openbook.php?record_id=9786&page=3. Short-term (1 and 24 hour) SMACs are set to manage accidental releases aboard a spacecraft and permit risk of minor, reversible effects such as mild mucosal irritation. In contrast, the long-term SMACs are set to fully protect healthy crewmembers from adverse effects resulting from continuous exposure to specific air pollutants for up to 1000 days. Crewmembers with allergies or unusual sensitivity to trace pollutants may not be afforded complete protection, even when long-term SMACs are not exceeded. Crewmember exposures involve a mixture of contaminants, each at a specific concentration (C(sub n)). These contaminants could interact to elicit symptoms of toxicity even though individual contaminants do not exceed their respective SMACs. The air quality is considered acceptable when the toxicity index (T(sub grp)) for each toxicological group of compounds is less than 1, where T(sub grp), is calculated as follows: T(sub grp) = C(sub 1)/SMAC(sub 1) + C(sub 2/SMAC(sub 2) + ...+C(sub n)/SMAC(sub n).

  16. Formulation and characterization of atropine sulfate in albumin-chitosan microparticles for in vivo ocular drug delivery.

    PubMed

    Addo, Richard T; Yeboah, Kwame G; Siwale, Rodney C; Siddig, Aladin; Jones, Alphia; Ubale, Ruhi V; Akande, Janet; Nettey, Henry; Patel, Neil J; Addo, Evelyn; D'Souza, Martin J

    2015-05-01

    The overall study goal was to produce a microparticle formulation containing atropine sulfate for ocular administration with improved efficacy and lower side effects, compared with that of the standard marketed atropine solution. The objective was to prepare an atropine sulfate-loaded bovine serum albumin-chitosan microparticle that would have longer contact time on the eyes as well as better mydriatic and cycloplegic effect using a rabbit model. The microparticle formulation was prepared by method of spray-drying technique. The percent drug loading and encapsulation efficiency were assessed using a USP (I) dissolution apparatus. The particle sizes and zeta potential were determined using laser scattering technique and the surface morphology of the microparticles was determined using a scanning electron microscope. The product yield was calculated from relative amount of material used. In vitro cytotoxicity and uptake by human corneal epithelial cells were examined using AlamarBlue and confocal microscopy. The effects of the microparticle formulation on mydriasis in comparison with the marketed atropine sulfate solution were evaluated in rabbit eyes. The prepared microparticle formulation had ideal physicochemical characteristics for delivery into the eyes. The in vivo studies showed that the microparticles had superior effects on mydriasis in rabbits than the marketed solutions

  17. Development of Suppositories Containing Flutamide-Loaded Alginate-Tamarind Microparticles for Rectal Administration: In Vitro and in Vivo Studies.

    PubMed

    Patil, Bharati Shivajirao; Mahajan, Hitendra Shaligram; Surana, Sanjay Javerilal

    2015-01-01

    In the present work the absorption of flutamide from suppositories containing hydrophilic tamarind alginate microparticles after rectal administration in rats was investigated with the purpose of enhancing bioavailability and to avoid hepatic toxicity. Microparticles were developed by ionic gelation method and optimized using one factorial design of response surface methodology. The optimized batch of microparticles had tamarind gum-sodium alginate (1 : 3) ratio and showed entrapment efficiency 94.969% and mucoadhesion strength 94.646% with desirability of 0.961. Suppositories loaded with microparticles were developed by fusion method using poloxamer 407 and poloxamer 188 in combination as suppository base. Kinetic analysis of the release data of microparticle-loaded suppositories showed time-independent release of drug. Higher values of 'n' (>0.89) represent Super Case II-type drug release. The pharmacokinetics of flutamide from flutamide tamarind alginate microparticle-loaded suppository were compared with oral suspension. Cmax of microparticle-loaded suppository was significantly larger than that of oral suspension (1.711 and 0.859 µg/mL, respectively). PMID:26521849

  18. Diffusion loading and drug delivery characteristics of alginate gel microparticles produced by a novel impinging aerosols method.

    PubMed

    Hariyadi, Dewi M; Lin, Sharon Chien-Yu; Wang, Yiwei; Bostrom, Thor; Turner, Mark S; Bhandari, Bhesh; Coombes, Allan G A

    2010-12-01

    Microencapsulation of a hydrophilic active (gentamicin sulphate (GS)) and a hydrophobic non-steroidal anti-inflammatory drug (ibuprofen) in alginate gel microparticles was accomplished by molecular diffusion of the drug species into microparticles produced by impinging aerosols of alginate solution and CaCl(2) cross-linking solution. A mean particle size in the range of 30-50 µm was measured using laser light scattering and high drug loadings of around 35 and 29% weight/dry microparticle weight were obtained for GS and ibuprofen respectively. GS release was similar in simulated intestinal fluid (phosphate buffer saline (PBS), pH 7.4, 37°C) and simulated gastric fluid (SGF) (HCl, pH 1.2, 37°C) but was accelerated in PBS following incubation of microparticles in HCl. Ibuprofen release was restricted in SGF but occurred freely on transfer of microparticles into PBS with almost 100% efficiency. GS released in PBS over 7 h, following incubation of microparticles in HCl for 2 h was found to retain at least 80% activity against Staphylococcus epidermidis while Ibuprofen retained around 50% activity against Candida albicans. The impinging aerosols technique shows potential for producing alginate gel microparticles of utility for protection and controlled delivery of a range of therapeutic molecules.

  19. Enhanced Biological Functions of Human Mesenchymal Stem-Cell Aggregates Incorporating E-Cadherin-Modified PLGA Microparticles.

    PubMed

    Zhang, Yan; Mao, Hongli; Gao, Chao; Li, Suhua; Shuai, Qizhi; Xu, Jianbin; Xu, Ke; Cao, Lei; Lang, Ren; Gu, Zhongwei; Akaike, Toshihiro; Yang, Jun

    2016-08-01

    Mesenchymal stem cells (MSCs) have emerged as a promising source of multipotent cells for various cell-based therapies due to their unique properties, and formation of 3D MSC aggregates has been explored as a potential strategy to enhance therapeutic efficacy. In this study, poly(lactic-co-glycolic acid) (PLGA) microparticles modified with human E-cadherin fusion protein (hE-cad-PLGA microparticles) have been fabricated and integrated with human MSCs to form 3D cell aggregates. The results show that, compared with the plain PLGA, the hE-cad-PLGA microparticles distribute within the aggregates more evenly and further result in a more significant improvement of cellular proliferation and secretion of a series of bioactive factors due to the synergistic effects from the bioactive E-cadherin fragments and the PLGA microparticles. Meanwhile, the hE-cad-PLGA microparticles incorporated in the aggregates upregulate the phosphorylation of epidermal growth factor receptors and activate the AKT and ERK1/2 signaling pathways in the MSCs. Additionally, the E-cadherin/β-catenin cellular membrane complex in the MSCs is markedly stimulated by the hE-cad-PLGA microparticles. Therefore, engineering 3D cell aggregates with hE-cad-PLGA microparticles can be a promising method for ex vivo multipotent stem-cell expansion with enhanced biological functions and may offer a novel route to expand multipotent stem-cell-based clinical applications. PMID:27245478

  20. Cetirizine dihydrochloride loaded microparticles design using ionotropic cross-linked chitosan nanoparticles by spray-drying method.

    PubMed

    Li, Feng-Qian; Ji, Rui-Rui; Chen, Xu; You, Ben-Ming; Pan, Yong-Hua; Su, Jia-Can

    2010-12-01

    To control the release rate and mask the bitter taste, cetirizine dihydrochloride (CedH) was entrapped within chitosan nanoparticles (CS-NPs) using an ionotropic gelation process, followed by microencapsulation to produce CS matrix microparticles using a spray-drying method. The aqueous colloidal CS-NPs dispersions with a drug encapsulation efficiency (EE) of <15%, were then spray dried to produce a powdered nanoparticles-in-microparticles system with an EE of >70%. The resultant spherical CS microparticles had a smooth surface, were free of organic solvent residue and showed a diameter range of 0.5~5 μm. The in vitro drug release properties of CedH encapsulated microparticles showed an initial burst effect during the first 2 h. Drug release from the matrix CS microparticles could be retarded by the crosslinking agent pentasodium tripolyphosphate or the wall material. The technique of 'ionotropic gelation' combined with 'spray-drying' could be applicable for preparation of CS nanoparticlesin-microparticles drug delivery systems. CS-NPs based microparticles might provide a potential micro-carrier for oral administration of the freely water-soluble drug--CedH.