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Sample records for circulating erythrocyte-derived microparticles

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

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    Ruzica Livaja Koshiar

    Full Text Available 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isolated using ultracentrifugation after incubation of freshly prepared erythrocytes with the ionophore A23187 or from outdated erythrocyte concentrates, the different microparticles preparations yielding similar results.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

  2. Circulating Endothelial Microparticles in Diabetes Mellitus

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    A. F. Tramontano

    2010-01-01

    Full Text Available Background. Endothelial Microparticles (EMPs are small vesicles shed from activated or apoptotic endothelial cells and involved in cellular cross-talk. Whether EMP immunophenotypes vary according to stimulus in Diabetes Mellitus (DM is not known. We studied the cellular adhesion molecule (CAM profile of circulating EMPs in patients with and without Diabetes Mellitus type 2, who were undergoing elective cardiac catheterization. Methods and Results. EMPs were analyzed by flow cytometry. The absolute median number of EMPs (EMPs/L specific for CD31, CD105, and CD106 was significantly increased in the DM population. The ratio of CD62E/CD31 EMP populations reflected an apoptotic process. Conclusion. Circulating CD31+, CD105+, and CD106+ EMPs were significantly elevated in patients with DM. EMPs were the only independent predictors of DM in our study cohort. In addition, the EMP immunophenotype reflected an apoptotic process. Circulating EMPs may provide new options for risk assessment.

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

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    Keshav Raj Paudel

    2016-01-01

    Full Text Available 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.

  4. Quantitative proteome profiling of normal human circulating microparticles

    DEFF Research Database (Denmark)

    Østergaard, Ole; Nielsen, Christoffer T; Iversen, Line V;

    2012-01-01

    Circulating microparticles (MPs) are produced as part of normal physiology. Their numbers, origin, and composition change in pathology. Despite this, the normal MP proteome has not yet been characterized with standardized high-resolution methods. We here quantitatively profile the normal MP...... proteome using nano-LC-MS/MS on an LTQ-Orbitrap with optimized sample collection, preparation, and analysis of 12 different normal samples. Analytical and procedural variation were estimated in triply processed samples analyzed in triplicate from two different donors. Label-free quantitation was validated...... by the correlation of cytoskeletal protein intensities with MP numbers obtained by flow cytometry. Finally, the validity of using pooled samples was evaluated using overlap protein identification numbers and multivariate data analysis. Using conservative parameters, 536 different unique proteins were quantitated...

  5. Clinical CVVH model removes endothelium-derived microparticles from circulation

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    Abdelhafeez H. Abdelhafeez

    2014-02-01

    Full Text Available Background: Endothelium-derived microparticles (EMPs are submicron vesicles released from the plasma membrane of endothelial cells in response to injury, apoptosis or activation. We have previously demonstrated EMP-induced acute lung injury (ALI in animal models and endothelial barrier dysfunction in vitro. Current treatment options for ALI are limited and consist of supportive therapies. We hypothesize that standard clinical continuous venovenous hemofiltration (CVVH reduces serum EMP levels and may be adapted as a potential therapeutic intervention. Materials and methods: EMPs were generated from plasminogen activation inhibitor-1 (PAI-1-stimulated human umbilical vein endothelial cells (HUVECs. Flow cytometric analysis was used to characterize EMPs as CD31- and annexin V-positive events in a submicron size gate. Enumeration was completed against a known concentration of latex beads. Ultimately, a concentration of ~650,000 EMP/mL perfusate fluid (total 470 mL was circulated through a standard CVVH filter (pore size 200 μm, flow rate 250 mL/hr for a period of 70 minutes. 0.5 mL aliquots were removed at 5- to 10-minute intervals for flow cytometric analysis. EMP concentration in the dialysate was measured at the end of 4 hours to better understand the fate of EMPs. Results: A progressive decrease in circulating EMP concentration was noted using standard CVVH at 250 mL/hr (a clinical standard rate from a 470 mL volume modelling a patient's circulation. A 50% reduction was noted within the first 30 minutes. EMPs entering the dialysate after 4 hours were 5.7% of the EMP original concentration. Conclusion: These data demonstrate that standard CVVH can remove EMPs from circulation in a circuit modelling a patient. An animal model of hemofiltration with induction of EMP release is required to test the therapeutic potential of this finding and potential of application in early treatment of ALI.

  6. Galectin-3 binding protein links circulating microparticles with electron dense glomerular deposits in lupus nephritis

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    Nielsen, C T; Østergaard, O; Rekvig, O P;

    2015-01-01

    OBJECTIVE: A high level of galectin-3-binding protein (G3BP) appears to distinguish circulating cell-derived microparticles in systemic lupus erythematosus (SLE). The aim of this study is to characterize the population of G3BP-positive microparticles from SLE patients compared to healthy controls......, explore putative clinical correlates, and examine if G3BP is present in immune complex deposits in kidney biopsies from patients with lupus nephritis. METHODS: Numbers of annexin V-binding and G3BP-exposing plasma microparticles from 56 SLE patients and 36 healthy controls were determined by flow...... in kidney biopsies from one non-SLE control and from patients with class IV (n = 2) and class V (n = 1) lupus nephritis using co-localization immune electron microscopy. RESULTS: Microparticle-G3BP, microparticle-C1q and microparticle-immunoglobulins were significantly (P 

  7. Distinct features of circulating microparticles and their relationship to clinical manifestations in systemic lupus erythematosus

    DEFF Research Database (Denmark)

    Nielsen, Christoffer T; Østergaard, Ole; Johnsen, Christina;

    2011-01-01

    Characterization of the abundance, origin, and annexin V (AnxV)-binding capabilities of circulating microparticles (MPs) in SLE patients and healthy controls and to determine any associations with clinical parameters....

  8. Circulating endothelial cells and microparticles as prognostic markers in advanced non-small cell lung cancer.

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    Tania Fleitas

    Full Text Available BACKGROUND: Circulating endothelial cells and microparticles have prognostic value in cancer, and might be predictors of response to chemotherapy and antiangiogenic treatments. We have investigated the prognostic value of circulating endothelial cells and microparticles in patients treated for advanced non-small cell lung cancer. METHODOLOGY/PRINCIPAL FINDINGS: Peripheral blood samples were obtained from 60 patients before first line, platinum-based chemotherapy +/- bevacizumab, and after the third cycle of treatment. Blood samples from 60 healthy volunteers were also obtained as controls. Circulating endothelial cells were measured by an immunomagnetic technique and immunofluorescence microscopy. Phosphatidylserine-positive microparticles were evaluated by flow cytometry. Microparticle-mediated procoagulant activity was measured by the endogen thrombin generation assay. RESULTS: pre- and posttreatment levels of markers were higher in patients than in controls (p<0.0001. Elevated levels of microparticles were associated with longer survival. Elevated pretreatment levels of circulating endothelial cells were associated with shorter survival. CONCLUSIONS/SIGNIFICANCE: Circulating levels of microparticles and circulating endothelial cells correlate with prognosis, and could be useful as prognostic markers in patients with advanced non-small cell lung cancer.

  9. Circulating endothelial cells and procoagulant microparticles in patients with glioblastoma: prognostic value.

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    Gaspar Reynés

    Full Text Available AIM: Circulating endothelial cells and microparticles are prognostic factors in cancer. However, their prognostic and predictive value in patients with glioblastoma is unclear. The objective of this study was to investigate the potential prognostic value of circulating endothelial cells and microparticles in patients with newly diagnosed glioblastoma treated with standard radiotherapy and concomitant temozolomide. In addition, we have analyzed the methylation status of the MGMT promoter. METHODS: Peripheral blood samples were obtained before and at the end of the concomitant treatment. Blood samples from healthy volunteers were also obtained as controls. Endothelial cells were measured by an immunomagnetic technique and immunofluorescence microscopy. Microparticles were quantified by flow cytometry. Microparticle-mediated procoagulant activity was measured by endogen thrombin generation and by phospholipid-dependent clotting time. Methylation status of MGMT promoter was determined by multiplex ligation-dependent probe amplification. RESULTS: Pretreatment levels of circulating endothelial cells and microparticles were higher in patients than in controls (p<0.001. After treatment, levels of microparticles and thrombin generation decreased, and phospholipid-dependent clotting time increased significantly. A high pretreatment endothelial cell count, corresponding to the 99(th percentile in controls, was associated with poor overall survival. MGMT promoter methylation was present in 27% of tumor samples and was associated to a higher overall survival (66 weeks vs 30 weeks, p<0.004. CONCLUSION: Levels of circulating endothelial cells may have prognostic value in patients with glioblastoma.

  10. Circulating CD62E+ microparticles and cardiovascular outcomes.

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    Soon-Tae Lee

    Full Text Available BACKGROUND: Activated endothelial cells release plasma membrane submicron vesicles expressing CD62E (E-selectin into blood, known as endothelial microparticles (EMPs. We studied whether the levels of endothelial microparticles expressing CD62E(+, CD31(+/Annexin-V(+, or CD31(+/CD42(- predict cardiovascular outcomes in patients with stroke history. METHODS/PRINCIPAL FINDINGS: Patients with stroke history at least 3 months prior to enrolment were recruited. Peripheral blood EMP levels were measured by flow cytometry. Major cardiovascular events and death were monitored for 36 months. Three hundred patients were enrolled, of which 298 completed the study according to protocol. Major cardiovascular events occurred in 29 patients (9.7%. Nine patients died, five from cardiovascular causes. Cumulative event-free survival rates were lower in patients with high levels of CD62E(+ microparticles. Multivariate Cox regression analysis adjusted for cardiovascular risk factors, medications and stroke etiologic groups showed an association between a high CD62E(+ microparticle level and a risk of major cardiovascular events and hospitalization. Levels of other kinds of EMPs expressing CD31(+/Annexin-V(+ or CD31(+/CD42(- markers were not predictive of cardiovascular outcomes. CONCLUSION: A high level of CD62E(+ microparticles is associated with cardiovascular events in patients with stroke history, suggesting that the systemic endothelial activation increases the risk for cardiovascular morbidities.

  11. Leukocyte Activation and Circulating Leukocyte-Derived Microparticles in Preeclampsia

    NARCIS (Netherlands)

    Lok, Christianne A. R.; Jebbink, Jiska; Nieuwland, Rienk; Faas, Marijke M.; Boer, Kees; Sturk, Augueste; Van Der Post, Joris A. M.

    2009-01-01

    Preeclampsia shows characteristics of an inflammatory disease including leukocyte activation. Analyses of leukocyte-derived microparticles (MP) and mRNA expression of inflammation-related genes in leukocytes may establish which subgroups of leukocytes contribute to the development of preeclampsia. B

  12. Unique Protein Signature of Circulating Microparticles in Systemic Lupus Erythematosus

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    Østergaard, Ole; Nielsen, Christoffer; Iversen, Line V;

    2013-01-01

    To characterize the unique qualities of proteins associated with circulating subcellular material in systemic lupus erythematosus (SLE) patients compared with healthy controls and patients with other chronic autoimmune diseases.......To characterize the unique qualities of proteins associated with circulating subcellular material in systemic lupus erythematosus (SLE) patients compared with healthy controls and patients with other chronic autoimmune diseases....

  13. Circulating microparticles and plasma levels of soluble E- and P-selectins in patients with systemic sclerosis

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    Iversen, Lars; Østergaard, O; Ullman, S;

    2013-01-01

    Microparticles (MPs) may be involved in the pathogenesis of systemic sclerosis (SSc), which includes vasculopathy, endothelial cell activation, and coagulation activation. Circulating MPs from SSc patients were characterized and their relationship with soluble markers of vascular activation inves...

  14. Circulating Endothelial Progenitor Cell and Platelet Microparticle Impact on Platelet Activation in Hypertension Associated with Hypercholesterolemia

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    Nicoleta Alexandru; Doina Popov; Emanuel Dragan; Eugen Andrei; Adriana Georgescu

    2013-01-01

    AIM: The purpose of this project was to evaluate the influence of circulating endothelial progenitor cells (EPCs) and platelet microparticles (PMPs) on blood platelet function in experimental hypertension associated with hypercholesterolemia. METHODS: Golden Syrian hamsters were divided in six groups: (i) control, C; (ii) hypertensive-hypercholesterolemic, HH; (iii) 'prevention', HHin-EPCs, HH animals fed a HH diet and treated with EPCs; (iv) 'regression', HHfin-EPCs, HH treated with EPCs aft...

  15. Circulating platelet and erythrocyte microparticles in young children and adolescents with sickle cell disease: Relation to cardiovascular complications.

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    Tantawy, Azza Abdel Gawad; Adly, Amira Abdel Moneam; Ismail, Eman Abdel Rahman; Habeeb, Nevin Mamdouh; Farouk, Amal

    2013-01-01

    Sickle cell disease (SCD) is characterized by a complex vasculopathy, consisting of endothelial dysfunction and increased arterial stiffness, with a global effect on cardiovascular function. The hypercoagulable state may result from chronic hemolysis and circulating cell-derived microparticles (MPs) originating mainly from activated platelets and erythrocytes. We measured the levels of platelet and erythrocyte-derived MPs (PMPs and ErMPs) in 50 young SCD patients compared with 40 age- and sex-matched healthy controls and assessed their relation to clinicopathological characteristics and aortic elastic properties. Patients were studied stressing on the occurrence of sickling crisis, transfusion history, hydroxyurea therapy, hematological, and coagulation profile as well as flow cytometric expression of PMPs (CD41b(+)) and ErMPs (glycophorin A(+)). Echocardiography was performed to assess aortic stiffness and distensibility, left ventricular function and pulmonary artery pressure. Both PMPs and ErMPs were significantly elevated in SCD patients compared with control group (p < 0.001). SCD patients had significantly elevated d-dimer and von Willebrand factor antigen (vWF Ag) levels with lower antithrombin III compared with controls (p < 0.001). Aortic stiffness index and pulmonary artery pressure were significantly higher in SCD (p < 0.001), whereas aortic strain and aortic distensibility were significantly lower (p < 0.001) compared with controls. MPs levels were significantly increased in SCD patients with pulmonary hypertension, acute chest syndrome, and stroke as well as those who had history of thrombosis or splenectomy (p < 0.001). Also, patients in sickling crisis during the study had higher PMPs and ErMPs levels than those in steady state (p < 0.001). Patients on hydroxyurea therapy had lower MPs levels than untreated patients (p < 0.001). PMPs and ErMPs were positively correlated with disease duration, transfusion index, white blood

  16. Circulating microparticles carry oxidation-specific epitopes and are recognized by natural IgM antibodies.

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    Tsiantoulas, Dimitrios; Perkmann, Thomas; Afonyushkin, Taras; Mangold, Andreas; Prohaska, Thomas A; Papac-Milicevic, Nikolina; Millischer, Vincent; Bartel, Caroline; Hörkkö, Sohvi; Boulanger, Chantal M; Tsimikas, Sotirios; Fischer, Michael B; Witztum, Joseph L; Lang, Irene M; Binder, Christoph J

    2015-02-01

    Oxidation-specific epitopes (OSEs) present on apoptotic cells and oxidized low density lipoprotein (OxLDL) represent danger-associated molecular patterns that are recognized by different arcs of innate immunity, including natural IgM antibodies. Here, we investigated whether circulating microparticles (MPs), which are small membrane vesicles released by apoptotic or activated cells, are physiological carriers of OSEs. OSEs on circulating MPs isolated from healthy donors and patients with ST-segment elevation myocardial infarction (STE-MI) were characterized by flow cytometry using a panel of OSE-specific monoclonal antibodies. We found that a subset of MPs carry OSEs on their surface, predominantly malondialdehyde (MDA) epitopes. Consistent with this, a majority of IgM antibodies bound on the surface of circulating MPs were found to have specificity for MDA-modified LDL. Moreover, we show that MPs can stimulate THP-1 (human acute monocytic leukemia cell line) and human primary monocytes to produce interleukin 8, which can be inhibited by a monoclonal IgM with specificity for MDA epitopes. Finally, we show that MDA(+) MPs are elevated at the culprit lesion site of patients with STE-MI. Our results identify a subset of OSE(+) MPs that are bound by OxLDL-specific IgM. These findings demonstrate a novel mechanism by which anti-OxLDL IgM antibodies could mediate protective functions in CVD.

  17. Annual FEV1 changes and numbers of circulating endothelial microparticles in patients with COPD: a prospective study

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    Takahashi, Toru; Kobayashi, Seiichi; Fujino, Naoya; Suzuki, Takaya; Ota, Chiharu; Tando, Yukiko; Yamada, Mitsuhiro; Yanai, Masaru; Yamaya, Mutsuo; Kurosawa, Shin; Yamauchi, Masanori; Kubo, Hiroshi

    2014-01-01

    Objective Growing evidence suggests that endothelial injury is involved in the pathophysiology of chronic obstructive pulmonary disease (COPD). Circulating endothelial microparticles (EMPs) increase in patients with COPD because of the presence of endothelial injury. We examined the relationship between EMP number and changes in forced expiratory volume in 1 s (FEV1) in patients with COPD. Design Prospective study. Setting One hospital in Japan. Participants A total 48 outpatients with stable...

  18. Circulating endothelial progenitor cell and platelet microparticle impact on platelet activation in hypertension associated with hypercholesterolemia.

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    Nicoleta Alexandru

    Full Text Available AIM: The purpose of this project was to evaluate the influence of circulating endothelial progenitor cells (EPCs and platelet microparticles (PMPs on blood platelet function in experimental hypertension associated with hypercholesterolemia. METHODS: Golden Syrian hamsters were divided in six groups: (i control, C; (ii hypertensive-hypercholesterolemic, HH; (iii 'prevention', HHin-EPCs, HH animals fed a HH diet and treated with EPCs; (iv 'regression', HHfin-EPCs, HH treated with EPCs after HH feeding; (v HH treated with PMPs, HH-PMPs, and (vi HH treated with EPCs and PMPs, HH-EPCs-PMPs. RESULTS: Compared to HH group, the platelets from HHin-EPCs and HHfin-EPCs groups showed a reduction of: (i activation, reflected by decreased integrin 3β, FAK, PI3K, src protein expression; (ii secreted molecules as: SDF-1, MCP-1, RANTES, VEGF, PF4, PDGF and (iii expression of pro-inflammatory molecules as: SDF-1, MCP-1, RANTES, IL-6, IL-1β; TFPI secretion was increased. Compared to HH group, platelets of HH-PMPs group showed increased activation, molecules release and proteins expression. Compared to HH-PMPs group the combination EPCs with PMPs treatment induced a decrease of all investigated platelet molecules, however not comparable with that recorded when EPC individual treatment was applied. CONCLUSION: EPCs have the ability to reduce platelet activation and to modulate their pro-inflammatory and anti-thrombogenic properties in hypertension associated with hypercholesterolemia. Although, PMPs have several beneficial effects in combination with EPCs, these did not improve the EPC effects. These findings reveal a new biological role of circulating EPCs in platelet function regulation, and may contribute to understand their cross talk, and the mechanisms of atherosclerosis.

  19. Hypoxia Mediated Release of Endothelial Microparticles and Increased Association of S100A12 with Circulating Neutrophils

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    Rebecca V. Vince

    2009-01-01

    Full Text Available Microparticles are released from the endothelium under normal homeostatic conditions and have been shown elevated in disease states, most notably those characterised by endothelial dysfunction. The endothelium is sensitive to oxidative stress/status and vascular cell adhesion molecule-1 (VCAM-1 expression is upregulated upon activated endothelium, furthermore the presence of VCAM-1 on microparticles is known. S100A12, a calcium binding protein part of the S100 family, is shown to be present on circulating leukocytes and is thought a sensitive marker to local inflammatory process, which may be driven by oxidative stress. Eight healthy males were subjected to breathing hypoxic air (15% O2, approximately equivalent to 3000 metres altitude for 80 minutes in a temperature controlled laboratory and venous blood samples were processed immediately for VCAM-1 microparticles (VCAM-1 MP and S100A12 association with leukocytes by flow cytometry. A pre-hypoxic blood sample was used for comparison. Both VCAM-1 MP and S100A12 association with neutrophils were significantly elevated post hypoxic breathing later declining to levels observed in the pre-test samples. A similar trend was observed in both cases and a correlation may exist between these two markers in response to hypoxia. These data offer evidence using novel markers of endothelial and circulating blood responses to hypoxia.

  20. Circulating microparticles carry oxidation-specific epitopes and are recognized by natural IgM antibodies1[S

    Science.gov (United States)

    Tsiantoulas, Dimitrios; Perkmann, Thomas; Afonyushkin, Taras; Mangold, Andreas; Prohaska, Thomas A.; Papac-Milicevic, Nikolina; Millischer, Vincent; Bartel, Caroline; Hörkkö, Sohvi; Boulanger, Chantal M.; Tsimikas, Sotirios; Fischer, Michael B.; Witztum, Joseph L.; Lang, Irene M.; Binder, Christoph J.

    2015-01-01

    Oxidation-specific epitopes (OSEs) present on apoptotic cells and oxidized low density lipoprotein (OxLDL) represent danger-associated molecular patterns that are recognized by different arcs of innate immunity, including natural IgM antibodies. Here, we investigated whether circulating microparticles (MPs), which are small membrane vesicles released by apoptotic or activated cells, are physiological carriers of OSEs. OSEs on circulating MPs isolated from healthy donors and patients with ST-segment elevation myocardial infarction (STE-MI) were characterized by flow cytometry using a panel of OSE-specific monoclonal antibodies. We found that a subset of MPs carry OSEs on their surface, predominantly malondialdehyde (MDA) epitopes. Consistent with this, a majority of IgM antibodies bound on the surface of circulating MPs were found to have specificity for MDA-modified LDL. Moreover, we show that MPs can stimulate THP-1 (human acute monocytic leukemia cell line) and human primary monocytes to produce interleukin 8, which can be inhibited by a monoclonal IgM with specificity for MDA epitopes. Finally, we show that MDA+ MPs are elevated at the culprit lesion site of patients with STE-MI. Our results identify a subset of OSE+ MPs that are bound by OxLDL-specific IgM. These findings demonstrate a novel mechanism by which anti-OxLDL IgM antibodies could mediate protective functions in CVD. PMID:25525116

  1. Action mechanisms of a new erythrocyte-derived depressing factor

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    To investigate the action mechanisms of a new erythrocyte-derived depressing factor (EDDF), the focus is placed on the effect of EDDF on both cytosolic and nuclear free calcium (Ca2+) transportation in vascular smooth muscle cell (VSMC), as well as the apoptosis and cell cycle of VSMC of rats. EDDF has been extracted from human erythrocytes. The changes of Ca2+ levels in cytoplasm ([Ca2+]i) and nucleus ([Ca2+]n) have been observed using a laser scanning confocal microscope together with fluo-3/AM as a calcium indicator. Flow cytometric technique was used to study the effect of EDDF on cell cycle and apoptosis of VSMC. [Ca2+]i and [Ca2+]n were significantly decreased through several different pathways: (ⅰ) it reduced the Ca2+ influx by blocking L-type voltage-dependent calcium channel (L-VDC) and R-type voltage-dependent calcium channel (R-VDC); (ⅱ) it inhibited the Ca2+ release from inositol 1, 4, 5-trisphosphate (IP3) sensitive calcium store; and (ⅲ) activated Ca2+-ATPase of sarcoplasmic reticulum (SR) and promoted the transportation of Ca2+ from cytoplasm to SR. However, EDDF seemed to have little inhibitory effect on the Ca2+ release from ryonodine sensitive calcium pool. It was also found that EDDF (104 g/mL) significantly decreased the proportion of S phase of human umbilical vein (HUV) and inhibited the proliferation of VSMC induced by angiotensin Ⅱ (AngⅡ, 105 mol/L). The apopotosis did not occur when VSMC was cultured under normal condition. While VSMC apoptosis was induced by AngII (10-5 mol/L) and EDDF (104 g/mL) seemed to have little effect on it. The inhibitory effect of EDDF on the elevation of [Ca2+]i and [Ca2+]n of VSMC might play an essential role in its action mechanisms and the ways it affects the Ca2+ handling of VSMC demonstrate that EDDF was different from other endogenous blood pressure regulators and some known antihypertensive drugs. EDDF could inhibit the proliferation of VSMC, which indicated that it might be beneficial to the

  2. Circulating microparticles and the risk of thrombosis in inherited deficiencies of antithrombin, protein C and protein S.

    Science.gov (United States)

    Campello, Elena; Spiezia, Luca; Radu, Claudia M; Bulato, Cristiana; Gavasso, Sabrina; Tormene, Daniela; Woodhams, Barry; Dalla Valle, Fabio; Simioni, Paolo

    2016-01-01

    Many subjects carrying inherited thrombophilic defects will never experience venous thromboembolism (VTE) while other individuals developed recurrent VTE with no known additional risk factors. High levels of circulating microparticles (MP) have been associated with increased risk of VTE in patients with factor V Leiden and prothrombin G20210A mutation, suggesting a possible contribution of MP in the hypercoagulability of mild genetic thrombophilia. The role of MP as additional risk factor of VTE in carriers of natural clotting inhibitors defects (severe thrombophilia) has never been assessed. Plasma levels of annexin V-MP, endothelial-derived MP (EMP), platelet-derived MP (PMP), tissue factor-bearing MP (TF+) and the MP procoagulant activity (PPL) were measured in 132 carriers of natural anticoagulant deficiencies (25 antithrombin, 63 protein C and 64 protein S defect) and in 132 age and gender-matched healthy controls. Carriers of natural anticoagulant deficiencies, overall and separately considered, presented with higher median levels of annexin V-MP, EMP, PMP, TF+MP and PPL activity than healthy controls (pEMP and PMP had an adjusted OR for VTE of 3.36 (95% CI, 1.59 to 7.11), 9.26 (95% CI, 3.55 to 24.1) and 2.72 (95%CI, 1.16 to 6.38), respectively. Elevated levels of circulating MP can play a role in carriers of mild and severe inherited thrombophilia. The clinical implications of this association remain to be defined. PMID:26354831

  3. Data on the circulating levels of endothelial microparticles are elevated in patients with bicuspid aortic valve and are related to aortic dilation

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    Josep M. Alegret

    2016-09-01

    Full Text Available The data included here support the research article “Circulating endothelial microparticles are elevated in bicuspid aortic valve (BAV disease and related to aortic dilation” (Alegret et al., 2016 [1] where circulating levels of platelet endothelial cell adhesion molecule (PECAM+ endothelial microparticles (EMPs were identified as a biological variable related to aortic dilation in patients with BAV disease. The data presented in this article are composed by four tables and one figure containing the clinical and echocardiographic characteristics of the patients (Alegret et al., 2016 [1] included in this study, and summarize the results of multivariate linear analyses. Furthermore, is also included a figure showing a representative flow cytometry dot plots and histograms used in PECAM+ EMPs quantification is also included.

  4. Circulating Endothelial Microparticles and Correlation of Serum 1,25-Dihydroxyvitamin D with Adiponectin, Nonesterified Fatty Acids, and Glycerol from Middle-Aged Men in China

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    Zhongxiao Wan

    2016-01-01

    Full Text Available The aim of the present study is (1 to determine the correlation between circulating 1,25-dihydroxyvitamin D [25(OHD] and adiponectin, nonesterified fatty acids (NEFAs, and glycerol and (2 to determine the alterations in circulating endothelial microparticles (EMPs in Chinese male subjects with increased body mass index (BMI. A total of 45 male adults were enrolled with varied BMI [i.e., lean, overweight (OW, and obese (OB, N=15 per group]. Blood samples were collected under overnight fasting condition, and plasma was isolated for the measurement of endothelial microparticles (EMPs, total and high-molecular weight (HMW adiponectin, 25(OHD, nonesterified fatty acids (NEFAs, and glycerol. Circulating 25(OHD levels were inversely associated with total adiponectin, NEFA, and glycerol levels. There is no difference for CD62E+ or CD31+/CD42b− EMPs among 3 groups. In Chinese male adults with varied BMI, an inverse correlation existed between 25(OHD levels and total adiponectin, NEFA, and glycerol levels; and there is no significant difference for CD62E+ or CD31+/CD42b− EMPs among lean, overweight, and obese subjects.

  5. Effect of Abciximab on the Levels of Circulating Microparticles in Patients with Acute Myocardial Infarction Treated by Primary Angioplasty

    OpenAIRE

    Cha, Jung-Joon; Kim, Jong-Youn; Choi, Eui-Young; Min, Pil-Ki; Cho, Minhee; Lee, Da-Lyung; Hong, Sung-Yu; Yoon, Young-Won; Lee, Byoung Kwon; Hong, Bum-Kee; Rim, Se-Joong; Kwon, Hyuck Moon

    2013-01-01

    Background and Objectives We investigated the effect of the additional use of abciximab during percutaneous coronary intervention (PCI) on the level of procoagulant microparticles (MPs) in patients with ST-segment elevation myocardial infarction (STEMI) who had undergone primary PCI. Subjects and Methods In this study, we studied 86 patients with STEMI (72 men, age 58±13) who had undergone primary PCI. The decision to administer abciximab immediately prior to PCI was left to the discretion of...

  6. Circulating Endothelial-Derived Activated Microparticle: A Useful Biomarker for Predicting One-Year Mortality in Patients with Advanced Non-Small Cell Lung Cancer

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    Chin-Chou Wang

    2014-01-01

    Full Text Available Background. This study tested the hypothesis that circulating microparticles (MPs are useful biomarkers for predicting one-year mortality in patients with end-stage non-small cell lung cancer (ES-NSCLC. Methods and Results. One hundred seven patients were prospectively enrolled into the study between April 2011 and February 2012, and each patient received regular follow-up after enrollment. Levels of four MPs in circulation, (1 platelet-derived activated MPs (PDAc-MPs, (2 platelet-derived apoptotic MPs (PDAp-MPs, (3 endothelial-derived activated MPs (EDAc-MPs, and (4 endothelial-derived apoptotic MPs (EDAp-MPs, were measured just after the patient was enrolled into the study using flow cytometry. Patients who survived for more than one year were categorized into group 1 (n=56 (one-year survivors and patients who survived less than one year were categorized into group 2 (n=51 (one-year nonsurvivors. Male gender, incidence of liver metastasis, progression of disease after first-line treatment, poor performance status, and the Charlson comorbidity index were significantly higher in group 2 than in group 1 (all P<0.05. Additionally, as measured by flow cytometry, only the circulating level of EDAc-MPs was found to be significantly higher in group 2 than in group 1 (P=0.006. Multivariate analysis demonstrated that circulating level of EDAc-MPs along with brain metastasis and male gender significantly and independently predictive of one-year mortality (all P<0.035. Conclusion. Circulating EDAc-MPs may be a useful biomarker predictive of one-year morality in ES-NSCLC patients.

  7. Circulating microparticles, protein C, free protein S and endothelial vascular markers in children with sickle cell anaemia

    Directory of Open Access Journals (Sweden)

    Andrea Piccin

    2015-11-01

    Full Text Available Introduction: Circulating microparticles (MP have been described in sickle cell anaemia (SCA; however, their interaction with endothelial markers remains unclear. We investigated the relationship between MP, protein C (PC, free protein S (PS, nitric oxide (NO, endothelin-1 (ET-1 and adrenomedullin (ADM in a large cohort of paediatric patients. Method: A total of 111 children of African ethnicity with SCA: 51 in steady state; 15 in crises; 30 on hydroxyurea (HU therapy; 15 on transfusion; 17 controls (HbAA of similar age/ethnicity. MP were analysed by flow cytometry using: Annexin V (AV, CD61, CD42a, CD62P, CD235a, CD14, CD142 (tissue factor, CD201 (endothelial PC receptor, CD62E, CD36 (TSP-1, CD47 (TSP-1 receptor, CD31 (PECAM, CD144 (VE-cadherin. Protein C, free PS, NO, pro-ADM and C-terminal ET-1 were also measured. Results: Total MP AV was lower in crisis (1.26×106 ml−1; 0.56–2.44×106 and steady state (1.35×106 ml−1; 0.71–3.0×106 compared to transfusion (4.33×106 ml−1; 1.6–9.2×106, p0.9, p<0.05 between total numbers of AV-positive MP (MP AV and platelet MP expressing non-activation platelet markers. There was a lower correlation between MP AV and MP CD62P (R=0.73, p<0.05 (platelet activation marker, and also a lower correlation between percentage of MP expressing CD201 (%MP CD201 and %MP CD14 (R=0.627, p<0.001. %MP CD201 was higher in crisis (11.6% compared with HbAA (3.2%, p<0.05; %MP CD144 was higher in crisis (7.6% compared with transfusion (2.1%, p<0.05; %CD14 (0.77% was higher in crisis compared with transfusion (0.0%, p<0.05 and steady state (0.0%, p<0.01; MP CD14 was detectable in a higher number of samples (92% in crisis compared with the rest (40%; %MP CD235a was higher in crisis (17.9% compared with transfusion (8.9%, HU (8.7% and steady state (9.9%, p<0.05; %CD62E did not differ significantly across the groups and CD142 was undetectable. Pro-ADM levels were raised in chest crisis: 0.38 nmol L−1 (0.31–0

  8. Circulating Endothelial-Derived Apoptotic Microparticles in the Patients with Ischemic Symptomatic Chronic Heart Failure: Relevance of Pro-Inflammatory Activation and Outcomes

    Directory of Open Access Journals (Sweden)

    Alexander E. Berezin

    2014-09-01

    Full Text Available Background: Endothelial-derived apoptotic microparticles (EMPs play a pivotal role in endothelial dysfunction in hronic Heart Failure (CHF. Objectives: The present study aimed to evaluate the association between EMPs and pro-inflammatory biomarkers, clinical status, and outcomes in the patients with ischemic CHF. Patients and Methods: This study was conducted on 154 patients with ischemic symptomatic moderate-to-severe CHF on discharge from hospital. The observation period was up to 3 years. Circulating NT-pro-BNP, TNF-alpha, sFas, and sFas ligand were determined at baseline. Flow cytometry analysis was used for quantifying the number of EMPs. All-cause mortality, CHF-related death, and CHD-re-hospitalization rate were examined. The data were analyzed using descriptive statistics, Receive Operation Characteristic Curve (ROC, and logistic regression analysis. Besides, P 0.514 n/mL and those with a low level of the biomarker (< 0.514 n/mL regarding their survival. The number of circulating EPMs independently predicted all-cause mortality (OR = 1.58; 95% CI = 1.20 – 1.88; P = 0.001, CHF-related death (OR = 1.22; 95% CI: 1.12 – 1.36; P < 0.001, and CHF-related re-hospitalization (OR = 1.20; 95% CI: 1.11 – 1.32; P < 0.001. Conclusions: Among the patients with symptoms of CHF, increased number of circulating EMPs was associated with increased 3-year CHF-related death, all-cause mortality, and risk of recurrent hospitalization due to CHF.

  9. Increased circulating cell-derived microparticle count is associated with recurrent implantation failure after IVF and embryo transfer.

    Science.gov (United States)

    Martínez-Zamora, M Angeles; Tàssies, Dolors; Reverter, Juan Carlos; Creus, Montserrat; Casals, Gemma; Cívico, Salvadora; Carmona, Francisco; Balasch, Juan

    2016-08-01

    Cell-derived microparticles (cMPs) are small membrane vesicles that are released from many different cell types in response to cellular activation or apoptosis. Elevated cMP counts have been found in almost all thrombotic diseases and pregnancy wastage, such as recurrent spontaneous abortion and in a number of conditions associated with inflammation, cellular activation and angiogenesis. cMP count was investigated in patients experiencing unexplained recurrent implantation failure (RIF). The study group was composed of 30 women diagnosed with RIF (RIF group). The first control group (IVF group) (n = 30) comprised patients undergoing a first successful IVF cycle. The second control group (FER group) included 30 healthy women who had at least one child born at term and no history of infertility or obstetric complications. cMP count was significantly higher in the RIF group compared with the IVF and FER groups (P < 0.05 and P < 0.01, respectively) (RIF group: 15.8 ± 6.2 nM phosphatidylserine equivalent [PS eq]; IVF group: 10.9 ± 5.3 nM PS eq; FER group: 9.6 ± 4.0 nM PS eq). No statistical difference was found in cMP count between the IVF and FER groups. Increased cMP count is, therefore, associated with RIF after IVF and embryo transfer.

  10. Protective role of a novel human erythrocyte-derived depressing factor on blood vessels in rats

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The protective role of a human erythrocyte-derived depressing factor (EDDF) on blood vessels was evaluated. The experiments were carried out on 25male Wistar rats aged 6-8 weeks, which were divided into control (n = 8), calcium overload (n = 8) and NG-L-nitro-arginine hypertensive model groups (L-NNA,n = 9), respectively. The isolated vascular ring perfusion assay, two-photon laser scanning fluorescence microscopy (TPM) and transmitted electron microscope were used to examine the effect of EDDF on vascular function and ultrastructure. Results showed that the contractile response of calcium overload rats and L-NNA rats to phenylephrine (PE) was significantly enhanced compared with that of the control (P < 0.05), and EDDF (10-3 g @mL-1) remarkably decreased the vascular contractile response of control's and calcium overload rats (P < 0.05),while EDDF had no effect on that of L-NNA rats. EDDF also alleviated the ultrastructural lesion of aorta VSMC in calcium overload rats by easing the abnormal in the nucleus, mitochondrion and other organell. It is concluded that EDDF could efficiently protect blood vessels against injury by influencing Ca2+ transport and ameliorating the lesion of VSMC, and further supported the hypothesis that the NO-cGMP pathway might contribute to the vasodilation and partially antihypertensive mechanism of EDDF.``

  11. Differential impact of acute high-intensity exercise on circulating endothelial microparticles and insulin resistance between overweight/obese males and females.

    Directory of Open Access Journals (Sweden)

    Cody Durrer

    Full Text Available An acute bout of exercise can improve endothelial function and insulin sensitivity when measured on the day following exercise. Our aim was to compare acute high-intensity continuous exercise (HICE to high-intensity interval exercise (HIIE on circulating endothelial microparticles (EMPs and insulin sensitivity in overweight/obese men and women.Inactive males (BMI = 30 ± 3, 25 ± 6 yr, n = 6 and females (BMI = 28 ± 2, 21 ± 3 yr, n = 7 participated in three experimental trials in a randomized counterbalanced crossover design: 1 No exercise control (Control; 2 HICE (20 min cycling @ just above ventilatory threshold; 3 HIIE (10 X 1-min @ ∼ 90% peak aerobic power. Exercise conditions were matched for external work and diet was controlled post-exercise. Fasting blood samples were obtained ∼ 18 hr after each condition. CD62E(+ and CD31(+/CD42b- EMPs were assessed by flow cytometry and insulin resistance (IR was estimated by homeostasis model assessment (HOMA-IR.There was a significant sex X exercise interaction for CD62E(+ EMPs, CD31(+/CD42b- EMPs, and HOMA-IR (all P < 0.05. In males, both HICE and HIIE reduced EMPs compared to Control (P ≤ 0.05. In females, HICE increased CD62E(+ EMPs (P < 0.05 vs. Control whereas CD31(+/CD42b- EMPs were unaltered by either exercise type. There was a significant increase in HOMA-IR in males but a decrease in females following HIIE compared to Control (P<0.05.Overweight/obese males and females appear to respond differently to acute bouts of high-intensity exercise. A single session of HICE and HIIE reduced circulating EMPs measured on the morning following exercise in males but in females CD62E(+ EMPs were increased following HICE. Next day HOMA-IR paradoxically increased in males but was reduced in females following HIIE. Future research is needed to investigate mechanisms responsible for potential differential responses between males and females.

  12. Role of microparticles in endothelial dysfunction and arterial hypertension

    Institute of Scientific and Technical Information of China (English)

    Thomas; Helbing; Christoph; Olivier; Christoph; Bode; Martin; Moser; Philipp; Diehl

    2014-01-01

    Microparticles are small cell vesicles that can be released by almost all eukaryotic cells during cellular stress and cell activation. Within the last 1-2 decades it has been shown that microparticles are useful blood surrogate markers for different pathological conditions, such as vascular inflammation, coagulation and tumour diseases. Several studies have investigated the abundance of microparticles of different cellular origins in multiple cardiovascular diseases. It thereby has been shown that microparticles released by platelets, leukocytes and endothelial cells can be found in conditions of endothelial dysfunction, acute and chronic vascular inflammation and hypercoagulation. In addition to their function as surrogate markers, several studies indicate that circulating microparticles can fuse with distinct target cells, such as endothelial cells or leukocyte, and thereby deliver cellular components of their parental cells to the target cells. Hence, microparticles are a novel entity of circulating, paracrine, biological vectors which can influence the phenotype, the function and presumably even the transcriptome of their target cells.This review article aims to give a brief overview about the microparticle biology with a focus on endothelial activation and arterial hypertension. More detailed information about the role of microparticles in pathophysiology and disease can be found in already published work.

  13. Flow cytometric assessment of circulating platelet and erythrocytes microparticles in young thalassemia major patients: relation to pulmonary hypertension and aortic wall stiffness.

    Science.gov (United States)

    Tantawy, Azza A G; Adly, Amira A M; Ismail, Eman A R; Habeeb, Nevin M

    2013-06-01

    Heart disease is the leading cause of mortality and morbidity in β-thalassemia major (β-TM). Aggregability of abnormal red cells and membrane-derived microparticles (MPs) stemming from activated platelets and erythrocytes are responsible for thrombotic risk. We measured platelet and erythrocyte MPs (PMPs and ErMPs) in 60 young β-TM patients compared with 40 age- and sex-matched healthy controls and assessed their relation to clinicopathological characteristics and aortic elastic properties. Patients were studied stressing on transfusion history, splenectomy, thrombotic events, chelation therapy, hematological and coagulation profiles, flow cytometric measurement of PMPs (CD41b(+) ) and ErMPs (glycophorin A(+) ) as well as echocardiographic assessment of aortic elastic properties. Aortic stiffness index and pulmonary artery pressure were significantly higher, whereas aortic strain and distensibility were lower in TM patients than controls (P 2500 μg/L (P < 0.001). Compliant patients on chelation therapy had lower MPs levels than non-compliant patients (P < 0.001). PMPs and ErMPs were positively correlated to markers of hemolysis, serum ferritin, D-dimer, vWF Ag, and aortic stiffness, whereas negatively correlated to hemoglobin level and aortic distensibility (P < 0.05). We suggest that increased MPs may be implicated in vascular dysfunction, pulmonary hypertension risk, and aortic wall stiffness observed in thalassemia patients. Their quantification could provide utility for early detection of cardiovascular abnormalities and monitoring the biological efficacy of chelation therapy.

  14. Physics of microparticle acoustophoresis

    DEFF Research Database (Denmark)

    Barnkob, Rune

    2012-01-01

    of microparticle acoustophoresis and to develop methods for future advancement of its use. Throughout the work on this thesis the author and co-workers1 have studied the physics of microparticle acoustophoresis by comparing quantitative measurements to a theoretical framework consisting of existing hydrodynamic...

  15. Cardiac protective role of a novel erythrocyte-derived depressing factor on rats and its Ca2+ mechanism

    Institute of Scientific and Technical Information of China (English)

    WANG Yutang; WEN Yunyi; MA Ning; SHI Lei

    2003-01-01

    The cardiac protective role of a novel erythrocyte-derived depressing factor (EDDF) on spontaneous hypertensive rats (SHR), calcium overload (CaO) rats and Wistar rats and its mechanism was evaluated. Mean artery pressure (MAP), heart rate (HR) and LVdp/dtmax were measured by physiological recorder. The effect of EDDF on the Ca2+-ATPase activity in myocardial sarcoplasmic reticulum (SR) of CaO rats was determined by inorganic phosphate assay. Calcium transport in myocytes was measured by 45Ca2+ radioactive isotope measurement. The phosphorylation levels of extracellular signal-regulated protein kinases (ERK1/2) in myocardial tissue of SHR and CaO rats were measured by Western blot method. And the ultrastructures of cardiac muscle cells were observed with the transmission electron microscope. The results indicated that EDDF could significantly decrease MAP, HR and LVdp/dtmax in a dose dependent manner (P < 0.05). It seems that the mechanism might relate with activating the Ca2+-APTase, enhancing the uptake and release of Ca2+ from SR (P < 0.05), decreasing the phosphorylation levels of ERK1/2 of myocytes (P < 0.01) and lightening the ultrastructural lesion of cardiac muscle cells. In CaO rats, the Ca2+-ATPase activity decreased clearly compared to control (64.99 ± 7.16 vs 94.48 ± 7.68 nmol·min-1·mg-1 protein, P < 0.01), while EDDF (100 μg/mL) could significantly increase the activity (87.93 ± 9.54 vs 64.99 ± 7.16, P < 0.05, n = 7). Both uptake and release rate of Ca2+ (μmol 45Ca2+/g protein/min) from myocardial SR of CaO rats remarkably decreased compared to control (32.40 ± 2.70 and 15.46 ± 1.49 vs 61.09 ± 10.89 and 25.47 ± 4.29, P < 0.05); EDDF (100 μg/mL) could significantly stimulate their activities (50.48 ± 6.76 and 21.76 ± 2.75 vs 32.40 ± 2.70 and 15.46 ± 1.49, P < 0.05). EDDF could evidently down-regulate the phosphorylation of ERK1/2 in myocardial tissue from SHR and CaO rats (P < 0.01), lighten the ultrastructural lesion of cardiac muscle

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

    Science.gov (United States)

    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.

  17. Microparticles engineered to highly express peroxisome proliferator-activated receptor-γ decreased inflammatory mediator production and increased adhesion of recipient monocytes.

    Directory of Open Access Journals (Sweden)

    Julie Sahler

    Full Text Available Circulating blood microparticles are submicron vesicles released primarily by megakaryocytes and platelets that act as transcellular communicators. Inflammatory conditions exhibit elevated blood microparticle numbers compared to healthy conditions. Direct functional consequences of microparticle composition, especially internal composition, on recipient cells are poorly understood. Our objective was to evaluate if microparticle composition could impact the function of recipient cells, particularly during inflammatory provocation. We therefore engineered the composition of megakaryocyte culture-derived microparticles to generate distinct microparticle populations that were given to human monocytes to assay for influences recipient cell function. Herein, we tested the responses of monocytes exposed to either control microparticles or microparticles that contain the anti-inflammatory transcription factor, peroxisome proliferator-activated receptor-γ (PPARγ. In order to normalize relative microparticle abundance from two microparticle populations, we implemented a novel approach that utilizes a Nanodrop Spectrophotometer to assay for microparticle density rather than concentration. We found that when given to peripheral blood mononuclear cells, microparticles were preferentially internalized by CD11b+ cells, and furthermore, microparticle composition had a profound functional impact on recipient monocytes. Specifically, microparticles containing PPARγ reduced activated monocyte production of the proinflammatory cytokines interleukin-8 and monocyte chemotactic protein-1 compared to activated monocytes exposed to control microparticles. Additionally, treatment with PPARγ microparticles greatly increased monocyte cell adherence. This change in morphology occurred simultaneously with increased production of the key extracellular matrix protein, fibronectin and increased expression of the fibronectin-binding integrin, ITGA5. PPARγ microparticles

  18. Characterization of blood borne microparticles as markers of premature coronary calcification in newly menopausal women

    OpenAIRE

    Jayachandran, Muthuvel; Litwiller, Robert D.; Owen, Whyte G.; Heit, John A.; Behrenbeck, Thomas; Mulvagh, Sharon L.; Araoz, Philip A; Budoff, Matthew J.; Harman, S. Mitchell; Virginia M Miller

    2008-01-01

    While the risk for symptomatic atherosclerotic disease increases after menopause, currently recognized risk factors do not identify ongoing disease processes in low-risk women. This study tested the hypothesis that circulating cell-derived microparticles may reflect disease processes in women defined as low risk by the Framingham risk score. The concentration and phenotype of circulating microparticles were evaluated in a cross-sectional study of apparently healthy menopausal women, screened ...

  19. Characterization of blood borne microparticles as markers of premature coronary calcification in newly menopausal women

    Science.gov (United States)

    Jayachandran, Muthuvel; Litwiller, Robert D.; Owen, Whyte G.; Heit, John A.; Behrenbeck, Thomas; Mulvagh, Sharon L.; Araoz, Philip A.; Budoff, Matthew J.; Harman, S. Mitchell; Miller, Virginia M.

    2008-01-01

    While the risk for symptomatic atherosclerotic disease increases after menopause, currently recognized risk factors do not identify ongoing disease processes in low-risk women. This study tested the hypothesis that circulating cell-derived microparticles may reflect disease processes in women defined as low risk by the Framingham risk score. The concentration and phenotype of circulating microparticles were evaluated in a cross-sectional study of apparently healthy menopausal women, screened for enrollment into the Kronos Early Estrogen Prevention Study. Microparticles were evaluated by flow cytometry, and coronary artery calcification (CAC) was scored using 64-slice computed tomography scanners. The procoagulant activity of isolated microparticles was determined with a sensitive fluorescent thrombin generation assay. Chronological age, body mass index, serum lipids, systolic blood pressure (Framingham risk score 50; range, 93–315 Agatston units) CAC compared with women without calcification. The total concentration and percentage of microparticles derived from platelets and endothelial cells were greatest in women with high CAC scores. The thrombin-generating capacity of the isolated microparticles correlated with phosphatidylserine expression, which also was greatest in women with high CAC scores. The percentages of microparticles expressing granulocyte and monocyte markers were not significantly different among groups. Therefore, the characterization of platelet and endothelial microparticles may identify early menopausal women with premature CAC who would not otherwise be identified by the usual risk factor analysis. PMID:18621859

  20. Nanosized blood microparticles

    NARCIS (Netherlands)

    Yuana, Yuana

    2011-01-01

    Microparticles (MPs) have important physiological and pathological roles in blood coagulation, inflammation and tumor progression. In recent years MPs also have been recognized to participate in important biological processes, such as in signaling and in the horizontal transfer of their specific pro

  1. Phospholipid Binding Protein C Inhibitor (PCI Is Present on Microparticles Generated In Vitro and In Vivo.

    Directory of Open Access Journals (Sweden)

    Katrin Einfinger

    Full Text Available Protein C inhibitor is a secreted, non-specific serine protease inhibitor with broad protease reactivity. It binds glycosaminoglycans and anionic phospholipids, which can modulate its activity. Anionic phospholipids, such as phosphatidylserine are normally localized to the inner leaflet of the plasma membrane, but are exposed on activated and apoptotic cells and on plasma membrane-derived microparticles. In this report we show by flow cytometry that microparticles derived from cultured cells and activated platelets incorporated protein C inhibitor during membrane blebbing. Moreover, protein C inhibitor is present in/on microparticles circulating in normal human plasma as judged from Western blots, ELISAs, flow cytometry, and mass spectrometry. These plasma microparticles are mainly derived from megakaryocytes. They seem to be saturated with protein C inhibitor, since they do not bind added fluorescence-labeled protein C inhibitor. Heparin partially removed microparticle-bound protein C inhibitor, supporting our assumption that protein C inhibitor is bound via phospholipids. To assess the biological role of microparticle-bound protein C inhibitor we performed protease inhibition assays and co-precipitated putative binding partners on microparticles with anti-protein C inhibitor IgG. As judged from amidolytic assays microparticle-bound protein C inhibitor did not inhibit activated protein C or thrombin, nor did microparticles modulate the activity of exogenous protein C inhibitor. Among the proteins co-precipitating with protein C inhibitor, complement factors, especially complement factor 3, were most striking. Taken together, our data do not support a major role of microparticle-associated protein C inhibitor in coagulation, but rather suggest an interaction with proteins of the complement system present on these phospholipid vesicles.

  2. A heparin-based method for flow cytometric analysis of microparticles directly from platelet-poor plasma in calcium containing buffer

    DEFF Research Database (Denmark)

    Iversen, Line V; Ostergaard, Ole; Nielsen, Christoffer;

    2013-01-01

    Characterization of circulating microparticles (MPs) is usually performed by flow cytometry. Annexin V, a protein that Ca(2+)-dependently binds to phosphatidylserine, has been used to define entire microparticle (MP) populations, but not all MPs bind AnxV. Recent reports have correlated AnxV nega...

  3. Fabrication of hydrophilic paclitaxel-loaded PLA-PEG-PLA microparticles via SEDS process

    Institute of Scientific and Technical Information of China (English)

    Ping OUYANG; Yun-qing KANG; Guang-fu YIN; Zhong-bing HUANG; Ya-dong YAO; Xiao-ming LIAO

    2009-01-01

    In this work, chemically bonded poly(D, L-lactide)-polyethylene glycol-poly(D, L-lactide) (PLA-PEG-PLA) triblock copolymers with various PEG contents and PLA homopolymer were synthesized via melt polymerization, and were confirmed by FTIR and 1 H-NMR results. The molecular weight and polydispersity of the synthesized PLA and PLA-PEG-PLA copolymers were investigated by gel permeation chromatography. Hydro-philicity of the copolymers was identified by contact angle measurement. PLA-PEG-PLA and PLA microparticles loaded with and without PTX were then produced via solution enhanced dispersion by supercritical CO2 (SEDS) process. The effect of the PEG content on the particle size distribution, morphology, drug load, and encapsulation efficiency of the fabricated microparticles was also studied. Results indicate that PLA and PLA-PEG-PLA micropar-ticles all exhibit sphere-like shape with smooth surface, when PEG content is relatively low. The produced microparticles have narrow particle size distributions and small particle sizes. The drug load and encapsulation efficiency of the produced microparticles decreases with higher PEG content in the copolymer matrix. Moreover, high hydrophilicity is found when PEG is chemically attached to originally hydrophobic PLA, providing the produced drug-loaded microparticles with high hydrophi-licity, biocompatibility, and prolonged circulation time, which are considered of vital importance for vessel-circulating drug delivery system.

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

    Directory of Open Access Journals (Sweden)

    Gemma Chiva-Blanch

    Full Text Available 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.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.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.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 after stroke. Larger

  5. Increased IgG on cell-derived plasma microparticles in systemic lupus erythematosus is associated with autoantibodies and complement activation

    DEFF Research Database (Denmark)

    Nielsen, Christoffer T; Østergaard, Ole; Stener, Line;

    2012-01-01

    To quantify immunoglobulin and C1q on circulating cell-derived microparticles (MPs) in patients with systemic lupus erythematosus (SLE) and to determine whether immunoglobulin and C1q levels are correlated with clinical and serologic parameters.......To quantify immunoglobulin and C1q on circulating cell-derived microparticles (MPs) in patients with systemic lupus erythematosus (SLE) and to determine whether immunoglobulin and C1q levels are correlated with clinical and serologic parameters....

  6. Pharmaceutical microparticle engineering with electrospraying

    DEFF Research Database (Denmark)

    Bohr, Adam; Wan, Feng; Kristensen, Jakob;

    2015-01-01

    Microparticles of Celecoxib, dispersed in a matrix of poly(lactic-co-glycolic acid) (PLGA), were prepared by electrospraying using different solvent mixtures to investigate the influence upon particle formation and the resulting particle characteristics. Mixtures consisting of a good solvent, ace...

  7. Microparticles as Potential Biomarkers of Cardiovascular Disease

    Energy Technology Data Exchange (ETDEWEB)

    França, Carolina Nunes, E-mail: carolufscar24@gmail.com [Universidade Federal de São Paulo - UNIFESP - UNISA, SP, São Paulo (Brazil); Universidade de Santo Amaro - UNISA, SP, São Paulo (Brazil); Izar, Maria Cristina de Oliveira; Amaral, Jônatas Bussador do; Tegani, Daniela Melo; Fonseca, Francisco Antonio Helfenstein [Universidade Federal de São Paulo - UNIFESP - UNISA, SP, São Paulo (Brazil)

    2015-02-15

    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.

  8. Microparticle formation after co-culture of human whole blood and umbilical artery in a novel in vitro model of flow.

    Science.gov (United States)

    Holtom, Emma; Usherwood, James R; Macey, Marion G; Lawson, Charlotte

    2012-05-01

    Cardiovascular disease (CVD) is now the largest killer in western society, and the importance of interactions between vascular endothelium and circulating blood components in disease pathogenesis is well established. Microparticles are a heterogeneous population of laminar flow conditions. Here we have investigated microparticle production after perfusion of human whole blood through intact inflamed human umbilical artery. When blood was perfused through umbilical arteries which had been pre-stimulated with tumour necrosis factor (TNFα) for 18 h under flow conditions, there was significantly increased production of microparticles from both platelet and non-platelet sources, in particular from erythrocytes. To determine whether microparticles generated during interactions with inflamed endothelium could induce a pro-inflammatory response in trans, we isolated microparticles by centrifugation after co-culture and incubated with isolated quiescent endothelial cells followed by measurement of reactive oxygen species formation. Microparticles derived from co-culture with inflamed endothelium induced significantly enhanced levels of reactive oxygen species (ROS). These data suggest that presence of an inflamed endothelium causes release of pro-inflammatory microparticles from circulating blood cells, which could contribute to prolonged endothelial activation and subsequent atherosclerotic changes in blood vessels subjected to inflammatory insult.

  9. Microparticles generated during chronic cerebral ischemia deliver proapoptotic signals to cultured endothelial cells

    Energy Technology Data Exchange (ETDEWEB)

    Schock, Sarah C. [Ottawa Hospital Research Institute, Neuroscience, 451 Smyth Road, Ottawa, ON K1H 8M5 (Canada); Edrissi, Hamidreza [University of Ottawa, Neuroscience Graduate Program, 451 Smyth Road, Ottawa, ON K1H 8M5 (Canada); Burger, Dylan [Ottawa Hospital Research Institute, Kidney Centre, 451 Smyth Road, Ottawa, ON K1H 8M5 (Canada); Cadonic, Robert; Hakim, Antoine [Ottawa Hospital Research Institute, Neuroscience, 451 Smyth Road, Ottawa, ON K1H 8M5 (Canada); Thompson, Charlie, E-mail: charliet@uottawa.ca [Ottawa Hospital Research Institute, Neuroscience, 451 Smyth Road, Ottawa, ON K1H 8M5 (Canada)

    2014-07-18

    Highlights: • Microparticles are elevated in the plasma in a rodent model of chronic cerebral ischemia. • These microparticles initiate apoptosis in cultured cells. • Microparticles contain caspase 3 and they activate receptors for TNF-α and TRAIL. - Abstract: Circulating microparticles (MPs) are involved in many physiological processes and numbers are increased in a variety of cardiovascular disorders. The present aims were to characterize levels of MPs in a rodent model of chronic cerebral hypoperfusion (CCH) and to determine their signaling properties. MPs were isolated from the plasma of rats exposed to CCH and quantified by flow cytometry. When MPs were added to cultured endothelial cells or normal rat kidney cells they induced cell death in a time and dose dependent manner. Analysis of pellets by electron microscopy indicates that cell death signals are carried by particles in the range of 400 nm in diameter or less. Cell death involved the activation of caspase 3 and was not a consequence of oxidative stress. Inhibition of the Fas/FasL signaling pathway also did not improve cell survival. MPs were found to contain caspase 3 and treating the MPs with a caspase 3 inhibitor significantly reduced cell death. A TNF-α receptor blocker and a TRAIL neutralizing antibody also significantly reduced cell death. Levels of circulating MPs are elevated in a rodent model of chronic cerebral ischemia. MPs with a diameter of 400 nm or less activate the TNF-α and TRAIL signaling pathways and may deliver caspase 3 to cultured cells.

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

    Science.gov (United States)

    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

  11. Endotoxin-induced monocytic microparticles have contrasting effects on endothelial inflammatory responses.

    Directory of Open Access Journals (Sweden)

    Beryl Wen

    Full Text Available Septic shock is a severe disease state characterised by the body's life threatening response to infection. Complex interactions between endothelial cells and circulating monocytes are responsible for microvasculature dysfunction contributing to the pathogenesis of this syndrome. Here, we intended to determine whether microparticles derived from activated monocytes contribute towards inflammatory processes and notably vascular permeability. We found that endotoxin stimulation of human monocytes enhances the release of microparticles of varying phenotypes and mRNA contents. Elevated numbers of LPS-induced monocytic microparticles (mMP expressed CD54 and contained higher levels of transcripts for pro-inflammatory cytokines such as TNF, IL-6 and IL-8. Using a prothrombin time assay, a greater reduction in plasma coagulation time was observed with LPS-induced mMP than with non-stimulated mMP. Co-incubation of mMP with the human brain endothelial cell line hCMEC/D3 triggered their time-dependent uptake and significantly enhanced endothelial microparticle release. Unexpectedly, mMP also modified signalling pathways by diminishing pSrc (tyr416 expression and promoted endothelial monolayer tightness, as demonstrated by endothelial impedance and permeability assays. Altogether, these data strongly suggest that LPS-induced mMP have contrasting effects on the intercellular communication network and display a dual potential: enhanced pro-inflammatory and procoagulant properties, together with protective function of the endothelium.

  12. Cellular origin of platelet-derived microparticles in vivo

    NARCIS (Netherlands)

    A. Rank; R. Nieuwland; R. Delker; A. Köhler; B. Toth; V. Pihusch; R. Wilkowski; R. Pihusch

    2010-01-01

    Introduction: Microparticles (MP), presumably of platelet origin, are the most abundant microparticles in blood. To which extent such MP may also directly originate from megakaryocytes, however, is unknown. During hematopoietic stem cell transplantation, patients undergo total body irradiation which

  13. CYTOTOXIC AND IMMUNOCHEMICAL PROPERTIES OF VISCUMIN ENCAPSULATED IN POLYLACTIDE MICROPARTICLES

    OpenAIRE

    Kolotova, E.; Egorova, S.; Ramonova, A.; Bogorodski, S.; Popov, V.; Agapov, I.; Kirpichnikov, M.

    2012-01-01

    Biodegradable polylactide microparticles with encapsulated cytotoxic protein viscumin were obtained via the ultrasound-assisted supercritical fluid technique. The size of the microparticles was 10–50 µM, as shown by electron microscopy. The time course of viscumin release from microparticles was studied using an immunoenzyme test system with anti-viscumin monoclonal antibodies. It was found that 99.91% of the cytotoxic protein was incorporated into polymer microparticles. Only 0.08% of the in...

  14. Influence of microparticle size on cavitation noise during ultrasonic vibration

    Directory of Open Access Journals (Sweden)

    H. Ge

    2015-09-01

    Full Text Available The cavitation noise in the ultrasonic vibration system was found to be influenced by the size of microparticles added in water. The SiO2 microparticles with the diameter smaller than 100 μm reduced the cavitation noise, and the reason was attributed to the constrained oscillation of the cavitation bubbles, which were stabilized by the microparticles.

  15. Fetal Circulation

    Science.gov (United States)

    ... Pressure High Blood Pressure Tools & Resources Stroke More Fetal Circulation Updated:Jul 8,2016 click to enlarge The ... fetal heart. These two bypass pathways in the fetal circulation make it possible for most fetuses to survive ...

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

    Science.gov (United States)

    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.

  17. Microparticles and Exosomes in Gynecologic Neoplasias

    NARCIS (Netherlands)

    R. Nieuwland; J.A.M. van der Post; C.A.R. Lok Gemma; G. Kenter; A. Sturk

    2010-01-01

    This review presents an overview of the functions of microparticles and exosomes in gynecologic neoplasias. Growing evidence suggests that vesicles released from cancer cells in gynecologic malignancies contribute to the hypercoagulable state of these patients and contribute to tumor progression by

  18. Diving with microparticles in acoustic fields

    DEFF Research Database (Denmark)

    Marin, Alvaro; Rossi, Massimiliano; Barnkob, Rune;

    2012-01-01

    Sound can move particles. A good example of this phenomenon is the Chladni plate, in which an acoustic wave is induced in a metallic plate and particles migrate to the nodes of the acoustic wave. For several years, acoustophoresis has been used to manipulate microparticles in microscopic scales...

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

    Science.gov (United States)

    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.

  20. Fabrication of dielectrophoretic microfluidic chips using a facile screen-printing technique for microparticle trapping

    Science.gov (United States)

    Wee, Wei Hong; Li, Zedong; Hu, Jie; Adib Kadri, Nahrizul; Xu, Feng; Li, Fei; Pingguan-Murphy, Belinda

    2015-10-01

    Trapping of microparticles finds wide applications in numerous fields. Microfluidic chips based on a dielectrophoresis (DEP) technique hold several advantages for trapping microparticles, such as fast result processing, a small amount of sample required, high spatial resolution, and high accuracy of target selection. There is an unmet need to develop DEP microfluidic chips on different substrates for different applications in a low cost, facile, and rapid way. This study develops a new facile method based on a screen-printing technique for fabrication of electrodes of DEP chips on three types of substrates (i.e. polymethyl-methacrylate (PMMA), poly(ethylene terephthalate) and A4 paper). The fabricated PMMA-based DEP microfluidic chip was selected as an example and successfully used to trap and align polystyrene microparticles in a suspension and cardiac fibroblasts in a cell culture solution. The developed electrode fabrication method is compatible with different kinds of DEP substrates, which could expand the future application field of DEP microfluidic chips, including new forms of point-of care diagnostics and trapping circulating tumor cells.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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

  3. The development of polycaprolactone microparticles; Desenvolvimento de microparticulas de policaprolactona

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2011-07-01

    The microparticles are a micrometric system formed by biocompatible and biodegradable polymeric materials. The polycaprolactone is a crystalline biopolyester and it is widely used in microparticles system. The spray drying is a simple, rapid and reproducible method, which allows the microparticles development. The aim of this study was the development of polycaprolactone microparticles, using the spray drying technique, and their characterization by transmission electron microscopy, infrared spectroscopy, X-ray diffraction and dynamic light scattering. Three samples were developed: Polycaprolactone without ultra turrax homogenization, polycaprolactone with ultra turrax homogenization and Polycaprolactone with ultra turrax homogenization and NT-25 nanoclay. After that, all the samples were taken to the spray drying. Microparticles showed a concave morphology and they were amorphous. The NT-25 nanoclay reduced the microparticles size. (author)

  4. Therapeutic Strategies Based on Polymeric Microparticles

    Directory of Open Access Journals (Sweden)

    C. Vilos

    2012-01-01

    Full Text Available 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.

  5. Nearshore circulation

    NARCIS (Netherlands)

    Battjes, J.A.; Sobey, R.J.; Stive, M.J.F.

    1990-01-01

    Shelf circulation is driven primarily by wind- and tide-induced forces. It is laterally only weakly constrained so that the geostrophic (Coriolis) acceleration is manifest in the response. Nearshore circulation on the other hand is dominated by wave-induced forces associated with shallow-water. wave

  6. Porphyrin Microparticles for Biological and Biomedical Applications

    Science.gov (United States)

    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.

  7. Inhibition of platelet activation prevents the P-selectin and integrin-dependent accumulation of cancer cell microparticles and reduces tumor growth and metastasis in vivo.

    Science.gov (United States)

    Mezouar, Soraya; Darbousset, Roxane; Dignat-George, Françoise; Panicot-Dubois, Laurence; Dubois, Christophe

    2015-01-15

    Venous thromboembolism constitutes one of the main causes of death during the progression of a cancer. We previously demonstrated that tissue factor (TF)-bearing cancer cell-derived microparticles accumulate at the site of injury in mice developing a pancreatic cancer. The presence of these microparticles at the site of thrombosis correlates with the size of the platelet-rich thrombus. The objective of this study was to determine the involvement of TF expressed by cancer cell-derived microparticles on thrombosis associated with cancer. We observed that pancreatic cancer cell derived microparticles expressed TF, its inhibitor tissue factor pathway inhibitor (TFPI) as well as the integrins αvβ1 and αvβ3. In mice bearing a tumor under-expressing TF, a significant decrease in circulating TF activity associated with an increase bleeding time and a 100-fold diminished fibrin generation and platelet accumulation at the site of injury were observed. This was mainly due to the interaction of circulating cancer cell-derived microparticles expressing TFPI with activated platelets and fibrinogen. In an ectopic model of cancer, treatment of mice with Clopidogrel, an anti-platelet drug, decreased the size of the tumors and restored hemostasis by preventing the accumulation of cancer cell-derived microparticles at the site of thrombosis. In a syngeneic orthotopic model of pancreatic cancer Clopidogrel also significantly inhibited the development of metastases. Together, these results indicate that an anti-platelet strategy may efficiently treat thrombosis associated with cancer and reduce the progression of pancreatic cancer in mice.

  8. Anti-β2GPI antibodies stimulate endothelial cell microparticle release via a nonmuscle myosin II motor protein-dependent pathway.

    Science.gov (United States)

    Betapudi, Venkaiah; Lominadze, George; Hsi, Linda; Willard, Belinda; Wu, Meifang; McCrae, Keith R

    2013-11-28

    The antiphospholipid syndrome is characterized by thrombosis and recurrent fetal loss in patients with antiphospholipid antibodies (APLAs). Most pathogenic APLAs are directed against β2-glycoprotein I (β2GPI), a plasma phospholipid binding protein. One mechanism by which circulating antiphospholipid/anti-β2GPI antibodies may promote thrombosis is by inducing the release of procoagulant microparticles from endothelial cells. However, there is no information available concerning the mechanisms by which anti-β2GPI antibodies induce microparticle release. In seeking to identify proteins phosphorylated during anti-β2GPI antibody-induced endothelial activation, we observed phosphorylation of nonmuscle myosin II regulatory light chain (RLC), which regulates cytoskeletal assembly. In parallel, we observed a dramatic increase in the formation of filamentous actin, a two- to fivefold increase in the release of endothelial cell microparticles, and a 10- to 15-fold increase in the expression of E-selectin, intercellular adhesion molecule 1, vascular cell adhesion molecule 1, and tissue factor messenger RNA. Microparticle release, but not endothelial cell surface E-selectin expression, was blocked by inhibiting RLC phosphorylation or nonmuscle myosin II motor activity. These results suggest that distinct pathways, some of which mediate cytoskeletal assembly, regulate the endothelial cell response to anti-β2GPI antibodies. Inhibition of nonmuscle myosin II activation may provide a novel approach for inhibiting microparticle release by endothelial cells in response to anti-β2GPI antibodies. PMID:23954892

  9. Microparticles: A New Perspective in Central Nervous System Disorders

    Directory of Open Access Journals (Sweden)

    Stephanie M. Schindler

    2014-01-01

    Full Text Available 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.

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

    Directory of Open Access Journals (Sweden)

    Liron Issman

    Full Text Available 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.

  11. Evaluating conditions for the formation of chitosan/gelatin microparticles

    Directory of Open Access Journals (Sweden)

    Marcia C. Silva

    2009-06-01

    Full Text Available Chitosan/gelatin microparticles were prepared by complex coacervation. Three chitosan (CH samples, with different acetylation degrees and intrinsic viscosities, were used together with commercial gelatin (G samples. Microparticles formation was investigated at various CH/G ratios, within the pH range of 3.5 to 6.0. Reactions were carried out at 40 and 60 ºC, for 2, 4, and 6 hours. Turbidity measurements performed at 633 nm were used to monitor the process. The resulting curves revealed maximum values, which were correlated to the glucosamine content of CH samples. After isolation, yields were determined, and the microparticles were characterized by infrared spectroscopy (FTIR and thermogravimetry (TGA. Both techniques evidenced the formation of coacervate microparticles. The highest yields in microparticles were determined for the system comprising the CH sample with the lowest degree of acetylation and intrinsic viscosity, and the gelatin sample with the lowest bloom strength.

  12. PREPARATION AND CHARACTERIZATION OF SUPERPARAMAGNETIC FUNCTIONAL POLYMERIC MICROPARTICLES

    Institute of Scientific and Technical Information of China (English)

    Xianqiao Liu; Huizhou Liu; Jianmin Xing; Yueping Guan; Zhiya Ma; Guobin Shan; Chengli Yang

    2003-01-01

    Superparamagnetic poly(styrene-divinylbenzene-glycidyl methacrylate) (Pst-DVB-GMA) microparticles were prepared via a modified suspension polymerization process. A magnetic fluid was first prepared by a chemical co-precipitation method. Then magnetic microparticles were produced by mixing the monomers and the magnetic fluid with water in the presence of a stabilizer poly(vinyl pyrrolidone) (PVP) to form a suspension, and finally benzoyl peroxide was added to initiate the co-polymerization. The morphology and magnetic properties of the microparticles were examined by TEM and VSM. The spherically shaped microparticles, with a size range of 4 to 7 μm, showed distinct superparamagnetic characteristics. XRD was used to investigate the structure of the magnetite particles dispersed in the polymer matrix. The microparticles with epoxy groups on their surface can be applied directly to the separation of biomolecules.

  13. Froth flotation via microparticle stabilized foams

    International Nuclear Information System (INIS)

    There is a still growing interest in the recovery of rare earth elements due to their manifold industrial and technological applications. We present here a simple and effective method for the enrichment of micrometer sized La2O3 particles via microparticle stabilized foams. By using the short chain amphiphile (1-hexyl)trimethylammonium bromide (C6TAB) foam that is generated by surface modified particles only can be generated. This technique allows a more selective and specific particle transport mechanism. The results are discussed in terms of surface charges and transport mechanisms. Furthermore, the effects of particle concentration, pH and amphiphile concentration are studied and evaluated. (authors)

  14. Measurement of refractive index of single microparticles

    CERN Document Server

    Knoener, G; Nieminen, T A; Heckenberg, N R; Rubinsztein-Dunlop, H; Knoener, Gregor; Parkin, Simon; Nieminen, Timo A.; Heckenberg, Norman R.; Rubinsztein-Dunlop, Halina

    2006-01-01

    The refractive index of single microparticles is derived from precise measurement and rigorous modeling of the stiffness of a laser trap. We demonstrate the method for particles of four different materials with diameters from 1.6 to 5.2 microns and achieve an accuracy of better than 1%. The method greatly contributes as a new characterization technique because it works best under conditions (small particle size, polydispersion) where other methods, such as absorption spectroscopy, start to fail. Particles need not be transferred to a particular fluid, which prevents particle degradation or alteration common in index matching techniques. Our results also show that advanced modeling of laser traps accurately reproduces experimental reality.

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

    OpenAIRE

    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 prepar...

  16. Anti-neutrophil cytoplasmic antibodies stimulate release of neutrophil microparticles.

    LENUS (Irish Health Repository)

    Hong, Ying

    2012-01-01

    The mechanisms by which anti-neutrophil cytoplasmic antibodies (ANCAs) may contribute to the pathogenesis of ANCA-associated vasculitis are not well understood. In this study, both polyclonal ANCAs isolated from patients and chimeric proteinase 3-ANCA induced the release of neutrophil microparticles from primed neutrophils. These microparticles expressed a variety of markers, including the ANCA autoantigens proteinase 3 and myeloperoxidase. They bound endothelial cells via a CD18-mediated mechanism and induced an increase in endothelial intercellular adhesion molecule-1 expression, production of endothelial reactive oxygen species, and release of endothelial IL-6 and IL-8. Removal of the neutrophil microparticles by filtration or inhibition of reactive oxygen species production with antioxidants abolished microparticle-mediated endothelial activation. In addition, these microparticles promoted the generation of thrombin. In vivo, we detected more neutrophil microparticles in the plasma of children with ANCA-associated vasculitis compared with that in healthy controls or those with inactive vasculitis. Taken together, these results support a role for neutrophil microparticles in the pathogenesis of ANCA-associated vasculitis, potentially providing a target for future therapeutics.

  17. Review: the Multiple Roles of Monocytic Microparticles.

    Science.gov (United States)

    Halim, Ahmad Tarmizi Abdul; Ariffin, Nur Azrah Fazera Mohd; Azlan, Maryam

    2016-08-01

    Monocytic microparticles (mMP) are microparticles derived from human monocytes either under in vivo or in vitro conditions. The size of mMP is between 0.1 and 1.0 μm. Apart from the size range, mMPs are also identified based on phosphatidylserine and CD14 expression on their surface, though this is not always the case. Monocytic MP are critical players in inflammation, endothelial cell function, and blood coagulation. They exhibit dual function by either helping the progression of such conditions or limiting it, depending on certain factors. Furthermore, the numbers of mMP are elevated in some autoimmune diseases, infectious diseases, and metabolic disorders. However, it is unknown whether mMP play an active role in these diseases or are simply biomarkers. The mechanism of mMP modulation is yet to be identified. In this review, we highlight the mechanism of mMP formation and the roles that they play in inflammation, blood coagulation, and different disease settings. PMID:27216803

  18. Sedimentation behavior of indoor airborne microparticles

    Institute of Scientific and Technical Information of China (English)

    LI Ming; WU Chao; PAN Wei

    2008-01-01

    Experiments on the behavior of airborne microparticle sediments and their adhesion on glass slides were conducted in a laboratory located on the first floor of a teaching building. Clean tiles and glass slides were placed at different angles (0°, 45° and 90°) with respect to the horizontal plane in the laboratory. The sedimentation of microparticles was investigated at certain time intervals (1 d, 3 d, 10 d and 30 d). The results of testing, at day 30, show that the diameters of particles on the horizontal tiles varied from 20 to 80 μm; few particles with diameter less than 0.5 μm or greater than 100 μm were found. The amount of particle sediment on all the slides increased along over time, while the average diameter of particles was not correlated with time, nor with the angle of placement. The maximum particle size, the total particle surface area, the total perimeter of all particles and the cover ratio of light (the proportion of total area of particles to the observed area of the slides surfaces) did not change significantly within the first 10 days. Inspection of all the samples for the last 20 days, however, showed that these variables increased substantially with the passage of time and were in reverse proportion to the placement angles, which indicates a concentration of particles, as well as physical and chemical changes.

  19. Microfluidics assisted generation of innovative polysaccharide hydrogel microparticles.

    Science.gov (United States)

    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

  20. Circulation economics

    DEFF Research Database (Denmark)

    Ingebrigtsen, Stig; Jakobsen, Ove

    2006-01-01

    presupposes a perspective integrating economic, natural and cultural values. Third, to organize the interplay between all stakeholders we introduce an arena for communicative cooperation. Originality/value - The paper concludes that circulation economics presupposes a change in paradigm, from a mechanistic...

  1. Multifunctional Hydrogel Microparticles by Polymer-Assisted Photolithography.

    Science.gov (United States)

    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. PMID:26821173

  2. Hyperphosphatemia, Phosphoprotein Phosphatases, and Microparticle Release in Vascular Endothelial Cells.

    Science.gov (United States)

    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

  3. Release of Intracoronary Microparticles during Stent Implantation into Stable Atherosclerotic Lesions under Protection with an Aspiration Device.

    Directory of Open Access Journals (Sweden)

    Patrick Horn

    Full Text Available Stent implantation into atherosclerotic coronary vessels impacts on downstream microvascular function and induces the release of particulate debris and soluble substances, which differs qualitatively and quantitatively between native right coronary arteries (RCAs and saphenous vein grafts on right coronary arteries (SVG-RCAs. We have now quantified the release of microparticles (MPs during stent implantation into stable atherosclerotic lesions and compared the release between RCAs and SVG-RCAs.In symptomatic, male patients with stable angina and a stenosis in their RCA or SVG-RCA, respectively (n = 14/14, plaque volume and composition were analyzed using intravascular ultrasound before stent implantation. Coronary aspirate was retrieved during stent implantation with a distal occlusion/aspiration device and divided into particulate debris and plasma. Particulate debris was weighed. Platelet-derived MPs (PMPs were distinguished by flow cytometry as CD41+, endothelium-derived MPs (EMPs as CD144+, CD62E+ and CD31+/CD41-, leukocyte-derived MPs as CD45+, and erythrocyte-derived MPs as CD235+.In patients with comparable plaque volume and composition in RCAs and SVG-RCAs, intracoronary PMPs and EMPs were increased after stent implantation into their RCAs and SVG-RCAs (CD41+: 2729.6 ± 645.6 vs. 4208.7 ± 679.4 and 2355.9 ± 503.9 vs. 3285.8 ± 733.2 nr/µL; CD144+: 451.5 ± 87.9 vs. 861.7 ± 147.0 and 444.6 ± 74.8 vs. 726.5 ± 136.4 nr/µL; CD62E+: 1404.1 ± 247.7 vs. 1844.3 ± 378.6 and 1084.6 ± 211.0 vs. 1783.8 ± 384.3 nr/µL, P < 0.05, but not different between RCAs and SVG-RCAs.Stenting in stable atherosclerotic lesions is associated with a substantial release not only of PMPs, but also of EMPs in RCAs and SVG-RCAs. Their release does not differ between RCAs and SVG-RCAs.ClinicalTrials.gov NCT01430884.

  4. Analysis of micro-particles in TRISTAN vacuum chambers

    International Nuclear Information System (INIS)

    Micro-particles in the beam chamber of a TRISTAN vacuum system were investigated from the point of view of suppressing micro-particles trapped in the accumulation ring. Micro-particles coming from ion pumps (IP) and distributed ion pumps (DIP), aluminium alloy particles produced during treatment of aluminium alloy chambers for welding, micro-particles from the environment, i.e.soil (granite rocks or amphiboles), particles of concrete and painting materials were identified. A molten iron particle found in a chamber suggests interaction between the particle and bunched electron beam. Most of the particles coming from outside the chambers can be avoided by using high class clean rooms. The particles from the ion pumps can be reduced using different pumps which do not emit particles. The particles produced during assembly of, for example, DIP must be suppressed by accepting different assembling from the traditional ones. (author)

  5. Enhancement of laminar convective heat transfer using microparticle suspensions

    Science.gov (United States)

    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.

  6. Photophysical characterization of cumarin-doped poly (lactic acid) microparticles and visualization of the biodistribution

    International Nuclear Information System (INIS)

    We prepared fluorescent coumarin dye-doped poly (acrylic acid) microparticles, which are well known as a biodegradable polyester, and the photophysical properties were characterized by scanning electron microscope, atomic force microscope and spectroscopic investigation. Spherical particles with diameters ranging from 0.5 to a few μm were obtained. Based on spectroscopic investigation, the internal environment was close to that of a polar solvent such as methanol, and the dyes were dispersed without aggregation inside the particles. The obtained particles were administered to a mouse through the tail vein, and the biodistribution was then observed after some organs were excited at 1-day and 1-week post-injection. The particles were accumulated in the organs, especially in the lung and spleen. After injection, the particles were trapped temporally in the lung, and then seemed to be transported to other organs by blood circulation. This tendency is similar to the biodistribution of TiO2 microparticles that we have reported previously.

  7. Photophysical characterization of cumarin-doped poly (lactic acid) microparticles and visualization of the biodistribution

    Energy Technology Data Exchange (ETDEWEB)

    Abe, Shigeaki, E-mail: sabe@den.hokudai.ac.j [Department of Biomedical Materials and Engineering, Graduate School of Dental Medicine, Hokkaido University, Kita 13, Nishi 7, Sapporo 060-8586 (Japan); Kiba, Takayuki; Hosokawa, Kiyotada; Nitobe, Satoru; Hirota, Takashi; Kobayashi, Hirohisa [Division of Biotechnology and Macromolecular Chemistry, Graduate School of Hokkaido University, Sapporo 060-8628 (Japan); Akasaka, Tsukasa; Uo, Motohiro; Kuboki, Yoshinori [Department of Biomedical Materials and Engineering, Graduate School of Dental Medicine, Hokkaido University, Kita 13, Nishi 7, Sapporo 060-8586 (Japan); Sato, Shin-Ichiro [Division of Biotechnology and Macromolecular Chemistry, Graduate School of Hokkaido University, Sapporo 060-8628 (Japan); Watari, Fumio [Department of Biomedical Materials and Engineering, Graduate School of Dental Medicine, Hokkaido University, Kita 13, Nishi 7, Sapporo 060-8586 (Japan); Rosca, Iosif D. [Faculty of Engineering and Computer Science, Concordia University, 1455 de Maisonneuve Blvd. W, Montreal, QC H3G 1M8 (Canada)

    2010-08-15

    We prepared fluorescent coumarin dye-doped poly (acrylic acid) microparticles, which are well known as a biodegradable polyester, and the photophysical properties were characterized by scanning electron microscope, atomic force microscope and spectroscopic investigation. Spherical particles with diameters ranging from 0.5 to a few {mu}m were obtained. Based on spectroscopic investigation, the internal environment was close to that of a polar solvent such as methanol, and the dyes were dispersed without aggregation inside the particles. The obtained particles were administered to a mouse through the tail vein, and the biodistribution was then observed after some organs were excited at 1-day and 1-week post-injection. The particles were accumulated in the organs, especially in the lung and spleen. After injection, the particles were trapped temporally in the lung, and then seemed to be transported to other organs by blood circulation. This tendency is similar to the biodistribution of TiO{sub 2} microparticles that we have reported previously.

  8. Dual coated microparticles for intestinal delivery of nimesulide

    OpenAIRE

    Khan, Shujaat A.; Ahmad, Mahmood; Murtaza, Ghulam; Aamir, Muhammad N.; Akhtar, Naveed

    2010-01-01

    Nimesulide was formulated as novel dual coated microparticles using chitosan (CTN) and ethyl cellulose (EC) as encapsulating materials for its improved delivery to the intestine and to prevent gastric irritation and increase patient compliance. The first coating was applied by chitosan using pH change method followed by second coating of ethyl cellulose using thermal change method. This process was analysed for its capability to produce microparticles of uniform size, good flowability, unifor...

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

    Science.gov (United States)

    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

  10. Method for producing nano-embedded microparticles

    DEFF Research Database (Denmark)

    2015-01-01

    (EN)The present invention relates to a rapid, high-throughput and continuous method for producing nano-embedded microparticles in powder form, thereby providing a cost- effective process which can be performed aseptically. The invention further relates to an apparatus for performing the method...... of the invention. (FR)La présente invention concerne un procédé rapide, à haut rendement et continu de production de nano-microparticules intégrées sous forme de poudre, ce qui permet d'obtenir un procédé économique qui peut être mis en oeuvre de manière aseptique. L'invention concerne, en outre, un appareil pour...

  11. Combined AC electroosmosis and dielectrophoresis for controlled rotation of microparticles.

    Science.gov (United States)

    Walid Rezanoor, Md; Dutta, Prashanta

    2016-03-01

    Electrorotation is widely used for characterization of biological cells and materials using a rotating electric field. Generally, multiphase AC electric fields and quadrupolar electrode configuration are needed to create a rotating electric field for electrorotation. In this study, we demonstrate a simple method to rotate dielectrophoretically trapped microparticles using a stationary AC electric field. Coplanar interdigitated electrodes are used to create a linearly polarized nonuniform AC electric field. This nonuniform electric field is employed for dielectrophoretic trapping of microparticles as well as for generating electroosmotic flow in the vicinity of the electrodes resulting in rotation of microparticles in a microfluidic device. The rotation of barium titanate microparticles is observed in 2-propanol and methanol solvent at a frequency below 1 kHz. A particle rotation rate as high as 240 revolutions per minute is observed. It is demonstrated that precise manipulation (both rotation rate and equilibrium position) of the particles is possible by controlling the frequency of the applied electric field. At low frequency range, the equilibrium positions of the microparticles are observed between the electrode edge and electrode center. This method of particle manipulation is different from electrorotation as it uses induced AC electroosmosis instead of electric torque as in the case of electrorotation. Moreover, it has been shown that a microparticle can be rotated along its own axis without any translational motion. PMID:27014394

  12. The role of microparticles in chronic obstructive pulmonary disease

    Directory of Open Access Journals (Sweden)

    Takahashi T

    2014-03-01

    Full Text Available Toru Takahashi,1–3 Hiroshi Kubo11Department of Advanced Preventive Medicine for Infectious Disease, Tohoku University Graduate School of Medicine, Sendai, Japan; 2Cellular and molecular lung biology research units, Institut de Recherches Cliniques de Montréal (IRCM, Montreal, Quebec, Canada; 3Department of Anesthesiology, Tohoku University Hospital, Sendai, JapanAbstract: 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

  13. Microparticles: Facile and High-Throughput Synthesis of Functional Microparticles with Quick Response Codes (Small 24/2016).

    Science.gov (United States)

    Ramirez, Lisa Marie S; He, Muhan; Mailloux, Shay; George, Justin; Wang, Jun

    2016-06-01

    Microparticles carrying quick response (QR) barcodes are fabricated by J. Wang and co-workers on page 3259, using a massive coding of dissociated elements (MiCODE) technology. Each microparticle can bear a special custom-designed QR code that enables encryption or tagging with unlimited multiplexity, and the QR code can be easily read by cellphone applications. The utility of MiCODE particles in multiplexed DNA detection and microtagging for anti-counterfeiting is explored. PMID:27306741

  14. Impact of Endothelial Microparticles on Coagulation, Inflammation, and Angiogenesis in Age-Related Vascular Diseases

    Directory of Open Access Journals (Sweden)

    Margaret Markiewicz

    2013-01-01

    Full Text Available Endothelial microparticles (EMPs are complex vesicular structures that originate from plasma membranes of activated or apoptotic endothelial cells. EMPs play a significant role in vascular function by altering the processes of inflammation, coagulation, and angiogenesis, and they are key players in the pathogenesis of several vascular diseases. Circulating EMPs are increased in many age-related vascular diseases such as coronary artery disease, peripheral vascular disease, cerebral ischemia, and congestive heart failure. Their elevation in plasma has been considered as both a biomarker and bioactive effector of vascular damage and a target for vascular diseases. This review focuses on the pleiotropic roles of EMPs and the mechanisms that trigger their formation, particularly the involvement of decreased estrogen levels, thrombin, and PAI-1 as major factors that induce EMPs in age-related vascular diseases.

  15. Clinical Significance of Tissue Factor-Exposing Microparticles in Arterial and Venous Thrombosis.

    Science.gov (United States)

    van Es, Nick; Bleker, Suzanne; Sturk, Auguste; Nieuwland, Rienk

    2015-10-01

    Microparticles (MP) are small extracellular vesicles (30-1,000 nm) that are released from activated cells or platelets. Exposure of negatively charged phospholipids and tissue factor (TF) renders MP procoagulant. Normal plasma levels of intravascular TF-exposing MP (TFMP) are low, but their number may rise in pathological conditions, including cancer and infectious disease. Emerging evidence indicates an important role for these circulating TFMP in the pathogenesis of thrombotic complications such as venous thromboembolism and disseminated intravascular coagulation, whereas their contribution to arterial thrombosis is less studied. Despite serious limitations of the currently available assays for measuring TFMP levels or the procoagulant activity associated with TFMP with respect to sensitivity and specificity, the scientific interest in TFMP is rapidly growing because their application as prognostic biomarkers for thrombotic complications is promising. Future advances in detection methods will likely provide more insight into TFMP and eventually improve their clinical utility. PMID:26408926

  16. Microparticles release by adipocytes act as "find-me" signals to promote macrophage migration.

    Directory of Open Access Journals (Sweden)

    Akiko Eguchi

    Full Text Available Macrophage infiltration of adipose tissue during weight gain is a central event leading to the metabolic complications of obesity. However, what are the mechanisms attracting professional phagocytes to obese adipose tissue remains poorly understood. Here, we demonstrate that adipocyte-derived microparticles (MPs are critical "find-me" signals for recruitment of monocytes and macrophages. Supernatants from stressed adipocytes stimulated the attraction of monocyte cells and primary macrophages. The activation of caspase 3 was required for release of these signals. Adipocytes exposed to saturated fatty acids showed marked release of MPs into the supernatant while common genetic mouse models of obesity demonstrate high levels of circulating adipocyte-derived MPs. The release of MPs was highly regulated and dependent on caspase 3 and Rho-associated kinase. Further analysis identified these MPs as a central chemoattractant in vitro and in vivo. In addition, intravenously transplanting circulating MPs from the ob/ob mice lead to activation of monocytes in circulation and adipose tissue of the wild type mice. These data identify adipocyte-derived MPs as novel "find me" signals that contributes to macrophage infiltration associated with obesity.

  17. Optical manipulation of microparticles and biological structures

    Science.gov (United States)

    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

  18. Kinetics of release of methylene blue immobilized in calcium alginate microparticles

    OpenAIRE

    Inal Bakhytkyzy; R. Ussenkyzy; D. Rahimbaeva

    2013-01-01

    The swelling kinetics of microparticles obtained with different concentrations of calcium chloride was studied to learn the ability of sodium alginate to gelation. To increase the effect of prolongation it is necessary to obtain microparticles with sustained release of drugs. For this purpose the drying kinetics of alginate microparticles was investigated. Also the kinetics of release of methylene blue immobilized in calcium alginate microparticles was studied. It was found that the release o...

  19. Microparticles as biomarkers of osteonecrosis of the hip in sickle cell disease

    NARCIS (Netherlands)

    Marsh, Anne; Schiffelers, Raymond; Kuypers, Frans; Larkin, Sandra; Gildengorin, Ginny; van Solinge, Wouter; Hoppe, Carolyn

    2015-01-01

    Osteonecrosis of the femoral head (ONFH) is a common complication of sickle cell disease (SCD). To examine the association between microparticles and ONFH in SCD, we compared plasma microparticle levels in 20 patients with and without ONFH. Microparticles were quantified using nanoparticle tracking

  20. Dielectrophoretic micropatterning with microparticle monolayers covalently linked to glass surfaces.

    Science.gov (United States)

    Suzuki, Masato; Yasukawa, Tomoyuki; Mase, Yoshiaki; Oyamatsu, Daisuke; Shiku, Hitoshi; Matsue, Tomokazu

    2004-12-01

    Two-dimensional micropatterns of microparticles were fabricated on glass substrates with negative dielectrophoretic force, and the patterned microparticles were covalently bound on the substrate via cross-linking agents. The line and grid patterns of microparticles were prepared using the repulsive force of negative dielectrophoresis (n-DEP). The template interdigitated microband array (IDA) electrodes (width and gap 50 mum) were incorporated into the dielectrophoretic patterning cell with a fluidic channel. The microstructures on the glass substrates with amino or sulfhydryl groups were immobilized with the cross-linking agents disuccinimidyl suberate (DSS) and m-maleimidobenzoyl-N-hydroxy-succinimide ester (MBS). Diaphorase (Dp), a flavoenzyme, was selectively attached on the patterned microparticles using the maleimide groups of MBS. The enzyme activity on the patterned particles was electrochemically characterized with a scanning electrochemical microscope (SECM) in the presence of NADH and ferrocenylmethanol as a redox mediator. The SECM images proved that Dp was selectively immobilized onto the surface of microparticles to maintain its catalytic activity. PMID:15568852

  1. Shape-tunable core-shell microparticles.

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

  3. RDX-based nanocomposite microparticles for significantly reduced shock sensitivity

    Energy Technology Data Exchange (ETDEWEB)

    Qiu Hongwei, E-mail: hqiu@stevens.edu [Department of Chemical Engineering and Materials Science, Stevens Institute of Technology, Hoboken, NJ 07030 (United States); Stepanov, Victor; Di Stasio, Anthony R. [U.S. Army - Armament Research, Development, and Engineering Center, Picatinny, NJ 07806 (United States); Chou, Tsengming; Lee, Woo Y. [Department of Chemical Engineering and Materials Science, Stevens Institute of Technology, Hoboken, NJ 07030 (United States)

    2011-01-15

    Cyclotrimethylenetrinitramine (RDX)-based nanocomposite microparticles were produced by a simple, yet novel spray drying method. The microparticles were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and high performance liquid chromatography (HPLC), which shows that they consist of small RDX crystals ({approx}0.1-1 {mu}m) uniformly and discretely dispersed in a binder. The microparticles were subsequently pressed to produce dense energetic materials which exhibited a markedly lower shock sensitivity. The low sensitivity was attributed to small crystal size as well as small void size ({approx}250 nm). The method developed in this work may be suitable for the preparation of a wide range of insensitive explosive compositions.

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

    Science.gov (United States)

    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.

  5. Characterization of spray dried bioadhesive metformin microparticles for oromucosal administration

    DEFF Research Database (Denmark)

    Sander, Camilla; Madsen, Katrine Dragsbæk; Hyrup, Birgitte;

    2013-01-01

    delivery systems are considered a promising approach as they facilitate a close contact between the drug and the oral mucosa. In this study, bioadhesive chitosan-based microparticles of metformin hydrochloride were prepared by spray drying aqueous dispersions with different chitosan:metformin ratios...... and chitosan grades with increasing molecular weights. A recently developed ex vivo flow retention model with porcine buccal mucosa was used to evaluate the bioadhesive properties of spray dried microparticles. An important outcome of this study was that microparticles with the desired metformin content could...... be prepared and analyzed using the ex vivo retention model. We observed an increase in metformin retention on porcine mucosa with increasing chitosan:metformin ratios, while no effect of increasing the chitosan molecular weight was found. Rheological characterization of feeds for spray drying was performed...

  6. Preparation and characterization of spray-dried oxidized cellulose microparticles.

    Science.gov (United States)

    Kumar, V; Kang, J; Yang, T

    2001-08-01

    The goal of this study was to investigate the feasibility of spray drying to produce microparticles of oxidized cellulose (OC), a biocompatible and bioresorbable polymer. OCs containing 7, 13, and 20 wt% carboxylic groups were converted into stable aqueous dispersions and then spray dried using a Yamoto G-32 spray dryer equipped with a standard fluid nozzle with an orifice of 406 microm. The following operating conditions were investigated: inlet temperature 140, 170, and 190 degrees C; feed rate 3, 6, and 9 mL/min; and atomization airpressure 0.5, 1, and 1.5 kg f/cm2. The amounts of OC used in feed were 1, 2.5, and 5%. OC microparticles produced under these conditions were shrunken spheres, ranging in size between 0.98+/-0.47 and 2.05+/-0.98 microm. The different operating conditions used had no significant effect on the size and shape of particles. The use of a water-soluble plasticizer (glycerin, polyethylene glycol 400, or polyethylene glycol 6000) in the dispersion yielded microparticles with a good sphericity and a smooth surface morphology, whereas no change in the shape or size of microparticles was noted with water-insoluble plasticizers, Triacetin and dibutyl phthalate. Powder X-ray diffraction and Fourier transform infrared spectral analyses of spray-dried microparticles showed no change in the solid-state structure of OC. In conclusion, results show that OC can be converted into stable aqueous dispersions and used to produce microparticles by spray drying. PMID:11485186

  7. Titanium Dioxide Nanofibers and Microparticles Containing Nickel Nanoparticles

    OpenAIRE

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

    2012-01-01

    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 nanofib...

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

    Directory of Open Access Journals (Sweden)

    Bashar Yafouz

    2014-04-01

    Full Text Available 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.

  9. Decellularized extracellular matrix microparticles as a vehicle for cellular delivery in a model of anastomosis healing.

    Science.gov (United States)

    Hoganson, David M; Owens, Gwen E; Meppelink, Amanda M; Bassett, Erik K; Bowley, Chris M; Hinkel, Cameron J; Finkelstein, Eric B; Goldman, Scott M; Vacanti, Joseph P

    2016-07-01

    Extracellular matrix (ECM) materials from animal and human sources have become important materials for soft tissue repair. Microparticles of ECM materials have increased surface area and exposed binding sites compared to sheet materials. Decellularized porcine peritoneum was mechanically dissociated into 200 µm microparticles, seeded with fibroblasts and cultured in a low gravity rotating bioreactor. The cells avidly attached and maintained excellent viability on the microparticles. When the seeded microparticles were placed in a collagen gel, the cells quickly migrated off the microparticles and through the gel. Cells from seeded microparticles migrated to and across an in vitro anastomosis model, increasing the tensile strength of the model. Cell seeded microparticles of ECM material have potential for paracrine and cellular delivery therapies when delivered in a gel carrier. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 1728-1735, 2016. PMID:26946064

  10. Nicotine–magnesium aluminum silicate microparticle surface modified with chitosan for mucosal delivery

    Energy Technology Data Exchange (ETDEWEB)

    Kanjanakawinkul, Watchara [Faculty of Pharmaceutical Sciences, Khon Kaen University, Khon Kaen 40002 (Thailand); Rades, Thomas [School of Pharmacy, University of Otago, Dunedin 9054 (New Zealand); Department of Pharmacy, Faculty of Health and Medical Sciences, University of Copenhagen, DK-2100 Copenhagen (Denmark); Puttipipatkhachorn, Satit [Department of Manufacturing Pharmacy, Faculty of Pharmacy, Mahidol University, Bangkok 10400 (Thailand); Pongjanyakul, Thaned, E-mail: thaned@kku.ac.th [Faculty of Pharmaceutical Sciences, Khon Kaen University, Khon Kaen 40002 (Thailand)

    2013-04-01

    Magnesium aluminum silicate (MAS), a negatively charged clay, and nicotine (NCT), a basic drug, can interact electrostatically to form microparticles. Chitosan (CS) was used for the surface modification of the microparticles, and a lyophilization method was used to preserve the original particle morphology. The microparticles were characterized in terms of their physicochemical properties, NCT content, mucoadhesive properties, and release and permeation across porcine esophageal mucosa. The results showed that the microparticles formed via electrostatic interaction between MAS and protonated NCT had an irregular shape and that their NCT content increased with increasing NCT ratios in the microparticle preparation solution. High molecular weight CS (800 kDa) adsorbed to the microparticle surface and induced a positive surface charge. CS molecules intercalated into the MAS silicate layers and decreased the crystallinity of the microparticles, leading to an increase in the release rate and diffusion coefficient of NCT from the microparticles. Moreover, the microparticle surface modified with CS was found to have higher NCT permeation fluxes and mucoadhesive properties, which indicated the significant role of CS for NCT mucosal delivery. However, the enhancement of NCT permeation and of mucoadhesive properties depended on the molecular weight and concentration of CS. These findings suggest that NCT-MAS microparticle surface modified with CS represents a promising mucosal delivery system for NCT. Highlights: ► Nicotine–magnesium aluminum silicate microparticles were prepared using electrostatic interaction. ► Lyophilization was used for drying and maintaining an original morphology of the microparticles. ► Chitosan (CS) was used for surface modification of the microparticles at acidic pH. ► Surface modification using CS caused an increase in release and permeation of nicotine. ► Microparticle surface-modified with CS presented better mucoadhesive properties.

  11. "Kill" the messenger: Targeting of cell-derived microparticles in lupus nephritis.

    Science.gov (United States)

    Nielsen, Christoffer T; Rasmussen, Niclas S; Heegaard, Niels H H; Jacobsen, Søren

    2016-07-01

    Immune complex (IC) deposition in the glomerular basement membrane (GBM) is a key early pathogenic event in lupus nephritis (LN). The clarification of the mechanisms behind IC deposition will enable targeted therapy in the future. Circulating cell-derived microparticles (MPs) have been proposed as major sources of extracellular autoantigens and ICs and triggers of autoimmunity in LN. The overabundance of galectin-3-binding protein (G3BP) along with immunoglobulins and a few other proteins specifically distinguish circulating MPs in patients with systemic lupus erythematosus (SLE), and this is most pronounced in patients with active LN. G3BP co-localizes with deposited ICs in renal biopsies from LN patients supporting a significant presence of MPs in the IC deposits. G3BP binds strongly to glomerular basement membrane proteins and integrins. Accordingly, MP surface proteins, especially G3BP, may be essential for the deposition of ICs in kidneys and thus for the ensuing formation of MP-derived electron dense structures in the GBM, and immune activation in LN. This review focuses on the notion of targeting surface molecules on MPs as an entirely novel treatment strategy in LN. By targeting MPs, a double hit may be achieved by attenuating both the autoantigenic fueling of immune complexes and the triggering of the adaptive immune system. Thereby, early pathogenic events may be blocked in contrast to current treatment strategies that primarily target and modulate later events in the cellular and humoral immune response.

  12. Microparticles in the blood of patients with systemic lupus erythematosus (SLE): phenotypic characterization and clinical associations

    Science.gov (United States)

    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

  13. Microparticles Novel Mechanisms of Intracellular Communication: Implication in Health and Disease

    Directory of Open Access Journals (Sweden)

    Anna Meiliana

    2011-04-01

    Full Text Available BACKGROUND: The prevailing view that eukaryotic cells are restrained from intercellular exchange of genetic information has been challenged by recent reports on nanotubes, exosomes, apoptotic bodies, and nucleic acid—binding peptides that provide novel pathways for cell—cell communication, with implications in health and disease. CONTENT: Microparticles (MPs are a heterogeneous population of small plasma membrane structures that serve as important signaling structures between cells. MPs are composed of a phospholipid bilayer that exposes transmembrane proteins and receptors and encloses cytosolic components such as enzymes, transcription factors, and mRNA derived from their parent cells. Growing evidence suggests that MPs regulate inflammation, stimulate coagulation, affect vascular functions and apoptosis, and can also play a role in cell proliferation or differentiation. MPs circulate in the bloodstream, can be detected in the peripheral blood, and may originate from different vascular cell types (eg, platelets, monocytes, endothelial cells, red blood cells, and granulocytes. SUMMARY: Cells of various types release small membrane vesicles called MP on their activation, as well as during the process of apoptosis. The properties and roles of MP generated in different contexts are diverse and are determined by their parent cell and the pathway of their generation, which affects their content. MP are involved in multiple cellular functions, including immunomodulation, inflammation, coagulation, and intercellular communication. MPs are able to deliver molecular signals in the form of lipids, proteins, nucleic acids, or functional trans-membrane proteins from the parent cell to distantly located targets. From a clinical point of view, MP may serve as biomarkers for disease status and may be found useful for developing novel therapeutic strategies. KEYWORDS: microparticles, microvesicle, membrane remodeling, intercellular communication.

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

    Science.gov (United States)

    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 (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. Non-paraxial beam to push and pull microparticles

    DEFF Research Database (Denmark)

    Novitsky, Andrey; Qiu, C.-W.

    2011-01-01

    We discuss a feasibility of the pulling (backward) force acting on a spherical microparticle in a non-paraxial Bessel beam. The effect can be explained by the strong interaction of particle's multipoles or by the conservation of momentum in the system “photons-particle.” It is remarkable that the...

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

    Science.gov (United States)

    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 (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

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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

  19. Magnetic microparticles for harvesting Dunaliella tertiolecta microalgae

    Science.gov (United States)

    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

  20. Charge contribution to patch-charged microparticle adhesion

    Science.gov (United States)

    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.

  1. IGF-1 release kinetics from chitosan microparticles fabricated using environmentally benign conditions

    Energy Technology Data Exchange (ETDEWEB)

    Mantripragada, Venkata P. [Biomedical Engineering Program, The University of Toledo, Toledo, OH 43614-5807 (United States); Jayasuriya, Ambalangodage C., E-mail: a.jayasuriya@utoledo.edu [Biomedical Engineering Program, The University of Toledo, Toledo, OH 43614-5807 (United States); Department of Orthopaedic Surgery, The University of Toledo, Toledo, OH 43614-5807 (United States)

    2014-09-01

    The main objective of this study is to maximize growth factor encapsulation efficiency into microparticles. The novelty of this study is to maximize the encapsulated growth factors into microparticles by minimizing the use of organic solvents and using relatively low temperatures. The microparticles were fabricated using chitosan biopolymer as a base polymer and cross-linked with tripolyphosphate (TPP). Insulin like-growth factor-1 (IGF-1) was encapsulated into microparticles to study release kinetics and bioactivity. In order to authenticate the harms of using organic solvents like hexane and acetone during microparticle preparation, IGF-1 encapsulated microparticles prepared by the emulsification and coacervation methods were compared. The microparticles fabricated by emulsification method have shown a significant decrease (p < 0.05) in IGF-1 encapsulation efficiency, and cumulative release during the two-week period. The biocompatibility of chitosan microparticles and the bioactivity of the released IGF-1 were determined in vitro by live/dead viability assay. The mineralization data observed with von Kossa assay, was supported by mRNA expression levels of osterix and runx2, which are transcription factors necessary for osteoblasts differentiation. Real time RT-PCR data showed an increased expression of runx2 and a decreased expression of osterix over time, indicating differentiating osteoblasts. Chitosan microparticles prepared in optimum environmental conditions are a promising controlled delivery system for cells to attach, proliferate, differentiate and mineralize, thereby acting as a suitable bone repairing material. - Highlights: • Coacervation chitosan microparticles were biocompatible and biodegradable. • IGF-1 encapsulation efficiency increased with coacervation chitosan microparticles. • Coacervation chitosan microparticles support osteoblast attachment and differentiation. • Coacervation chitosan microparticles support osteoblast mineralization.

  2. IGF-1 release kinetics from chitosan microparticles fabricated using environmentally benign conditions

    International Nuclear Information System (INIS)

    The main objective of this study is to maximize growth factor encapsulation efficiency into microparticles. The novelty of this study is to maximize the encapsulated growth factors into microparticles by minimizing the use of organic solvents and using relatively low temperatures. The microparticles were fabricated using chitosan biopolymer as a base polymer and cross-linked with tripolyphosphate (TPP). Insulin like-growth factor-1 (IGF-1) was encapsulated into microparticles to study release kinetics and bioactivity. In order to authenticate the harms of using organic solvents like hexane and acetone during microparticle preparation, IGF-1 encapsulated microparticles prepared by the emulsification and coacervation methods were compared. The microparticles fabricated by emulsification method have shown a significant decrease (p < 0.05) in IGF-1 encapsulation efficiency, and cumulative release during the two-week period. The biocompatibility of chitosan microparticles and the bioactivity of the released IGF-1 were determined in vitro by live/dead viability assay. The mineralization data observed with von Kossa assay, was supported by mRNA expression levels of osterix and runx2, which are transcription factors necessary for osteoblasts differentiation. Real time RT-PCR data showed an increased expression of runx2 and a decreased expression of osterix over time, indicating differentiating osteoblasts. Chitosan microparticles prepared in optimum environmental conditions are a promising controlled delivery system for cells to attach, proliferate, differentiate and mineralize, thereby acting as a suitable bone repairing material. - Highlights: • Coacervation chitosan microparticles were biocompatible and biodegradable. • IGF-1 encapsulation efficiency increased with coacervation chitosan microparticles. • Coacervation chitosan microparticles support osteoblast attachment and differentiation. • Coacervation chitosan microparticles support osteoblast mineralization

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

    Science.gov (United States)

    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.

  4. Effects of simvastatin/ezetimibe on microparticles, endothelial progenitor cells and platelet aggregation in subjects with coronary heart disease under antiplatelet therapy

    Energy Technology Data Exchange (ETDEWEB)

    Camargo, L.M.; França, C.N.; Izar, M.C.; Bianco, H.T.; Lins, L.S.; Barbosa, S.P.; Pinheiro, L.F.; Fonseca, F.A.H. [Universidade Federal de São Paulo, Escola Paulista de Medicina, Departamento de Medicina, São Paulo, SP, Brasil, Departamento de Medicina, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, SP (Brazil)

    2014-04-15

    It is not known whether the addition of ezetimibe to statins adds cardiovascular protection beyond the expected changes in lipid levels. Subjects with coronary heart disease were treated with four consecutive 1-week courses of therapy (T) and evaluations. The courses were: T1, 100 mg aspirin alone; T2, 100 mg aspirin and 40 mg simvastatin/10 mg ezetimibe; T3, 40 mg simvastatin/10 mg ezetimibe, and 75 mg clopidogrel (300 mg initial loading dose); T4, 75 mg clopidogrel alone. Platelet aggregation was examined in whole blood. Endothelial microparticles (CD51), platelet microparticles (CD42/CD31), and endothelial progenitor cells (CD34/CD133; CDKDR/CD133, or CD34/KDR) were quantified by flow cytometry. Endothelial function was examined by flow-mediated dilation. Comparisons between therapies revealed differences in lipids (T2 and T3T1 and T4, P=0.001). Decreased platelet aggregation was observed after aspirin (arachidonic acid, T1circulating endothelial and platelet microparticles, or endothelial progenitor cells. Cardiovascular protection following therapy with simvastatin/ezetimibe seems restricted to lipid changes and improvement of endothelial function not affecting the release of microparticles, mobilization of endothelial progenitor cells or decreased platelet aggregation.

  5. Synthesis and morphology of triangular pyramid-shaped puerarin microparticle with nanostructure

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    A type of triangular pyramid-shaped microparticles of puerarin was synthesized by using oil-in-oil microemulsion approach which is simple and economical under the action of copper substrate.The pyramid-shaped microparticles would be made up of deposit of nanospheres or nanorods and have two significant characters.One is its complex surface morphology like coral reef.The other is a lot of nanopores in existence in the microparticle body.Two possible formation routes were speculated.

  6. Mechanical forces stimulate endothelial microparticle generation via caspase-dependent apoptosis-independent mechanism

    OpenAIRE

    Vion, Anne Clémence; Birukova, Anna A.; Boulanger, Chantal M; Birukov, Konstantin G.

    2013-01-01

    Microparticle release by vascular endothelium has been implicated in various cardiovascular pathologies. Ventilator-induced lung injury (VILI) is a life-threatening complication of mechanical ventilation at high tidal volumes associated with excessive mechanical stretch of pulmonary vascular endothelial cells. However, a role of VILI-relevant levels of cyclic stretch in microparticle generation by vascular endothelium remains unknown. We report microparticle formation by human pulmonary endot...

  7. Growth of a bonelike apatite on chitosan microparticles after a calcium silicate treatment

    OpenAIRE

    Leonor, I. B.; Baran, E. T.; Kawashita, M.; Reis, R. L.; T Kokubo; Nakamura, T

    2008-01-01

    Bioactive chitosan microparticles can be prepared successfully by treating them with a calcium silicate solution and then subsequently soaking them in simulated body fluid (SBF). Such a combination enables the development of bioactive microparticles that can be used for several applications in the medical field, including injectable biomaterial systems and tissue engineering carrier systems. Chitosan microparticles, 0.6 lm in average size, were soaked either for 12 h in fresh calcium...

  8. Effect of Y(OH)_3 microparticles on the electrochemical performance of alkaline zinc electrodes

    Institute of Scientific and Technical Information of China (English)

    张辉; 朱立群; 李卫平; 刘慧丛

    2009-01-01

    This work focused on the zinc powder coated with Y(OH)3 microparticles by means of ultrasonic immersion for performance improvement of zinc electrodes in alkaline battery systems.Scanning electron microscopy and other characterization techniques were applied to examine the influence of the ultrasonic power on the sonochemical growth of Y(OH)3 microparticles in direct contact with zinc powder.Electrochemical properties of zinc electrodes containing Y(OH)3 microparticles were discussed through the measurement...

  9. Using information theory to assess the communicative capacity of circulating microRNA.

    Science.gov (United States)

    Finn, Nnenna A; Searles, Charles D

    2013-10-11

    The discovery of extracellular microRNAs (miRNAs) and their transport modalities (i.e., microparticles, exosomes, proteins and lipoproteins) has sparked theories regarding their role in intercellular communication. Here, we assessed the information transfer capacity of different miRNA transport modalities in human serum by utilizing basic principles of information theory. Zipf Statistics were calculated for each of the miRNA transport modalities identified in human serum. Our analyses revealed that miRNA-mediated information transfer is redundant, as evidenced by negative Zipf's Statistics with magnitudes greater than one. In healthy subjects, the potential communicative capacity of miRNA in complex with circulating proteins was significantly lower than that of miRNA encapsulated in circulating microparticles and exosomes. Moreover, the presence of coronary heart disease significantly lowered the communicative capacity of all circulating miRNA transport modalities. To assess the internal organization of circulating miRNA signals, Shannon's zero- and first-order entropies were calculated. Microparticles (MPs) exhibited the lowest Shannon entropic slope, indicating a relatively high capacity for information transfer. Furthermore, compared to the other miRNA transport modalities, MPs appeared to be the most efficient at transferring miRNA to cultured endothelial cells. Taken together, these findings suggest that although all transport modalities have the capacity for miRNA-based information transfer, MPs may be the simplest and most robust way to achieve miRNA-based signal transduction in sera. This study presents a novel method for analyzing the quantitative capacity of miRNA-mediated information transfer while providing insight into the communicative characteristics of distinct circulating miRNA transport modalities.

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

    Science.gov (United States)

    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.

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

    International Nuclear Information System (INIS)

    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

  12. Detection of environmental radioactive microparticles bearing fissile material

    Energy Technology Data Exchange (ETDEWEB)

    Tamborini, G.; Dequincey, O.; Betti, M. [European Commission, Joint Research Centre, Institute of Transuranium Elements, Karlsruhe (Germany)

    2004-07-01

    Dispersion of actinides and/or fission products in the environment is mainly due to radioactive micro-particles. The determination of the isotopic composition of the major constituents and fissile material in environmental micro-particles is a fundamental fingerprint for the detection of their source term. In order to facilitate the localisation of interesting particles on samples with low density of actinide containing particle and their successive isotopic composition analysis, complementary techniques based on the fission track method and thermal ionisation mass spectrometry (FT-TIMS) are being developed. The main purpose is to use the solid state nuclear track detection (SSNTD) method for the localisation of interesting particles as well as a first estimation of their activity and content of fissile material. In the present work a procedure of rapid recognition of {sup 235}U-enriched particles using this technique is presented as a first step of an analytical procedure for environmental particle survey. (orig.)

  13. Foam injection molding of elastomers with iron microparticles

    Science.gov (United States)

    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.

  14. Multiphase ferrofluid flows for micro-particle sorting

    Science.gov (United States)

    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.

  15. Selective Cell Targeting with Light-Absorbing Microparticles and Nanoparticles

    OpenAIRE

    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 ...

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

    Science.gov (United States)

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

    OpenAIRE

    Shahani, Komal; Panyam, Jayanth

    2011-01-01

    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 peri...

  18. Fabrication of anisotropic microparticles by laser ablation and laser heating

    Energy Technology Data Exchange (ETDEWEB)

    Fukuda, Kozue; Higuchi, Takeshi; Aita, Tadahiro, E-mail: aita@yz.yamagata-u.ac.jp

    2015-02-01

    Laser ablation and laser heating were used as micro-cutting and micro-bonding tools for fabrication of anisotropic microparticles. By using the techniques, two kinds of anisotropic microparticles to which a polymer film or magnetic particles was attached on their one hemisphere were fabricated from transparent spherical acrylic polymer particles of about 10 μm. In the fabrication of the anisotropic particles to which a polymer film attached, a mono-particle layer of the acrylic polymer particles formed on water surface was transferred on to a target plate coated with a polymer film and the plate was heated so that the particles strongly adhered to the polymer film. The plate was irradiated by 1064 nm or 532 nm pulse light from a Q-switched YAG laser to cause the ablation of the target. The ablation blew off the polymer film together with the acrylic polymer particles from the target plate, which gave the anisotropic particles. Anisotropic particles to which magnetic particles attached on their one hemisphere were fabricated by laser heating. A magnetic particle layer formed on water surface was transferred onto a quartz plate and then the monoparticle layer of the acrylic polymer particles was transferred onto the magnetic particle layer. The magnetic particles were heated by irradiation of 808 nm light from a CW diode laser, which caused the adhesion of the magnetic particles to the polymer particles. Rotation of the obtained magnetically anisotropic particles under rotating magnetic field was demonstrated. - Highlights: • Laser ablation and laser heating were used for fabrication of anisotropic particles. • Anisotropic microparticles having a polymer film or magnetic particles on their one hemisphere were fabricated. • The magnetically anisotropic microparticles rotated under a rotating magnetic field.

  19. Incorporation of iodine in polymeric microparticles and emulsions

    Science.gov (United States)

    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.

  20. Endothelial microparticles and the diagnosis of the vasculitides.

    OpenAIRE

    Brogan, P A; Dillon, M. J.

    2004-01-01

    Recently there has been considerable interest in a novel surrogate marker of endothelial injury, endothelial microparticles (EMP), in a number of diseases characterised by endothelial injury. This review examines the data relating to EMP in human disease states, and examines the potential for EMP to provide a window onto the activated endothelium in primary systemic vasculitides. The utility of EMP for the diagnosis and monitoring of active vasculitis is discussed.

  1. PREPARATION AND CHARACTERIZATION OF SPRAY DRIED MICROPARTICLE OF CARBAMAZEPINE

    OpenAIRE

    Dixit Mudit; Kulkarni Parthasarathi Keshavarao; Johri Akash; Kini G Ashwini

    2011-01-01

    Carbamazepine, an antiepileptic 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 Carbamazepine. Microparticle containing Carbamazepine was produced by spray drying using Isopropyl alcohol and water in the ratio of 40:60 (v/v) as solvent system to enhance dissolution rate. The prepared formulations were evaluated for in vitro dissolution and solubility. The prepared drug particles ...

  2. Formulation and evaluation of verapamil hydrochloride loaded solid lipid microparticles.

    Science.gov (United States)

    Pilaniya, U; Pilaniya, K; Chandrawanshi, H K; Gupta, N; Rajput, M S

    2011-01-01

    The present study aimed to produce verapamil hydrochloride-loaded solid lipid microparticles (SLM) by the w/o/w emulsion solvent evaporation technique, using diethyl ether as solvent phase, glyceryl monostearate as biodegradable polymer and Span 60 as surfactant. SLM of spherical shape were prepared by simple dilution of the emulsion with water. To increase the lipid load the process was conducted at 50 degrees C, and in order to reach sub-micron size, a high-shear homogenizer was used. The encapsulation efficiency of prepared SLM reached 74.29 +/- 0.76%. Particle size (98.55 +/- 1.42 microm), surface morphology (spherical) and drug loading efficiency (18.57 +/- 1.25% w/w) were investigated. And optimization of drug polymer ratio (3:1), nature and concentration of emulsion stabilizer in the external aqueous (0.1%), phase viscosity of external aqueous phase (0.5%), volume of external aqueous phase and stirring rate (1000 rpm) were detected. Analysis of microsphere content after processing showed that verapamil did not undergo any chemical modification within the micro-particles. The in-vitro release of verapamil from the microparticles was very low and an initial burst effect of 17% of the dose was observed. The slow release may help to avoid a high frequency of administration. The prepared solid lipid microparticles appear to have interesting perspectives as delivery systems for the oral administration of verapamil hydrochloride with improved half-life, improved bioavailability, and minimized local and systemic gastrointestinal disturbances of the drug. PMID:21391431

  3. Pneumatic capillary gun for ballistic delivery of microparticles

    CERN Document Server

    Rinberg, D; Groisman, A; Rinberg, Dmitry; Simonnet, Claire; Groisman, Alex

    2005-01-01

    A pneumatic gun for ballistic delivery of microparticles to soft targets is proposed and demonstrated. The particles are accelerated by a high speed flow of Helium in a capillary tube. Vacuum suction applied to a concentric, larger diameter tube is used to completely divert the flow of Helium from the gun nozzle and prevent it from hitting the target. Depths of penetration of micron-sized gold particles into agarose gels and their speeds of ejection from the gun nozzle are measured.

  4. Effect of Irradiation on Microparticles in Red Blood Cell Concentrates

    OpenAIRE

    Cho, Chi Hyun; Yun, Seung Gyu; Koh, Young Eun; Lim, Chae Seung

    2016-01-01

    Changes in microparticles (MP) from red blood cell (RBC) concentrates in the context of irradiation have not been investigated. The aim of this study was to evaluate how irradiation affects the number of MPs within transfusion components. Twenty RBC concentrates, within 14 days after donation, were exposed to gamma rays (dose rate: 25 cGy) from a cesium-137 irradiator. Flow cytometry was used to determine the numbers of MPs derived from RBC concentrates before and 24 hr after irradiation. The...

  5. Floating microparticles based on low density foam powder.

    Science.gov (United States)

    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.

  6. Moldless PEGDA-Based Optoelectrofluidic Platform for Microparticle Selection

    Directory of Open Access Journals (Sweden)

    Shih-Mo Yang

    2011-01-01

    Full Text Available This paper reports on an optoelectrofluidic platform which consists of the organic photoconductive material, titanium oxide phthalocyanine (TiOPc, and the photocrosslinkable polymer, poly (ethylene glycol diacrylate (PEGDA. TiOPc simplifies the fabrication process of the optoelectronic chip due to requiring only a single spin-coating step. PEGDA is applied to embed the moldless PEGDA-based microchannel between the top ITO glass and the bottom TiOPc substrate. A real-time control interface via a touch panel screen is utilized to select the target 15 μm polystyrene particles. When the microparticles flow to an illuminating light bar, which is oblique to the microfluidic flow path, the lateral driving force diverts the microparticles. Two light patterns, the switching oblique light bar and the optoelectronic ladder phenomenon, are designed to demonstrate the features. This work integrating the new material design, TiOPc and PEGDA, and the ability of mobile microparticle manipulation demonstrates the potential of optoelectronic approach.

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

    Science.gov (United States)

    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

  8. Functionalized diatom silica microparticles for removal of mercury ions

    Directory of Open Access Journals (Sweden)

    Yang Yu, Jonas Addai-Mensah and Dusan Losic

    2012-01-01

    Full Text Available Diatom silica microparticles were chemically modified with self-assembled monolayers of 3-mercaptopropyl-trimethoxysilane (MPTMS, 3-aminopropyl-trimethoxysilane (APTES and n-(2-aminoethyl-3-aminopropyl-trimethoxysilane (AEAPTMS, and their application for the adsorption of mercury ions (Hg(II is demonstrated. Fourier transform infrared spectroscopy and x-ray photoelectron spectroscopy analyses revealed that the functional groups (–SH or –NH2 were successfully grafted onto the diatom silica surface. The kinetics and efficiency of Hg(II adsorption were markedly improved by the chemical functionalization of diatom microparticles. The relationship among the type of functional groups, pH and adsorption efficiency of mercury ions was established. The Hg(II adsorption reached equilibrium within 60 min with maximum adsorption capacities of 185.2, 131.7 and 169.5 mg g-1 for particles functionalized with MPTMS, APTES and AEAPTMS, respectively. The adsorption behavior followed a pseudo-second-order reaction model and Langmuirian isotherm. These results show that mercapto- or amino-functionalized diatom microparticles are promising natural, cost-effective and environmentally benign adsorbents suitable for the removal of mercury ions from aqueous solutions.

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

    Science.gov (United States)

    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

  10. The effects of smoking on levels of endothelial progenitor cells and microparticles in the blood of healthy volunteers.

    Directory of Open Access Journals (Sweden)

    Fariborz Mobarrez

    Full Text Available BACKGROUND: Cigarette smoking, both active and passive, is one of the leading causes of morbidity and mortality in cardiovascular disease. To assess the impact of brief smoking on the vasculature, we determined levels of circulating endothelial progenitor cells (EPCs and circulating microparticles (MPs following the smoking of one cigarette by young, healthy intermittent smokers. MATERIALS AND METHODS: 12 healthy volunteers were randomized to either smoking or not smoking in a crossover fashion. Blood sampling was performed at baseline, 1, 4 and 24 hours following smoking/not smoking. The numbers of EPCs and MPs were determined by flow cytometry. MPs were measured from platelets, leukocytes and endothelial cells. Moreover, MPs were also labelled with anti-HMGB1 and SYTO 13 to assess the content of nuclear molecules. RESULTS: Active smoking of one cigarette caused an immediate and significant increase in the numbers of circulating EPCs and MPs of platelet-, endothelial- and leukocyte origin. Levels of MPs containing nuclear molecules were increased, of which the majority were positive for CD41 and CD45 (platelet- and leukocyte origin. CD144 (VE-cadherin or HMGB1 release did not significantly change during active smoking. CONCLUSION: Brief active smoking of one cigarette generated an acute release of EPC and MPs, of which the latter contained nuclear matter. Together, these results demonstrate acute effects of cigarette smoke on endothelial, platelet and leukocyte function as well as injury to the vascular wall.

  11. Nano/microparticles and ultrasound contrast agents

    Institute of Scientific and Technical Information of China (English)

    Shu-Guang; Zheng; Hui-Xiong; Xu; Hang-Rong; Chen

    2013-01-01

    Microbubbles have been used for many years now in clinical practice as contrast agents in ultrasound imaging.Recently,their therapeutic applications have also attracted more attention.However,the short circulation time(minutes)and relatively large size(two to ten micrometers)of currently used commercial microbubbles do not allow effective extravasation into tumor tissue,preventing efficient tumor targeting.Fortunately,more multifunctional and theranostic nanoparticles with some special advantages over the traditional microbubbles have been widely investigated and explored for biomedical applications.The way to synthesize an ideal ultrasound contrast agent based on nanoparticles in order to achieve an expected effect on contrast imaging is a key technique.Currently a number of nanomaterials,including liposomes,polymers,micelles,dendrimers,emulsions,quantum dots,solid nanoparticles etc.,have already been applied to pre or clinical trials.Multifunctional and theranostic nanoparticles with some special advantages,such as the tumor-targeted(passive or active),multi-mode contrast agents(magnetic resonance imaging,ultrasonography or fluorescence),carrier or enhancer of drug delivery,and combined chemo or thermal therapy etc.,are rapidly gaining popularity and have shown a promising application in the field of cancer treatment.In this mini review,the trends and the advances of multifunctional and theranostic nanoparticles are briefly discussed.

  12. Microparticles as new markers of cardiovascular risk in diabetes and beyond.

    Science.gov (United States)

    Santilli, Francesca; Marchisio, Marco; Lanuti, Paola; Boccatonda, Andrea; Miscia, Sebastiano; Davì, Giovanni

    2016-08-01

    The term microparticle (MP) identifies a heterogeneous population of vesicles playing a relevant role in the pathogenesis of vascular diseases, cancer and metabolic diseases such as diabetes mellitus. MPs are released by virtually all cell types by shedding during cell growth, proliferation, activation, apoptosis or senescence processes. MPs, in particular platelet- and endothelial-derived MPs (PMPs and EMPs), are increased in a wide range of thrombotic disorders, with an interesting relationship between their levels and disease pathophysiology, activity or progression. EMP plasma levels have been associated with several cardiovascular diseases and risk factors. PMPs are also shown to be involved in the progressive formation of atherosclerotic plaque and development of arterial thrombosis, especially in diabetic patients. Indeed, diabetes is characterised by an increased procoagulant state and by a hyperreactive platelet phenotype, with enhanced adhesion, aggregation, and activation. Elevated MP levels, such as TF+ MPs, have been shown to be one of the procoagulant determinants in patients with type 2 diabetes mellitus. Atherosclerotic plaque constitutes an opulent source of sequestered MPs, called "plaque" MPs. Otherwise, circulating MPs represent a TF reservoir, named "blood-borne" TF, challenging the dogma that TF is a constitutive protein expressed in minute amounts. "Blood-borne" TF is mainly harboured by PMPs, and it can be trapped within the developing thrombus. MP detection and enumeration by polychromatic flow cytometry (PFC) have opened interesting perspectives in clinical settings, particularly for the evaluation of MP numbers and phenotypes as independent marker of cardiovascular risk, disease and outcome in diabetic patients. PMID:27173919

  13. Indolic Uremic Solutes Enhance Procoagulant Activity of Red Blood Cells through Phosphatidylserine Exposure and Microparticle Release

    Directory of Open Access Journals (Sweden)

    Chunyan Gao

    2015-10-01

    Full Text Available Increased accumulation of indolic uremic solutes in the blood of uremic patients contributes to the risk of thrombotic events. Red blood cells (RBCs, the most abundant blood cells in circulation, may be a privileged target of these solutes. However, the effect of uremic solutes indoxyl sulfate (IS and indole-3-acetic acid (IAA on procoagulant activity (PCA of erythrocyte is unclear. Here, RBCs from healthy adults were treated with IS and IAA (mean and maximal concentrations reported in uremic patients. Phosphatidylserine (PS exposure of RBCs and their microparticles (MPs release were labeled with Alexa Fluor 488-lactadherin and detected by flow cytometer. Cytosolic Ca2+ ([Ca2+] with Fluo 3/AM was analyzed by flow cytometer. PCA was assessed by clotting time and purified coagulation complex assays. We found that PS exposure, MPs generation, and consequent PCA of RBCs at mean concentrations of IS and IAA enhanced and peaked in maximal uremic concentrations. Moreover, 128 nM lactadherin, a PS inhibitor, inhibited over 90% PCA of RBCs and RMPs. Eryptosis or damage, by indolic uremic solutes was due to, at least partially, the increase of cytosolic [Ca2+]. Our results suggest that RBC eryptosis in uremic solutes IS and IAA plays an important role in thrombus formation through releasing RMPs and exposing PS. Lactadherin acts as an efficient anticoagulant in this process.

  14. Indolic uremic solutes enhance procoagulant activity of red blood cells through phosphatidylserine exposure and microparticle release.

    Science.gov (United States)

    Gao, Chunyan; Ji, Shuting; Dong, Weijun; Qi, Yushan; Song, Wen; Cui, Debin; Shi, Jialan

    2015-11-01

    Increased accumulation of indolic uremic solutes in the blood of uremic patients contributes to the risk of thrombotic events. Red blood cells (RBCs), the most abundant blood cells in circulation, may be a privileged target of these solutes. However, the effect of uremic solutes indoxyl sulfate (IS) and indole-3-acetic acid (IAA) on procoagulant activity (PCA) of erythrocyte is unclear. Here, RBCs from healthy adults were treated with IS and IAA (mean and maximal concentrations reported in uremic patients). Phosphatidylserine (PS) exposure of RBCs and their microparticles (MPs) release were labeled with Alexa Fluor 488-lactadherin and detected by flow cytometer. Cytosolic Ca(2+) ([Ca(2+)]) with Fluo 3/AM was analyzed by flow cytometer. PCA was assessed by clotting time and purified coagulation complex assays. We found that PS exposure, MPs generation, and consequent PCA of RBCs at mean concentrations of IS and IAA enhanced and peaked in maximal uremic concentrations. Moreover, 128 nM lactadherin, a PS inhibitor, inhibited over 90% PCA of RBCs and RMPs. Eryptosis or damage, by indolic uremic solutes was due to, at least partially, the increase of cytosolic [Ca(2+)]. Our results suggest that RBC eryptosis in uremic solutes IS and IAA plays an important role in thrombus formation through releasing RMPs and exposing PS. Lactadherin acts as an efficient anticoagulant in this process. PMID:26516916

  15. Principle and Method of Preparation of Explosive Micro-particles Through the Supercritical Anti-solvent Process

    Institute of Scientific and Technical Information of China (English)

    JIN Liang-an; LIU Xue-wu; LI Zhi-yi; WANG Xiao-tong; YIN Xing-bo

    2005-01-01

    In explosive research area, one of important trends is to study on the preparation technology of explosive microparticles. A new principle and method based on supercritical anti-solvent (SAS) process is put forward and discussed for the preparation of explosive micro-particles. The satisfactory micro-particles of explosives can be obtained easily by its particular mechanism of creating micro-particles, and operating conditions at normal temperature. This method is good for further study and development.

  16. Microparticle-Induced Coagulation Relates to Coronary Artery Atherosclerosis in Severe Aortic Valve Stenosis.

    Directory of Open Access Journals (Sweden)

    Patrick Horn

    Full Text Available Circulating microparticles (MPs derived from endothelial cells and blood cells bear procoagulant activity and promote thrombin generation. Thrombin exerts proinflammatory effects mediating the progression of atherosclerosis. Aortic valve stenosis may represent an atherosclerosis-like process involving both the aortic valve and the vascular system. The aim of this study was to investigate whether MP-induced thrombin generation is related to coronary atherosclerosis and aortic valve calcification.In a cross-sectional study of 55 patients with severe aortic valve stenosis, we assessed the coronary calcification score (CAC as indicator of total coronary atherosclerosis burden, and aortic valve calcification (AVC by computed tomography. Thrombin-antithrombin complex (TATc levels were measured as a marker for thrombin formation. Circulating MPs were characterized by flow cytometry according to the expression of established surface antigens and by measuring MP-induced thrombin generation.Patients with CAC score below the median were classified as patients with low CAC, patients with CAC Score above the median as high CAC. In patients with high CAC compared to patients with low CAC we detected higher levels of TATc, platelet-derived MPs (PMPs, endothelial-derived MPs (EMPs and MP-induced thrombin generation. Increased level of PMPs and MP-induced thrombin generation were independent predictors for the severity of CAC. In contrast, AVC Score did not differ between patients with high and low CAC and did neither correlate with MPs levels nor with MP-induced thrombin generation.In patients with severe aortic valve stenosis MP-induced thrombin generation was independently associated with the severity of CAC but not AVC indicating different pathomechanisms involved in coronary artery and aortic valve calcification.

  17. Formulation of porous poly(lactic-co-glycolic acid) microparticles by electrospray deposition method for controlled drug release

    Energy Technology Data Exchange (ETDEWEB)

    Hao, Shilei; Wang, Yazhou; Wang, Bochu, E-mail: wangbc2000@126.com; 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. - Highlights: • The porous PLGA microparticles were successfully prepared by the electrospray deposition method at one step. • The porous microparticles had high loading capacity and low density. • The microparticle showed a sustained release in the simulated gastric liquid. • The microparticles showed a slight cytotoxicity in vitro.

  18. Facile and High-Throughput Synthesis of Functional Microparticles with Quick Response Codes.

    Science.gov (United States)

    Ramirez, Lisa Marie S; He, Muhan; Mailloux, Shay; George, Justin; Wang, Jun

    2016-06-01

    Encoded microparticles are high demand in multiplexed assays and labeling. However, the current methods for the synthesis and coding of microparticles either lack robustness and reliability, or possess limited coding capacity. Here, a massive coding of dissociated elements (MiCODE) technology based on innovation of a chemically reactive off-stoichimetry thiol-allyl photocurable polymer and standard lithography to produce a large number of quick response (QR) code microparticles is introduced. The coding process is performed by photobleaching the QR code patterns on microparticles when fluorophores are incorporated into the prepolymer formulation. The fabricated encoded microparticles can be released from a substrate without changing their features. Excess thiol functionality on the microparticle surface allows for grafting of amine groups and further DNA probes. A multiplexed assay is demonstrated using the DNA-grafted QR code microparticles. The MiCODE technology is further characterized by showing the incorporation of BODIPY-maleimide (BDP-M) and Nile Red fluorophores for coding and the use of microcontact printing for immobilizing DNA probes on microparticle surfaces. This versatile technology leverages mature lithography facilities for fabrication and thus is amenable to scale-up in the future, with potential applications in bioassays and in labeling consumer products. PMID:27151936

  19. Nicotine-magnesium aluminum silicate microparticle surface modified with chitosan for mucosal delivery

    DEFF Research Database (Denmark)

    Kanjanakawinkul, Watchara; Rades, Thomas; Puttipipatkhachorn, Satit;

    2013-01-01

    Magnesium aluminum silicate (MAS), a negatively charged clay, and nicotine (NCT), a basic drug, can interact electrostatically to form microparticles. Chitosan (CS) was used for the surface modification of the microparticles, and a lyophilization method was used to preserve the original particle...

  20. First-principle simulation of the acoustic radiation force on microparticles in ultrasonic standing waves

    DEFF Research Database (Denmark)

    Jensen, Mads Jakob Herring; Bruus, Henrik

    2013-01-01

    The recent development in the field of microparticle acoutophoresis in microsystems has led to an increased need for more accurate theoretical predections for the acoustic radiation force on a single microparticle in an ultrasonic standing wave. Increasingly detailed analytical solutions of this ...

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

    Science.gov (United States)

    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

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

    Science.gov (United States)

    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

  3. Eudragit® microparticles for the release of budesonide: A comparative study

    Directory of Open Access Journals (Sweden)

    Rita Cortesi

    2012-01-01

    Full Text Available This study compares the behaviour of budesonide-containing microparticles made of Eudragit® RS or Eudragit® RS/Eudragit® RL 70:30 (w/w prepared either by solvent evaporation or spray-drying technique. The loading efficiency of budesonide within microparticles was about 72% for microparticles prepared by solvent evaporation and around 78% for spray-dried microparticles. Thermal analyses were assessed to collect information about the structural stability of budesonide within the polymeric microspheres. The in vitro release was performed using simulating gastric (fasted state simulated gastric fluid and intestinal (fasted state simulated intestinal fluid fluids as the receiving solutions. After 3 h the drug release from Eudragit® RS/Eudragit® RL microparticles was about 6-fold higher than that obtained in the case of monopolymer microparticles. Using fasted state simulated intestinal fluid the drug was released between 4 and 30% in both types of preparations. Eudragit® RS microparticles showed a better protection of the drug from gastric acidity than those of Eudragit® RS/Eudragit® RL allowing us to propose Eudragit® RS microparticles as a hypothetical system of colon specific controlled delivery.

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

    Science.gov (United States)

    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.

  5. Lipid Level and Its Impact on Syncytiotrophoblast Microparticles Inducing Preeclampsia%脂质及其在合体滋养细胞微粒导致子痫前期过程中的影响

    Institute of Scientific and Technical Information of China (English)

    李柳叶

    2013-01-01

    微粒是细胞受到刺激活化或凋亡后产生的细胞碎片,在循环中微粒作为运载工具承载和转运多种蛋白质、DNA片段和RNA片段,在细胞间信号传递过程起作用.微粒可以促进血栓形成,介导促炎效应,也可能直接导致内皮细胞功能紊乱.体内多种细胞都可以产生微粒.研究发现子痫前期患者体内合体滋养细胞微粒的释放明显多于正常妊娠者.体外研究还发现,微粒样品中脂质水平对脐静脉内皮细胞的增殖及凋亡也有影响.脂质水平越高,则微粒样品抑制脐静脉内皮细胞增殖和促进其凋亡的能力就越强.摄入高脂饮食者循环中微粒总量较正常饮食者高.%Microparticles are cell fragments that derived from cell activation and/or apoptosis.Cycling microparticles can serve as vehicles carrying and transporting varieties of proteins and frangements of DNA or RNA.Microparticles can promote thrombus formation,mediate pro-inflammatory effects and may cause endothelial dysfunction directly.Most kinds of cells in human can produce microparticles.Studies have found a much higher formation of syncytiotrophoblast microparticles in preeclampsia women than normal pregnancies.Studies in vitro also found that the lipid levels in microparticles can impact their abilities of inhibiting proliferation and promoting apotosis in human umbilical vein endothelial cell.The higher lipid levels,the stronger abilities to inhibit proliferation and promote apoptosis.In another study,volunteers intaking high fat diet have higher level of total circulation microparticles than normal diet.

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

    Science.gov (United States)

    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

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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

  9. Accelerating protein release from microparticles for regenerative medicine applications

    International Nuclear Information System (INIS)

    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. Highlights: ► A new delivery system providing controlled release kinetics has been developed. ► Inclusion of hydrophilic PLGA–PEG–PLGA decoupled release kinetics from degradation. ► Using 10% triblock copolymer produced quasi zero order release over four weeks. ► Mixing microparticle formulations provided another route for controlling release. ► This system provides customisable, localised and controlled delivery of growth factors

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

    Directory of Open Access Journals (Sweden)

    Baert K

    2016-05-01

    Full Text Available Kim Baert,1 Bruno G De Geest,2 Henri De Greve,3,4 Eric Cox,1,* Bert Devriendt1,* 1Department of Virology, Parasitology and Immunology, 2Department of Pharmaceutics, Ghent University, Merelbeke, Ghent, Belgium; 3Structural Biology Research Centre, VIB, Brussels, Belgium; 4Structural Biology Brussels, Vrije Universiteit Brussel, Brussels, Belgium *These authors contributed equally to this work Abstract: 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. Keywords: β-glucan microparticles, FedF, antigen delivery vehicle, immunostimulants

  11. Accelerating protein release from microparticles for regenerative medicine applications

    Energy Technology Data Exchange (ETDEWEB)

    White, Lisa J., E-mail: lisa.white@nottingham.ac.uk; Kirby, Giles T.S.; Cox, Helen C.; Qodratnama, Roozbeh; Qutachi, Omar; Rose, Felicity R.A.J.; Shakesheff, Kevin M.

    2013-07-01

    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. Highlights: ► A new delivery system providing controlled release kinetics has been developed. ► Inclusion of hydrophilic PLGA–PEG–PLGA decoupled release kinetics from degradation. ► Using 10% triblock copolymer produced quasi zero order release over four weeks. ► Mixing microparticle formulations provided another route for controlling release. ► This system provides customisable, localised and controlled delivery of growth factors.

  12. Single microparticles mass measurement using an AFM cantilever resonator

    CERN Document Server

    Mauro, Marco; Ferrini, Gianluca; Puglisi, Roberto; Balduzzi, Donatella; Galli, Andrea

    2014-01-01

    In this work is presented a microbalance for single microparticle sensing based on resonating AFM cantilever. The variation of the resonator eigenfrequency is related to the particle mass positioned at the free apex of the cantilever. An all-digital phase locked loop (PLL) control system is developed to detect the variations in cantilever eigenfrequency. Two particle populations of different materials are used in the experimental test, demonstrating a mass sensitivity of 15 Hz/pg in ambient conditions. Thereby it is validated the possibility of developing an inexpensive, portable and sensitive microbalance for point-mass sensing.

  13. Manipulation of microparticles and red blood cells using optoelectronic tweezers

    Indian Academy of Sciences (India)

    R S Verma; R Dasgupta; N Kumar; S Ahlawat; A Uppal; P K Gupta

    2014-02-01

    We report the development of an optoelectronic tweezers set-up which works by lightinduced dielectrophoresis mechanism to manipulate microparticles. We used thermal evaporation technique for coating the organic polymer, titanium oxide phthalocyanine (TiOPc), as a photoconductive layer on ITO-coated glass slide. Compare to the conventional optical tweezers, the technique requires optical power in W range and provides a manipulation area of a few mm2. The set-up was used to manipulate the polystyrene microspheres and red blood cells (RBCs). The RBCs could be attracted or repelled by varying the frequency of the applied AC bias.

  14. Microwave circulator design

    CERN Document Server

    Linkhart, Douglas K

    2014-01-01

    Circulator design has advanced significantly since the first edition of this book was published 25 years ago. The objective of this second edition is to present theory, information, and design procedures that will enable microwave engineers and technicians to design and build circulators successfully. This resource contains a discussion of the various units used in the circulator design computations, as well as covers the theory of operation. This book presents numerous applications, giving microwave engineers new ideas about how to solve problems using circulators. Design examples are provided, which demonstrate how to apply the information to real-world design tasks.

  15. Novel hierarchical microparticles super-assembled from nanoparticles with the induction of casein micelles

    Energy Technology Data Exchange (ETDEWEB)

    Xiong, Xiaopeng, E-mail: xpxiong@xmu.edu.cn; Duan, Jiangjiang; Wang, Yong; Yu, Zhaoju [Xiamen University, Department of Materials Science and Engineering, College of Materials (China)

    2013-08-15

    We have demonstrated a solution-based synthesis of novel waxberry-like hierarchical ZnO microparticles in the presence casein micelles under mild conditions. The microstructures of the sub-micrometer-sized hierarchical microparticles were characterized, and the synthesis conditions were optimized. The formation mechanism of the hierarchical microparticle was analyzed through control experiments. The hierarchical ZnO microparticles are found to be super-assemblies of 30-70 nm ZnO nanoparticles, which are thought to be based on casein micelle induction followed by Ostwald ripening. In the same manner, copper-based hierarchical microparticles with a similar morphology have also been successfully synthesized. By controlling the synthetic time or temperature, solid or hollow microparticles can be fabricated. The narrowly distributed ZnO microparticles have a high specific surface area, exhibiting great potential application in fields such as photocatalytic and energy conversion. Our findings may meanwhile open a new bottom-up strategy in order to construct structurally sophisticated nanomaterials.

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

    Science.gov (United States)

    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

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

    Science.gov (United States)

    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.

  18. Phoretic Force Measurement for Microparticles Under Microgravity Conditions

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

  20. New alginic acid–atenolol microparticles for inhalatory drug targeting

    Energy Technology Data Exchange (ETDEWEB)

    Ceschan, Nazareth Eliana; Bucalá, Verónica [Planta Piloto de Ingeniería Química (PLAPIQUI), CONICET, Universidad Nacional del Sur (UNS), Camino La Carrindanga Km 7, 8000 Bahía Blanca (Argentina); Departamento de Ingeniería Química, UNS, Avenida Alem 1253, 8000 Bahía Blanca (Argentina); Ramírez-Rigo, María Verónica, E-mail: vrrigo@plapiqui.edu.ar [Planta Piloto de Ingeniería Química (PLAPIQUI), CONICET, Universidad Nacional del Sur (UNS), Camino La Carrindanga Km 7, 8000 Bahía Blanca (Argentina); Departamento de Biología, Bioquímica y Farmacia, UNS, San Juan 670, 8000 Bahía Blanca (Argentina)

    2014-08-01

    The inhalatory route allows drug delivery for local or systemic treatments in a noninvasively way. The current tendency of inhalable systems is oriented to dry powder inhalers due to their advantages in terms of stability and efficiency. In this work, microparticles of atenolol (AT, basic antihypertensive drug) and alginic acid (AA, acid biocompatible polyelectrolyte) were obtained by spray drying. Several formulations, varying the relative composition AT/AA and the total solid content of the atomized dispersions, were tested. The powders were characterized by: Fourier Transform Infrared Spectroscopy, Differential Scanning Calorimetry and Powder X-ray Diffraction, while also the following properties were measured: drug load efficiency, flow properties, particles size and density, moisture content, hygroscopicity and morphology. The ionic interaction between AA and AT was demonstrated, then the new chemical entity could improve the drug targeting to the respiratory membrane and increase its time residence due to the mucoadhesive properties of the AA polymeric chains. Powders exhibited high load efficiencies, low moisture contents, adequate mean aerodynamic diameters and high cumulative fraction of respirable particles (lower than 10 μm). - Highlights: • Novel particulate material to target atenolol to the respiratory membrane was developed. • Crumbled microparticles were obtained by spray drying of alginic–atenolol dispersions. • Ionic interaction between alginic acid and atenolol was demonstrated in the product. • Amorphous solids with low moisture content and high load efficiency were produced. • Relationships between the feed formulation and the product characteristics were found.

  1. Fluid-Structure Interactions and Microparticle Transport in Pulmonary Alveoli

    Science.gov (United States)

    Ghadiali, Samir

    2005-11-01

    The transport of micron-size particles in the lung has important implications for both respiratory disorders and drug delivery systems. During breathing, the expansion of pulmonary alveoli produces sub-ambient pressures that draw airflow into the lung. The fate of inhaled microparticles during breathing will depend on both particle properties and the complex transient flow fields generated by alveolar wall motion. In this study, fluid-structure interaction (FSI) models are used to evaluate the effects of breathing rates, particle size, tissue viscoelasticity and surface tension forces on microparticle transport. In addition to fluid and solid dynamic equations, these models solve a particle equation of motion that includes both Brownian diffusion and gravitational terms. Our results indicate that Brownian diffusion is the dominant mechanism of transport for particles smaller than one micron and that the elastic properties of alveolar tissues can significantly affect particle deposition. Particles larger than 0.5 microns also experience significant gravitational sedimentation, while convection forces become increasingly dominant for larger particles and faster breathing rates. These results may be useful in designing improved drug delivery systems and in establishing new threshold levels for exposure to viral agents. Supported by the NSF and Parker B. Francis Foundation.

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

    Science.gov (United States)

    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. Formation of Gold Microparticles by Ablation with Surface Plasmons

    Directory of Open Access Journals (Sweden)

    Pal Molian

    2013-10-01

    Full Text Available The formation of gold microparticles on a silicon substrate through the use of energetic surface plasmons is reported. A laser-assisted plasmonics system was assembled and tested to synthesize gold particles from gold thin film by electrical field enhancement mechanism. A mask containing an array of 200 nm diameter holes with a periodicity of 400 nm was prepared and placed on a silicon substrate. The mask was composed of 60 µm thick porous alumina membrane sputter-coated with 100 nm thin gold film. A Nd:YAG laser with 1064 nm wavelength and 230 µs pulse width (free-running mode was then passed through the mask at an energy fluence of 0.35 J/cm2. The extraordinary transmission of laser light through alumina/gold micro-hole optical antenna created both extended and localized surface plasmons that caused the gold film at the bottom of the mask to fragment into microparticles and deposit on the silicon substrate that is in direct contact with the mask. The surface plasmon method is simpler, quicker, more energy efficient, and environmentally safer than existing physical and chemical methods, as well as being contamination-free, and can be extended to all types of materials that will in turn allow for new possibilities in the formation of structured surfaces.

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

    Science.gov (United States)

    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.

  5. The preservation of living cells with biocompatible microparticles

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

  7. Diagnostics of a multicharged heavy ion beam with the help of microparticle distributed target

    International Nuclear Information System (INIS)

    Experiment with the heavy ion accelerator (U-400 isochronous cyclotron) were made by using a dispersed volume internal target for the ion beam diagnostic development. The target has been prepared in vacuum with microparticles of luminophor or other materials. The dispersal of microparticles dust has been made with the electromechanical microvibrator for a short time interval equal to few seconds. Microparticles have been heated before hand in vacuum to remove residual gas. The investigation results have been shown significant possibilities of the new perturbation diagnostic method. The information about ion coordinates, internal structure, quality of magnetic field compression, ion current magnitude may be presented at a display. 7 refs.; 3 figs

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

    Science.gov (United States)

    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.

  9. Preparation and characteristics of high-amylose corn starch/pectin blend microparticles: A technical note

    OpenAIRE

    Desai, Kashappa Goud H.

    2005-01-01

    The HACS/pectin blend microparticles were prepared by spray-drying technique to obtain effective targeted drug release to the colon. The mean particle size of the micro-particles (plain and blend) that were prepared in the present study was between 5.8 and 7.3 μm. The microparticles were positively charged (ζ potential was in the range of 20.3 to 30.8), and the encapsulation efficiency was between 80.1% and 94.7%. The blending of HACS with pectin improved the encapsulation efficiency and decr...

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

    International Nuclear Information System (INIS)

    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

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

    Science.gov (United States)

    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.

  12. Pullulan: an advantageous natural polysaccharide excipient to formulate tablets of alendronate-loaded microparticles

    Directory of Open Access Journals (Sweden)

    Luana Mota Ferreira

    2015-03-01

    Full Text Available This work reports the preparation of tablets by direct compression of sodium alendronate-loaded microparticles, using pullulan as filler. The tableting properties of pullulan were compared with those of microcrystalline cellulose and lactose. Pullulan tablets showed low variations in average weight, thickness and drug content. Moreover, these tablets exhibited a higher hardness compared to the other excipients. In vitro release studies showed that only pullulan was capable to maintain gastroresistance and release properties of microparticles, due to its ability to protect particles against damage caused by compression force. Thus, pullulan was considered an advantageous excipient to prepare tableted microparticles.

  13. Mountains and Tropical Circulation

    Science.gov (United States)

    Naiman, Z.; Goodman, P. J.; Krasting, J. P.; Malyshev, S.; Russell, J. L.; Stouffer, R. J.

    2015-12-01

    Observed tropical convection exhibits zonal asymmetries that strongly influence spatial precipitation patterns. The drivers of changes to this zonally-asymmetric Walker circulation on decadal and longer timescales have been the focus of significant recent research. Here we use two state-of-the-art earth system models to explore the impact of earth's mountains on the Walker circulation. When all land-surface topography is removed, the Walker circulation weakens by 33-59%. There is a ~30% decrease in global, large-scale upward vertical wind velocities in the middle of the troposphere, but only minor changes in global average convective mass flux, precipitation, surface and sea-surface temperatures. The zonally symmetric Hadley circulation is also largely unchanged. Following the spatial pattern of changes to large-scale vertical wind velocities, precipitation becomes less focused over the tropics. The weakening of the Walker circulation, but not the Hadley circulation, is similar to the behavior of climate models during radiative forcing experiments: in our simulations, the weakening is associated with changes in vertical wind velocities, rather than the hydrologic cycle. These results indicate suggest that mountain heights may significantly influence the Walker circulation on geologic time scales, and observed changes in tropical precipitation over millions of years may have been forced by changes in tropical orography.

  14. Platelet microparticles inhibit IL-17 production by regulatory T cells through P-selectin.

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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

  17. PREPARATION AND EVALUATION OF SODIUM DICLOFENAC LOADED CHITOSAN CONTROLLED RELEASE MICROPARTICLES USING FACTORIAL DESIGN

    Directory of Open Access Journals (Sweden)

    Behzad Sharif Makhmal Zadeh

    2010-09-01

    Full Text Available Sodium diclofenac is a non-steroidal anti-inflammatory drug used to relieve the inflammation, swelling, stiffness, and joint pain associated with rheumatoid arthritis. Chitosan is a linear polysaccharide derived from chitin that has been used in different pharmaceutical forms and drug delivery systems. The purpose of this study was to prepare and evaluate the chitosan beads as a controlled drug release system for sodium diclofenac consists of sustained release microparticles and immediate released particles. Sustained release chitosan microparticles were prepared with an ionic cross-linking agent. Loading efficiency was influenced by percentage of sodium polyphosphate, Tween and drug-chitosan proportion with the maximum amount of 83.12%. Release of sodium diclofenac from microparticles pattern indicated burst and sustained release that was influenced by percentage of Tween 80. Finally, Chitosan microparticles provided suitable sustained release and drug loading for sodium diclofenac oral delivery.

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

    Science.gov (United States)

    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.

  19. Optical and non-optical methods for detection and characterization of microparticles and exosomes

    NARCIS (Netherlands)

    E. van der Pol; A.G. Hoekstra; A. Sturk; C. Otto; T.G. van Leeuwen; R. Nieuwland

    2010-01-01

    Microparticles and exosomes are cell-derived microvesicles present in body fluids that play a role in coagulation, inflammation, cellular homeostasis and survival, intercellular communication, and transport. Despite increasing scientific and clinical interest, no standard procedures are available fo

  20. Multipole Electrodynamic Ion Trap Geometries for Microparticle Confinement under Standard Ambient Temperature and Pressure Conditions

    CERN Document Server

    Mihalcea, Bogdan M; Stan, Cristina; Visan, Gina T; Ganciu, Mihai; Filinov, Vladimir E; Lapitsky, Dmitry S; Deputatova, Lidiya V; Syrovatka, Roman A

    2015-01-01

    Trapping of microparticles and aerosols is of great interest for physics and chemistry. We report microparticle trapping in multipole linear Paul trap geometries, operating under Standard Ambient Temperature and Pressure (SATP) conditions. An 8-electrode and a 12-electrode linear trap geometries have been designed and tested with an aim to achieve trapping for larger number of particles and to study microparticle dynamical stability in electrodynamic fields. We report emergence of planar and volume ordered structures of the microparticles, depending on the a.c. trapping frequency and particle specific charge ratio. The electric potential within the trap was mapped using the electrolytic tank method. Particle dynamics was simulated using a stochastic Langevin equation. We emphasize extended regions of stable trapping with respect to quadrupole traps, as well as good agreement between experiment and numerical simulations.

  1. Volumetric initiation of gaseous detonation by radiant heating of suspended microparticles

    Science.gov (United States)

    Efremov, V. P.; Ivanov, M. F.; Kiverin, A. D.; Yakovenko, I. S.

    2016-02-01

    The concept of detonation wave initiation in the local volume of a fuel-gas mixture containing suspended chemically neutral microparticles heated by radiant energy from an external source is proposed. Mechanisms of initiation of the combustion and detonation waves in a region of accumulation of the radiation- heated microparticles have been studied by numerical simulation methods. Criteria that determine geometric dimensions of a region of the two-phase medium, which are necessary for the initiation of detonation waves, are formulated.

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

    Science.gov (United States)

    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.

  3. Study of nimesulide release from ethylcellulose microparticles and drug-polymer compatibility analysis

    OpenAIRE

    Khan, Shujaat A.; Ahmad, Mahmood; Aamir, Muhammad N.; Murtaza, Ghulam; Rasool, Fatima; Akhtar, Muhammad

    2010-01-01

    The aim of this study was to formulate ethyl cellulose (EC) microparticles for sustained release of nimesulide and study the effect of processing variables, drug to polymer ratio and also study the drug polymer compatibility. The microparticles were prepared by coacervation (temperature change) technique. Physical properties, such as particle size, entrapment efficiency, release pattern and morphological characteristics were investigated by in vitro dissolution, SEM, FTIR, XRD, DSC and TGA in...

  4. Chitosan-DNA microparticles as mucosal delivery system:synthesis, characterization and release in vitro

    Institute of Scientific and Technical Information of China (English)

    LI Yu-hong; FAN Min-wen; BIAN Zhuan; CHEN Zhi; ZHANG Qi; YANG Hai-rui

    2005-01-01

    Background Mucosal immunity is important to defense against dental caries. To enhance mucosal immunity, a DNA vaccine mucosal delivery system was prepared by encapsulating anticaries DNA vaccine (plasmid pGJA-P/VAX) in chitosan under optimal conditions and the characteristics of the microparticles was investigated. Furthermore, the release properties and protective action of microparticles for plasmid were studied in vitro.Methods Plasmid loaded chitosan microparticles were prepared by complex coacervation. Three factors, concentration of DNA, sodium sulfate, and the chitosan/DNA ratios in complexes [better expressed as N/P ratio: the number of poly nitrogen (N) per DNA phosphate (P)] influencing preparation were optimized by orthogonal test. The characteristics of microparticles were evaluated by scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM). DNA release rate of microparticles in similar gastro fluid (SGF) or similar intestinal fluid (SIF) at 37℃ was determined by ultraviolet spectrophotometry.Results High encapsulation efficiency (96.8%) was obtained with chitosan microparticles made under optimal conditions of 50 mmol/L Na2SO4, 200 μg/ml DNA and N/P ratio of 4. The size of particles was about 4 to 6 μm. The encapsulation process did not destroy the integrity of DNA. When incubated with SIL, after a release of about 10% in the first 60 minutes, no further DNA was released during the following 180 minutes. When incubated with SGL, the microparticles released a small burst (about 11%) in the first 60 minutes, and then slowly released at a constant, but different rate.Conclusions These chitosan microparticles showed suitable characteristics in vitro for mucosal vaccination and are therefore a promising carrier system for DNA vaccine mucosal delivery.

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

    Science.gov (United States)

    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.

  6. DNA hybridization on microparticles: determining capture-probe density and equilibrium dissociation constants.

    OpenAIRE

    Wilkins Stevens, P; Henry, M. R.; Kelso, D M

    1999-01-01

    Many DNA-probe assays utilize oligonucleotide-coated microparticles for capture of complementary nucleic acids from solution. During development of these assays, as well as in other particle-based nucleic acid applications, it is useful to know both the amount of duplex formation expected under various experimental conditions and the coating density of the capture oligonucleotide on the particle surface. We examined the simplest form of a DNA-probe microparticle assay: hybridization of a part...

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

    Science.gov (United States)

    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

  8. Uniform Chitosan Microparticles Prepared by a Novel Spray-Drying Technique

    OpenAIRE

    Wenjie Liu; Winston Duo Wu; Cordelia Selomulya; Xiao Dong Chen

    2011-01-01

    Particle size and morphology are important properties of pharmaceutical particles. Preparation of microparticles with uniform particle size and morphology is necessary in order to systematically relate these properties to the release behavior and other functionalities such as drug encapsulation and dissolution. In this study, we successfully prepared monodisperse, nonagglomerated chitosan microparticles in a single step by a novel spray-drying technique. The control of particle size and morph...

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

    Science.gov (United States)

    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. PMID:27421102

  10. Formulation of inhalable lipid-based salbutamol sulfate microparticles by spray drying technique

    OpenAIRE

    Daman, Zahra; Gilani, Kambiz; Rouholamini Najafabadi, Abdolhossein; Eftekhari, Hamid Reza; Barghi, Mohammad Ali

    2014-01-01

    Background The aim of this work was to develop dry powder inhaler (DPI) formulations of salbutamol sulfate (SS) by the aid of solid lipid microparticles (SLmPs), composed of biocompatible phospholipids or cholesterol. Methods The SLmPs were prepared by using two different solvent systems (ethanol and water-ethanol) and lipid carriers (dipalmitoylphosphatidylcholine (DPPC) and cholesterol) with/without L-leucine in the spray drying process. The spray-dried microparticles were physically-mixed ...

  11. Rapid and selective concentration of microparticles in an optoelectrofluidic platform.

    Science.gov (United States)

    Hwang, Hyundoo; Park, Je-Kyun

    2009-01-21

    We demonstrate rapid manipulation and selective concentration of microparticles using AC electrokinetics such as dielectrophoresis (DEP) and AC electro-osmosis (ACEO) in an optoelectrofluidic platform based on a liquid crystal display (LCD). When 10 V bias at 10 kHz was applied to the optoelectrofluidic device, only the 1 microm-diameter polystyrene particles were concentrated into the projected LCD image patterns and closely packed, forming the crystalline structure by ACEO flow, while the 6 microm-diameter particles were repelled by negative DEP forces. We have characterized this frequency-dependency of the optoelectrofluidic particle behavior according to the particle diameter. On the basis of these results, we can rapidly concentrate the 1 microm-diameter particles and separate them from the 6 microm particles, by applying an AC signal of 10 kHz frequency. This novel technique can be applied to rapidly concentrate, separate and pattern micro-/nanoparticles in many biological and chemical applications. PMID:19107274

  12. Grain size record of microparticles in the Muztagata ice core

    Institute of Scientific and Technical Information of China (English)

    WU; Guangjian; YAO; Tandong; XU; Baiqin; LI; Zheng; TIAN; Lide; DUAN; Keqin; WEN; Linke

    2006-01-01

    The dust transport and sediment characteristics are discussed based on analysis of microparticle size and size distribution in the Muztagata ice core at 6350 m a.s.l. The finer particles with diameter of 1―5μm are the dominant fraction in number, while middle and coarse particles mainly contribute to the total volume. The lognormal distribution characteristics can be seen for some high concentration samples, showing that model size and standard variation are greater than that in the Greenland ice cores. However, size-volume distribution of some low concentration samples is abnormal. Those distributions reflect the dust deposit process in high mountain glaciers at mid-low latitudes and show differences from those in polar ice sheet.

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

    Science.gov (United States)

    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.

  14. Numerical Simulation of Single Microparticle Trajectory in an Electrodynamic Balance

    Institute of Scientific and Technical Information of China (English)

    冯昭华; 朱家骅; 杨雪峰; 夏素兰; 关国强; DavisE.J.

    2004-01-01

    By introducing Oseen's formula to describe the viscous drag force, a more complete motion equation for a charged microparticle levitated in an electrodynamic balance (EDB) has been put forward and solved numerically by the classic Runge-Kutta method in this paper. The theoretical results have firstly demonstrated the existence of the particle oscillations and their characteristics, especially of the springpoint oscillation at large amplitude .And through the comparisons of theoretical and experimental trajectories, the adopted motion equation has proved to be able to rigorously describe the particle motion in non-Stokes region--the shape of trajectory and frequencycharacteristics are fairlv consistent and the deviations of amnliturla c~n n~llzll~r ho lo~ th~n 1cIfr/~

  15. Investigation of Water Absorption and Diffusion in Microparticles Containing Xylitol to Provide a Cooling Effect by Thermal Analysis

    Science.gov (United States)

    Salaün, F.; Bedek, G.; Devaux, E.; Dupont, D.; Deranton, D.

    2009-08-01

    Polyurethane microparticles containing xylitol as a sweat sensor system were prepared by interfacial polymerization. The structural and thermal properties of the resultant microparticles were studied. The surface morphology and chemical structure of microparticles were investigated using an optical microscope (OM) and a Fourier-transform infrared spectroscope (FTIR), respectively. The thermal properties of samples were investigated by thermogravimetric analysis (TGA) and by differential scanning calorimetry (DSC). Thus, two types of microparticles were synthesized by varying the percentage of monomers introduced. The obtained morphology is directly related to the synthesis conditions. DSC analysis indicated that the mass content of crystalline xylitol was up to 63.8 %, which resulted in a high enthalpy of dilution of 127.7 J · g-1. Furthermore, the water release rate monitored by TGA analysis was found to be faster from the microparticles than from raw xylitol. Thus, the microparticles could be applied for thermal energy storage and moisture sensor enhancement.

  16. Starch, inulin and maltodextrin as encapsulating agents affect the quality and stability of jussara pulp microparticles.

    Science.gov (United States)

    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.

  17. Porous antioxidant polymer microparticles as therapeutic systems for the airway inflammatory diseases.

    Science.gov (United States)

    Jeong, Dahee; Kang, Changsun; Jung, Eunkyeong; Yoo, Donghyuck; Wu, Dongmei; Lee, Dongwon

    2016-07-10

    Inhaling steroidal anti-inflammatory drugs is the most common treatment for airway inflammatory diseases such as asthma. However, frequent steroid administration causes adverse side effects. Therefore, the successful clinical translation of numerous steroidal drugs greatly needs pulmonary drug delivery systems which are formulated from biocompatible and non-immunogenic polymers. We have recently developed a new family of biodegradable polymer, vanillyl alcohol-containing copolyoxalate (PVAX) which is able to scavenge hydrogen peroxide and exert potent antioxidant and anti-inflammatory activity. In this work, we report the therapeutic potential of porous PVAX microparticles which encapsulate dexamethasone (DEX) as a therapeutic system for airway inflammatory diseases. PVAX microparticles themselves reduced oxidative stress and suppressed the expression of pro-inflammatory tumor necrosis factor-alpha and inducible nitric oxide synthase in the lung of ovalbumin-challenged asthmatic mice. However, DEX-loaded porous PVAX microparticles showed significantly enhanced therapeutic effects than PVAX microparticles, suggesting the synergistic effects of PVAX with DEX. In addition, PVAX microparticles showed no inflammatory responses to lung tissues. Given their excellent biocompatibility and intrinsic antioxidant and anti-inflammatory activity, PVAX microparticles hold tremendous potential as therapeutic systems for the treatment of airway inflammatory diseases such as asthma. PMID:27151077

  18. Functionalized Raspberry-Like Microparticles obtained by Assembly of Nanoparticles during Electrospraying

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Eun Chul; Jeong, Unyong [Hanyang Univ., Seoul (Korea, Republic of); Hwang, Yoon Kyun [Yonsei Univ., Seoul (Korea, Republic of)

    2014-06-15

    The present study suggests a novel method to produce raspberry-like microparticles containing diverse functional materials inside. The raspberry-like microparticles were produced from a random assembly of uniformly-sized poly(methyl methacrylate) (PMMA) nanoparticles via electrospraying. The solution containing the PMMA nanoparticles were supplied through the inner nozzle and compressed air was emitted through the outer nozzle. The air supply helped fast evaporation of acetone, so it enabled copious amount of microparticles as dry powder. The microparticles were highly porous both on the surface and interiors, hence various materials with a function of UV-blocking (TiO{sub 2} nanoparticles and methoxyphenyl triazine) or anti-aging (ethyl(4-(2,3-dihydro-1H-indene-5-carboxyamido) benzoate)) were loaded in large amount (17 wt % versus PMMA). The surface and interior structures of the microparticles were dependent on the characteristics of functional materials. The results clearly suggest that the process to prepare the raspberry-like microparticles can be an excellent approach to generate functional microstructures.

  19. Starch, inulin and maltodextrin as encapsulating agents affect the quality and stability of jussara pulp microparticles.

    Science.gov (United States)

    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. Control of Alginate Core Size in Alginate-Poly (Lactic-Co-Glycolic) Acid Microparticles

    Science.gov (United States)

    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 %.

  1. Preparation of Starch/Gelatin Blend Microparticles by a Water-in-Oil Emulsion Method for Controlled Release Drug Delivery

    OpenAIRE

    Theeraphol Phromsopha; Yodthong Baimark

    2014-01-01

    Information on the preparation and properties of starch/gelatin blend microparticles with and without crosslinking for drug delivery is presented. The blend microparticles were prepared by the water-in-oil emulsion solvent diffusion method. Glutaraldehyde and methylene blue were used as the crosslinker and the water-soluble drug model, respectively. The blend microparticles were characterized by scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, and UV-Vis spe...

  2. Preparation of Biocatalytic Microparticles by Interfacial Self-Assembly of Enzyme-Nanoparticle Conjugates Around a Cross-Linkable Core.

    Science.gov (United States)

    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. Aerosol-Assisted Fast Formulating Uniform Pharmaceutical Polymer Microparticles with Variable Properties toward pH-Sensitive Controlled Drug Release

    Directory of Open Access Journals (Sweden)

    Hong Lei

    2016-05-01

    Full Text Available Microencapsulation is highly attractive for oral drug delivery. Microparticles are a common form of drug carrier for this purpose. There is still a high demand on efficient methods to fabricate microparticles with uniform sizes and well-controlled particle properties. In this paper, uniform hydroxypropyl methylcellulose phthalate (HPMCP-based pharmaceutical microparticles loaded with either hydrophobic or hydrophilic model drugs have been directly formulated by using a unique aerosol technique, i.e., the microfluidic spray drying technology. A series of microparticles of controllable particle sizes, shapes, and structures are fabricated by tuning the solvent composition and drying temperature. It is found that a more volatile solvent and a higher drying temperature can result in fast evaporation rates to form microparticles of larger lateral size, more irregular shape, and denser matrix. The nature of the model drugs also plays an important role in determining particle properties. The drug release behaviors of the pharmaceutical microparticles are dependent on their structural properties and the nature of a specific drug, as well as sensitive to the pH value of the release medium. Most importantly, drugs in the microparticles obtained by using a more volatile solvent or a higher drying temperature can be well protected from degradation in harsh simulated gastric fluids due to the dense structures of the microparticles, while they can be fast-released in simulated intestinal fluids through particle dissolution. These pharmaceutical microparticles are potentially useful for site-specific (enteric delivery of orally-administered drugs.

  4. Microparticles containing guaraná extract obtained by spray-drying technique: development and characterization

    Directory of Open Access Journals (Sweden)

    Traudi Klein

    2015-06-01

    Full Text Available AbstractGuaraná (Paullinia cupana Kunth, Sapindaceae is well known for its dietary and pharmaceutical potential, and the semipurified extract of guaraná shows antidepressant and panicolytic effects. However, the low solubility, bioavailability and stability of the semipurified extract limit its use as a component of pharmaceutical agents. Delivery of the semipurified extract in a microparticle form could help to optimize its stability. In this study, microparticles containing semipurified extract of guaraná were obtained by the spray-drying technique, using a combination of maltodextrin and gum arabic. The raw materials and microparticles produced were characterized by particle size analysis, differential scanning calorimetry, thermogravimetric analysis, and scanning electron microscopy. The drug content and antioxidant capacity were also evaluated. In vitrodissolution tests using flow cell dissolution apparatus, were carried out to investigate the influence of formulation parameters on the release of semipurified extract of guaraná from the microparticles. The spray-drying technique and the processing conditions selected gave satisfactory encapsulation efficiency (80–110% and product yield (55–60%. The mean diameter of microparticles was around 4.5 µm. The DPPH radical scavenging capacity demonstrated that microparticles can protect the semipurified extract of guaraná from the effect of high temperatures during the process maintained the antioxidant capacity. Differential scanning calorimetry results indicated an interaction between semipurified extract of guaraná and gum arabic: maltodextrin in the microparticles, and thermogravimetric analysis indicate that the profile curves of the microparticles are similar to the adjuvants used in drying, probably due to the higher proportion of adjuvants compared to semipurified extract of guaraná. In vitro dissolution tests demonstrate that all formulations complete dissolution within 60 min

  5. Gaussian Fibonacci Circulant Type Matrices

    Directory of Open Access Journals (Sweden)

    Zhaolin Jiang

    2014-01-01

    Full Text Available Circulant matrices have become important tools in solving integrable system, Hamiltonian structure, and integral equations. In this paper, we prove that Gaussian Fibonacci circulant type matrices are invertible matrices for n>2 and give the explicit determinants and the inverse matrices. Furthermore, the upper bounds for the spread on Gaussian Fibonacci circulant and left circulant matrices are presented, respectively.

  6. Drying Using Supercritical Fluid Technology as a Potential Method for Preparation of Chitosan Aerogel Microparticles.

    Science.gov (United States)

    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.

  7. Drug release mechanisms of chemically cross-linked albumin microparticles: effect of the matrix erosion.

    Science.gov (United States)

    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

  8. Circulant Double Coverings of a Circulant Graph of Valency Five

    Institute of Scientific and Technical Information of China (English)

    Rong Quan FENG; Jin Ho KWAK

    2007-01-01

    Enumerating the isomorphism classes of several types of graph covering projections is one of the central research topics in enumerative topological graph theory. A covering of G is called circulant if its covering graph is circulant. Recently, the authors [Discrete Math., 277, 73-85 (2004)]enumerated the isomorphism classes of circulant double coverings of a certain type, called a typicalcovering, and showed that no double covering of a circulant graph of valency three is circulant. Also, in [Graphs and Combinatorics, 21, 386-400 (2005)], the isomorphism classes of circulant double coverings of a circulant graph of valency four are enumerated. In this paper, the isomorphism classes of circulant double coverings of a circulant graph of valency five are enumerated.

  9. PULMONARY CIRCULATION AT EXERCISE

    OpenAIRE

    R. Naeije; CHESLER, N

    2012-01-01

    The pulmonary circulation is a high flow and low pressure circuit, with an average resistance of 1 mmHg.min.L−1 in young adults, increasing to 2.5 mmHg.min.L−1 over 4–6 decades of life. Pulmonary vascular mechanics at exercise are best described by distensible models. Exercise does not appear to affect the time constant of the pulmonary circulation or the longitudinal distribution of resistances. Very high flows are associated with high capillary pressures, up to a 20–25 mmHg threshold associ...

  10. Impact of cross-linking and drying method on drug delivery performance of casein-pectin microparticles.

    Science.gov (United States)

    Marreto, Ricardo N; Ramos, Monica F S; Silva, Emmanuelle J; de Freitas, Osvaldo; de Freitas, Luís A P

    2013-09-01

    Pectin is a heteropolysaccharide which has been investigated for the development of colon-specific drug delivery systems. Polymers have been associated with pectin to reduce its aqueous solubility and improve the performance of drug delivery systems. Pectin-casein interaction is widely known in food research, but it has not been fully considered by pharmaceutical scientists. Thus, this study investigated the potential of casein-pectin microparticles as a drug delivery system and clarified the impact of cross-linking and drying methods on the in vitro release of indomethacin (IND) or acetaminophen (PCT) from microparticles. Microparticles were prepared by coacervation and dried by spray or spouted bed methods. Drug recovery, in vitro drug release, size, morphology, and the thermal and diffractometric properties of dried microparticles were determined. Spray-dried non-cross-linked microparticles were able to prolong IND release, and pectin was still degraded by pectinolytic enzymes. On the other hand, glutaraldehyde cross-linking prevented the enzymatic breakdown of pectin without improving IND release. Spouted bed drying reduced IND recovery from all microparticles when compared with spray drying, thus the successful spouted bed drying of microparticles depends on the chemical characteristics of both the drug and the polymer. Release data from PCT microparticles suggested that the microparticle formulation should be improved to bring about a more efficient delivery of water-soluble drugs. In conclusion, casein-pectin microparticles show great potential as a drug delivery system because casein reduces the water solubility of pectin. The drying method and cross-linking process had significant effects on the in vitro performance of these microparticles. PMID:23934432

  11. Endothelial Microparticles Act as Novel Diagnostic and Therapeutic Biomarkers of Diabetes and Its Complications: A Literature Review

    Science.gov (United States)

    Deng, Fan

    2016-01-01

    Diabetes mellitus- (DM-) related vascular diseases attract increased attention due to their high morbidity and mortality. The incidence of obesity, atherosclerosis, coronary heart disease, hypertension, and dyslipidemia is significantly higher in DM patients, with an earlier onset and faster progression compared with non-DM patients. DM-related vascular diseases including macrovascular and microvascular complications are characterized by endothelial dysfunction. Therefore, a better understanding of the etiology and mechanisms of endothelial dysfunction is important for the diagnosis and treatment of DM. Endothelial microparticles (EMPs) are new diagnostic and therapeutic targets and biomarkers in DM-related vascular disease. Circulating EMPs containing biologically active substances act as intercellular signals under physiological and pathological conditions. They serve as biological markers of altered vascular endothelium and reflect the pathological progression and diminished endothelial function of blood vessels. Recent evidence suggests that the plasma level of EMPs is significantly higher in DM patients than in healthy population and is significantly correlated with DM-related complications. These observations have prompted speculation that EMPs play a crucial role in the pathophysiology of DM. This review summarizes the known and potential roles of EMPs in the diagnosis, staging, treatment, and clinical prognosis of DM and related vascular diseases. PMID:27803933

  12. Platelet CD36 mediates interactions with endothelial cell–derived microparticles and contributes to thrombosis in mice

    Science.gov (United States)

    Ghosh, Arunima; Li, Wei; Febbraio, Maria; Espinola, Ricardo G.; McCrae, Keith R.; Cockrell, Erin; Silverstein, Roy L.

    2008-01-01

    CD36 is a scavenger receptor that binds multiple ligands, including phosphatidyl serine (PS). Although CD36– mice do not have a bleeding diathesis, we show here that they do have significantly prolonged thrombotic occlusion times in response to FeCl3-induced vascular injury. Because cell-derived microparticles (MPs) are generated in response to vascular injury and circulate in patients with prothrombotic diseases, we hypothesized that PS exposed on their surfaces could be an endogenous CD36 ligand that transmits an activating signal to platelets. We found that MPs prepared from human ECs, monocytes, or platelets or isolated from blood of normal subjects bound to platelets. Binding was not observed with platelets from CD36– donors and was inhibited by an anti-CD36 antibody or by blockade of exposed PS by annexin V or anti-PS IgM. Preincubation of platelets with MPs led to CD36-dependent augmentation of platelet activation in response to low doses of ADP, as assessed by measuring α2bβ3 activation, P-selectin expression, and aggregation. Immunofluorescence confocal microscopy of murine carotid thrombi from CD36– mice showed a significant decrement in endothelial antigen accumulation, which suggests that CD36 plays a role in MP recruitment into thrombi. These results provide what we believe to be a novel role for CD36 in thrombosis. PMID:18431509

  13. Lab-on-chip platform for circulating tumor cells isolation

    Science.gov (United States)

    Maurya, D. K.; Fooladvand, M.; Gray, E.; Ziman, M.; Alameh, K.

    2015-12-01

    We design, develop and demonstrate the principle of a continuous, non-intrusive, low power microfluidics-based lab-ona- chip (LOC) structure for Circulating Tumor Cell (CTC) separation. Cell separation is achieved through 80 cascaded contraction and expansion microchannels of widths 60 μm and 300 μm, respectively, and depth 60 μm, which enable momentum-change-induced inertial forces to be exerted on the cells, thus routing them to desired destinations. The total length of the developed LOC is 72 mm. The LOC structure is simulated using the COMSOL multiphysics software, which enables the optimization of the dimensions of the various components of the LOC structure, namely the three inlets, three filters, three contraction and expansion microchannel segments and five outlets. Simulation results show that the LOC can isolate CTCs of sizes ranging from 15 to 30 μm with a recovery rate in excess of 90%. Fluorescent microparticles of two different sizes (5 μm and 15 μm), emulating blood and CTC cells, respectively, are used to demonstrate the principle of the developed LOC. A mixture of these microparticles is injected into the primary LOC inlet via an electronically-controlled syringe pump, and the large-size particles are routed to the primary LOC outlet through the contraction and expansion microchannels. Experimental results demonstrate the ability of the developed LOC to isolate particles by size exclusion with an accuracy of 80%. Ongoing research is focusing on the LOC design improvement for better separation efficiency and testing of biological samples for isolation of CTCs.

  14. Biosensing utilizing the motion of magnetic microparticles in a microfluidic system

    KAUST Repository

    Giouroudi, Ioanna

    2010-10-23

    The study for the design of a compact and inexpensive biosensing device, which can be operated either by primary care personnel or by patients as opposed to skilled operators, is presented. The main parts of the proposed device are a microfluidic channel, permanent magnets and functionalized magnetic microparticles. The innovative aspect of the proposed biosensing method is that it utilizes the volumetric increase of magnetic microparticles when analyte binds to their surface. Their velocity decreases drastically when they are accelerated by an externally applied magnetic force within a microfluidic channel. This effect is utilized to detect the presence of analyte e.g. microbes. Analytical calculations showed that a decrease in velocity of approximately 23% can be achieved due to the volumetric change of a magnetic microparticle of View the MathML source1μm diameter when HIV virions of approximately View the MathML source0,135μm are bound to its surface and by keeping its magnetic properties the same. Preliminary experiments were carried out utilizing superparamagnetic microparticles coated with streptavidin and polystyrene microparticles coated with biotin.

  15. Multiple unit gastroretentive drug delivery systems: a new preparation method for low density microparticles.

    Science.gov (United States)

    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.

  16. Incorporation of quercetin in lipid microparticles: effect on photo- and chemical-stability.

    Science.gov (United States)

    Scalia, Santo; Mezzena, Matteo

    2009-01-15

    Lipid microparticles loaded with the flavonoid, quercetin were developed in order to enhance its stability in topical formulations. The microparticles were produced using tristearin as the lipid material and phosphatidylcholine as the emulsifier. The obtained lipoparticles were characterized by release studies, scanning electron microscopy and powder X-ray diffractometry. The quercetin loading was 12.1% (w/w). Free or microencapsulated quercetin was introduced in a model cream formulation (oil-in-water emulsion) and irradiated with a solar simulator. The extent of photodegradation was measured by high-performance liquid chromatography. The light-induced decomposition of quercetin in the cream vehicle was markedly decreased by incorporation into the lipid microparticles (the extent of degradation was 23.1+/-3.6% for non-encapsulated quercetin compared to 11.9+/-2.5% for the quercetin-loaded microparticles) and this photostabilization effect was maintained over time. Moreover, the chemical instability of quercetin, during 3-month storage of the formulations at room temperature and in the dark, was almost completely suppressed by the lipid microparticle system. Therefore incorporation of quercetin in lipoparticles represents an effective strategy to enhance its stability in dermatological products. PMID:19042102

  17. Use of the spray chilling method to deliver hydrophobic components: physical characterization of microparticles

    Directory of Open Access Journals (Sweden)

    Izabela Dutra Alvim

    2013-02-01

    Full Text Available Food industry has been developing products to meet the demands of increasing number of consumers who are concerned with their health and who seek food products that satisfy their needs. Therefore, the development of processed foods that contain functional components has become important for this industry. Microencapsulation can be used to reduce the effects of processing on functional components and preserve their bioactivity. The present study investigated the production of lipid microparticles containing phytosterols by spray chilling. The matrices comprised mixtures of stearic acid and hydrogenated vegetable fat, and the ratio of the matrix components to phytosterols was defined by an experimental design using the mean diameters of the microparticles as the response variable. The melting point of the matrices ranged from 44.5 and 53.4 ºC. The process yield was melting point dependent; the particles that exhibited lower melting point had greater losses than those with higher melting point. The microparticles' mean diameters ranged from 13.8 and 32.2 µm and were influenced by the amount of phytosterols and stearic acid. The microparticles exhibited spherical shape and typical polydispersity of atomized products. From a technological and practical (handling, yield, and agglomeration points of view, lipid microparticles with higher melting point proved promising as phytosterol carriers.

  18. Chitosan Microparticles Intended for Anti-caries DNA Vaccine Mucosal Delivery: Synthesis, Characterization and Transfection

    Institute of Scientific and Technical Information of China (English)

    LI Yuhong; FAN Mingwen; BIAN Zhuan; CHEN Zhi; Zhang Qi

    2005-01-01

    In order to enhance the mucosal immunity of anti-caries DNA vaccine, chitosan-DNA microparticles for musocal vaccination were prepared by a coacervation method. The physicochemical structure of microparticles was investigated by a scanning electron microscope (SEM) and a cofocal laser scanning microscope (CLSM). For in-vitro studies, Hela cell was transfected by chitosan-DNA microparticles.The expression of proteins was measured by the immunohistochemical methods, and the cytotocity of chitosan in Hela cell line was determined by the MTT assay. The experimental results show that the microparticles are about 2-6 μm in size and spherical in shape. The encapsulation efficiency is 99%, and the DNA is almost captured in the micropraticles. Plasmid loaded into chitosan microparticles is distributed throughout these particles. The number of positive staining cells of chitosan-pGJA-P transfected cell is more than that of naked plasmid transfect cells, but less than that of Lipofect-DNA complex group. Chitosan was found to be less cytotoxic compared with lipofectin (p<0.01).

  19. Aceclofenac-loaded chitosan-tamarind seed polysaccharide interpenetrating polymeric network microparticles.

    Science.gov (United States)

    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.

  20. Polyamide Microparticles Containing Vitamin C by Interfacial Polymerization: An Approach by Design of Experimentation

    Directory of Open Access Journals (Sweden)

    Lionel Ripoll

    2016-11-01

    Full Text Available Vitamin C is widely use in cosmetics and pharmaceutics products for its active properties. However ascorbic acid shows unfavourable chemical instability such as oxidation leading to formulation problems. Therefore, carriers, such as micro- and nanoparticles, have been widely investigated as delivery systems for vitamin C to improve its beneficial effects in skin treatment. However, none of the previous studies have been able to produce microparticles with a high encapsulation entrapment of vitamin C. The aim of the present study is to use an experimental design to optimize the synthesis of polyamide microparticles for the delivery of ascorbic acid. The effect of four formulation parameters on microparticles properties (size and morphology, encapsulation efficiency and yield, release kinetics were investigated using a surface response design. Finally, we were able to obtain stable microparticles containing more than 65% of vitamin C. This result confirms the effectiveness of using design of experiments for the optimisation of microparticle formulation and supports the proposal of using them as candidate for the delivery of vitamin C in skin treatment.

  1. MUCOADHESIVE MICROPARTICLES OF CARBOXYMETHYL CHITOSAN FOR SITE SPECIFIC DELIVERY OF PANTOPRAZOLE: FORMULATION AND IN VITRO CHARACTERIZATION

    Directory of Open Access Journals (Sweden)

    N.A. Gujarathi*, B.R. Rane and J.K. Patel

    2012-11-01

    Full Text Available Carboxymethyl chitosan, a water soluble modified carboxymethyl substituted chitosan derivative have distinct and unique properties, rendering them effective to form selective permeable mucoadhesive film or membranes. In the formulation of chitosan microsphere an acidic environment is essentially required that may degrade acid sensitive moiety, peptide or protein drugs. Mucoadhesive microparticle of carboxymethyl chitosan was designed and developed for site specific sustained release of Pantoprazole sodium. Thus prolong the residence time at the absorption site by intimate contact with the mucus layer thereby increase bioavailability, reduce the frequency of dose administration and also prolong the drug release. The mucoadhesive microparticles were prepared by Orifice ionic gelation method using carboxymethyl chitosan in combination with Carbopol 934 and HPMC K15. Entrapment efficiency was in the range of 42.4 to 84.6 %. SEM studies revealed that microparticles were discrete, spherical and free flowing. Microparticle exhibited good mucoadhesive property in the in vitro wash off test and found that Carbopol 934 had greater mucoadhesive strength than that of HPMC K15. A sustained release of Pantoprazole sodium was obtained from mucoadhesive microparticle. Stability study of optimized batch was carried out and drug content found was retained with permissible limits and there was no significant difference in the drug content.

  2. Controlled release of verapamil hydrochloride from waxy microparticles prepared by spray congealing.

    Science.gov (United States)

    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.

  3. Porous silicon microparticles for delivery of siRNA therapeutics.

    Science.gov (United States)

    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.

  4. Governing Principles of Alginate Microparticle Synthesis with Centrifugal Forces.

    Science.gov (United States)

    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. Porous silicon microparticles for delivery of siRNA therapeutics.

    Science.gov (United States)

    Shen, Jianliang; Wu, Xiaoyan; Lee, Yeonju; Wolfram, Joy; Yang, Zhizhou; Mao, Zong-Wan; Ferrari, Mauro; Shen, Haifa

    2015-01-01

    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. PMID:25651103

  6. Solid lipid microparticles for enhanced dermal delivery of tetracycline HCl.

    Science.gov (United States)

    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

  7. Antiplatelet Agents Inhibit the Generation of Platelet-Derived Microparticles

    Science.gov (United States)

    Giacomazzi, Alice; Degan, Maurizio; Calabria, Stefano; Meneguzzi, Alessandra; Minuz, Pietro

    2016-01-01

    Platelet microparticles (PMPs) contribute to thrombogenesis but the effects of antiplatelet drugs on PMPs generation is undefined. The present study investigated the cellular events regulating PMPs shedding, testing in vitro platelet agonists and inhibitors. Platelet-rich plasma from healthy subjects was stimulated with arachidonic acid (AA), U46619, collagen type-I (10 and 1.5 μg/mL), epinephrine, ADP or TRAP-6 and pre-incubated with acetylsalicylic acid (ASA, 100 and 10 μmol/L), SQ-29,548, apyrase, PSB-0739, or eptifibatide. PMPs were detected by flow-cytometry using CD61 and annexin-V as fluorescent markers. Platelet agonists induced annexin V-positive PMPs shedding. The strongest response was to high concentration collagen. ADP-triggered PMPs shedding was dose-independent. ASA reduced PMPs induced by AA- (645, 347–2946 vs. 3061, 446–4901 PMPs/μL; median ad range, n = 9, P PMP shedding. The crucial role of the fibrinogen receptor and the collagen receptor in PMPs generation, independently of platelet aggregation, was identified. PMID:27695417

  8. Procoagulant behavior and platelet microparticle generation on nanoporous alumina.

    Science.gov (United States)

    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.

  9. Governing Principles of Alginate Microparticle Synthesis with Centrifugal Forces.

    Science.gov (United States)

    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

  10. Direct thiol-ene photocoating of polyorganosiloxane microparticles.

    Science.gov (United States)

    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

  11. Restoration of Glycemic Control in Patients with Type 2 Diabetes Following Bariatric Surgery is Associated with Reduction in Microparticles

    Science.gov (United States)

    Cheng, V.; Kashyap, S.R.; Schauer, P.R.; Kirwan, J.P.; McCrae, K.R.

    2011-01-01

    Background Microparticles bud from cellular elements during inflammation and are associated with vascular dysfunction related to type 2 diabetes. Although weight loss is known to reduce inflammation, the metabolic effects of bariatric surgery on microparticle concentration and composition are not known. Objectives To determine the effect of bariatric surgery on microparticle concentration and correlate these changes with clinical parameters. Setting Multispecialty group practice Methods We studied 14 obese subjects with type 2 diabetes two weeks before and at one and 12 months following bariatric surgery. Nine of the patients underwent Roux-en-Y gastric bypass and 5 received gastric restrictive surgery. Results One month following surgery, body mass index was reduced by ~10%, glycemic control improved dramatically (P 60% reduction in endothelial, platelet microparticles and CRP levels (P 50% reduction in monocyte microparticles compared to pre-surgery. The reduction in monocyte microparticles one month after surgery was strongly associated with the reduction in hemoglobin A1c (P < 0.05). The reduction in monocyte microparticles 12 months following surgery correlated strongly with the reduction in body mass index (P < 0.05). Conclusion The reduction in microparticles after bariatric surgery in patients with type 2 diabetes reflects an attenuation of inflammation and this mechanism may contribute to normalization of glycemic control. PMID:22093380

  12. One-Step Production of Protein-Loaded PLGA Microparticles via Spray Drying Using 3-Fluid Nozzle

    DEFF Research Database (Denmark)

    Wan, Feng; Maltesen, Morten Jonas; Andersen, Sune Klint;

    2014-01-01

    The aim of this study was to investigate the potential of using a spray-dryer equipped with a 3-fluid nozzle to microencapsulate protein drugs into polymeric microparticles.......The aim of this study was to investigate the potential of using a spray-dryer equipped with a 3-fluid nozzle to microencapsulate protein drugs into polymeric microparticles....

  13. Microparticle record in the Guliya ice core and its comparison with polar records since the last interglacial

    Institute of Scientific and Technical Information of China (English)

    WU Guangjian; YAO Tandong; L.G. Thompson; LI Zhongqin

    2004-01-01

    Based on the study of oxygen isotope and microparticle in the Guliya ice core, atmospheric dust and environmental changes in the northwest Tibetan Plateau since the last interglacial were revealed. The microparticle record indicates that Iow dust load on the Plateau in the interglacial.Particle concentration increased rapidly when the climate turned into the last glacial and reached the maximum during the MIS 4. In the Last Glacial Maximum, however, the enhancement of microparticle concentration was slight, differing to those in the Antarctic and Greenland. On the orbital timescale, both the temperature on the Tibetan Plateau and summer solar insolation in the Northern Hemisphere had their impact on the microparticle record, but the difference in phase and amplitude also existed. Though having the same dust source, microparticle records in the ice cores on the Tibetan Plateau and the Greenland seem to have different significance.

  14. Preparation and In Vitro Release of Drug-Loaded Microparticles for Oral Delivery Using Wholegrain Sorghum Kafirin Protein

    Directory of Open Access Journals (Sweden)

    Esther T. L. Lau

    2015-01-01

    Full Text Available Kafirin microparticles have been proposed as an oral nutraceutical and drug delivery system. This study investigates microparticles formed with kafirin extracted from white and raw versus cooked red sorghum grains as an oral delivery system. Targeted delivery to the colon would be beneficial for medication such as prednisolone, which is used in the management of inflammatory bowel disease. Therefore, prednisolone was loaded into microparticles of kafirin from the different sources using phase separation. Differences were observed in the protein content, in vitro protein digestibility, and protein electrophoretic profile of the various sources of sorghum grains, kafirin extracts, and kafirin microparticles. For all of the formulations, the majority of the loaded prednisolone was not released in in vitro conditions simulating the upper gastrointestinal tract, indicating that most of the encapsulated drug could reach the target area of the lower gastrointestinal tract. This suggests that these kafirin microparticles may have potential as a colon-targeted nutraceutical and drug delivery system.

  15. Erosion processes and micro-particle production in gas discharge lasers

    Energy Technology Data Exchange (ETDEWEB)

    Letardi, T.; Giordano, G. [ENEA, Centro Ricerche Frascati, Frascati, RM (Italy). Dipt. Innovazione

    1999-07-01

    The erosion processes of the cathode for pulsed excimer gas lasers are explained by comparing the initiation conditions of the pulsed excimer gas laser discharge to that of the vacuum discharge breakdown. The number of the micro-particles, generated due to the above cathode-processes, are estimated. Several possible influences of the micro-particles on performances of the gas discharge lasers are analyzed. Two methods for eliminating the micro-particles or reducing their influences are discussed. [Italian] Viene descritto, comparandolo con la scarica in vuoto, il processo di erosione del catodo di un laser ad eccimeri a scarica. Viene stimato il numero delle micro-particelle generate dal processo di scarica. Vengono analizzate le possibili influenze di tali micro-particelle sulle prestazioni dei laser a scarica. Sono presentati e discussi due possibili metodi per la eliminazione delle micro-particelle generate dalla scarica.

  16. Periodontitis as a risk factor for systemic disease: Are microparticles the missing link?

    Science.gov (United States)

    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.

  17. Elaboration of microparticles of carotenoids from natural and synthetic sources for applications in food.

    Science.gov (United States)

    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

  18. Internal structure of cesium-bearing radioactive microparticles released from Fukushima nuclear power plant

    Science.gov (United States)

    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.

  19. Fluorescent Ratiometric Indicators Based on Cu(II-Induced Changes in Poly(NIPAM Microparticle Volume

    Directory of Open Access Journals (Sweden)

    Aaron M. Jones

    2013-01-01

    Full Text Available Microparticles consisting of the thermal responsive polymer N-isopropyl acrylamide (polyNIPAM, a metal ion-binding ligand and a fluorophore pair that undergoes fluorescence resonance energy transfer (FRET have been prepared and characterized. Upon the addition of Cu(II, the microparticles swell or contract depending on whether charge is introduced or neutralized on the polymer backbone. The variation in microparticle morphology is translated into changes in emission of each fluorophore in the FRET pair. By measuring the emission intensity ratio between the FRET pair upon Cu(II addition, the concentration of metal ion in solution can be quantified. This ratiometric fluorescent indicator is the newest technique in an ongoing effort to use emission spectroscopy to monitor Cu(II thermodynamic activity in environmental water samples.

  20. Microparticle Formation and Crystallization Rate of HMX with Supercritical CO2 Antisolvent Recrystallization

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Microparticle formation and crystallization rate of 1,3,5,7-tetranitro-1,3,5,7-tetraazacyclooctane (HMX) in acetone solution using supercritical carbon dioxide antisolvent (GAS) recrystallization were studied. Scanning electronic microscopy, X-ray diffraction and infrared radiation were used to examine particle size, crystallinity and chemical structure. The results show that β-HMX microparticle in different average size (2-9.5μm) and with narrow size distribution were obtained by controlling the expansibility, expansion speed, initial concentration and temperature during recrystallization of HMX. The formation of nuclei may be a main cause of consumption of solute when the solution is expanded rapidly enough and the equilibrium concentration is lower, in which almost monodisperse microparticle can be obtained.

  1. Microparticle Formation and Crystallization Rate of HMX with Supercritical CO2 Antisolvent Recrystallization

    Institute of Scientific and Technical Information of China (English)

    蔡建国; 周展云; 邓修

    2001-01-01

    Microparticle formation and crystallization rate of 1,3,5,7-tetranitro-l,3,5,7-tetraazacyclooctane (HMX) in acetone solution using supercritical carbon dioxide antisolvent (GAS) recrystallization were studied. Scanning electronic microscopy, X-ray diffraction and infrared radiation were used to examine particle size, crystallinity and chemical structure. The results show that β-HMX microparticle in different average size (2--9.5μm) and with narrow size distribution were obtained by controlling the expansibility, expansion speed, initial concentration and temperature during recrystallization of HMX. The formation of nuclei may be a main cause of consumption of solute when the solution is expanded rapidly enough and the equilibrium concentration is lower, in which almost monodisperse microparticle can be obtained.

  2. A Technique for Measuring Microparticles in Polar Ice Using Micro-Raman Spectroscopy

    Directory of Open Access Journals (Sweden)

    Toshimitsu Sakurai

    2010-01-01

    Full Text Available We describe in detail our method of measuring the chemical forms of microparticles in polar ice samples through micro-Raman spectroscopy. The method is intended for solid ice samples, an important point because melting the ice can result in dissociation, contamination, and chemical reactions prior to or during a measurement. We demonstrate the technique of measuring the chemical forms of these microparticles and show that the reference spectra of those salts expected to be common in polar ice are unambiguously detected. From our measurements, Raman intensity of sulfate salts is relatively higher than insoluble dust due to the specific Raman scattering cross-section of chemical forms of microparticles in ice.

  3. Single-, few-, and multilayer graphene not exhibiting significant advantages over graphite microparticles in electroanalysis.

    Science.gov (United States)

    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.

  4. Enzyme encapsulation in magnetic chitosan-Fe3O4 microparticles.

    Science.gov (United States)

    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.

  5. Recombinant human elastin-like magnetic microparticles for drug delivery and targeting.

    Science.gov (United States)

    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

  6. Dynamic transformation of self-assembled structures using anisotropic magnetized hydrogel microparticles

    Science.gov (United States)

    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.

  7. Fabrication and application of porous silicon multilayered microparticles in sustained drug delivery

    Science.gov (United States)

    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.

  8. High-frequency poly(vinylidene fluoride) copolymer transducers used for spectral characterization of settled microparticles

    Science.gov (United States)

    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.

  9. Silicon microfluidic flow focusing devices for the production of size-controlled PLGA based drug loaded microparticles.

    Science.gov (United States)

    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.

  10. INTERNAL CIRCULATION ENVELOPES

    CERN Multimedia

    Mail Office

    2001-01-01

    Internal mail envelopes often finish up in large piles in certain offices, thus creating a shortage for other users of the mail service, who would be grateful if everyone with an unused stock could deposit them in their mail box, after attaching them together with an elastic band or a piece of string. The messengers will then collect them so that the Mail Office can put them back in circulation. Thank you for your understanding and collaboration.

  11. Semiconducting polypyrrole-polyacrylamide microparticles with entrapped Glucose Oxidase for application in biosensors

    Science.gov (United States)

    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.

  12. Nanoparticle-coated organic-inorganic microparticles: experimental design and gastrointestinal tolerance evaluation

    Directory of Open Access Journals (Sweden)

    Beck Ruy Carlos R.

    2006-01-01

    Full Text Available The influences of the spray-drying parameters and the type of nanoparticles (nanocapsules or nanospheres on the characteristics of nanoparticle-coated diclofenac-loaded microparticles were investigated by using a factorial design 3². Gastrointestinal tolerance following oral administration in rats was evaluated. Formulations were selected considering the best yields, the best encapsulation efficiencies and the lowest water contents, presenting surfaces completely coated by nanostructures and a decrease in the surface areas in relation to the uncoated core. In vitro drug release demonstrated the influence of the nanoparticle-coating on the dissolution profiles of diclofenac. Nanocapsule-coated microparticles presented a protective effect on the gastrointestinal mucosa.

  13. Nanoparticle-coated organic-inorganic microparticles: experimental design and gastrointestinal tolerance evaluation

    Directory of Open Access Journals (Sweden)

    Ruy Carlos R. Beck

    2006-10-01

    Full Text Available The influences of the spray-drying parameters and the type of nanoparticles (nanocapsules or nanospheres on the characteristics of nanoparticle-coated diclofenac-loaded microparticles were investigated by using a factorial design 3². Gastrointestinal tolerance following oral administration in rats was evaluated. Formulations were selected considering the best yields, the best encapsulation efficiencies and the lowest water contents, presenting surfaces completely coated by nanostructures and a decrease in the surface areas in relation to the uncoated core. In vitro drug release demonstrated the influence of the nanoparticle-coating on the dissolution profiles of diclofenac. Nanocapsule-coated microparticles presented a protective effect on the gastrointestinal mucosa.

  14. An on-line remote supervisory system for microparticles based on image analysis

    Science.gov (United States)

    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.

  15. Enhanced cell adhesion to the dimpled surfaces of golf-ball-shaped microparticles.

    Science.gov (United States)

    Lee, Joo Hyuk; Lee, Chang-Soo; Cho, Kuk Young

    2014-10-01

    Engineering surface morphology as in honeycomb-structured planar films is of great importance for providing new potential application and improved performance in biomedical fields. We demonstrate potential new applications for the uniform biocompatible golf-ball-shaped microparticles that resembles 3D feature of honeycomb-structured film. Dimple size controllable golf-ball-shaped microparticles were fabricated by microfluidic device. Surface dimples not only can act as picoliter beaker but also enhance cell adhesion without any chemical modification of the surface. PMID:25265359

  16. Carbon Microparticles from Organosolv Lignin as Filler for Conducting Poly(Lactic Acid

    Directory of Open Access Journals (Sweden)

    Janea Köhnke

    2016-05-01

    Full Text Available Carbon microparticles were produced from organosolv lignin at 2000 °C under argon atmosphere following oxidative thermostabilisation at 250 °C. Scanning electron microscopy, X-ray diffraction, small-angle X-ray scattering, and electro-conductivity measurements revealed that the obtained particles were electrically conductive and were composed of large graphitic domains. Poly(lactic acid filled with various amounts of lignin-derived microparticles showed higher tensile stiffness increasing with particle load, whereas strength and extensibility decreased. Electric conductivity was measured at filler loads equal to and greater than 25% w/w.

  17. Micro-particle filter made in SU-8 for biomedical applications

    DEFF Research Database (Denmark)

    Noeth, Nadine-Nicole; Keller, Stephan Urs; Fetz, Stefanie;

    2009-01-01

    We have integrated a micro-particle filter in a polymer cantilever to filter micro-particles from a fluid while simultaneously measuring the amount of filtered particles. In a 3,8 mum thick SU-8 cantilever a filter was integrated with pore sizes between 3 and 30 mum. The chip was inserted...... in a microfluidic system and water with differently sized polystyrene beads was pumped through the filter. Particles which are larger than the pore sizes, cannot pass the filter and will increase the flow resistance of the cantilever. With more and more captured particles the cantilever starts to deflect, which can...

  18. Measurement of small light absorption in microparticles by means of optically induced rotation

    DEFF Research Database (Denmark)

    Angelsky, O. V.; Bekshaev, A. Ya; Maksimyak, P. P.;

    2015-01-01

    The absorption parameters of micro-particles have been associated with the induced spin exerted upon the particle, when embedded in a circularly polarized coherent field. The induced rotational speed is theoretically analyzed, showing the influence of the beam parameters, the parameters of the pa......The absorption parameters of micro-particles have been associated with the induced spin exerted upon the particle, when embedded in a circularly polarized coherent field. The induced rotational speed is theoretically analyzed, showing the influence of the beam parameters, the parameters...

  19. Evaluation of cross-linked chitosan microparticles containing acyclovir obtained by spray-drying

    Energy Technology Data Exchange (ETDEWEB)

    Stulzer, Hellen Karine [Laboratorio Quitech, Departamento de Quimica, Universidade Federal de Santa Catarina (Brazil); Laboratorio de Controle de Qualidade, Departamento de Ciencias Farmaceuticas, Universidade Federal de Santa Catarina (Brazil); Laboratorio de Controle de Qualidade, Departamento de Ciencias Farmaceuticas, Universidade Estadual de Ponta Grossa (Brazil)], E-mail: hellen.stulzer@gmail.com; Tagliari, Monika Piazzon [Laboratorio de Controle de Qualidade, Departamento de Ciencias Farmaceuticas, Universidade Federal de Santa Catarina (Brazil); Parize, Alexandre Luis [Laboratorio Quitech, Departamento de Quimica, Universidade Federal de Santa Catarina (Brazil); Silva, Marcos Antonio Segatto [Laboratorio de Controle de Qualidade, Departamento de Ciencias Farmaceuticas, Universidade Federal de Santa Catarina (Brazil); Laranjeira, Mauro Cesar Marghetti [Laboratorio Quitech, Departamento de Quimica, Universidade Federal de Santa Catarina (Brazil)

    2009-03-01

    The aim of this study was to obtain microparticles containing acyclovir (ACV) and chitosan cross-linked with tripolyphosphate using the spray-drying technique. The resultant system was evaluated through loading efficiency, differential scanning calorimetry (DSC), thermogravimetric analysis (TG), X-ray powder diffraction (XRPD), scanning electron microscopy (SEM), in vitro release and stability studies. The results obtained indicated that the polymer/ACV ratio influenced the final properties of the microparticles, with higher ratios giving the best encapsulation efficiency, dissolution profiles and stability. The DSC and XRPD analyses indicated that the ACV was transformed into amorphous form during the spray-drying process.

  20. Physical and electrochemical study of cobalt oxide nano- and microparticles

    Energy Technology Data Exchange (ETDEWEB)

    Alburquenque, D. [Dpto. de Química de los Materiales, USACh, Av. L.B.O.‘Higgins 3363, 9170022 Santiago (Chile); Dpto. de Metalurgia, USACh, Av. Ecuador 3469, 9170124, Santiago (Chile); Vargas, E. [Dpto. de Física, USACh and CEDENNA, Av. Ecuador 3493, 9170124 Santiago (Chile); Dpto. de Metalurgia, USACh, Av. Ecuador 3469, 9170124, Santiago (Chile); Denardin, J.C.; Escrig, J. [Dpto. de Física, USACh and CEDENNA, Av. Ecuador 3493, 9170124 Santiago (Chile); Marco, J.F. [Instituto de Química Física “Rocasolano”, CSIC, c/Serrano 119, 28006 Madrid (Spain); Ortiz, J. [Dpto. de Química de los Materiales, USACh, Av. L.B.O.‘Higgins 3363, 9170022 Santiago (Chile); Gautier, J.L., E-mail: juan.gautier@usach.cl [Dpto. de Química de los Materiales, USACh, Av. L.B.O.‘Higgins 3363, 9170022 Santiago (Chile)

    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.

  1. Evaluation of ceftiofur–PHBV microparticles in rats

    Directory of Open Access Journals (Sweden)

    Vilos C

    2014-05-01

    the veterinary industry. Keywords: microparticles, drug delivery, Salmonella Typhimurium, rat infection model, blood parameters

  2. Microparticles of Aloe vera/vitamin E/chitosan: microscopic, a nuclear imaging and an in vivo test analysis for burn treatment.

    Science.gov (United States)

    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. PMID:24211657

  3. Modelled Circulation In Storfjorden

    Science.gov (United States)

    Skogseth, R.; Asplin, L.

    The model area Storfjorden is situated between the islands Spitsbergen, Barentsöya and Edgeöya at the Svalbard Archipelago. The entrance of Storfjorden is defined by a shallow bank Storfjordbanken and some small islands Tusenöyane in southeast, and by an 115m deep sill at about 76 45' N in the south. Maximum depth in Storfjorden is 190m, which is surrounded by gradually shallower shelves in the north, the east and southeast. A steep bottom slope is present on the western side of Storfjorden. He- leysundet and Freemansundet, two sounds between respectively Spitsbergen and Bar- entsöya, and Barentsöya and Edgeöya, define two narrow and shallow entrances in the north and northeast connecting Storfjorden with the northwestern Barents Sea. Strong tidal currents exist in Heleysundet (4-5ms-1) and Freemansundet (2-3ms-1), but the general circulation in Storfjorden is not well known. The coastal current in Storfjor- den is cyclonic directed into Storfjorden south of Edgeöya from the East Spitsbergen Current and out of Storfjorden south of Spitsbergen where it is called Sørkappstrøm- men. A three-dimensional sigma layered numerical ocean model called Bergen Ocean Model (BOM) was used to simulate the circulation in Storfjorden with Freemansundet opened. Two simulations were carried out, one with heat flux (100 Wm-2) and one without heat flux from the ocean to the atmosphere. The heat flux was applied only in the proper fjord area north of the sill and not outside as a crude approximation of the effects of a polynya in the sea ice cover during winter. Both simulations had a 4km horizontal resolution and 21 sigma layers. The model is forced by winds (from the NCEP reanalyzed fields) and tides. Initial fields are from the DNMI/IMR climatol- ogy. The model simulation without heat flux gave a circulation heavily dependent on tidal forcing, showing strong tidal currents up to 2ms-1 in Freemansundet, between Tusenöyane and on Storfjordbanken southwest of Edgeöya. Earlier

  4. Resolvability in Circulant Graphs

    Institute of Scientific and Technical Information of China (English)

    Muhammad SALMAN; Imran JAVAID; Muhammad Anwar CHAUDHRY

    2012-01-01

    A set W of the vertices of a connected graph G is called a resolving set for G if for every two distinct vertices u,v ∈ V(G) there is a vertex w ∈ W such that d(u,w) ≠ d(v,w).A resolving set of minimum cardinality is called a metric basis for G and the number of vertices in a metric basis is called the metric dimension of G,denoted by dim(G).For a vertex u of G and a subset S of V(G),the distance between u and S is the number mins∈s d(u,s).A k-partition H ={S1,S2,...,Sk} of V(G) is called a resolving partition if for every two distinct vertices u,v ∈ V(G) there is a set Si in Π such that d(u,Si) ≠ d(v,Si).The minimum k for which there is a resolving k-partition of V(G) is called the partition dimension of G,denoted by pd(G).The circulant graph is a graph with vertex set Zn,an additive group ofintegers modulo n,and two vertices labeled i and j adjacent if and only if i - j (mod n) ∈ C,where C C Zn has the property that C =-C and 0(∈) C.The circulant graph is denoted by Xn,△ where A =|C|.In this paper,we study the metric dimension of a family of circulant graphs Xn,3 with connection set C ={1,-n/2,n - 1} and prove that dim(Xn,3) is independent of choice of n by showing that 3 for all n =0 (mod 4),dim(X,n,3) ={ 4 for all n =2 (mod 4).We also study the partition dimension of a family of circulant graphs Xn,4 with connection set C ={±1,±2} and prove that pd(Xn,4) is independent of choice of n and show that pd(X5,4) =5 and 3 forall odd n≥9,pd(Xn,4) ={ 4 for all even n ≥ 6 and n =7.

  5. Diffusion loading and drug delivery characteristics of alginate gel microparticles produced by a novel impinging aerosols method.

    Science.gov (United States)

    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.

  6. Hydrothermal synthesis of cubic α-Fe2O3 microparticles using glycine: Surface characterization, reaction mechanism and electrochemical activity

    International Nuclear Information System (INIS)

    Graphical abstract: Highlights: → We synthesize cubic α-Fe2O3 (hematite) microparticles. → Their morphological, mineralogical and surface properties are determined. → Reaction mechanism based on thermodynamics and ionic equilibrium concepts are described. → Microparticles have charge capacity of 160 mAh/g and good columbic efficiency of 94%. - Abstract: Cubic α-Fe2O3 (hematite) microparticles (side lengths = 0.3-1.3 μm) have been synthesized using glycine and ferric chloride via a simple one-step hydrothermal reaction. Their morphological, mineralogical and surface properties have been determined using scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray diffractometry (XRD) and X-ray photoelectron spectroscopy (XPS). XRD analysis indicated that the synthesized α-Fe2O3 microparticles were minerallogically pure. An increase in hydrothermal reaction duration from 10 to 24 h increased the atomic percentages of α-Fe2O3 on the surface of the microparticles by almost 8%. The mechanism concerning reactions of species to produce this microparticles precipitate was elucidated based on thermodynamics and ionic equilibrium aspects. In the electrochemical analysis, the synthesized α-Fe2O3 microparticles (as cathode material) exhibit an approximate charge capacity of 160 mAh/g and excellent coulombic efficiency of 94%.

  7. Analysis of Cell-Derived Microparticles with Highly Precise Nanotechnological Methods

    DEFF Research Database (Denmark)

    Cherré, Solène; Østergaard, Ole; Heegaard, Niels H.H.;

    2014-01-01

    Cell-derived microparticles have gained a broad interest in the past years. Being released by blood cells upon activation or induction of apoptosis, they have a great potential as novel diagnostic markers and their investigation can bring new knowledge into the pathogenesis of various diseases. H...

  8. Cellular origin and procoagulant activity of tissue factor-exposing microparticles in cancer patients

    NARCIS (Netherlands)

    Kleinjan, A.; Berckmans, R.J.; Böing, A.N.; Sturk, A.; Büller, H.R.; Kamphuisen, P.W.; Nieuwland, R.

    2012-01-01

    Background: In patients with cancer, tissue factor-exposing microparticles (TF-exposing MP) have been associated with disease progression and thrombosis. The cellular origin and coagulant activity of TF-exposing MP, however, remain disputed. Therefore, we investigated the cellular origin of the TF-e

  9. Microparticles based on chitosan/carboxymethylcellulose polyelectrolyte complexes for colon delivery of vancomycin.

    Science.gov (United States)

    Cerchiara, T; Abruzzo, A; Parolin, C; Vitali, B; Bigucci, F; Gallucci, M C; Nicoletta, F P; Luppi, B

    2016-06-01

    The aim of this work was to prepare polyelectrolyte complexes based on chitosan (CH) and carboxymethylcellulose (CMC) for colon delivery of vancomycin (VM). Various batches of polyelectrolyte complexes, using three different CH/CMC weight ratios (3:1, 1:1 and 1:3), were prepared and collected as microparticles by spray-drying process. Microparticles were characterized in terms of yield, encapsulation efficiency, drug loading, morphology and mucoadhesion properties. Microparticles water-uptake and VM release as well as its protection against gastric pepsin degradation were also investigated. Finally, the antibacterial activity against Staphylococcus aureus, a Gram-positive model strain, was evaluated. The best formulation CH/CMC 1:3 was selected based on the encapsulation efficiency, water-uptake and drug release rate. Moreover, microparticles were able to prevent VM degradation and showed a good antibacterial activity against S. aureus. Finally, to improve the release of VM in the colon the selected formulation was coated with lauric acid. PMID:27083351

  10. Lysozyme-magnesium aluminum silicate microparticles: Molecular interaction, bioactivity and release studies

    DEFF Research Database (Denmark)

    Kanjanakawinkul, Watchara; Medlicott, Natalie J.; Rades, Thomas;

    2015-01-01

    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...

  11. Mechanical evaluation of implanted calcium phosphate cement incorporated with PLGA microparticles.

    NARCIS (Netherlands)

    Link, D.P.; Dolder, J. van den; Jurgens, W.J.; Wolke, J.G.C.; Jansen, J.A.

    2006-01-01

    In this study, the mechanical properties of an implanted calcium phosphate (CaP) cement incorporated with 20wt% poly (dl-lactic-co-glycolic acid) (PLGA) microparticles were investigated in a rat cranial defect. After 2, 4 and 8 weeks of implantation, implants were evaluated mechanically (push-out te

  12. MUCOADHESIVE MICROPARTICLES OF CARBOXYMETHYL CHITOSAN FOR SITE SPECIFIC DELIVERY OF PANTOPRAZOLE: FORMULATION AND IN VITRO CHARACTERIZATION

    OpenAIRE

    N.A. Gujarathi*, B.R. Rane and J.K. Patel

    2012-01-01

    Carboxymethyl chitosan, a water soluble modified carboxymethyl substituted chitosan derivative have distinct and unique properties, rendering them effective to form selective permeable mucoadhesive film or membranes. In the formulation of chitosan microsphere an acidic environment is essentially required that may degrade acid sensitive moiety, peptide or protein drugs. Mucoadhesive microparticle of carboxymethyl chitosan was designed and developed for site specific sustained release of Pantop...

  13. Release Kinetic in Yogurt from Gallic Acid Microparticles with Chemically Modified Inulin.

    Science.gov (United States)

    García, Paula; Vergara, Cristina; Robert, Paz

    2015-10-01

    Gallic acid (GA) was encapsulated with native (NIn), cross-linked (CIn) and acetylated (AIn) inulin by spray-drying. Inulin microparticles were characterized by encapsulation efficiency (EE) and their release profile in yogurt. The EE was significantly higher for GA-CIn (98%) compared with GA-NIn (81%) and GA-AIn (77%) microparticles, showing the effect of the modification of inulin on interaction of GA-polymer. GA release profile data in yogurt for GA-CIn, GA-NIn and GA-AIn were fitted to Peppas and Higuchi models in order to obtain the GA release rate constant. Although the GA release rate constants were significantly different among systems, these differences were slight and the GA release was fast (80% inulin-systems did not control GA release in yogurt. The mechanism of GA release followed a Fickian diffusion and relaxation of chains for all microparticles. According to the release profile, these microparticles would be best suited for use in instant foods.

  14. Rapid Software-Based Design and Optical Transient Liquid Molding of Microparticles.

    Science.gov (United States)

    Wu, Chueh-Yu; Owsley, Keegan; Di Carlo, Dino

    2015-12-22

    Microparticles with complex 3D shape and composition are produced using a novel fabrication method, optical transient liquid molding, in which a 2D light pattern exposes a photopolymer precursor stream shaped along the flow axis by software-aided inertial flow engineering.

  15. Magnetic-based motion control of paramagnetic microparticles with disturbance compensation

    NARCIS (Netherlands)

    Khalil, Islam S.M.; Abelmann, Leon; Misra, Sarthak

    2014-01-01

    Magnetic systems have the potential to control the motion of microparticles and microrobots during targeted drug delivery. During their manipulation, a nominal magnetic force-current map is usually derived and used as a basis of the control system design. However, the inevitable mismatch between the

  16. Gateway to understanding microparticles: standardized isolation and identification of plasma membrane-derived vesicles

    NARCIS (Netherlands)

    Dinkla, S.; Brock, R.; Joosten, I.; Bosman, G.J.C.G.M.

    2013-01-01

    Microparticles (MPs) are small plasma membrane-derived vesicles that can expose molecules originating from their parental cells. As vectors of biological information they are likely to play an active role in both homeostasis and pathogenesis, making them promising biomarkers and nanomedicine tools.

  17. On-chip bio-analyte detection utilizing the velocity of magnetic microparticles in a fluid

    KAUST Repository

    Giouroudi, Ioanna

    2011-03-22

    A biosensing principle utilizing the motion of suspended magnetic microparticles in a microfluidic system is presented. The system utilizes the innovative concept of the velocity dependence of magnetic microparticles (MPs) due to their volumetric change when analyte is attached to their surface via antibody–antigen binding. When the magnetic microparticles are attracted by a magnetic field within a microfluidic channel their velocity depends on the presence of analyte. Specifically, their velocity decreases drastically when the magnetic microparticles are covered by (nonmagnetic) analyte (LMPs) due to the increased drag force in the opposite direction to that of the magnetic force. Experiments were carried out as a proof of concept. A promising 52% decrease in the velocity of the LMPs in comparison to that of the MPs was measured when both of them were accelerated inside a microfluidic channel using an external permanent magnet. The presented biosensing methodology offers a compact and integrated solution for a new kind of on-chip analysis with potentially high sensitivity and shorter acquisition time than conventional laboratory based systems.

  18. Adsorption of methylene blue on biochar microparticles derived from different waste materials.

    Science.gov (United States)

    Lonappan, Linson; Rouissi, Tarek; Das, Ratul Kumar; Brar, Satinder K; Ramirez, Antonio Avalos; Verma, Mausam; Surampalli, Rao Y; Valero, José R

    2016-03-01

    Biochar microparticles were prepared from three different types of biochar, derived from waste materials, such as pine wood (BC-PW), pig manure (BC-PM) and cardboard (BC-PD) under various pyrolysis conditions. The microparticles were prepared by dry grinding and sequential sieving through various ASTM sieves. Particle size and specific surface area were analyzed using laser particle size analyzer. The particles were further characterized using scanning electron microscope (SEM). The adsorption capacity of each class of adsorbent was determined by methylene blue adsorption tests in comparison with commercially available activated carbon. Experimental results showed that dye adsorption increased with initial concentration of the adsorbate and biochar dosage. Biochar microparticles prepared from different sources exhibited improvement in adsorption capacity (7.8±0.5 mg g(-1) to 25±1.3 mg g(-1)) in comparison with raw biochar and commercially available activated carbon. The adsorption capacity varied with source material and method of production of biochar. The maximum adsorption capacity was 25 mg g(-1) for BC-PM microparticles at 25°C for an adsorbate concentration of 500 mg L(-1) in comparison with 48.30±3.6 mg g(-1) for activated carbon. The equilibrium adsorption data were best described by Langmuir model for BC-PM and BC-PD and Freundlich model for BC-PW. PMID:26818183

  19. Toxin-coregulated pilus-loaded microparticles as a vaccine against Vibrio cholerae O139

    Institute of Scientific and Technical Information of China (English)

    杜艳; 贾文祥; 刘莉

    2004-01-01

    @@ The cholera epidemics is an important public health problem in many developing countries. Highly effective and preventive vaccines against cholera are under investigation as alternatives to the one available presently. Much of the vaccine research focuses on colonization factors. Colonization of a human by the Vibrio cholerae (V. cholerae Ol strain is mediated by toxin-coregulated pilus (TCP), 1 which was shown to play a role in the infant mouse cholera model and subsequently in human volunteers. 2 TCP-loaded vaccines could potentially provide cross-protection among experimental strains. Data have indicated that poly (D,L-lactide)-polyethylene glycol copolymer (PELA)microparticles loaded antigens were strongly immunogenic, 3 and that these microparticles served as an effective delivery system for a single dose of vaccine. 4Microparticle formulation could represent the next generation of vaccines, as they are highly effective at delivery of vaccines, thus requiring fewer doses. 5 We prepared PELA microparticles loaded with TCP for testing as a vaccine; their targeting distributions were identified and related immune responses were analyzed.

  20. Dating Archaeological Copper/Bronze Artifacts by Using the Voltammetry of Microparticles

    OpenAIRE

    Doménech-Carbó, Antonio; Doménech-Carbó, Maria Teresa; Capelo, Sofia; Pasíes, Trinidad; Martínez-Lázaro, Isabel

    2014-01-01

    A method for dating copper/bronze archaeological objects aged in atmospheric environments is proposed based on the specific signals for cuprite and tenorite corrosion products measured through the voltammtry of microparticles method. The tenorite/cuprite ratio increased with the corrosion time and fitted to a potential law that yielded a calibration curve usable for dating purposes.

  1. Microfluidic assisted synthesis of silver nanoparticle-chitosan composite microparticles for antibacterial applications.

    Science.gov (United States)

    Yang, Chih-Hui; Wang, Lung-Shuo; Chen, Szu-Yu; Huang, Mao-Chen; Li, Ya-Hua; Lin, Yun-Chul; Chen, Pei-Fan; Shaw, Jei-Fu; Huang, Keng-Shiang

    2016-08-30

    Silver nanoparticle (Ag NP)-loaded chitosan composites have numerous biomedical applications; however, fabricating uniform composite microparticles remains challenging. This paper presents a novel microfluidic approach for single-step and in situ synthesis of Ag NP-loaded chitosan microparticles. This proposed approach enables obtaining uniform and monodisperse Ag NP-loaded chitosan microparticles measuring several hundred micrometers. In addition, the diameter of the composites can be tuned by adjusting the flow on the microfluidic chip. The composite particles containing Ag NPs were characterized using UV-vis spectra and scanning electron microscopy-energy dispersive X-ray spectrometry data. The characteristic peaks of Ag NPs in the UV-vis spectra and the element mapping or pattern revealed the formation of nanosized silver particles. The results of antibacterial tests indicated that both chitosan and composite particles showed antibacterial ability, and Ag NPs could enhance the inhibition rate and exhibited dose-dependent antibacterial ability. Because of the properties of Ag NPs and chitosan, the synthesized composite microparticles can be used in several future potential applications, such as bactericidal agents for water disinfection, antipathogens, and surface plasma resonance enhancers. PMID:26780124

  2. Immobilization of Lipases Produced by the Endophytic Fungus Cercospora kikuchii on Chitosan Microparticles

    Directory of Open Access Journals (Sweden)

    Lara Aparecida Buffoni Campos Carneiro

    2014-08-01

    Full Text Available This work studied the immobilization of Cercospora kikuchii lipases on chitosan microparticles by chemical attachment on chitosan acetate microparticles activated by glutaraldehyde (CAM added before or after the enzyme and physical adsorption on highly deacetylated chitosan hydrochloride microparticles (CHM. Lipases covalently immobilized on pre-activated CAM showed better performance retaining 88.4% of the enzymatic activity, with 68.2% of immobilization efficiency (IE. The immobilized enzyme retained an activity of about 53.5 % after five reuses, using p-NPP as substrate. Physical adsorption of lipase onto highly deacetylated CHM showed 46.2 % of enzymatic activity and 28.6% of IE. This immobilized derivative did not lose activity up to 80 days of storage at 4°C, while lipases immobilized on pre-activated CAM maintained its activity up to 180 days at same conditions. Taken together the results indicate that chitosan microparticles provide an optimal microenvironment for the immobilized enzyme to maintain good activity and stability.

  3. Coagulation activation and microparticle-associated coagulant activity in cancer patients: An exploratory prospective study

    NARCIS (Netherlands)

    van Doormaal, Frederiek F.; Kleinjan, Ankie; Berckmans, René J.; Mackman, Nigel; Manly, David; Kamphuisen, Pieter W.; Richel, Dick J.; Büller, Harry R.; Sturk, Auguste; Nieuwland, Rienk

    2012-01-01

    Cancer increases the risk of venous thromboembolism (VTE). Here, we investigated the contribution of microparticle (MP)-dependent procoagulant activity to the prothrombotic state in these patients. In 43 cancer patients without VTE at study entry and 22 healthy volunteers, markers of in vivo and MP-

  4. Size dependent microbial oxidation and reduction of magnetite nano- and micro-particles

    DEFF Research Database (Denmark)

    Byrne, James M; van der Laan, Gerrit; Figueroa, Adriana I;

    2016-01-01

    or that of whole particles. Here we examine this issue for the phototrophic Fe(II)-oxidizing bacteria Rhodopseudomonas palustris TIE-1 and the Fe(III)-reducing bacteria Geobacter sulfurreducens, comparing magnetite nanoparticles (d ≈ 12 nm) against microparticles (d ≈ 100-200 nm). By integrating surface...

  5. Effect of crosslink density on the water-binding capacity of whey protein microparticles

    NARCIS (Netherlands)

    Peters, J.P.C.M.; Luyten, H.; Alting, A.C.; Boom, R.M.; Goot, van der A.J.

    2015-01-01

    The ability of whey protein microparticles (MPs) to bind water and consequently to swell is, amongst others, determined by the crosslink density of the MPs. The Flory-Rehner model states that a decrease in crosslink density should lead to an increased swelling of the MPs. Decreasing the crosslink de

  6. North Atlantic Circulation

    Science.gov (United States)

    Molinari, R.; Bryan, K.; Schott, F.

    The intensity of the North Atlantic winddriven and thermohaline circulation and the close proximity of many oceanographic installations make the North Atlantic a particularly favored region of the world ocean from the standpoint of research in ocean circulation. Recent increases in available data and advances in numerical modeling techniques served as the impetus to convene a joint workshop of modelers and observers working on the North Atlantic with the Scientific Committee on Oceanic Research (SCOR) Working Group (WG) 68 (“North Atlantic Circulation”). Goals of the workshop were to provide an update on data sets and models and to discuss the poleward heat flux problem and possible monitoring strategies. The joint Workshop/SCOR WG-68 meeting was convened by F. Schott (chairman of the working group; Rosenstiel School of Marine and Atmospheric Science, Miami, Fla.), K. Bryan (National Oceanic and Atmospheric Administration/ Geophysical Fluid Dynamics Laboratory (NOAA/GFDL)), and R. Molinari (NOAA/Atlantic Oceanographic and Meteorological Laboratory (NOAA/AOML)).

  7. Circulation of Stars

    Science.gov (United States)

    Boitani, P.

    2016-01-01

    Since the dawn of man, contemplation of the stars has been a primary impulse in human beings, who proliferated their knowledge of the stars all over the world. Aristotle sees this as the product of primeval and perennial “wonder” which gives rise to what we call science, philosophy, and poetry. Astronomy, astrology, and star art (painting, architecture, literature, and music) go hand in hand through millennia in all cultures of the planet (and all use catasterisms to explain certain phenomena). Some of these developments are independent of each other, i.e., they take place in one culture independently of others. Some, on the other hand, are the product of the “circulation of stars.” There are two ways of looking at this. One seeks out forms, the other concentrates on the passing of specific lore from one area to another through time. The former relies on archetypes (for instance, with catasterism), the latter constitutes a historical process. In this paper I present some of the surprising ways in which the circulation of stars has occurred—from East to West, from East to the Far East, and from West to East, at times simultaneously.

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

    Directory of Open Access Journals (Sweden)

    Tobar-Grande B

    2013-05-01

    Full Text Available Blanca Tobar-Grande,1 Ricardo Godoy,1 Paulina Bustos,2 Carlos von Plessing,1 Elias Fattal,3,4 Nicolas Tsapis,3,4 Claudia Olave,1 Carolina Gómez-Gaete11Departamento de Farmacia, Facultad de Farmacia, Universidad de Concepción, Concepción, Chile; 2Departamento de Bioquímica Clínica e Inmunología, Facultad de Farmacia, Universidad de Concepción, Concepción, Chile; 3Univ Paris-Sud, Institut Galien Paris-Sud, Faculté de Pharmacie, Châtenay-Malabry, France; 4CNRS, UMR 8612, Faculté de Pharmacie, Châtenay-Malabry, FranceAbstract: 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-1ß, 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

  9. Activity of daptomycin- and vancomycin-loaded poly-epsilon-caprolactone microparticles against mature staphylococcal biofilms

    Directory of Open Access Journals (Sweden)

    Santos Ferreira I

    2015-07-01

    Full Text Available Inês Santos Ferreira,1 Ana F Bettencourt,1 Lídia MD Gonçalves,1 Stefanie Kasper,2 Bertrand Bétrisey,3 Judith Kikhney,2 Annette Moter,2 Andrej Trampuz,4 António J Almeida1 1Research Institute for Medicines (iMed.ULisboa, Faculty of Pharmacy, University of Lisbon, Lisbon, Portugal; 2Biofilmcenter, German Heart Institute Berlin, Berlin, Germany; 3Infectious Diseases Service, Department of Medicine, Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland; 4Center for Musculoskeletal Surgery, Charité – University Medicine Berlin, Berlin, Germany Abstract: 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

  10. UNS S31603 Stainless Steel Tungsten Inert Gas Welds Made with Microparticle and Nanoparticle Oxides

    Directory of Open Access Journals (Sweden)

    Kuang-Hung Tseng

    2014-06-01

    Full Text Available The purpose of this study was to investigate the difference between tungsten inert gas (TIG welding of austenitic stainless steel assisted by microparticle oxides and that assisted by nanoparticle oxides. SiO2 and Al2O3 were used to investigate the effects of the thermal stability and the particle size of the activated compounds on the surface appearance, geometric shape, angular distortion, delta ferrite content and Vickers hardness of the UNS S31603 stainless steel TIG weld. The results show that the use of SiO2 leads to a satisfactory surface appearance compared to that of the TIG weld made with Al2O3. The surface appearance of the TIG weld made with nanoparticle oxide has less flux slag compared with the one made with microparticle oxide of the same type. Compared with microparticle SiO2, the TIG welding with nanoparticle SiO2 has the potential benefits of high joint penetration and less angular distortion in the resulting weldment. The TIG welding with nanoparticle Al2O3 does not result in a significant increase in the penetration or reduction of distortion. The TIG welding with microparticle or nanoparticle SiO2 uses a heat source with higher power density, resulting in a higher ferrite content and hardness of the stainless steel weld metal. In contrast, microparticle or nanoparticle Al2O3 results in no significant difference in metallurgical properties compared to that of the C-TIG weld metal. Compared with oxide particle size, the thermal stability of the oxide plays a significant role in enhancing the joint penetration capability of the weld, for the UNS S31603 stainless steel TIG welds made with activated oxides.

  11. Ocean General Circulation Models

    Energy Technology Data Exchange (ETDEWEB)

    Yoon, Jin-Ho; Ma, Po-Lun

    2012-09-30

    1. Definition of Subject The purpose of this text is to provide an introduction to aspects of oceanic general circulation models (OGCMs), an important component of Climate System or Earth System Model (ESM). The role of the ocean in ESMs is described in Chapter XX (EDITOR: PLEASE FIND THE COUPLED CLIMATE or EARTH SYSTEM MODELING CHAPTERS). The emerging need for understanding the Earth’s climate system and especially projecting its future evolution has encouraged scientists to explore the dynamical, physical, and biogeochemical processes in the ocean. Understanding the role of these processes in the climate system is an interesting and challenging scientific subject. For example, a research question how much extra heat or CO2 generated by anthropogenic activities can be stored in the deep ocean is not only scientifically interesting but also important in projecting future climate of the earth. Thus, OGCMs have been developed and applied to investigate the various oceanic processes and their role in the climate system.

  12. Percutaneous interventions in Fontan circulation

    Directory of Open Access Journals (Sweden)

    Eduardo Franco

    2015-09-01

    Conclusions: Interventional catheterization procedures are often necessary to reach and maintain the fragile Fontan circulation, mainly in patients with right morphology systemic ventricles and fenestrated Fontan conduits.

  13. Toxicodynamics of Rigid Polystyrene Microparticles on Pulmonary Gas Exchange in Mice: Implications for Microemboli-based Drug Delivery Systems

    Science.gov (United States)

    Kutscher, HL.; Gao, D.; Li, S.; Massa, CB.; Cervelli, J.; Deshmukh, M.; Joseph, LB.; Laskin, DL.; Sinko, PJ.

    2013-01-01

    The toxicodynamic relationship between the number and size of pulmonary microemboli resulting from uniformly sized, rigid polystyrene microparticles (MPs) administered intravenously and their potential effects on pulmonary gas exchange was investigated. CD-1 male mice (6–8 wk) were intravenously administered 10, 25 and 45 μm diameter MPs. Oxygen hemoglobin saturation in the blood (SpO2) was measured non-invasively using a pulse oximeter while varying inhaled oxygen concentration (FIO2). Resulting data were fit to a physiologically based non-linear mathematical model that estimates 2 parameters: ventilation-perfusion ratio (VA/Q) and shunt (percentage of deoxygenated blood returning to systemic circulation). The number of MPs administered prior to a statistically significant reduction in normalized VA/Q was dependent on particle size. MP doses that resulted in a significant reduction in normalized VA/Q one day post-treatment were 4,000, 40,000 and 550,000 MPs/g for 45, 25 and 10 μm MPs, respectively. The model estimated VA/Q and shunt returned to baseline levels 7 days post-treatment. Measuring SpO2 alone was not sufficient to observe changes in gas exchange; however, when combined with model-derived VA/Q and shunt early reversible toxicity from pulmonary microemboli was detected suggesting that the model and physical measurements are both required for assessing toxicity. Moreover, it appears that the MP load required to alter gas exchange in a mouse prior to lethality is significantly higher than the anticipated required MP dose for effective drug delivery. Overall, the current results indicate that the microemboli-based approach for targeted pulmonary drug delivery is potentially safe and should be further explored. PMID:23142466

  14. Toxicodynamics of rigid polystyrene microparticles on pulmonary gas exchange in mice: implications for microemboli-based drug delivery systems.

    Science.gov (United States)

    Kutscher, H L; Gao, D; Li, S; Massa, C B; Cervelli, J; Deshmukh, M; Joseph, L B; Laskin, D L; Sinko, P J

    2013-01-15

    The toxicodynamic relationship between the number and size of pulmonary microemboli resulting from uniformly sized, rigid polystyrene microparticles (MPs) administered intravenously and their potential effects on pulmonary gas exchange were investigated. CD-1 male mice (6-8 weeks) were intravenously administered 10, 25 and 45 μm diameter MPs. Oxygen hemoglobin saturation in the blood (SpO(2)) was measured non-invasively using a pulse oximeter while varying inhaled oxygen concentration (F(I)O(2)). The resulting data were fit to a physiologically based non-linear mathematical model that estimates 2 parameters: ventilation-perfusion ratio (V(A)/Q) and shunt (percentage of deoxygenated blood returning to systemic circulation). The number of MPs administered prior to a statistically significant reduction in normalized V(A)/Q was dependent on particle size. MP doses that resulted in a significant reduction in normalized V(A)/Q one day post-treatment were 4000, 40,000 and 550,000 MPs/g for 45, 25 and 10 μm MPs, respectively. The model estimated V(A)/Q and shunt returned to baseline levels 7 days post-treatment. Measuring SpO(2) alone was not sufficient to observe changes in gas exchange; however, when combined with model-derived V(A)/Q and shunt early reversible toxicity from pulmonary microemboli was detected suggesting that the model and physical measurements are both required for assessing toxicity. Moreover, it appears that the MP load required to alter gas exchange in a mouse prior to lethality is significantly higher than the anticipated required MP dose for effective drug delivery. Overall, the current results indicate that the microemboli-based approach for targeted pulmonary drug delivery is potentially safe and should be further explored. PMID:23142466

  15. Critical solvent properties affecting the particle formation process and characteristics of celecoxib-loaded PLGA microparticles via spray-drying

    DEFF Research Database (Denmark)

    Wan, Feng; Bohr, Adam; Maltesen, Morten Jonas;

    2013-01-01

    power of the feed solution. An obvious burst release was observed for the microparticles prepared by the feed solutions with the highest amount of poor solvent for PLGA. TGA analysis revealed distinct drying kinetics for the binary mixtures. CONCLUSIONS: The particle formation process is mainly governed......) microparticles prepared by spray-drying. METHODS: Binary mixtures of acetone and methanol at different molar ratios were applied to dissolve celecoxib and PLGA prior to spray-drying. The resulting microparticles were characterized with respect to morphology, texture, surface chemistry, solid state properties...... by the PLGA precipitation rate, which is solvent-dependent, and the migration rate of celecoxib molecules during drying. The texture and surface chemistry of the spray-dried PLGA microparticles can therefore be tailored by adjusting the solvent composition....

  16. A facile method of fabricating mechanical durable anti-icing coatings based on CeO2 microparticles

    Science.gov (United States)

    Wang, Pengren; Peng, Chaoyi; Wu, Binrui; Yuan, Zhiqing; Yang, Fubiao; Zeng, Jingcheng

    2015-07-01

    Compromising between hydrophobicity and mechanical durability may be a feasible approach to fabricating usable anti-icing coatings. This work improves the contact angle of current commercial anti-icing coatings applied to wind turbine blades dramatically and keeps relatively high mechanical durability. CeO2 microparticles and diluent were mixed with fluorocarbon resin to fabricate high hydrophobic coatings on the glass fiber reinforced epoxy composite substrates. The proportion of CeO2 microparticles and diluent influences the contact angles significantly. The optimum mass ratio of fluorocarbon resin to CeO2 microparticles to diluent is 1:1.5:1, which leads to the highest contact angle close to 140°. The microscopy analysis shows that the CeO2 microparticles form nano/microscale hierarchical structure on the surface of the coatings.

  17. Neutron Activated Samarium-153 Microparticles for Transarterial Radioembolization of Liver Tumour with Post-Procedure Imaging Capabilities

    Science.gov (United States)

    Hashikin, Nurul Ab. Aziz; Yeong, Chai-Hong; Abdullah, Basri Johan Jeet; Ng, Kwan-Hoong; Chung, Lip-Yong; Dahalan, Rehir; Perkins, Alan Christopher

    2015-01-01

    Introduction Samarium-153 (153Sm) styrene divinylbenzene microparticles were developed as a surrogate for Yttrium-90 (90Y) microspheres in liver radioembolization therapy. Unlike the pure beta emitter 90Y, 153Sm possess both therapeutic beta and diagnostic gamma radiations, making it possible for post-procedure imaging following therapy. Methods The microparticles were prepared using commercially available cation exchange resin, Amberlite IR-120 H+ (620–830 μm), which were reduced to 20–40 μm via ball mill grinding and sieve separation. The microparticles were labelled with 152Sm via ion exchange process with 152SmCl3, prior to neutron activation to produce radioactive 153Sm through 152Sm(n,γ)153Sm reaction. Therapeutic activity of 3 GBq was referred based on the recommended activity used in 90Y-microspheres therapy. The samples were irradiated in 1.494 x 1012 n.cm-2.s-1 neutron flux for 6 h to achieve the nominal activity of 3.1 GBq.g-1. Physicochemical characterisation of the microparticles, gamma spectrometry, and in vitro radiolabelling studies were carried out to study the performance and stability of the microparticles. Results Fourier Transform Infrared (FTIR) spectroscopy of the Amberlite IR-120 resins showed unaffected functional groups, following size reduction of the beads. However, as shown by the electron microscope, the microparticles were irregular in shape. The radioactivity achieved after 6 h neutron activation was 3.104 ± 0.029 GBq. The specific activity per microparticle was 53.855 ± 0.503 Bq. Gamma spectrometry and elemental analysis showed no radioactive impurities in the samples. Radiolabelling efficiencies of 153Sm-Amberlite in distilled water and blood plasma over 48 h were excellent and higher than 95%. Conclusion The laboratory work revealed that the 153Sm-Amberlite microparticles demonstrated superior characteristics for potential use in hepatic radioembolization. PMID:26382059

  18. TNF-α Blocker Effect of Naringenin-Loaded Sericin Microparticles that Are Potentially Useful in the Treatment of Psoriasis

    OpenAIRE

    Theodora Chlapanidas; Sara Perteghella; Flavio Leoni; Silvio Faragò; Mario Marazzi; Daniela Rossi; Emanuela Martino; Raffaella Gaggeri; Simona Collina

    2014-01-01

    This study aims to evaluate the effect of combined use of the racemic flavanone Naringenin (NRG) and the protein sericin as TNF-α blockers. Sericin (SMs) and (R/S) NRG-loaded Sericin (SNRGMs) microparticles were prepared by spray-drying, characterized in terms of morphology and particle size distribution, and encapsulation efficiency was determined. Concerning morphology and particle size distribution of microparticles, results indicated that they were not affected by the presence of NRG. Th...

  19. Neutron Activated Samarium-153 Microparticles for Transarterial Radioembolization of Liver Tumour with Post-Procedure Imaging Capabilities.

    Directory of Open Access Journals (Sweden)

    Nurul Ab Aziz Hashikin

    Full Text Available Samarium-153 (153Sm styrene divinylbenzene microparticles were developed as a surrogate for Yttrium-90 (90Y microspheres in liver radioembolization therapy. Unlike the pure beta emitter 90Y, 153Sm possess both therapeutic beta and diagnostic gamma radiations, making it possible for post-procedure imaging following therapy.The microparticles were prepared using commercially available cation exchange resin, Amberlite IR-120 H+ (620-830 μm, which were reduced to 20-40 μm via ball mill grinding and sieve separation. The microparticles were labelled with 152Sm via ion exchange process with 152SmCl3, prior to neutron activation to produce radioactive 153Sm through 152Sm(n,γ153Sm reaction. Therapeutic activity of 3 GBq was referred based on the recommended activity used in 90Y-microspheres therapy. The samples were irradiated in 1.494 x 10(12 n.cm(-2.s(-1 neutron flux for 6 h to achieve the nominal activity of 3.1 GBq.g(-1. Physicochemical characterisation of the microparticles, gamma spectrometry, and in vitro radiolabelling studies were carried out to study the performance and stability of the microparticles.Fourier Transform Infrared (FTIR spectroscopy of the Amberlite IR-120 resins showed unaffected functional groups, following size reduction of the beads. However, as shown by the electron microscope, the microparticles were irregular in shape. The radioactivity achieved after 6 h neutron activation was 3.104 ± 0.029 GBq. The specific activity per microparticle was 53.855 ± 0.503 Bq. Gamma spectrometry and elemental analysis showed no radioactive impurities in the samples. Radiolabelling efficiencies of 153Sm-Amberlite in distilled water and blood plasma over 48 h were excellent and higher than 95%.The laboratory work revealed that the 153Sm-Amberlite microparticles demonstrated superior characteristics for potential use in hepatic radioembolization.

  20. Fabrication and characterization of a novel microparticle with gyrus-patterned surface and growth factor delivery for cartilage tissue engineering

    International Nuclear Information System (INIS)

    Microparticles can serve as substrates for cell amplification and deliver the expanded cells to the site of the defect. It was hypothesized that a novel microparticle combined of sustained and localized delivery of proliferative growth factors and gyrus-patterned surface would influence the cell behaviours of adherence and expansion on the microparticle in the present study. To test the hypothesis, gelatin particles with diameter ranging from 280 to 350 μm were fabricated and were modified by cryogenic freeze-drying treatment and basic fibroblast growth factor (bFGF) incorporation. The results of in vitro chondrocyte culture illustrated that cells could proliferate more obviously on the microparticles with bFGF addition, but no correlation between attachment rate and bFGF was observed. On the other hand, microparticles with gyrus-patterned surface demonstrated the highest cell attachment rate and higher rate of cell growth, in particular on bFGF combined ones. It seems to be a promising candidate as a chondrocyte microparticle and could be the potential application in cartilage tissue engineering.

  1. Cetirizine dihydrochloride loaded microparticles design using ionotropic cross-linked chitosan nanoparticles by spray-drying method.

    Science.gov (United States)

    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 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.

  2. Fabrication and characterization of a novel microparticle with gyrus-patterned surface and growth factor delivery for cartilage tissue engineering

    Energy Technology Data Exchange (ETDEWEB)

    Huang Sha [Department of Oral Histology and Pathology, School of Stomatology, Fourth Military Medical University, Xi' an 710032 (China); Research and Development Center for Tissue Engineering, Fourth Military Medical University, Xi' an 710032 (China); Wang Yijuan [Key Laboratory for Macromolecular Science of Shaanxi Province, Shaanxi Normal University, Xi' an 710062 (China); Liang Tang [Department of Oral Histology and Pathology, School of Stomatology, Fourth Military Medical University, Xi' an 710032 (China); Research and Development Center for Tissue Engineering, Fourth Military Medical University, Xi' an 710032 (China); Jin Fang [Department of Orthodontics, School of Stomatology, Fourth Military Medical University, Xi' an 710032 (China); Liu Shouxin [Key Laboratory for Macromolecular Science of Shaanxi Province, Shaanxi Normal University, Xi' an 710062 (China); Jin Yan, E-mail: yanjin@fmmu.edu.cn [Department of Oral Histology and Pathology, School of Stomatology, Fourth Military Medical University, Xi' an 710032 (China); Research and Development Center for Tissue Engineering, Fourth Military Medical University, Xi' an 710032 (China)

    2009-05-05

    Microparticles can serve as substrates for cell amplification and deliver the expanded cells to the site of the defect. It was hypothesized that a novel microparticle combined of sustained and localized delivery of proliferative growth factors and gyrus-patterned surface would influence the cell behaviours of adherence and expansion on the microparticle in the present study. To test the hypothesis, gelatin particles with diameter ranging from 280 to 350 {mu}m were fabricated and were modified by cryogenic freeze-drying treatment and basic fibroblast growth factor (bFGF) incorporation. The results of in vitro chondrocyte culture illustrated that cells could proliferate more obviously on the microparticles with bFGF addition, but no correlation between attachment rate and bFGF was observed. On the other hand, microparticles with gyrus-patterned surface demonstrated the highest cell attachment rate and higher rate of cell growth, in particular on bFGF combined ones. It seems to be a promising candidate as a chondrocyte microparticle and could be the potential application in cartilage tissue engineering.

  3. Sino-Danish Brain Circulation

    DEFF Research Database (Denmark)

    Bertelsen, Rasmus Gjedssø; Du, Xiangyun; Søndergaard, Morten Karnøe

    2014-01-01

    China is faced with urgent needs to develop an economically and environmentally sustainable economy based on innovation and knowledge. Brain circulation and research and business investments from the outside are central for this development. Sino-American brain circulation and research...... and investment by overseas researchers and entrepreneurs are well described. In that case, the US is the center of global R&D and S&T. However, the brain circulation and research and investments between a small open Scandinavian economy, such as Denmark, and the huge developing economy of China are not well...... understood. In this case, Denmark is very highly developed, but a satellite in the global R&D and S&T system. With time and the growth of China as a R&D and S&T power house, both Denmark and China will benefit from brain circulation between them. Such brain circulation is likely to play a key role in flows...

  4. TROPICAL METEOROLOGY & Climate: Hadley Circulation

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Jian; Vecchi, Gabriel A.

    2015-01-30

    The Hadley circulation, a prominent circulation feature characterized by rising air near the Equator and sinking air in the subtropics, defines the position of dry subtropical areas and is a fundamental regulator of the earth’s energy and momentum budgets. The character of the Hadley circulation, and its related precipitation regimes, exhibits variation and change in response to both climate variability and radiative forcing changes. The strength and position of the Hadley circulation change from year to year paced by El Niño and La Niña events. Over the last few decades of the twentieth century, the Hadley cell has expanded poleward in both hemispheres, with changes in atmospheric composition (including stratospheric ozone depletion and greenhouse gas increases) thought to have contributed to its expansion. This article introduces the basic phenomenology and driving mechanism of the Hadley circulation and discusses its variations under both natural and anthropogenic climate forcings.

  5. STUDY OF STABILITY AND EXPIRATION DATE ESTABLISHIMENT OF MICROPARTICLES OF ALPRAZOLAM ON THE BASIS OF POLY-D,L-LACTIDE-CO-GLYCOLIDE

    Directory of Open Access Journals (Sweden)

    A. I. Medvetskiy

    2014-01-01

    Full Text Available Stability of microparticles of alprazolam in natural conditions was studied by the method of "accelerated aging". It was established that microparticles of alprazolam were not exposed to disruption and their appearance was not altered during the research. Expiration dates of alprazolam microparticles determination was calculated using the formula of J.H. van't Hoff. The expiration date made 2 years.

  6. Microparticles, soil, derived chemical components and sea salt in the Hans Tausen Ice Cap ice core from Peary Island, North Greenland

    DEFF Research Database (Denmark)

    Steffensen, J.P.; Andersen, M.L.S; Stampe, Mia;

    2001-01-01

    Selected segments of the 344 m deep ice core from Hans Tausen ice cap in Peary Land, North Greenland have been stratigraphically analyzed for chemical impurities and insoluble microparticles (Dust). Two different components of the microparticles have been identified by their different sizedistrib......Selected segments of the 344 m deep ice core from Hans Tausen ice cap in Peary Land, North Greenland have been stratigraphically analyzed for chemical impurities and insoluble microparticles (Dust). Two different components of the microparticles have been identified by their different...

  7. Molecular detection of bacterial pathogens using microparticle enhanced double-stranded DNA probes.

    Science.gov (United States)

    Riahi, Reza; Mach, Kathleen E; Mohan, Ruchika; Liao, Joseph C; Wong, Pak Kin

    2011-08-15

    Rapid, specific, and sensitive detection of bacterial pathogens is essential toward clinical management of infectious diseases. Traditional approaches for pathogen detection, however, often require time-intensive bacterial culture and amplification procedures. Herein, a microparticle enhanced double-stranded DNA probe is demonstrated for rapid species-specific detection of bacterial 16S rRNA. In this molecular assay, the binding of the target sequence to the fluorophore conjugated probe thermodynamically displaces the quencher probe and allows the fluorophore to fluoresce. By incorporation of streptavidin-coated microparticles to localize the biotinylated probes, the sensitivity of the assay can be improved by 3 orders of magnitude. The limit of detection of the assay is as few as eight bacteria without target amplification and is highly specific against other common pathogens. Its applicability toward clinical diagnostics is demonstrated by directly identifying bacterial pathogens in urine samples from patients with urinary tract infections.

  8. Poly(N-vinylcaprolactam-co-methacrylic acid) hydrogel microparticles for oral insulin delivery.

    Science.gov (United States)

    Mundargi, Raghavendra C; Rangaswamy, Vidhya; Aminabhavi, Tejraj M

    2011-01-01

    pH-sensitive copolymeric hydrogels prepared from N-vinylcaprolactam and methacrylic acid monomers by free radical polymerization offered 52% encapsulation efficiency and evaluated for oral delivery of human insulin. The in vitro experiments performed on insulin-loaded microparticles in pH 1.2 media (stomach condition) demonstrated no release of insulin in the first 2 h, but almost 100% insulin was released in pH 7.4 media (intestinal condition) in 6 h. The carrier was characterized by Fourier transform infrared, differential scanning calorimeter, thermogravimetry and nuclear magnetic resonance techniques to confirm the formation of copolymer, while scanning electron microscopy was used to assess the morphology of hydrogel microparticles. The in vivo experiments on alloxan-induced diabetic rats showed the biological inhibition up to 50% and glucose tolerance tests exhibited 44% inhibition. The formulations of this study are the promising carriers for oral delivery of insulin.

  9. Iontophoresis of minoxidil sulphate loaded microparticles, a strategy for follicular drug targeting?

    Science.gov (United States)

    Gelfuso, Guilherme M; Barros, M Angélica de Oliveira; Delgado-Charro, M Begoña; Guy, Richard H; Lopez, Renata F V

    2015-10-01

    The feasibility of targeting drugs to hair follicles by a combination of microencapsulation and iontophoresis has been evaluated. Minoxidil sulphate (MXS), which is used in the treatment of alopecia, was selected as a relevant drug with respect to follicular penetration. The skin permeation and disposition of MXS encapsulated in chitosan microparticles (MXS-MP) was evaluated in vitro after passive and iontophoretic delivery. Uptake of MXS was quantified at different exposure times in the stratum corneum (SC) and hair follicles. Microencapsulation resulted in increased (6-fold) drug accumulation in the hair follicles relative to delivery from a simple MXS solution. Application of iontophoresis enhanced follicular delivery for both the solution and the microparticle formulations. It appears, therefore, that microencapsulation and iontophoresis can act synergistically to enhance topical drug targeting to hair follicles.

  10. Slowdown of microparticles by an electromagnetic potential well deepening over time

    CERN Document Server

    Izmailov, Azad Ch

    2016-01-01

    We analyze possible motion control of microparticles by means of external electromagnetic fields which induce potential wells having fixed spatial distribution but deepening over time up to some limit. It is assumed that given particles are under conditions of the high vacuum and forces acting on these particles are not dissipative. We have established slowdown of comparatively fast particles as a result of their transit through considered potential wells. This process is demonstrated on example of the nonresonance laser beam with the intensity amplifying over time. More detailed research of particle slowdown in such electromagnetic fields is carried out on the basis of simple analytical relationships obtained from basic equations of classical mechanics for the model of the one-dimensional rectangular potential well deepening over time. Method for cooling of particles, demonstrated in the present work, may be applied for essential increase of spectroscopy resolution of various microparticles, including in def...

  11. Stabilisation effects of superparamagnetic nanoparticles on clustering in nanocomposite microparticles and on magnetic behaviour

    Science.gov (United States)

    Mandel, K.; Hutter, F.; Gellermann, C.; Sextl, G.

    2013-04-01

    Superparamagnetic nanoparticles of magnetite were coprecipitated from iron salts, dispersed with nitric acid and stabilised either by lactic acid (LA) or by a polycarboxylate-ether polymer (MELPERS4343, MP). The differently stabilised nanoparticles were incorporated into a silica matrix to form nanocomposite microparticles. The silica matrix was prepared either from tetraethylorthosilicate (TEOS) or from an aqueous sodium silicate (water glass) solution. Stabilisation of nanoparticles had a crucial influence on microparticle texture and nanoparticle distribution in the silica matrix. Magnetic measurements in combination with transmission electron microscopy (TEM) investigations suggest a uniform magnetic interaction of nanoparticles in case of LA stabilisation and magnetically interacting nanoparticle clusters of different sizes in case of MP stabilisation. Splitting of blocking temperature (TB) and irreversible temperature (Tir) in zero field cooled (ZFC) and field cooled (FC) measurements is discussed in terms of nanoparticle clustering.

  12. Photocatalytic degradation of RhB and TNT and photocatalytic water splitting with CZTS microparticles

    Science.gov (United States)

    Shinde, S. S.

    2015-07-01

    Cu2ZnSnS4 (CZTS) is a main candidate material for solar energy conversion through both photovoltaics and photocatalysis based on environmentally friendly elements and with a direct band gap of 1.5 eV. We report the synthesis of quasi Cu2ZnSnS4 microparticles with unprecedented narrow size distributions. The structural, morphological and core level analysis has been carried out by XRD, SEM and XPS techniques. These microparticles have shown excellent photocatalytic activity toward degradation of Rhodamine B dye (RhB) and TNT under visible light. The extent of mineralization has been analyzed by COD and TOC values. Photocatalytic water splitting for H2 generation has also been reported.

  13. Iontophoresis of minoxidil sulphate loaded microparticles, a strategy for follicular drug targeting?

    Science.gov (United States)

    Gelfuso, Guilherme M; Barros, M Angélica de Oliveira; Delgado-Charro, M Begoña; Guy, Richard H; Lopez, Renata F V

    2015-10-01

    The feasibility of targeting drugs to hair follicles by a combination of microencapsulation and iontophoresis has been evaluated. Minoxidil sulphate (MXS), which is used in the treatment of alopecia, was selected as a relevant drug with respect to follicular penetration. The skin permeation and disposition of MXS encapsulated in chitosan microparticles (MXS-MP) was evaluated in vitro after passive and iontophoretic delivery. Uptake of MXS was quantified at different exposure times in the stratum corneum (SC) and hair follicles. Microencapsulation resulted in increased (6-fold) drug accumulation in the hair follicles relative to delivery from a simple MXS solution. Application of iontophoresis enhanced follicular delivery for both the solution and the microparticle formulations. It appears, therefore, that microencapsulation and iontophoresis can act synergistically to enhance topical drug targeting to hair follicles. PMID:26222406

  14. An on-line remote supervisory system for microparticles based on image analysis

    Institute of Scientific and Technical Information of China (English)

    LIU Wei-hua; JIANG Ming-shun; SUI Qing-mei

    2011-01-01

    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 wansmit 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.

  15. Large-Angle Bending Transport of Microparticles by Acoustic Half-Bessel Beams

    CERN Document Server

    Li, Yixiang; Xu, Shengjun; Ke, Manzhu; Liu, Zhengyou

    2014-01-01

    Conventional microparticle transports by light or sound are realized along a straight line. Recently, this limit has been overcome in optics as the growing up of the self-accelerating Airy beams, which are featured by many peculiar properties, e.g., bending propagation, diffraction-free and self-healing. However, the bending angles of Airy beams are rather small since they are only paraxial solutions of the two-dimensional (2D) Helmholtz equation. Here we propose a novel micromanipulation by using acoustic Half-Bessel beams, which are strict solutions of the 2D Helmholtz equation. Compared with that achieved by Airy beams, the bending angle of the particle trajectory attained here is much steeper (exceeding 90o). The large-angle bending transport of microparticles, which is robust to complex scattering environment, enables a wide range of applications from the colloidal to biological sciences.

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

    Directory of Open Access Journals (Sweden)

    Benpeng Zhu

    2016-03-01

    Full Text Available 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.

  17. Gas-dynamic explosion of water microparticles under action high-power femtosecond laser pulses

    Science.gov (United States)

    Zemlyanov, Alexander A.; Geints, Yuri E.; Apeksimov, Dmitrii V.

    2006-02-01

    Among the broad audience of problems of atmospheric nonlinear optics the important place is occupied with a problem about interaction of intensive laser radiation with water microparticles. Drops, being in a field of powerful light radiation, owing to effects of evaporation or explosion change the optical characteristics and influence on the optical properties of an environment. It results to that process and the distribution of intensive laser radiation in a particle is characterized by self-influence and is capable to change the internal power of a drop due to occurrence of areas of optical breakdown. In the report the model of destruction of water microparticles under action of supershort laser radiation is submitted. The physical contents of model is the effect of shock boiling up of a liquid at it gas-dynamic expansion from areas subject to optical breakdown.

  18. TGF-beta1 release from biodegradable polymer microparticles: its effects on marrow stromal osteoblast function

    Science.gov (United States)

    Lu, L.; Yaszemski, M. J.; Mikos, A. G.; McIntire, L. V. (Principal Investigator)

    2001-01-01

    BACKGROUND: Controlled release of transforming growth factor-beta1 (TGF-beta1) to a bone defect may be beneficial for the induction of a bone regeneration cascade. The objectives of this work were to assess the feasibility of using biodegradable polymer microparticles as carriers for controlled TGF-beta1 delivery and the effects of released TGF-beta1 on the proliferation and differentiation of marrow stromal cells in vitro. METHODS: Recombinant human TGF-beta1 was incorporated into microparticles of blends of poly(DL-lactic-co-glycolic acid) (PLGA) and poly(ethylene glycol) (PEG). Fluorescein isothiocynate-labeled bovine serum albumin (FITC-BSA) was co-encapsulated as a porogen. The effects of PEG content (0, 1, or 5% by weight [wt%]) and buffer pH (3, 5, or 7.4) on the protein release kinetics and the degradation of PLGA were determined in vitro for as long as 28 days. Rat marrow stromal cells were seeded on a biodegradable poly(propylene fumarate) (PPF) substrate. The dose response and biological activity of released TGF-beta1 was determined after 3 days in culture. The effects of TGF-beta1 released from PLGA/PEG microparticles on marrow stromal cell proliferation and osteoblastic differentiation were assessed during a 21-day period. RESULTS: TGF-beta1 was encapsulated along with FITC-BSA into PLGA/PEG blend microparticles and released in a multiphasic fashion including an initial burst for as long as 28 days in vitro. Increasing the initial PEG content resulted in a decreased cumulative mass of released proteins. Aggregation of FITC-BSA occurred at lower buffer pH, which led to decreased release rates of both proteins. The degradation of PLGA was increased at higher PEG content and significantly accelerated at acidic pH conditions. Rat marrow stromal cells cultured on PPF substrates showed a dose response to TGF-beta1 released from the microparticles similar to that of added TGF-beta1, indicating that the activity of TGF-beta1 was retained during microparticle

  19. Procoagulant, tissue factor-bearing microparticles in bronchoalveolar lavage of interstitial lung disease patients: an observational study.

    Directory of Open Access Journals (Sweden)

    Federica Novelli

    Full Text Available Coagulation factor Xa appears involved in the pathogenesis of pulmonary fibrosis. Through its interaction with protease activated receptor-1, this protease signals myofibroblast differentiation in lung fibroblasts. Although fibrogenic stimuli induce factor X synthesis by alveolar cells, the mechanisms of local posttranslational factor X activation are not fully understood. Cell-derived microparticles are submicron vesicles involved in different physiological processes, including blood coagulation; they potentially activate factor X due to the exposure on their outer membrane of both phosphatidylserine and tissue factor. We postulated a role for procoagulant microparticles in the pathogenesis of interstitial lung diseases. Nineteen patients with interstitial lung diseases and 11 controls were studied. All subjects underwent bronchoalveolar lavage; interstitial lung disease patients also underwent pulmonary function tests and high resolution CT scan. Microparticles were enumerated in the bronchoalveolar lavage fluid with a solid-phase assay based on thrombin generation. Microparticles were also tested for tissue factor activity. In vitro shedding of microparticles upon incubation with H₂O₂ was assessed in the human alveolar cell line, A549 and in normal bronchial epithelial cells. Tissue factor synthesis was quantitated by real-time PCR. Total microparticle number and microparticle-associated tissue factor activity were increased in interstitial lung disease patients compared to controls (84±8 vs. 39±3 nM phosphatidylserine; 293±37 vs. 105±21 arbitrary units of tissue factor activity; mean±SEM; p<.05 for both comparisons. Microparticle-bound tissue factor activity was inversely correlated with lung function as assessed by both diffusion capacity and forced vital capacity (r² = .27 and .31, respectively; p<.05 for both correlations. Exposure of lung epithelial cells to H₂O₂ caused an increase in microparticle-bound tissue factor

  20. Injectable Sustained Release Microparticles of Curcumin: A New Concept for Cancer Chemoprevention

    OpenAIRE

    Shahani, Komal; Swaminathan, Suresh Kumar; Freeman, Diana; Blum, Angela; Ma, Linan; Panyam, Jayanth

    2010-01-01

    Poor oral bioavailability limits the use of curcumin and other dietary polyphenols in the prevention and treatment of cancer. Minimally invasive strategies that can provide effective and sustained tissue concentrations of these agents will be highly valuable tools in the fight against cancer. The objective of this study was to investigate the use of an injectable sustained release microparticle formulation of curcumin as a novel approach to breast cancer chemoprevention. A biodegradable and b...

  1. Chelators influenced synthesis of chitosan-carboxymethyl cellulose microparticles for controlled drug delivery

    Science.gov (United States)

    Samrot, Antony V.; Akanksha; Jahnavi, Tatipamula; Padmanaban, S.; Philip, Sheryl-Ann; Burman, Ujjala; Rabel, Arul Maximus

    2016-07-01

    In this study, polyphenolic curcumin is entrapped within microcomposites made of biopolymers chitosan (CS) and carboxymethyl cellulose (CMC) formulated by ionic gelation method. Here, different concentrations of two chelating agents, barium chloride and sodium tripolyphosphate, are used to make microcomposites. Thus, the synthesized microparticles were characterized by FTIR, and their surface morphology was studied by SEM. Drug encapsulation efficiency and the drug release kinetics of CS-CMC composites are also studied. The produced microcomposites were used to study antibacterial activity in vitro.

  2. Preparation, characterization and antimicrobial activity of chitosan microparticles with thyme essential oil

    Directory of Open Access Journals (Sweden)

    Pecarski Danijela

    2014-01-01

    Full Text Available Considering the therapeutic effects of formulations with violate essential oils, development of an available drug delivery system is of great interest, especially assuming the fact that using essential oils as antimicrobial agents is a rather expanded in antimicrobial therapy nowadays. In this work, chitosan microparticles with encapsulated thyme essential oil were prepared by the emulsion cross-linking method. The effect of thyme oil and glutaraldehyde initial concentrations on particle size, morphology, and particle size distribution was investigated. In addition, the influence of these parameters on the encapsulation of thyme oil in chitosan microparticles, concerning thyme oil loadings and encapsulation efficiency was also tested. The particles showed a spherical shape with an average diameter from 4.71±1.42 to 13.65±4.34 m, depending on the concentration of the essential oil and glutaraldehyde that were used. The diameter of microparticles appeared to increase with increasing the thyme essential oil concentration, and decreased with the increase of glutaraldehyde concentration. It was shown that the concentration of glutaraldehyde did not affect the degree of encapsulation, but the increase in the initial concentration of thyme oil increased the degree of encapsulation of this essential oil in chitosan microparticles. All particles containing thyme essential oil, as well as essential oil of thyme itself showed significant antimicrobial activity against Staphylococcus aureus ATCC 25923, Esherichia coli ATCC 25922, Candida albicans ATCC 24433, Enterococcus faecalis ATCC 25929. This study showed a great potential of the use of thyme essential oil as an antimicrobial agent, especially when encapsulated in a drug delivery system with controlled release of the active antimicrobial component.

  3. Light-induced rotations of chiral birefringent microparticles in optical tweezers

    Science.gov (United States)

    Donato, M. G.; Mazzulla, A.; Pagliusi, P.; Magazzù, A.; Hernandez, R. J.; Provenzano, C.; Gucciardi, P. G.; Maragò, O. M.; Cipparrone, G.

    2016-09-01

    We study the rotational dynamics of solid chiral and birefringent microparticles induced by elliptically polarized laser light in optical tweezers. We find that both reflection of left circularly polarized light and residual linear retardance affect the particle dynamics. The degree of ellipticity of laser light needed to induce rotations is found. The experimental results are compared with analytical calculations of the transfer of angular moment from elliptically polarized light to chiral birefringent particles.

  4. Magnetic microparticles post-synthetically coated by hyaluronic acid as an enhanced carrier for microfluidic bioanalysis

    Energy Technology Data Exchange (ETDEWEB)

    Holubova, Lucie [Department of Biological and Biochemical Sciences, Faculty of Chemical Technology, University of Pardubice, Studentska 573, 53210 Pardubice (Czech Republic); Department of Analytical Chemistry, Faculty of Chemical Technology, University of Pardubice, Studentska 573, 53210 Pardubice (Czech Republic); Knotek, Petr [Joint Laboratory of Solid State Chemistry, Faculty of Chemical Technology, University of Pardubice, Studentska 573, 53210 Pardubice (Czech Republic); Palarcik, Jiri [Institute of Environmental and Chemical Engineering, Faculty of Chemical Technology, University of Pardubice, Studentska 573, 53210 Pardubice (Czech Republic); Cadkova, Michaela [Department of Biological and Biochemical Sciences, Faculty of Chemical Technology, University of Pardubice, Studentska 573, 53210 Pardubice (Czech Republic); Department of Analytical Chemistry, Faculty of Chemical Technology, University of Pardubice, Studentska 573, 53210 Pardubice (Czech Republic); Belina, Petr [Department of Inorganic Technology, Faculty of Chemical Technology, University of Pardubice, Doubravice 41, 53210 Pardubice (Czech Republic); Vlcek, Milan [Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic, Heyrovskeho sq. 2, 16206 Prague (Czech Republic); Korecka, Lucie [Department of Biological and Biochemical Sciences, Faculty of Chemical Technology, University of Pardubice, Studentska 573, 53210 Pardubice (Czech Republic); Bilkova, Zuzana, E-mail: Zuzana.Bilkova@upce.cz [Department of Biological and Biochemical Sciences, Faculty of Chemical Technology, University of Pardubice, Studentska 573, 53210 Pardubice (Czech Republic)

    2014-11-01

    Iron oxide based particles functionalized by bioactive molecules have been utilized extensively in biotechnology and biomedicine. Despite their already proven advantages, instability under changing reaction conditions, non-specific sorption of biomolecules on the particles' surfaces, and iron oxide leakage from the naked particles can greatly limit their application. As confirmed many times, surface treatment with an appropriate stabilizer helps to minimize these disadvantages. In this work, we describe enhanced post-synthetic surface modification of superparamagnetic microparticles varying in materials and size using hyaluronic acid (HA) in various chain lengths. Scanning electron microscopy, atomic force microscopy, phase analysis light scattering and laser diffraction are the methods used for characterization of HA-coated particles. The zeta potential and thickness of HA-layer of HA-coated Dynabeads M270 Amine were − 50 mV and 85 nm, respectively, and of HA-coated p(GMA-MOEAA)-NH{sub 2} were − 38 mV and 140 nm, respectively. The electrochemical analysis confirmed the zero leakage of magnetic material and no reactivity of particles with hydrogen peroxide. The rate of non-specific sorption of bovine serum albumin was reduced up to 50% of the naked ones. The coating efficiency and suitability of biopolymer-based microparticles for magnetically active microfluidic devices were confirmed. - Highlights: • Post-synthetic surface modification of magnetic microparticles by hyaluronic acid • Hyaluronic acid — polymer of unique physicochemical and biological characteristics • Panel of particle characterization methods was introduced. • HA-coated microparticles gain characteristics suited for microfluidic bioanalysis.

  5. Stiffening of Human Mesenchymal Stem Cell Spheroid Microenvironments Induced by Incorporation of Gelatin Microparticles

    OpenAIRE

    Baraniak, Priya R.; Cooke, Marissa T; Saeed, Rabbia; Kinney, Melissa A.; Krista M Fridley; McDevitt, Todd C.

    2012-01-01

    Culturing multipotent adult mesenchymal stem cells as 3D aggregates augments their differentiation potential and paracrine activity. One caveat of stem cell spheroids, though, can be the limited diffusional transport barriers posed by the inherent 3D structure of the multicellular aggregates. In order to circumvent such limitations, polymeric microparticles have been incorporated into stem cell aggregates as a means to locally control the biochemical and physical properties of the 3D microenv...

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

    OpenAIRE

    Zhou, Yao; Wang, Yi; Lin, Qiao

    2010-01-01

    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 ...

  7. Mechanisms of burst release from pH-responsive polymeric microparticles.

    OpenAIRE

    Rizi, K.; Green, Rebecca J.; Khutoryanskaya, O; Donaldson, M.; Williams, Adrian C.

    2011-01-01

    Microencapsulation of drugs into preformed polymers is commonly achieved through solvent evaporation techniques or spray drying. We compared these encapsulation methods in terms of controlled drug release properties of the prepared microparticles and investigated the underlying mechanisms responsible for the “burst release” effect. Using two different pH-responsive polymers with a dissolution threshold of pH 6 (Eudragit L100 and AQOAT AS-MG), hydrocortisone, a model hydrophobic drug, was inco...

  8. Magnetic microparticles post-synthetically coated by hyaluronic acid as an enhanced carrier for microfluidic bioanalysis

    International Nuclear Information System (INIS)

    Iron oxide based particles functionalized by bioactive molecules have been utilized extensively in biotechnology and biomedicine. Despite their already proven advantages, instability under changing reaction conditions, non-specific sorption of biomolecules on the particles' surfaces, and iron oxide leakage from the naked particles can greatly limit their application. As confirmed many times, surface treatment with an appropriate stabilizer helps to minimize these disadvantages. In this work, we describe enhanced post-synthetic surface modification of superparamagnetic microparticles varying in materials and size using hyaluronic acid (HA) in various chain lengths. Scanning electron microscopy, atomic force microscopy, phase analysis light scattering and laser diffraction are the methods used for characterization of HA-coated particles. The zeta potential and thickness of HA-layer of HA-coated Dynabeads M270 Amine were − 50 mV and 85 nm, respectively, and of HA-coated p(GMA-MOEAA)-NH2 were − 38 mV and 140 nm, respectively. The electrochemical analysis confirmed the zero leakage of magnetic material and no reactivity of particles with hydrogen peroxide. The rate of non-specific sorption of bovine serum albumin was reduced up to 50% of the naked ones. The coating efficiency and suitability of biopolymer-based microparticles for magnetically active microfluidic devices were confirmed. - Highlights: • Post-synthetic surface modification of magnetic microparticles by hyaluronic acid • Hyaluronic acid — polymer of unique physicochemical and biological characteristics • Panel of particle characterization methods was introduced. • HA-coated microparticles gain characteristics suited for microfluidic bioanalysis

  9. Optoacoustic Detection of Microparticles in Liquids at Laser Fluences Below the Optical Breakdown Threshold

    OpenAIRE

    Alimpiev, S. S.; Simanovskii, Ya. O.; Egerev, S. V.; Pashin, A. E.

    1995-01-01

    An optoacoustic device consisting of a XeCl excimer laser and a measurement cell with an attached piezotransducer was used for detecting microparticles suspended in liquid probes. The potential of optoacoustic diagnostics of microinhomogeneous liquids was enhanced by applying informative parameters of optoacoustic response. Probes of distilled water and Dow Chemical latex suspension were used in experiments. It was shown that cavitation mechanism of optoacoustic conversion taking place at las...

  10. Functionalizable hydrogel microparticles of tunable size and stiffness for soft-tissue filler applications

    OpenAIRE

    Chan, Ka Man Carmen; Li, Randolph H.; Chapman, Joseph W.; Trac, Eric M.; Kobler, James B.; Zeitels, Steven M.; Langer, Robert; Karajanagi, Sandeep S

    2014-01-01

    Particle size, stiffness and surface functionality are important in determining the injection site, safety and efficacy of injectable soft-tissue fillers. Methods to produce soft injectable biomaterials with controlled particle characteristics are therefore desirable. Here we report a method based on suspension photopolymerization and semi-interpenetrating network (semi-IPN) to synthesize soft, functionalizable, spherical hydrogel microparticles (MP) of independently tunable size and stiffnes...

  11. A Microfluidic Chip Using Phenol Formaldehyde Resin for Uniform-Sized Polycaprolactone and Chitosan Microparticle Generation

    OpenAIRE

    Wan-Chen Hsieh; Keng-Shiang Huang; Szu-Yu Chen; Chih-Yu Wang; Alexandru Mihai Grumezescu; Yung-Sheng Lin; Chin-Tung Wu; Chih-Hui Yang

    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...

  12. Mathematical modeling of drug release from bioerodible microparticles: effect of gamma-irradiation.

    Science.gov (United States)

    Faisant, N; Siepmann, J; Richard, J; Benoit, J P

    2003-09-01

    Bioerodible polymers used in controlled drug delivery systems, such as poly(lactic-co-glycolic acid) (PLGA) undergo radiolytic degradation during gamma-irradiation. In spite of the considerable practical importance, yet only little knowledge is available on the consequences of this sterilization method on the resulting drug release patterns in a quantitative way. The major objectives of the present study were: (i) to monitor the effects of different gamma-irradiation doses on the physicochemical properties of drug-free and drug-loaded, PLGA-based microparticles; (ii) to analyze the obtained experimental results using adequate mathematical models; (iii) to get further insight into the occurring physical and chemical phenomena; and (iv) to relate the applied gamma-irradiation dose in a quantitative way to the resulting drug release rate. 5-Fluorouracil-loaded, PLGA-based microparticles were prepared with an oil-in-water solvent extraction method and exposed to gamma-irradiation doses ranging from 0 to 33 kGy. Size exclusion chromatography, differential scanning calorimetry, scanning electron microscopy, particle size analysis, determination of the actual drug loading and in vitro drug release kinetics were used to study the effects of the gamma-irradiation dose on the physicochemical properties of the microparticles. Two mathematical models-a simplified and a more comprehensive one-were used to analyze the experimental results. The simplified model considers drug diffusion based on Fick's second law for spherical geometry and a Higuchi-like pseudo-steady-state approach. The complex model combines Monte Carlo simulations (describing polymer erosion) with partial differential equations quantifying drug diffusion with time-, position- and direction-dependent diffusivities. Interestingly, exponential relationships between the gamma-irradiation dose and the initial drug diffusivity within the microparticles could be established. Based on this knowledge both models were

  13. Modification of Disodium Cromoglycate Passage Across Lung Epithelium In Vitro Via Incorporation into Polymeric Microparticles

    OpenAIRE

    Haghi, Mehra; Salama, Rania; Traini, Daniela; Bebawy, Mary; Young, Paul M.

    2011-01-01

    Two microparticle systems containing disodium cromoglycate (DSCG) alone or with polyvinyl alcohol (DSCG/PVA) were produced via spray drying and compared in terms of their physicochemical characteristics, aerosol performance and drug uptake across a pulmonary epithelial cell line (Calu-3), cultured under air interface conditions. The particle size distribution of DSCG and DSCG/PVA were similar, of spherical geometry, amorphous and suitable for inhalation purposes. Aerosolisation studies using ...

  14. Microwave-synthesized magnetic chitosan microparticles for the immobilization of yeast cells.

    Science.gov (United States)

    Safarik, Ivo; Pospiskova, Kristyna; Maderova, Zdenka; Baldikova, Eva; Horska, Katerina; Safarikova, Mirka

    2015-01-01

    An extremely simple procedure has been developed for the immobilization of Saccharomyces cerevisiae cells on magnetic chitosan microparticles. The magnetic carrier was prepared using an inexpensive, simple, rapid, one-pot process, based on the microwave irradiation of chitosan and ferrous sulphate at high pH. Immobilized yeast cells have been used for sucrose hydrolysis, hydrogen peroxide decomposition and the adsorption of selected dyes. PMID:24753015

  15. Quantification of tin and lead in binary alloys using voltammetry of immobilized microparticles

    OpenAIRE

    Arjmand Gholenji, Farzin; Adriaens, Annemie

    2011-01-01

    Voltammetry of immobilized microparticles (VMP) has been used in this work for the quantitative determination of tin and lead particles in their binary alloys. Carbon paste electrodes, which contained small amounts of tin and lead or their mixtures, were used as working electrodes and square wave voltammograms of each electrode were recorded. Quantification was performed using optimum experimental conditions, obtained by an experimental design technique. The calibration was made by measuring ...

  16. UNS S31603 Stainless Steel Tungsten Inert Gas Welds Made with Microparticle and Nanoparticle Oxides

    OpenAIRE

    Kuang-Hung Tseng; Po-Yu Lin

    2014-01-01

    The purpose of this study was to investigate the difference between tungsten inert gas (TIG) welding of austenitic stainless steel assisted by microparticle oxides and that assisted by nanoparticle oxides. SiO2 and Al2O3 were used to investigate the effects of the thermal stability and the particle size of the activated compounds on the surface appearance, geometric shape, angular distortion, delta ferrite content and Vickers hardness of the UNS S31603 stainless steel TIG weld. The results sh...

  17. Preparation and characterization of microparticles of piroxicam by spray drying and spray chilling methods

    OpenAIRE

    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 ...

  18. Preparation and in vivo toxicity study of solid lipid microparticles as carrier for pulmonary administration

    OpenAIRE

    Sanna, Vanna; Kirschvink, Nathalie; Gustin, Pascal; Gavini, Elisabeta; Roland, Isabelle; DELATTRE, Luc; Evrard, Brigitte

    2004-01-01

    The purpose of this research was to investigate the effects of processing conditions on the characteristics of solid lipid microparticles (SLM) with a potential application as carriers for pulmonary administration. Compritol (5.0% wt/wt) SLM dispersions were prepared by rotor-stator homogenization, at different surfactant concentrations and emulsification times. The SLM were characterized, in terms of morphology and size, after lyophilization and sterilization by autoclaving process. In vivo ...

  19. Covalent albumin microparticles as an adjuvant for production of mucosal vaccines against hepatitis B.

    Science.gov (United States)

    Sitta, Danielly L A; Guilherme, Marcos R; Garcia, Francielle P; Cellet, Thelma S P; Nakamura, Celso V; Muniz, Edvani C; Rubira, Adley F

    2013-09-01

    Covalently modified albumin (BSA) microparticles were developed for potential use as an adjuvant in mucosal vaccines against hepatitis B. To synthesize consistent protein particles, a covalent approach was proposed to modify BSA. Our strategy was to bond maleic anhydride (MA) molecules to BSA structure by nucleophilic reaction for further radical cross-linking/polymerization reaction with N',N'-dimethylacrylamide (DMAAm). The presence of poly(N',N'-dimethylacrylamide) in the protein network enables the microparticles to show well-defined, homogeneous forms. Cytotoxicity tests showed that the cytotoxic concentration for 50% of VERO cells (CC50) was 216.25 ± 5.30 μg mL(-1) in 72 h of incubation. The obtained CC50 value is relatively low for an incubation time of 72 h, suggesting an acceptable biocompatibility. Assay of total protein showed that the encapsulation efficiency of the microparticles with hepatitis B surface antigen (HBsAg) was 77.7 ± 0.2%. For the reference sample, which was incubated without HBsAg, the quantity of protein was below the limit of detection. PMID:23863080

  20. Optimization of paeonol-loaded microparticle formulation by response surface methodology.

    Science.gov (United States)

    Li, Sha-Sha; Li, Guo-Feng; Liu, Li; Li, Hui; Jiang, Xiao; Li, Xue-Ling; Liu, Zhi-Gang; Zuo, Ting; Weng, Li-Dong; Liu, Qiang

    2015-01-01

    In this study, a central composite rotatable design based on response surface methodology (RSM) was employed to design and formulate an appropriate paeonol microparticle formulation. Five levels of a three-factor, rotatable, central composite design were used to evaluate the critical formulation variables. The optimum conditions for preparing paeonol-loaded microparticles were predicted to be: polyvinyl alcohol (PVA) content (2.84%), the ratio of drug to polymer (6.88) and the stirring rate (1007.59 rpm). The optimized responses for production yield and loading efficiency were found to be 68.86% and 55.90%, respectively, and the particle size were 23.27 ± 0.76 µm and the sorting coefficient (σ) was 0.732. Furthermore, in vitro release study suggested that microparticle could be a suitable delivery system in treating skin disease for its sustained release of drug. In conclusion, RSM can be successfully used to optimize the effect of formulation variables. PMID:26225493

  1. Preconcentration and separation of ultra-trace beryllium using quinalizarine-modified magnetic microparticles

    Energy Technology Data Exchange (ETDEWEB)

    Ashtari, Parviz, E-mail: pashtari@aeoi.org.ir [State Key Laboratory of Chemo/Biosensing and Chemometrics, Biomedical Engineering Center, College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082 (China); NFCS, Nuclear Science and Technology Research Institute, PO Box 11365-8486, Tehran (Iran, Islamic Republic of); Wang Kemin; Yang Xiaohai [State Key Laboratory of Chemo/Biosensing and Chemometrics, Biomedical Engineering Center, College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082 (China); Ahmadi, Seyed Javad [NFCS, Nuclear Science and Technology Research Institute, PO Box 11365-8486, Tehran (Iran, Islamic Republic of)

    2009-07-30

    Magnetically-assisted chemical separation/preconcentration method for the analysis of beryllium from aqueous solutions was developed. According to this method several extractants were coated on certain magnetic microparticles to assist the extraction of beryllium from the aqueous solutions. The influence of different parameters (type and amount of extractant, pH, equilibrium time and ionic strength) was investigated. Also, the interfering effect of various cationic and anionic species on the percent recovery of beryllium was studied. The applied spectrophotometric method showed good linearity and precision at a given wavelength (605.0 nm). Among the extractants used, quinalizarine resulted in almost a full recovery of beryllium at pH 7.4, which was the optimum extraction pH. The equilibrium time of the extraction was 10.0 min. The quantitative re-extraction was carried out by 0.5 M nitric acid. Also, the stability of the extractant-coated magnetic microparticles was 4 cycles (extraction and re-extraction) and the used magnetic microparticles showed good selectivity for beryllium against other cations and anions. Finally, the developed method was applicable for the preconcentration and separation of beryllium from spring water, tap water and certified reference waters. The obtained detection limit was 30 ng L{sup -1}.

  2. Stiffening of Human Mesenchymal Stem Cell Spheroid Microenvironments Induced by Incorporation of Gelatin Microparticles

    Science.gov (United States)

    Baraniak, Priya R.; Cooke, Marissa T.; Saeed, Rabbia; Kinney, Melissa A.; Fridley, Krista M.; McDevitt, Todd C.

    2012-01-01

    Culturing multipotent adult mesenchymal stem cells as 3D aggregates augments their differentiation potential and paracrine activity. One caveat of stem cell spheroids, though, can be the limited diffusional transport barriers posed by the inherent 3D structure of the multicellular aggregates. In order to circumvent such limitations, polymeric microparticles have been incorporated into stem cell aggregates as a means to locally control the biochemical and physical properties of the 3D microenvironment. However, the introduction of biomaterials to the 3D stem cell microenvironment could alter the mechanical forces sensed by cells within aggregates, which in turn could impact various cell behaviors and overall spheroid mechanics. Therefore, the objective of this study was to determine the acute effects of biomaterial incorporation within mesenchymal stem cell spheroids on aggregate structure and mechanical properties. The results of this study demonstrate that although gelatin microparticle incorporation results in similar multi-cellular organization within human mesenchymal stem cell spheroids, the introduction of gelatin materials significantly impacts spheroid mechanical properties. The marked differences in spheroid mechanics induced by microparticle incorporation may hold major implications for in vitro directed differentiation strategies and offer a novel route to engineer the mechanical properties of tissue constructs ex vivo. PMID:22658155

  3. Dexamethasone-loaded poly(3-hydroxybutyrate-co-3-hydroxyvalerate) microparticles for controlled release

    International Nuclear Information System (INIS)

    Dexamethasone (DEX) has been widely used for the treatment of ulcerative colitis. The aim of the present study was to obtain DEX-loaded poly(3-hydroxybutyrate-co-3-hydroxyvalerate (PHBV) microparticles prepared by simple emulsion/solvent evaporation method. The drug loading and the encapsulation efficiency were determined by a previously validated UV method at 233 nm. Morphological, spectroscopical and dissolution analyses were also performed. The microparticles (formulation F no. 0, F no. 1 and F no. 2) were successfully obtained as off-white powders. A drug loading of 92.27 mg.g -1 and 218.54 mg.g-1 and an encapsulation efficiency of 93.96 % and 87.43 % were respectively observed for F no. 1 and F no. 2. Particles showed spherical and rough aspect by SEM. X-ray diffraction analysis demonstrated that the encapsulation reduced the drug crystallinity. FTIR spectra showed that no chemical bonding occurred between PHBV and DEX. Drug-loaded microparticles revealed controlled release profiles compared to pure DEX. (author)

  4. Formulation and optimization of rifampicin microparticles by Box-Behnken statistical design.

    Science.gov (United States)

    Maurya, D P; Sultana, Yasmin; Aqil, Mohd; Ali, A

    2012-01-01

    The objective of the present study was to optimize and evaluate in vitro gastroretentive performance of rifampicin microparticles. Formulations were optimized using design of experiments by employing a 4-factor, 3-level Box-Behnken statistical design. Independent variables studied were the ratio of polymers (Eudragit RSPO: ethyl cellulose), inert drug dispersing agent (talc), surfactant (sodium dodecyl sulfate) and stirring speed. The dependent variables were particle size and entrapment efficiency. Response surface plots were drawn, statistical validity of the polynomials was validated and the optimized formulation was characterized by Fourier Transform-InfraRed spectroscopy (FT-IR) and differential scanning calorimetry (DSC). Entrapment efficiency and particle size were determined. The designed microparticles have average particle size from 14.10 μm to 45.63 μm and entrapment efficiency from 38.14% to 94.81%. Optimized microparticles showed particle size and drug entrapment, 51.53 μm and 83.43%, respectively with sustained drug release behavior up to 12 h. In the present study, rifampicin microspheres were successfully prepared by a quasi-emulsion solvent diffusion technique for prolonged drug release. FT-IR and DSC studies did not reveal any significant drug interactions. The drug release was found to be controlled for more than 12 h by following zero order release pattern.

  5. Buserelin acetate microparticle dispersion effects drug release and plasma E(1) levels.

    Science.gov (United States)

    Usami, Makiko; Misawa, Kazumasa; Yagi, Naomi; Sekikawa, Hitoshi; Nabeshima, Toshitaka

    2007-07-18

    We investigated the effect of different dispersion methods on release behavior and efficacy onset following microparticle administration of buserelin acetate (BA) sustained-release injection. In this in vitro release study, the initial dispersion of BA increased with increased stirring speed (pmixer (2000 rpm) compared with the standard dispersion method (SDM) by hand. Without shaking, powder aggregation was observed, and BA release was lower than in either the SDM or VDM methods. In this study using 4-week-old Sprague-Dawley female rats, the initial plasma estrone (E(1)) concentrations were lower (p<0.05) in the VDM method than in the SDM method. Observations by optical microscope and scanning microscope showed no change in microparticle shape or distribution of size induced by SDM, VDM or the ultrasonication dispersion method. These results suggest that different dispersion methods do not change the shape and distribution of microparticle size, but clearly change the BA release rate and the transition in plasma E(1) concentrations that can affect drug efficacy. PMID:17398044

  6. Development and validation of HPLC method for quantitative analysis of triamcinolone in biodegradable microparticles

    Directory of Open Access Journals (Sweden)

    A. A. Silva-Júnior

    2009-01-01

    Full Text Available

    A simple, rapid, selective and specific high performance liquid chromatographic (HPLC method for quantitative analysis of the triamcinolone in polylactide-co-glycolide acid (PLGA microparticles was developed. The chromatographic parameters were reversed-phase C18 column, 250mm x 4.6mm, with particle size 5 m. The column oven was thermostated at 35 ºC ± 2 ºC. The mobile phase was methanol/water 45:55 (v/v and elution was isocratic at a flow-rate of 1mL.mL-1. The determinations were performed using a UV-Vis detector at 239 nm. The injected sample volume was 10 µL. The standard curve was linear (r2 > 0.999 in the concentration range 100-2500 ng.mL-1. The method showed adequate precision, with a relative standard deviation (RSD was smaller than 3%. The accuracy was analyzed by adding a standard drug and good recovery values were obtained for all drug concentrations used. The method showed specificity and selectivity with linearity in the working range and good precision and accuracy, making it very suitable for quantitation of triamcinolone in PLGA microparticles. Keywords: triamcinolone; HPLC analytical method; PLGA microparticles; analytical method validation.

  7. Pressure sensitive microparticle adhesion through biomimicry of the pollen-stigma interaction.

    Science.gov (United States)

    Lin, Haisheng; Qu, Zihao; Meredith, J Carson

    2016-03-21

    Many soft biomimetic synthetic adhesives, optimized to support macroscopic masses (∼kg), have been inspired by geckos, insects and other animals. Far less work has investigated bioinspired adhesion that is tuned to micro- and nano-scale sizes and forces. However, such adhesive forces are extremely important in the adhesion of micro- and nanoparticles to surfaces, relevant to a wide range of industrial and biological systems. Pollens, whose adhesion is critical to plant reproduction, are an evolutionary-optimized system for biomimicry to engineer tunable adhesion between particles and micro-patterned soft matter surfaces. In addition, the adhesion of pollen particles is relevant to topics as varied as pollinator ecology, transport of allergens, and atmospheric phenomena. We report the first observation of structurally-derived pressure-sensitive adhesion of a microparticle by using the sunflower pollen and stigma surfaces as a model. This strong, pressure-sensitive adhesion results from interlocking between the pollen's conical spines and the stigma's receptive papillae. Inspired by this behavior, we fabricated synthetic polymeric patterned surfaces that mimic the stigma surface's receptivity to pollen. These soft mimics allow the magnitude of the pressure-sensitive response to be tuned by adjusting the size and spacing of surface features. These results provide an important new insight for soft material adhesion based on bio-inspired principles, namely that ornamented microparticles and micro-patterned surfaces can be designed with complementarity that enable a tunable, pressure-sensitive adhesion on the microparticle size and length scale. PMID:26883733

  8. Microfluidic preparation of dual stimuli-responsive microparticles and light-directed clustering.

    Science.gov (United States)

    Lone, Saifullah; Kim, Sung Hoon; Nam, Seong Won; Park, Sungsu; Cheong, In Woo

    2010-12-01

    We present a simple fabrication of photo- and thermoresponsive microparticles with a narrow size distribution in the PDMS-based microfluidic device. The monodisperse water-in-oil (W/O) droplets of poly(N-isopropylacrylamide-co-spironaphthoxazine methacryloyl) (PNIPA-SPO) were formed at the T-junction channel of the device by adjusting the flow conditions of two immiscible solutions. Subsequently, the droplets were polymerized downstream of the channel under 365 nm UV irradiation in the presence of 2,2'-diethoxyacetophenone (DEAP, photoinitiator) and N,N'-methylenebisacrylamide (MBA, monomer and cross-linker). Being photosensitive, the polymerized microparticles progressively change their color when subjected to UV-vis irradiation. Above the LCST of the copolymer, the microparticles exhibited volume shrinkage accompanied by color deterioration. In addition, the UV light-driven clustering of the PNIPA-SPO copolymer was observed within the W/O droplet in the absence of photoinitiator, which contributed to variable microstructures from Janus to acorn-like and snowman-like morphologies. This work is the first attempt to unveil the photocontrolled asymmetric particle morphology by using the photoresponsive polymer. PMID:21033759

  9. In vitro characterization of insulin containing thiomeric microparticles as nasal drug delivery system.

    Science.gov (United States)

    Deutel, Britta; Laffleur, Flavia; Palmberger, Thomas; Saxer, Andreas; Thaler, Marlene; Bernkop-Schnürch, Andreas

    2016-01-01

    This study focused on a novel two step preparation method for the generation of insulin containing thiomer microparticles. The first step utilized the interpolymer complexation between poly(vinyl pyrrolidone) (PVP) and poly(acrylic acid) (PAA) or poly(acrylic acid)-cysteine (PAA-Cys), respectively, in the presence of insulin. Thereafter lyophilized coprecipitates were micronized via air jet mill. Particles were evaluated regarding size, morphology, insulin release and the effect on ciliary beat frequency of human nasal epithelial cells in vitro. Results displayed mean particle sizes of 2.6±1.6μm and 2.8±1.7μm for PAA/PVP/insulin and PAA-Cys/PVP/insulin microparticles, respectively, in a range where volitional impaction of particles on nasal epithelium takes place. Multi unit dosage forms showed in addition release for the incorporated insulin and nasal safety as to results of ciliary beat frequency studies (CBF). The introduced jet milled microparticles might in conclusion display a safe nasal insulin drug delivery system leading to improved absorption.

  10. Mucosal deformation from an impinging transonic gas jet and the ballistic impact of microparticles

    Science.gov (United States)

    Hardy, M. P.; Kendall, M. A. F.

    2005-10-01

    By means of a transonic gas jet, gene guns ballistically deliver microparticle formulations of drugs and vaccines to the outer layers of the skin or mucosal tissue to induce unique physiological responses for the treatment of a range of conditions. Reported high-speed imaging experiments show that the mucosa deforms significantly while subjected to an impinging gas jet from a biolistic device. In this paper, the effect of this tissue surface deformation on microparticle impact conditions is simulated with computational fluid dynamics (CFD) calculations. The microparticles are idealized as spheres of diameters 26.1, 39 and 99 µm and a density of 1050 kg m-3. Deforming surface calculations of particle impact conditions are compared directly with an immobile surface case. The relative velocity and obliquity of the deforming surface decrease the normal component of particle impact velocity by up to 30% at the outer edge of the impinging gas jet. This is qualitatively consistent with reported particle penetration profiles in the tissue. It is recommended that these effects be considered in biolistic studies requiring quantified particle impact conditions.

  11. Gentamicin-loaded poly(lactic-co-glycolic acid) microparticles for the prevention of maxillofacial and orthopedic implant infections.

    Science.gov (United States)

    Flores, Claudia; Degoutin, Stephanie; Chai, Feng; Raoul, Gwenael; Hornez, Jean-Chritophe; Martel, Bernard; Siepmann, Juergen; Ferri, Joel; Blanchemain, Nicolas

    2016-07-01

    Trauma and orthopedic surgery can cause infections as any open surgical procedures. Such complications occur in only1 to 5% of the cases, but the treatment is rather complicated due to bacterial biofilm formation and limited drug access to the site of infection upon systemic administration. An interesting strategy to overcome this type of complications is to prevent bacterial proliferation and biofilm formation via the local and controlled release of antibiotic drugs from the implant itself. Obviously, the incorporation of the drug into the implant should not affect the latter's biological and mechanical properties. In this context, we optimized the preparation process for gentamicin-loaded poly(lactic-co-glycolic acid) (PLGA) microparticles, which can be incorporated in the macropores of calcium phosphate-based bone substitutes. Microparticles were prepared using a double emulsion solvent extraction/evaporation technique. The processing parameters were optimized in order to provide an average microparticle size of about 60μm, allowing for incorporation inside the macropores (100μm) of the hydroxyapatite scaffold. Gentamicin-loaded PLGA microparticles showed a sustained release for 25-30days and a rapid antibacterial activity due to a burst effect, the extent of which was controlled by the initial loading of the microparticles. SEM pictures revealed a highly porous microparticle structure, which can help to reduce the micro environmental pH drop and autocatalytic effects. The biological evaluation showed the cytocompatibility and non-hemolytic property of the microparticles, and the antibacterial activity against Staphylococcus aureus under the given conditions.

  12. Injectable PEGylated fibrinogen cell-laden microparticles made with a continuous solvent- and oil-free preparation method.

    Science.gov (United States)

    Oliveira, Mariana B; Kossover, Olga; Mano, João F; Seliktar, Dror

    2015-02-01

    A new methodology is reported for the continuous, solvent- and oil-free production of photopolymerizable microparticles containing encapsulated human dermal fibroblasts. A precursor solution of cells in photoreactive poly(ethylene glycol) (PEG)-fibrinogen (PF) polymer was transported through a transparent injector exposed to light irradiation before being atomized in a jet-in-air nozzle. Shear rheometry data revealed the crosslinking kinetics of the PF/cell solution, which was then used to determine the amount of irradiation required to partially polymerize the mixture just prior to atomization. The partially polymerized drops of PF/cells fell into a gelation bath for further crosslinking until fully polymerized hydrogel microparticles were formed. As the drops of solution exited the air-in-jet nozzle, their viscosity was designed to be sufficiently high so as to prevent rapid mixing and/or dilution in the gelation bath, but without undergoing complete gelation in the nozzle. Several parameters of this system were varied to control the size and polydispersity of the microparticles, including the cell density, the flow rate and the air pressure in the nozzle. The system was capable of producing cell-laden microparticles with an average diameter of between 88.1 to 347.1 μm, and a dispersity of between 1.1 and 2.4, depending on the parameters chosen. Varying the precursor flow rate and/or cell density was beneficial in controlling the size and polydispersity of the microparticles; all microparticles exhibited very high cell viability, which was not affected by these parameters. In conclusion, this dropwise photopolymerization methodology for preparing cell-laden microparticles is an attractive alternative to existing techniques that use harsh solvents/oils and offer limited control over particle size and polydispersity. PMID:25462849

  13. A novel spray-dried nanoparticles-in-microparticles system for formulating scopolamine hydrobromide into orally disintegrating tablets

    Directory of Open Access Journals (Sweden)

    Li FQ

    2011-04-01

    Full Text Available Feng-Qian Li1, Cheng Yan2, Juan Bi1, Wei-Lin Lv3, Rui-Rui Ji3, Xu Chen1, Jia-Can Su3, Jin-Hong Hu31Department of Pharmaceutics, Shanghai Eighth People’s Hospital, Shanghai, People’s Republic of China; 2Department of Pharmacy, Bethune International Peace Hospital, Shijiazhuang, People’s Republic of China; 3Changhai Hospital, Second Military Medical University, Shanghai, People’s Republic of ChinaAbstract: Scopolamine hydrobromide (SH-loaded microparticles were prepared from a colloidal fluid containing ionotropic-gelated chitosan nanoparticles using a spray-drying method. The spray-dried microparticles were then formulated into orally disintegrating tablets (ODTs using a wet granulation tablet formation process. A drug entrapment efficiency of about 90% (w/w and loading capacity of 20% (w/w were achieved for the microparticles, which ranged from 2 µm to 8 µm in diameter. Results of disintegration tests showed that the formulated ODTs could be completely dissolved within 45 seconds. Drug dissolution profiles suggested that SH is released more slowly from tablets made using the microencapsulation process compared with tablets containing SH that is free or in the form of nanoparticles. The time it took for 90% of the drug to be released increased significantly from 3 minutes for conventional ODTs to 90 minutes for ODTs with crosslinked microparticles. Compared with ODTs made with noncrosslinked microparticles, it was thus possible to achieve an even lower drug release rate using tablets with appropriate chitosan crosslinking. Results obtained indicate that the development of new ODTs designed with crosslinked microparticles might be a rational way to overcome the unwanted taste of conventional ODTs and the side effects related to SH’s intrinsic characteristics.Keywords: scopolamine hydrobromide, chitosan, nanoparticles-in-microparticles system, spray-drying, orally disintegrating tablets

  14. The circulation physiology of agroecosystems

    Institute of Scientific and Technical Information of China (English)

    Cao Zhiping; Richard Dawson

    2007-01-01

    This paper represents an effort to enlarge the understanding of the biophysical foundation of agroecosystems by using an analogy with the circulation of the blood in the human body. The circulation function in the human body can be represented as arterial pressure. The factors affecting arterial pressure in the human body have direct counterparts in the cultivation-husbandry system. The relationship between circulation pressure and the factors affecting that pressure in the cultivation-husbandry system are similar to the relationship between the arterial pressure and factors affecting arterial pressure in the human body. Furthermore, circulation resistance in the cultivation-husbandry system can be shown to be analogous to the calculation of peripheral resistance in the human body by Poiseuille's formula.

  15. Atmospheric Circulation of Terrestrial Exoplanets

    OpenAIRE

    Showman, Adam P.; Wordsworth, Robin D.; Merlis, Timothy M.; Kaspi, Yohai

    2013-01-01

    The investigation of planets around other stars began with the study of gas giants, but is now extending to the discovery and characterization of super-Earths and terrestrial planets. Motivated by this observational tide, we survey the basic dynamical principles governing the atmospheric circulation of terrestrial exoplanets, and discuss the interaction of their circulation with the hydrological cycle and global-scale climate feedbacks. Terrestrial exoplanets occupy a wide range of physical a...

  16. Robust and Optimal Control of Magnetic Microparticles Inside Fluidic Channels with Time-varying Flow Rates

    Directory of Open Access Journals (Sweden)

    Islam S.M. Khalil

    2016-06-01

    Full Text Available Targeted therapy using magnetic microparticles and nanoparticles has the potential to mitigate the negative side-effects associated with conventional medical treatment. Major technological challenges still need to be addressed in order to translate these particles into in vivo applications. For example, magnetic particles need to be navigated controllably in vessels against flowing streams of body fluid. This paper describes the motion control of paramagnetic microparticles in the flowing streams of fluidic channels with time-varying flow rates (maximum flow is 35 ml.hr-1. This control is designed using a magnetic-based proportional-derivative (PD control system to compensate for the time-varying flow inside the channels (with width and depth of 2 mm and 1.5 mm, respectively. First, we achieve point-to-point motion control against and along flow rates of 4 ml.hr-1, 6 ml.hr-1, 17 ml.hr-1, and 35 ml.hr-1. The average speeds of single microparticle (with average diameter of 100 μm against flow rates of 6 ml.hr-1 and 30 ml.hr-1 are calculated to be 45 μm.s-1 and 15 μm.s-1, respectively. Second, we implement PD control with disturbance estimation and compensation. This control decreases the steady-state error by 50%, 70%, 73%, and 78% at flow rates of 4 ml.hr-1, 6 ml.hr-1, 17 ml.hr-1, and 35 ml.hr-1, respectively. Finally, we consider the problem of finding the optimal path (minimal kinetic energy between two points using calculus of variation, against the mentioned flow rates. Not only do we find that an optimal path between two collinear points with the direction of maximum flow (middle of the fluidic channel decreases the rise time of the microparticles, but we also decrease the input current that is supplied to the electromagnetic coils by minimizing the kinetic energy of the microparticles, compared to a PD control with disturbance compensation.

  17. Spherical gold nanoparticles and SiO{sub 2}/Au core/shell microparticles under intense femtosecond laser excitation: relaxation dynamics of gold nanoparticles and nanostructuring of borosilicate glass using SiO{sub 2}/Au microparticles

    Energy Technology Data Exchange (ETDEWEB)

    Shakhov, A M; Astaf' ev, A A; Gostev, F E; Shelaev, I V; Titov, A N; Nadtochenko, V A [N N Semenov Institute of Chemical Physics, Russian Academy of Sciences, Moscow (Russian Federation); Denisov, N N [Institute of Problems of Chemical Physics, Russian Academy of Sciences, Chernogolovka, Moscow Region (Russian Federation)

    2014-09-30

    This paper reports surface nanostructuring of borosilicate glass covered with a water layer and the production of ∼150 nm diameter pits using SiO{sub 2}/Au core/shell microparticles under excitation with 50 fs pulses (λ = 780 nm) using the optical scheme of an inverted microscope with a 100{sup ×}, NA = 1.4 objective. We compare the thresholds for hole formation in glass with the use of SiO{sub 2}/Au and uncoated SiO{sub 2} microparticles. The threshold is 0.7 J cm{sup -2} for SiO{sub 2}/Au and 2.9 J cm{sup -2} for SiO{sub 2} microparticles, which coincides with the threshold for nanostructuring by a focused femtosecond pulse without microparticles: 3 J cm{sup -2}. Femtosecond pump – probe spectroscopy has been used to study the relaxation dynamics of laser pulse energy absorbed in a Au nanoparticle and the dynamics of energy dissipation to the ambient medium. The threshold for cavitation bubble formation in water with SiO{sub 2}/Au has been determined to be 0.06 mJ cm{sup -2}, which is a factor of 30 lower than the bubble formation threshold in the case of uncoated SiO{sub 2} microparticles. (nanostructures)

  18. Flow Cytometric Quantification of Peripheral Blood Cell β-Adrenergic Receptor Density and Urinary Endothelial Cell-Derived Microparticles in Pulmonary Arterial Hypertension.

    Directory of Open Access Journals (Sweden)

    Jonathan A Rose

    Full Text Available Pulmonary arterial hypertension (PAH is a heterogeneous disease characterized by severe angiogenic remodeling of the pulmonary artery wall and right ventricular hypertrophy. Thus, there is an increasing need for novel biomarkers to dissect disease heterogeneity, and predict treatment response. Although β-adrenergic receptor (βAR dysfunction is well documented in left heart disease while endothelial cell-derived microparticles (Ec-MPs are established biomarkers of angiogenic remodeling, methods for easy large clinical cohort analysis of these biomarkers are currently absent. Here we describe flow cytometric methods for quantification of βAR density on circulating white blood cells (WBC and Ec-MPs in urine samples that can be used as potential biomarkers of right heart failure in PAH. Biotinylated β-blocker alprenolol was synthesized and validated as a βAR specific probe that was combined with immunophenotyping to quantify βAR density in circulating WBC subsets. Ec-MPs obtained from urine samples were stained for annexin-V and CD144, and analyzed by a micro flow cytometer. Flow cytometric detection of alprenolol showed that βAR density was decreased in most WBC subsets in PAH samples compared to healthy controls. Ec-MPs in urine was increased in PAH compared to controls. Furthermore, there was a direct correlation between Ec-MPs and Tricuspid annular plane systolic excursion (TAPSE in PAH patients. Therefore, flow cytometric quantification of peripheral blood cell βAR density and urinary Ec-MPs may be useful as potential biomarkers of right ventricular function in PAH.

  19. Improved intestinal absorption of a poorly water-soluble oral drug using mannitol microparticles containing a nanosolid drug dispersion.

    Science.gov (United States)

    Nishino, Yukiko; Kubota, Aya; Kanazawa, Takanori; Takashima, Yuuki; Ozeki, Tetsuya; Okada, Hiroaki

    2012-11-01

    A nozzle for a spray dryer that can prepare microparticles of water-soluble carriers containing various nanoparticles in a single step was previously developed in our laboratory. To enhance the solubility and intestinal absorption of poorly water-soluble drugs, we used probucol (PBL) as a poorly water-soluble drug, mannitol (MAN) as a water-soluble carrier for the microparticles, and EUDRAGIT (EUD) as a polymer vehicle for the solid dispersion. PBL-EUD-acetone-methanol and aqueous MAN solutions were simultaneously supplied through different liquid passages of the spray nozzle and dried together. PBL-EUD solid dispersion was nanoprecipitated in the MAN solution using an antisolvent mechanism and rapidly dried by surrounding it with MAN. PBL in the dispersion vehicle was amorphous and had higher physical stability according to powder X-ray diffraction and differential scanning calorimetry analysis. The bioavailability of PBL in PBL-EUD S-100-MAN microparticles after oral administration in rats was markedly higher (14- and 6.2-fold, respectively) than that of the original PBL powder and PBL-MAN microparticles. These results demonstrate that the composite microparticles containing a nanosized solid dispersion of a poorly water-soluble drug prepared using the spray nozzle developed by us should be useful to increase the solubility and bioavailability of drugs after oral administration. PMID:22864998

  20. Solvothermal synthesis of magnetic Fe3O4 microparticles via self-assembly of Fe3O4 nanoparticles

    Institute of Scientific and Technical Information of China (English)

    Wei Zhang; Fenglei Shen; Ruoyu Hong

    2011-01-01

    Ferromagnetic Fe3O4 nanoparticles were synthesized and then self-assembled into microparticles via a solvothermal method, using FeCI3.6H2O as the iron source, sodium oleate as the surfactant, and ethylene glycol as the reducing agent and solvent. The obtained Fe3O4 microparticles were characterized by X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy and vibrating sample magnetometer (VSM). The size and morphology of the particles were examined using transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The Fe3O4 microparticles of nearly monodisperse diameters, controllable in the range of 120-400 nm, consist of assemblies of Fe3O4nanoparticles with a diameter of 22 nm. The effects of reaction time, amount of surfactant and NaAc on the products were discussed. Interestingly, by using the pre-synthesized Fe3O4 microparticles as the growth substrates, spherical and smooth-looking Fe3O4 microparticles with average diameter of lμmwere obtained. A plausible formation process was discussed.

  1. Encapsulation of α-lipoic acid intochitosan and alginate/gelatin hydrogel microparticles and its in vitro antioxidant activity

    Directory of Open Access Journals (Sweden)

    Vidović Bojana B.

    2016-01-01

    Full Text Available Alpha-lipoic acidis an organosulphur compound well-known for its therapeutic potential and antioxidant properties. However, the effective use of α-lipoic acid depends on biological plasma half-life and its preserving stability, which could be improved by encapsulation. In this study, α-lipoic acid was incorporated into chitosan microparticles obtained by reverse emulsion crosslinking technique, as well as into microparticles of alginate/gelatin crosslinked with zinc ions. Encapsulation of α-lipoic acid in both cases was carried out by swelling of synthesized dried microparticles by their dipping in a solution of the active substance under strictly controlled conditions. Encapsulation efficiency of α-lipoic acid obtained in this study was up to 53.9 %. The structural interaction of α-lipoic acid with the carriers was revealed by Fourier transform infrared spectroscopy. In vitro released studies showed that controlled release of α-lipoic acid was achieved through its encapsulation into chitosan microparticles. The results of in vitro antioxidative activity assays of released α-lipoic acid indicated that antioxidant activity was preserved at a satisfactory level. These obtained results suggested that chitosan microparticles could be suitable for modeling the controlled release of α-lipoic acid. [Projekat Ministartsva nauke Republike Srbije, br. III 46010 i br. III46001

  2. Penetration of titanium dioxide microparticles in a sunscreen formulation into the horny layer and the follicular orifice.

    Science.gov (United States)

    Lademann, J; Weigmann, H; Rickmeyer, C; Barthelmes, H; Schaefer, H; Mueller, G; Sterry, W

    1999-01-01

    Coated titanium dioxide (TiO2) microparticles are commonly used as UV filter substances in commercial sunscreen products. The penetration of these microparticles into the horny layer and the orifice of the hair follicle was investigated. The distribution of the microparticles in the horny layer was analyzed using the method of tape stripping in combination with spectroscopic measurements. Deeper layers of the stratum corneum were devoid of TiO(2) even after repetitive application of sunscreen preparation when analyzing interfollicular areas. Only in the areas of the pilosebaceous orifices could microparticles be identified. The penetration of TiO(2) was investigated in histological skin sections. A biopsy was taken from a skin area from which the horny layer had been removed by tape stripping. In isolated areas, a penetration of coated TiO2 into the open part of the follicle was observed. The amount of TiO2 found in a given follicle was less than 1% of the applied total amount of sunscreens. A penetration of microparticles into viable skin tissue could not be detected. PMID:10461093

  3. Membrane Properties Involved in Calcium-Stimulated Microparticle Release from the Plasma Membranes of S49 Lymphoma Cells

    Directory of Open Access Journals (Sweden)

    Lauryl E. Campbell

    2014-01-01

    Full Text Available This study answered the question of whether biophysical mechanisms for microparticle shedding discovered in platelets and erythrocytes also apply to nucleated cells: cytoskeletal disruption, potassium efflux, transbilayer phospholipid migration, and membrane disordering. The calcium ionophore, ionomycin, disrupted the actin cytoskeleton of S49 lymphoma cells and produced rapid release of microparticles. This release was significantly inhibited by interventions that impaired calcium-activated potassium current. Microparticle release was also greatly reduced in a lymphocyte cell line deficient in the expression of scramblase, the enzyme responsible for calcium-stimulated dismantling of the normal phospholipid transbilayer asymmetry. Rescue of the scrambling function at high ionophore concentration also resulted in enhanced particle shedding. The effect of membrane physical properties was addressed by varying the experimental temperature (32–42°C. A significant positive trend in the rate of microparticle release as a function of temperature was observed. Fluorescence experiments with trimethylammonium diphenylhexatriene and Patman revealed significant decrease in the level of apparent membrane order along that temperature range. These results demonstrated that biophysical mechanisms involved in microparticle release from platelets and erythrocytes apply also to lymphocytes.

  4. Bone response and mechanical strength of rabbit femoral defects filled with injectable CaP cements containing TGF-beta 1 loaded gelatin microparticles.

    NARCIS (Netherlands)

    Link, D.P.; Dolder, J. van den; Beucken, J.J.J.P van den; Wolke, J.G.C.; Mikos, A.G.; Jansen, J.A.

    2008-01-01

    This study focused at the potential of transforming growth factor beta 1 (TGF-beta 1) loaded gelatin microparticles to enhance the bone response and mechanical strength of rabbit femoral defects filled with injectable calcium phosphate (CaP)/gelatin microparticle composites. Therefore, TGF-beta1 loa

  5. Modulating protein release profiles by incorporating hyaluronic acid into PLGA microparticles Via a spray dryer equipped with a 3-fluid nozzle

    DEFF Research Database (Denmark)

    Wan, Feng; Maltesen, Morten Jonas; Andersen, Sune Klint;

    2014-01-01

    PURPOSE: The purpose of this study was to modulate the release profiles of the model protein drug from spray dried poly(DL-lactic-co-glycolic acid) (PLGA) microparticles by incorporating hyaluronic acid (HA) in the formulation. METHODS: Bovine serum albumin (BSA)-loaded PLGA microparticles...

  6. Seasonal overturning circulation in the Red Sea: 2. Winter circulation

    KAUST Repository

    Yao, Fengchao

    2014-04-01

    The shallow winter overturning circulation in the Red Sea is studied using a 50 year high-resolution MITgcm (MIT general circulation model) simulation with realistic atmospheric forcing. The overturning circulation for a typical year, represented by 1980, and the climatological mean are analyzed using model output to delineate the three-dimensional structure and to investigate the underlying dynamical mechanisms. The horizontal model circulation in the winter of 1980 is dominated by energetic eddies. The climatological model mean results suggest that the surface inflow intensifies in a western boundary current in the southern Red Sea that switches to an eastern boundary current north of 24N. The overturning is accomplished through a cyclonic recirculation and a cross-basin overturning circulation in the northern Red Sea, with major sinking occurring along a narrow band of width about 20 km along the eastern boundary and weaker upwelling along the western boundary. The northward pressure gradient force, strong vertical mixing, and horizontal mixing near the boundary are the essential dynamical components in the model\\'s winter overturning circulation. The simulated water exchange is not hydraulically controlled in the Strait of Bab el Mandeb; instead, the exchange is limited by bottom and lateral boundary friction and, to a lesser extent, by interfacial friction due to the vertical viscosity at the interface between the inflow and the outflow. Key Points Sinking occurs in a narrow boundary layer along the eastern boundary Surface western boundary current switches into an eastern boundary current Water exchange in the Strait of Bab el Mandeb is not hydraulically controlled © 2014. American Geophysical Union. All Rights Reserved.

  7. The Invertibility, Explicit Determinants, and Inverses of Circulant and Left Circulant and g-Circulant Matrices Involving Any Continuous Fibonacci and Lucas Numbers

    Directory of Open Access Journals (Sweden)

    Zhaolin Jiang

    2014-01-01

    Full Text Available Circulant matrices play an important role in solving delay differential equations. In this paper, circulant type matrices including the circulant and left circulant and g-circulant matrices with any continuous Fibonacci and Lucas numbers are considered. Firstly, the invertibility of the circulant matrix is discussed and the explicit determinant and the inverse matrices by constructing the transformation matrices are presented. Furthermore, the invertibility of the left circulant and g-circulant matrices is also studied. We obtain the explicit determinants and the inverse matrices of the left circulant and g-circulant matrices by utilizing the relationship between left circulant, g-circulant matrices and circulant matrix, respectively.

  8. Toxicodynamics of rigid polystyrene microparticles on pulmonary gas exchange in mice: Implications for microemboli-based drug delivery systems

    Energy Technology Data Exchange (ETDEWEB)

    Kutscher, H.L. [Department of Pharmaceutics, Ernest Mario School of Pharmacy, Rutgers, The State University of New Jersey, Piscataway, NJ 08854 (United States); Gao, D.; Li, S. [Department of Pharmaceutics, Ernest Mario School of Pharmacy, Rutgers, The State University of New Jersey, Piscataway, NJ 08854 (United States); UMDNJ-Rutgers CounterACT Research Center of Excellence, Rutgers, The State University of New Jersey, Piscataway, NJ 08854 (United States); Massa, C.B.; Cervelli, J. [Department of Pharmacology and Toxicology, Ernest Mario School of Pharmacy, Rutgers, The State University of New Jersey, Piscataway, NJ 08854 (United States); Deshmukh, M. [Department of Pharmaceutics, Ernest Mario School of Pharmacy, Rutgers, The State University of New Jersey, Piscataway, NJ 08854 (United States); UMDNJ-Rutgers CounterACT Research Center of Excellence, Rutgers, The State University of New Jersey, Piscataway, NJ 08854 (United States); Joseph, L.B.; Laskin, D.L. [UMDNJ-Rutgers CounterACT Research Center of Excellence, Rutgers, The State University of New Jersey, Piscataway, NJ 08854 (United States); Department of Pharmacology and Toxicology, Ernest Mario School of Pharmacy, Rutgers, The State University of New Jersey, Piscataway, NJ 08854 (United States); Sinko, P.J., E-mail: sinko@rci.rutgers.edu [Department of Pharmaceutics, Ernest Mario School of Pharmacy, Rutgers, The State University of New Jersey, Piscataway, NJ 08854 (United States); UMDNJ-Rutgers CounterACT Research Center of Excellence, Rutgers, The State University of New Jersey, Piscataway, NJ 08854 (United States)

    2013-01-15

    The toxicodynamic relationship between the number and size of pulmonary microemboli resulting from uniformly sized, rigid polystyrene microparticles (MPs) administered intravenously and their potential effects on pulmonary gas exchange were investigated. CD-1 male mice (6–8 weeks) were intravenously administered 10, 25 and 45 μm diameter MPs. Oxygen hemoglobin saturation in the blood (SpO{sub 2}) was measured non-invasively using a pulse oximeter while varying inhaled oxygen concentration (F{sub I}O{sub 2}). The resulting data were fit to a physiologically based non-linear mathematical model that estimates 2 parameters: ventilation–perfusion ratio (V{sub A}/Q) and shunt (percentage of deoxygenated blood returning to systemic circulation). The number of MPs administered prior to a statistically significant reduction in normalized V{sub A}/Q was dependent on particle size. MP doses that resulted in a significant reduction in normalized V{sub A}/Q one day post-treatment were 4000, 40,000 and 550,000 MPs/g for 45, 25 and 10 μm MPs, respectively. The model estimated V{sub A}/Q and shunt returned to baseline levels 7 days post-treatment. Measuring SpO{sub 2} alone was not sufficient to observe changes in gas exchange; however, when combined with model-derived V{sub A}/Q and shunt early reversible toxicity from pulmonary microemboli was detected suggesting that the model and physical measurements are both required for assessing toxicity. Moreover, it appears that the MP load required to alter gas exchange in a mouse prior to lethality is significantly higher than the anticipated required MP dose for effective drug delivery. Overall, the current results indicate that the microemboli-based approach for targeted pulmonary drug delivery is potentially safe and should be further explored. -- Highlights: ► Murine pulmonary gas exchange after microembolization was non-invasively studied. ► A physiologically based model quantified impairment of pulmonary gas exchange.

  9. Toxicodynamics of rigid polystyrene microparticles on pulmonary gas exchange in mice: Implications for microemboli-based drug delivery systems

    International Nuclear Information System (INIS)

    The toxicodynamic relationship between the number and size of pulmonary microemboli resulting from uniformly sized, rigid polystyrene microparticles (MPs) administered intravenously and their potential effects on pulmonary gas exchange were investigated. CD-1 male mice (6–8 weeks) were intravenously administered 10, 25 and 45 μm diameter MPs. Oxygen hemoglobin saturation in the blood (SpO2) was measured non-invasively using a pulse oximeter while varying inhaled oxygen concentration (FIO2). The resulting data were fit to a physiologically based non-linear mathematical model that estimates 2 parameters: ventilation–perfusion ratio (VA/Q) and shunt (percentage of deoxygenated blood returning to systemic circulation). The number of MPs administered prior to a statistically significant reduction in normalized VA/Q was dependent on particle size. MP doses that resulted in a significant reduction in normalized VA/Q one day post-treatment were 4000, 40,000 and 550,000 MPs/g for 45, 25 and 10 μm MPs, respectively. The model estimated VA/Q and shunt returned to baseline levels 7 days post-treatment. Measuring SpO2 alone was not sufficient to observe changes in gas exchange; however, when combined with model-derived VA/Q and shunt early reversible toxicity from pulmonary microemboli was detected suggesting that the model and physical measurements are both required for assessing toxicity. Moreover, it appears that the MP load required to alter gas exchange in a mouse prior to lethality is significantly higher than the anticipated required MP dose for effective drug delivery. Overall, the current results indicate that the microemboli-based approach for targeted pulmonary drug delivery is potentially safe and should be further explored. -- Highlights: ► Murine pulmonary gas exchange after microembolization was non-invasively studied. ► A physiologically based model quantified impairment of pulmonary gas exchange. ► Number and size of microemboli determine severity

  10. Complex-shaped three-dimensional multi-compartmental microparticles generated by diffusional and Marangoni microflows in centrifugally discharged droplets

    Science.gov (United States)

    Hayakawa, Masayuki; Onoe, Hiroaki; Nagai, Ken H.; Takinoue, Masahiro

    2016-02-01

    We report a versatile method for the generation of complex-shaped three-dimensional multi-compartmental (3D-MC) microparticles. Complex-shaped microparticles have recently received much attention for potential application in self-assemblies, micromachines, and biomedical and environmental engineering. Here, we have developed a method based on 3D nonequilibrium-induced microflows (Marangoni and diffusional flows) of microdroplets that are discharged from the tip of a thin capillary in a simple centrifugal microfluidic device. The microparticle shapes can be tuned by the partial dissolution of specific compartments and by the deformation of the precursor microdroplets by manipulating the 3D microflows. We believe that this method will have wide applications in nano- and microscience and technologies.

  11. Shape-Encoded Chitosan-Polyacrylamide Hybrid Hydrogel Microparticles with Controlled Macroporous Structures via Replica Molding for Programmable Biomacromolecular Conjugation.

    Science.gov (United States)

    Kang, Eunae; Jung, Sukwon; Abel, John H; Pine, Allison; Yi, Hyunmin

    2016-05-31

    Polymeric hydrogel microparticle-based suspension arrays with shape-based encoding offer powerful alternatives to planar and bead-based arrays toward high throughput biosensing and medical diagnostics. We report a simple and robust micromolding technique for polyacrylamide- (PAAm-) based biopolymeric-synthetic hybrid microparticles with controlled 2D shapes containing a potent aminopolysaccharide chitosan as an efficient conjugation handle uniformly incorporated in PAAm matrix. A postfabrication conjugation approach utilizing amine-reactive chemistries on the chitosan shows stable incorporation and retained chemical reactivity of chitosan, readily tunable macroporous structures via simple addition of low content long-chain PEG porogens for improved conjugation capacity and kinetics, and one-pot biomacromolecular assembly via bioorthogonal click reactions with minimal nonspecific binding. We believe that the integrated fabrication-conjugation approach reported here could offer promising routes to programmable manufacture of hydrogel microparticle-based biomacromolecular conjugation and biofunctionalization platforms for a large range of applications. PMID:27191399

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

    Science.gov (United States)

    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.

  13. Catalytic properties of maltogenic α-amylase from Bacillus stearothermophilus immobilized onto poly(urethane urea) microparticles.

    Science.gov (United States)

    Straksys, Antanas; Kochane, Tatjana; Budriene, Saulute

    2016-11-15

    The immobilization of maltogenic α-amylase from Bacillus stearothermophilus (BsMa) onto novel porous poly(urethane urea) (PUU) microparticles synthesized from poly(vinyl alcohol) and isophorone diisocyanate was performed by covalent attachment to free isocyanate groups from PUU microparticles, or by physical adsorption of enzyme onto the surface of the carrier. The influence of structure, surface area and porosity of microparticles on the catalytic properties of immobilized BsMa was evaluated. The highest efficiency of immobilization of BsMa was found to be 72%. Optimal activity of immobilized BsMa was found to have increased by 10°C compared with the native enzyme. Influence of concentration of sodium chloride on activity of immobilized BsMa was evaluated. High storage and thermal stability and reusability for starch hydrolysis of immobilized enzyme were obtained. Immobilized BsMa has a great potential for biotechnology. PMID:27283635

  14. Poly(3-hydroxybutyrate) and Eudragit E microparticles: a release system to enhance the aqueous solubility of felodipine and simvastatin

    International Nuclear Information System (INIS)

    Poor water-soluble drugs are a problem for the development of oral solid dosage forms, since it has great potential for low bioavailability. Thus, release systems that promote the increase of aqueous solubility of these drugs are advantageous. This study aimed to evaluate the feasibility of incorporation of felodipine and simvastatin in polymeric microparticles, to improve the aqueous solubility of the drugs. Microparticles of poly(3-hydroxybutyrate) [PHB] and Eudragit E was prepared by emulsion - solvent evaporation technique and characterized as to morphology and encapsulation efficiency of the drugs. Particles with spherical shapes and high levels of drug encapsulated were obtained. There was a significant increase in aqueous solubility of felodipine and simvastatin after its incorporation into the polymeric microparticles. X-ray diffraction analysis showed the conversion of both drugs to amorphous form, which may have contributed to increased the solubility. (author)

  15. Production and characterization of alginate-starch-chitosan microparticles containing stigmasterol through the external ionic gelation technique

    Directory of Open Access Journals (Sweden)

    Gislene Mari Fujiwara

    2013-09-01

    Full Text Available Stigmasterol - a plant sterol with several pharmacological activities - is susceptible to oxidation when exposed to air, a process enhanced by heat and humidity. In this context, microencapsulation is a way of preventing oxidation, allowing stigmasterol to be incorporated into various pharmaceutical forms while increasing its absorption. Microparticles were obtained using a blend of polymers of sodium alginate, starch and chitosan as the coating material through a one-stage process using the external gelation technique. Resultant microparticles were spherical, averaging 1.4 mm in size. Encapsulation efficiency was 90.42% and method yield 94.87%. The amount of stigmasterol in the oil recovered from microparticles was 9.97 mg/g. This technique proved feasible for the microencapsulation of stigmasterol.

  16. [Circulating nucleic acids and infertility].

    Science.gov (United States)

    Scalici, E; Mullet, T; Ferrières Hoa, A; Gala, A; Loup, V; Anahory, T; Belloc, S; Hamamah, S

    2015-09-01

    Circulating nucleic acids (cell-free DNA and microRNAs) have for particularity to be easily detectable in the biological fluids of the body. Therefore, they constitute biomarkers of interest in female and male infertility care. Indeed, in female, they can be used to detect ovarian reserve disorders (polycystic ovary syndrome and low functional ovarian reserve) as well as to assess follicular microenvironment quality. Moreover, in men, their expression levels can vary in case of spermatogenesis abnormalities. Finally, circulating nucleic acids have also the ability to predict successfully the quality of in vitro embryo development. Their multiple contributions during assisted reproductive technology (ART) make of them biomarkers of interest, for the development of new diagnostic and/or prognostic tests, applied to our specialty. Circulating nucleic acids would so offer the possibility of personalized medical care for infertile couples in ART. PMID:26298813

  17. Atmospheric Circulation of Terrestrial Exoplanets

    CERN Document Server

    Showman, Adam P; Merlis, Timothy M; Kaspi, Yohai

    2013-01-01

    The investigation of planets around other stars began with the study of gas giants, but is now extending to the discovery and characterization of super-Earths and terrestrial planets. Motivated by this observational tide, we survey the basic dynamical principles governing the atmospheric circulation of terrestrial exoplanets, and discuss the interaction of their circulation with the hydrological cycle and global-scale climate feedbacks. Terrestrial exoplanets occupy a wide range of physical and dynamical conditions, only a small fraction of which have yet been explored in detail. Our approach is to lay out the fundamental dynamical principles governing the atmospheric circulation on terrestrial planets--broadly defined--and show how they can provide a foundation for understanding the atmospheric behavior of these worlds. We first survey basic atmospheric dynamics, including the role of geostrophy, baroclinic instabilities, and jets in the strongly rotating regime (the "extratropics") and the role of the Hadle...

  18. Proper Sizing of Circulation Pumps

    DEFF Research Database (Denmark)

    Tommerup, Henrik M.; Nørgaard, Jørgen

    2007-01-01

    , but the results can be applied to Europe in general. Despite the small sample of houses involved in the test, 15 houses, some rather safe conclusions can be drawn from the results, which showed that newly developed pumps with power consumption around 5-8 W, can perform the task of circulating the water...... as well as their pollution during operation. Policy measures are proposed of how to ensure that in the future only such energy saving pumps are installed. Furthermore, on the basis of the historic experiences with circulation pumps some con¬clusions are drawn on how to investigate, develop and market new...

  19. Highly conductive copper nano/microparticles ink via flash light sintering for printed electronics

    International Nuclear Information System (INIS)

    In this study, the size effect of copper particles on the flash light sintering of copper (Cu) ink was investigated using Cu nanoparticles (20–50 nm diameter) and microparticles (2 μm diameter). Also, the mixed Cu nano-/micro-inks were fabricated, and the synergetic effects between the Cu nano-ink and micro-ink on flash light sintering were assessed. The ratio of nanoparticles to microparticles in Cu ink and the several flash light irradiation conditions (irradiation energy density, pulse number, on-time, and off-time) were optimized to obtain high conductivity of Cu films. In order to precisely monitor the milliseconds-long flash light sintering process, in situ monitoring of electrical resistance and temperature changes of Cu films was conducted during the flash light irradiation using a real-time Wheatstone bridge electrical circuit, thermocouple-based circuit, and a high-rate data acquisition system. Also, several microscopic and spectroscopic characterization techniques such as scanning electron microscopy, x-ray diffraction, x-ray photoelectron spectroscopy, and Fourier transform infrared spectroscopy were used to characterize the flash light sintered Cu nano-/micro-films. In addition, the sheet resistance of Cu film was measured using a four-point probe method. This work revealed that the optimal ratio of nanoparticles to microparticles is 50:50 wt%, and the optimally fabricated and flash light sintered Cu nano-/micro-ink films have the lowest resistivity (80 μΩ cm) among nano-ink, micro-ink, or nano-micro mixed films. (papers)

  20. Formulation Development, Process Optimization, and In Vitro Characterization of Spray-Dried Lansoprazole Enteric Microparticles.

    Science.gov (United States)

    Vora, Chintan; Patadia, Riddhish; Mittal, Karan; Mashru, Rajashree

    2016-01-01

    This research focuses on the development of enteric microparticles of lansoprazole in a single step by employing the spray drying technique and studies the effects of variegated formulation/process variables on entrapment efficiency and in vitro gastric resistance. Preliminary trials were undertaken to optimize the type of Eudragit and its various levels. Further trials included the incorporation of plasticizer triethyl citrate and combinations of other polymers with Eudragit S 100. Finally, various process parameters were varied to investigate their effects on microparticle properties. The results revealed Eudragit S 100 as the paramount polymer giving the highest gastric resistance in comparison to Eudragit L 100-55 and L 100 due to its higher pH threshold and its polymeric backbone. Incorporation of plasticizer not only influenced entrapment efficiency, but diminished gastric resistance severely. On the contrary, polymeric combinations reduced entrapment efficiency for both sodium alginate and glyceryl behenate, but significantly influenced gastric resistance for only sodium alginate and not for glyceryl behenate. The optimized process parameters were comprised of an inlet temperature of 150°C, atomizing air pressure of 2 kg/cm(2), feed solution concentration of 6% w/w, feed solution spray rate of 3 ml/min, and aspirator volume of 90%. The SEM analysis revealed smooth and spherical shape morphologies. The DSC and PXRD study divulged the amorphous nature of the drug. Regarding stability, the product was found to be stable under 3 months of accelerated and long-term stability conditions as per ICH Q1A(R2) guidelines. Thus, the technique offers a simple means to generate polymeric enteric microparticles that are ready to formulate and can be directly filled into hard gelatin capsules. PMID:27222612

  1. Genotoxicity of nano/microparticles in in vitro micronuclei, in vivo comet and mutation assay systems

    Directory of Open Access Journals (Sweden)

    Fukumori Nobutaka

    2009-09-01

    Full Text Available Abstract Background Recently, manufactured nano/microparticles such as fullerenes (C60, carbon black (CB and ceramic fiber are being widely used because of their desirable properties in industrial, medical and cosmetic fields. However, there are few data on these particles in mammalian mutagenesis and carcinogenesis. To examine genotoxic effects by C60, CB and kaolin, an in vitro micronuclei (MN test was conducted with human lung cancer cell line, A549 cells. In addition, DNA damage and mutations were analyzed by in vivo assay systems using male C57BL/6J or gpt delta transgenic mice which were intratracheally instilled with single or multiple doses of 0.2 mg per animal of particles. Results In in vitro genotoxic analysis, increased MN frequencies were observed in A549 cells treated with C60, CB and kaolin in a dose-dependent manner. These three nano/microparticles also induced DNA damage in the lungs of C57BL/6J mice measured by comet assay. Moreover, single or multiple instillations of C60 and kaolin, increased either or both of gpt and Spi- mutant frequencies in the lungs of gpt delta transgenic mice. Mutation spectra analysis showed transversions were predominant, and more than 60% of the base substitutions occurred at G:C base pairs in the gpt genes. The G:C to C:G transversion was commonly increased by these particle instillations. Conclusion Manufactured nano/microparticles, CB, C60 and kaolin, were shown to be genotoxic in in vitro and in vivo assay systems.

  2. Endocytosis and intracellular processing of platelet microparticles by brain endothelial cells.

    Science.gov (United States)

    Faille, Dorothée; El-Assaad, Fatima; Mitchell, Andrew J; Alessi, Marie-Christine; Chimini, Giovanna; Fusai, Thierry; Grau, Georges E; Combes, Valéry

    2012-08-01

    Platelet-derived microparticles (PMP) bind and modify the phenotype of many cell types including endothelial cells. Recently, we showed that PMP were internalized by human brain endothelial cells (HBEC). Here we intend to better characterize the internalization mechanisms of PMP and their intracellular fate. Confocal microscopy analysis of PKH67-labelled PMP distribution in HBEC showed PMP in early endosome antigen 1 positive endosomes and in LysoTracker-labelled lysosomes, confirming a role for endocytosis in PMP internalization. No fusion of calcein-loaded PMP with HBEC membranes was observed. Quantification of PMP endocytosis using flow cytometry revealed that it was partially inhibited by trypsin digestion of PMP surface proteins and by extracellular Ca(2+) chelation by EDTA, suggesting a partial role for receptor-mediated endocytosis in PMP uptake. This endocytosis was independent of endothelial receptors such as intercellular adhesion molecule-1 and vascular cell adhesion molecule-1 and was not increased by tumour necrosis factor stimulation of HBEC. Platelet-derived microparticle internalization was dramatically increased in the presence of decomplemented serum, suggesting a role for PMP opsonin-dependent phagocytosis. Platelet-derived microparticle uptake was greatly diminished by treatment of HBEC with cytochalasin D, an inhibitor of microfilament formation required for both phagocytosis and macropinocytosis, with methyl-β-cyclodextrin that depletes membrane cholesterol needed for macropinocytosis and with amiloride that inhibits the Na(+)/H(+) exchanger involved in macropinocytosis. In conclusion, PMP are taken up by active endocytosis in HBEC, involving mechanisms consistent with both phagocytosis and macropinocytosis. These findings identify new processes by which PMP could modify endothelial cell phenotype and functions.

  3. Pigments and plastic in limnetic ecosystems: A qualitative and quantitative study on microparticles of different size classes.

    Science.gov (United States)

    Imhof, Hannes K; Laforsch, Christian; Wiesheu, Alexandra C; Schmid, Johannes; Anger, Philipp M; Niessner, Reinhard; Ivleva, Natalia P

    2016-07-01

    Recently, macroplastic (>5 mm) and especially microplastic (Lake Garda, Italy). Moreover, our qualitative and quantitative analyses revealed that the number of paint microparticles significantly increased below the size range of 50 μm due to their brittleness (the smallest detected paint particle had a size of 4 μm). Inductively coupled plasma mass spectrometry measurements showed that both colored particles found in nature as well as virgin particles contain a high variety of metals such as cadmium, lead and copper. These additives may elicit adverse effects in biota ingesting these microparticles, thus paints and associated compounds may act as formerly overlooked contaminants in freshwater ecosystems.

  4. Mucosal vaccination against diphtheria using starch microparticles as adjuvant for cross-reacting material (CRM197) of diphtheria toxin.

    Science.gov (United States)

    Rydell, Niclas; Sjöholm, Ingvar

    2005-04-15

    Mucosal vaccination has the advantage of eliciting a local mucosal immune response as well as a systemic response. In this investigation, polyacryl starch microparticles were conjugated to diphtheria toxin cross-reacting material (CRM197) as a mucosal adjuvant for oral or intranasal immunisation of mice. Various methods of stabilising CRM197 with formaldehyde were investigated. A good systemic and local mucosal immune response was attained with oral immunisation when CRM197 was treated with a relatively low formaldehyde concentration prior to conjugation to the microparticles. No immune response was seen after intranasal immunisation.

  5. Magnetically responsive microparticles for targeted drug and radionuclide delivery.

    Energy Technology Data Exchange (ETDEWEB)

    Kaminski, M. D.; Ghebremeskel, A. N.; Nunez, L.; Kasza, K. E.; Chang, F.; Chien, T.-H.; Fisher, P. F.; Eastman, J. A.; Rosengart, A. J.; McDonald, L.; Xie, Y.; Johns, L.; Pytel, P.; Hafeli, U. O.

    2004-02-16

    We are currently investigating the use of magnetic particles--polymeric-based spheres containing dispersed magnetic nanocrystalline phases--for the precise delivery of drugs via the human vasculature. According to this review, meticulously prepared magnetic drug targeting holds promise as a safe and effective method of delivering drugs to specific organ, tissue or cellular targets. We have critically examined the wide range of approaches in the design and implementation of magnetic-particle-based drug delivery systems to date, including magnetic particle preparation, drug encapsulation, biostability, biocompatibility, toxicity, magnetic field designs, and clinical trials. However, we strongly believe that there are several limitations with past developments that need to be addressed to enable significant strides in the field. First, particle size has to be carefully chosen. Micrometer-sized magnetic particles are better attracted over a distance than nanometer sized magnetic particles by a constant magnetic field gradient, and particle sizes up to 1 {micro}m show a much better accumulation with no apparent side effects in small animal models, since the smallest blood vessels have an inner diameter of 5-7 {micro}m. Nanometer-sized particles <70 nm will accumulate in organ fenestrations despite an effective surface stabilizer. To be suitable for future human applications, our experimental approach synthesizes the magnetic drug carrier according to specific predefined outcome metrics: monodisperse population in a size range of 100 nm to 1.0 {micro}m, non-toxic, with appropriate magnetic properties, and demonstrating successful in vitro and in vivo tests. Another important variable offering possible improvement is surface polarity, which is expected to prolong particle half-life in circulation and modify biodistribution and stability of drugs in the body. The molecules in the blood that are responsible for enhancing the uptake of particles by the reticuloendothelial

  6. Observing Electrokinetic Janus Particle-Channel Wall Interaction Using Microparticle Image Velocimetry.

    Science.gov (United States)

    Boymelgreen, Alicia; Yossifon, Gilad

    2015-08-01

    Three-dimensional/two-component microparticle image velocimetry is used to examine the hydrodynamic flow patterns around metallodielectric Janus particles 15 μm in diameter adjacent to insulating and conducting walls. Far from the walls, the observed flow patterns are in good qualitative agreement with previous experimental and analytical models. However, close to the conducting wall, strong electrohydrodynamic flows are observed at low frequencies, which result in fluid being injected toward the particle. The proximity of the metallic hemisphere to the conducting wall is also shown to produce a localized field gradient, which results in dielectrophoretic trapping of 300 nm polystyrene particles across a broad range of frequencies.

  7. Synthesis and evaluation of novel bioactive composite starch/bioactive glass microparticles

    OpenAIRE

    Silva, G. A.; Costa, F. J.; Coutinho, O. P.; Radin, S.; Ducheyne, P.; Reis, R. L.

    2004-01-01

    The aim of the development of composite materials is to combine the most desired properties of two or more materials. In this work, the biodegradable character, good controlled-release properties, and natural origin of starch-based biomaterials are combined with the bioactive and bone-bonding properties of bioactive glass (BG). Novel, bioactive composite starch-BG microparticles were synthesized starting from a blend of starch and polylactic acid (50%/50% wt) with BG 45S5 powder using a simpl...

  8. Dynamic testing and in vivo evaluation of dermally implantable luminescent microparticle glucose sensors

    Science.gov (United States)

    Long, Ruiqi; Collier, Bradley; Roberts, Jason; McShane, Michael

    2010-02-01

    We have been developing dermally-implantable microparticle glucose sensors to monitor interstitial glucose levels. For these sensors to be deployed in vivo, a matched opto-electronic system to interrogate implanted sensors has been designed and constructed. The aim of this study is to test the capability of the sensor system, including in vivo sensor performance, hardware efficiency and hardware optimization based on test results. This paper will report the results of dynamic in vitro tests of sensor performance and the results of preliminary experiments of implants in animal models.

  9. Mechanical evaluation of implanted calcium phosphate cement incorporated with PLGA microparticles

    OpenAIRE

    Link, Dennis P.; VAN DEN DOLDER, Juliette; Jurgens, J. F. M.; Wolke, Joop G.; Jansen, John A.

    2006-01-01

    In this study, the mechanical properties of an implanted calcium phosphate (CaP) cement incorporated with 20wt% poly (DL-lactic-coglycolic acid) (PLGA) microparticles were investigated in a rat cranial defect. After 2, 4 and 8 weeks of implantation, implants were evaluated mechanically (push-out test) and morphologically (Scanning Electron Microscopy (SEM) and histology). The results of the push-out test showed that after 2 weeks the shear strength of the implants was 0.4470.44MPa (a...

  10. Three-Dimensional Dielectrophoretic Microparticle Separator Fabricated by Ultraviolet-Assisted Direct-Write Assembly.

    Science.gov (United States)

    Dalir, Hamid; Farahani, Rouhollah D; Hernandez, Lewith; Aldebert, Clément; Lévesque, Martin; Therriault, Daniel

    2016-01-01

    The design and fabrication of complex microfluidic devices is a subject of broad biomedical and technological interest. In this paper, we demonstrate the fabrication of a three-dimensional (3D) dielectrophoretic microparticle separator involving ultraviolet (UV)-assisted direct-write assembly of a UV-curable polyurethane. This approach yields a series of 3D microcoil interdigitated electrodes with defined geometry promoting particle separation through dielectrophoresis. These vertical microcoils give rise to considerable improvements in separation relative to standard planar (2D) microelectrodes. We envisage that the complex 3D electrodes will provide an enabling platform for a wide array of fluidic- and electronic-based applications. PMID:27398520

  11. Increased plasma levels of microparticles expressing CD39 and CD133 in acute liver injury

    DEFF Research Database (Denmark)

    Schmelzle, Moritz; Splith, Katrin; Wiuff Andersen, Lars;

    2013-01-01

    BACKGROUND: We have previously demonstrated that CD133 and CD39 are expressed by hematopoietic stem cells (HSC), which are mobilized after liver injury and target sites of injury, limit vascular inflammation, and boost hepatic regeneration. Plasma microparticles (MP) expressing CD39 can block...... endothelial activation. Here, we tested whether CD133 MP might be shed in a CD39-dependent manner in a model of liver injury and could potentially serve as biomarkers of liver failure in the clinic. METHODS: Wild-type and Cd39-null mice were subjected to acetaminophen-induced liver injury. Mice were...

  12. XPS and Raman study of zinc containing silica microparticles loaded with insulin

    Energy Technology Data Exchange (ETDEWEB)

    Vanea, E.; Simon, V., E-mail: viorica.simon@phys.ubbcluj.ro

    2013-09-01

    Zinc–silica microparticles obtained by sol–gel method solely or by combining sol–gel chemistry with freeze-drying and spray-drying procedures were explored as potential insulin drug delivery carriers for their improved loading efficiency. Zinc containing silica hosts of different specific surface area and mean pore volume loaded with insulin under similar conditions were investigated by X-ray photoelectron spectroscopy (XPS) and confocal micro-Raman spectroscopy in order to assess the insulin adherence to these matrices and the biologically active state of the insulin after embedding.

  13. Using DNA to program the self-assembly of colloidal nanoparticles and microparticles

    Science.gov (United States)

    Rogers, W. Benjamin; Shih, William M.; Manoharan, Vinothan N.

    2016-03-01

    DNA is not just the stuff of our genetic code; it is also a means to design self-assembling materials. Grafting DNA onto nano- and microparticles can, in principle, ‘program’ them with information that tells them exactly how to self-assemble. Although fully programmable assembly has not yet been realized, the groundwork has been laid: with an understanding of how specific interparticle attractions arise from DNA hybridization, we can now make systems that reliably assemble in and out of equilibrium. We discuss these advances, and the design rules that will allow us to control — and ultimately program — the assembly of new materials.

  14. Transient ischemic attack induced by melted solid lipid microparticles protects rat brains from permanent focal ischemia.

    Science.gov (United States)

    Tsai, M-J; Kuo, Y-M; Tsai, Y-H

    2014-09-01

    This study aims to develop a transient ischemic attack (TIA) model in conscious animals and uses this model to investigate the effect of TIA on subsequent permanent ischemia. TIA was induced by injecting designed temperature-sensitive melted solid lipid microparticles with a melting point around body temperature into male Wistar rats via arterial cannulation. Neurologic deficit was monitored immediately after the injection without anesthesia. According to the clinical definition of TIA, rats were divided into neurologic symptom durations ischemic stroke was induced 3d after the induction of TIA by injecting a different kind of embolic particle manufactured by blending chitin and PLGA. The ischemic stroke.

  15. A low-cost ultrasonic spray dryer to produce spherical microparticles from polymeric matrices

    Directory of Open Access Journals (Sweden)

    Priscilla Paiva Luz

    2007-01-01

    Full Text Available The spray-drying technique has been widely used for drying heat-sensitive foods, pharmaceuticals, and other substances, because it leads to rapid solvent evaporation from droplets. This method involves the transformation of a feed from a fluid state into a dried particulate, by spraying the feed into a hot medium. Despite being most often considered a dehydration process, spray drying can also be used as an encapsulation method. Therefore, this work proposes the use of a simple and low-cost ultrasonic spray dryer system to produce spherical microparticles. This equipment was successfully applied to the preparation of dextrin microspheres on a laboratory scale and for academic purposes.

  16. Invert sugar formation with Saccharomyces cerevisiae cells encapsulated in magnetically responsive alginate microparticles

    Science.gov (United States)

    Safarik, Ivo; Sabatkova, Zdenka; Safarikova, Mirka

    2009-05-01

    Invert sugar (an equimolar mixture of glucose and fructose prepared by sucrose hydrolysis) is a very important food component. We have prepared magnetically responsive alginate microbeads containing entrapped Saccharomyces cerevisiae cells and magnetite microparticles which can be easily separated in an appropriate magnetic separator. The microbeads (typical diameter between 50 and 100 μm) were prepared using the water-in-oil emulsification process. The prepared microbeads containing yeast cells with invertase activity enabled efficient sucrose conversion. The biocatalyst was quite stable; the same catalytic activity was observed after one month storage at 4 °C and the microbeads could be used at least six times.

  17. Invert sugar formation with Saccharomyces cerevisiae cells encapsulated in magnetically responsive alginate microparticles

    Energy Technology Data Exchange (ETDEWEB)

    Safarik, Ivo [Department of Biomagnetic Techniques, Institute of Systems Biology and Ecology, Academy of Sciences, Na Sadkach 7, 370 05 Ceske Budejovice (Czech Republic); Department of Medical Biology, Faculty of Science, University of South Bohemia, Branisovska 31, 370 05 Ceske Budejovice (Czech Republic)], E-mail: ivosaf@yahoo.com; Sabatkova, Zdenka; Safarikova, Mirka [Department of Biomagnetic Techniques, Institute of Systems Biology and Ecology, Academy of Sciences, Na Sadkach 7, 370 05 Ceske Budejovice (Czech Republic)

    2009-05-15

    Invert sugar (an equimolar mixture of glucose and fructose prepared by sucrose hydrolysis) is a very important food component. We have prepared magnetically responsive alginate microbeads containing entrapped Saccharomyces cerevisiae cells and magnetite microparticles which can be easily separated in an appropriate magnetic separator. The microbeads (typical diameter between 50 and 100 {mu}m) were prepared using the water-in-oil emulsification process. The prepared microbeads containing yeast cells with invertase activity enabled efficient sucrose conversion. The biocatalyst was quite stable; the same catalytic activity was observed after one month storage at 4 deg. C and the microbeads could be used at least six times.

  18. Conservation of Circulation in Magnetohydrodynamics

    CERN Document Server

    Bekenstein, J D; Bekenstein, Jacob D.; Oron, Asaf

    2000-01-01

    We demonstrate, both at the Newtonian and (general) relativistic levels, theexistence of a generalization of Kelvin's circulation theorem (for pure fluids)which is applicable to perfect magnetohydrodynamics. The argument is based onthe least action principle for magnetohydrodynamic flow. Examples of the newconservation law are furnished. The new theorem should be helpful inidentifying new kinds of vortex phenomena distinct from magnetic ropes or fluidvortices.

  19. Neural Control of the Circulation

    Science.gov (United States)

    Thomas, Gail D.

    2011-01-01

    The purpose of this brief review is to highlight key concepts about the neural control of the circulation that graduate and medical students should be expected to incorporate into their general knowledge of human physiology. The focus is largely on the sympathetic nerves, which have a dominant role in cardiovascular control due to their effects to…

  20. VanderLaan Circulant Type Matrices

    Directory of Open Access Journals (Sweden)

    Hongyan Pan

    2015-01-01

    Full Text Available Circulant matrices have become a satisfactory tools in control methods for modern complex systems. In the paper, VanderLaan circulant type matrices are presented, which include VanderLaan circulant, left circulant, and g-circulant matrices. The nonsingularity of these special matrices is discussed by the surprising properties of VanderLaan numbers. The exact determinants of VanderLaan circulant type matrices are given by structuring transformation matrices, determinants of well-known tridiagonal matrices, and tridiagonal-like matrices. The explicit inverse matrices of these special matrices are obtained by structuring transformation matrices, inverses of known tridiagonal matrices, and quasi-tridiagonal matrices. Three kinds of norms and lower bound for the spread of VanderLaan circulant and left circulant matrix are given separately. And we gain the spectral norm of VanderLaan g-circulant matrix.

  1. Hydrothermal synthesis of cubic {alpha}-Fe{sub 2}O{sub 3} microparticles using glycine: Surface characterization, reaction mechanism and electrochemical activity

    Energy Technology Data Exchange (ETDEWEB)

    Yin Chunyang, E-mail: c.yin@murdoch.edu.au [School of Chemical and Mathematical Sciences, Murdoch University, Murdoch, 6150 WA (Australia); Minakshi, Manickam; Ralph, David E. [School of Chemical and Mathematical Sciences, Murdoch University, Murdoch, 6150 WA (Australia); Jiang Zhongtao [School of Engineering and Energy, Murdoch University, Murdoch, 6150 WA (Australia); Xie Zonghan; Guo Hua [School of Engineering, Edith Cowan University, Joondalup, WA, 6027 (Australia)

    2011-10-13

    Graphical abstract: Highlights: > We synthesize cubic {alpha}-Fe{sub 2}O{sub 3} (hematite) microparticles. > Their morphological, mineralogical and surface properties are determined. > Reaction mechanism based on thermodynamics and ionic equilibrium concepts are described. > Microparticles have charge capacity of 160 mAh/g and good columbic efficiency of 94%. - Abstract: Cubic {alpha}-Fe{sub 2}O{sub 3} (hematite) microparticles (side lengths = 0.3-1.3 {mu}m) have been synthesized using glycine and ferric chloride via a simple one-step hydrothermal reaction. Their morphological, mineralogical and surface properties have been determined using scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray diffractometry (XRD) and X-ray photoelectron spectroscopy (XPS). XRD analysis indicated that the synthesized {alpha}-Fe{sub 2}O{sub 3} microparticles were minerallogically pure. An increase in hydrothermal reaction duration from 10 to 24 h increased the atomic percentages of {alpha}-Fe{sub 2}O{sub 3} on the surface of the microparticles by almost 8%. The mechanism concerning reactions of species to produce this microparticles precipitate was elucidated based on thermodynamics and ionic equilibrium aspects. In the electrochemical analysis, the synthesized {alpha}-Fe{sub 2}O{sub 3} microparticles (as cathode material) exhibit an approximate charge capacity of 160 mAh/g and excellent coulombic efficiency of 94%.

  2. Monolayers of Poly(styrene/α-tert-butoxy-ω-vinylbenzyl-polyglycidol) Microparticles Formed by Controlled Self-Assembly with Potential Application as Protein-Repelling Substrates.

    Science.gov (United States)

    Wasilewska, Monika; Adamczyk, Zbigniew; Basinska, Teresa; Gosecka, Monika; Lupa, Dawid

    2016-09-20

    The kinetics of the self-assembly of poly(styrene/α-tert-butoxy-ω-vinylbenzyl-polyglycidol) microparticles on poly(allylamine hydrochloride)-derivatized silicon/silica substrate was determined by direct AFM imaging and streaming potential (SP) measurements. The kinetic runs acquired under diffusion-controlled transport were quantitatively interpreted in terms of the extended random sequential adsorption (RSA) model. This allowed confirmation of a core/shell morphology of the microparticles. The polyglycidol-rich shell of thickness equal to 25 nm exhibited a fuzzy structure that enabled penetration of particles into each other resulting in high coverage inaccessible for ordinary microparticles. The SP measurements interpreted by using the 3D electrokinetic model confirmed this microparticle structure. Additionally, the acid-base characteristics of the microparticle monolayers were determined for a broad pH range. By using the streaming potential measurements, human serum albumin (HSA) adsorption on the microparticle monolayers was investigated under in situ conditions. It was confirmed that the protein adsorption was considerably lower than for the reference case of bare silicon/silica substrate under the same physicochemical conditions. This effect was attributed to the presence of the shell diminishing the protein/microparticle physical interactions.

  3. Monolayers of Poly(styrene/α-tert-butoxy-ω-vinylbenzyl-polyglycidol) Microparticles Formed by Controlled Self-Assembly with Potential Application as Protein-Repelling Substrates.

    Science.gov (United States)

    Wasilewska, Monika; Adamczyk, Zbigniew; Basinska, Teresa; Gosecka, Monika; Lupa, Dawid

    2016-09-20

    The kinetics of the self-assembly of poly(styrene/α-tert-butoxy-ω-vinylbenzyl-polyglycidol) microparticles on poly(allylamine hydrochloride)-derivatized silicon/silica substrate was determined by direct AFM imaging and streaming potential (SP) measurements. The kinetic runs acquired under diffusion-controlled transport were quantitatively interpreted in terms of the extended random sequential adsorption (RSA) model. This allowed confirmation of a core/shell morphology of the microparticles. The polyglycidol-rich shell of thickness equal to 25 nm exhibited a fuzzy structure that enabled penetration of particles into each other resulting in high coverage inaccessible for ordinary microparticles. The SP measurements interpreted by using the 3D electrokinetic model confirmed this microparticle structure. Additionally, the acid-base characteristics of the microparticle monolayers were determined for a broad pH range. By using the streaming potential measurements, human serum albumin (HSA) adsorption on the microparticle monolayers was investigated under in situ conditions. It was confirmed that the protein adsorption was considerably lower than for the reference case of bare silicon/silica substrate under the same physicochemical conditions. This effect was attributed to the presence of the shell diminishing the protein/microparticle physical interactions. PMID:27552337

  4. Biodegradable Poly(D,L-Lactide/Lipid Blend Microparticles Prepared by Oil-in-Water Emulsion Method for Controlled Release Drug Delivery

    Directory of Open Access Journals (Sweden)

    Yaowalak Srisuwan

    2014-03-01

    Full Text Available The effects of blend ratio and drug loading content of poly(D,L-lactide (PDLL/stearic acid blends on microparticle characteristics and drug release behaviors were evaluated. The blend microparticles were prepared by an oil-in-water emulsion solvent evaporation method for drug delivery of a poorly water-soluble model drug, indomethacin. The microparticles were characterized using a combination of scanning electron microscopy (SEM, light scattering particle size analysis, differential scanning calorimetry (DSC and UV-vis spectrophotometry. The blend microparticles with a PDLL/stearic acid blend ratio in the range 100/0-95/5 (w/w exhibited a spherical shape with a smooth surface. Blend microparticles with a similar size (167-177 µm and drug loading efficiency (60-67% were obtained. The drug loading content did not affect the characteristics of the blend microparticles. An in vitro drug release test demonstrated that the level of drug release decreased as the stearic acid blend ratio increased and the drug loading content decreased. The overall results indicated that it was possible to use PDLL/stearic acid blend microparticles as a controlled release drug delivery system.

  5. Spray-dried Eudragit® L100 microparticles containing ferulic acid: Formulation, in vitro cytoprotection and in vivo anti-platelet effect.

    Science.gov (United States)

    Nadal, Jessica Mendes; Gomes, Mona Lisa Simionatto; Borsato, Débora Maria; Almeida, Martinha Antunes; Barboza, Fernanda Malaquias; Zawadzki, Sônia Faria; Kanunfre, Carla Cristine; Farago, Paulo Vitor; Zanin, Sandra Maria Warumby

    2016-07-01

    This paper aimed to obtain new spray-dried microparticles containing ferulic acid (FA) prepared by using a methacrylic polymer (Eudragit® L100). Microparticles were intended for oral use in order to provide a controlled release, and improved in vitro and in vivo biological effects. FA-loaded Eudragit® L100 microparticles were obtained by spray-drying. Physicochemical properties, in vitro cell-based effects, and in vivo platelet aggregation were investigated. FA-loaded Eudragit® L100 microparticles were successfully prepared by spray-drying. Formulations showed suitable encapsulation efficiency, i.e. close to 100%. Microparticles were of spherical and almost-spherical shape with a smooth surface and a mean diameter between 2 and 3μm. Fourier-transformed infrared spectra demonstrated no chemical bond between FA and polymer. X-ray diffraction and differential scanning calorimetry analyses indicated that microencapsulation led to drug amorphization. FA-loaded microparticles showed a slower dissolution rate than pure drug. The chosen formulation demonstrated higher in vitro cytoprotection, anti-inflammatory and immunomodulatory potential and also improved in vivo anti-platelet effect. These results support an experimental basis for the use of FA spray-dried microparticles as a feasible oral drug delivery carrier for the controlled release of FA and improved cytoprotective and anti-platelet effects. PMID:27127059

  6. Improved physical stability and injectability of non-aqueous in situ PLGA microparticle forming emulsions.

    Science.gov (United States)

    Voigt, M; Koerber, M; Bodmeier, R

    2012-09-15

    The goal of this study was to obtain physically stable non-aqueous in situ forming microparticle (ISM) emulsions capable of forming biodegradable microparticles upon injection. ISM emulsions consist of a biocompatible organic PLGA solution dispersed in a continuous oil phase prepared in a two-syringe/connector system prior to administration. A variety of parenteral approved excipients were tested for a stability-enhancing effect and possible stabilization mechanisms evaluated. Glycerol monostearate (GMS) showed superior stabilizing potential prolonging the emulsion stability from a few minutes to more than 12h. Flow behavior analysis, differential scanning calorimetry, polarized light- and Cryo-electron microscopy revealed, that the stabilization was caused by an immediate, more than 5-fold viscosity increase in the continuous phase after emulsification and by a stabilized interface through a liquid crystalline GMS layer around the polymer solution droplets. Despite the viscosity increase the injectability of the stabilized ISM emulsion was improved by about 30% compared to the corresponding highly viscous PLGA solution (in situ implant) due to a pronounced shear thinning of the GMS containing oil phase. The injectability improvement allows a faster administration or enables the use of thinner needles and hence reduced patient discomfort. PMID:22677417

  7. Synthesis of Flexible Aerogel Composites Reinforced with Electrospun Nanofibers and Microparticles for Thermal Insulation

    Directory of Open Access Journals (Sweden)

    Huijun Wu

    2013-01-01

    Full Text Available Flexible silica aerogel composites in intact monolith of 12 cm were successfully fabricated by reinforcing SiO2 aerogel with electrospun polyvinylidene fluoride (PVDF webs via electrospinning and sol-gel processing. Three electrospun PVDF webs with different microstructures (e.g., nanofibers, microparticles, and combined nanofibers and microparticles were fabricated by regulating electrospinning parameters. The as-electrospun PVDF webs with various microstructures were impregnated into the silica sol to synthesize the PVDF/SiO2 composites followed by solvent exchange, surface modification, and drying at ambient atmosphere. The morphologies of the PVDF/SiO2 aerogel composites were characterized and the thermal and mechanical properties were measured. The effects of electrospun PVDF on the thermal and mechanical properties of the aerogel composites were evaluated. The aerogel composites reinforced with electrospun PVDF nanofibers showed intact monolith, improved strength, and perfect flexibility and hydrophobicity. Moreover, the aerogel composites reinforced with the electrospun PVDF nanofibers had the lowest thermal conductivity (0.028 W·m−1·K−1. It indicates that the electrospun PVDF nanofibers could greatly improve the mechanical strength and flexibility of the SiO2 aerogels while maintaining a lower thermal conductivity, which provides increasing potential for thermal insulation applications.

  8. Controlled Inhibition of the Mesenchymal Stromal Cell Pro-inflammatory Secretome via Microparticle Engineering

    Directory of Open Access Journals (Sweden)

    Sudhir H. Ranganath

    2016-06-01

    Full Text Available Mesenchymal stromal cells (MSCs are promising therapeutic candidates given their potent immunomodulatory and anti-inflammatory secretome. However, controlling the MSC secretome post-transplantation is considered a major challenge that hinders their clinical efficacy. To address this, we used a microparticle-based engineering approach to non-genetically modulate pro-inflammatory pathways in human MSCs (hMSCs under simulated inflammatory conditions. Here we show that microparticles loaded with TPCA-1, a small-molecule NF-κB inhibitor, when delivered to hMSCs can attenuate secretion of pro-inflammatory factors for at least 6 days in vitro. Conditioned medium (CM derived from TPCA-1-loaded hMSCs also showed reduced ability to attract human monocytes and prevented differentiation of human cardiac fibroblasts to myofibroblasts, compared with CM from untreated or TPCA-1-preconditioned hMSCs. Thus, we provide a broadly applicable bioengineering solution to facilitate intracellular sustained release of agents that modulate signaling. We propose that this approach could be harnessed to improve control over MSC secretome post-transplantation, especially to prevent adverse remodeling post-myocardial infarction.

  9. Preparation and Characterization of Potentially Antimicrobial Polymer Films Containing Starch Nano- and Microparticles

    Directory of Open Access Journals (Sweden)

    Paulius Pavelas DANILOVAS

    2014-09-01

    Full Text Available The forming conditions of biodegradable polymer films containing iodine-modified starch particles as well as the properties of the obtained films were investigated. Cationic cross-linked starch microparticles and cationic starch nanoparticles were dispersed in cellulose acetate and hydroxyethyl cellulose solution, respectively, and composite films were spin-casted. The obtained films were characterized and their mechanical properties were assessed. The cellulose acetate solution has been found to be an appropriate matrix for the dispersion of dry modified starch microparticles, but not in the case of nanoparticles. Starch nanoparticles were obtained in an aqueous medium, and the mechanical properties of the formed cellulose acetate films are significantly reduced by water present in the casting solution. It has been estimated that a fairly high amount of nanoparticles (18 wt% can be immobilized into films of water-soluble hydroxyethyl cellulose without markedly affecting the mechanical properties of the films. DOI: http://dx.doi.org/10.5755/j01.ms.20.3.5426

  10. Antifungal Activity of Brazilian Propolis Microparticles against Yeasts Isolated from Vulvovaginal Candidiasis

    Directory of Open Access Journals (Sweden)

    Kelen Fátima Dalben Dota

    2011-01-01

    Full Text Available Propolis, a resinous compound produced by Apis mellifera L. bees, is known to possess a variety of biological activities and is applied in the therapy of various infectious diseases. The aim of this study was to evaluate the in vitro antifungal activity of propolis ethanol extract (PE and propolis microparticles (PMs obtained from a sample of Brazilian propolis against clinical yeast isolates of importance in the vulvovaginal candidiasis (VVC. PE was used to prepare the microparticles. Yeast isolates (n=89, obtained from vaginal exudates of patients with VVC, were exposed to the PE and the PMs. Moreover, the main antifungal drugs used in the treatment of VVC (Fluconazole, Voriconazole, Itraconazole, Ketoconazole, Miconazole and Amphotericin B were also tested. Minimum inhibitory concentration (MIC was determined according to the standard broth microdilution method. Some Candida albicans isolates showed resistance or dose-dependent susceptibility for the azolic drugs and Amphotericin B. Non-C. albicans isolates showed more resistance and dose-dependent susceptibility for the azolic drugs than C. albicans. However, all of them were sensitive or dose-dependent susceptible for Amphotericin B. All yeasts were inhibited by PE and PMs, with small variation, independent of the species of yeast. The overall results provided important information for the potential application of PMs in the therapy of VVC and the possible prevention of the occurrence of new symptomatic episodes.

  11. Preparation and in vivo toxicity study of solid lipid microparticles as carrier for pulmonary administration.

    Science.gov (United States)

    Sanna, Vanna; Kirschvink, Nathalie; Gustin, Pascal; Gavini, Elisabetta; Roland, Isabelle; Delattre, Luc; Evrard, Brigitte

    2004-03-10

    The purpose of this research was to investigate the effects of processing conditions on the characteristics of solid lipid microparticles (SLM) with a potential application as carriers for pulmonary administration. Compritol (5.0% wt/wt) SLM dispersions were prepared by rotor-stator homogenization, at different surfactant concentrations and emulsification times. The SLM were characterized, in terms of morphology and size, after lyophilization and sterilization by autoclaving process. In vivo assessment was carried out in rats by intratracheal instillation of either placebo or SLM dispersion, and by bronchoalveolar lavage for cytological analysis. Mean particle size of 4 to 5 microm was achieved using 0.3% and 0.4% (wt/wt) of emulsifier (Poloxamer 188) and emulsification times of 2 and 5 minutes. The particles showed spherical shape and smooth surface. The morphology of microparticles, the size, and the size distribution were not substantially modified after lyophilization and sterilization. Total cell counts showed no significant differences between placebo and SLM 0.5% or 2.5% groups. Regarding cytology, percentage of polymorphonuclear neutrophils and macrophages did not significantly differ between groups. These results suggest that a single intratracheal administration of the SLMs does not induce a significant inflammatory airway response in rats and that the SLMs might be a potential carrier for encapsulated drug via the pulmonary route.

  12. Evaluation of extractant-coated magnetic microparticles for the recovery of hazardous metals from waste solution

    International Nuclear Information System (INIS)

    A magnetically assisted chemical separation (MACS) process was developed earlier at Argonne National Laboratory (ANL). This compact process was designed for the separation of transuranics (TRU) and radionuclides from the liquid waste streams that exist at many DOE sites, with an overall reduction in waste volume requiring disposal. The MACS process combines the selectivity afforded by solvent extractant/ion exchange materials with magnetic separation to provide an efficient chemical separation. Recently, the MACS process has been evaluated with acidic organophosphorus extractants for hazardous metal recovery from waste solutions. Moreover, process scale-up design issues have been addressed with respect to particle filtration and recovery. Two acidic organophosphorus compounds have been investigated for hazardous metal recovery, bis(2,4,4-trimethylpentyl) phosphinic acid (Cyanexreg-sign 272) and bis(2,4,4-trimethylpentyl) dithiophosphinic acid (Cyanexreg-sign 301). Coated onto magnetic microparticles, these extractants demonstrated superior recovery of hazardous metals from solution, relative to what was expected on the basis of results from solvent extraction experiments. The results illustrate the diverse applications of MACS technology for dilute waste streams. Preliminary process scale-up experiments with a high-gradient magnetic separator at Oak Ridge National Laboratory have revealed that very low microparticle loss rates are possible

  13. Centrifugo-pneumatic sedimentation, re-suspension and transport of microparticles.

    Science.gov (United States)

    Zhao, Y; Schwemmer, F; Zehnle, S; von Stetten, F; Zengerle, R; Paust, N

    2015-11-01

    Microparticles are widely used as solid phase for affinity-based separation. Here, we introduce a new method for automated handling of microparticles in centrifugal microfluidics that is not restricted by the particle size and requires neither auxiliary means such as magnets nor coating of microfluidic structures. All steps are initiated and controlled by the speed of rotation only. It is based on storage and "on demand" release of pneumatic energy within tunable time frames: a slow release of the pneumatic energy triggers a first fluidic path through which the supernatant above the sedimented particles is removed. An abrupt release triggers a second path which allows for liquid routing and transport of the re-suspended particles. Re-suspension of particles is thereby achieved by quickly changing the speed of rotation. We demonstrate the exchange of the particle carrier medium with a supernatant removal efficiency of more than 99.5% and a particle loss below 4%. Re-suspension and subsequent transport of suspended particles show a particle loss below 7%. The method targets the automation of particle-based assays e.g. DNA extractions and immunoassays. It is compatible with monolithic integration and suitable for mass production technologies e.g. thermoforming or injection moulding.

  14. Nanosericite as an Innovative Microparticle in Dual-Chemical Paper Retention Systems

    Directory of Open Access Journals (Sweden)

    Yuan-Shing Perng

    2013-01-01

    Full Text Available Dual-chemical retention systems based on 2 cationic polyacrylamides, a colloidal silica, and a globular anionic polymer microparticles were investigated and an exfoliated nanoparticle indigenous mica mineral, sericite, was examined for its efficacy in substituting commercial microparticle preparations. The results indicated that nanosericite generated FPR between 76.9 and 80.9% for fines and chemicals. Its ash retention values, however, were higher and tended to increase with doses of polymer, nanosericite, or Sc to between 16 and 24%. As for paper physical properties, nanosericite was not amenable to substitute the c-PAMb/polymer with only handsheet stiffness superior to the combination. Nanosericite, however, showed good substitution capacity than the c-PAMa-colloidal silica combination. Regardless of the c-PAMa doses, all examined handsheet physical properties incorporating nanosericite were superior to colloidal silica. The optimal performance was observed with c-PAMa dose of 200 ppm. Optical properties of the handsheets indicated that with nanosericite substitution, brightness values were comparable to the polymer group, while its substitution capacity for colloidal silica decreased with increasing c-PAMb dose. Only at c-PAMa dose of 300 ppm, it appeared to have good substitution for colloidal silica. Substituting nanosericite for colloidal silica appeared to reduce the c-PAMa charge and increased the overall cost effectiveness.

  15. Stabilisation effects of superparamagnetic nanoparticles on clustering in nanocomposite microparticles and on magnetic behaviour

    Energy Technology Data Exchange (ETDEWEB)

    Mandel, K., E-mail: karl-sebastian.mandel@isc.fraunhofer.de [Fraunhofer Institute for Silicate Research, ISC, Neunerplatz 2, 97082 Würzburg (Germany); University Würzburg, Chair of Chemical Technology of Materials Synthesis, Röntgenring 11, 97070 Würzburg (Germany); Hutter, F., E-mail: frank.hutter@isc.fraunhofer.de [Fraunhofer Institute for Silicate Research, ISC, Neunerplatz 2, 97082 Würzburg (Germany); Gellermann, C., E-mail: carsten.gellermann@isc.fraunhofer.de [Fraunhofer Institute for Silicate Research, ISC, Neunerplatz 2, 97082 Würzburg (Germany); Sextl, G., E-mail: gerhard.sextl@isc.fraunhofer.de [Fraunhofer Institute for Silicate Research, ISC, Neunerplatz 2, 97082 Würzburg (Germany); University Würzburg, Chair of Chemical Technology of Materials Synthesis, Röntgenring 11, 97070 Würzburg (Germany)

    2013-04-15

    Superparamagnetic nanoparticles of magnetite were coprecipitated from iron salts, dispersed with nitric acid and stabilised either by lactic acid (LA) or by a polycarboxylate-ether polymer (MELPERS4343, MP). The differently stabilised nanoparticles were incorporated into a silica matrix to form nanocomposite microparticles. The silica matrix was prepared either from tetraethylorthosilicate (TEOS) or from an aqueous sodium silicate (water glass) solution. Stabilisation of nanoparticles had a crucial influence on microparticle texture and nanoparticle distribution in the silica matrix. Magnetic measurements in combination with transmission electron microscopy (TEM) investigations suggest a uniform magnetic interaction of nanoparticles in case of LA stabilisation and magnetically interacting nanoparticle clusters of different sizes in case of MP stabilisation. Splitting of blocking temperature (T{sub B}) and irreversible temperature (T{sub ir}) in zero field cooled (ZFC) and field cooled (FC) measurements is discussed in terms of nanoparticle clustering. -- Highlights: ► Superparamagnetic nanoparticles were synthesised, dispersed and stabilised. ► Stabilisation is either via a polycarboxylate ether polymer or lactic acid. ► Stabilised nanoparticles were incorporated into silica to form composite particles. ► Depending on the stabilisation, nanoparticle clustering in the composites differed. ► Clustering influences zero field cooled/field cooled magnetic measurements.

  16. Manipulation of Self-Assembled Microparticle Chains by Electroosmotic Flow Assisted Electrorotation in an Optoelectronic Device

    Directory of Open Access Journals (Sweden)

    Xiaolu Zhu

    2015-09-01

    Full Text Available A method incorporating the optically induced electrorotation (OER and alternating current electroosmotic (ACEO effects, for the formation and motion control of microparticle chains, is numerically and experimentally demonstrated. In this method, both the rotating electric field and ACEO fluid roll are generated around the border between light and dark area of the fluidic chamber in an optoelectronic tweezers (OET device. The experimental results show that the particle chains can self-rotate in their pitch axes under the rotating electric field produced due to the different impedances of the photoconductive layer in light and dark areas, and have a peak self-rotating rate at around 1 MHz. The orbital movement of entire particle chain around the center of ACEO fluid roll can be achieved from 0.5 to 600 kHz. The strength of OER motion and ACEO-caused orbital movement of particle chains can be adjusted by changing the frequency of alternating current (AC voltage. This non-contact method has the potential for spatially regulating the posture, orientation and position of microparticle chains.

  17. Preclinical Development and In Vivo Efficacy of Ceftiofur-PLGA Microparticles

    Science.gov (United States)

    Vilos, Cristian; Velasquez, Luis A.; Rodas, Paula I.; Zepeda, Katherine; Bong, Soung-Jae; Herrera, Natalia; Cantin, Mario; Simon, Felipe; Constandil, Luis

    2015-01-01

    Drug delivery systems based on polymeric microparticles represent an interesting field of development for the treatment of several infectious diseases for humans and animals. In this work, we developed PLGA microparticles loaded with ceftiofur (PLGA-cef), a third- generation cephalosporin that is used exclusively used in animals. PLGA-cef was prepared by the double emulsion w/o/w method, and exhibited a diameter in the range of 1.5–2.2 μm, and a negative ζ potential in the range of -35 to -55 mV. The loading yield of PLGA-cef was ~7% and encapsulation efficiency was approximately 40%. The pharmacokinetic study demonstrated a sustained release profile of ceftiofur for 20 days. PLGA-cef administrated in a single dose was more effective than ceftiofur non-encapsulated in rats challenged with S. Typhimurium. The in vivo toxicological evaluation showed that PLGA-cef did not affect the blood biochemical, hematological and hemostasis parameters. Overall, the PLGA-cef showed slow in vivo release profile, high antibacterial efficacy, and low toxicity. The results obtained supports the safe application of PLGA-cef as sustained release platform in the veterinary industry. PMID:25915043

  18. Centrifugo-pneumatic sedimentation, re-suspension and transport of microparticles.

    Science.gov (United States)

    Zhao, Y; Schwemmer, F; Zehnle, S; von Stetten, F; Zengerle, R; Paust, N

    2015-11-01

    Microparticles are widely used as solid phase for affinity-based separation. Here, we introduce a new method for automated handling of microparticles in centrifugal microfluidics that is not restricted by the particle size and requires neither auxiliary means such as magnets nor coating of microfluidic structures. All steps are initiated and controlled by the speed of rotation only. It is based on storage and "on demand" release of pneumatic energy within tunable time frames: a slow release of the pneumatic energy triggers a first fluidic path through which the supernatant above the sedimented particles is removed. An abrupt release triggers a second path which allows for liquid routing and transport of the re-suspended particles. Re-suspension of particles is thereby achieved by quickly changing the speed of rotation. We demonstrate the exchange of the particle carrier medium with a supernatant removal efficiency of more than 99.5% and a particle loss below 4%. Re-suspension and subsequent transport of suspended particles show a particle loss below 7%. The method targets the automation of particle-based assays e.g. DNA extractions and immunoassays. It is compatible with monolithic integration and suitable for mass production technologies e.g. thermoforming or injection moulding. PMID:26348615

  19. Antimicrobial Properties of Microparticles Based on Carmellose Cross-Linked by Cu2+ Ions

    Directory of Open Access Journals (Sweden)

    Martina Kejdušová

    2015-01-01

    Full Text Available Carmellose (CMC is frequently used due to its high biocompatibility, biodegradability, and low immunogenicity for development of site-specific or controlled release drug delivery systems. In this experimental work, CMC dispersions in two different concentrations (1% and 2% cross-linked by copper (II ions (0.5, 1, 1.5, or 2.0 M CuCl2 were used to prepare microspheres with antimicrobial activity against Escherichia coli and Candida albicans, both frequently occurring pathogens which cause vaginal infections. The microparticles were prepared by an ionotropic gelation technique which offers the unique possibility to entrap divalent copper ions in a CMC structure and thus ensure their antibacterial activity. Prepared CMC microspheres exhibited sufficient sphericity. Both equivalent diameter and copper content were influenced by CMC concentration, and the molarity of copper (II solution affected only the copper content results. Selected samples exhibited stable but pH-responsive behaviour in environments which corresponded with natural (pH 4.5 and inflamed (pH 6.0 vaginal conditions. All the tested samples exhibited proven substantial antimicrobial activity against both Gram-negative bacteria Escherichia coli and yeast Candida albicans. Unexpectedly, a crucial parameter for microsphere antimicrobial activity was not found in the copper content but in the swelling capacity of the microparticles and in the degree of CMC surface shrinking.

  20. Glycolthermal synthesis and characterization of hexagonal CdS round microparticles in flower-like clusters

    Energy Technology Data Exchange (ETDEWEB)

    Phuruangrat, Anukorn, E-mail: phuruangrat@hotmail.com [Department of Materials Science and Technology, Faculty of Science, Prince of Songkla University, Hat Yai, Songkhla 90112 (Thailand); Ekthammathat, Nuengruethai [Department of Chemistry, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Thongtem, Titipun, E-mail: ttpthongtem@yahoo.com [Department of Chemistry, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Materials Science Research Center, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Thongtem, Somchai [Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Materials Science Research Center, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand)

    2011-10-13

    Highlights: > CdS as one of II-VI semiconducting materials. > Lab-made Teflon-lined stainless steel autoclaves enable us to form hexagonal CdS. > By 100-200 deg. C processing, round microparticles in flower clusters were synthesized. > A promising material for multiple potential applications. - Abstract: Hexagonal CdS round microparticles in flower-like clusters were synthesized by glycolthermal reactions of CdCl{sub 2} and thiourea as cadmium and sulphur sources in 1,2-propylene glycol (PG) at 100-200 deg. C for 10-30 h. Phase and morphology were detected using X-ray diffraction (XRD), and scanning and transmission electron microscopy (SEM, TEM). The products were pure phase of hexagonal wurtzite CdS. The quantitative elemental analysis of Cd:S ratio was detected using energy dispersive X-ray (EDX) analyzer. Raman spectrometer revealed the presence of fundamental and overtone modes at 296 and 595 cm{sup -1}, corresponding to the strong 1LO and weak 2LO modes, respectively. Photonic properties were investigated using UV-visible and photoluminescence (PL) spectroscopy. They showed the same absorption at 493-498 nm, and emission at 431 nm due to the excitonic recombination process. A possible formation mechanism was also proposed, according to experimental results.

  1. Numerical simulation of sedimentation of microparticles using the discrete particle method

    Institute of Scientific and Technical Information of China (English)

    Chane-Yuan Yang; Yulong Ding; Dave York; Walter Broeckx

    2008-01-01

    A mathematical model has been formulated based on the combined continuous and discrete particle method for investigating the sedimentation behaviour of microparticles in aqueous suspensions, by treating the fluid phase as continuous and the particles phase as discrete, thus allowing the behaviour of individual particles to be followed and the evolution of the structure of the particle phase to be investigated as a function of time. The model takes into account most of the prevailing forces acting on individual particles including van der Waals attractive, electrostatic repulsive, gravitational, Brownian, depletion, steric, contact and drag forces. A code has also been developed based on the model. This paper reports some preliminary modelling results of mono-dispersed microparticles settling in aqueous suspensions under various conditions. The results show the short time dynamics of the fluid phase, which has a similar order of magnitude to the particle phase. Such short time dynamics could bear significance to processes such as particle aggregation when their size becomes very small. Preliminary analyses of the results have also been carried out on the evolution of particle settling based on a newly proposed parameter, local normalised volume fraction (LNVF).

  2. Quantification of mixed-phase hybridization on polymer microparticles by europium(III) ion fluorescence.

    Science.gov (United States)

    Ketomäki, Kaisa; Lönnberg, Harri

    2007-01-01

    A protocol for quantification of oligonucleotide hybridization on polymer microparticles by europium(III) ion fluorescence is described. The procedure involves modification of commercially available amino-functionalized microparticles in such a manner that oligonucleotide probes may be assembled in situ on these particles or, alternatively, they may be immobilized postsynthetically. The oligonucleotide-coated particles obtained are then used as the solid phase in a mixed-phase hybridization assay. The efficiency of hybridization is quantified with the aid of oligonucleotides tagged with a europium(III) chelate. Either, the fluorescently tagged probe is hybridized directly to a complementary particle-anchored oligonucleotide, or a sandwich-type assay set up, where a third oligonucleotide complementary both to the tagged and particle-bound probe mediates the attachment to the particles, is exploited. The number of europium(III) ions attached to the solid-phase is determined by the DELFIA protocol, involving release of the europium(III) ions in solution and development of the fluorescence by addition of an enhancement solution. Alternatively, the fluorescence intensity of the photoluminescent chelate may be measured directly from a single particle. PMID:17984531

  3. Electrochemical Oxidation of Paracetamol Mediated by MgB2 Microparticles Modified Glassy Carbon Electrode

    Directory of Open Access Journals (Sweden)

    Mohammed Zidan

    2011-01-01

    Full Text Available A MgB2 microparticles modified glassy carbon electrode (MgB2/GCE was fabricated by adhering microparticles of MgB2 onto the electrode surface of GCE. It was used as a working electrode for the detection of paracetamol in 0.1 M KH2PO4 aqueous solution during cyclic voltammetry. Use of the MgB2/GCE the oxidation process of paracetamol with a current enhancement significantly by about 2.1 times. The detection limit of this modified electrode was found to be 30 μM. The sensitivity under conditions of cyclic voltammetry is significantly dependent on pH, supporting electrolyte, temperature and scan rate. The current enhancement observed in different electrolytic media varied in the following order: KH2PO4 > KCl > K2SO4 > KBr. Interestingly, the oxidation of paracetamol using modified GC electrode remain constant even after 15 cycling. It is therefore evident that the MgB2 modified GC electrode possesses some degree of stability. A slope of 0.52 dependent of scan rate on current indicates that the system undergoes diffusion-controlled process.

  4. Enhanced gene delivery in porcine vasculature tissue following incorporation of adeno-associated virus nanoparticles into porous silicon microparticles.

    Science.gov (United States)

    McConnell, Kellie I; Rhudy, Jessica; Yokoi, Kenji; Gu, Jianhua; Mack, Aaron; Suh, Junghae; La Francesca, Saverio; Sakamoto, Jason; Serda, Rita E

    2014-11-28

    There is an unmet clinical need to increase lung transplant successes, patient satisfaction and to improve mortality rates. We offer the development of a nanovector-based solution that will reduce the incidence of lung ischemic reperfusion injury (IRI) leading to graft organ failure through the successful ex vivo treatment of the lung prior to transplantation. The innovation is in the integrated application of our novel porous silicon (pSi) microparticles carrying adeno-associated virus (AAV) nanoparticles, and the use of our ex vivo lung perfusion/ventilation system for the modulation of pro-inflammatory cytokines initiated by ischemic pulmonary conditions prior to organ transplant that often lead to complications. Gene delivery of anti-inflammatory agents to combat the inflammatory cascade may be a promising approach to prevent IRI following lung transplantation. The rationale for the device is that the microparticle will deliver a large payload of virus to cells and serve to protect the AAV from immune recognition. The microparticle-nanoparticle hybrid device was tested both in vitro on cell monolayers and ex vivo using either porcine venous tissue or a pig lung transplantation model, which recapitulates pulmonary IRI that occurs clinically post-transplantation. Remarkably, loading AAV vectors into pSi microparticles increases gene delivery to otherwise non-permissive endothelial cells.

  5. The role of antigen specificity in the binding of murine monoclonal anti-DNA antibodies to microparticles from apoptotic cells.

    Science.gov (United States)

    Ullal, Anirudh J; Marion, Tony N; Pisetsky, David S

    2014-10-01

    Antibodies to DNA (anti-DNA) are the serological hallmark of systemic lupus erythematosus and markers of underlying immune system disturbances. These antibodies bind to both single-stranded and double-stranded DNA, mediating pathogenesis by forming immune complexes. As shown recently, DNA in blood exists in both free and particulate forms, with DNA representing an important component of microparticles. Microparticles are membrane-bound vesicles containing nuclear molecules, released by membrane blebbing during cell death and activation. A panel of monoclonal NZB/NZW F1 anti-DNA antibodies was tested for binding to microparticles generated from apoptotic THP-1 and Jurkat cells. These studies showed that only certain anti-DNA antibodies in the panel, specific for double-stranded DNA, bound to microparticles. Binding to particles was reduced by soluble DNA or DNase treatment. Together, these results indicate that particle binding is a feature of only certain anti-DNA antibodies, reflecting immunochemical properties of the antibodies and the nature of the exposed DNA antigens.

  6. Facile fabrication of uniform size-controlled microparticles and potentiality for tandem drug delivery system of micro/nanoparticles.

    Science.gov (United States)

    Iwanaga, Shintaroh; Saito, Noriaki; Sanae, Hidetoshi; Nakamura, Makoto

    2013-09-01

    This article describes a rapid and facile method for manufacturing various size-controlled gel particles with utilizing inkjet printing technology. Generally, the size of droplets could be controlled by changing nozzle heads of inkjet printer, from which ink solution is ejected. However, this method uses drying process before gelling microparticles, and with that, the size of microparticles was easily controlled by only altering the concentration of ejected solution. When sodium alginate solution with various concentrations was ejected from inkjet printer, we found that the concentration of alginate solution vs. the volume of dried alginate particle showed an almost linear relationship in the concentration range from 0.1 to 3.0%. After dried alginate particles were soaked into calcium chloride solution, the size of microgel beads were obtained almost without increasing their size. The microparticles including various sizes of nanoparticles were easily manufactured by ejecting nanoparticle-dispersed alginate solution. The release of 25-nm sized nanoparticles from alginate microgel beads was finished in a relatively-rapid manner, whereas 100-nm sized nanoparticles were partially released from those ones. Moreover, most of 250-nm sized nanoparticles were not released from alginate microgel beads even after 24-h soaking. This particle fabricating method would enable the tandem drug delivery system with a combination of the release from nano and microparticles, and be expected for the biological and tissue engineering application.

  7. Lyophilised Vegetal BM 297 ATO-Inulin lipid-based synbiotic microparticles containing Bifidobacterium longum LMG 13197: design and characterisation.

    Science.gov (United States)

    Amakiri, A C; Kalombo, L; Thantsha, M S

    2015-01-01

    This study aimed at the manufacturing and characterisation of Vegetal BM 297 ATO-inulin-Bifidobacterium longum LMG 13197 microparticles prepared by freeze drying. Emulsions containing 1%, 1.5%, 2%, 3.5% or 5% w/v inulin were prepared, with or without centrifugation before freeze drying. Morphological properties, particle size distribution, encapsulation efficiency of the microparticles and their ability to preserve viability of the enclosed B. longum LMG 13197 cells were evaluated. The microparticles produced from both formulations without a centrifugation step were irregular, porous with concavities and contained high number of bacterial cells. Formulations with or without inulin had average particle sizes of 33.4-81.0 μm with encapsulation efficiencies of 82% and 88%, respectively. Vegetal-inulin microparticles have the morphology and size that will enable their even distribution in final food products, and hence, they have the potential for use as a functional food additive because they are likely to deliver sufficient numbers of viable bacteria.

  8. Supercritical fluid assisted production of micrometric powders of the labile trypsin and chitosan/trypsin composite microparticles.

    Science.gov (United States)

    Shen, Yu-Bin; Guan, Yi-Xin; Yao, Shan-Jing

    2015-07-15

    Supercritical fluid assisted atomization introduced by a hydrodynamic cavitation mixer (SAA-HCM) was used to prepare micrometric particles of a labile protein, i.e., trypsin from aqueous solution without use of any organic solvents. The trypsin particles precipitated had various morphologies under different process conditions, with particle diameters ranging from 0.2 to 4 μm. FTIR, SDS-PAGE, CD and fluorescence spectra were performed to analyze the structural stability of the protein, and trypsin retained above 70% of the biological activity. Besides, chitosan was selected as the polymer carrier in an effort to prepare trypsin composite microparticles via SAA-HCM process. The influences of chitosan molecular weight, polymer/protein ratio and solution concentration on the particle morphology and size distribution were investigated in detail. Non-coalescing spherical composite microparticles with a narrow particle distribution (0.2-3 μm) could be obtained. The SAA-HCM prepared particles were amorphous as demonstrated by XRD and had a loading efficiency about 90%. The protein release profiles of the composite microparticles were evaluated using both the immersion condition and a Franz diffusion cell. Finally, the distribution of the protein within the particles was characterized through CLSM analysis of FITC-labeled trypsin-loaded chitosan microparticles. The SAA-HCM process is demonstrated to be a protein-friendly and promising technique for production of protein and polymer/protein composite particles formulations from aqueous solutions for drug delivery systems. PMID:25957701

  9. Formulation of insulin-loaded N-trimethyl chitosan microparticles with improved efficacy for inhalation by supercritical fluid assisted atomization.

    Science.gov (United States)

    Shen, Yu-Bin; Du, Zhe; Tang, Chuan; Guan, Yi-Xin; Yao, Shan-Jing

    2016-05-30

    Supercritical fluid assisted atomization introduced by a hydrodynamic cavitation mixer (SAA-HCM) was proposed as a green technique to fabricate insulin-loaded dry powders for inhalation administration. N-trimethyl chitosan (TMC), a polymeric mucoadhesive absorption enhancer, was synthesized and successfully micronized from aqueous solution using SAA-HCM. The prepared well-defined spherical TMC microparticles with preserved structure and thermal stability were potential carriers for delivery of proteins. Then, insulin-loaded TMC microparticles with high loading efficiency were coprecipitated from aqueous solutions using SAA-HCM without use of any organic solvents. The polymer/protein ratio revealed to be a factor influencing the particle morphology, and non-coalescing composite microparticles in amorphous state mainly ranging from 1μm to 5μm could be obtained in this work. Aerodynamic properties were assessed by next generation impactor (NGI) and the mass median aerodynamic diameter (MMAD) lied inside the inhalable range of 1-5μm, while fine particle fraction (FPF) reached above 60%. The structural integrity of encapsulated insulin was confirmed by HPLC, circular dichroism and fluorescence spectroscopy. In vivo study demonstrated that TMC could enhance the absorption and bioavailability of the pulmonarily administered insulin formulation for SD rats. These results suggest that TMC microparticles could be efficiently prepared as a promising vehicle for drug delivery, and SAA-HCM is a promising technique to prepare inhalable polymer/protein composite dry powders. PMID:27034000

  10. Numerical simulation of airflow and micro-particle deposition in human nasal airway pre- and post-virtual sphenoidotomy surgery.

    Science.gov (United States)

    Bahmanzadeh, Hojat; Abouali, Omid; Faramarzi, Mohammad; Ahmadi, Goodarz

    2015-06-01

    In the present study, the effects of endoscopic sphenoidotomy surgery on the flow patterns and deposition of micro-particles in the human nasal airway and sphenoid sinus were investigated. A realistic model of a human nasal passage including nasal cavity and paranasal sinuses was constructed using a series of CT scan images of a healthy subject. Then, a virtual sphenoidotomy by endoscopic sinus surgery was performed in the left nasal passage and sphenoid sinus. Transient airflow patterns pre- and post-surgery during a full breathing cycle (inhalation and exhalation) were simulated numerically under cyclic flow condition. The Lagrangian approach was used for evaluating the transport and deposition of inhaled micro-particles. An unsteady particle tracking was performed for the inhalation phase of the breathing cycle for the case that particles were continuously entering into the nasal airway. The total deposition pattern and sphenoid deposition fraction of micro-particles were evaluated and compared for pre- and post-surgery cases. The presented results show that sphenoidotomy increased the airflow into the sphenoid sinus, which led to increased deposition of micro-particles in this region. Particles up to 25 μm were able to penetrate into the sphenoid in the post-operation case, and the highest deposition in the sphenoid for the resting breathing rate occurred for 10 μm particles at about 1.5%. PMID:25862997

  11. Effect of particle size on the biodistribution of nano- and microparticles following intra-articular injection in mice.

    Science.gov (United States)

    Pradal, Julie; Maudens, Pierre; Gabay, Cem; Seemayer, Christian Alexander; Jordan, Olivier; Allémann, Eric

    2016-02-10

    Intra-articular (IA) injection of extended drug release forms based on biodegradable microparticles holds promise for the treatment of joint diseases. However, the fate of microparticles following intra-articular injection is controversial and has not been thoroughly investigated. The aim of this work was therefore to evaluate the biodistribution of fluorescent poly(lactic acid) particles of different sizes after IA injection in arthritic or healthy mice. Regardless of the inflammatory status of the joint, 300 nm-nanoparticles leaked from the joint. Due to inflammation and related increase of vascular permeability, 3 μm-microparticles that were retained in the non-inflamed synovial membrane leaked from the inflamed joint. Complete retention of 10 μm-microparticles was observed independently of the joint inflammatory status. Embedding particles in a hyaluronic acid gel prolonged the retention of the formulations only in inflamed joints. Depending on particle's size, formulations were preferentially eliminated by blood vessels or lymphatic pathways. Poly(lactic acid) particles of 3 μm were biocompatible and retained in knee joints at least for 6 weeks. This work highlights the need to deliver hyaluronic acid-embedded particles of at least 3 μm to guarantee their retention in inflamed joints. These results will contribute to the rational design of long-lasting formulations to treat acute and chronic joint diseases. PMID:26685724

  12. From optimization of synbiotic microparticles prepared by spray-drying to development of new functional carrot juice

    Directory of Open Access Journals (Sweden)

    Petreska-Ivanovska Tanja

    2014-01-01

    Full Text Available Lactobacillus casei loaded chitosan-Ca-alginate microparticles enriched with the prebiotic fructooligosaccharide were prepared using spray-drying method associated with the polymers complexation and cross-linking with calcium. The concentrations of the formulation factors of alginate, chitosan and CaCl2 were optimized using 23 full factorial design. Experiments showed that microparticles with favorable physicochemical properties and high probiotic viability during preparation and storage could be obtained when 40 mg/g sodium alginate, 5 mg/g chitosan and 50 mg/g CaCl2 is used. Stability of L. casei during microencapsulation was identified by FTIR spectroscopy. The viability of the probiotic in the optimal formulation of synbiotic microparticles remained above the therapeutic minimum during incubation of 24 hours in simulated gastrointestinal conditions (7.67±0.4 log cfu/g as well as after 3 months of cold storage (8.1±0.6 log cfu/g. High viability of L. casei was maintained during 6 weeks of cold storage when carrot juice was enriched with encapsulated cells. The effective preservation of L. casei into synbiotic microparticles provided production of new non-dairy functional food as an alternative of the population who is at risk of lactose intolerance.

  13. Impact of Atmospheric Microparticles on the Development of Oxidative Stress in Healthy City/Industrial Seaport Residents

    Directory of Open Access Journals (Sweden)

    Kirill Golokhvast

    2015-01-01

    Full Text Available Atmospheric microsized particles producing reactive oxygen species can pose a serious health risk for city residents. We studied the responses of organisms to microparticles in 255 healthy volunteers living in areas with different levels of microparticle air pollution. We analyzed the distribution of microparticles in snow samples by size and content. ELISA and flow cytometry methods were employed to determine the parameters of the thiol-disulfide metabolism, peroxidation and antioxidant, genotoxicity, and energy state of the leukocytes. We found that, in the park areas, microparticles with a size of 800 μm or more were predominant (96%, while in the industrial areas, they tended to be less than 50 μm (93%, including size 200–300 nm (7%. In the industrial areas, we determined the oxidative modification of proteins (21% compared to the park areas, p≤0.05 and DNA (12%, p≤0.05, as well as changes in leukocytes’ energy potential (53%, p≤0.05. An increase in total antioxidant activity (82%, p≤0.01 and thiol-disulfide system response (thioredoxin increasing by 33%, p≤0.01; glutathione, 30%, p≤0.01 with stable reductases levels maintains a balance of peroxidation-antioxidant processes, protecting cellular and subcellular structures from significant oxidative damage.

  14. Design and characterization of core-shell mPEG-PLGA composite microparticles for development of cell-scaffold constructs

    DEFF Research Database (Denmark)

    Wen, Yanhong; Gallego, Monica Ramos; Nielsen, Lene Feldskov;

    2013-01-01

    Appropriate scaffolds capable of providing suitable biological and structural guidance are of great importance to generate cell-scaffold constructs for cell-based tissue engineering. The aim of the present study was to develop composite microparticles with a structure to provide functionality as ...

  15. Radioisotopic evaluation of portal circulation

    International Nuclear Information System (INIS)

    The use of a radio-tracer of portal circulation through the intestine, should prevent cruel punctures in the portal-vein or spleen as it is usually the case with traditional methods in the study of portal-system. The absorption of I-131 and Tc-99m, previously cheked in rabbits presented similar results in dogs. The time of circulation between terminal large-intestine and the liver (t-RF) was determined by external counting at hepatic level by recording radioactivity variation-time. In healthy animals the t-RF was from 20to 60 seconds, with average time of 42 seconds. In 2 animals with partial binding of portal-vein the t-RF went up to 110 and 120 seconds. (Author)

  16. Journalism as Cultures of Circulation

    DEFF Research Database (Denmark)

    Bødker, Henrik

    2013-01-01

    The universe of journalism has always consisted of interspersed texts, meanings and practices. Yet, much journalism research has often isolated either texts and/or contexts and as such assumed relations between professional practices, informed (rational) readers and (conceived) core texts...... of journalism. It is, however, more important than ever to shift attention away from texts to the processes through which they are circulated. This is partly because the many cultural forms of journalism (textual, institutional, technological, material, behavioural and imagined) are undergoing significant......, likes, comments, searches, journalist roles, writing and reading positions and identities etc. Such forms will be traced within the mediation of a specific event with the overall aim of beginning a theorization of the landscape of journalism as highly interrelated cultures of circulation....

  17. Ocean circulation generated magnetic signals

    DEFF Research Database (Denmark)

    Manoj, C.; Kuvshinov, A.; Maus, S.;

    2006-01-01

    Conducting ocean water, as it flows through the Earth's magnetic field, generates secondary electric and magnetic fields. An assessment of the ocean-generated magnetic fields and their detectability may be of importance for geomagnetism and oceanography. Motivated by the clear identification...... of ocean tidal signatures in the CHAMP magnetic field data we estimate the ocean magnetic signals of steady flow using a global 3-D EM numerical solution. The required velocity data are from the ECCO ocean circulation experiment and alternatively from the OCCAM model for higher resolution. We assume...... of the magnetic field, as compared to the ECCO simulation. Besides the expected signatures of the global circulation patterns, we find significant seasonal variability of ocean magnetic signals in the Indian and Western Pacific Oceans. Compared to seasonal variation, interannual variations produce weaker signals....

  18. Conservation of circulation in magnetohydrodynamics

    Science.gov (United States)

    Bekenstein; Oron

    2000-10-01

    We demonstrate at both the Newtonian and (general) relativistic levels the existence of a generalization of Kelvin's circulation theorem (for pure fluids) that is applicable to perfect magnetohydrodynamics. The argument is based on the least action principle for magnetohydrodynamic flow. Examples of the new conservation law are furnished. The new theorem should be helpful in identifying new kinds of vortex phenomena distinct from magnetic ropes or fluid vortices. PMID:11089118

  19. Electronic circulation of accounting documents

    OpenAIRE

    Kremláčková, Kateřina

    2014-01-01

    This thesis describes a circulation of accounting documents in an accounting entity, deals with legal requirements of the entire process and discusses it as a part of an internal control system of the entity. In connection with the theme of the work there are also defined legislative conditions for using information and communication technologies and introduced possibilities of involving these technologies in the process of processing of the accounting documents. Above all the electronic data...

  20. Natural circulation systems: advantages and challenges

    International Nuclear Information System (INIS)

    This lecture briefly explains the principle of working of a natural circulation system, its various advantages and applications in nuclear and other industries. The major challenges to be overcome before the wide acceptance of natural circulation as the normal mode of coolant circulation in nuclear power reactors are briefly described. Classification of NCSs and the terminologies commonly encountered in natural circulation literature are also briefly explained. (author)

  1. Internal variability of the thermohaline ocean circulation

    NARCIS (Netherlands)

    Raa, Lianke Alinda te

    2003-01-01

    Variations in the ocean circulation can strongly influence climate due to the large heat transport by the ocean currents. Variability of the thermohaline ocean circulation, the part of the ocean circulation driven by density gradients, occurs typically on (inter)decadal and longer time scales and is

  2. Local delivery of cannabinoid-loaded microparticles inhibits tumor growth in a murine xenograft model of glioblastoma multiforme.

    Directory of Open Access Journals (Sweden)

    Dolores Hernán Pérez de la Ossa

    Full Text Available Cannabinoids, the active components of marijuana and their derivatives, are currently investigated due to their potential therapeutic application for the management of many different diseases, including cancer. Specifically, Δ(9-Tetrahydrocannabinol (THC and Cannabidiol (CBD - the two major ingredients of marijuana - have been shown to inhibit tumor growth in a number of animal models of cancer, including glioma. Although there are several pharmaceutical preparations that permit the oral administration of THC or its analogue nabilone or the oromucosal delivery of a THC- and CBD-enriched cannabis extract, the systemic administration of cannabinoids has several limitations in part derived from the high lipophilicity exhibited by these compounds. In this work we analyzed CBD- and THC-loaded poly-ε-caprolactone microparticles as an alternative delivery system for long-term cannabinoid administration in a murine xenograft model of glioma. In vitro characterization of THC- and CBD-loaded microparticles showed that this method of microencapsulation facilitates a sustained release of the two cannabinoids for several days. Local administration of THC-, CBD- or a mixture (1:1 w:w of THC- and CBD-loaded microparticles every 5 days to mice bearing glioma xenografts reduced tumour growth with the same efficacy than a daily local administration of the equivalent amount of those cannabinoids in solution. Moreover, treatment with cannabinoid-loaded microparticles enhanced apoptosis and decreased cell proliferation and angiogenesis in these tumours. Our findings support that THC- and CBD-loaded microparticles could be used as an alternative method of cannabinoid delivery in anticancer therapies.

  3. Local delivery of cannabinoid-loaded microparticles inhibits tumor growth in a murine xenograft model of glioblastoma multiforme.

    Science.gov (United States)

    Hernán Pérez de la Ossa, Dolores; Lorente, Mar; Gil-Alegre, Maria Esther; Torres, Sofía; García-Taboada, Elena; Aberturas, María Del Rosario; Molpeceres, Jesús; Velasco, Guillermo; Torres-Suárez, Ana Isabel

    2013-01-01

    Cannabinoids, the active components of marijuana and their derivatives, are currently investigated due to their potential therapeutic application for the management of many different diseases, including cancer. Specifically, Δ(9)-Tetrahydrocannabinol (THC) and Cannabidiol (CBD) - the two major ingredients of marijuana - have been shown to inhibit tumor growth in a number of animal models of cancer, including glioma. Although there are several pharmaceutical preparations that permit the oral administration of THC or its analogue nabilone or the oromucosal delivery of a THC- and CBD-enriched cannabis extract, the systemic administration of cannabinoids has several limitations in part derived from the high lipophilicity exhibited by these compounds. In this work we analyzed CBD- and THC-loaded poly-ε-caprolactone microparticles as an alternative delivery system for long-term cannabinoid administration in a murine xenograft model of glioma. In vitro characterization of THC- and CBD-loaded microparticles showed that this method of microencapsulation facilitates a sustained release of the two cannabinoids for several days. Local administration of THC-, CBD- or a mixture (1:1 w:w) of THC- and CBD-loaded microparticles every 5 days to mice bearing glioma xenografts reduced tumour growth with the same efficacy than a daily local administration of the equivalent amount of those cannabinoids in solution. Moreover, treatment with cannabinoid-loaded microparticles enhanced apoptosis and decreased cell proliferation and angiogenesis in these tumours. Our findings support that THC- and CBD-loaded microparticles could be used as an alternative method of cannabinoid delivery in anticancer therapies. PMID:23349970

  4. Viability of the microencapsulation of a casein hydrolysate in lipid microparticles of cupuacu butter and stearic acid

    Directory of Open Access Journals (Sweden)

    Samantha Cristina Pinho

    2013-04-01

    Full Text Available Normal 0 21 false false false PT-BR X-NONE X-NONE Solid lipid microparticles produced with a mixture of cupuacu butter and stearic acid were used to microencapsulate a commercial casein hydrolysate (Hyprol 8052. The composition of the lipid matrix used for the production of the lipid microparticles was chosen according to data on the wide angle X-ray diffraction (WAXD and differential scanning calorimetry (DSC of bulk lipid mixtures, which indicated that the presence of 10 % cupuacu butter was sufficient to significantly change the crystalline arrangement of pure stearic acid. Preliminary tests indicated that a minimum proportion of 4 % of surfactant (polysorbate 80 was necessary to produce empty spherical lipid particles with average diameters below 10 mm. The lipid microparticles were produced using 20 % cupuacu butter and 80 % stearic acid and then stabilized with 4 % of polysorbate 80, exhibiting an encapsulation efficiency of approximately 74 % of the casein hydrolysate. The melting temperature of the casein hydrolysate-loaded lipid microparticles was detected at 65.2 °C, demonstrating that the particles were solid at room temperature as expected and indicating that the incorporation of peptides had not affected their thermal behavior. After 25 days of storage, however, there was a release of approximately 30 % of the initial amount of encapsulated casein hydrolysate. This release was not thought to have been caused by the liberation of encapsulated casein hydrolysate. Instead, it was attributed to the possible desorption of the adsorbed peptides present on the surface of the lipid microparticles.

  5. Synthesis and characterization of microparticles based on poly-methacrylic acid with glucose oxidase for biosensor applications.

    Science.gov (United States)

    Hervás Pérez, J P; López-Ruiz, B; López-Cabarcos, E

    2016-03-01

    In the line of the applicability of biocompatible monomers pH and temperature dependent, we assayed poly-methacrylic acid (p-MAA) microparticles as immobilization system in the design of enzymatic biosensors. Glucose oxidase was used as enzyme model for the study of microparticles as immobilization matrices and as biological material in the performance of glucose biosensors. The enzyme immobilization method was optimized by investigating the influence of monomer concentration and cross-linker content (N',N'-methylenebisacrylamide), used in the preparation of the microparticles in the response of the biosensors. The kinetics of the polymerization and the effects of the temperature were studied, also the conversion of the polymerization was determinates by a weight method. The structure of the obtained p-MAA microparticles were studied through scanning electron microscopy (SEM) and differential scanning microscopy (DSC). The particle size measurements were performed with a Galai-Cis 1 particle analyzer system. Furthermore, the influence of the swelling behavior of hydrogel matrix as a function of pH and temperature were studied. Analytical properties such as sensitivity, linear range, response time and detection limit were studied for the glucose biosensors. The sensitivity for glucose detection obtained with poly-methacrylic acid (p-MAA) microparticles was 11.98mAM(-1)cm(-2) and 10μM of detection limit. A Nafion® layer was used to eliminate common interferents of the human serum such as uric and ascorbic acids. The biosensors were used to determine glucose in human serum samples with satisfactory results. When stored in a frozen phosphate buffer solution (pH 6.0) at -4°C, the useful lifetime of all biosensors was at least 550 days. PMID:26717846

  6. Portal Vein Embolization before Right Hepatectomy: Improved Results Using n-Butyl-Cyanoacrylate Compared to Microparticles Plus Coils

    Energy Technology Data Exchange (ETDEWEB)

    Guiu, Boris, E-mail: boris.guiu@chu-dijon.fr; Bize, Pierre; Gunthern, Daniel [Centre Hospitalo-Univeristaire Vaudois, Digestive and Oncologic Imaging and Interventional Radiology Unit, Department of Radiology and Interventional Radiology (Switzerland); Demartines, Nicolas; Halkic, Nermin [Centre Hospitalo-Univeristaire Vaudois, Department of Visceral Surgery (Switzerland); Denys, Alban [Centre Hospitalo-Univeristaire Vaudois, Digestive and Oncologic Imaging and Interventional Radiology Unit, Department of Radiology and Interventional Radiology (Switzerland)

    2013-10-15

    Background: There is currently no consensus in the literature on which embolic agent induces the greatest degree of liver hypertrophy after portal vein embolization (PVE). Only experimental results in a pig model have demonstrated an advantage of n-butyl-cyanoacrylate (NBCA) over 3 other embolic materials (hydrophilic gel, small and large polyvinyl alcohol particles) for PVE. Therefore, the aim of this human study was to retrospectively compare the results of PVE using NBCA with those using spherical microparticles plus coils. Methods: A total of 34 patients underwent PVE using either NBCA (n = 20), or spherical microparticles plus coils (n = 14). PVE was decided according to preoperative volumetry on the basis of contrast-enhanced CT. Groups were compared for age, sex, volume of the left lobe before PVE and future remnant liver ratio (FRL) (volume of the left lobe/total liver volume - tumor volume). The primary end point was the increase in left lobe volume 1 month after PVE. Secondary end points were procedure complications and biological tolerance. Results: Both groups were similar in terms of age, sex ratio, left lobe volume, and FRL before PVE. NBCA induced a greater increase in volume after PVE than did microparticles plus coils (respectively, +74 {+-} 69 % and +23 {+-} 14 %, p < 0.05). The amount of contrast medium used for the procedure was significantly larger when microparticles and coils rather than NBCA were used (respectively, 264 {+-} 43 ml and 162 {+-} 34 ml, p < 0.01). The rate of PVE complications as well as the biological tolerance was similar in both groups. Conclusion: NBCA seems more effective than spherical microparticles plus coils to induce left-lobe hypertrophy.

  7. Elevated atherosclerosis-related gene expression, monocyte activation and microparticle-release are related to increased lipoprotein-associated oxidative stress in familial hypercholesterolemia.

    Directory of Open Access Journals (Sweden)

    Morten Hjuler Nielsen

    Full Text Available Animal and in vitro studies have suggested that hypercholesterolemia and increased oxidative stress predisposes to monocyte activation and enhanced accumulation of oxidized LDL cholesterol (oxLDL-C through a CD36-dependent mechanism. The aim of this study was to investigate the hypothesis that elevated oxLDL-C induce proinflammatory monocytes and increased release of monocyte-derived microparticles (MMPs, as well as up-regulation of CD36, chemokine receptors and proinflammatory factors through CD36-dependent pathways and that this is associated with accelerated atherosclerosis in subjects with heterozygous familial hypercholesterolemia (FH, in particular in the presence of Achilles tendon xanthomas (ATX.We studied thirty FH subjects with and without ATX and twenty-three healthy control subjects. Intima-media thickness (IMT and Achilles tendon (AT thickness were measured by ultrasonography. Monocyte classification and MMP analysis were performed by flow cytometry. Monocyte expression of genes involved in atherosclerosis was determined by quantitative PCR. IMT and oxLDL-C were increased in FH subjects, especially in the presence of ATX. In addition, FH subjects had elevated proportions of intermediate CD14++CD16+ monocytes and higher circulating MMP levels. Stepwise linear regression identified oxLDL-C, gender and intermediate monocytes as predictors of MMPs. Monocyte expression of pro-atherogenic and pro-inflammatory genes regulated by oxLDL-C-CD36 interaction was increased in FH, especially in ATX+ subjects. Monocyte chemokine receptor CX3CR1 was identified as an independent contributor to IMT.Our data support that lipoprotein-associated oxidative stress is involved in accelerated atherosclerosis in FH, particularly in the presence of ATX, by inducing pro-inflammatory monocytes and increased release of MMPs along with elevated monocyte expression of oxLDL-C-induced atherosclerosis-related genes.

  8. Circulating follistatin in relation to energy metabolism.

    Science.gov (United States)

    Hansen, Jakob Schiøler; Plomgaard, Peter

    2016-09-15

    Recently, substantial evidence has emerged that the liver contributes significantly to the circulating levels of follistatin and that circulating follistatin is tightly regulated by the glucagon-to-insulin ratio. Both observations are based on investigations of healthy subjects. These novel findings challenge the present view of circulating follistatin in human physiology, being that circulating follistatin is a result of spill-over from para/autocrine actions in various tissues and cells. Follistatin as a liver-derived protein under the regulation of glucagon-to-insulin ratio suggests a relation to energy metabolism. In this narrative review, we attempt to reconcile the existing findings on circulating follistatin with the novel concept that circulating follistatin is a liver-derived molecule regulated by the glucagon-to-insulin ratio. The picture emerging is that conditions associated with elevated levels of circulating follistatin have a metabolic denominator with decreased insulin sensitivity and/or hyperglucagoneimia. PMID:27264073

  9. Effects of formulation variables on viability of L. casei loaded in whey protein-Ca alginate microparticles in simulated in vivo conditions

    OpenAIRE

    Smilkov, Katarina; Petrusevska Tozi, Lidija; Petreska Ivanovska, Tanja; Geskovski, Nikola; Petkovska, Rumenka; Glavas Dodov, Marija; Baceva, Katerina; Dimitrovski, Dejan; MLADENOVSKA, KRISTINA

    2011-01-01

    The objective of this work was to assess the influence of formulation variables of L. casei loaded whey protein-Ca-alginate microparticles on probiotic survival under different conditions, representing simulated in vivo environment.

  10. Endothelial Microparticles in Mild Chronic Obstructive Pulmonary Disease and Emphysema. The Multi-Ethnic Study of Atherosclerosis Chronic Obstructive Pulmonary Disease Study

    OpenAIRE

    Thomashow, Michael A.; Shimbo, Daichi; Parikh, Megha A.; Eric A Hoffman; Vogel-Claussen, Jens; Hueper, Katja; Fu, Jessie; Liu, Chia-Ying; Bluemke, David A.; Ventetuolo, Corey E.; Doyle, Margaret F.; Barr, R Graham

    2013-01-01

    Rationale: Basic research implicates alveolar endothelial cell apoptosis in the pathogenesis of chronic obstructive pulmonary disease (COPD) and emphysema. However, information on endothelial microparticles (EMPs) in mild COPD and emphysema is lacking.

  11. Micro-particle image velocimetry for velocity profile measurements of micro blood flows.

    Science.gov (United States)

    Pitts, Katie L; Fenech, Marianne

    2013-04-25

    Micro-particle image velocimetry (μPIV) is used to visualize paired images of micro particles seeded in blood flows. The images are cross-correlated to give an accurate velocity profile. A protocol is presented for μPIV measurements of blood flows in microchannels. At the scale of the microcirculation, blood cannot be considered a homogeneous fluid, as it is a suspension of flexible particles suspended in plasma, a Newtonian fluid. Shear rate, maximum velocity, velocity profile shape, and flow rate can be derived from these measurements. Several key parameters such as focal depth, particle concentration, and system compliance, are presented in order to ensure accurate, useful data along with examples and representative results for various hematocrits and flow conditions.

  12. Dynamics of supersonic microparticle impact on elastomers revealed by real–time multi–frame imaging

    Science.gov (United States)

    Veysset, David; Hsieh, Alex J.; Kooi, Steven; Maznev, Alexei A.; Masser, Kevin A.; Nelson, Keith A.

    2016-05-01

    Understanding high–velocity microparticle impact is essential for many fields, from space exploration to medicine and biology. Investigations of microscale impact have hitherto been limited to post–mortem analysis of impacted specimens, which does not provide direct information on the impact dynamics. Here we report real–time multi–frame imaging studies of the impact of 7 μm diameter glass spheres traveling at 700–900 m/s on elastomer polymers. With a poly(urethane urea) (PUU) sample, we observe a hyperelastic impact phenomenon not seen on the macroscale: a microsphere undergoes a full conformal penetration into the specimen followed by a rebound which leaves the specimen unscathed. The results challenge the established interpretation of the behaviour of elastomers under high–velocity impact.

  13. Functionalized magnetic microparticle-based colorimetric platform for influenza A virus detection

    Science.gov (United States)

    Chen, Chaohui; Zou, Zhong; Chen, Lu; Ji, Xinghu; He, Zhike

    2016-10-01

    A colorimetric platform for influenza A virus detection was developed by using the high efficiency of enzymatic catalysis and the reduction of gold ions with hydrogen peroxide. Aptamer-functionalized magnetic microparticles were synthesized to capture the influenza A virus. This was followed by the binding of ConA-GOx-AuNPs to the H3N2 virus through the ConA-glycan interaction. The sandwich complex was subsequently dispersed in glucose solution to trigger an enzymatic reaction to produce hydrogen peroxide, which controlled the growth of gold nanoparticles and produced colored solutions. The determination of H3N2 concentration was realized by comparing the two differently colored gold nanoparticles. This method could detect the target virus as low as 11.16 μg ml-1. Furthermore, it opens new opportunities for sensitive and colorimetric detection of viruses and proteins.

  14. Dynamics of supersonic microparticle impact on elastomers revealed by real-time multi-frame imaging.

    Science.gov (United States)

    Veysset, David; Hsieh, Alex J; Kooi, Steven; Maznev, Alexei A; Masser, Kevin A; Nelson, Keith A

    2016-01-01

    Understanding high-velocity microparticle impact is essential for many fields, from space exploration to medicine and biology. Investigations of microscale impact have hitherto been limited to post-mortem analysis of impacted specimens, which does not provide direct information on the impact dynamics. Here we report real-time multi-frame imaging studies of the impact of 7 μm diameter glass spheres traveling at 700-900 m/s on elastomer polymers. With a poly(urethane urea) (PUU) sample, we observe a hyperelastic impact phenomenon not seen on the macroscale: a microsphere undergoes a full conformal penetration into the specimen followed by a rebound which leaves the specimen unscathed. The results challenge the established interpretation of the behaviour of elastomers under high-velocity impact. PMID:27156501

  15. Rod-Shaped Magnetite Nano/Microparticles Synthesis at Ambient Temperature

    Directory of Open Access Journals (Sweden)

    Balaprasad Ankamwar

    2013-01-01

    Full Text Available Here, we reported room temperature synthesis of Fe3O4 rod-shaped nano/microparticles by chemical reduction method from FeCl3 precursor and NaBH4 as the reducing agent in the presence of the pyrrole as a capping agent. The magnetic Fe3O4 particles were characterized by several methods, such as SEM, XRD, FTIR, and TGA. The average aspect ratio of Fe3O4 rod-shaped particles was ~2.8. These particles were redispersed in deionised water to form a colloidal solution and showed magnetic properties. This economical synthesis route is scalable, and Fe3O4 particles can be exploited for various applications such as MRI contrast enhancement, biodiseperations, Ni-Fe batteries, and as a catalyst.

  16. Spontaneous pairing and cooperative movements of micro-particles in a two dimensional plasma crystal

    Energy Technology Data Exchange (ETDEWEB)

    Zhdanov, S. K. [Max Planck Institute for extraterrestrial Physics, D-85741 Garching (Germany); Couëdel, L., E-mail: lenaic.couedel@univ-amu.fr [CNRS, Université d' Aix-Marseille, PIIM UMR 7345, 13397 Marseille Cedex 20 (France); Nosenko, V.; Thomas, H. M. [Forschungsgruppe Komplexe Plasmen, Deutsches Zentrum fur Luft-und-Raumfahrt, Oberpfaffenhofen (Germany); Morfill, G. E. [Max Planck Institute for extraterrestrial Physics, D-85741 Garching (Germany); BMSTU Centre for Plasma Science and Technology, Moscow (Russian Federation)

    2015-05-15

    In an argon plasma of 20 W rf discharge at a pressure of 1.38 Pa, a stable highly ordered monolayer of microparticles is suspended. We observe spontaneous particle pairing when suddenly reducing the gas pressure. Special types of dynamical activity, in particular, entanglement and cooperative movements of coupled particles have been registered. In the course of the experiment first appeared single vertical pairs of particles, in further they gradually accumulated causing melting of the entire crystal. To record pairing events, the particle suspension is side-view imaged using a vertically extended laser sheet. The long-lasting pre-melting phase assured the credible recording and identification of isolated particle pairs. The high monolayer charge density is crucial to explain the spontaneous pairing events observed in our experiments as the mutual repulsion between the particles comprising the monolayer make its vertical extend thicker.

  17. Magneto-electrical orientation of lipid-coated graphitic micro-particles in solution

    CERN Document Server

    Nguyen, Johnny; Garcia, Isabel Llorente

    2016-01-01

    We demonstrate, for the first time, confinement of the orientation of micron-sized graphitic flakes to a well-defined plane. We orient and rotationally trap lipid-coated highly ordered pyrolytic graphite (HOPG) micro-flakes in aqueous solution using a combination of uniform magnetic and AC electric fields and exploiting the anisotropic diamagnetic and electrical properties of HOPG. Measuring the rotational Brownian fluctuations of individual oriented particles in rotational traps, we quantitatively determine the rotational trap stiffness, maximum applied torque and polarization anisotropy of the micro-flakes, as well as their dependency on the electric field frequency. Additionally, we quantify interactions of the micro-particles with adjacent glass surfaces with various surface treatments. We outline the various applications of this work, including torque sensing in biological systems.

  18. Dynamics of supersonic microparticle impact on elastomers revealed by real-time multi-frame imaging.

    Science.gov (United States)

    Veysset, David; Hsieh, Alex J; Kooi, Steven; Maznev, Alexei A; Masser, Kevin A; Nelson, Keith A

    2016-05-09

    Understanding high-velocity microparticle impact is essential for many fields, from space exploration to medicine and biology. Investigations of microscale impact have hitherto been limited to post-mortem analysis of impacted specimens, which does not provide direct information on the impact dynamics. Here we report real-time multi-frame imaging studies of the impact of 7 μm diameter glass spheres traveling at 700-900 m/s on elastomer polymers. With a poly(urethane urea) (PUU) sample, we observe a hyperelastic impact phenomenon not seen on the macroscale: a microsphere undergoes a full conformal penetration into the specimen followed by a rebound which leaves the specimen unscathed. The results challenge the established interpretation of the behaviour of elastomers under high-velocity impact.

  19. Formation of a protection film on the human skin by microparticles

    International Nuclear Information System (INIS)

    Laser scanning microscopy and tape stripping, in combination with optical methods, were used to analyze the distribution and penetration of a barrier cream into the horny layer (stratum corneum) of the human skin under in vivo conditions. The barrier cream contained microparticles of 10 – 100 μm loaded with antioxidant substances. The cream was designed for protection of the skin surface against the destructive action of free radicals, produced by systemically applied chemotherapeutic agents reaching the skin surface via the sweat. Both methods were able to demonstrate that the barrier cream was distributed homogeneously on the skin surface forming a protection film. A penetration into deeper parts of the stratum corneum (SC) was not observed

  20. Trapping and Driving Individual Charged Micro-particles in Fluid with an Electrostatic Device

    Institute of Scientific and Technical Information of China (English)

    Jingjing Xu; Zijing Lei; Jingkun Guo; Jie Huang; Wei Wang; Uta Reibetanz; Shengyong Xu

    2016-01-01

    A variety of micro-tweezers techniques, such as optical tweezers, magnetic tweezers, and dielectrophoresis technique, have been applied intensively in precise characterization of micro/nanoparticles and bio-molecules. They have contributed remarkably in better understanding of working mechanisms of individual sub-cell organelles, proteins, and DNA. In this paper, we present a controllable electrostatic device embedded in a microchannel, which is capable of driving, trapping, and releasing charged micro-particles suspended in microfluid, demonstrating the basic concepts of electrostatic tweezers. Such a device is scalable to smaller size and offers an alternative to currently used micro-tweezers for application in sorting, selecting, manipulating, and analyzing individual micro/nanoparticles. Furthermore, the system offers the potential in being combined with dielectrophoresis and other techniques to create hybrid micro-manipulation systems.

  1. Sample preparation for measurement of plasma mycophenolic acid concentrations using chromatographically functionalized magnetic micro-particles.

    Science.gov (United States)

    König, Katrin; Vogeser, Michael

    2012-01-01

    Utilizing chromatographically modified magnetic micro-particles is an innovative principle of sample preparation for quantitative analysis of small molecules in complex biomedical samples by liquid chromatography tandem mass spectrometry. Since no vacuum or pressure has to be applied-in contrast to cartridge based solid phase extraction protocols-the principle's main characteristics are potentially straightforward automation and a high extraction performance (in terms of µg of extraction material per µL of sample). Following first descriptions of the approach, this article reports, the validation of a magnetic particle-based, analytical method for the quantification of the immunosuppressant mycophenolic acid in plasma. This sample preparation technology has shown a good performance for this clinically relevant analyte. As a result, we conclude that further work towards the implementation of this technology in a multi- analyte approach on robotic systems, aiming towards a fully automated process, is justified. PMID:23221116

  2. Optofluidic tunable manipulation of microparticles by integrating graded-index fiber taper with a microcavity.

    Science.gov (United States)

    Gong, Yuan; Zhang, Chenlin; Liu, Qun-Feng; Wu, Yu; Wu, Huijuan; Rao, Yunjiang; Peng, Gang-Ding

    2015-02-01

    We propose and demonstrate optofluidic tunable manipulation of polystyrene microparticles based on the combination of a graded-index fiber (GIF) taper and a microcavity. The tunability on the manipulation length is experimentally explored by changing the balance between the optical force and the microfluidic flow force, as well as by tuning the focus of light emitting from the GIF taper via adjusting the length of an air microcavity. By optimizing the geometric shape of the GIF taper, as well as the flow rate and laser power, a manipulation length of 177 μm is achieved, more than 4 times longer than the state-of-the-art optical fiber tweezers. This method has advantages of high flexibility, ease of fabrication and use, integration with microfluidics and has the potential for optofluidic sensing applications. PMID:25836228

  3. Self assembly of microparticles in stable ring structures in an optical trap

    CERN Document Server

    Haldar, Arijit; Roy, Basudev; Gupta, S Dutta; Banerjee, Ayan

    2011-01-01

    Micro-particle self assembly under the influence of optical forces produced by higher order optical beams or by projection of a hologram into the trapping volume is well known. In this paper, we report the spontaneous formation of a ring of identical microspheres (each with diameter 1.1 um in conventional single beam optical tweezers having standing wave geometry with the sample chamber consisting of a cover slip and glass slide, and a usual TEM00 Gaussian beam. The effects of different experimental parameters on the ring formation are studied extensively. The experimental observations are backed by theoretical simulations based on a plane wave decomposition of the forward and backward propagating Gaussian beams. The ring patterns are shown to be caused due to geomterical aberrations produced by focusing the Gaussian beam using a high numerical aperture microscope objective into stratified media. It is found that the thickness of the stratified media and the standing wave geometry itself play a critical role ...

  4. Physicochemical aspects involved in methotrexate release kinetics from biodegradable spray-dried chitosan microparticles

    Science.gov (United States)

    Mesquita, Philippe C.; Oliveira, Alice R.; Pedrosa, Matheus F. Fernandes; de Oliveira, Anselmo Gomes; da Silva-Júnior, Arnóbio Antônio

    2015-06-01

    Spray dried methotrexate (MTX) loaded chitosan microparticles were prepared using different drug/copolymer ratios (9%, 18%, 27% and 45% w/w). The physicochemical aspects were assessed in order to select particles that were able to induce a sustained drug release effect. Particles were successfully produced which exhibited desired physicochemical aspects such as spherical shape and high drug loading. XRD and FT-IR analysis demonstrated that drug is not bound to copolymer and is only homogeneously dispersed in an amorphous state into polymeric matrix. Even the particles with higher drug loading levels presented a sustained drug release profile, which were mathematically modeled using adjusted Higuchi model. The drug release occurred predominantly with drug dissolution and diffusion through swollen polymeric matrix, with the slowest release occurring with particles containing 9% of drug, demonstrating an interesting and promising drug delivery system for MTX.

  5. Change in surface of polymer materials upon irradiation of accelerated micro-particles

    Energy Technology Data Exchange (ETDEWEB)

    Kudo, Hisaaki [Nuclear Engineering Research Laboratory, School of Engineering, University of Tokyo, 2-22 Shirakata-Shirane, Tokai, Ibaraki 319-1188 (Japan)]. E-mail: hkudo@utnl.jp; Tadokoro, Masashi [Nuclear Engineering Research Laboratory, School of Engineering, University of Tokyo, 2-22 Shirakata-Shirane, Tokai, Ibaraki 319-1188 (Japan); Narita, Shintaro [Nuclear Engineering Research Laboratory, School of Engineering, University of Tokyo, 2-22 Shirakata-Shirane, Tokai, Ibaraki 319-1188 (Japan); Matsuoka, Leo [Nuclear Engineering Research Laboratory, School of Engineering, University of Tokyo, 2-22 Shirakata-Shirane, Tokai, Ibaraki 319-1188 (Japan); Muroya, Yusa [Nuclear Engineering Research Laboratory, School of Engineering, University of Tokyo, 2-22 Shirakata-Shirane, Tokai, Ibaraki 319-1188 (Japan); Katsumura, Yosuke [Nuclear Engineering Research Laboratory, School of Engineering, University of Tokyo, 2-22 Shirakata-Shirane, Tokai, Ibaraki 319-1188 (Japan)

    2005-07-01

    As a new method of use of a particle accelerator (ionizing radiation generator), we irradiated accelerated micro-particles of silver (Ag) onto polymer materials such as polyimides, glass, ceramics and semi-conductors. The particles can be generated at a Van de Graaff electrostatic accelerator operating at 1-3 MV. The velocity was around 1-10 km/s, size of diameter was about 1-10 {mu}m and charge was about 1-2 {mu}C. We investigated the change in surface of materials upon irradiation, by using laser microscope, atomic force microscope and scanning electron microscope. Crater-shaped irradiation spots having limb structure were found, and their diameter and depth were evaluated, ranging in a few micrometers. The planar distribution of the projectile around the irradiation spot was examined with energy dispersive X-ray spectroscopy. Correlation between size of the irradiation spots and kinetic energy of the accelerated micro-particles was investigated, and compared with an empirical formula and molecular dynamics study. Numerical simulation dealing with dynamic behaviour of elastic structure was carried out based on SPH (Smoothed Particle Hydrodynamics) method, a kind of (virtual) particle method. The simulation also found that a crater-shaped spot having limb structure is formed upon collision of the accelerated projectile with the target-materials. The results of simulation were compared with the experimental observations. These experiment and simulation are important for the evaluation of damages and resistance of polymer materials used in the space, such as the thermal control material, and cover glass of solar cells etc., towards space debris and dusts. It would be complement the on-ground radiation resistant tests on the materials conducted by using electron and ion beam accelerators.

  6. PEGylation of magnetic poly(glycidyl methacrylate) microparticles for microfluidic bioassays

    Energy Technology Data Exchange (ETDEWEB)

    Kucerova, Jana; Svobodova, Zuzana [Department of Biological and Biochemical Sciences, Faculty of Chemical Technology, University of Pardubice, Studentska 573, 53210 Pardubice (Czech Republic); Knotek, Petr [Joint Laboratory of Solid State Chemistry of IMC and University of Pardubice, Faculty of Chemical Technology, University of Pardubice, Studentska 573, 53210 Pardubice (Czech Republic); Palarcik, Jiri [Institute of Environmental and Chemical Engineering, Faculty of Chemical Technology, University of Pardubice, Studentska 573, 53210 Pardubice (Czech Republic); Vlcek, Milan; Kincl, Miloslav; Horak, Daniel [Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic, Heyrovsky Sq. 2, 16206 Prague 6 (Czech Republic); Autebert, Julien; Viovy, Jean-Louis [Macromolecules and Microsystems in Biology and Medicine, Institute Curie, UMR 168, 26 Rue d' Ulm, 75005 Paris (France); Bilkova, Zuzana, E-mail: zuzana.bilkova@upce.cz [Department of Biological and Biochemical Sciences, Faculty of Chemical Technology, University of Pardubice, Studentska 573, 53210 Pardubice (Czech Republic)

    2014-07-01

    In this study, magnetic poly(glycidyl methacrylate) microparticles containing carboxyl groups (PGMA-COOH) were coated using highly hydrophilic polymer poly(ethylene glycol) (PEG). PEG was used to reduce nonspecific interactions with proteins and cells while decreasing adhesion of particles to the walls of a microfluidic devices from poly(dimethylsiloxane) (PDMS) and cyclic olefin copolymer (COC). Zeta potential measurement, infrared spectroscopy, scanning electron microscopy, anti-PEG ELISA assay, and bioaffinity interactions between biotin and streptavidin-HRP successfully proved the presence of PEG on the surface of microspheres. Both neat and PEGylated microspheres were then incubated with the inert protein bovine serum albumin or cells to evaluate the rate of nonspecific adsorption (NSA). PEG with Mr of 30,000 Da was responsible for 45% reduction in NSA of proteins and 74% for cells compared to neat particles. The microspheres' behavior in PDMS and COC microchannels was then evaluated. Aggregation and adhesion of PEGylated microspheres significantly decreased compared to neat particles. Finally, the model enzyme horseradish peroxidase was immobilized on the microspheres through the heterobifunctional PEG chain. The possibility for subsequent covalent coupling of the ligand of interest was confirmed. Such PEGylated microparticles can be efficiently used in PDMS microchips as a carrier for bioaffinity separation or of enzyme for catalysis. - Highlights: • Magnetic polymer microspheres with highly hydrophilic PEG coating were prepared. • PEG reduced microsphere adhesion in microchannels versus neat particles. • Suitability of methods for detecting PEG on magnetic microspheres was investigated. • PEG on microsphere surfaces decreased nonspecific adsorption of proteins and cells.

  7. Interest of cyclodextrins in spray-dried microparticles formulation for sustained pulmonary delivery of budesonide.

    Science.gov (United States)

    Dufour, Gilles; Bigazzi, William; Wong, Nelson; Boschini, Frederic; de Tullio, Pascal; Piel, Geraldine; Cataldo, Didier; Evrard, Brigitte

    2015-11-30

    To achieve an efficient lung delivery and efficacy, both active ingredient aerosolisation properties and permeability through the lung need to be optimized. To overcome these challenges, the present studies aim to develop cyclodextrin-based spray-dried microparticles containing a therapeutic corticosteroid (budesonide) that could be used to control airway inflammation associated with asthma. The complexation between budesonide and hydroxypropyl-β-cyclodextrin (HPBCD) has been investigated. Production of inhalation powders was carried out using a bi-fluid nozzle spray dryer and was optimized based on a design of experiments. Spray-dried microparticles display a specific "deflated-ball like shape" associated with an appropriate size for inhalation. Aerodynamic assessment show that the fine particle fraction was increased compared to a classical lactose-based budesonide formulation (44.05 vs 26.24%). Moreover, the budesonide permeability out of the lung was shown to be reduced in the presence of cyclodextrin complexes. The interest of this sustained budesonide release was evaluated in a mouse model of asthma. The anti-inflammatory effect was compared to a non-complexed budesonide formulation at the same concentration and attests the higher anti-inflammatory activity reach with the cyclodextrin-based formulation. This strategy could therefore be of particular interest for improving lung targeting while decreasing systemic side effects associated with high doses of corticosteroids. In conclusion, this works reports that cyclodextrins could be used in powder for inhalation, both for their abilities to improve active ingredient aerosolisation properties and further to their dissolution in lung fluid, to decrease permeability out of the lungs leading to an optimized activity profile.

  8. Interest of cyclodextrins in spray-dried microparticles formulation for sustained pulmonary delivery of budesonide.

    Science.gov (United States)

    Dufour, Gilles; Bigazzi, William; Wong, Nelson; Boschini, Frederic; de Tullio, Pascal; Piel, Geraldine; Cataldo, Didier; Evrard, Brigitte

    2015-11-30

    To achieve an efficient lung delivery and efficacy, both active ingredient aerosolisation properties and permeability through the lung need to be optimized. To overcome these challenges, the present studies aim to develop cyclodextrin-based spray-dried microparticles containing a therapeutic corticosteroid (budesonide) that could be used to control airway inflammation associated with asthma. The complexation between budesonide and hydroxypropyl-β-cyclodextrin (HPBCD) has been investigated. Production of inhalation powders was carried out using a bi-fluid nozzle spray dryer and was optimized based on a design of experiments. Spray-dried microparticles display a specific "deflated-ball like shape" associated with an appropriate size for inhalation. Aerodynamic assessment show that the fine particle fraction was increased compared to a classical lactose-based budesonide formulation (44.05 vs 26.24%). Moreover, the budesonide permeability out of the lung was shown to be reduced in the presence of cyclodextrin complexes. The interest of this sustained budesonide release was evaluated in a mouse model of asthma. The anti-inflammatory effect was compared to a non-complexed budesonide formulation at the same concentration and attests the higher anti-inflammatory activity reach with the cyclodextrin-based formulation. This strategy could therefore be of particular interest for improving lung targeting while decreasing systemic side effects associated with high doses of corticosteroids. In conclusion, this works reports that cyclodextrins could be used in powder for inhalation, both for their abilities to improve active ingredient aerosolisation properties and further to their dissolution in lung fluid, to decrease permeability out of the lungs leading to an optimized activity profile. PMID:26410753

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

    Science.gov (United States)

    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. PMID:24511214

  10. Use of human amelogenin in molecular encapsulation for the design of pH responsive microparticles

    Directory of Open Access Journals (Sweden)

    Bonde Johan

    2012-05-01

    Full Text Available Abstract Background Proteins can be used in drug delivery systems to improve pharmacological properties of an active substance. Differences in pH between tissues can be utilized in order to achieve a targeted drug release at a specific location or tissue, such as a tumor. The enamel matrix protein amelogenin has a pH dependent solubility profile and self-assemble to form aggregates at neutral pH. This could make amelogenin useful in the design of pH responsive drug delivery systems. Results In this study amelogenin was evaluated as a pH responsive component in drug delivery applications. This was achieved by testing the ability of amelogenin to entrap/release other proteins upon changes in pH, and by testing if amelogenin could confer pH responsiveness to an existing and versatile drug delivery system, such as gelatin microparticles. Amelogenin was able to encapsulate bovine serum albumin and insulin, whichwere used as model target proteins. The composite aggregates of amelogenin and target protein were formed at neutral pH and could be reversibly solubilized at weakly acidic pH. Gelatin microparticles prepared in the presence of amelogenin, showed a modulated structure in response to pH change, when studied by scanning electron microscopy, compared to particles without amelogenin. At neutral pH amelogenin induced formation of pores in the particle surface, which were not present at acidic pH, or in particles lacking amelogenin. Conclusions The results from this study demonstrate that amelogenin can be a useful component in drug delivery systems in order to achieve a pH dependent response.

  11. Contactless and non-invasive delivery of micro-particles lying on a non-customized rigid surface by using acoustic radiation force.

    Science.gov (United States)

    Meng, Jianxin; Mei, Deqing; Jia, Kun; Fan, Zongwei; Yang, Keji

    2014-07-01

    In the existing acoustic micro-particle delivery methods, the micro-particles always lie and slide on the surface of platform in the whole delivery process. To avoid the damage and contamination of micro-particles caused by the sliding motion, this paper deals with a novel approach to trap micro-particles from non-customized rigid surfaces and freely manipulate them. The delivery process contains three procedures: detaching, transporting, and landing. Hence, the micro-particles no longer lie on the surface, but are levitated in the fluid, during the long range transporting procedure. It is very meaningful especially for the fragile and easily contaminated targets. To quantitatively analyze the delivery process, a theoretical model to calculate the acoustic radiation force exerting upon a micro-particle near the boundary in half space is built. An experimental device is also developed to validate the delivery method. A 100 μm diameter micro-silica bead adopted as the delivery target is detached from the upper surface of an aluminum platform and levitated in the fluid. Then, it is transported along the designated path with high precision in horizontal plane. The maximum deviation is only about 3.3 μm. During the horizontal transportation, the levitation of the micro-silica bead is stable, the maximum fluctuation is less than 1 μm. The proposed method may extend the application of acoustic radiation force and provide a promising tool for microstructure or cell manipulation. PMID:24568691

  12. Endothelial microparticles (EMP for the assessment of endothelial function: an in vitro and in vivo study on possible interference of plasma lipids.

    Directory of Open Access Journals (Sweden)

    Sabrina H van Ierssel

    Full Text Available BACKGROUND: Circulating endothelial microparticles (EMP reflect the condition of the endothelium and are of increasing interest in cardiovascular and inflammatory diseases. Recently, increased numbers of EMP following oral fat intake, possibly due to acute endothelial injury, have been reported. On the other hand, the direct interference of lipids with the detection of EMP has been suggested. This study aimed to investigate the effect of lipid-rich solutions, commonly administered in clinical practice, on the detection, both in vitro and in vivo, of EMP. METHODS: For the in vitro assessment, several lipid-rich solutions were added to whole blood of healthy subjects (n = 8 and patients with coronary heart disease (n = 5. EMP (CD31+/CD42b- were detected in platelet poor plasma by flow cytometry. For the in vivo study, healthy volunteers were evaluated on 3 different study-days: baseline evaluation, following lipid infusion and after a NaCl infusion. EMP quantification, lipid measurements and peripheral arterial tonometry were performed on each day. RESULTS: Both in vitro addition and in vivo administration of lipids significantly decreased EMP (from 198.6 to 53.0 and from 272.6 to 90.6/µl PPP, respectively, p = 0.001 and p = 0.012. The EMP number correlated inversely with the concentration of triglycerides, both in vitro and in vivo (r = -0.707 and -0.589, p<0.001 and p = 0.021, respectively. The validity of EMP as a marker of endothelial function is supported by their inverse relationship with the reactive hyperemia index (r = -0.758, p = 0.011. This inverse relation was confounded by the intravenous administration of lipids. CONCLUSION: The confounding effect of high circulating levels of lipids, commonly found in patients that receive intravenous lipid-based solutions, should be taken into account when flow cytometry is used to quantify EMP.

  13. A blood circulation model for reference man

    Energy Technology Data Exchange (ETDEWEB)

    Leggett, R.W.; Eckerman, K.F. [Oak Ridge National Lab., TN (United States). Health Sciences Research Div.; Williams, L.R. [Indiana Univ., South Bend, IN (United States). Div. of Liberal Arts and Sciences

    1999-01-01

    This paper describes a dynamic blood circulation model that predicts the movement and gradual dispersal of a bolus of material in the circulation after its intravascular injection into an adult human. The main purpose of the model is to improve the dosimetry of internally deposited radionuclides that decay in the circulation to a significant extent. The total blood volume is partitioned into the blood contents of 24 separate organs or tissues, right heart chambers, left heart chambers, pulmonary circulation, arterial outflow to the systemic tissues (aorta and large arteries), and venous return from the systemic tissues (large veins). As a compromise between physical reality and computational simplicity, the circulation of blood is viewed as a system of first-order transfers between blood pools, with the delay time depending on the mean transit time across the pool. The model allows consideration of incomplete, tissue-dependent extraction of material during passage through the circulation and return of material from tissues to plasma.

  14. Circulation of Venus upper mesosphere.

    Science.gov (United States)

    Zasova, Ludmila; Gorinov, Dmitry; Shakun, Alexey; Altieri, Francesca; Migliorini, Alessandra; Piccioni, Giuseppe; Drossart, Pierre

    2014-05-01

    Observation of the O2 1.27 μm airglow intensity distribution on the night side of Venus is one of the methods of study of the circulation in upper mesosphere 90-100 km. VIRTIS-M on board Venus Express made these observations in nadir and limb modes in Southern and Northern hemispheres respectively. Global map of the O2 night glow is published (Piccioni et al. 2009). In this work we use for analysis only data, obtained with exposure > 3 s to avoid high noisy data. It was found that intensity of emission decreases to poles and to terminators (similar to Piccioni et al.2009) in both hemispheres, which gives evidence for existence of SS-AS circulation with transport of the air masses through poles and terminators with ascending/descending flows at SS/AS areas. However, asymmetry of distribution of intensity of airglow is observed in both hemispheres. Global map for southern hemisphere (from nadir data) has good statistics at φ > 10-20° S and pretty poor at low latitude. Maximum emission is shifted from midnight by 1 - 2 hours to the evening (22-23h) and deep minimum of emission is found at LT=2-4 h at φ > 20° S. This asymmetry is extended up to equatorial region, however statistic is poor there. No evident indication for existence of the Retrograde Zonal Superrotation (RZS) is found: maximum emission in this case, which is resulting from downwards flow, should be shifted to the morning. The thermal tides, gravity waves are evidently influence on the night airglow distribution. VIRTIS limb observations cover the low northern latitudes and they are more sparse at higher latitudes. Intensity of airglow at φ = 0 - 20° N shows wide maximum, which is shifted by 1- 2 h from midnight to morning terminator. This obviously indicates that observed O2 night glow distribution in low North latitudes is explained by a superposition of SS-AS flow and RZS circulation at 95-100 km. This behavior is similar to the NO intensity distribution, obtained by SPICAV.

  15. Theoretical Study of Large-Angle Bending Transport of Microparticles by 2D Acoustic Half-Bessel Beams.

    Science.gov (United States)

    Li, Yixiang; Qiu, Chunyin; Xu, Shengjun; Ke, Manzhu; Liu, Zhengyou

    2015-01-01

    Conventional microparticle transports by light or sound are realized along a straight line. Recently, this limit has been overcome in optics as the growing up of the self-accelerating Airy beams, which are featured by many peculiar properties, e.g., bending propagation, diffraction-free and self-healing. However, the bending angles of Airy beams are rather small since they are only paraxial solutions of the two-dimensional (2D) Helmholtz equation. Here we propose a novel micromanipulation by using acoustic Half-Bessel beams, which are strict solutions of the 2D Helmholtz equation. Compared with that achieved by Airy beams, the bending angle of the particle trajectory attained here is much steeper (exceeding 90(o)). The large-angle bending transport of microparticles, which is robust to complex scattering environment, enables a wide range of applications from the colloidal to biological sciences. PMID:26279478

  16. Spherical microparticles with Saturn ring defects and their self-assembly across the nematic to smectic-A phase transition

    Science.gov (United States)

    Zuhail, K. P.; Čopar, S.; Muševič, I.; Dhara, Surajit

    2015-11-01

    We report experimental studies on the Saturn ring defect associated with a spherical microparticle across the nematic (N ) to smectic-A (Sm A ) phase transition. We observe that the director distortion around the microparticle changes rapidly with temperature. The equilibrium interparticle separation and the angle between two quadrupolar particles in the N phase are larger than those of the Sm A phase. They are almost independent of the temperature in both phases, except for a discontinuous jump at the transition. We assembled a few particles using a laser tweezer to form a two-dimensional colloidal crystal in the N phase. The lattice structure of the crystal dissolves irreversibly across the N -Sm A phase transition. The results on the pretransitional behavior of the defect are supported by the Landau-de Gennes Q -tensor modeling.

  17. Linear thermal circulator based on Coriolis forces.

    Science.gov (United States)

    Li, Huanan; Kottos, Tsampikos

    2015-02-01

    We show that the presence of a Coriolis force in a rotating linear lattice imposes a nonreciprocal propagation of the phononic heat carriers. Using this effect we propose the concept of Coriolis linear thermal circulator which can control the circulation of a heat current. A simple model of three coupled harmonic masses on a rotating platform permits us to demonstrate giant circulating rectification effects for moderate values of the angular velocities of the platform.

  18. The Ten Relationships in Rural Land Circulation

    OpenAIRE

    Cai, Zhirong; Ren, Shuo; Zhang, Zhigang

    2009-01-01

    The ten relationships during land circulation are discussed. Among them, the relationship between peasant household and government indicates that government should only carry out its service and regulatory functions and farmers should be the main body of land circulation, because peasants usually have no discourse power during land circulation. In the relationship between land ownership and contracting management right, we mainly discuss the transfer of land contracting management right and p...

  19. The aerodynamics of circulation control

    Science.gov (United States)

    Wood, N. J.

    1981-01-01

    Two dimensional subsonic wind tunnel tests were conducted on a 20% thickness: chord ratio circulation controlled elliptic aerofoil section equipped with forward and reverse blowing slots. Overall performance measurements were made over a range of trailing edge blowing momentum coefficients from 0 to 0.04; some included the effect of leading edge blowing. A detailed investigation of the trailing edge wall jet, using split film probes, hot wire probes and total head tubes, provided measurements of mean velocity components, Reynolds normal and shear stresses, and radial static pressure. The closure of the two dimensional angular momentum and continuity equations was examined using the measured data, with and without correction, and the difficulty of obtaining a satisfactory solution illustrated. Suggestions regarding the nature of the flow field which should aid the understanding of Coanda effect and the theoretical solution of highly curved wall jet flows are presented.

  20. Irregular Labellings of Circulant Graphs

    OpenAIRE

    Anholcer, Marcin

    2011-01-01

    We investigate the \\textit{irregularity strength} ($s(G)$) and \\textit{total vertex irregularity strength} ($tvs(G)$) of circulant graphs $Ci_n(1,2,...,k)$ and prove that $tvs(Ci_n(1,2,...,k))=\\lceil\\frac{n+2k}{2k+1}\\rceil$, while $s(Ci_n(1,2,...,k))=\\lceil\\frac{n+2k-1}{2k}\\rceil$ except the case when $(n \\bmod 4k = 2k+1 \\wedge k\\bmod 2=1) \\vee n=2k+1$ and $s(Ci_n(1,2,...,k))=\\lceil\\frac{n+2k-1}{2k}\\rceil+1$.