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Sample records for alginate microspheres prepared

  1. PLGA/alginate composite microspheres for hydrophilic protein delivery.

    PubMed

    Zhai, Peng; Chen, X B; Schreyer, David J

    2015-11-01

    Poly(lactic-co-glycolic acid) (PLGA) microspheres and PLGA/alginate composite microspheres were prepared by a novel double emulsion and solvent evaporation technique and loaded with bovine serum albumin (BSA) or rabbit anti-laminin antibody protein. The addition of alginate and the use of a surfactant during microsphere preparation increased the encapsulation efficiency and reduced the initial burst release of hydrophilic BSA. Confocal laser scanning microcopy (CLSM) of BSA-loaded PLGA/alginate composite microspheres showed that PLGA, alginate, and BSA were distributed throughout the depths of microspheres; no core/shell structure was observed. Scanning electron microscopy revealed that PLGA microspheres erode and degrade more quickly than PLGA/alginate composite microspheres. When loaded with anti-laminin antibody, the function of released antibody was well preserved in both PLGA and PLGA/alginate composite microspheres. The biocompatibility of PLGA and PLGA/alginate microspheres were examined using four types of cultured cell lines, representing different tissue types. Cell survival was variably affected by the inclusion of alginate in composite microspheres, possibly due to the sensitivity of different cell types to excess calcium that may be released from the calcium cross-linked alginate.

  2. Preparation and characterization of rifampicin-PLGA microspheres/sodium alginate in situ gel combination delivery system.

    PubMed

    Hu, Chunhui; Feng, Hanzhou; Zhu, Chunyan

    2012-06-15

    We prepared a complex drug delivery system consisted of rifampicin-poly(lactic-co-glycolic acid) (PLGA) microspheres in combination with sodium alginate in situ gel. The microspheres were obtained by using a solvent evaporation method, the mean diameter was 1.748 μm and the span of particle distribution was 0.78. The combination delivery system was obtained by adding microspheres to sodium alginate solution followed by physically mixing. In an in vitro study of drug release monitored for 11 days, the release of rifampicin from combination delivery system was slower than microspheres. The cumulative release percent of rifampicin from combination delivery system was 91.83 ± 1.26%, which was lower than 97.36 ± 3.41% of rifampicin released from microspheres. An in vivo fluorescence imaging study suggests that the gel adhered to lungs within 24h, and microspheres stayed in lungs at least for 504 h (21 days). In vivo drug release study indicates that the maximum local rifampicin concentration in lungs was 48.60 ± 15.67 μg mL(-1) 5h after administration. After 21 days, the local rifampicin concentration was 0.81±0.14μgmL(-1), which was above the minimum inhibitory concentration of rifampicin. The combination delivery system significantly prolonged RFP release compared to microspheres, from which RFP released could only be detected for 10 days. This approach to control the release of rifampicin using PLGA microspheres/in situ gel combination delivery system in conjunction with interventional technology is useful for improving anti-tuberculosis treatment effectiveness for patients.

  3. Preparation and characterization of Ganoderma lucidum spores-loaded alginate microspheres by electrospraying.

    PubMed

    Zhao, Ding; Li, Jing-Song; Suen, William; Chang, Ming-Wei; Huang, Jie

    2016-05-01

    Ganoderma lucidum spores (GLSs), popular functional food in preventive medicine, are susceptible to oxidative and acidic degradation during processing, storage and oral administration, resulting in the loss of sensory and nutritional qualities. The main objective of the study was to encapsulate the GLS in order to fully preserve the bioactivity of the ingredients as well as providing controlled and targeted delivery. Electrospraying was applied to prepare GLS-Alginate (GLS/A) micro beads in the current study. The size of GLS/A beads can be tailored by varying the applied voltage and drying processes. pH responsive release profiles of GLS/A beads were revealed from in vitro study in a simulated gastrointestinal environment: no release of GLS encapsulated beads in the simulated gastric fluid (pH of 1.8) was observed; while a rapid, size dependent release was found in the simulated intestinal solution (pH of 7.5). The release from smaller beads (e.g. 600 μm) was 1.5 times faster than that of larger beads (e.g. 2000 μm). In addition, the GLS release from freeze dried beads was almost 3 times faster than those of air and vacuum dried beads in the first 90 min. The present results illustrate the potential to protect GLS by encapsulation using electrospraying to achieve the controlled release of GLS ingredients. This will pave the way to develop effective GLS products with desirable bioactive components for healthcare applications.

  4. Bioactive apatite incorporated alginate microspheres with sustained drug-delivery for bone regeneration application.

    PubMed

    Li, Haibin; Jiang, Fei; Ye, Song; Wu, Yingying; Zhu, Kaiping; Wang, Deping

    2016-05-01

    The strontium-substituted hydroxyapatite microspheres (SrHA) incorporated alginate composite microspheres (SrHA/Alginate) were prepared via adding SrHA/alginate suspension dropwise into calcium chloride solution, in which the gel beads were formed by means of crosslinking reaction. The structure, morphology and in vitro bioactivity of the composite microspheres were studied by using XRD, SEM and EDS methods. The biological behaviors were characterized and analyzed through inductively coupled plasma optical emission spectroscopy (ICP-OES), CCK-8, confocal laser microscope and ALP activity evaluations. The experimental results indicated that the synthetic SrHA/Alginate showed similar morphology to the well-known alginate microspheres (Alginate) and both of them possessed a great in vitro bioactivity. Compared with the control Alginate, the SrHA/Alginate enhanced MC3T3-E1 cell proliferation and ALP activity by releasing osteoinductive and osteogenic Sr ions. Furthermore, vancomycin was used as a model drug to investigate the drug release behaviors of the SrHA/Alginate, Alginate and SrHA. The results suggested that the SrHA/Alginate had a highest drug-loading efficiency and best controlled drug release properties. Additionally, the SrHA/Alginate was demonstrated to be pH-sensitive as well. The increase of the pH value in phosphate buffer solution (PBS) accelerated the vancomycin release. Accordingly, the multifunctional SrHA/Alginate can be applied in the field of bioactive drug carriers and bone filling materials.

  5. Alginate-based ferrofluid and magnetic microsphere thereof.

    PubMed

    Xu, Peihu; Guo, Fengfeng; Huang, Jin; Zhou, Shaofeng; Wang, Daxin; Yu, Jiahui; Chen, Jinghua

    2010-12-01

    The Fe(3)O(4) ferrofluids have been prepared using sodium alginate (Na-AL) as a stabilizing agent. The alginate can prevent the aggregation of magnetic nanoparticles and hence contributed to higher stability for the ferrofluids. Furthermore, the alginate component in the ferrofluids was crosslinked by Ca(2+) to produce magnetic microspheres. The swelling behavior of magnetic microspheres showed a pH-dependence, and hence determined the drug release process under various pH conditions. The presence of the Fe(3)O(4) nanoparticles made the magnetic microspheres swell more easily. Meanwhile, the strong ability to absorb the drug for the incorporated Fe(3)O(4) nanoparticles decreased the release rate and hence was more favorable to the sustaining release of drug. Except for the controlled delivery and release of drug, the alginate-based ferrofluids and magnetic microspheres in this work might also show a great potential for other biomedical and biotechnological applications, such as, magnetic targeting, magnetic separation and magnetic resonance imaging.

  6. Characterization of holmium loaded alginate microspheres for multimodality imaging and therapeutic applications.

    PubMed

    Zielhuis, S W; Seppenwoolde, J H; Bakker, C J G; Jahnz, U; Zonnenberg, B A; van het Schip, A D; Hennink, W E; Nijsen, J F W

    2007-09-15

    In this paper the preparation and characterization of holmium-loaded alginate microspheres is described. The rapid development of medical imaging techniques offers new opportunities for the visualisation of (drug-loaded) microparticles. Therefore, suitable imaging agents have to be incorporated into these particles. For this reason, the element holmium was used in this study in order to utilize its unique imaging characteristics. The paramagnetic behaviour of this element allows visualisation with MRI and holmium can also be neutron-activated resulting in the emission of gamma-radiation, allowing visualisation with gamma cameras, and beta-radiation, suitable for therapeutic applications. Almost monodisperse alginate microspheres were obtained by JetCutter technology where alginate droplets of a uniform size were hardened in an aqueous holmium chloride solution. Ho(3+) binds via electrostatic interactions to the carboxylate groups of the alginate polymer and as a result alginate microspheres loaded with holmium were obtained. The microspheres had a mean size of 159 microm and a holmium loading of 1.3 +/- 0.1% (w/w) (corresponding with a holmium content based on dry alginate of 18.3 +/- 0.3% (w/w)). The binding capacity of the alginate polymer for Ho(3+) (expressed in molar amounts) is equal to that for Ca(2+), which is commonly used for the hardening of alginate. This indicates that Ho(3+) has the same binding affinity as Ca(2+). In line herewith, dynamic mechanical analyses demonstrated that alginate gels hardened with Ca(2+) or Ho(3+) had similar viscoelastic properties. The MRI relaxation properties of the microspheres were determined by a MRI phantom experiment, demonstrating a strong R(2)* effect of the particles. Alginate microspheres could also be labelled with radioactive holmium by adding holmium-166 to alginate microspheres, previously hardened with calcium (labelling efficiency 96%). The labelled microspheres had a high radiochemical stability (94% after

  7. EVALUATION OF ALGINATE MICROSPHERES WITH METRONIDAZOLE OBTAINED BY THE SPRAY DRYING TECHNIQUE.

    PubMed

    Szekalska, Marta; Winnicka, Katarzyna; Czajkowska-Kośnik, Anna; Sosnowska, Katarzyna; Amelian, Aleksandra

    2015-01-01

    In the present study, nine formulations (F1-F9) of alginate microspheres with metronidazole were prepared by the spray drying technique with using different drug:polymer ratio (1:2, 1:1, 2:1) and different sodium alginate concentration (1, 2, 3%). The obtained microspheres were characterized for size, morphology, drug loading, (potential and swelling degree. Mucoadhesive properties were examined using texture analyzer and three different models of adhesive layers--gelatin discs, mucin gel and porcine vaginal mucosa. In vitro drug release, mathematical release profile and physical state of microspheres were also evaluated. The obtained results indicate that sodium alginate is a suitable polymer for developing mucoadhesive dosage forms of metronidazole. The optimal formulation F3 (drug:polymer ratio 1:2 and 1% alginate solution) was characterized by the highest metronidazole loading and sustained drug release. The results of this study indicate promising potential of ALG microspheres as alternative dosage forms for metronidazole delivery.

  8. Preparation methods of alginate nanoparticles.

    PubMed

    Paques, Jerome P; van der Linden, Erik; van Rijn, Cees J M; Sagis, Leonard M C

    2014-07-01

    This article reviews available methods for the formation of alginate nano-aggregates, nanocapsules and nanospheres. Primarily, alginate nanoparticles are being prepared by two methods. In the "complexation method", complex formation on the interface of an oil droplet is used to form alginate nanocapsules, and complex formation in an aqueous solution is used to form alginate nano-aggregates. In a second method w/o emulsification coupled with gelation of the alginate emulsion droplet can be used to form alginate nanospheres. We review advantages and disadvantages of these methods, and give an overview of the properties of the alginate particles produced with these methods.

  9. Laser-assisted fabrication of highly viscous alginate microsphere

    NASA Astrophysics Data System (ADS)

    Lin, Yafu; Huang, Yong

    2011-04-01

    Encapsulated microspheres have been widely used in various biomedical applications. However, fabrication of encapsulated microspheres from highly viscous materials has always been a manufacturing challenge. The objective of this study is to explore a novel metallic foil-assisted laser-induced forward transfer (LIFT), a laser-assisted fabrication technique, to make encapsulated microspheres using high sodium alginate concentration solutions. The proposed four-layer approach includes a quartz disk, a sacrificial and adhesive layer, a metallic foil, and a transferred suspension layer. It is found that the proposed four-layer modified LIFT approach provides a promising fabrication technology for making of bead-encapsulated microspheres from highly viscous solutions. During the process, the microsphere only can be formed if the direct-writing height is larger than the critical direct-writing height; otherwise, tail structured droplets are formed; and the encapsulated microsphere diameter linearly increases with the laser fluence and decreases with the sodium alginate concentration.

  10. Two new plate nozzles for the production of alginate microspheres.

    PubMed

    Yang, Fan; Wang, Kang; He, Zhimin

    2005-07-14

    Combining the Rayleigh-type jet break-up and two new plate nozzles, the alginate microsphere was produced. Spray generators made of syringe needle and laser-drilling nozzle plate and synthetic red stone nozzle plate were fabricated and contrasted. The above two plate nozzles provided lower liquid resistance and yield well. Furthermore, the more uniform microsphere was produced within a wider range of frequency by plate nozzles. Experiments using multiple-nozzle synthetic red stone plate was easy to feasible.

  11. Biodegradable alginate microspheres as a delivery system for naked DNA.

    PubMed Central

    Aggarwal, N; HogenEsch, H; Guo, P; North, A; Suckow, M; Mittal, S K

    1999-01-01

    Sodium alginate is a naturally occurring polysaccharide that can easily be polymerized into a solid matrix to form microspheres. These biodegradable microspheres were used to encapsulate plasmid DNA containing the bacterial beta-galactosidase (LacZ) gene under the control of either the cytomegalovirus (CMV) immediate-early promoter or the Rous sarcoma virus (RSV) early promoter. Mice inoculated orally with microspheres containing plasmid DNA expressed LacZ in the intestine, spleen and liver. Inoculation of mice with microspheres containing both the plasmid DNA and bovine adenovirus type 3 (BAd3) resulted in a significant increase in LacZ expression compared to those inoculated with microspheres containing only the plasmid DNA. Our results suggest that adenoviruses are capable of augumenting transgene expression by plasmid DNA both in vitro and in vivo. Images Figure 3. PMID:10369574

  12. [Comparison of rheologic properties between Ca-alginate hydrogel microspheres suspension and whole blood].

    PubMed

    Xu, Pei; Wang, Xiang; Li, Yaojin; Wang, Feifei; Duan, Ming; Yang, Li

    2013-02-01

    Starting from the form of red blood cells and the hematocrit (Hct, about 45 vol% of whole blood), we tried to prepare a kind of microspheres suspension to imitate non-Newtonian fluid property of whole blood, exploring its potentiality to be applied in blood viscosity quality control substance. In our study, we produced Ca-alginate hydrogel microspheres using emulsion polymerization, then we suspended the microspheres in 0.9 wt% NaCl solution to obtain a kind of liquid sample with the microspheres taking 45% volume. Then we used two types of viscometers to measure and analyse the changes of sample viscosity at different shear rate. We observed the forms of Ca-alginate hydrogel microspheres with microscope, and found them to be relatively complete, and their diameters to be normally distributed. Diameters of about 90% of the microspheres were distributed in a range from 6 to 22 micron. The samples were examined with viscometer FASCO-3010 and LG-R-80c respectively, both of which have shown a shear-thinning effect. After 5-week stability test, the CV of viscosity results corresponding to the two instruments were 7.3% to 13.8% and 8.9% to 14.2%, respectively. Although some differences existed among the results under the same shear rate, the general variation trends of the corresponding results were consistent, so the sample had the potentiality to be widely used in calibrating a different type of blood viscometer.

  13. Kefiran-alginate gel microspheres for oral delivery of ciprofloxacin.

    PubMed

    Blandón, Lina M; Islan, German A; Castro, Guillermo R; Noseda, Miguel D; Thomaz-Soccol, Vanete; Soccol, Carlos R

    2016-09-01

    Ciprofloxacin is a broad-spectrum antibiotic associated with gastric and intestinal side effects after extended oral administration. Alginate is a biopolymer commonly employed in gel synthesis by ionotropic gelation, but unstable in the presence of biological metal-chelating compounds and/or under dried conditions. Kefiran is a microbial biopolymer able to form gels with the advantage of displaying antimicrobial activity. In the present study, kefiran-alginate gel microspheres were developed to encapsulate ciprofloxacin for antimicrobial controlled release and enhanced bactericidal effect against common pathogens. Scanning electron microscopy (SEM) analysis of the hybrid gel microspheres showed a spherical structure with a smoother surface compared to alginate gel matrices. In vitro release of ciprofloxacin from kefiran-alginate microspheres was less than 3.0% and 5.0% at pH 1.2 (stomach), and 5.0% and 25.0% at pH 7.4 (intestine) in 3 and 21h, respectively. Fourier transform infrared spectroscopy (FTIR) of ciprofloxacin-kefiran showed the displacement of typical bands of ciprofloxacin and kefiran, suggesting a cooperative interaction by hydrogen bridges between both molecules. Additionally, the thermal analysis of ciprofloxacin-kefiran showed a protective effect of the biopolymer against ciprofloxacin degradation at high temperatures. Finally, antimicrobial assays of Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Salmonella typhymurium, and Staphylococcus aureus demonstrated the synergic effect between ciprofloxacin and kefiran against the tested microorganisms.

  14. In-vivo evaluation of clindamycin release from glyceryl monooleate-alginate microspheres by NIR spectroscopy.

    PubMed

    Mohamed, Amir Ibrahim; Ahmed, Osama A A; Amin, Suzan; Elkadi, Omar Anwar; Kassem, Mohamed A

    2015-10-15

    The purpose of this study was to use near-infrared (NIR) transmission spectroscopic technique to determine clindamycin plasma concentration after oral administration of clindamycin loaded GMO-alginate microspheres using rabbits as animal models. Lyophilized clindamycin-plasma standard samples at a concentration range of 0.001-10 μg/ml were prepared and analyzed by NIR and HPLC as a reference method. NIR calibration model was developed with partial least square (PLS) regression analysis. Then, a single dose in-vivo evaluation was carried out and clindamycin-plasma concentration was estimated by NIR. Over 24 h time period, the pharmacokinetic parameters of clindamycin were calculated for the clindamycin loaded GMO-alginate microspheres (F3) and alginate microspheres (F2), and compared with the plain drug (F1). PLS calibration model with 7-principal components (PC), and 8000-9200 cm(-1) spectral range shows a good correlation between HPLC and NIR values with root mean square error of cross validation (RMSECV), root mean square error of prediction (RMSEP), and calibration coefficient (R(2)) values of 0.245, 1.164, and 0.9753, respectively, which suggests that NIR transmission technique can be used for drug-plasma analysis without any extraction procedure. F3 microspheres exhibited controlled and prolonged absorption Tmax of 4.0 vs. 1.0 and 0.5 h; Cmax of 2.37±0.3 vs. 3.81±0.8 and 5.43±0.7 μg/ml for F2 and F1, respectively. These results suggest that the combination of GMO and alginate (1:4 w/w) could be successfully employed for once daily clindamycin microspheres formulation which confirmed by low Cmax and high Tmax values.

  15. Novel Alginate-Chitosan Composite Microspheres for Implant Delivery of Vancomycin and In Vivo Evaluation.

    PubMed

    Mao, Yimin; Zhao, Ming; Ge, Yongbiao; Fan, Jiang

    2016-09-01

    In this study, vancomycin loaded alginate-chitosan composite microspheres were developed by emulsion cross-linking method. The in vitro and vivo characterizations were done to evaluate the feasibility of application. Our experimental results showed that the emulsification cross-linking technique appeared to be a feasible method for the preparation of alginate-chitosan composite microspheres. The microspheres were spherical in shape and the mean particle size and drug loading were 25.3 ± 5.4 μm and 18.5 ± 2.3% respectively. A sustained vancomycin release was realized i.e. the amount of cumulative release increased in a time frame of 24 h to reach an amount i.e. ~68%. The model that fit best for vancomycin released from the microspheres was the Higuchi kinetic model with a correlation coefficient r = 0.9996. In vivo results showed that the application of microspheres not only reduced the toxicity, but also maintained effective drug concentration. In addition, no severe signs of epithelial necrosis and sloughing of epithelial cells were detected in histological studies.

  16. Holmium-lipiodol-alginate microspheres for fluoroscopy-guided embolotherapy and multimodality imaging.

    PubMed

    Oerlemans, Chris; Seevinck, Peter R; Smits, Maarten L; Hennink, Wim E; Bakker, Chris J G; van den Bosch, Maurice A A J; Nijsen, J Frank W

    2015-03-30

    Embolotherapy is a minimally invasive transcatheter technique aiming at reduction or complete obstruction of the blood flow by infusion of micro-sized particles in order to induce tumor regression. A major drawback of the current commercially available and clinically used microspheres is that they cannot be detected in vivo with medical imaging techniques, impeding intra- and post-procedural feedback. It can be expected that real-time monitoring of microsphere infusion and post-procedural imaging will result in better predictability and higher efficacy of the treatment. In this study, a novel microsphere formulation has been developed that can be visualized with fluoroscopy, X-ray computed tomography (CT) and magnetic resonance imaging (MRI). The microspheres were prepared with the JetCutter technique and consist of alginate (matrix-forming polymer), holmium (cross-linking and MRI contrast agent), lipiodol (radiopaque contrast agent) and Pluronic F-68 (surfactant). The mean size (±SEM) of the hydrated holmium-lipiodol-alginate microspheres (Ho-lip-ams) was 570±12 μm with a holmium content of 0.38±0.01% (w/w). Stability studies showed that the microspheres remained intact during incubation for two weeks in fetal calf serum (FCS) at 37 °C. The inclusion of lipiodol in the microspheres rendered excellent visualization capabilities for fluoroscopy and CT, whereas the holmium ions, which keep the alginate network together, also allow MR imaging. In this study it was shown that single sphere detection was possible by fluoroscopy, CT and MRI. The Ho-lip-ams were visualized in real-time, during infusion in a porcine kidney using fluoroscopy, and post-procedural, the deposition of the microspheres was examined with fluoroscopy, (cone beam rotational) CT and MRI. The different imaging modalities showed similar deposition patterns of the microspheres within the organ. The combination of intra-procedural visualization, multimodality imaging for patient follow-up and the

  17. Method for preparing hollow metal oxide microsphere

    DOEpatents

    Schmitt, C.R.

    1974-02-12

    Hollow refractory metal oxide microspheres are prepared by impregnating resinous microspheres with a metallic compound, drying the impregnated microspheres, heating the microspheres slowly to carbonize the resin, and igniting the microspheres to remove the carbon and to produce the metal oxide. Zirconium oxide is given as an example. (Official Gazette)

  18. Immunization Against Cutaneous Leishmaniasis by Alginate Microspheres Loaded With Autoclaved Leishmania Major (ALM) and Quillaja Saponins.

    PubMed

    Tafaghodi, Mohsen; Eskandari, Maryam; Khamesipour, Ali; Jaafari, Mahmoud Reza

    2016-01-01

    Leishmania antigens are weak immunogens and need to be potentiated by various adjuvants and delivery systems. Alginate microspheres as antigen delivery system and Quillaja saponins (QS) as immunoadjuvant have been used to enhance the immune response against Autoclaved Leishmania major (ALM). Microspheres were prepared by an emulsification technique and characterized for size, encapsulation efficiency and release profile of encapsulates. BALB/c mice were immunized three times in 3-weeks intervals using ALM plus QS loaded microspheres [(ALM+QS)ALG], ALM encapsulated with alginate microspheres [(ALM)ALG], (ALM)ALG + QS, ALM + QS, ALM alone or PBS. The intensity of infection induced by L. major challenge was assessed by measuring size of footpad swelling. The strongest protection, showed by significantly (P < 0.05) smaller footpad, were observed in mice immunized with (ALM)ALG+QS. The (ALM+QS)ALG, ALM and PBS groups showed the least protection and highest swelling, while the (ALM)ALG and ALM+QS showed an intermediate protection with no significant difference. The mice immunized with (ALM+QS)ALG showed the highest IgG2a/IgG1 ratio (P<0.05). The highest IFN-γ and IL-4 production was seen in ALM+QS (P<0.01). It is concluded that QS adjuvant has a mixed Th1/Th2 effect and has increased both humoral and cellular immune responses.

  19. Metal ion-induced alginate-locust bean gum IPN microspheres for sustained oral delivery of aceclofenac.

    PubMed

    Jana, Sougata; Gandhi, Arijit; Sheet, Subrata; Sen, Kalyan Kumar

    2015-01-01

    The alginate microspheres represent a useful tool for sustained oral delivery of drugs but exhibit several problems associated with the stability and rapid release of drugs at higher pH values. To overcome these drawbacks, alginate-locust bean gum (LBG) interpenetrating microspheres were prepared by calcium ion (Ca(+2)) induced ionotropic gelation technique for prolonged release of aceclofenac. The drug entrapment efficiency of these microspheres was found to be 59-93%. The microspheres lied in the size range of 406-684μm. Scanning electron microscopy revealed spherical shape of the microspheres. No drug-polymer interaction was evident after infrared spectroscopy analysis. The microspheres provided sustained release of aceclofenac in phosphate buffer solution (pH 6.8) over a period of 8h. The drug release data were fitted into the Korsmeyer-Peppas model and the drug release was found to follow anomalous (non-Fickian) diffusion mechanism. Pharmacodynamic study of the microspheres showed a prolonged anti-inflammatory activity in carrageenan-induced rat paw model following oral administration.

  20. Microspheres of carboxymethyl chitosan, sodium alginate and collagen for a novel hemostatic in vitro study.

    PubMed

    Shi, Xinyi; Fang, Qiang; Ding, Miao; Wu, Jing; Ye, Fei; Lv, Zhengbing; Jin, Jia

    2016-02-01

    To develop biocompatible composite microspheres for novel hemostatic use, we designed and prepared a novel biomaterial, composite microspheres consisting of carboxymethyl chitosan, sodium alginate, and collagen (CSCM). The ultra-structure of CSCM was investigated by scanning electron microscopy assay. In hemostatic function experiment, it was found that CSCM could facilitate platelet adherence, platelet aggregation, and platelet activation in vitro. Besides, the maximum swelling of CSCM submerged in PBS for 50 min was over 300% of that exhibited by commercial hemostatic compound microporous polysaccharide haemostatic powder (CMPHP). In addition, CSCM exhibited good biodegradability and non-cytotoxicity. These results demonstrated that CSCM may be useful in platelet plug formation, and this study would provide important information for further research on hemostasis experiment in vivo.

  1. Microfluidic one-step synthesis of alginate microspheres immobilized with antibodies

    PubMed Central

    Chen, Wanyu; Kim, Jong-Hoon; Zhang, Di; Lee, Kyong-Hoon; Cangelosi, G. A.; Soelberg, S. D.; Furlong, C. E.; Chung, Jae-Hyun; Shen, Amy Q.

    2013-01-01

    Micrometre- and submicrometre-size functionalized beads are frequently used to capture targets of interest from a biological sample for biological characterizations and disease diagnosis. The main challenge of the microbead-based assay is in the immobilization of probe molecules onto the microbead surfaces. In this paper, we report a versatile droplet microfluidics method to fabricate alginate microspheres while simultaneously immobilizing anti-Mycobacterium tuberculosis complex IgY and anti-Escherichia coli IgG antibodies primarily on the porous alginate carriers for specific binding and binding affinity tests. The binding affinity of antibodies is directly measured by fluorescence intensity of stained target bacteria on the microspheres. We demonstrate that the functionalized alginate microspheres yield specificity comparable with an enzyme-linked immunosorbent assay. The high surface area-to-volume ratio of the functionalized porous alginate microspheres improves the detection limit. By using the droplet microfluidics, we can easily modify the size and shape of alginate microspheres, and increase the concentration of functionalized alginate microspheres to further enhance binding kinetics and enable multiplexing. PMID:23966617

  2. Gastroretentive drug delivery system of acyclovir-loaded alginate mucoadhesive microspheres: formulation and evaluation.

    PubMed

    Shadab; Ahuja, Alka; Khar, Roop K; Baboota, Sanjula; Chuttani, Krishna; Mishra, A K; Ali, Javed

    2011-05-01

    In the present study, mucoadhesive alginate microspheres of acyclovir were prepared to prolong the gastric residence time using a simple emulsification phase separation technique. The particle size of drug-loaded formulations was measured by SEM and the particle size distribution was determined using an optical microscope and mastersizer. The release profile of acyclovir from microspheres was examined in simulated gastric fluid (SGF pH 1.2). The particles were found to be discreet and spherical with the maximum particles of an average size (70.60 ± 2.44 µm). The results indicated that the mean particle size of the microspheres increased with an increase in the concentration of polymer and decreased with increase in stirring speed. The entrapment efficiency was found to be in the range of 51.42-80.46%. The concentration of the calcium chloride (% w/v) of 10% and drug-polymer ratio of 1:4 resulted in an increase in the entrapment efficiency and the extent of drug release. The optimized alginate microspheres were found to possess good mucoadhesion (66.42 ± 1.01%). The best fit model with the highest regression coefficient values (R²) was predicted by Peppas model (0.9813). In Gamma scintigraphy analysis, the section of GIT was critically analyzed and much differentiation was present at each time point after oral administration, which revealed that the optimized formulation demonstrated gastroretention in vivo for more than 4 h, which revealed that optimized formulation could be a good choice for gastroretentive systems.

  3. Alginate Microsphere Fabrication Using Bipolar Wave-Based Drop-on-Demand Jetting

    PubMed Central

    Herran, C. Leigh; Huang, Yong

    2012-01-01

    Scale-up microsphere fabrication with controllable microsphere size has always been an exciting manufacturing challenge. The objective of this study is to experimentally study the effects of material properties and operating conditions on the formability of alginate microspheres and the microsphere size during drop-on-demand (DOD)-based single nozzle jetting. Alginate microspheres have been fabricated using bipolar wave-based drop-on-demand jetting, and its formability and size have been studied especially as a function of sodium alginate and calcium chloride concentrations, voltage rise/fall times, dwell and echo times, excitation voltage amplitudes, and frequency. It is found that 1) the formability is sensitive to the sodium alginate and calcium chloride concentrations, dwell and echo voltages, and voltage dwell time; and the formability decreases with the sodium alginate concentration but increases with the calcium chloride concentration, dwell and echo voltages, and voltage dwell time; 2) the size is not sensitive to the sodium alginate and calcium chloride concentrations but increases first with the dwell time and then decreases; and 3) the size increases with the dwell and absolute echo voltage amplitudes. PMID:22639550

  4. Gelling process of sodium alginate with bivalent ions rich microsphere: Nature of bivalent ions

    NASA Astrophysics Data System (ADS)

    Mauri, Marco; Vicini, Silvia; Castellano, Maila

    2016-05-01

    In the paper we present a new approach for obtaining a controlled gelling process of sodium alginate, based on the quantity of bivalent ions rich alginate micro-beads added as crosslinkers. Typically, calcium ions are used in gelation of alginate solutions. In this study we present different gelling systems realized with alginate microspheres, made by electrospinning methodology, enriched with different bivalent ions (Ca2+, Ba2+ and Mg2+). The microspheres were characterized under the point of view of the morphology by OM and as the ions content. Realized gels were characterized in light of the amount of the ions added to the alginate solution, and in light of the different dimensions of the micro-beads, using rheological measurements to assess the variation in the storage modulus (G'), loss modulus (G″) and complex viscosity (η*).

  5. Alginate Microspheres Containing Temperature Sensitive Liposomes (TSL) for MR-Guided Embolization and Triggered Release of Doxorubicin

    PubMed Central

    van Elk, Merel; Ozbakir, Burcin; Barten-Rijbroek, Angelique D.; Storm, Gert; Nijsen, Frank; Hennink, Wim E.; Vermonden, Tina; Deckers, Roel

    2015-01-01

    Objective The objective of this study was to develop and characterize alginate microspheres suitable for embolization with on-demand triggered doxorubicin (DOX) release and whereby the microspheres as well as the drug releasing process can be visualized in vivo using MRI. Methods and Findings For this purpose, barium crosslinked alginate microspheres were loaded with temperature sensitive liposomes (TSL/TSL-Ba-ms), which release their payload upon mild hyperthermia. These TSL contained DOX and [Gd(HPDO3A)(H2O)], a T1 MRI contrast agent, for real time visualization of the release. Empty alginate microspheres crosslinked with holmium ions (T2* MRI contrast agent, Ho-ms) were mixed with TSL-Ba-ms to allow microsphere visualization. TSL-Ba-ms and Ho-ms were prepared with a homemade spray device and sized by sieving. Encapsulation of TSL in barium crosslinked microspheres changed the triggered release properties only slightly: 95% of the loaded DOX was released from free TSL vs. 86% release for TSL-Ba-ms within 30 seconds in 50% FBS at 42°C. TSL-Ba-ms (76 ± 41 μm) and Ho-ms (64 ± 29 μm) had a comparable size, which most likely will result in a similar in vivo tissue distribution after an i.v. co-injection and therefore Ho-ms can be used as tracer for the TSL-Ba-ms. MR imaging of a TSL-Ba-ms and Ho-ms mixture (ratio 95:5) before and after hyperthermia allowed in vitro and in vivo visualization of microsphere deposition (T2*-weighted images) as well as temperature-triggered release (T1-weighted images). The [Gd(HPDO3A)(H2O)] release and clusters of microspheres containing holmium ions were visualized in a VX2 tumor model in a rabbit using MRI. Conclusions In conclusion, these TSL-Ba-ms and Ho-ms are promising systems for real-time, MR-guided embolization and triggered release of drugs in vivo. PMID:26561370

  6. A protein delivery system: biodegradable alginate-chitosan-poly(lactic-co-glycolic acid) composite microspheres.

    PubMed

    Zheng, Cai-Hong; Gao, Jian-Qing; Zhang, Ye-Ping; Liang, Wen-Quan

    2004-10-29

    In the present study we developed alginate-chitosan-poly(lactic-co-glycolic acid) (PLGA) composite microspheres to elevate protein entrapment efficiency and decrease its burst release. Bovine serum albumin (BSA), which used as the model protein, was entrapped into the alginate microcapsules by a modified emulsification method in an isopropyl alcohol-washed way. The rapid drug releases were sustained by chitosan coating. To obtain the desired release properties, the alginate-chitosan microcapsules were further incorporated in the PLGA to form the composite microspheres. The average diameter of the composite microcapsules was 31+/-9microm and the encapsulation efficiency was 81-87%, while that of conventional PLGA microspheres was just 61-65%. Furthermore, the burst releases at 1h of BSA entrapped in composite microspheres which containing PLGA (50:50) and PLGA (70:30) decreased to 24% and 8% in PBS, and further decreased to 5% and 2% in saline. On the contrary, the burst releases of conventional PLGA microspheres were 48% and 52% in PBS, respectively. Moreover, the release profiles could be manipulated by regulating the ratios of poly(lactic acid) to poly(glycolic acid) in the composite microspheres.

  7. Development of pH-sensitive pectinate/alginate microspheres for colon drug delivery.

    PubMed

    Hsu, Fu-Yin; Yu, Ding-Syuan; Huang, Chun-Chiang

    2013-02-01

    The purposes of this study were to develop and evaluate calcium pectinate/alginate microspheres (PAMs) and to exploit their pH-sensitive properties for colon-targeted delivery of encapsulated cisplatin. PAMs were prepared using an electrospraying method. The PAMs, as cores, were then coated with Eudragit S100 using a polyelectrolyte multilayer coating technique in aqueous solution. The morphology of the microspheres was observed under scanning electron microscopy. In vitro drug release studies were performed in simulated gastrointestinal fluid, and the results indicated that approximately 5 % of the cisplatin was released from the Eudragit S100-coated PAMs, and 51 % of the cisplatin was released from the uncoated PAMs at 1 h. The release of cisplatin from the Eudragit S100-coated PAMs was more sustained in simulated gastric fluid than in simulated intestinal fluid due to the increased solubility of the coating polymer in media with pH >7.0. Drug release from the Eudragit S100-coated PAMs was best described by the Higuchi's square root model. From these results, it was concluded that Eudragit S100-coated PAMs are a potential carrier for delivery of cisplatin to the colon.

  8. Dual-Crosslinked Methacrylated Alginate Sub-Microspheres for Intracellular Chemotherapeutic Delivery

    PubMed Central

    Scherrer, Ryan M.; Oldinski, Rachael A.

    2016-01-01

    Intracellular delivery vehicles comprised of methacrylated alginate (Alg-MA) were developed for the internalization and release of doxorubicin hydrochloride (DOX). Alg-MA was synthesized via an anhydrous reaction, and a mixture of Alg-MA and DOX was formed into sub-microspheres using a water/oil emulsion. Covalently crosslinked sub-microspheres were formed via exposure to green light, in order to investigate effects of crosslinking on drug release and cell internalization, compared to traditional techniques such as ultra violet (UV) light. Crosslinking was performed using light exposure alone, or in combination with ionic crosslinking using calcium chloride (CaCl2). Alg-MA sub-microsphere diameters were between 88 – 617 nm, and zeta-potentials were between −20 and −37 mV. Using human lung epithelial carcinoma cells (A549s) as a model, cellular internalization was confirmed using flow cytometry; different sub-microsphere formulations varied the efficiency of internalization, with UV-crosslinked sub-microspheres achieving the highest internalization percentages. While blank (non-loaded) Alg-MA sub-microspheres were non-cytotoxic to A549s, DOX-loaded sub-microspheres significantly reduced mitochondrial activity after five days of culture. Photo-crosslinked Alg-MA sub-microspheres may be a potential chemotherapeutic delivery system for cancer treatment. PMID:27378419

  9. Carboxymethyl starch/alginate microspheres containing diamine oxidase for intestinal targeting

    PubMed Central

    Blemur, Lindsay; Le, Tien Canh; Marcocci, Lucia; Pietrangeli, Paola

    2015-01-01

    Abstract The association of carboxymethyl starch (CMS) and alginate is proposed as a novel matrix for the entrapment of bioactive agents in microspheres affording their protection against gastrointestinal degradation. In this study, the enzyme diamine oxidase (DAO) from white pea (Lathyrus sativus) was immobilized by inclusion in microspheres formed by ionotropic gelation of CMS/alginate by complexation with Ca2+. The association of CMS to alginate generated a more compact structure presenting a lesser porosity, thus decreasing the access of gastric fluid inside the microspheres and preventing the loss of entrapped enzyme. Moreover, the immobilized enzyme remained active and was able to oxidize the polyamine substrates even in the presence of degrading proteases of pancreatin. The inclusion yield in terms of entrapped protein was of about 82%–95%. The DAO entrapped in calcium CMS/alginate beads retained up to 70% of its initial activity in simulated gastric fluid (pH 2.0). In simulated intestinal fluid (pH 7.2) with pancreatin, an overall retention of 65% of activity for the immobilized DAO was observed over 24 H, whereas in similar conditions the free enzyme was totally inactivated. Our project proposes the vegetal DAO as an antihistaminic agent orally administered to treat food histaminosis and colon inflammation. PMID:25779356

  10. Carboxymethyl starch/alginate microspheres containing diamine oxidase for intestinal targeting.

    PubMed

    Blemur, Lindsay; Le, Tien Canh; Marcocci, Lucia; Pietrangeli, Paola; Mateescu, Mircea Alexandru

    2016-05-01

    The association of carboxymethyl starch (CMS) and alginate is proposed as a novel matrix for the entrapment of bioactive agents in microspheres affording their protection against gastrointestinal degradation. In this study, the enzyme diamine oxidase (DAO) from white pea (Lathyrus sativus) was immobilized by inclusion in microspheres formed by ionotropic gelation of CMS/alginate by complexation with Ca(2+) . The association of CMS to alginate generated a more compact structure presenting a lesser porosity, thus decreasing the access of gastric fluid inside the microspheres and preventing the loss of entrapped enzyme. Moreover, the immobilized enzyme remained active and was able to oxidize the polyamine substrates even in the presence of degrading proteases of pancreatin. The inclusion yield in terms of entrapped protein was of about 82%-95%. The DAO entrapped in calcium CMS/alginate beads retained up to 70% of its initial activity in simulated gastric fluid (pH 2.0). In simulated intestinal fluid (pH 7.2) with pancreatin, an overall retention of 65% of activity for the immobilized DAO was observed over 24 H, whereas in similar conditions the free enzyme was totally inactivated. Our project proposes the vegetal DAO as an antihistaminic agent orally administered to treat food histaminosis and colon inflammation.

  11. Development of alginate microspheres containing thyme essential oil using ionic gelation.

    PubMed

    Benavides, Sergio; Cortés, Pablo; Parada, Javier; Franco, Wendy

    2016-08-01

    Essential oils are a good antimicrobial and antioxidant agent alternative in human or animal feed. However, their direct use has several disadvantages such as volatilization or oxidation. The development of essential oil microspheres may help to avoid these problems. The objective of the present research was to microencapsulate thyme essential oil by generating emulsions with different dispersion degrees. The emulsions were encapsulated in calcium-alginate microspheres by ionic gelation. The microspheres were evaluated regarding size, shape, encapsulation efficiency, loading capacity and antimicrobial properties. The results indicate that encapsulation efficiency and loading capacity are dependent on concentration and degree of dispersion. The best encapsulation conditions were obtained at 2% v/v of thyme essential oil with a high dispersion degree (18,000rpm/5min), which was achieved with an efficiency of 85%. Finally, the microspheres obtained showed significant antimicrobial effect, especially in gram-positive bacteria.

  12. Intra-articular Administration of Chitosan Thermosensitive In Situ Hydrogels Combined With Diclofenac Sodium-Loaded Alginate Microspheres.

    PubMed

    Qi, Xiaole; Qin, Xiaoxue; Yang, Rong; Qin, Jiayi; Li, Wenyan; Luan, Kun; Wu, Zhenghong; Song, Li

    2016-01-01

    The aims of this study were to prepare fine intra-articular-administrated chitosan thermosensitive hydrogels combined with alginate microspheres and to investigate the possibility of those hydrogels as a drug delivery system for promoting the anti-inflammation effect. Diclofenac sodium containing alginate microspheres was prepared by a modified emulsification and/or gelation method and then dispersed into injectable thermosensitive hydrogels, consisting of chitosan and β-glycerophosphate. The final combined hydrogels were evaluated in terms of their morphology properties, rheological properties, in vitro drug release, and in vivo biocompatibility and pharmacodynamics behaviors. The optimized formulation exhibited sol-gel transition at 31.72 ± 0.42°C and quickly turned into gel within 5 min, with sustained drug release characteristics followed Ritger-Peppas equation, which could prolong the in vitro drug release to 5 days. In addition, the anti-inflammation efficacy of the combined hydrogels in rabbits with experimental rheumatoid arthritis was higher than that of drug solution and pure chitosan hydrogels. Those results demonstrated that these combined hydrogels could become a potential drug delivery system for improving the therapeutic effect of diclofenac sodium and suggested an important technology platform for intra-articular administration.

  13. [Preparation of cinnamomi cortex oil microspheres based on porous silicon dioxide and its property characterizations].

    PubMed

    Zhu, Chun-Xia; Jiang, Yan-Rong; Zhang, Zhen-Hai; Ding, Dong-Mei; Jia, Xiao-Bin

    2013-10-01

    To determine the optimum process for preparing Cinnamomi Cortex oil microspheres based on porous silicon dioxide. After porous silica dioxide adsorbed Cinnamomi Cortex oil, Cinnamomi Cortex oil microspheres were prepared by the dropping method, with sodium alginate as the skeleton materials. The preparation process was optimized through the L(9) (3(4)) orthogonal test design, with microspheres diameter, distribution, drug loading capacity and entrapment efficiency as the indexes. The cinnamon volatile oil microspheres were characterized by scanning election microscope (SEM), thermogravimetric analysis (TGA), and infrared (IR) spectroscopy. An in vitro drug release experiment was conducted. The results showed that the microspheres prepared with the optimal process parameters were in good shape, even in size and good in dispersibility, with an average diameter of 1.61 mm, an average drug loading capacity of 32.85%, an entrapment efficiency of 94.79%. The maximum drug release capacity reached 72.6%, 95.0%, 97.4%, respectively, under pH 4.0, 6.8, 7.4 in 6 hours. Meanwhile, microsphere generation was tested by IR, TGA and other methods. The established optimum process for preparing Cinnamomi Cortex oil microspheres was proved to be stable and practical.

  14. Covalently antibacterial alginate-chitosan hydrogel dressing integrated gelatin microspheres containing tetracycline hydrochloride for wound healing.

    PubMed

    Chen, Huinan; Xing, Xiaodong; Tan, Huaping; Jia, Yang; Zhou, Tianle; Chen, Yong; Ling, Zhonghua; Hu, Xiaohong

    2017-01-01

    An antibacterial and biodegradable composite hydrogel dressing integrated with microspheres is developed for drug delivery and wound healing. The mechanism of gelation is attributed to the Schiff-base reaction between aldehyde and amino groups of oxidized alginate (OAlg) and carboxymethyl chitosan (CMCS). To enhance antibacterial and mechanical properties, tetracycline hydrochloride (TH) loaded gelatin microspheres (GMs) were fabricated by an emulsion cross-linking method, followed by integrating into the OAlg-CMCS hydrogel to produce a composite gel dressing. In vitro gelation time, swelling, degradation, compressive modulus and rheological properties of the gel dressing were investigated as the function of microsphere ratios. With increasing ratios of microspheres from 10 to 40mg/mL, the composite dressing manifested shorter gelation time and lower swelling ratios, as well as higher mechanical strength. Comparing to other formulations, the gel dressing with 30mg/mL microspheres showed more suitable stabilities and mechanical properties for wound healing. Also, in vitro drug release results showed that the loaded TH could be sustained release from the composite gel dressing by contrast with pure hydrogels and microspheres. Furthermore, powerful bacteria growth inhibition effects against Escherichia coli and Staphylococcus aureus suggested that the composite gel dressing, especially the one with 30mg/mL GMs containing TH, has a promising future in treatment of bacterial infection.

  15. Synthesis and characterisation of multifunctional alginate microspheres via the in situ formation of ZnO quantum dots and the graft of 4-(1-pyrenyl) butyric acid to sodium alginate.

    PubMed

    Luo, Guilin; Wang, Jianxin; Wang, Yingying; Feng, Bo; Weng, Jie

    2015-01-01

    Growth factor-loaded fluorescent alginate microspheres, which can realise sustained growth factor release and fluorescence imaging, were synthesised by in situ formation of ZnO quantum dots (QDs) and covalent graft of 4-(1-pyrenyl) butyric acid (PBA). BSA was chosen as a growth factor model protein to study the release kinetic of growth factors from alginate microspheres. The microsphere size and fluorescent properties were also investigated. Investigations of cell culture were used for evaluating biocompatibility of BSA-loaded fluorescent microspheres and fluorescence imaging property of ZnO QDs and PBA-grafted sodium alginate from the microspheres. The results show that they have good fluorescent property either to microspheres or to cells and fluorescent microspheres have good biocompatibility and property in sustained release of growth factors. The obtained microspheres will be expected to realise the imaging of cells and materials and also the release of growth factor in tissue engineering or in cell culture.

  16. Alginate/polyoxyethylene and alginate/gelatin hydrogels: preparation, characterization, and application in tissue engineering.

    PubMed

    Aroguz, Ayse Z; Baysal, Kemal; Adiguzel, Zelal; Baysal, Bahattin M

    2014-05-01

    Hydrogels are attractive biomaterials for three-dimensional cell culture and tissue engineering applications. The preparation of hydrogels using alginate and gelatin provides cross-linked hydrophilic polymers that can swell but do not dissolve in water. In this work, we first reinforced pure alginate by using polyoxyethylene as a supporting material. In an alginate/PEO sample that contains 20 % polyoxyethylene, we obtained a stable hydrogel for cell culture experiments. We also prepared a stable alginate/gelatin hydrogel by cross-linking a periodate-oxidized alginate with another functional component such as gelatin. The hydrogels were found to have a high fluid uptake. In this work, preparation, characterization, swelling, and surface properties of these scaffold materials were described. Lyophilized scaffolds obtained from hydrogels were used for cell viability experiments, and the results were presented in detail.

  17. Alginate microspheres encapsulated with autoclaved Leishmania major (ALM) and CpG-ODN induced partial protection and enhanced immune response against murine model of leishmaniasis.

    PubMed

    Tafaghodi, Mohsen; Eskandari, Maryam; Khamesipour, Ali; Jaafari, Mahmoud R

    2011-10-01

    A suitable adjuvant and delivery system are needed to enhance efficacy of vaccines against leishmaniasis. In this study, alginate microspheres as an antigen delivery system and CpG-ODN as an immunoadjuvant were used to enhance immune response and induce protection against an experimental autoclaved Leishmania major (ALM) vaccine. Alginate microspheres were prepared by an emulsification technique and the characteristics of the preparation such as size, encapsulation efficiency and release profile of encapsulates were studied. Mean diameter of microspheres was determined using SEM (Scanning Electron Microscopy) and particle size analyzer. The encapsulation efficiency was determined using Lowry protein assay method. The integrity of ALM antigens was assessed using SDS-PAGE. Mean diameter of microspheres was 1.8±1.0μm. BALB/c mice were immunized three times in 3-weeks intervals with ALM+CpG-ODN loaded microspheres [(ALM+CpG)(ALG)], ALM encapsulated alginate microspheres [(ALM)(ALG)], (ALM)(ALG)+CpG, ALM+CpG, ALM alone or PBS. The intensity of infection induced by L. major challenge was assessed by measuring size of footpad swelling. The strongest protection was observed in group of mice immunized with (ALM+CpG)(ALG). The groups of mice received (ALM+CpG)(ALG), (ALM)(ALG)+CpG, (ALM)(ALG) and ALM+CpG were also showed a significantly (P<0.05) smaller footpad swelling compared with the group that received either ALM alone or PBS. The mice immunized with (ALM+CpG)(ALG) or ALM+CpG showed the significantly (P<0.05) highest IgG2a/IgG1 ratio. The IFN-γ level was significantly (P<0.0001) highest in group of mice immunized with either (ALM)(ALG)+CpG or ALM+CpG. It is concluded that alginate microspheres and CpG-ODN adjuvant when are used simultaneously induced protection and enhanced immune response against ALM antigen.

  18. Hepatocytes cultured in alginate microspheres: an optimized technique to study enzyme induction.

    PubMed

    Ringel, M; von Mach, M A; Santos, R; Feilen, P J; Brulport, M; Hermes, M; Bauer, A W; Schormann, W; Tanner, B; Schön, M R; Oesch, F; Hengstler, J G

    2005-01-05

    An important application of hepatocyte cultures is identification of drugs acting as inducers of biotransformation enzymes that alter metabolic clearance of other therapeutic agents. In the present study we optimized an in vitro system with hepatocytes cultured in alginate microspheres that allow studies of enzyme induction with excellent sensitivity. Induction factors obtained with standard inducers, such as 3-methylcholanthrene or phenobarbital, were higher compared to those with conventional hepatocyte co-cultures on collagen coated dishes. This is illustrated by activities of 7-ethoxyresorufin-O-deethylase (EROD) after incubation with 5 microM 3-methylcholanthrene (3-MC), a standard inducer for cytochrome P4501A1 and 1A2. Mean activities for solvent controls and 3-MC exposed cells were 2.99 and 449 pmol/min/mg protein (induction factor: 150) for hepatocytes cultured in microspheres compared to 2.72 and 80.6 pmol/min/mg (induction factor: 29.6) for hepatocytes on collagen coated dishes. To compare these in vitro data to the in vivo situation male Sprague Dawley rats, the same strain that was used also for the in vitro studies, were exposed to 3-MC in vivo using a protocol that guarantees maximal induction. Activities were 29.2 and 1656 pmol/min/mg in liver homogenate of solvent and 3-MC treated animals (induction factor: 56.7). Thus, the absolute activities of 3-MC exposed hepatocytes in microspheres are lower compared to the in vivo situation. However, the induction factor in vitro was even higher compared to the in vivo situation (150-fold versus 56.7-fold). A similar scenario was observed using phenobarbital (0.75 mM) for induction of CYP2B and 3A isoenzymes: induction factors for testosterone hydroxylation in position 16beta were 127.5- and 50.4-fold for hepatocytes in microspheres and conventionally cultured hepatocytes, respectively. The new in vitro system with hepatocytes embedded in solid alginate microspheres offers several technical advantages: (i

  19. Preparation of small bio-compatible microspheres

    NASA Technical Reports Server (NTRS)

    Rembaum, Alan (Inventor); Yen, Shiao-Ping S. (Inventor); Dreyer, William J. (Inventor)

    1979-01-01

    Small, round, bio-compatible microspheres capable of covalently bonding proteins and having a uniform diameter below about 3500 A are prepared by substantially instantaneously initiating polymerization of an aqueous emulsion containing no more than 35% total monomer including an acrylic monomer substituted with a covalently bondable group such a hydroxyl, amino or carboxyl and a minor amount of a cross-linking agent.

  20. Preparation of in situ hardening composite microcarriers: calcium phosphate cement combined with alginate for bone regeneration.

    PubMed

    Park, Jung-Hui; Lee, Eun-Jung; Knowles, Jonathan C; Kim, Hae-Won

    2014-03-01

    Novel microcarriers consisting of calcium phosphate cement and alginate were prepared for use as three-dimensional scaffolds for the culture and expansion of cells that are effective for bone tissue engineering. The calcium phosphate cement-alginate composite microcarriers were produced by an emulsification of the composite aqueous solutions mixed at varying ratios (calcium phosphate cement powder/alginate solution = 0.8-1.2) in an oil bath and the subsequent in situ hardening of the compositions during spherodization. Moreover, a porous structure could be easily created in the solid microcarriers by soaking the produced microcarriers in water and a subsequent freeze-drying process. Bone mineral-like apatite nanocrystallites were shown to rapidly develop on the calcium phosphate cement-alginate microcarriers under moist conditions due to the conversion of the α-tricalcium phosphate phase in the calcium phosphate cement into a carbonate-hydroxyapatite. Osteoblastic cells cultured on the microspherical scaffolds were proven to be viable, with an active proliferative potential during 14 days of culture, and their osteogenic differentiation was confirmed by the determination of alkaline phosphatase activity. The in situ hardening calcium phosphate cement-alginate microcarriers developed herein may be used as potential three-dimensional scaffolds for cell delivery and tissue engineering of bone.

  1. Preparation of in situ hardening composite microcarriers: Calcium phosphate cement combined with alginate for bone regeneration

    PubMed Central

    Park, Jung-Hui; Lee, Eun-Jung; Knowles, Jonathan C

    2014-01-01

    Novel microcarriers consisting of calcium phosphate cement and alginate were prepared for use as three-dimensional scaffolds for the culture and expansion of cells that are effective for bone tissue engineering. The calcium phosphate cement-alginate composite microcarriers were produced by an emulsification of the composite aqueous solutions mixed at varying ratios (calcium phosphate cement powder/alginate solution = 0.8–1.2) in an oil bath and the subsequent in situ hardening of the compositions during spherodization. Moreover, a porous structure could be easily created in the solid microcarriers by soaking the produced microcarriers in water and a subsequent freeze-drying process. Bone mineral-like apatite nanocrystallites were shown to rapidly develop on the calcium phosphate cement–alginate microcarriers under moist conditions due to the conversion of the α-tricalcium phosphate phase in the calcium phosphate cement into a carbonate–hydroxyapatite. Osteoblastic cells cultured on the microspherical scaffolds were proven to be viable, with an active proliferative potential during 14 days of culture, and their osteogenic differentiation was confirmed by the determination of alkaline phosphatase activity. The in situ hardening calcium phosphate cement–alginate microcarriers developed herein may be used as potential three-dimensional scaffolds for cell delivery and tissue engineering of bone. PMID:23836845

  2. Smart designing of new hybrid materials based on brushite-alginate and monetite-alginate microspheres: bio-inspired for sequential nucleation and growth.

    PubMed

    Amer, Walid; Abdelouahdi, Karima; Ramananarivo, Hugo Ronald; Fihri, Aziz; El Achaby, Mounir; Zahouily, Mohamed; Barakat, Abdellatif; Djessas, Kamal; Clark, James; Solhy, Abderrahim

    2014-02-01

    In this report new hybrid materials based on brushite-alginate and monetite-alginate were prepared by self-assembling alginate chains and phosphate source ions via a gelation process with calcium ions. The alginate served as nanoreactor for nucleation and growth of brushite or/and monetite due to its gelling and swelling properties. The alginate gel framework, the crystalline phase and morphology of formed hybrid biomaterials were shown to be strongly dependent upon the concentration of the phosphate precursors. These materials were characterized by thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive x-ray analysis (EDX).

  3. Electrophoretic deposition of antibiotic loaded PHBV microsphere-alginate composite coating with controlled delivery potential.

    PubMed

    Chen, Qiang; Li, Wei; Goudouri, Ourania-Menti; Ding, Yaping; Cabanas-Polo, Sandra; Boccaccini, Aldo R

    2015-06-01

    Electrophoretic deposition (EPD) technique has been developed for the fabrication of antibiotic-loaded PHBV microsphere (MS)-alginate antibacterial coatings. The composite coatings deposited from suspensions with different MS concentrations were produced in order to demonstrate the versatility of the proposed method for achieving functional coatings with tailored drug loading and release profiles. Linearly increased deposit mass with increasing MS concentrations was obtained, and MS were found to be homogeneously stabilized in the alginate matrix. Chemical composition, surface roughness and wettability of the deposited coatings were measured by Fourier transform infrared (FTIR) spectroscopy, laser profilometer and water contact angle instruments, respectively. The co-deposition mechanism was described by two separate processes according to the results of relevant measurements: (i) the deposition of alginate-adsorbed MS and (ii) the non-adsorbed alginate. Qualitative antibacterial tests indicated that MS containing coatings exhibit excellent inhibition effects against E. coli (gram-negative bacteria) after 1h of incubation. The proposed coating system combined with the simplicity of the EPD technique can be considered a promising surface modification approach for the controlled in situ delivery of drug or other biomolecules.

  4. Injectable hydrogels embedded with alginate microspheres for controlled delivery of bone morphogenetic protein-2.

    PubMed

    Zhu, Youjia; Wang, Jiulong; Wu, Jingjing; Zhang, Jun; Wan, Ying; Wu, Hua

    2016-03-23

    Some delivery carriers with injectable characteristics were built using the thermosensitive chitosan/dextran-polylactide/glycerophosphate hydrogel and selected alginate microspheres for the controllable release of bone morphogenetic protein-2 (BMP-2). BMP-2 was first loaded into the microspheres with an average size of around 20 μm and the resulting microspheres were then embedded into the gel in order to achieve well-controlled BMP-2 release. The microsphere-embedded gels show their incipient gelation temperature at around 32 °C and pH at about 7.1. Some gels had their elastic modulus close to 1400 Pa and the ratio of elastic modulus to viscous modulus at around 34, revealing that they behaved like mechanically strong gels. Optimized microsphere-embedded gels were found to be able to administer the BMP-2 release without significant initial burst release in an approximately linear manner over a period of time longer than four weeks. The release rate and the released amount of BMP-2 from these gels could be regulated individually or cooperatively by the initial BMP-2 load and the dextran-polylactide content in the gels. Measurements of the BMP-2 induced alkaline phosphatase activity in C2C12 cells confirmed that C2C12 cells responded to BMP-2 in a dose-dependent way and the released BMP-2 from the microsphere-embedded gels well retained their bioactivity. In vivo assessment of some gels revealed that the released BMP-2 maintained its osteogenesis functions.

  5. Biocompatibility and Effectiveness Evaluation of a New Hemostatic Embolization Agent: Thrombin Loaded Alginate Calcium Microsphere

    PubMed Central

    Xuan, Fengqi; Rong, Jingjing; Liang, Ming; Zhang, Xuwen; Sun, Jingyang; Zhao, Lijun; Li, Yang; Liu, Dan; Li, Fei; Wang, Xiaozeng

    2017-01-01

    Background. Until now, there has been no ideal embolization agent for hemorrhage in interventional treatment. In this study, the thrombin was encapsulated in alginate calcium microsphere using electrostatic droplet technique to produce new embolization agent: thrombin loaded alginate calcium microspheres (TACMs). Objectives. The present work was to evaluate the biocompatibility and hemostatic efficiency of TACMs. Methods. Cell cytotoxicity, hemolysis, and superselective embolization of dog liver arteries were performed to investigate the biocompatibility of TACMs. To clarify the embolic effect of TACMs mixed thrombus in vivo, hepatic artery injury animal model of 6 beagles was established and transcatheter artery embolization for bleeding was performed. Results. Coculture with VECs revealed the noncytotoxicity of TACMs, and the hemolysis experiment was negligible. Moreover, the histological study of TACMs in liver blood vessel showed signs of a slight inflammatory reaction. The results of transcatheter application of TACMs mixed thrombus for bleeding showed that the blood flow was shut down completely after the TACMs mixed thrombus was delivered and the postprocedural survival rate of animal models at 12 weeks was 100%. Conclusions. With their good biocompatibility and superior hemostatic efficiency, TACMs might be a promising new hemostatic agent with a wide range of potential applications. PMID:28303245

  6. Preparation, Drug Releasing Property and Pharmacodynamics of Soy Isoflavone-Loaded Chitosan Microspheres

    PubMed Central

    Du, Zhongyan; Dou, Xiaobing; Huang, Chenyun; Gao, Jia; Hu, Linfeng; Zhu, Jiazhen; Qian, Ying; Dou, Minhua; Fan, Chunlei

    2013-01-01

    Soybean isoflavone (SIF) has anti-aging properties and many other biological functions; however, SIF is difficult to reach higher blood concentration due to its rapid metabolism. Therefore, it is of great value to design and produce a sustained-release formulation that is able to maintain a stable level of plasma concentrations. In this paper, soybean isoflavone sustained-release microsphere from chitosan and sodium alginate was prepared successfully. The important factors that determined the quality of the microspheres were the sodium alginate concentration in solution B, the ratio of soybean isoflavone to chitosan and the mixing speed. The relative yield, encapsulation efficiency and drug loading capability of SIF were much higher than the existing commercial formulations. In real gastrointestinal conditions, compared with the non-sustained release group, the release rate of SIF slowed down and the reaction time was prolonged. Animal experiments showed that sustained-release microspheres intensified the anti-aging potentials of SIF. Compared with the Non-sustained release (NSR) group mice, oral SIF/CHI microsphere treated mice were better in the Morris Water Maze Test (MWMT), the MDA level in the both plasma and brain of the sustained release(SR) group mice decreased, and SOD content was remarkably improved. PMID:24244544

  7. A Simple Method for Encapsulating Single Cells in Alginate Microspheres Allows for Direct PCR and Whole Genome Amplification

    PubMed Central

    Bigdeli, Saharnaz; Dettloff, Roger O.; Frank, Curtis W.; Davis, Ronald W.; Crosby, Laurel D.

    2015-01-01

    Microdroplets are an effective platform for segregating individual cells and amplifying DNA. However, a key challenge is to recover the contents of individual droplets for downstream analysis. This paper offers a method for embedding cells in alginate microspheres and performing multiple serial operations on the isolated cells. Rhodobacter sphaeroides cells were diluted in alginate polymer and sprayed into microdroplets using a fingertip aerosol sprayer. The encapsulated cells were lysed and subjected either to conventional PCR, or whole genome amplification using either multiple displacement amplification (MDA) or a two-step PCR protocol. Microscopic examination after PCR showed that the lumen of the occupied microspheres contained fluorescently stained DNA product, but multiple displacement amplification with phi29 produced only a small number of polymerase colonies. The 2-step WGA protocol was successful in generating fluorescent material, and quantitative PCR from DNA extracted from aliquots of microspheres suggested that the copy number inside the microspheres was amplified up to 3 orders of magnitude. Microspheres containing fluorescent material were sorted by a dilution series and screened with a fluorescent plate reader to identify single microspheres. The DNA was extracted from individual isolates, re-amplified with full-length sequencing adapters, and then a single isolate was sequenced using the Illumina MiSeq platform. After filtering the reads, the only sequences that collectively matched a genome in the NCBI nucleotide database belonged to R. sphaeroides. This demonstrated that sequencing-ready DNA could be generated from the contents of a single microsphere without culturing. However, the 2-step WGA strategy showed limitations in terms of low genome coverage and an uneven frequency distribution of reads across the genome. This paper offers a simple method for embedding cells in alginate microspheres and performing PCR on isolated cells in common bulk

  8. A simple method for encapsulating single cells in alginate microspheres allows for direct PCR and whole genome amplification.

    PubMed

    Bigdeli, Saharnaz; Dettloff, Roger O; Frank, Curtis W; Davis, Ronald W; Crosby, Laurel D

    2015-01-01

    Microdroplets are an effective platform for segregating individual cells and amplifying DNA. However, a key challenge is to recover the contents of individual droplets for downstream analysis. This paper offers a method for embedding cells in alginate microspheres and performing multiple serial operations on the isolated cells. Rhodobacter sphaeroides cells were diluted in alginate polymer and sprayed into microdroplets using a fingertip aerosol sprayer. The encapsulated cells were lysed and subjected either to conventional PCR, or whole genome amplification using either multiple displacement amplification (MDA) or a two-step PCR protocol. Microscopic examination after PCR showed that the lumen of the occupied microspheres contained fluorescently stained DNA product, but multiple displacement amplification with phi29 produced only a small number of polymerase colonies. The 2-step WGA protocol was successful in generating fluorescent material, and quantitative PCR from DNA extracted from aliquots of microspheres suggested that the copy number inside the microspheres was amplified up to 3 orders of magnitude. Microspheres containing fluorescent material were sorted by a dilution series and screened with a fluorescent plate reader to identify single microspheres. The DNA was extracted from individual isolates, re-amplified with full-length sequencing adapters, and then a single isolate was sequenced using the Illumina MiSeq platform. After filtering the reads, the only sequences that collectively matched a genome in the NCBI nucleotide database belonged to R. sphaeroides. This demonstrated that sequencing-ready DNA could be generated from the contents of a single microsphere without culturing. However, the 2-step WGA strategy showed limitations in terms of low genome coverage and an uneven frequency distribution of reads across the genome. This paper offers a simple method for embedding cells in alginate microspheres and performing PCR on isolated cells in common bulk

  9. Removal of phosphate from aqueous solution using magnesium-alginate/chitosan modified biochar microspheres derived from Thalia dealbata.

    PubMed

    Cui, Xiaoqiang; Dai, Xi; Khan, Kiran Yasmin; Li, Tingqiang; Yang, Xiaoe; He, Zhenli

    2016-10-01

    The objective of this study was to determine the feasibility of using magnesium-alginate/chitosan modified biochar microspheres to enhance removal of phosphate from aqueous solution. The introduction of MgCl2 substantially increased surface area of biochar (116.2m(2)g(-1)), and both granulation with alginate/chitosan and modification with magnesium improved phosphate sorption on the biochars. Phosphate sorption on the biochars could be well described by a simple Langmuir model, and the MgCl2-alginate modified biochar microspheres exhibited the highest phosphate sorption capacity (up to 46.56mgg(-1)). The pseudo second order kinetic model better fitted the kinetic data, and both the Yoon-Nelson and Thomas models were superior to other models in describing phosphate dynamic sorption. Precipitation with minerals and ligand exchange were the possible mechanisms of phosphate sorption on the modified biochars. These results imply that MgCl2-alginate modified biochar microspheres have potential as a green cost-effective sorbent for remediating P contaminated water environment.

  10. PREPARATION OF REFRACTORY OXIDE MICROSPHERE

    DOEpatents

    Haws, C.C. Jr.

    1963-09-24

    A method is described of preparing thorium oxide in the form of fused spherical particles about 1 to 2 microns in diameter. A combustible organic solution of thorium nitrate containing additive metal values is dispersed into a reflected, oxygen-fed flame at a temperature above the melting point of the resulting oxide. The metal additive is aluminum at a proportion such as to provide 1 to 10 weight per cent aluminum oxide in the product, silicon at the same proportion, or beryllium at a proportion of 12 to 25 weight per cent beryllium oxide in the product. A minor proportion of uranium values may also be provided in the solution. The metal additive lowers the oxide melting point and allows fusion and sphere formation in conventional equipment. The product particles are suitable for use in thorium oxide slurries for nuclear reactors. (AEC)

  11. Preparation of monodisperse aqueous microspheres containing high concentration of l-ascorbic acid by microchannel emulsification.

    PubMed

    Khalid, Nauman; Kobayashi, Isao; Neves, Marcos A; Uemura, Kunihiko; Nakajima, Mitsutoshi; Nabetani, Hiroshi

    2015-01-01

    Monodisperse aqueous microspheres containing high concentrations of l-ascorbic acid with different concentrations of sodium alginate (Na-ALG) and magnesium sulfate (MgSO4) were prepared by using microchannel emulsification (MCE). The continuous phase was water-saturated decane containing a 5% (w/w) hydrophobic emulsifier. The flow rate of the continuous phase was maintained at 10 mL h(-1), whereas the pressure applied to the disperse phase was varied between 3 and 25 kPa. The disperse phase optimized for successfully generating aqueous microspheres included 2% (w/w) Na-ALG and 1% (w/w) MgSO4. At a higher MgSO4 concentration, the generated microspheres resulted in coalescence and subsequent bursting. At a lower MgSO4 concentration, unstable and polydisperse microspheres were obtained. The aqueous microspheres generated from the MCs under optimized conditions had a mean particle diameter (dav) of 14-16 µm and a coefficient of variation (CV) of less than 8% at the disperse phase pressures of 5-15 kPa.

  12. Preparation and properties of polyvinyl alcohol microspheres

    SciTech Connect

    Campbell, J.H.; Grens, J.Z.; Poco, J.F.; Ives, B.H.

    1986-06-01

    Polyvinyl alcohol (PVA) microspheres, having a size range of approx.150- to 250-..mu..m diameter with 1- to 5-..mu..m wall thickness, have been fabricated using a solution droplet technique. The spheres were developed for possible use on the Lawrence Livermore National Laboratory (LLNL) Inertial Confinement Fusion (ICF) Program. PVA, a polymer chosen based on earlier survey work carried out at KMS Fusion, Inc., has good strength, low hydrogen permeability, is optically transparent, and water soluble. The latter property makes it safe and easy to use in our droplet generator system. A unique dual-orifice droplet generator was used to prepare the spheres. The droplet generator operating conditions and the column processing parameters were chosen using results from our 1-D model calculations as a guide. The polymer microsphere model is an extension of the model we developed to support the glass sphere production. After preparation, the spheres were physically characterized for surface quality, sphericity, wall thickness (and uniformity), and size. We also determined the buckling pressure for both uncoated and CH-coated spheres. Radiation stability to beta decay (from tritium) was evaluated by exposing the spheres to a 7-keV electron beam. The results from these and other physical property measurements are presented in this report.

  13. Preparation and evaluation of sustained release loxoprofen loaded microspheres

    PubMed Central

    Venkatesan, P.; Manavalan, R.; Valliappan, K.

    2011-01-01

    The aim of present study was to formulate and evaluate the loxoprofen loaded Sustained release microspheres by emulsion solvent evaporation technique. Ethylcellulose, a biocompatible polymer is used as the retardant material. The effects of process conditions such as drug loading, polymer type and solvent type on the characteristics of microspheres were investigated. The prepared microspheres were characterized for their particle size and drug loading and drug release. The in-vitro release studies were carried out in phosphate buffer at pH 7.4. The prepared microspheres were white, free flowing and spherical in shape. The drug-loaded microspheres showed 71.2% of entrapment and the in-vitro release studies showed that Loxoprofen microspheres of 1:3 ratios showed better sustained effect over a period of 8 hours PMID:24826017

  14. Encapsulation in alginate-skim milk microspheres improves viability of Lactobacillus bulgaricus in stimulated gastrointestinal conditions.

    PubMed

    Pan, Ling-Xia; Fang, Xiu-Juan; Yu, Zhen; Xin, Yang; Liu, Xiao-Ying; Shi, Lu-E; Tang, Zhen-Xing

    2013-05-01

    Lactobacillus delbrueckii subsp. bulgaricus (L. bulgaricus) was encapsulated in alginate-skim milk microspheres. Characteristics of encapsulated L. bulgaricus, such as pH stability, bile stability, storage stability and release property, were studied in this paper. The viability of free L. bulgaricus was not observed after 1 min in simulated gastric fluids (SGF) at pH 2.5 or 2.0. Compared with that of free L. bulgaricus, the viability of encapsulated L. bulgaricus only decreased 0.7 log CFU/g and 2 log CFU/g after 2.0 h incubation in SGF at pH 2.5 and pH 2.0, respectively. L. bulgaricus was also sensitive to bile solution. The viability of free L. bulgaricus was fully lost after 1 h incubation in 1 and 2% bile solution, while the viability of encapsulated L. bulgaricus was only lost 2 log CFU/g and 2.6 log CFU/g in 1 and 2% bile solution at the same time, respectively. Encapsulated L. bulgaricus could be completely released from microspheres in simulated intestinal fluid (pH 6.8) within 2 h. The viability of encapsulated L. bulgaricus retained around 8 log CFU/g when stored at 4°C for 30 days. The current encapsulation technique enables a large proportion of L. bulgaricus to remain good bioactive in a simulated gastrointestinal tract environment.

  15. Microspheres and their methods of preparation

    DOEpatents

    Bose, Anima B; Yang, Junbing

    2015-03-24

    Carbon microspheres are doped with boron to enhance the electrical and physical properties of the microspheres. The boron-doped carbon microspheres are formed by a CVD process in which a catalyst, carbon source and boron source are evaporated, heated and deposited onto an inert substrate.

  16. Preparation of alginate beads containing a prodrug of diethylenetriaminepentaacetic acid

    PubMed Central

    Yang, Yu-Tsai; Di Pasqua, Anthony J.; He, Weiling; Tsai, Tsuimin; Sueda, Katsuhiko; Zhang, Yong; Jay, Michael

    2012-01-01

    A penta-ethyl ester prodrug of the radionuclide decorporation agent diethylenetriaminepentaacetic acid (DTPA), which exists as an oily liquid, was encapsulated in alginate beads by the ionotropic gelation method. An optimal formulation was found by varying initial concentrations of DTPA pentaethyl ester, alginate polymer, Tween 80 surfactant and calcium chloride. All prepared alginate beads were ~1.6 mm in diameter, and the optimal formulation had loading and encapsulation efficiencies of 91.0 ± 1.1 and 72.6 ± 2.2%, respectively, and only 3.2 ± 0.8% water absorption after storage at room temperature in ~80% relative humidity. Moreover, Fourier transform infrared spectroscopy showed that DTPA penta-ethyl ester did not react with excipients during formation of the DTPA penta-ethyl ester-containing alginate beads. Release of prodrug from alginate beads was via anomalous transport, and its stability enhanced by encapsulation. Collectively, these data suggest that this solid dosage form may be suitable for oral administration after radionuclide contamination. PMID:23399237

  17. Microencapsulated Aliivibrio fischeri in alginate microspheres for monitoring heavy metal toxicity in environmental waters.

    PubMed

    Futra, Dedi; Heng, Lee Yook; Surif, Salmijah; Ahmad, Asmat; Ling, Tan Ling

    2014-12-05

    In this article a luminescence fiber optic biosensor for the microdetection of heavy metal toxicity in waters based on the marine bacterium Aliivibrio fischeri (A. fischeri) encapsulated in alginate microspheres is described. Cu(II), Cd(II), Pb(II), Zn(II), Cr(VI), Co(II), Ni(II), Ag(I) and Fe(II) were selected as sample toxic heavy metal ions for evaluation of the performance of this toxicity microbiosensor. The loss of bioluminescence response from immobilized A. fischeri bacterial cells corresponds to changes in the toxicity levels. The inhibition of the luminescent biosensor response collected at excitation and emission wavelengths of 287 ± 2 nm and 487 ± 2 nm, respectively, was found to be reproducible and repeatable within the relative standard deviation (RSD) range of 2.4-5.7% (n = 8). The toxicity biosensor based on alginate micropsheres exhibited a lower limit of detection (LOD) for Cu(II) (6.40 μg/L), Cd(II) (1.56 μg/L), Pb(II) (47 μg/L), Ag(I) (18 μg/L) than Zn(II) (320 μg/L), Cr(VI) (1,000 μg/L), Co(II) (1700 μg/L), Ni(II) (2800 μg/L), and Fe(III) (3100 μg/L). Such LOD values are lower when compared with other previous reported whole cell toxicity biosensors using agar gel, agarose gel and cellulose membrane biomatrices used for the immobilization of bacterial cells. The A. fischeri bacteria microencapsulated in alginate biopolymer could maintain their metabolic activity for a prolonged period of up to six weeks without any noticeable changes in the bioluminescence response. The bioluminescent biosensor could also be used for the determination of antagonistic toxicity levels for toxicant mixtures. A comparison of the results obtained by atomic absorption spectroscopy (AAS) and using the proposed luminescent A. fischeri-based biosensor suggests that the optical toxicity biosensor can be used for quantitative microdetermination of heavy metal toxicity in environmental water samples.

  18. Microencapsulated Aliivibrio fischeri in Alginate Microspheres for Monitoring Heavy Metal Toxicity in Environmental Waters

    PubMed Central

    Futra, Dedi; Heng, Lee Yook; Surif, Salmijah; Ahmad, Asmat; Ling, Tan Ling

    2014-01-01

    In this article a luminescence fiber optic biosensor for the microdetection of heavy metal toxicity in waters based on the marine bacterium Aliivibrio fischeri (A. fischeri) encapsulated in alginate microspheres is described. Cu(II), Cd(II), Pb(II), Zn(II), Cr(VI), Co(II), Ni(II), Ag(I) and Fe(II) were selected as sample toxic heavy metal ions for evaluation of the performance of this toxicity microbiosensor. The loss of bioluminescence response from immobilized A. fischeri bacterial cells corresponds to changes in the toxicity levels. The inhibition of the luminescent biosensor response collected at excitation and emission wavelengths of 287 ± 2 nm and 487 ± 2 nm, respectively, was found to be reproducible and repeatable within the relative standard deviation (RSD) range of 2.4–5.7% (n = 8). The toxicity biosensor based on alginate micropsheres exhibited a lower limit of detection (LOD) for Cu(II) (6.40 μg/L), Cd(II) (1.56 μg/L), Pb(II) (47 μg/L), Ag(I) (18 μg/L) than Zn(II) (320 μg/L), Cr(VI) (1,000 μg/L), Co(II) (1700 μg/L), Ni(II) (2800 μg/L), and Fe(III) (3100 μg/L). Such LOD values are lower when compared with other previous reported whole cell toxicity biosensors using agar gel, agarose gel and cellulose membrane biomatrices used for the immobilization of bacterial cells. The A. fischeri bacteria microencapsulated in alginate biopolymer could maintain their metabolic activity for a prolonged period of up to six weeks without any noticeable changes in the bioluminescence response. The bioluminescent biosensor could also be used for the determination of antagonistic toxicity levels for toxicant mixtures. A comparison of the results obtained by atomic absorption spectroscopy (AAS) and using the proposed luminescent A. fischeri-based biosensor suggests that the optical toxicity biosensor can be used for quantitative microdetermination of heavy metal toxicity in environmental water samples. PMID:25490588

  19. Investigation of the strontium (Sr(II)) adsorption of an alginate microsphere as a low-cost adsorbent for removal and recovery from seawater.

    PubMed

    Hong, Hye-Jin; Ryu, Jungho; Park, In-Su; Ryu, Taegong; Chung, Kang-Sup; Kim, Byuong-Gyu

    2016-01-01

    In this paper, we investigated alginate microspheres as a low-cost adsorbent for strontium (Sr(II)) removal and recovery from seawater. Alginate microspheres have demonstrated a superior adsorption capacity for Sr(II) ions (≈110 mg/g). A Freundlich isotherm model fits well with the Sr(II) adsorption of an alginate microsphere. The mechanism of Sr(II) adsorption is inferred as an ion exchange reaction with Ca(II) ions. The effects of the solution pH and co-existing ions in seawater are also investigated. Except for a pH of 1-2, Sr(II) adsorption capacity is not affected by pH. However, increasing the seawater concentration of metal cations seriously decreases Sr(II) uptake. In particular, highly concentrated (15,000 mg/L) Na(I) ions significantly interfere with Sr(II) adsorption. Sr(II) desorption was performed using 0.1 M HCl and CaCl2. Both regenerants show an excellent desorption efficiency, but the FTIR spectrum reveals that the chemical structure of the microsphere is destroyed after repeated use of HCl. Conversely, CaCl2 successfully desorbed Sr(II) without damage, and the Sr(II) adsorption capacity does not decrease after three repeated uses. The alginate microsphere was also applied to the adsorption of Sr(II) in a real seawater medium. Because of inhibition by co-existing ions, the Sr(II) adsorption capacity was decreased and the adsorption rate was retarded compared with D.I. water. Although the Sr(II) adsorption capacity was decreased, the alginate microsphere still exhibited 17.8 mg/g of Sr(II) uptake in the seawater medium. Considering its excellent Sr(II) uptake in seawater and its reusability, an alginate microsphere is an appropriate cost-effective adsorbent for the removal and recovery of Sr(II) from seawater.

  20. Bioinspired preparation of alginate nanoparticles using microbubble bursting.

    PubMed

    Elsayed, Mohamed; Huang, Jie; Edirisinghe, Mohan

    2015-01-01

    Nanoparticles are considered to be one of the most advanced tools for drug delivery applications. In this research, alginate (a model hydrophilic polymer) nanoparticles 80 to 200 nm in diameter were obtained using microbubble bursting. The natural process of bubble bursting occurs through a number of stages, which consequently produce nano- and microsized droplets via two main production mechanisms, bubble shell disintegration and a jetting process. In this study, nano-sized droplets/particles were obtained by promoting the disintegrating mechanism and suppressing (limiting) the formation of larger microparticles resulting from the jetting mechanism. A T-junction microfluidic device was used to prepare alginate microbubbles with different sizes in a well-controlled manner. The size of the bubbles was varied by controlling two processing parameters, the solution flow rate and the bubbling pressure. Crucially, the bubble size was found to be the determining factor for inducing (or limiting) the bubble shell disintegration mechanism and the size needed to promote this process was influenced by the properties of the solution used for preparing the bubbles, particularly the viscosity. The size of alginate nanoparticles produced via the disintegration mechanism was found to be directly proportional to the viscosity of the alginate solution.

  1. X-ray visible and uniform alginate microspheres loaded with in situ synthesized BaSO4 nanoparticles for in vivo transcatheter arterial embolization.

    PubMed

    Wang, Qin; Qian, Kun; Liu, Shanshan; Yang, Yajiang; Liang, Bin; Zheng, Chuansheng; Yang, Xiangliang; Xu, Huibi; Shen, Amy Q

    2015-04-13

    The lack of noninvasive tracking and mapping the fate of embolic agents has restricted the development and further applications of the transcatheter arterial embolization (TAE) therapy. In this work, inherent radiopaque embolic material, barium alginate (ALG) microspheres loaded with in situ synthesized BaSO4 (denoted as BaSO4/ALG microspheres), have been synthesized by a one-step droplet microfluidic technique. One of the advantages of our microfluidic approach is that radiopaque BaSO4 is in the form of nanoparticles and well dispersed inside ALG microspheres, thereby greatly enhancing the imaging quality. The crystal structure of in situ synthesized BaSO4 nanoparticles in ALG microspheres is confirmed by X-ray diffraction analysis. Results of in vitro and in vivo assays from digital subtraction angiography and computed tomography scans demonstrate that BaSO4/ALG microspheres possess excellent visibility under X-ray. Histopathological analysis verifies that the embolic efficacy of BaSO4/ALG microspheres is similar to that of commercially available alginate microsphere embolic agents. Furthermore, the visibility of radiopaque BaSO4/ALG microspheres under X-ray promises the direct detection of the embolic efficiency and position of embolic microspheres after embolism, which offers great promises in direct real-time in vivo investigations for TAE.

  2. Preparation of mesoporous zirconia microspheres as inert matrix

    NASA Astrophysics Data System (ADS)

    Guo, Ting; Wang, Chen; Lv, Jinlong; Liang, Tongxiang

    2016-12-01

    Mesoporous zirconia microspheres, with a diameter of 900 μm, were prepared as an inert accelerator driven system (ADS) transmutation element matrix by the sol-gel method. The purpose of mesopores is to improve the adsorption capacity of inert matrix fuel (IMF) for minor actinides. The study indicated that the mesoporous zirconia performance was improved after the microspheres were hydrothermally treated at 150 °C, the specific surface area increased from 28.29 m2/g to 61.28 m2/g, and hydrothermal treatment avoided the cracking of the microspheres. Pre-decomposition of the organics during the hydrothermal process stabilized the mesoporous structure. The average pore diameter of mesoporous microsphere was 14.3 nm.

  3. Mucoadhesive microspheres prepared by interpolymer complexation and solvent diffusion method.

    PubMed

    Chun, Myung-Kwan; Cho, Chong-Su; Choi, Hoo-Kyun

    2005-01-20

    Mucoadhesive microspheres were prepared to increase gastric residence time using an interpolymer complexation of poly(acrylic acid) (PAA) with poly(vinyl pyrrolidone) (PVP) and a solvent diffusion method. The complexation between poly(acrylic acid) and poly(vinyl pyrrolidone) as a result of hydrogen bonding was confirmed by the shift in the carbonyl absorption bands of poly(acrylic acid) using FT-IR. A mixture of ethanol/water was used as the internal phase, corn oil was used as the external phase of emulsion, and span 80 was used as the surfactant. Spherical microspheres were prepared and the inside of the microspheres was completely filled. The optimum solvent ratio of the internal phase (ethanol/water) was 8/2 and 7/3, and the particle size increased as the content of water was increased. The mean particle size increased with the increase in polymer concentration. The adhesive force of microspheres was equivalent to that of Carbopol. The release rate of acetaminophen from the complex microspheres was slower than the PVP microspheres at pH 2.0 and 6.8.

  4. Co-encapsulation of anti-BMP2 monoclonal antibody and mesenchymal stem cells in alginate microspheres for bone tissue engineering

    PubMed Central

    Moshaverinia, Alireza; Ansari, Sahar; Chen, Chider; Xu, Xingtian; Akiyama, Kentaro; Snead, Malcolm L.; Zadeh, Homayoun H.; Shi, Songtao

    2013-01-01

    Recently, it has been shown that tethered anti-BMP2 monoclonal antibodies (mAbs) can trap BMP ligands and thus provide BMP inductive signals for osteo-differentiation of progenitor cells. The objectives of this study were to: (1) develop a co-delivery system based on murine anti-BMP2 mAb-loaded alginate microspheres encapsulating human bone marrow mesenchymal stem cells (hBMMSCs); and (2) investigate osteogenic differentiation of encapsulated stem cells in alginate microspheres in vitro and in vivo. Alginate microspheres of 1 ± 0.1 mm diameter were fabricated with 2 × 106 hBMMSCs per mL of alginate. Critical-size calvarial defects (5 mm diameter) were created in immune-compromised mice and alginate microspheres preloaded with anti-BMP mAb encapsulating hBMMSCs were transplanted into defect sites. Alginate microspheres pre-loaded with isotype-matched non-specific antibody was used as the negative control. After 8 weeks, micro CT and histologic analysis were used to analyze bone formation. In vitro analysis demonstrated that anti-BMP2 mAbs tethered BMP2 ligands that can activate the BMP receptors on hBMMSCs. The co-delivery system described herein, significantly enhanced hBMMSC-mediated osteogenesis, as confirmed by the presence of BMP signal pathway-activated osteoblast determinants Runx2 and ALP. Our results highlight the importance of engineering the microenvironment for stem cells, and particularly the value of presenting inductive signals for osteo-differentiation of hBMMSCs by tethering BMP ligands using mAbs. This strategy of engineering the microenvironment with captured BMP signals is a promising modality for repair and regeneration of craniofacial, axial and appendicular bone defects. PMID:23773817

  5. Preparation of antibacterial silver-doped silica glass microspheres.

    PubMed

    Kawashita, Masakazu; Toda, Shogo; Kim, Hyun-Min; Kokubo, Tadashi; Masuda, Noriaki

    2003-08-01

    Various types of inorganic substances doped with silver ions have been developed as antibacterial materials, and some have already been commercialized. Colorless and chemically durable materials that slowly release silver ions are, however, still need to be developed. The present authors have previously shown that when a silica glass doped with silver and aluminium ions is prepared using the sol-gel method, the resultant product is colorless, chemically durable, and slowly releases silver ions into water over a long period. The doped silica glass takes a form of microspheres <1 microm in diameter, it is easily mixed with organic polymers, and the mixture can be formed into a thin film or fine fibers, etc. We report on the preparation of silver doped silica glass microspheres having a diameter =1 microm, using the sol-gel method. Initially, tetraethoxysilane was partially prehydrolyzed by water in ethanol, and then aluminium triisopropoxide was added to the solution to form Si-O-Al bonds. Finally, an ammonia solution containing silver nitrate was added to form silica microspheres doped with silver ion together with aluminium ions. The results show monodispersed microspheres 0.4-0.6 microm in diameter were obtained with nominal compositions of Si/Al/Ag = 1/0.01-0.03/0.003-0.03, with a molar ratio of Al/Ag = 1-3.3. The microspheres were colorless, showed a high chemical durability, and slowly released silver ions into water at 37 degrees C. Microspheres with the composition Si/Al/Ag = 1/0.01/0.01 showed excellent antibacterial activity against Escherichia coli. The minimum inhibitory concentration (MIC) of the microspheres was 400, which is less than the MIC value (800) of commercial antibacterial materials.

  6. Bio-based barium alginate film: Preparation, flame retardancy and thermal degradation behavior.

    PubMed

    Liu, Yun; Zhang, Chuan-Jie; Zhao, Jin-Chao; Guo, Yi; Zhu, Ping; Wang, De-Yi

    2016-03-30

    A bio-based barium alginate film was prepared via a facile ionic exchange and casting approach. Its flammability, thermal degradation and pyrolysis behaviors, thermal degradation mechanism were studied systemically by limiting oxygen index (LOI), vertical burning (UL-94), microscale combustion calorimetry (MCC), thermogravimetric analysis (TGA) coupled with Fourier transform infrared analysis (FTIR) and pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS). It showed that barium alginate film had much higher LOI value (52.0%) than that of sodium alginate film (24.5%). Moreover, barium alginate film passed the UL-94 V-0 rating, while the sodium alginate film showed no classification. Importantly, peak of heat release rate (PHRR) of barium alginate film in MCC test was much lower than that of sodium alginate film, suggested that introduction of barium ion into alginate film significantly decreased release of combustible gases. TG-FTIR and Py-GC-MS results indicated that barium alginate produced much less flammable products than that of sodium alginate in whole thermal degradation procedure. Finally, a possible degradation mechanism of barium alginate had been proposed.

  7. [Study on preparation process of artesunate polylactic acid microspheres].

    PubMed

    Pan, Xu-Wang; Wang, Wei; Fang, Hong-Ying; Wang, Fu-Gen; Cai, Zhao-Bin

    2013-12-01

    This study aims to investigate the preparation process and in vitro release behavior of artesunate polylactic acid microspheres, in order to prepare an artesunate polylactic acid (PLA) administration method suitable for hepatic arterial embolization. With PLA as the material and polyvinyl alcohol (PVA) as the emulsifier, O/W emulsion/solvent evaporation method was adopted to prepare artesunate polylactic acid microspheres, and optimize the preparation process. With drug loading capacity, encapsulation efficiency and particle size as indexes, a single factor analysis was made on PLA concentration, PVA concentration, drug loading ratio and stirring velocity. Through an orthogonal experiment, the optimal processing conditions were determined as follows: PLA concentration was 9. 0% , PVA concentration was 0. 9% , drug loading ratio was 1:2 and stirring velocity was 1 000 r x min(-1). According to the verification of the optimal process, microsphere size, drug loading and entrapment rate of artesunate polylactic acid microspheres were (101.7 +/- 0.37) microm, (30.8 +/- 0.84)%, (53.6 +/- 0.62)%, respectively. The results showed that the optimal process was so reasonable and stable that it could lay foundation for further studies.

  8. Preparation of petaloid microspheres of basic magnesium carbonate.

    PubMed

    Ohkubo, Takahiro; Suzuki, Sei; Mitsuhashi, Kohei; Ogura, Taku; Iwanaga, Shinichi; Sakai, Hideki; Koishi, Masumi; Abe, Masahiko

    2007-05-22

    The synthesis of basic magnesium carbonate was examined under ultrasonic irradiation and was performed by the soda ash method using magnesium sulfate and sodium carbonate as starting materials. The particulate product was evaluated using SEM observations. Ultrasonic irradiation in the preparation of basic magnesium carbonate was found to give fine petaloid microspheres of about 3 mum in primary particle size.

  9. Novel calcium-alginate capsules with aqueous core and thermo-responsive membrane.

    PubMed

    Wang, Ji-Yun; Jin, Yao; Xie, Rui; Liu, Jie-Yi; Ju, Xiao-Jie; Meng, Tao; Chu, Liang-Yin

    2011-01-01

    Novel calcium-alginate (Ca-alginate) capsules with aqueous core and thermo-responsive membrane are successfully prepared by introducing a co-extrusion minifluidic approach, and the thermo-responsive gating characteristics of Ca-alginate capsule membranes embedded with poly(N-isopropylacrylamide) (PNIPAM) microspheres are investigated systematically. The experimental results show that the prepared Ca-alginate capsules are highly monodisperse, and the average diameter and membrane thickness of Ca-alginate capsules are about 2.96 mm and 0.11 mm respectively. The Ca-alginate capsule membranes exhibit desired thermo-responsive gating property. With increasing the content of PNIPAM microspheres embedded in the Ca-alginate capsule membranes, the thermo-responsive gating coefficient of the capsule membranes increases simply. When solute molecules diffuse through the capsule membrane, the thermo-responsive gating coefficient is significantly affected by the molecular weight of solute molecules.

  10. Preparation of uniform magnetic recoverable catalyst microspheres with hierarchically mesoporous structure by using porous polymer microsphere template

    PubMed Central

    2014-01-01

    Merging nanoparticles with different functions into a single microsphere can exhibit profound impact on various applications. However, retaining the unique properties of each component after integration has proven to be a significant challenge. Our previous research demonstrated a facile method to incorporate magnetic nanoparticles into porous silica microspheres. Here, we report the fabrication of porous silica microspheres embedded with magnetic and gold nanoparticles as magnetic recoverable catalysts. The as-prepared multifunctional composite microspheres exhibit excellent magnetic and catalytic properties and a well-defined structure such as uniform size, high surface area, and large pore volume. As a result, the very little composite microspheres show high performance in catalytic reduction of 4-nitrophenol, special convenient magnetic separability, long life, and good reusability. The unique nanostructure makes the microspheres a novel stable and highly efficient catalyst system for various catalytic industry processes. PMID:24708885

  11. Alginate/bacterial cellulose nanocomposite beads prepared using Gluconacetobacter xylinus and their application in lipase immobilization.

    PubMed

    Kim, Ji Hyun; Park, Saerom; Kim, Hyungsup; Kim, Hyung Joo; Yang, Yung-Hun; Kim, Yong Hwan; Jung, Sang-Kyu; Kan, Eunsung; Lee, Sang Hyun

    2017-02-10

    Alginate/bacterial cellulose nanocomposite beads, with well-controlled size and regular spherical shapes, were prepared in a simple manner by entrapping Gluconacetobacter xylinus in barium alginate hydrogel beads, followed by cultivation of the entrapped cells in culture media with a low sodium ion concentration. The entire surface of the alginate hydrogel beads containing the cells was covered with cellulose fibers (∼30nm) after 36h of cultivation. The cellulose crystallinity index of the alginate/bacterial cellulose beads was 0.7, which was slightly lower than that of bacterial cellulose prepared by cultivating dispersed cells. The water vapor sorption capacity of the alginate/bacterial cellulose beads increased significantly from 0.07 to 38.00 (g/g dry bead) as cultivation time increased. These results clearly indicate that alginate/bacterial cellulose beads have a much higher surface area, crystallinity, and water-holding capacity than alginate beads. The immobilization of lipase on the surface of the nanocomposite beads was also investigated as a potential application of this system. The activity and specific activity of lipase immobilized on alginate/bacterial cellulose beads were 2.6- and 3.8-fold higher, respectively, than that of lipase immobilized on cellulose beads. The alginate/bacterial cellulose nanocomposite beads prepared in this study have several potential applications in the biocatalytic, biomedical, and pharmaceutical fields because of their biocompatibility, biodegradability, high crystallinity, and large surface area.

  12. [Preparation of scopolamine hydrobromide nanoparticles-in-microsphere system].

    PubMed

    Lü, Wei-ling; Hu, Jin-hong; Zhu, Quan-gang; Li, Feng-qian

    2010-07-01

    This study is to prepare scopolamine hydrobromide nanoparticles-in-microsphere system (SH-NiMS) and evaluate its drug release characteristics in vitro. SH nanoparticles were prepared by ionic crosslinking method with tripolyphosphate (TPP) as crosslinker and chitosan as carrier. Orthogonal design was used to optimize the formulation of SH nanoparticles, which took the property of encapsulation efficiency and drug loading as evaluation parameters. With HPMC as carrier, adjusted the parameters of spray drying technique and sprayed the SH nanoparticles in microspheres encaposulated by HPMC was formed and which is called nanoparticles-in-microsphere system (NiMS). SH-NiMS appearances were observed by SEM, structure was obsearved by FT-IR and the release characteristics in vitro were evaluated. The optimized formulation of SH nanoparticles was TPP/CS 1:3 (w/w), HPMC 0.3%, SH 0.2%. The solution peristaltic speed of the spray drying technique was adjusted to 15%, and the temperature of inlet was 110 degrees C. The encapsulation product yeild, drug loading and particle sizes of SH-NiMS were 94.2%, 20.4%, and 1256.5 nm, respectively. The appearances and the structure of SH-NiMS were good. The preparation method of SH-NiMS is stable and reliable to use, which provide a new way to develop new dosage form.

  13. Gelling process for sodium alginate: New technical approach by using calcium rich micro-spheres.

    PubMed

    Vicini, Silvia; Castellano, Maila; Mauri, Marco; Marsano, Enrico

    2015-12-10

    Alginate based materials have become an important class of products in many fields from the pharmaceutical industry to tissue engineering, because of their ability to create stimuli responsive hydrogels. We present a new technical approach for obtaining a controlled gelling process, based on the quantities of Ca(2+) rich alginate micro-beads added as crosslinkers. The gels have been evaluated in light of the amount of Ca(2+) added to the alginate solution, and in light of the different dimensions of the micro-beads, using rheological measurements to assess the variation in the storage modulus (G'), loss modulus (G'') and complex viscosity (η(*)) as well as swelling and deswelling tests. The methodology was developed to obtain a material with specific characteristics for application in the field of conservation. The material had to be able to create a stable gel after being applied on the artwork surface and to confine the solvent action at the interface during cleaning operations.

  14. A novel strategy for the preparation of porous microspheres and its application in peptide drug loading.

    PubMed

    Wei, Yi; Wang, Yuxia; Zhang, Huixia; Zhou, Weiqing; Ma, Guanghui

    2016-09-15

    A new strategy is developed to prepare porous microspheres with narrow size distribution for peptides controlled release, involving a fabrication of porous microspheres without any porogens followed by a pore closing process. Amphiphilic polymers with different hydrophobic segments (poly(monomethoxypolyethylene glycol-co-d,l-lactide) (mPEG-PLA), poly(monomethoxypolyethylene glycol-co-d,l-lactic-co-glycolic acid) (mPEG-PLGA)) are employed as microspheres matrix to prepare porous microspheres based on a double emulsion-premix membrane emulsification technique combined with a solvent evaporation method. Both microspheres possess narrow size distribution and porous surface, which are mainly caused by (a) hydrophilic polyethylene glycol (PEG) segments absorbing water molecules followed by a water evaporation process and (b) local explosion of microspheres due to fast evaporation of dichloromethane (MC). Importantly, mPEG-PLGA microspheres have a honeycomb like structure while mPEG-PLA microspheres have a solid structure internally, illustrating that the different hydrophobic segments could modulate the affinity between solvent and matrix polymer and influence the phase separation rate of microspheres matrix. Long term release patterns are demonstrated with pore-closed microspheres, which are prepared from mPEG-PLGA microspheres loading salmon calcitonin (SCT). These results suggest that it is potential to construct porous microspheres for drug sustained release using permanent geometric templates as new porogens.

  15. Drug release behavior of poly (lactic-glycolic acid) grafting from sodium alginate (ALG-g-PLGA) prepared by direct polycondensation.

    PubMed

    Shi, Gang; Ding, Yuanyuan; Zhang, Xin; Wu, Luyan; He, Fei; Ni, Caihua

    2015-01-01

    Hydrophobically modified sodium alginate, poly (lactic-glycolic acid) grafting from sodium alginate (ALG-g-PLGA), was successfully synthesized through direct one-step polymerization of sodium alginate, glycolic acid, and lactic acid. ALG-g-PLGA self-assembled to colloidal nanoparticles and subsequently hydrogel microspheres were obtained by crosslinking ALG-g-PLGA nanoparticles in the solution of calcium chloride. The modified hydrogel microspheres could be used as the drug delivery vehicles for a hydrophobic ibuprofen. Compared with sodium alginate, ALG-g-PLGA demonstrated an improved drug loading rate, encapsulation efficiency, and prolonged release speed. The products, as novel and highly promising biomaterials, have potential applications.

  16. Evaluation of enteric matrix microspheres prepared by emulsion-solvent evaporation using scanning electron microscopy.

    PubMed

    Obeidat, W M; Price, J C

    2004-02-01

    Theophylline microspheres were prepared by the emulsion-solvent evaporation method using cellulose acetate butyrate (CAB381-20) and mixtures of CAB381-20(R) and cellulose acetate phthalate. The physical state of the drug, polymers and microspheres surfaces were determined using scanning electron microscopy. For those microspheres prepared using mixtures of CAB381-20 and cellulose acetate phthalate, scanning electron micrographs were taken before dissolution and also at different stages of dissolution (in SGF, pH 1.2 and in simulated intestinal fluid, pH 7.5). Micrographs were taken of the outside surfaces of the microspheres and of the cleaved microspheres showing their interiors (core). Drug crystals were observed on or near the surface of microspheres prepared from the polymer mixtures, while no drug particles or crystals were seen on the surfaces of microspheres prepared solely from CAB381-20. An acid wash for less than 2 min was capable of extracting all drug on the surface of the microspheres prepared from a mixture of CAB381-20 and cellulose acetate phthalate. The absence of drug crystals on the surface of CAB381-20 microspheres is believed to prevent initial drug release and create a lag time in release profiles. Results suggest that in both microsphere formulations, a layer of drug-free polymer is formed outside the core matrix and is believed to be responsible for the near zero-order release profiles.

  17. Injectable alginate/hydroxyapatite gel scaffold combined with gelatin microspheres for drug delivery and bone tissue engineering.

    PubMed

    Yan, Jingxuan; Miao, Yuting; Tan, Huaping; Zhou, Tianle; Ling, Zhonghua; Chen, Yong; Xing, Xiaodong; Hu, Xiaohong

    2016-06-01

    Injectable and biodegradable alginate-based composite gel scaffolds doubly integrated with hydroxyapatite (HAp) and gelatin microspheres (GMs) were cross-linked via in situ release of calcium cations. As triggers of calcium cations, CaCO3 and glucono-D-lactone (GDL) were fixed as a mass ratio of 1:1 to control pH value ranging from 6.8 to 7.2 during gelation. Synchronously, tetracycline hydrochloride (TH) was encapsulated into GMs to enhance bioactivity of composite gel scaffolds. The effects of HAp and GMs on characteristics of gel scaffolds, including pH value, gelation time, mechanical properties, swelling ratio, degradation behavior and drug release, were investigated. The results showed that HAp and GMs successfully improved mechanical properties of gel scaffolds at strain from 0.1 to 0.5, which stabilized the gel network and decreased weight loss, as well as swelling ratio and gelation time. TH could be released from this composite gel scaffold into the local microenvironment in a controlled fashion by the organic/inorganic hybrid of hydrogel network. Our results demonstrate that the HAp and GMs doubly integrated alginate-based gel scaffolds, especially the one with 6% (w/v) HAp and 5% (w/v) GMs, have suitable physical performance and bioactive properties, thus provide a potential opportunity to be used for bone tissue engineering. The potential application of this gel scaffold in bone tissue engineering was confirmed by encapsulation behavior of osteoblasts. In combination with TH, the gel scaffold exhibited beneficial effects on osteoblast activity, which suggested a promising future for local treatment of pathologies involving bone loss.

  18. Facile fabrication of poly(L-lactic acid) microsphere-incorporated calcium alginate/hydroxyapatite porous scaffolds based on Pickering emulsion templates.

    PubMed

    Hu, Yang; Ma, Shanshan; Yang, Zhuohong; Zhou, Wuyi; Du, Zhengshan; Huang, Jian; Yi, Huan; Wang, Chaoyang

    2016-04-01

    In this study, we develop a facile one-pot approach to the fabrication of poly(L-lactic acid) (PLLA) microsphere-incorporated calcium alginate (ALG-Ca)/hydroxyapatite (HAp) porous scaffolds based on HAp nanoparticle-stabilized oil-in-water Pickering emulsion templates, which contain alginate in the aqueous phase and PLLA in the oil phase. The emulsion aqueous phase is solidified by in situ gelation of alginate with Ca(2+) released from HAp by decreasing pH with slow hydrolysis of D-gluconic acid δ-lactone (GDL) to produce emulsion droplet-incorporated gels, followed by freeze-drying to form porous scaffolds containing microspheres. The pore structure of porous scaffolds can be adjusted by varying the HAp or GDL concentration. The compressive tests show that the increase of HAp or GDL concentration is beneficial to improve the compressive property of porous scaffolds, while the excessive HAp can lead to the decrease in compressive property. Moreover, the swelling behavior studies display that the swelling ratios of porous scaffolds reduce with increasing HAp or GDL concentration. Furthermore, hydrophobic drug ibuprofen (IBU) and hydrophilic drug bovine serum albumin (BSA) are loaded into the microspheres and scaffold matrix, respectively. In vitro drug release results indicate that BSA has a rapid release while IBU has a sustained release in the dual drug-loaded scaffolds. In vitro cell culture experiments verify that mouse bone mesenchymal stem cells can proliferate on the porous scaffolds well, indicating the good biocompatibility of porous scaffolds. All these results demonstrate that the PLLA microsphere-incorporated ALG-Ca/HAp porous scaffolds have a promising potential for tissue engineering and drug delivery applications.

  19. Preparation of carbon nanotube-alginate nanocomposite gel for tissue engineering.

    PubMed

    Kawaguchi, Minoru; Fukushima, Tadao; Hayakawa, Toru; Nakashima, Naotoshi; Inoue, Yusuke; Takeda, Shoji; Okamura, Kazuhiko; Taniguchi, Kunihisa

    2006-12-01

    A novel scaffold material based on an alginate hydrogel which contained carbon nanotubes (CNTs) was prepared, and its mechanical property and biocompatibility evaluated. Soluble CNTs were prepared with acid treatment and dispersed in sodium alginate solution as a cross-linker. After which, the mechanical property (elastic deformation), saline sorption, histological reaction, and cell viability of the resultant nanocomposite gel (CNT-Alg gel) were evaluated. The CNT-Alg gel showed faster gelling and higher mechanical strength than the conventional alginate gel. Saline sorption amount of freeze-dried CNT-Alg gel was equal to that of the alginate gel. In terms of histological evaluation and cell viability assay, CNT-Alg gel exhibited a mild inflammatory response and non-cytotoxicity. These results thus suggested that CNT-Alg gel could be useful as a scaffold material in tissue engineering with the sidewalls of CNTs acting as active sites for chemical functionalization.

  20. Preparation and In vitro / In vivo characterization of spray dried microsphere formulation encapsulating 4-chlorocurcumin

    PubMed Central

    Gogu, P. K.; Jithan, A. V.

    2010-01-01

    The objective of the present study was to prepare and characterize in vitro and in vivo performance of a sustained release microsphere formulation of 4-chlorocurcumin, a novel curcumin analogue. A spray dried technique with ethylcellulose as the polymer was used in the preparation of these microspheres. Microspheres were characterized for drug content, particle size and shape, in vitro drug release and the drug-polymer interaction. To assess in vivo performance, both pharmacokinetics and hepatoprotective activity were investigated. Results were compared with an equivalent i.v. solution. The microspheres of 4-chlorocurcumin with ethylcellulose were successfully prepared using a spray-dried technique. These microspheres were able to sustain the release of the drug both in vitro as well as in vivo. Microspheres offered better pharmacokinetic and hepatoprotective properties to the drug compared to its solution form. PMID:21188044

  1. Preparation and structure of drug-carrying biodegradable microspheres designed for transarterial chemoembolization therapy.

    PubMed

    Wang, Yujing; Benzina, Abderazak; Molin, Daniel G M; Akker, Nynke van den; Gagliardi, Mick; Koole, Leo H

    2015-01-01

    Biodegradable poly(D,L-lactic acid) drug-eluting microspheres containing anti-tumor drugs, cisplatin, and sorafenib tosylate have been prepared by the emulsion solvent evaporation method with diameter between 200 and 400 μm. Scanning electron microscopy showed that cisplatin microspheres had smooth surfaces, while sorafenib tosylate microspheres and cisplatin + sorafenib tosylate microspheres were porous at the surface and the pits of the latter were larger than those of the former. Notably, cisplatin + sorafenib tosylate microspheres had a fast drug release rate compared with microspheres containing one drug alone. In vitro cytotoxicity experiments and classical matrigel endothelial tube assay certificated the maintaining bioactivity of cisplatin and sorafenib tosylate released from the microspheres, respectively. This work provides a useful approach for the fabrication of drug-eluting beads used in transarterial chemoembolization.

  2. Preparation of PVA/amino multi-walled carbon nanotubes nanocomposite microspheres for endotoxin adsorption.

    PubMed

    Zong, Wenhui; Chen, Jian; Han, Wenyan; Cheng, Guanghui; Chen, Jie; Wang, Yue; Wang, Weichao; Ou, Lailiang; Yu, Yaoting; Shen, Jie

    2017-03-23

    A novel polyvinyl alcohol-amino multi-walled carbon nanotube (PVA-AMWCNT) nanocomposite microsphere was prepared successfully for the first time and used for endotoxin removal. The resulting AMWCNT modified PVA microsphere was characterized by SEM, Raman spectrum and fluorescence image, which indicated AMWCNT was dispersed into the macropores of PVA microsphere uniformly. The PVA-AMWCNT microspheres showed better adsorption capability and faster adsorption equilibrium for endotoxin in aqueous solution when compared to the PVA microsphere with polymyxin B (PMB) as ligand. More noteworthy, the PVA based microspheres had little nonspecific adsorption in simulated serum. Therefore, PVA-AMWCNT nanocomposite microsphere with an excellent haemocompatibility has a great potential application in clinical blood purification.

  3. Preparation of alginate hydrogels through solution extrusion and the release behavior of different drugs.

    PubMed

    Liu, Guiting; Zhou, Hongxun; Wu, Hong; Chen, Rong; Guo, Shaoyun

    2016-10-07

    Homogeneous alginate hydrogels were facilely fabricated through solution extrusion process. CaCO3 and D-glucono-δ-lactone (GDL) were used as the gelation agents. The slow gelation of alginate was realized by the in-situ release of Ca(2+) from CaCO3 particles induced by hydrolysis of GDL to reduce pH. Slight gelation during the extrusion caused the enhanced strength of the alginate solutions, leading to the extrudability of the blends. This method enables to produce alginate hydrogels in a single step via extrusion, which is economically advantageous to conventional lab-scale preparation for mass production. Three different drugs, ibuprofen, acetaminophen, and methylthionine chloride, were used as model drugs to evaluate the drug release behavior of the alginate hydrogels. It was demonstrated that the drug release behavior was significantly adjusted by both the drug solubility and the ionic interaction between alginate and the drug molecule. It was shown that solution extrusion process is a feasible method to produce alginate-based drug delivery systems.

  4. Alginate Hydrogel: A Shapeable and Versatile Platform for in Situ Preparation of Metal-Organic Framework-Polymer Composites.

    PubMed

    Zhu, He; Zhang, Qi; Zhu, Shiping

    2016-07-13

    This work reports a novel in situ growth approach for incorporating metal-organic framework (MOF) materials into an alginate substrate, which overcomes the challenges of processing MOF particles into specially shaped structures for real industrial applications. The MOF-alginate composites are prepared through the post-treatment of a metal ion cross-linked alginate hydrogel with a MOF ligand solution. MOF particles are well distributed and embedded in and on the surface of the composites. The macroscopic shape of the composite can be designed by controlling the shape of the corresponding hydrogel; thus MOF-alginate beads, fibers, and membranes are obtained. In addition, four different MOF-alginate composites, including HKUST-1-, ZIF-8-, MIL-100(Fe)-, and ZIF-67-alginate, were successfully prepared using different metal ion cross-linked alginate hydrogels. The mechanism of formation is revealed, and the composite is demonstrated to be an effective absorbent for water purification.

  5. Preparation, characterization and in vitro release of gentamicin from PHBV/wollastonite composite microspheres.

    PubMed

    Li, Haiyan; Chang, Jiang

    2005-10-20

    Composite microspheres have been prepared from bioactive wollastonite (W) and biodegradable poly (hydroxybutyrate-polyhydroxyvalerate) (PHBV) in the present study. Gentamicin was encapsulated into the microspheres by the absorption method and the in vitro release of the gentamicin from the microspheres was performed in distilled water, modified simulated body fluid (SBF) and phosphate buffered saline (PBS) at 37 degrees C for 22 days, respectively. The results showed that the release behavior of gentamicin from PHBV/W composite microspheres was similar to that from the pure PHBV microspheres when the experiment was performed in distilled water. However, in the PBS and SBF solutions, gentamicin released from the PHBV/W composite microspheres at a relatively lower rate as compared to that of the pure PHBV microspheres and 90% of the total amount of gentamicin released from the composite microspheres after soaking for 22 days, which was much longer than that for the release of the same amount gentamicin from the pure PHBV microspheres (8 days). Scanning electron microscopy (SEM) and energy-dispersive spectrometer (EDS) analysis on the microspheres after release in SBF and PBS revealed that a microporous apatite layer was formed on the composite microspheres surface, which resulted in a controlled release behavior of the gentamicin from the PHBV/W composite microspheres. All of these results provided the possibility that the PHBV/W composite microspheres could be applied as alternative drug controlled release systems, especially as bone fillings for bone repair due to their advantages of controlled releasing antibiotics and apatite-formation ability, through which the implanted microspheres could chemically bond to the surrounding tissue in vivo.

  6. Preparation of PLLA/bpV(pic) microspheres and their effect on nerve cells.

    PubMed

    Lin, Qiang; Chen, Hai-yun; Li, Hao-shen; Cai, Yang-ting

    2014-02-01

    In this study, we prepared PLLA/bpV(pic) microspheres, a bpV(pic) controlled release system and examined their ability to protect nerve cells and promote axonal growth. PLLA microspheres were prepared by employing the o/w single emulsification-evaporation technique. Neural stem cells and dorsal root ganglia were divided into 3 groups in terms of the treatment they received: a routine medium group (cultured in DMEM), a PLLA microsphere group (DMEM containing PLLA microspheres alone) and a PLLA/bpV(pic) group [DMEM containing PLLA/bpV(pic) microspheres]. The effects of PLLA/bpV(pic) microspheres were evaluated by the live-dead test and measurement of axonal length. Our results showed that PLLA/bpV(pic) granulation rate was (88.2±5.6)%; particle size was (16.8±3.1)%, drug loading was (4.05±0.3)%; encapsulation efficiency was (48.5±1.8)%. The release time lasted for 30 days. In PLLA/bpV(pic) microsphere group, the cell survival rate was (95.2 ±4.77)%, and the length of dorsal root ganglion (DRG) was 718±95 μm, which were all significantly greater than those in ordinary routine medium group and PLLA microsphere group. This preliminary test results showed the PLLA/bpV(pic) microspheres were successfully prepared and they could promote the survival and growth of neural cells in DRG.

  7. Microspheres

    NASA Technical Reports Server (NTRS)

    1990-01-01

    Vital information on a person's physical condition can be obtained by identifying and counting the population of T-cells and B-cells, lymphocytes of the same shape and size that help the immune system protect the body from the invasion of disease. The late Dr. Alan Rembaum developed a method for identifying the cells. The method involved tagging the T-cells and B-cells with microspheres of different fluorescent color. Microspheres, which have fluorescent dye embedded in them, are chemically treated so that they can link with antibodies. With the help of a complex antibody/antigen reaction, the microspheres bind themselves to specific 'targets,' in this case the T-cells or B-cells. Each group of cells can then be analyzed by a photoelectronic instrument at different wavelengths emitted by the fluorescent dyes. Same concept was applied to the separation of cancer cells from normal cells. Microspheres were also used to conduct many other research projects. Under a patent license Magsphere, Inc. is producing a wide spectrum of microspheres on a large scale and selling them worldwide for various applications.

  8. Preparation, structure, and in vitro chemical durability of yttrium phosphate microspheres for intra-arterial radiotherapy.

    PubMed

    Kawashita, Masakazu; Matsui, Naoko; Li, Zhixia; Miyazaki, Toshiki; Kanetaka, Hiroyasu

    2011-10-01

    Chemically durable microspheres containing yttrium and/or phosphorus are useful for intra-arterial radiotherapy. In this study, we attempted to prepare yttrium phosphate (YPO₄) microspheres with high chemical durability. YPO₄ microspheres with smooth surfaces and diameters of around 25 μm were successfully obtained when gelatin droplets containing yttrium and phosphate ions were cooled and solidified in a water-in-oil emulsion and then heat-treated at 1100°C. The chemical durability of the heat-treated microspheres in a simulated body fluid at pH = 6 and 7 was high enough for clinical application of intra-arterial radiotherapy.

  9. Chitosan-based Floating Microspheres of Trimetazidin Dihydrochloride; Preparation and In vitro Characterization

    PubMed Central

    El-Nahas, H. M.; Hosny, K. M.

    2011-01-01

    The aim of present study involves preparation and characterization of floating microspheres using trimetazidin dihydrochloride as a model drug to increase the residence time in the stomach without contact with the mucosa, Floating microspheres were prepared by the capillary extrusion technique using chitosan as polymer and sodium lauryl sulphate as cross linking agent. The surface morphology of the prepared microspheres was characterized by the optical microscopic method. The effect of the stirring rate during preparation, polymer concentration and cross linking concentration on the percent yield, in vitro floating behavior, physical state of the incorporated drug, drug loading and in vitro drug release were studied. The prepared microspheres exhibited prolonged drug release (12 h) and remained buoyant for more than 11 h. The microspheres were found to be regular in shape and highly porous. The trimetazidin dihydrochloride release rate was higher in the case of microspheres prepared at a higher agitation speed and decreased with increasing the polymer and cross linking agent concentration. All formulations demonstrated favorable in vitro floating characteristics. The drug entrapment increased from 65.13 to 85.3% with increasing polymer to drug ratio. Diffusion was found to be the main release mechanism. Thus, the prepared floating microspheres may prove to be potential candidates for multiple-unit delivery devices adaptable to any intragastric conditions. PMID:22707823

  10. Ultrasonic atomization for spray drying: a versatile technique for the preparation of protein loaded biodegradable microspheres.

    PubMed

    Bittner, B; Kissel, T

    1999-01-01

    Bovine serum albumin (BDA) loaded microspheres with a spherical shape and smooth surface structure were successfully prepared from poly(lactide-co-glycolide) using an ultrasonic nozzle installed in a Niro laboratory spray dryer. Process and formulation parameters were investigated with respect to their influence on microsphere characteristics, such as particle size, loading capacity, and release properties. Preparation of microspheres in yields of more than 50% was achieved using an ultrasonic atomizer connected to a stream of carrier air. Microsphere characteristics could be modified by changing several technological parameters. An increased polymer concentration of the feed generated larger particles with a significantly reduced initial release of the protein. Moreover, microspheres with a smooth surface structure were obtained from the organic polymer solution with the highest viscosity. Microparticles with a low BSA loading showed a large central cavity surrounded by a thin polymer layer in scanning electron microspheres. A high protein loading led to an enlargement of the shell layer, or even to dense particles without any cavities. A continuous in vitro release pattern of BSA was obtained from the particles with low protein loading. Glass transition temperatures (Tg) of the microspheres before and after lyophilization did not differ from those of the BSA loaded particles prepared by spray drying with a rotary atomizer. Analysis of the polymer by gel permeation chromatography indicated that ultrasonication had no effect on polymer molecular weight. Molecular weight and polydispersity of the pure polymer, placebo microspheres prepared by spray drying, and placebo microspheres prepared using the ultrasonic nozzle were in the same range. In conclusion, ultrasonic atomization represents a versatile and reliable technique for the production of protein loaded biodegradable microspheres without inducing a degradation of the polymer matrix. Particle characteristics

  11. Enhanced oral bioavailability of salmeterol by loaded PLGA microspheres: preparation, in vitro, and in vivo evaluation.

    PubMed

    Zhang, Haiping; Xu, Jianfang

    2016-01-01

    The objective of the current study was to prepare microspheres of salmeterol (SM) using poly (lactide-co-glycolide) (PLGA) and assess its viability to enhance the oral bioavailability. Microspheres of SM were prepared by oil-in-water emulsion-solvent evaporation method. The formulations were characterized in encapsulation efficiency, particle size, zeta potential, and in vitro release. The prepared microspheres were found to be spherical in shape with smooth surface. The size of microspheres ranged from 14.7 to 16.5 µm. The polydispersity index (PDI) was 0.12 ± 0.05 and the zeta potential was -33.2 ± 1.4 mV. In vitro release profile, SM was graduated released from the microspheres as time lapsed, suggesting that SM was well entrapped in SM-loaded PLGA microspheres. The model that fitted best for SM released from the microspheres was Higuchi equation. In vivo study, SM-loaded PLGA microspheres are thought to have the potential to maintain SM concentration within target ranges for a long time, decreasing side effects caused by concentration fluctuation, ensuring the efficiency of treatment and improving patient compliance by reducing dosing frequency.

  12. Preparation and characterization of alginate-gelatin microencapsulated Bacillus subtilis SL-13 by emulsification/internal gelation.

    PubMed

    Tu, Liang; He, Yanhui; Yang, Hongbing; Wu, Zhansheng; Yi, Lijuan

    2015-01-01

    Gelatin was blended with sodium alginate (NaALG) to obtain a novel microbial fungicide, and dispersed micron Bacillus subtilis SL-13 microspheres prepared by emulsification/internal gelation method. Microscopic examination revealed that microcapsules were nearly spherical in shape. Fourier transform infrared spectroscopy, differential scanning calorimetry, and X-ray diffraction confirmed that the electrostatic interaction was occurred when gelatin added into NaALG. The maximum encapsulation efficiency was 93.44% at a gelatin concentration of 1.5%. Particle size, swelling, and biodegradation of beads increased with gelatin content increase. Furthermore, the viability of encapsulated SL-13 could be preserved at more than 10(8) CFU/mL after 120 d storage at 25 °C. The number of viable cells released from microcapsules presented an initial rapid increase followed by a gradual increase, and reached the maximum as 10(10) CFU/mL on day 35. Thus, it is feasible to prepare uniform, rounded shape, and well-dispersed micron microcapsules of SL-13 via emulsification/internal gelation using NaALG and gelatin composites. This encapsulation strategy could be considered as a potential alternative to future applications in the agricultural industry.

  13. Facile preparation of multifunctional superparamagnetic PHBV microspheres containing SPIONs for biomedical applications

    NASA Astrophysics Data System (ADS)

    Li, Wei; Jan Zaloga; Ding, Yaping; Liu, Yufang; Janko, Christina; Pischetsrieder, Monika; Alexiou, Christoph; Boccaccini, Aldo R.

    2016-03-01

    The promising potential of magnetic polymer microspheres in various biomedical applications has been frequently reported. However, the surface hydrophilicity of superparamagnetic iron oxide nanoparticles (SPIONs) usually leads to poor or even failed encapsulation of SPIONs in hydrophobic polymer microspheres using the emulsion method. In this study, the stability of SPIONs in poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) solution was significantly increased after surface modification with lauric acid. As a result, magnetic PHBV microspheres with high encapsulation efficiencies (71.0–87.4%) were prepared using emulsion-solvent extraction/evaporation method. Magnetic resonance imaging (MRI) showed significant contrast for the magnetic PHBV microspheres. The toxicity of these magnetic PHBV microspheres towards human T-lymphoma suspension cells and adherent colon carcinoma HT-29 cells was investigated using flow cytometry, and they were shown to be non-toxic in a broad concentration range. A model drug, tetracycline hydrochloride, was used to demonstrate the drug delivery capability and to investigate the drug release behavior of the magnetic PHBV microspheres. The drug was successfully loaded into the microspheres using lauric acid-coated SPIONs as drug carrier, and was released from the microspheres in a diffusion controlled manner. The developed magnetic PHBV microspheres are promising candidates for biomedical applications such as targeted drug delivery and MRI.

  14. Facile preparation of multifunctional superparamagnetic PHBV microspheres containing SPIONs for biomedical applications

    PubMed Central

    Li, Wei; Jan Zaloga; Ding, Yaping; Liu, Yufang; Janko, Christina; Pischetsrieder, Monika; Alexiou, Christoph; Boccaccini, Aldo R.

    2016-01-01

    The promising potential of magnetic polymer microspheres in various biomedical applications has been frequently reported. However, the surface hydrophilicity of superparamagnetic iron oxide nanoparticles (SPIONs) usually leads to poor or even failed encapsulation of SPIONs in hydrophobic polymer microspheres using the emulsion method. In this study, the stability of SPIONs in poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) solution was significantly increased after surface modification with lauric acid. As a result, magnetic PHBV microspheres with high encapsulation efficiencies (71.0–87.4%) were prepared using emulsion-solvent extraction/evaporation method. Magnetic resonance imaging (MRI) showed significant contrast for the magnetic PHBV microspheres. The toxicity of these magnetic PHBV microspheres towards human T-lymphoma suspension cells and adherent colon carcinoma HT-29 cells was investigated using flow cytometry, and they were shown to be non-toxic in a broad concentration range. A model drug, tetracycline hydrochloride, was used to demonstrate the drug delivery capability and to investigate the drug release behavior of the magnetic PHBV microspheres. The drug was successfully loaded into the microspheres using lauric acid-coated SPIONs as drug carrier, and was released from the microspheres in a diffusion controlled manner. The developed magnetic PHBV microspheres are promising candidates for biomedical applications such as targeted drug delivery and MRI. PMID:27005428

  15. Facile preparation of multifunctional superparamagnetic PHBV microspheres containing SPIONs for biomedical applications.

    PubMed

    Li, Wei; Jan Zaloga; Ding, Yaping; Liu, Yufang; Janko, Christina; Pischetsrieder, Monika; Alexiou, Christoph; Boccaccini, Aldo R

    2016-03-23

    The promising potential of magnetic polymer microspheres in various biomedical applications has been frequently reported. However, the surface hydrophilicity of superparamagnetic iron oxide nanoparticles (SPIONs) usually leads to poor or even failed encapsulation of SPIONs in hydrophobic polymer microspheres using the emulsion method. In this study, the stability of SPIONs in poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) solution was significantly increased after surface modification with lauric acid. As a result, magnetic PHBV microspheres with high encapsulation efficiencies (71.0-87.4%) were prepared using emulsion-solvent extraction/evaporation method. Magnetic resonance imaging (MRI) showed significant contrast for the magnetic PHBV microspheres. The toxicity of these magnetic PHBV microspheres towards human T-lymphoma suspension cells and adherent colon carcinoma HT-29 cells was investigated using flow cytometry, and they were shown to be non-toxic in a broad concentration range. A model drug, tetracycline hydrochloride, was used to demonstrate the drug delivery capability and to investigate the drug release behavior of the magnetic PHBV microspheres. The drug was successfully loaded into the microspheres using lauric acid-coated SPIONs as drug carrier, and was released from the microspheres in a diffusion controlled manner. The developed magnetic PHBV microspheres are promising candidates for biomedical applications such as targeted drug delivery and MRI.

  16. Liraglutide-loaded poly(lactic-co-glycolic acid) microspheres: Preparation and in vivo evaluation.

    PubMed

    Wu, Junzi; Williams, Gareth R; Branford-White, Christopher; Li, Heyu; Li, Yan; Zhu, Li-Min

    2016-09-20

    In this work, we sought to generate sustained-release injectable microspheres loaded with the GLP-1 analogue liraglutide. Using water-in-oil-in-water double emulsion methods, poly(lactic-co-glycolic acid) (PLGA) microspheres loaded with liraglutide were prepared. The microspheres gave sustained drug release over 30days, with cumulative release of up to 90% reached in vitro. The microspheres were further studied in a rat model of diabetes, and their performance compared with a group given daily liraglutide injections. Reduced blood sugar levels were seen in the microsphere treatment groups, with the results being similar to those obtained with conventional injections between 10 and 25days after the commencement of treatment. After 5 and 30days of treatment, the microspheres seem a little slower to act than the injections. The pathology of the rats' spleen, heart, kidney and lungs was probed after the 30-day treatment period, and the results indicated that the microspheres were safe and had beneficial effects on the liver, reducing the occurrence of fatty deposits seen in untreated diabetic rats. Moreover, in terms of liver, renal and cardiac functions, and blood lipid and antioxidant levels, the microspheres were as effective as the injections. The expression of several proteases linked to the metabolism of aliphatic acids and homocysteine was promoted by the microsphere formulations. Inflammatory markers in the microsphere treatment groups were somewhat higher than the injection group, however. The liraglutide/PLGA microspheres prepared in this work are overall shown to be efficacious in a rat model of diabetes, and we thus believe they have strong potential for clinical use.

  17. Preparation and characterization of alginate and psyllium beads containing Lactobacillus acidophilus.

    PubMed

    Lotfipour, Farzaneh; Mirzaeei, Shahla; Maghsoodi, Maryam

    2012-01-01

    This paper describes preparation and characterization of beads of alginate and psyllium containing probiotic bacteria of Lactobacillus acidophilus DMSZ20079. Twelve different formulations containing alginate (ALG) and alginate-psyllium (ALG-PSL) were prepared using extrusion technique. The prepared beads were characterized in terms of size, morphology and surface properties, encapsulation efficiency, viabilities in acid (pH 1.8, 2 hours) and bile (0.5% w/v, 2 hours) conditions, and release in simulated colon pH conditions. The results showed that spherical beads with narrow size distribution ranging from 1.59 ± 0.04 to 1.67 ± 0.09 mm for ALG and from 1.61 ± 0.06 to 1.80 ± 0.07 mm for ALG-PSL with encapsulation efficiency higher than 98% were achieved. Furthermore, addition of PSL into ALG enhanced the integrity of prepared beads in comparison with ALG formulations. The results indicated that incorporation of PSL into alginate beads improved viability of the bacteria in acidic conditions as well as bile conditions. Also, stimulating effect of PSL on the probiotic bacteria was observed through 20-hour incubation in simulated colonic pH solution. According to our in vitro studies, PSL can be a suitable polymer candidate for partial substitution with ALG for probiotic coating.

  18. Preparation and Characterization of Alginate and Psyllium Beads Containing Lactobacillus acidophilus

    PubMed Central

    Lotfipour, Farzaneh; Mirzaeei, Shahla; Maghsoodi, Maryam

    2012-01-01

    This paper describes preparation and characterization of beads of alginate and psyllium containing probiotic bacteria of Lactobacillus acidophilus DMSZ20079. Twelve different formulations containing alginate (ALG) and alginate-psyllium (ALG-PSL) were prepared using extrusion technique. The prepared beads were characterized in terms of size, morphology and surface properties, encapsulation efficiency, viabilities in acid (pH 1.8, 2 hours) and bile (0.5% w/v, 2 hours) conditions, and release in simulated colon pH conditions. The results showed that spherical beads with narrow size distribution ranging from 1.59 ± 0.04 to 1.67 ± 0.09 mm for ALG and from 1.61 ± 0.06 to 1.80 ± 0.07 mm for ALG-PSL with encapsulation efficiency higher than 98% were achieved. Furthermore, addition of PSL into ALG enhanced the integrity of prepared beads in comparison with ALG formulations. The results indicated that incorporation of PSL into alginate beads improved viability of the bacteria in acidic conditions as well as bile conditions. Also, stimulating effect of PSL on the probiotic bacteria was observed through 20-hour incubation in simulated colonic pH solution. According to our in vitro studies, PSL can be a suitable polymer candidate for partial substitution with ALG for probiotic coating. PMID:22649306

  19. Preparation and adsorption properties of magnetic CoFe2O4-chitosan composite microspheres

    NASA Astrophysics Data System (ADS)

    Lian, Qi; Zheng, Xue-Fang; Hu, Tie-Feng

    2015-11-01

    Magnetic chitosan microspheres made from novel polymer materials show outstanding applied characteristics. Magnetic chitosan microspheres are rather cheap, non-toxic, tasteless, alkali resistant, corrosion resistant, easily degradable, easily recyclable, and so on. It can be widely used in many fields. In this paper, magnetic CoFe2O4/chitosan core-shell microspheres are prepared by means of emulsification cross-linking technique using CoFe2O4 as core and glutaric dialdehyde as crosslinking agent. The results demonstrated that the different calcining temperature of magnetic (CoFe2O4) particles, CoFe2O4/chitosan ratio and stirring time of the suspension medium are the most effective parameters that control the size, size distribution, morphology and magnetism of the described microspheres. Finally, the size, morphology and chemical structure of the prepared materials are studied by different methods. The results show that the optimal calcination temperature of magnetic particles is 700°C, the optimal ratio of CoFe2O4/chitosan is 1: 1, ultrasonic dispersion time is 30 min. The prepared chitosan magnetic microspheres have small size and are well dispersed when the stirring time is 3 h. The prepared magnetic chitosan microspheres are well shaped spheres with a diameter from 1 to 50 μm, in which CoFe2O4 particles are dispersed uniformly. The magnetic chitosan microspheres show excellent magnetic response and have good adsorption characteristics.

  20. Cellulose acetate butyrate and polycaprolactone for ketoprofen spray-dried microsphere preparation.

    PubMed

    Giunchedi, P; Conti, B; Maggi, L; Conte, U

    1994-01-01

    Ketoprofen-loaded microspheres made with a polymeric blend were prepared by a spray-drying technique. Organic solutions of two polymers, cellulose acetate butyrate (CAB) and poly(epsilon-caprolactone) (PCL), in different weight ratios, and of ketoprofen (Ket) were prepared and sprayed, in different experimental conditions, achieving drug-loaded microspheres. The obtained spray-dried microspheres were characterized in terms of yield of production, shape, size, surface properties and drug content, and their in vitro drug release behaviours were determined at different pH values.

  1. Silk sericin loaded alginate nanoparticles: Preparation and anti-inflammatory efficacy.

    PubMed

    Khampieng, Thitikan; Aramwit, Pornanong; Supaphol, Pitt

    2015-09-01

    In this study, silk sericin loaded alginate nanoparticles were prepared by the emulsification method followed by internal crosslinking. The effects of various silk sericin loading concentration on particle size, shape, thermal properties, and release characteristics were investigated. The initial silk sericin loadings of 20, 40, and 80% w/w to polymer were incorporated into these alginate nanoparticles. SEM images showed a spherical shape and small particles of about 71.30-89.50 nm. TGA analysis showed that thermal stability slightly increased with increasing silk sericin loadings. FTIR analysis suggested interactions between alginate and silk sericin in the nanoparticles. The release study was performed in acetate buffer at normal skin conditions (pH 5.5; 32 °C). The release profiles of silk sericin exhibited initial rapid release, consequently with sustained release. These silk sericin loaded alginate nanoparticles were further incorporated into topical hydrogel and their anti-inflammatory properties were studied using carrageenan-induced paw edema assay. The current study confirms the hypothesis that the application of silk sericin loaded alginate nanoparticle gel can inhibit inflammation induced by carrageenan.

  2. A dry powder formulation from silk fibroin microspheres as a topical auto-gelling device.

    PubMed

    Faragò, Silvio; Lucconi, Giulia; Perteghella, Sara; Vigani, Barbara; Tripodo, Giuseppe; Sorrenti, Milena; Catenacci, Laura; Boschi, Alessandra; Faustini, Massimo; Vigo, Daniele; Chlapanidas, Theodora; Marazzi, Mario; Torre, Maria Luisa

    2016-01-01

    With the aim of establishing the formulation of a new hydrophilic auto-gelling medical device for biomedical applications, fibroin-based microspheres were prepared. The proposed microspheres were produced by a cost-effective and industrially scalable technique, such as the spray-drying. Spray-dried silk fibroin microspheres were obtained and the effects of different hydrophilic polymer on the process yield, microsphere morphology and conformation transition of fibroin were evaluated. The final auto-gelling formulations were obtained by adding calcium gluconate (as a calcium source for alginate crosslinking) to the prepared microspheres and tested by an in vitro gelling test. This study showed that the combination of fibroin with sodium alginate and poloxamer produced the most promising auto-gelling formulation for specific biomedical applications, such as the treatment of pressure ulcers.

  3. Preparation oral levofloxacin colon-specific microspheres delivery: in vitro and in vivo studies.

    PubMed

    Jin, Lei; Ding, Yicun; Feng, Mingli; Cao, Qin

    2016-01-01

    The aim of this study was to prepare levofloxacin-loaded chitosan microspheres and to evaluate their in vitro and in vivo characteristics. Glutaraldehyde-crosslinked microspheres were prepared using a spray-drying method, and characterized in terms of the morphological examination, particle size distribution, entrapment efficiency, drug loading and in vitro release. Pharmacokinetics and colon biodistribution studies were used to evaluate that microspheres have more advantage than the conventional formulations. The surface morphology of the freeze-dried microspheres were smooth, discrete with a regular spherical to near-spherical shape. Size of the microspheres after freeze-drying was 4.96 ± 0.76 μm and well-distributed. The zeta potential of microspheres was -29.3 ± 2.1 mV. An average drug loading of 9.3 ± 0.4% and encapsulation efficiency of 81.1 ± 4.7% of levofloxacin microspheres were obtained with the optimized preparation parameters. The cumulative release rate of levofloxacin microspheres was followed by a sustained release and fitted for classic Higuchi kinetic model. In vivo studies showed that chitosan microspheres are thought to have the potential to maintain levofloxacin concentration within target ranges for a long time, decreasing side effects caused by concentration fluctuation, ensuring the efficiency of treatment and improving patient compliance by reducing dosing frequency. It also does not cause any harmful or toxic effect in colon and rectum as evaluated by histopathologic studies.

  4. Preparation and characterization of alginate/silver/nicotinamide nanocomposites for treating diabetic wounds.

    PubMed

    Montaser, A S; Abdel-Mohsen, A M; Ramadan, M A; Sleem, A A; Sahffie, N M; Jancar, J; Hebeish, A

    2016-11-01

    Silver/Alginate/Nicotinamide nanoparticles composite (Ag/ALG/Nic) was prepared and used for the first time to fabricate wound dressing material. Sodium alginate (ALG) was used as reducing and stabilizing agents for preparation of silver nanoparticles (Ag-NPs). Effect of concentrations of alginate (ALG) on the particle size of silver were studied and confirmed by different techniques like UV/vis spectroscopy, transmission electron microscope (TEM) and dynamic light scattering (DLS). Nonwoven viscous fabrics were used as a carrier for silver/alginate/nanoparticles composite by impregnated the nonwoven fabrics as per the padding-curing technique. Nicotinamide (Nic) as anti-inflammatory drug was entrapped into Ag-NPS/ALG/nonwoven fabrics. Scanning electron microscope and energy dispersive x-ray (SEM-EDX) were used to evaluate the presence of Ag/ALG/Nic nanoparticles composite anchored the nonwoven fabrics. The antibacterial activity of the Ag/ALG/Nic wound dressing material was evaluated against Escherichia coli (E. coli) and Staphylococcus Aureus (St. Aureus). The wound healing and histological studied were evaluated by using burn diabetic rat animals.

  5. Preparation and properties of porous microspheres made from borate glass.

    PubMed

    Conzone, Samuel D; Day, Delbert E

    2009-02-01

    Dysprosium lithium-borate glass microspheres and particles, ranging from 45 to 150 microm in diameter, were reacted with a 0.25 M phosphate solution at 37 degrees C, whose pH was either 3 or 8.8. The glass reacted nonuniformly and was converted into a porous, amorphous, hydrated, dysprosium phosphate reaction product. The amorphous product had the same volume and shape (pseudomorphic) as the unreacted glass, and could be dried without cracking. After heating at 300 degrees C for 1 h, the amorphous reaction product had a specific surface area of approximately 200 m(2)/g, a pore size of approximately 30 nm, and nominal crushing strength of approximately 10 MPa. When the reaction product was heated to 600 degrees C for 15 min, the specific surface area decreased to approximately 90 m(2)/g and the nominal crushing strength increased to 35 MPa. Heating above 615 degrees C converted the amorphous dysprosium phosphate product into crystalline DyPO(4), which contained open porosity until heated above 800 degrees C for 15 min. Highly porous materials of different chemical composition can be prepared by chemically reacting a borate-based glass with an aqueous solution at low-temperature (<100 degrees C). These highly porous materials are easy to process, and are considered candidates for controlled drug delivery, catalysis, chromatographic separation, filtration, and as bioactive materials.

  6. Preparation and antibacterial property of silver decorated carbon microspheres

    NASA Astrophysics Data System (ADS)

    Li, Sha; Yan, Xiaoliang; Yang, Zhi; Yang, Yongzhen; Liu, Xuguang; Zou, Jing

    2014-02-01

    Carbon microspheres (CMSs) were prepared by glucose hydrothermal method. The effects of glucose concentration and reaction time on the size and morphology of CMSs were studied. CMSs with surface area of 642.5 m2/g and pore size of 0.8 nm were exploited to design hybrid material of CMSs with Ag decoration by radio frequency plasma (RF plasma). A series of investigations using X-ray diffraction, UV-vis spectrometry, Fourier transform infrared spectrometry, X-ray photoelectron spectrometry, thermogravimetric analysis, scanning electron microscopy, energy dispersive X-ray spectroscopy, and transmission electron microscopy was carried out to characterize the Ag decorated CMSs. RF plasma was employed to reduce Ag+ ions to metallic nano-particles with the particle size of 10-20 nm and form a clean metal-support (Ag-CMSs) interface. The mechanism for the structure formation of Ag decorated CMSs was discussed. Plasma produced Ag/CMSs showed antibacterial property and proved suitable for potential biological and environmental applications.

  7. Preparation and characterization of oxybenzone-loaded gelatin microspheres for enhancement of sunscreening efficacy.

    PubMed

    Patel, M; Jain, Sunil K; Yadav, Awesh K; Gogna, D; Agrawal, G P

    2006-01-01

    The objective of our present study was to prepare and evaluate gelatin microspheres of oxybenzone to enhance its sunscreening efficacy. The gelatin microspheres of oxybenzone were prepared by emulsion method. Process parameters were analyzed to optimize the formulation. The in vitro drug release study was performed in pH 7.4 using cellulose acetate membrane. Microspheres prepared using oxybenzone:gelatin ratio of 1:6 showed slowest drug release and those prepared with oxybenzone:gelatin ratio of 1:2 showed fastest drug release. The gelatin microspheres of oxybenzone were incorporated in aloe vera gel. Sun exposure method using sodium nitroprusside solution was used for in vitro sunscreen efficacy testing. The formulation C5 containing oxybenzone-bearing gelatin microspheres in aloe vera gel showed best sunscreen efficacy. The formulations were evaluated for skin irritation test in human volunteers, sun protection factor, and minimum erythema dose in albino rats. These studies revealed that the incorporation of sunscreening agent-loaded microspheres into aloe vera gel greatly increased the efficacy of sunscreen formulation more than four times.

  8. Preparation of hollow hydroxyapatite microspheres by the conversion of borate glass at near room temperature

    SciTech Connect

    Yao, Aihua; Ai, Fanrong; Liu, Xin; Wang, Deping; Huang, Wenhai; Xu, Wei

    2010-01-15

    Hollow hydroxyapatite microspheres, consisting of a hollow core and a porous shell, were prepared by converting Li{sub 2}O-CaO-B{sub 2}O{sub 3} glass microspheres in dilute phosphate solution at 37 {sup o}C. The results confirmed that Li{sub 2}O-CaO-B{sub 2}O{sub 3} glass was transformed to hydroxyapatite without changing the external shape and dimension of the original glass object. Scanning electron microscopy images showed the shell wall of the microsphere was built from hydroxyapatite particles, and these particles spontaneously align with one another to form a porous sphere with an interior cavity. Increase in phosphate concentration resulted in an increase in the reaction rate, which in turn had an effect on shell wall structure of the hollow hydroxyapatite microsphere. For the Li{sub 2}O-CaO-B{sub 2}O{sub 3} glass microspheres reacted in low-concentration K{sub 2}HPO{sub 4} solution, lower reaction rate and a multilayered microstructure were observed. On the other hand, the glass microspheres reacted in higher phosphate solution converted more rapidly and produced a single hydroxyapatite layer. Furthermore, the mechanism of forming hydroxyapatite hollow microsphere was described.

  9. Sustained release of risperidone from biodegradable microspheres prepared by in-situ suspension-evaporation process.

    PubMed

    An, Taekun; Choi, Juhyuen; Kim, Aram; Lee, Jin Ho; Nam, Yoonjin; Park, Junsung; Sun, Bo kyung; Suh, Hearan; Kim, Cherng-ju; Hwang, Sung-Joo

    2016-04-30

    Risperidone-loaded poly (D,L-lactide-co-glycolide) (PLGA) microspheres were prepared with a suspension-evaporation process with an aqueous suspension containing an in situ-formed aluminum hydroxide inorganic gel (SEP-AL process) and evaluated for encapsulation efficiency, particle size, surface morphology, glass transition temperature, in vitro drug release profile, and in vivo behavior. The SEP-AL microspheres were compared with conventional oil-in-water (O/W) emulsion solvent evaporation method using polyvinylalcohol (PVA) as an emulsifier (CP-PVA process). The microspheres were spherical in shape. DSC measurements showed that risperidone crystallinity was greatly reduced due to the homogeneous distribution of risperidone in PLGA microspheres. In vitro drug release profile from the microspheres showed a sigmoidal pattern of negligible initial burst up to 24h and minimal release (time-lag) for 7 days. After the lag phase, slow release took a place up to 25 days and then rapid release occurred sharply for 1 week. In vivo rat pharmacokinetic profile from the microspheres showed very low blood concentration level at the initial phase (up to 24h) followed by the latent phase up to 21 days. At the 3rd week, main phase started and the blood concentration of the drug increased up to the 5th week, and then gradually decreased. The risperidone-loaded PLGA microspheres produced by SEP-AL process showed excellent controlled release characteristics for the effective treatment of schizophrenia patients.

  10. Preparation of calcium alginate microgel beads in an electrodispersion reactor using an internal source of calcium carbonate nanoparticles.

    PubMed

    Zhao, Yinyan; Carvajal, M Teresa; Won, You-Yeon; Harris, Michael T

    2007-12-04

    An electrodispersion reactor has been used to prepare calcium alginate (Ca-alginate) microgel beads in this study. In the electrodispersion reactor, pulsed electric fields are utilized to atomize aqueous mixtures of sodium alginate and CaCO3 nanoparticles (dispersed phase) from a nozzle into an immiscible, insulating second liquid (continuous phase) containing a soluble organic acid. This technique combines the features of the electrohydrodynamic force driven emulsion processes and externally triggered gelations in microreactors (the droplets) ultimately to yield soft gel beads. The average particle size of the Ca-alginate gels generated by this method changed from 412 +/- 90 to 10 +/- 3 microm as the applied peak voltage was increased. A diagram depicting structural information for the Ca-alginate was constructed as a function of the concentrations of sodium alginate and CaCO3 nanoparticles. From this diagram, a critical concentration of sodium alginate required for sol-gel transformation was observed. The characteristic highly porous structure of Ca-alginate particles made by this technique appears suitable for microencapsulation applications. Finally, time scale analysis was performed for the electrodispersion processes that include reactions in the microreactor droplets to provide guidelines for the future employment of this technique. This electrodispersion reactor can be used potentially in the formation of many reaction-based microencapsulation systems.

  11. Preparation and functional evaluation of cell aggregates incorporating gelatin microspheres with different degradabilities.

    PubMed

    Tajima, Shuhei; Tabata, Yasuhiko

    2013-10-01

    The objective of this study was to investigate the viability and biological functions of cells in their aggregates incorporating gelatin microspheres with different degradabilities. After being prepared by a water-in-oil emulsion procedure, the gelatin microspheres were dehydrothermally crosslinked at 140°C for various time periods. In vitro degradation tests showed that the gelatin microspheres were slowly degraded slowly with an increase in the crosslinking time. When MC3T3-E1 cells were cultured with the gelatin hydrogel microspheres in the round U-bottom wells of 96-well microplates which had been coated with poly(vinyl alcohol), cell aggregates with homogeneously distributed gelatin microspheres were formed. A large amount of slowly degraded gelatin microspheres remained in the cell aggregates for long time periods, while a higher proliferation of MC3T3-E1 cells was observed. When evaluated as a measure of aerobic glycolysis, the ratio of l-lactic acid production:glucose consumption of MC3T3-E1 cells was lower for MC3T3-E1 cells in the cell aggregates incorporating slowly degraded gelatin microspheres than for aggregates incorporating rapidly degraded ones. The alkaline phosphatase activity and calcium content of MC3T3-E1 cells were higher for cell aggregates incorporating slowly degraded gelatin microspheres. It is possible that the incorporation of gelatin hydrogel microspheres with slow degradability enabled the permeation of oxygen and nutrients into the cell aggregates for longer time periods, resulting in better culture conditions for the survival, proliferation and differentiation of the cells.

  12. Preparation and characterization of genipin-cross-linked silk fibroin/chitosan sustained-release microspheres

    PubMed Central

    Zeng, Shuguang; Ye, Manwen; Qiu, Junqi; Fang, Wei; Rong, Mingdeng; Guo, Zehong; Gao, Wenfen

    2015-01-01

    We report the effects of distinct concentrations of genipin and silk fibroin (SF):chitosan (CS) ratios on the formation of SF–CS composite microspheres. We selected microspheres featuring an SF:CS ratio of 1:1, encapsulated various concentrations of bovine serum albumin (BSA), and then compared their encapsulation efficiency and sustained-release rate with those of pure CS microspheres. We determined that the following five groups of microspheres were highly spherical and featured particle sizes ranging from 70 μm to 147 μm: mass ratio of CS:SF =1:0.5, 0.1 g or 0.5 g genipin; CS:SF =1:1, 0.05 g or 1 g genipin; and CS:SF =1:2, 0.5 g genipin. The microspheres prepared using 1:1 CS:SF ratio and 0.05 g genipin in the presence of 10 mg, 20 mg, and 50 mg of BSA exhibited encapsulation efficiencies of 50.16%±4.32%, 56.58%±3.58%, and 42.19%±7.47%, respectively. Fourier-transform infrared spectroscopy (FTIR) results showed that SF and CS were cross-linked and that the α-helices and random coils of SF were converted into β-sheets. BSA did not chemically react with CS or SF. Moreover, thermal gravimetric analysis (TGA) results showed that the melting point of BSA did not change, which confirmed the FTIR results, and X-ray diffraction results showed that BSA was entrapped in microspheres in a noncrystalline form, which further verified the TGA and FTIR data. The sustained-release microspheres prepared in the presence of 10 mg, 20 mg, and 50 mg of BSA burst release 30.79%±3.43%, 34.41%±4.46%, and 41.75%±0.96% of the entrapped BSA on the 1st day and cumulatively released 75.20%±2.52%, 79.16%±4.31%, and 89.04%±4.68% in 21 days, respectively. The pure CS microspheres prepared in the presence of 10 mg of BSA burst release 39.53%±1.76% of BSA on the 1st day and cumulatively released 83.57%±2.33% of the total encapsulated BSA in 21 days. The SF–CS composite microspheres exhibited higher sustained release than did the pure CS microspheres, and thus these composite

  13. Preparation and characterization of genipin-cross-linked silk fibroin/chitosan sustained-release microspheres.

    PubMed

    Zeng, Shuguang; Ye, Manwen; Qiu, Junqi; Fang, Wei; Rong, Mingdeng; Guo, Zehong; Gao, Wenfen

    2015-01-01

    We report the effects of distinct concentrations of genipin and silk fibroin (SF):chitosan (CS) ratios on the formation of SF-CS composite microspheres. We selected microspheres featuring an SF:CS ratio of 1:1, encapsulated various concentrations of bovine serum albumin (BSA), and then compared their encapsulation efficiency and sustained-release rate with those of pure CS microspheres. We determined that the following five groups of microspheres were highly spherical and featured particle sizes ranging from 70 μm to 147 μm: mass ratio of CS:SF =1:0.5, 0.1 g or 0.5 g genipin; CS:SF =1:1, 0.05 g or 1 g genipin; and CS:SF =1:2, 0.5 g genipin. The microspheres prepared using 1:1 CS:SF ratio and 0.05 g genipin in the presence of 10 mg, 20 mg, and 50 mg of BSA exhibited encapsulation efficiencies of 50.16%±4.32%, 56.58%±3.58%, and 42.19%±7.47%, respectively. Fourier-transform infrared spectroscopy (FTIR) results showed that SF and CS were cross-linked and that the α-helices and random coils of SF were converted into β-sheets. BSA did not chemically react with CS or SF. Moreover, thermal gravimetric analysis (TGA) results showed that the melting point of BSA did not change, which confirmed the FTIR results, and X-ray diffraction results showed that BSA was entrapped in microspheres in a noncrystalline form, which further verified the TGA and FTIR data. The sustained-release microspheres prepared in the presence of 10 mg, 20 mg, and 50 mg of BSA burst release 30.79%±3.43%, 34.41%±4.46%, and 41.75%±0.96% of the entrapped BSA on the 1st day and cumulatively released 75.20%±2.52%, 79.16%±4.31%, and 89.04%±4.68% in 21 days, respectively. The pure CS microspheres prepared in the presence of 10 mg of BSA burst release 39.53%±1.76% of BSA on the 1st day and cumulatively released 83.57%±2.33% of the total encapsulated BSA in 21 days. The SF-CS composite microspheres exhibited higher sustained release than did the pure CS microspheres, and thus these composite

  14. A novel approach to preparing magnetic protein microspheres with core-shell structure

    NASA Astrophysics Data System (ADS)

    Jiang, Wei; Sun, Zhendong; Li, Fengsheng; Chen, Kai; Liu, Tianyu; Liu, Jialing; Zhou, Tianle; Guo, Rui

    2011-03-01

    Magnetic protein microspheres with core-shell structure were prepared through a novel approach based on the sonochemical method and the emulsion solvent evaporation method. The microspheres are composed of the oleic acid and undecylenic acid modified Fe 3O 4 cores and coated with globular bovine serum albumin (BSA). Under an optimized condition, up to 57.8 wt% of approximately 10 nm superparamagnetic Fe 3O 4 nanoparticles could be uniformly encapsulated into the BSA microspheres with the diameter of approximately 160 nm and the high saturation magnetization of 38.5 emu/g, besides of the abundant functional groups. The possible formation mechanism of magnetic microspheres was discussed in detail.

  15. [Preparation and clinical application of polyvinyl alcohol/drug-loaded chitosan microsphere composite wound dressing].

    PubMed

    Zhang, Xiuju; Lin, Zhidan; Chen, Wenbin; Song, Ying; Li, Zhizhong

    2011-04-01

    In order to prepare and apply the polyvinyl alcohol/drug-loaded chitosan microspheres composite wound dressing, we first prepared chitosan microspheres by emulsion cross-linking method, and then added chitosan microspheres into the reactants during the acetalization of polyvinyl alcohol and formaldehyde. We further studied the morphology, water absorption, swelling degree, mechanical properties and in vitro release of the sponge with different amount of chitosan microspheres. The results showed that polyvinyl alcohol/drug-loaded chitosan composite sponge has porous structure with connectionism. Increasing the amount of chitosan microspheres would make the apertures smaller, so that the water absorption and the swelling of sponge decreased, but the tensile strength and compressive strength increased. With the increase of the amount of chitosan microspheres, the drug absorption of cefradine and the release rate increase, and the release time become longer. With the results of toxicity grade of 0 to 1, this type of composite sponge is non-toxic and meets the requirement of biocompatibility. The observation of rabbit nasal cavity after surgical operation suggested that polyvinyl acetal sponge modified with the chitosan has antiphlogistic, hemostatic and non-adherent characteristic, and can promote the healing and recovering of the nasalmucosa. After using this composite material, best growing surroundings for patients' granulation tissue were provided. Exposed bone and tendon were covered well with granulation tissue.

  16. Preparation and in vivo evaluation of PCADK/PLGA microspheres for improving stability and efficacy of rhGH.

    PubMed

    Wang, Chenhui; Yu, Changhui; Liu, Jiaxin; Teng, Lesheng; Sun, Fengying; Li, Youxin

    2015-11-30

    The goal of this research is to prepare poly(cyclohexane-1,4 diyl acetone dimethylene ketal) (PCADK)/poly(D,L-lactide-co-glycolide) (PLGA) blend microspheres loaded with recombinant human growth hormone (rhGH). The effect of PCADK degradation products on the structural integrity, secondary and tertiary structure and pharmacodynamics of rhGH was evaluated by native-polyacrylamide gel electrophoresis (Native-PAGE), size-exclusion high performance liquid chromatography (SEC-HPLC), circular dichroism (CD), fluorescence spectroscopy and in hypophysectomized rat models. Compared with PLGA degradation products, rhGH was found to be more stable in the presence of PCADK degradation products. PCADK/PLGA blend microspheres were then prepared and the morphology, encapsulation efficiency, release behavior and rhGH stability were investigated. PCADK/PLGA microspheres had regular shapes and smooth surfaces when the proportion of PCADK was less than 50%. The late-releasable amount of rhGH in PCADK/PLGA microspheres was greater than that in PLGA microspheres. In addition, the PCADK/PLGA microspheres showed larger AUC and improved therapeutic effects on rats than PLGA microspheres. Furthermore, the pH inside the microspheres was detected by CLSM to explain the improved rhGH stability in the PCADK/PLGA microspheres. In conclusion, PCADK/PLGA blend microspheres showed potential to improve rhGH stability and the efficacy of sustained-release of rhGH compared with PLGA microspheres.

  17. Preparation and Certification of K-411 Glass Microspheres.

    PubMed

    Marinenko; Roberson; Small; Thorne; Blackburn; Kauffman; Leigh

    2000-11-01

    The production and characterization of NBS K-411 glass microspheres in the 2-40 µm range for certification as NIST Standard Reference Material(R) 2066 (SRM(R)) are described. Quantitative analysis and heterogeneity testing of the microspheres were done with an electron probe microanalyzer-X-ray energy dispersive spectrometry (EPMA-EDS) automated particle analysis procedure. Results for the trimmed and normalized data produced mean compositions for the elements Mg, Si, Ca, Fe, and O (calculated from stoichiometry) that are in good agreement with the certified values for the K-411 bulk glass (NBS SRM 470 Glasses for Mineral Analysis), but with uncertainties about twice as large as those for the bulk material. Differences from the bulk are attributable to microsphere geometry as well as mass and size effects.

  18. Influence of clay particles on microfluidic-based preparation of hydrogel composite microsphere

    NASA Astrophysics Data System (ADS)

    Hong, Joung Sook

    2016-05-01

    For the successful fabrication of a hydrogel composite microsphere, this study aimed to investigate the influence of clay particles on microsphere formation in a microfluidic device which has flow focusing and a 4.5:1 contraction channel. A poly alginic acid solution (2.0 wt.%) with clay particles was used as the dispersed phase to generate drops in an oil medium, which then merged with drops of a CaCl2 solution for gelation. Drop generations were observed with different flow rates and particles types. When the flow rate increased, drop generation was enhanced and drop size decreased by the build-up of more favorable hydrodynamic flow conditions to detach the droplets. The addition of a small amount of particles insignificantly changed the drop generation behavior even though it reduced interfacial tension and increased the viscosity of the solution. Instead, clays particles significantly affected hydro-gelation depending on the hydrophobicity of particles, which produced further heterogeneity in the shape and size of microsphere.

  19. An oral DNA vaccine against infectious haematopoietic necrosis virus (IHNV) encapsulated in alginate microspheres induces dose-dependent immune responses and significant protection in rainbow trout (Oncorrhynchus mykiss).

    PubMed

    Ballesteros, Natalia A; Alonso, Marta; Saint-Jean, Sylvia Rodríguez; Perez-Prieto, Sara I

    2015-08-01

    Administered by intramuscular injection, a DNA vaccine (pIRF1A-G) containing the promoter regions upstream of the rainbow trout interferon regulatory factor 1A gene (IRF1A) driven the expression of the infectious hematopoietic necrosis virus (IHNV) glycoprotein (G) elicited protective immune responses in rainbow trout (Oncorhynchus mykiss). However, less laborious and cost-effective routes of DNA vaccine delivery are required to vaccinate large numbers of susceptible farmed fish. In this study, the pIRF1A-G vaccine was encapsulated into alginate microspheres and orally administered to rainbow trout. At 1, 3, 5, and 7 d post-vaccination, IHNV G transcripts were detected by quantitative real-time PCR in gills, spleen, kidney and intestinal tissues of vaccinated fish. This result suggested that the encapsulation of pIRF1A-G in alginate microparticles protected the DNA vaccine from degradation in the fish stomach and ensured vaccine early delivery to the hindgut, vaccine passage through the intestinal mucosa and its distribution thought internal and external organs of vaccinated fish. We also observed that the oral route required approximately 20-fold more plasmid DNA than the injection route to induce the expression of significant levels of IHNV G transcripts in kidney and spleen of vaccinated fish. Despite this limitation, increased IFN-1, TLR-7 and IgM gene expression was detected by qRT-PCR in kidney of vaccinated fish when a 10 μg dose of the oral pIRF1A-G vaccine was administered. In contrast, significant Mx-1, Vig-1, Vig-2, TLR-3 and TLR-8 gene expression was only detected when higher doses of pIRF1A-G (50 and 100 μg) were orally administered. The pIRF1A-G vaccine also induced the expression of several markers of the adaptive immune response (CD4, CD8, IgM and IgT) in kidney and spleen of immunized fish in a dose-dependent manner. When vaccinated fish were challenged by immersion with live IHNV, evidence of a dose-response effect of the oral vaccine could also

  20. Preparation and in vitro/in vivo characterization of curcumin microspheres intended to treat colon cancer

    PubMed Central

    Madhavi, M.; Madhavi, K.; Jithan, A. V.

    2012-01-01

    Objective: The objective of the present investigation was to prepare colon targeted curcumin microspheres using Eudragit S100 and evaluate the same for in vitro/in vivo properties. Materials and Methods: A “O/O solvent evaporation” technique was used in the preparation of microspheres. The influence of various process variables including stirring speed, drug:polymer ratio and percentage of emulsifier on the fabrication were investigated and the formulation was optimized. Prepared microspheres were evaluated for in vitro and in vivo properties. Surface morphology, particle size, percentage drug entrapment, percentage yield, drug polymer interaction, in vitro drug release in simulated gastrointestinal transit conditions and stability were the in vitro parameters investigated. Using an optimized formulation, drug release into the systemic circulation and organ distribution were investigated as in vivo parameters. In vivo parameters were estimated in male albino rats. Results: Curcumin microspheres of Eudragit S100 were successfully prepared using o/o solvent evaporation method. Microspheres prepared using 1:2 drug:polymer ratio, with a stirring speed of 1000 rpm, and using 1.0% w/v concentration of emulsifying agent was selected as an optimized formulation. The release studies with optimized formulation demonstrated that aqueous solubility of curcumin was enhanced by 8 times with the formulation. FTIR studies demonstrated no change in drug characteristics upon microsphere fabrication. The enhancement in solubility is thus due to the increase in the surface area of the drug substance and not due to a change of drug to a different physical state. This was further confirmed by scanning electron microsphere pictures. Drug release followed Korsmeyer and Peppas release model. Accelerated stability studies indicated that the drug is stable in the formulation for a period of atleast 14 weeks at room temperature. In vivo studies demonstrated a sustained drug release into

  1. Preparation of cellulose based microspheres by combining spray coagulating with spray drying.

    PubMed

    Wang, Qiao; Fu, Aiping; Li, Hongliang; Liu, Jingquan; Guo, Peizhi; Zhao, Xiu Song; Xia, Lin Hua

    2014-10-13

    Porous microspheres of regenerated cellulose with size in range of 1-2 μm and composite microspheres of chitosan coated cellulose with size of 1-3 μm were obtained through a two-step spray-assisted approach. The spray coagulating process must combine with a spray drying step to guarantee the formation of stable microspheres of cellulose. This approach exhibits the following two main virtues. First, the preparation was performed using aqueous solution of cellulose as precursor in the absence of organic solvent and surfactant; Second, neither crosslinking agent nor separated crosslinking process was required for formation of stable microspheres. Moreover, the spray drying step also provided us with the chance to encapsulate guests into the resultant cellulose microspheres. The potential application of the cellulose microspheres acting as drug delivery vector has been studied in two PBS (phosphate-buffered saline) solution with pH values at 4.0 and 7.4 to mimic the environments of stomach and intestine, respectively.

  2. Controlling the thickness of hollow polymeric microspheres prepared by electrohydrodynamic atomization

    PubMed Central

    Chang, Ming-Wei; Stride, Eleanor; Edirisinghe, Mohan

    2010-01-01

    In this study, the ability to control the shell thickness of hollow polymeric microspheres prepared using electrohydrodynamic processing at ambient temperature was investigated. Polymethylsilsesquioxane (PMSQ) was used as a model material for the microsphere shell encapsulating a core of liquid perfluorohexane (PFH). The microspheres were characterized by Fourier transform infrared spectroscopy and optical and electron microscopy, and the effects of the processing parameters (flow-rate ratio, polymer concentration and applied voltage) on the mean microsphere diameter (D) and shell thickness (t) were determined. It was found that the mean diameters of the hollow microspheres could be controlled in the range from 310 to 1000 nm while the corresponding mean shell thickness varied from 40 to 95 nm. The results indicate that the ratio D : t varied with polymer concentration, with the largest value of approximately 10 achieved with a solution containing 18 wt% of the polymer, while the smallest value (6.6) was obtained at 36 wt%. For polymer concentrations above 63 wt%, hollow microspheres could not be generated, but instead PMSQ fibres encapsulating PFH liquid were obtained. PMID:20519216

  3. Preparation and evaluation of enrofloxacin microspheres and tissue distribution in rats

    PubMed Central

    Yang, Fan; Kang, Jijun; Yang, Fang; Zhao, Zhensheng; Kong, Tao

    2015-01-01

    New enrofloxacin microspheres were formulated, and their physical properties, lung-targeting ability, and tissue distribution in rats were examined. The microspheres had a regular and round shape. The mean diameter was 10.06 µm, and the diameter of 89.93% of all microspheres ranged from 7.0 µm to 30.0 µm. Tissue distribution of the microspheres was evaluated along with a conventional enrofloxacin preparation after a single intravenous injection (7.5 mg of enrofloxacin/kg bw). The results showed that the elimination half-life (t1/2β) of enrofloxacin from lung was prolonged from 7.94 h for the conventional enrofloxacin to 13.28 h for the microspheres. Area under the lung concentration versus time curve from 0 h to ∞ (AUC0-∞) was increased from 11.66 h·µg/g to 508.00 h·µg/g. The peak concentration (Cmax) in lung was increased from 5.95 µg/g to 93.36 µg/g. Three lung-targeting parameters were further assessed and showed that the microspheres had remarkable lung-targeting capabilities. PMID:25643802

  4. [Preparation of cationic dextran microspheres loaded with tetanus toxoid and study on the mechanism of protein loading].

    PubMed

    Zheng, Chun-li; Liu, Xiao-qing; Zhu, Jia-bi; Zhao, Yu-na

    2010-09-01

    The aim of this study is to prepare cationic biodegradable dextran microspheres loaded with tetanus toxoid (TT) and to investigate the mechanism of protein loading. Positively charged microspheres were prepared by polymerization of hydroxylethyl methacrylate derivatized dextran (dex-HEMA) and dimethyl aminoethyl methacrylate (DMAEMA) in an aqueous two-phase system. The loading of the microspheres with TT was based on electrostatic attraction. The net positive surface charge increased with increasing amounts of DMAEMA. Confocal images showed fluorescein isothiocyanate labeled bovine serum albumin (FITC-BSA) could penetrate into cationic dextran microspheres but not natural dextran microspheres. TT loading efficiency by post-loading was higher compared with by pre-loading. Even though TT is incorporated in the hydrogel network based on electrostatic interaction, still a controlled release can be achieved by varying the initial network density of the microspheres.

  5. Alginate-based pellets prepared by extrusion/spheronization: a preliminary study on the effect of additive in granulating liquid.

    PubMed

    Sriamornsak, Pornsak; Nunthanid, Jurairat; Luangtana-anan, Manee; Puttipipatkhachorn, Satit

    2007-08-01

    The aim of this study was to investigate the possibility of producing alginate-based pellets by extrusion/spheronization and also to improve the formation of spherical alginate-based pellets by investigating the effect of additive in granulating liquid on characteristics and drug release from resulting pellets. Two types of sodium alginate (30%) were evaluated in combination with theophylline (20%), microcrystalline cellulose (50%) and different granulation liquids. The pellets were then prepared in a basket extruder, then spheronized and dried. The final products were characterized by morphological examination and drug release study. Different additives in the granulating liquid influenced the ability of the extruded mass to form pellets (the processability) with this technique. However, different sodium alginate types responded to shape modifications to a different extent. Long, dumbbell-shaped pellets were obtained with viscous granulating liquids. However, short, nearly spherical pellets were obtained with watery granulation liquid with calcium chloride that reduced the swelling ability of sodium alginate. Improvements in the pellet characteristics were also dependent on the sodium alginate type employed. Most of pellet formulations released about 75-85% drug within 60min and showed a good fit into both Higuchi and Korsmeyer-Peppas equations. Higher amount of 3% calcium chloride, as a granulating liquid, in the formulation showed higher mean dissolution time resulting from the cross-linking properties of calcium ions to the negative charges of alginate molecules.

  6. Preparation of Syndiotactic Poly(vinyl alcohol)/Poly(vinyl pivalate/vinyl acetate) Microspheres with Radiopacity Using Suspension Copolymerization and Saponification

    NASA Astrophysics Data System (ADS)

    Seok Lyoo, Won; Wook Cha, Jin; Young Kwak, Kun; Jae Lee, Young; Yong Jeon, Han; Sik Chung, Yong; Kyun Noh, Seok

    2010-06-01

    To prepare Poly(vinyl pivalate/vinyl acetate) [P(VPi/VAc)] microspheres with radiopacity, the suspension copolymerization approach in the presence of aqueous radiopaque nanoparticles was used. After, The P(VPi/VAc) microspheres with radiopacity were saponified in heterogeneous system, and then P(VPi/VAc) microspheres without aggregates were converted to s-PVA/P(VPi/VAc) microspheres of skin/core structure through the heterogeneous surface saponification. Radiopacity of microspheres was confirmed with Computed tomography (CT).

  7. Preparation and characterization of electrospun alginate/PLA nanofibers as tissue engineering material by emulsion eletrospinning.

    PubMed

    Xu, Weihong; Shen, Renzhe; Yan, Yurong; Gao, Jie

    2017-01-01

    Scaffolds made by biomaterials offer favorite environment for cell grow and show a wide potential application in tissue engineering. Novel biocompatibility materials polylatic acid (PLA) nanofiber membranes with favorable biocompatibility and good mechanical strength could serve as an innovative tissue engineering scaffold. Sodium alginate (SA) could be used in biomedical areas because of its anti-bacterial property, hydrophilicity and biocompatibility. In this article, we chose PLA as continuous phase and SA as dispersion phase to prepare a W/O emulsion and then electrospun it to get a SA/PLA composite nanofiber membranes. The CLSM images illustrated that the existence of SA was located on the surface of composite fibers and the FTIR results confirmed the result. A calcium ion replacement step was used as an after-treatment for SA/PLA nanofiber membranes in order to anchor the alginic ion in a form of gelated calcium alginate (CA). The single fiber tensile test shows a good mechanical property of CA/PLA nanofiber membranes, and the nanofiber membranes are beneficial for cell proliferation and differentiation owing to MTT array as well as Alizarin red S (ARS) staining test.

  8. Streptomycin-loaded PLGA-alginate nanoparticles: preparation, characterization, and assessment

    NASA Astrophysics Data System (ADS)

    Asadi, Asadollah

    2013-04-01

    The aim of this study was to formulate and characterize streptomycin-loaded PLGA-alginate nanoparticles for their potential therapeutic use in Salmonella subsp. enterica ATCC 14028 infections. The streptomycin nanoparticle was prepared by solvent diffusion method, and the other properties such as size, zeta potential, loading efficacy, release kinetics, and antimicrobial strength were evaluated. The survey shows that nanoparticles may serve as a carrier of streptomycin and may provide localized antibacterial activity in the treatment of Salmonellosis. Electron microscopy showed spherical particles with indentations. The average size of the nanoparticles was 90 nm. At pH 7.2, the release kinetics of streptomycin from the nanoparticles was successfully illustrated as an initial burst defined by a first order equation that after this stage, it has a drastic tendency to obtain steady state. Nevertheless, nanoparticles showed loading efficacy nearly about 70-75 %. In addition, the tendency of concentration of streptomycin released from nanoparticles to reach antibacterial activity was similar to that of free streptomycin against PLGA-alginate, but it had threefold more antimicrobial strength in comparison with free streptomycin. This work shows the potential use of streptomycin-loaded PLGA-alginate nanoparticles and its capability.

  9. Streptomycin-loaded PLGA-alginate nanoparticles: preparation, characterization, and assessment

    NASA Astrophysics Data System (ADS)

    Asadi, Asadollah

    2014-04-01

    The aim of this study was to formulate and characterize streptomycin-loaded PLGA-alginate nanoparticles for their potential therapeutic use in Salmonella subsp. enterica ATCC 14028 infections. The streptomycin nanoparticle was prepared by solvent diffusion method, and the other properties such as size, zeta potential, loading efficacy, release kinetics, and antimicrobial strength were evaluated. The survey shows that nanoparticles may serve as a carrier of streptomycin and may provide localized antibacterial activity in the treatment of Salmonellosis. Electron microscopy showed spherical particles with indentations. The average size of the nanoparticles was 90 nm. At pH 7.2, the release kinetics of streptomycin from the nanoparticles was successfully illustrated as an initial burst defined by a first order equation that after this stage, it has a drastic tendency to obtain steady state. Nevertheless, nanoparticles showed loading efficacy nearly about 70-75 %. In addition, the tendency of concentration of streptomycin released from nanoparticles to reach antibacterial activity was similar to that of free streptomycin against PLGA-alginate, but it had threefold more antimicrobial strength in comparison with free streptomycin. This work shows the potential use of streptomycin-loaded PLGA-alginate nanoparticles and its capability.

  10. In vitro and in vivo performance of dexamethasone loaded PLGA microspheres prepared using polymer blends.

    PubMed

    Gu, Bing; Wang, Yan; Burgess, Diane J

    2015-12-30

    The foreign body reaction is the major cause of the dysfunction and relatively short lifetime associated with implanted glucose biosensors. An effective strategy to maintain sensor functionality is to apply biocompatible coatings that elute drug to counter the negative tissue reactions. This has been achieved using dexamethasone releasing poly(lactic-co-glycolic acid) (PLGA) microspheres embedded in a polyvinyl alcohol (PVA) hydrogel coating. Accordingly, the biosensor lifetime relies on the duration and dose of drug release from the coating. To achieve long-term drug release mixed populations of microspheres have been used. In the current study, microspheres were prepared by blending low (25KDa) and high (113KDa) molecular weight PLGA at different mass ratios to overcome problems associated with mixing multiple populations of microspheres. "Real-time" in vitro studies demonstrated dexamethasone release for approximately 5 months. An accelerated method with discriminatory ability was developed to shorten drug release to less than 2 weeks. An in vivo pharmacodynamics study demonstrated efficacy against the foreign body reaction for 4.5 months. Such composite coatings composed of PLGA microspheres prepared using polymer blends could potentially be used to ensure long-term performance of glucose sensors.

  11. Preparation of (U,Pu)O 2 pellets through sol-gel microsphere pelletization technique

    NASA Astrophysics Data System (ADS)

    Kumar, N.; Pai, Rajesh V.; Joshi, J. K.; Mukerjee, S. K.; Vaidya, V. N.; Venugopal, V.

    2006-12-01

    Mixed uranium-plutonium oxide microspheres were prepared by internal gelation process using feed solution of optimized composition. In the feed, total metal concentration was maintained at 1.5 M and hexamethylenetetramine (HMTA)-urea to metal mole ratio ( R) was kept at 1.0. The gel particles obtained from each batch were dried and heated at 250 °C in air and then calcined in O 2 at 800 °C followed by reduction in 8%H 2/92%N 2 at 600 °C for 1 h to obtain soft (U,Pu)O 2 microspheres containing 4 mol% Pu. The soft (U,Pu)O 2 microspheres were directly taken for the preparation of pellets. The microspheres were characterized with respect to surface area, tap density, crush strength and O/M ratio. X-ray diffraction analysis of the mixed oxide microspheres was carried out to identify the phases. The mixed oxide pellets were characterized for their density and micro-homogeneity. The sintering behaviour was studied by dilatometric investigations. The green pellets were sintered in 8%H 2/92%N 2 at 1600 °C for 2 h. The density of the sintered pellet was found to be 10.40 ± 0.05 g/cm 3 with grains in the size range of 3-6 μm with an excellent micro-homogeneity.

  12. Theophylline-loaded compritol microspheres prepared by ultrasound-assisted atomization.

    PubMed

    Fini, Adamo; Cavallari, Cristina; Ospitali, Francesca; Gonzalez-Rodriguez, M Luisa

    2011-02-01

    Nine solid dispersions were prepared by the melting method in the form of particles containing theophylline at 10%, 20%, and 30% (w/w) in three Compritols (Compritol 888 ATO, HD5 ATO, E ATO) to compare their efficiency in controlling theophylline release. After solidification the mass was ground and granules were evaluated by thermal [differential scanning calorimetry, hot stage microscopy (HSM)] and spectroscopic [Fourier transform infrared (FTIR), Raman, X-ray powder diffraction (XRD)] analysis and the solubility parameters. Another nine samples of the same composition were obtained as microspheres by ultrasound-assisted (US) atomization. XRD confirmed the presence of crystalline theophylline inside the solid dispersions. FTIR and Raman microspectroscopy revealed that crystals of the drug were present on the granule surface. On the contrary, the surface of the final microspheres did not present free drug crystals. The granules do not work so efficiently as microspheres in controlling the release of theophylline: 888 ATO ≈ HD5 ATO > E ATO represents the order of the ability of the Compritols to control the theophylline release from microspheres. HSM revealed that, on aging, the dissolved drug crystallizes, considerably modifying the granule formulation and that US vibration, speeding up the crystallization of the drug during the preparation of microspheres, greatly reduces the changes associated with aging.

  13. Preparation of polystyrene microspheres for laser velocimetry in wind tunnels

    NASA Technical Reports Server (NTRS)

    Nichols, Cecil E., Jr.

    1987-01-01

    Laser Velocimetry (L/V) had made great strides in replacing intrusive devices for wind tunnel flow measurements. The weakness of the L/V has not been the L/V itself, but proper size seeding particles having known drag characteristics. For many Langley Wind Tunnel applications commercial polystyrene latex microspheres suspended in ethanol, injected through a fluid nozzle provides excellent seeding but was not used due to the high cost. This paper provides the instructions, procedures, and formulations for producing polystyrene latex monodisperse microspheres of 0.6, 1.0, 1.7, 2.0, and 2.7 micron diameters. These are presently being used at Langley Research Center as L/V seeding particles.

  14. PREPARATION AND CHARACTERIZATION OF POROUS WALLED HOLLOW GLASS MICROSPHERES

    SciTech Connect

    Raszewski, F; Erich Hansen, E; Ray Schumacher, R; David Peeler, D

    2008-04-21

    Porous-walled hollow glass microspheres (PWHGMs) of a modified alkali borosilicate composition have been successfully fabricated by combining the technology of producing hollow glass microspheres (HGMs) with the knowledge associated with porous glasses. HGMs are first formed by a powder glass--flame process, which are then transformed to PWHGMs by heat treatment and subsequent treatment in acid. Pore diameter and pore volume are most influenced by heat treatment temperature. Pore diameter is increased by a factor of 10 when samples are heat treated prior to acid leaching; 100 {angstrom} in non-heat treated samples to 1000 {angstrom} in samples heat treated at 600 C for 8 hours. As heat treatment time is increased from 8 hours to 24 hours there is a slight shift increase in pore diameter and little or no change in pore volume.

  15. Effect of different dispersing agents on the characteristics of Eudragit microspheres prepared by a solvent evaporation method.

    PubMed

    Horoz, B B; Kiliçarslan, M; Yüksel, N; Baykara, T

    2004-03-01

    Eudragit RS microspheres containing verapamil HCl for oral use were prepared using three different dispersing agents: aluminium tristearate, magnesium stearate and sucrose stearate, by a solvent evaporation method. The effects of the type and concentration of the dispersing agents and the inner phase polymer concentration on the size and T63.2%, (the time at which 63.2% of the drug is released) of microspheres were determined by multiple linear regression analysis. The morphology of microspheres was characterized by scanning electron microscopy. The surface of microspheres prepared with sucrose stearate was smoother and non-porous and the drug release from these microspheres was the fastest. When aluminium tristearate or magnesium stearate were used as dispersing agents, the particle size of microspheres became smaller. Increasing amounts of these two dispersing agents led to the accumulation of their free particles onto the surfaces of the microspheres. The drug release from the microspheres was slower than that of the microspheres from sucrose stearate depending on their hydrophobic structures. According to the results of the multiple linear regression analysis among the dispersing agents used, aluminium tristearate showed the best correlation between the examined input (dispersing agent and polymer concentrations) and output (T63.2%. and particle size) variables.

  16. Preparation and in vitro evaluation of xanthan gum facilitated superabsorbent polymeric microspheres.

    PubMed

    Bhattacharya, Shiv Sankar; Mazahir, Farhan; Banerjee, Subham; Verma, Anurag; Ghosh, Amitava

    2013-10-15

    Interpenetrating polymer network (IPN) hydrogel microspheres of xanthan gum (XG) based superabsorbent polymer (SAP) and poly(vinyl alcohol) (PVA) were prepared by water-in-oil (w/o) emulsion crosslinking method for sustained release of ciprofloxacin hydrochloride (CIPRO). The microspheres were prepared with various ratios of hydrolyzed SAP to PVA and extent of crosslinking density. The prepared microspheres with loose and rigid surfaces were evidenced by scanning electron microscope (SEM). Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) analysis confirmed the IPN formation. Differential scanning calorimetry (DSC) study was performed to understand the dispersion nature of drug after encapsulation. The in vitro drug release study was extensively evaluated depending on the process variables in both acidic and alkaline media. All the formulations exhibited satisfactory physicochemical and in vitro release characteristics. Release data indicated a non-Fickian trend of drug release from the formulations. Based on the results, this study suggest that CIPRO loaded IPN microspheres were suitable for sustained release application.

  17. Preparation, Characterization and in vivo Evaluation of Parenteral Sustained Release Microsphere Formulation of Zopiclone

    PubMed Central

    Swapna, N; Jithan, AV

    2010-01-01

    The aim of this study was to prepare zopiclone-loaded polycaprolactone microspheres by emulsion solvent evaporation technique with different drug-to-carrier ratios {MP 1 (1:1), MP 2 (1:2), MP 3 (1:3), and MP 4 (1:4)}, characterize and evaluate the in vivo performance. The microspheres were characterized for particle size, surface morphology, drug excipient compatibility, percentage yield, drug entrapment, and in vitro release kinetics. Pharmacokinetics and pharmacodynamics were evaluated after parenteral administration so as to determine the sustained action of the drug after one-time administration of the formulation in a rat model. Of four formulations prepared, MP 2, i.e., 1:2 (drug–polymer) ratio was selected as the optimized formulation based on particle size, particle shape, and the release behavior. The size of microspheres was found to be ranging from 5.4 to 12.1 µm. The shape of microspheres was found to be spherical by SEM. Among the four formulations, MP 2 (1:2) showed maximum percentage yield of 75% ± 2.68%. There was no interaction between drug and polymer by FT-IR study. In the in vitro release study, formulation MP 2 (1:2) showed 86.5% drug release and was found to be sustained for 10 days. The microsphere formulations were able to sustain the release of drug both in vitro and in vivo. Pharmacodynamic study (Maze apparatus) indicated that the anxiolytic activity shown by zopiclone microspheres was significant when compared to the zopiclone solution given daily. PMID:21042475

  18. Micromeritics and release behaviours of cellulose acetate butyrate microspheres containing theophylline prepared by emulsion solvent evaporation and emulsion non-solvent addition method.

    PubMed

    Jelvehgari, Mitra; Atapour, Fatemeh; Nokhodchi, Ali

    2009-07-01

    The present research work compares the effect of microsphere preparation technique on micromeritics and release behaviors of theophylline microspheres. Microspheres were prepared by oil-in oil (O(1)/O(2)) emulsion solvent evaporation method (ESE) using different ratios of anhydrous theophylline to cellulose acetate butyrate (CAB). Cyclohexane was used as non-solvent to modify the ESE technique (MESE method) and the effect of non-solvent volume on properties of microspheres was investigated. The obtained microspheres were analyzed in terms of drug content, particle size and encapsulation efficiency. The morphology of microsphere was studied using scanning electron microscope. The solid state of microspheres, theophylline and CAB were investigated using X-ray, FT-IR and DSC. The drug content of microspheres prepared by MESE method was significantly lower (15.54% +/- 0.46) than microspheres prepared by ESE method (41.08 +/- 0.40%). The results showed that as the amount of cyclohexane was increased from 2 mL to 6 mL the drug content of microspheres was increased from 15.54% to 28.71%. Higher encapsulation efficiencies were obtained for microspheres prepared by ESE method (95.87%) in comparison with MESE method (64.71%). Mean particle size of microsphere prepared by ESE method was not remarkably affected by drug to polymer ratio, whereas in MSES method when the volume of cyclohexane was increased the mean particle size of microsphere was significantly decreased. The ratio of drug to polymer significantly changed the rate of drug release from microspheres and the highest drug release was obtained for the microsphere with high drug to polymer ratio. The amount of cyclohexane did not significantly change the drug release. Although, x-ray showed a small change in crystallinity of theophylline in microspheres, DSC results proved that theophylline in microspheres is in amorphous state. No major chemical interaction between the drug and polymer was reported during the

  19. Preparation and characterization of polycaprolactone microspheres by electrospraying

    PubMed Central

    Zhou, Feng-Lei; Hubbard Cristinacce, Penny L.; Eichhorn, Stephen J.; Parker, Geoff J. M.

    2016-01-01

    ABSTRACT The ability to reproducibly produce and effectively collect electrosprayed polymeric microspheres with controlled morphology and size in bulk form is challenging. In this study, microparticles were produced by electrospraying polycaprolactone (PCL) of various molecular weights and solution concentrations in chloroform, and by collecting materials on different substrates. The resultant PCL microparticles were characterized by optical and electron microscopy to investigate the effect of molecular weight, solution concentration, applied voltage, working distance, and flow rate on their morphology and size. The work demonstrates the key role of a moderate molecular weight and/or solution concentration in the formation of spherical PCL particles via an electrospraying process. Increasing the applied voltage was found to produce smaller and more uniform PCL microparticles. There was a relatively low increase in the particle average size with an increase in the working distance and flow rate. Four types of substrates were adopted to collect electrosprayed PCL particles: a glass slide, aluminium foil, liquid bath, and copper wire. Unlike 2D bulk structures collected on the other substrates, a 3D tubular structure of microspheres was formed on the copper wire which could find application in the construction of 3D tumor mimics. PMID:27928195

  20. Preparation and in-vitro evaluation of sustained-release metoclopramide hydrochloride microspheres.

    PubMed

    Khidr, S H; Niazy, E M; el-Sayed, Y M

    1995-01-01

    Sustained-release metoclopramide microspheres were successfully prepared using cellulose propionate polymer at 1:2 drug to polymer ratio employing solvent evaporation technique and using acetone as the polymer solvent. The prepared microspheres at three stirring speeds were characterized with regard to their drug content, particle size distribution, surface topography using SEM and their release profiles at two different pHs at 37 degrees C. The surface of all samples was smooth with very few irregular elevations or depressions. The average particle size decreases as the rotational speed increases and was found to be 1320, 774 and 345 microns at 600, 900 and 1200 rpm, respectively. The average % drug entrapped was found to be 90.5, 100.1 and 60.0% at 600, 900 and 1200 rpm, respectively. Small differences in the release rate were observed due to different rotation speeds with an apparent lower dissolution for batches produced at 1200 rpm probably due to the properties of the coat. The effect of storage under accelerated conditions for 10 weeks on the release characteristics of these microspheres was also studied. The release properties of the microspheres did not change after storing them at 40 degrees C/80% relative humidity for 10 weeks.

  1. Preparation of hierarchical TiO2 microspheres for enhancing photocurrent of dye sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Jia, QiaoYing; Que, WenXiu; Qiu, XinKu; Zhong, Peng; Chen, Jin

    2012-07-01

    Hierarchically structured TiO2 microspheres were prepared at a low temperature by combining a sol-gel process with a solvothermal route and characterized by scanning electron microscopy, transmission electron microscopy and X-ray diffraction analysis. Results indicate that the phase structure of the as-prepared TiO2 products undergoes a transformation, which changes from amorphous microspheres with a smooth surface in the sol-gel process to hierarchical anatase ones consisting of nanocrystallines after the solvothermal treatment. The hierarchical anatase TiO2 microsphere shows large surface areas and good light scattering effects as the photoelectrodes for dye sensitized solar cells (DSSCs). DSSCs based on TiO2 microspheres exhibit an improvement power conversion efficiency of 6.58% and a high short current density of 13.83 mA/cm2 as compared to the commercial P25 based DSSCs with a power conversion efficiency of 4.94% and a high short current density of 10.28 mA/cm2.

  2. Preparation and in vitro characterization of mucoadhesive hydroxypropyl guar microspheres containing amlodipine besylate for nasal administration.

    PubMed

    Swamy, N G N; Abbas, Z

    2011-11-01

    Amlodipine besylate microspheres for intranasal administration were prepared with an aim to avoid first-pass metabolism, to achieve controlled blood level profiles and to improve therapeutic efficacy. Hydroxypropyl Guar, a biodegradable polymer, was used in the preparation of microspheres by employing water in oil emulsification solvent evaporation technique. The formulation variables were drug concentration, emulsifier concentration, temperature, agitation speed and polymer concentration. All the formulations were evaluated for particle size, particle shape and surface morphology by scanning electron microscopy, percentage yield, drug entrapment efficiency, in vitro mucoadhesion test, degree of swelling and in vitro drug diffusion through sheep nasal mucosa. The microspheres obtained were free flowing, spherical and the particles ranged in size from 13.4±2.38 μm to 43.4±1.92 μm very much suitable for nasal delivery. Increasing polymer concentration resulted in increased drug entrapment efficiency and increased particle size. Amlodipine besylate was entrapped into the microspheres with an efficiency of 67.2±1.18 % to 81.8±0.64 %. The prepared microspheres showed good mucoadhesion properties, swellability and sustained the release of the drug over a period of 8 h. The data obtained were analysed by fitment into various kinetic models; it was observed that the drug release was matrix diffusion controlled and the release mechanism was found to be non-Fickian. Stability studies were carried out on selected formulations at 5±3°, 25±2°/60±5% RH and 40±2°/75±5% RH for 90 days. The drug content was observed to be within permissible limits and there were no significant deviations in the in vitro mucoadhesion and in vitro drug diffusion characteristics.

  3. Preparation and In Vitro Characterization of Mucoadhesive Hydroxypropyl Guar Microspheres Containing Amlodipine Besylate for Nasal Administration

    PubMed Central

    Swamy, N. G. N.; Abbas, Z.

    2011-01-01

    Amlodipine besylate microspheres for intranasal administration were prepared with an aim to avoid first-pass metabolism, to achieve controlled blood level profiles and to improve therapeutic efficacy. Hydroxypropyl Guar, a biodegradable polymer, was used in the preparation of microspheres by employing water in oil emulsification solvent evaporation technique. The formulation variables were drug concentration, emulsifier concentration, temperature, agitation speed and polymer concentration. All the formulations were evaluated for particle size, particle shape and surface morphology by scanning electron microscopy, percentage yield, drug entrapment efficiency, in vitro mucoadhesion test, degree of swelling and in vitro drug diffusion through sheep nasal mucosa. The microspheres obtained were free flowing, spherical and the particles ranged in size from 13.4±2.38 μm to 43.4±1.92 μm very much suitable for nasal delivery. Increasing polymer concentration resulted in increased drug entrapment efficiency and increased particle size. Amlodipine besylate was entrapped into the microspheres with an efficiency of 67.2±1.18 % to 81.8±0.64 %. The prepared microspheres showed good mucoadhesion properties, swellability and sustained the release of the drug over a period of 8 h. The data obtained were analysed by fitment into various kinetic models; it was observed that the drug release was matrix diffusion controlled and the release mechanism was found to be non-Fickian. Stability studies were carried out on selected formulations at 5±3°, 25±2°/60±5% RH and 40±2°/75±5% RH for 90 days. The drug content was observed to be within permissible limits and there were no significant deviations in the in vitro mucoadhesion and in vitro drug diffusion characteristics. PMID:23112393

  4. Studies on the preparation, characterization and pharmacological evaluation of tolterodine PLGA microspheres.

    PubMed

    Sun, Fengying; Sui, Cheng; Teng, Lesheng; Liu, Ximing; Teng, Lirong; Meng, Qingfan; Li, Youxin

    2010-09-15

    In this study, poly(d,l-lactide-co-glycolide) (PLGA) microspheres of tolterodine depot formulation were prepared using oil in water (o/w) method to investigate their potential pharmacokinetic and pharmacodynamic advantages over tolterodine l-tartrate tablets. Morphological studies of the microspheres showed a spherical shape and smooth surface with mean size of 50.69-83.01 microm, and the encapsulation efficiency was improved from 62.55 to 79.10% when the polymer concentration increased from 180 to 230 mg/ml. The addition of stearic or palmitic acids could significantly raise the drug entrapment efficiency but only slightly affected the in vitro release. A low initial burst followed by a proximately constant release of tolterodine was noticed in the in vitro release profiles. The in vivo study was carried out by intramuscular (i.m.) administration of tolterodine-loaded microspheres on beagle dogs, and a sustained release of drug from the PLGA microspheres was achieved until the 18th day with a low initial burst. Since the absence of hepatic first pass metabolism, only a single active compound-tolterodine was detected in the plasma. This avoided the coexistence of two active compounds in plasma in the case of oral administration of tolterodine, which may lead to a difficulty in dose control due to the different metabolic capacity of patients. In the pharmacodynamic study, the influence of tolterodine PLGA microspheres on the inhibition of carbachol-induced rat urinary bladder contraction was more significant than that of tolterodine l-tartrate tablets. There were invisible changes in rat bladder slices between tolterodine-loaded PLGA microspheres group and tolterodine l-tartrate tablets group. These results indicate that the continuous inhibition of muscarinic receptor may offer an alternative therapy of urge incontinence.

  5. Preparation and detection of calcium alginate/bone powder hybrid microbeads for in vitro culture of ADSCs.

    PubMed

    Song, Kedong; Yan, Xinyu; Li, Shixiao; Zhang, Yu; Wang, Hong; Wang, Ling; Lim, Mayasari; Liu, Tianqing

    2015-01-01

    Calcium alginate microbeads have been widely used in tissue engineering application, due to their excellent biocompatibility, biodegradability, enhanced mechanical strength and toughness. Bone powder containing abundant hydroxylapatite, type I collagen and growth factors such as BMP2 and BMP4, possesses good osteoinductive activity. Herein, a hybrid calcium alginate/bone powder microbead was therefore prepared. Afterwards, different seeding density of adipose-derived stem cells (ADSCs) in these hybrid microbeads was discussed systematically for further in vitro expansion. Optimised microbeads suitable for in vitro expansion and differentiation of ADSCs were prepared using the droplet method under overall considering suitable concentrations of calcium alginate and calcium chloride as well as the density of bone powder through an orthogonal experiment. The results showed that the concentration of sodium alginate had the most influence on inside mass transfer and mechanical strength of the hybrid microbeads, secondly the calcium chloride, then the density of bone powder. The hybrid microbeads could be optimally performed while the concentrations of sodium alginate and calcium chloride were 2.5% and 4.5%, as well as 5.0 mg/mL bone powder, respectively. Live/Dead assay showed that the expanded ADSCs differentiated well with an initial embedding density of 5 × 10(6) cells/mL.

  6. Preparation of superparamagnetic sodium alginate nanoparticles for covalent immobilization of Candida rugosa lipase

    NASA Astrophysics Data System (ADS)

    Liu, Xiao; Chen, Xia; Li, Yanfeng; Cui, Yanjun; Zhu, Hao; Zhu, Weiwei

    2012-03-01

    Superparamagnetic sodium alginate nanoparticles with diameter around 25-30 nm were prepared with a water-in-oil emulsion method. The resulted magnetic SA nanoparticle was activated with glutaraldehyde and epichlorohydrin to form nanoscale support. Candida rugosa lipase (CRL), hereby chosen as a model enzyme, was covalently immobilized on the resulted magnetic support. The structure and magnetic behavior of the magnetic nanoparticles were confirmed by transmission electron microscopy, Fourier transform infrared spectroscopy, and vibrating sample magnetometer. Based on the structural character of enzyme (containing functional residues that are ideal reaction sites for the immobilization of enzyme repeatedly), the regeneration of support was investigated by reactivating the deactivated immobilized lipase with glutaraldehyde. And the results indicated that these regenerated supports remained to be efficient for lipase immobilization. Finally, all of the immobilized CRL prepared by different generations of supports displayed excellent reusability and applicability.

  7. Tabletted microspheres containing Cynara scolymus (var. Spinoso sardo) extract for the preparation of controlled release nutraceutical matrices.

    PubMed

    Gavini, E; Alamanni, M C; Cossu, M; Giunchedi, P

    2005-08-01

    Controlled release dosage forms based on tabletted microspheres containing fresh artichoke Cynara scolymus extract were performed for the oral administration of a nutritional supplement. Microspheres were prepared using a spray-drying technique; lactose or hypromellose have been chosen as excipients. Microspheres were characterized in terms of encapsulated extract content, size and morphology. Qualitative and quantitative composition of the extract before and after the spray process was determined. Compressed matrices (tablets) were prepared by direct compression of the spray-dried microspheres. In vitro release tests of microparticles and tablets prepared were carried out in both acidic and neutral media. Spray-drying is a good method to prepare microspheres containing the artichoke extract. The microspheres encapsulate an amount of extract close to the theoretical value. Particle size analyses indicate that the microparticles have dvs of approximately 6-7 microm. Electronic microscopy observations reveal that particles based on lactose have spherical shape and particles containing hypromellose are almost collapsed. The hydroalcoholic extract is stable to the microsphere production process: its polyphenolic composition (qualitative and quantitative) did not change after spraying. In vitro release studies show that microparticles characterized by a quick polyphenolic release both in acidic and neutral media due to the high water solubility of the carrier lactose. On the contrary, microspheres based hypromellose release only 20% of the loaded extract at pH 1.2 in 2 h and the total amount of polyphenols is released only after about further 6 h at pH 6.8. Matrices prepared tabletting lactose microspheres and hypromellose microparticles in the weight ratio 1:1 show a slow release rate, that lasts approximately 24 h. This one-a-day sustained release formulation containing Cynara scolymus extract could be proposed as a nutraceutical controlled release dosage form for

  8. Polylactide-based microspheres prepared using solid-state copolymerized chitosan and d,l-lactide.

    PubMed

    Demina, T S; Akopova, T A; Vladimirov, L V; Zelenetskii, A N; Markvicheva, E A; Grandfils, Ch

    2016-02-01

    Amphiphilic chitosan-g-poly(d,l-lactide) copolymers have been manufactured via solid-state mechanochemical copolymerization and tailored to design polyester-based microspheres for tissue engineering. A single-step solid-state reactive blending (SSRB) using low-temperature co-extrusion has been used to prepare these copolymers. These materials have been valorized to stabilize microspheres processed by an oil/water emulsion evaporation technique. Introduction of the copolymers either in water or in the oil phase of the emulsion allowed to replace a non-degradable emulsifier typically used for microparticle preparation. To enhance cell adhesion, these copolymers were also tailored to bring amino-saccharide positively charged segments to the microbead surface. Size distribution, surface morphology, and total microparticle yield have been studied and optimized as a function of the copolymer composition.

  9. Preparation of Giant Vesicles Encapsulating Microspheres by Centrifugation of a Water-in-oil Emulsion.

    PubMed

    Natsume, Yuno; Wen, Hsin-I; Zhu, Tong; Itoh, Kazumi; Sheng, Li; Kurihara, Kensuke

    2017-01-24

    The constructive biology and the synthetic biology approach to creating artificial life involve the bottom-up assembly of biological or nonbiological materials. Such approaches have received considerable attention in research on the boundary between living and nonliving matter and have been used to construct artificial cells over the past two decades. In particular, Giant Vesicles (GVs) have often been used as artificial cell membranes. In this paper, we describe the preparation of GVs encapsulating highly packed microspheres as a model of cells containing highly condensed biomolecules. The GVs were prepared by means of a simple water-in-oil emulsion centrifugation method. Specifically, a homogenizer was used to emulsify an aqueous solution containing the materials to be encapsulated and an oil containing dissolved phospholipids, and the resulting emulsion was layered carefully on the surface of another aqueous solution. The layered system was then centrifuged to generate the GVs. This powerful method was used to encapsulate materials ranging from small molecules to microspheres.

  10. Preparation of thermo-responsive superhydrophobic TiO2/poly(N-isopropylacrylamide) microspheres

    NASA Astrophysics Data System (ADS)

    Chen, Hao; Pan, Shuaijun; Xiong, Yuzi; Peng, Chang; Pang, Xiangzhong; Li, Ling; Xiong, Yuanqin; Xu, Weijian

    2012-10-01

    Here we reported a facile method that combined sol-gel and surface-initiated atom transfer radical polymerization (ATRP) to prepare thermo-responsive superhydrophobic TiO2/poly(N-isopropylacrylamide) microspheres with core-shell structure. The surface coated with microspheres show hydrophilic properties (CA = 90.5 ± 2.3°) at 27 °C, it changes to superhydrophobicity (CA = 150.2 ± 2.3°) while the temperature rises up to 42 °C. This performance is attributed to lower critical solution temperature (LCST) phenomenon of Poly (N-isopropylacrylamide). Five cycle measurements of water droplet reversible switch between hydrophilicity and superhydrophobicity were demonstrated temperature-responsive surface property. The changes were rapid and significant. The as-prepared particles have been characterized by scanning electron microscopy, transmission electron microscopy, thermal gravimetric analysis, FT-IR analysis, and dynamic light scattering.

  11. Preparation and characterization of isoniazid and lamivudine co-loaded polymeric microspheres.

    PubMed

    Pandey, Gitu; Yadav, Sarita Kumari; Mishra, Brahmeshwar

    2016-12-01

    Context The rate of co-infection of HIV/Tuberculosis is increasing alarmingly. This calls for a drug delivery approach targeting both diseases. Objective The study aims to investigate co-loading of isoniazid, an antitubercular drug and lamivudine an antiretroviral drug, into polymeric microspheres for simultaneous treatment of both diseases. Materials and methods Microspheres were prepared by o/o emulsion solvent evaporation method by employing ethylcellulose and eudragit RS 100 as polymers. The prepared formulation was suitably characterized for FTIR, DSC, percent yield, loose surface crystals, entrapment efficiency, and in vitro studies. The surface morphology of microspheres was observed using digital microscope and scanning electron microscope. Cell viability study was done on Caco-2 cells. Results and discussion FTIR and DSC studies demonstrated compatibility and stability of excipients. Microscopy studies revealed that particles were spherical in shape and distributed over a range of 120-270 μm. Percent yield, LSC and %EE have shown promising results. In vitro release showed biphasic release pattern with sustained release up to 12 h. Mechanism of drug release followed Higuchi Kinetics and non-fickian release behaviour. The formulation containing drug/polymer ratio 1:2 and EU/EC of 1:1 showed optimum response in context to achievement of controlled release. The cell viability studies showed that the prepared system had no toxic effect on intestinal epithelial Caco-2 cells. Conclusion Polymeric microspheres were prepared and suitably characterized for simultaneous delivery of two drugs. This matrix system could be used for better therapeutic outcome in this deadly co-infection.

  12. Preparation of microfibrillated cellulose/chitosan-benzalkonium chloride biocomposite for enhancing antibacterium and strength of sodium alginate films.

    PubMed

    Liu, Kai; Lin, Xinxing; Chen, Lihui; Huang, Liulian; Cao, Shilin; Wang, Huangwei

    2013-07-03

    The nonantibacterial and low strength properties of sodium alginate films negatively impact their application for food packaging. In order to improve these properties, a novel chitosan-benzalkonium chloride (C-BC) complex was prepared by ionic gelation using tripolyphosphate (TPP) as a coagulant, and a biocomposite obtained through the adsorption of C-BC complex on microfibrillated cellulose, MFC/C-BC, was then incorporated into a sodium alginate film. The TEM image showed that the C-BC nanoparticles were spherical in shape with a diameter of about 30 nm, and the adsorption equilibrium time of these nanoparticles on the surface of MFC was estimated to be 6 min under the driving forces of hydrogen bonds and electrostatic interactions. According to the disc diffusion method, the MFC/C-BC biocomposite-incorporated sodium alginate film exhibited remarkable antibacterial activity against Staphylococcus aureus and certain antibacterial activity against Escherichia coli . The strength tests indicated that the tensile strength of the composite sodium alginate film increased about 225% when the loading of MFC/C-BC biocomposite was 10 wt %. These results suggested that the MFC/C-BC biocomposite-incorporated sodium alginate film with excellent antibacterial and strength properties would be a promising material for food packaging, and the MFC/C-BC may also be a potential multifunctional biocomposite for other biodegradable materials.

  13. 21 CFR 184.1187 - Calcium alginate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Calcium alginate. 184.1187 Section 184.1187 Food... Specific Substances Affirmed as GRAS § 184.1187 Calcium alginate. (a) Calcium alginate (CAS Reg. No. 9005.... Calcium alginate is prepared by the neutralization of purified alginic acid with appropriate pH...

  14. 21 CFR 184.1724 - Sodium alginate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Sodium alginate. 184.1724 Section 184.1724 Food... GRAS § 184.1724 Sodium alginate. (a) Sodium alginate (CAS Reg. No. 9005-38-3) is the sodium salt of alginic acid, a natural polyuronide constituent of certain brown algae. Sodium alginate is prepared by...

  15. Preparation and characterization of polystyrene/Ag core-shell microspheres--a bio-inspired poly(dopamine) approach.

    PubMed

    Wang, Wencai; Jiang, Yi; Wen, Shipeng; Liu, Li; Zhang, Liqun

    2012-02-15

    A facile and versatile method using a biopolymer as a chelating agent for silver ions and as a reducing agent for the formation of catalytic sites is proposed to prepare polystyrene (PS)/Ag core-shell microspheres. More specifically, the core-shell microspheres were fabricated by electroless plating after the formation of poly(dopamine) (PDA) on the surface of PS microspheres through insitu spontaneous oxidative polymerization of dopamine. The PS-PDA microspheres were characterized by SEM, XPS, and TGA. The results showed that a uniform PDA layer was formed on the PS microsphere surface and the thickness of the PDA layer could be well controlled by varying the concentration of dopamine solution. The PDA layer was used as a chelating agent for silver ions, as a reducing agent for the formation of catalytic sites by reducing the silver ions into silver nanoparticles, and as an adhesion layer between the PS microspheres and silver layer. SEM and XRD results indicate that the diameter of the silver nanoparticles decreased with the increase in the thickness of the PDA layer. The silver nanoparticles could form a continuous and compact silver layer on the surface of the PS microspheres. Furthermore, the PS-PDA/Ag core-shell microspheres showed a good conductivity of 10S/cm and a low effective density of 1.8 g/cm(3), much lower than the corresponding values for block silver. Finally, hollow silver microspheres could be prepared by removing the PS core through calcination. SEM images showed that the hollow Ag microspheres remained unbroken and retained the spherical shape.

  16. Preparation and characterization of PHBV microsphere/45S5 bioactive glass composite scaffolds with vancomycin releasing function.

    PubMed

    Li, Wei; Ding, Yaping; Rai, Ranjana; Roether, Judith A; Schubert, Dirk W; Boccaccini, Aldo R

    2014-08-01

    PHBV microsphere/45S5 bioactive glass (BG) composite scaffolds with drug release function were developed for bone tissue engineering. BG-based glass-ceramic scaffolds with high porosity (94%) and interconnected pore structure prepared by foam replication method were coated with PHBV microspheres (nominal diameter=3.5 μm) produced by water-in-oil-in-water double emulsion solvent evaporation method. A homogeneous microsphere coating throughout the porous structure of scaffolds was obtained by a simple dip coating method, using the slurry of PHBV microspheres in hexane. Compressive strength tests showed that the microsphere coating slightly improved the mechanical properties of the scaffolds. It was confirmed that the microsphere coating did not inhibit the bioactivity of the scaffolds in SBF. Hydroxyapatite crystals homogeneously grew not only on the struts of the scaffolds but also on the surface of microspheres within 7 days of immersion in SBF. Vancomycin was successfully encapsulated into the PHBV microspheres. The encapsulated vancomycin was released with a dual release profile involving a relatively low initial burst release (21%) and a sustained release (1 month), which is favorable compared to the high initial burst release (77%) and short release period (4 days) measured on uncoated scaffolds. The developed bioactive composite scaffold with drug delivery function has thus the potential to be used advantageously in bone tissue engineering.

  17. Preparation of sustained-release nitrendipine microspheres with Eudragit RS and Aerosil using quasi-emulsion solvent diffusion method.

    PubMed

    Yang, Ming shi; Cui, Fu de; You, Ben gang; Fan, Yu ling; Wang, Liang; Yue, Peng; Yang, He

    2003-06-18

    Sustained-release nitrendipine microspheres were prepared in liquid system by quasi-emulsion solvent diffusion method, in which the Aerosil was employed as an inert dispersing carrier to improve the dissolution rate of nitrendipine, and Eudragit RS as a retarding agent to control the release rate. The resultant microspheres were evaluated for the recovery, bulk density, average particle size, drug loading, and incorporation efficiency. And the factors affecting the formation of microspheres and the drug-release rate were investigated. It was observed by a scanning electron microscope (SEM) that the microspheres were finely spherical and uniform, and no entire nitrendipine crystals were observed visually. The results of X-ray diffraction indicated that nitrendipine in microspheres was disordered, suggesting that nitrendipine was highly dispersed in microspheres. The drug loading of microspheres was enhanced with increasing the ratio of drug to excipients, and the incorporation efficiency was always >90%. The formation of microspheres was mainly influenced by the amount of bridging liquid and sodium dodecyl sulfate (SDS) in poor solvent. The dissolution profiles could be modulated with adjusting the amount of retarding agent and dispersing carrier formulated.

  18. Image analysis of lutrol/gelucire/olanzapine microspheres prepared by ultrasound-assisted spray congealing.

    PubMed

    Cavallari, Cristina; Gonzalez-Rodriguez, Marisa; Tarterini, Fabrizio; Fini, Adamo

    2014-11-01

    Nine systems were prepared containing Gelucire 50/13 and various amounts (9-18-36-45% w/w) of Lutrol F68 and F127 in the presence and in the absence of 10% w/w of olanzapine and formulated as a solid dispersion in the form of microspheres by ultrasound (US)-assisted spray congealing. Thermal analysis, using differential scanning calorimetry (DSC) and thermomicroscopy (HSM), suggested the presence of particles of reduced size of olanzapine precipitated inside the microspheres. The microspheres were also studied by means of electron microscopy (SEM) for their shape and aspect, by some image analysis parameters (fractal dimension) and using Energy-dispersive X-ray (X-EDS) and micro-Raman spectroscopy to qualitatively evaluate the composition of different points of the surface. The surface of the microspheres displayed a non-homogeneous distribution of the drug by the presence of wart-like protuberances, whose number increases as the Lutrol content of the systems increases. The same systems in the absence of US, obtained after cooling the molten mixtures, lack these structures and only a very few of them can be found. The blooming of the surface was hypothesized as related to crystallization or phase de-mixing or lipid component diffusion of the carrier mixture inside the cooling mass subjected to ultrasound vibration. Ultrasounds accelerate the physical changes concerning carriers and drug, outlining the importance of ultrasound to achieve stability for formulations of this type. The microspheres de-aggregate on contact with the dissolution medium and release the drug with a bimodal mode according to the Lutrol content.

  19. The Preparation of Chitosan Oligosaccharide/Alginate Sodium/Gelatin Nanofibers by Spiral-Electrospinning.

    PubMed

    Lu, Weipeng; Xu, Haitao; Zhang, Bing; Ma, Ming; Guo, Yanchuan

    2016-03-01

    A spiral-electrospinning was used to mass-produce gelatin nanofibers with a content of chitosan oligosaccharide (COS) and alginate sodium (AS). Multiple jets were observed to form on the edges of the helix slice-spinneret simultaneously. Important electrospinning parameters, such as concentration of COS/gelatin aqueous solution, rotational velocity of spinneret and spinning distance, were examined to investigate the electrospinnability of COS/gelatin solution and the morphology of COS/gelatin nanofiber membranes. Due to the poor miscibility between COS and AS, COS/AS/gelatin nanofiber membranes were obtained from COS/gelatin solution and AS/gelatin solution by mixing electrospinning with multi-spinnerets. The novel needleless electrospinning not only avoided the possibility of nozzle-clogging, but also prepared COS/AS/gelatin nanofibers on a large scale for a wide variety of applications.

  20. Preparation of chitosan/silk fibroin blending membrane fixed with alginate dialdehyde for wound dressing.

    PubMed

    Gu, Zhipeng; Xie, HuiXu; Huang, Chengcheng; Li, Li; Yu, Xixun

    2013-07-01

    The objective of this work was to prepare chitosan/silk fibroin (CS/SF) blending membranes crosslinked with alginate dialdehyde (ADA) as wound dressings and to evaluate the physical properties and biocompatibility of the membranes. The morphology of membrane was observed by scanning electron microscopy (SEM) which showed that the well consistency of these two compositions. Further, the stability, water absorption and water vapor permeability of the ADA fixed CS/SF membranes could meet the needs of wound dressing. Furthermore, the biocompatibility of ADA fixed membranes was investigated by MTT assays and SEM in vitro, and the membranes were found to promote the cell attachment and proliferation. These results suggest that ADA fixed CS/SF blending membranes with a suitable ratio could be a promising candidate for wound healing applications.

  1. Preparation, characterisation and viability of encapsulated Trichoderma harzianum UPM40 in alginate-montmorillonite clay.

    PubMed

    Adzmi, Fariz; Meon, Sariah; Musa, Mohamed Hanafi; Yusuf, Nor Azah

    2012-01-01

    Microencapsulation is a process by which tiny parcels of an active ingredient are packaged within a second material for the purpose of shielding the active ingredient from the surrounding environment. This study aims to determine the ability of the microencapsulation technique to improve the viability of Trichoderma harzianum UPM40 originally isolated from healthy groundnut roots as effective biological control agents (BCAs). Alginate was used as the carrier for controlled release, and montmorillonite clay (MMT) served as the filler. The encapsulated Ca-alginate-MMT beads were characterised using Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and scanning electron microscopy (SEM). The FTIR results showed the interaction between the functional groups of alginate and MMT in the Ca-alginate-MMT beads. Peaks at 1595, 1420 and 1020 cm(-1) characterised alginate, and peaks at 1028 and 453 cm(-1) characterised MMT; both sets of peaks appeared in the Ca-alginate-MMT FTIR spectrum. The TGA analysis showed an improvement in the thermal stability of the Ca-alginate-MMT beads compared with the alginate beads alone. SEM analysis revealed a homogeneous distribution of the MMT particles throughout the alginate matrix. T. harzianum UPM40 was successfully encapsulated in the Ca-alginate-MMT beads. Storage analysis of the encapsulated T. harzianum UPM40 showed that the low storage temperature of 5°C resulted in significantly (p < 0.05) better storage compared with room temperature (30°C).

  2. Determination of Ideal Broth Formulations Needed to Prepare Hydrous Aluminum Oxide Microspheres via the Internal Gelation Process

    SciTech Connect

    Collins, Jack Lee; Pye, S. L.

    2009-02-01

    A simple test-tube methodology was used to determine optimum process parameters for preparing hydrous aluminum oxide microspheres by the internal gelation process. Broth formulations of aluminum, hexamethylenetetramine, and urea were found that can be used to prepare hydrous aluminum oxide gel spheres in the temperature range of 60-90 C. A few gel-forming runs were made in which microspheres were prepared with some of these formulations in order to equate the test-tube gelation times with actual gelation times. These preparations confirmed that the test-tube methodology is reliable for determining the ideal broths.

  3. Determination of Ideal Broth Formulations Needed to Prepare Hydrous Hafnium Oxide Microspheres via the Internal Gelation Process

    SciTech Connect

    Collins, Jack Lee; Hunt, Rodney Dale; Simmerman, S. G.

    2009-02-01

    A simple test-tube methodology was used to determine optimum process parameters for preparing hydrous hafnium oxide microspheres by the internal gelation process. Broth formulations of hafnyl chloride [HfOCl{sub 2}], hexamethylenetetramine, and urea were found that can be used to prepare hydrous hafnium oxide gel spheres in the temperature range of 70-90 C. A few gel-forming runs were made in which microspheres were prepared with some of these formulations in order to equate the test-tube gelation times with actual gelation times. These preparations confirmed that the test-tube methodology is reliable for determining the ideal broths.

  4. Preparation and enhanced mechanical properties of hybrid hydrogels comprising ultralong hydroxyapatite nanowires and sodium alginate.

    PubMed

    Jiang, Ying-Ying; Zhu, Ying-Jie; Li, Heng; Zhang, Yong-Gang; Shen, Yue-Qin; Sun, Tuan-Wei; Chen, Feng

    2017-07-01

    Hydrogels with 3-dimentional cross-linked structures are widely used in various biomedical fields such as bone repair scaffolds, drug carriers and biosensors. However, the applications of hydrogels are usually restricted because of their poor mechanical properties. Currently, nanocomposites, double network systems, hydrophobic association, macromolecules, and nanoparticles are commonly adopted as cross-linking agents to enhance mechanical properties of hydrogels. In this work, ultralong hydroxyapatite nanowires (HANWs) with lengths of several hundred microns are prepared and used to enhance the mechanical properties of sodium alginate (SA)-based hydrogels. Using divalent calcium ions as the cross-linking agent, the hybrid HANWs/SA hydrogels containing various percentages of HANWs are obtained. The as-prepared HANWs/SA hybrid hydrogels have a porous structure with pore sizes ranging from about 200 to 500μm. The mechanical properties of SA hydrogels can be significantly improved by incorporating HANWs. The maximum compressive modulus (E50%) and tensile Young's modulus of the hybrid hydrogel (HANWs/SA=2:1) are as high as 0.123MPa and 0.994MPa, which are about 162% and 614% those of the pure SA hydrogel, respectively. Due to the enhanced mechanical properties and high biocompatibility, the as-prepared HANWs/SA hybrid hydrogels have promising applications in various biomedical fields such as bone defect repair.

  5. Budesonide-Loaded Guar Gum Microspheres for Colon Delivery: Preparation, Characterization and in Vitro/in Vivo Evaluation

    PubMed Central

    Liu, Ye; Zhou, Hong

    2015-01-01

    A novel budesonide (BUD) colon delivery release system was developed by using a natural polysaccharide, guar gum. The rigidity of the microspheres was induced by a chemical cross-linking method utilizing glutaraldehyde as the cross-linker. The mean particle size of the microspheres prepared was found to be 15.21 ± 1.32 µm. The drug loading and entrapment efficiency of the formulation were 17.78% ± 2.31% and 81.6% ± 5.42%, respectively. The microspheres were spherical in shape with a smooth surface, and the size was uniform. The in vitro release profiles indicated that the release of BUD from the microspheres exhibited a sustained release behavior. The model that fitted best for BUD released from the microspheres was the Higuchi kinetic model with a correlation coefficient r = 0.9993. A similar phenomenon was also observed in a pharmacokinetic study. The prolongation of the half-life (t1/2), enhanced residence time (mean residence time, MRT) and decreased total clearance (CL) indicated that BUD microspheres could prolong the acting time of BUD in vivo. In addition, BUD guar gum microspheres are thought to have the potential to maintain BUD concentration within target ranges for a long time, decreasing the side effects caused by concentration fluctuation, ensuring the efficiency of treatment and improving patient compliance by reducing dosing frequency. None of the severe signs, like the appearance of epithelial necrosis and the sloughing of epithelial cells, were detected. PMID:25629228

  6. Dextran-based hydrogel microspheres obtained in w/o emulsion: preparation, characterisation and in vivo studies.

    PubMed

    Casadei, Maria Antonietta; Cesa, Stefania; Pacelli, Settimio; Paolicelli, Patrizia; Tita, Beatrice; Vitali, Federica

    2014-01-01

    The cross-linking reaction in w/o emulsions of dextran (DEX) functionalised with methacrylic groups, having or not acid residues in side chain, can be used to easily prepare polysaccharide hydrogel microspheres with properties suitable for drug delivery applications. The formation of a chemical network within the obtained particles was evaluated with FT-IR spectroscopy, whereas morphology and dimensions of the microspheres were investigated with optical and scanning electron microscopy. At the same time, swelling measurements were carried out on freeze-dried particles in different aqueous media simulating biological fluids. Preliminary release experiments performed with ibuprofen, betamethasone and vitamin B12 chosen as model drugs, showed that these microspheres could be suitable as modified drug delivery systems in oral formulations. Finally, in vivo writhing experiments were carried out in mice in order to verify the antinociceptive activity of betamethasone loaded into the new polysaccharide hydrogel microspheres.

  7. Preparation of novel biodegradable ropivacaine microspheres and evaluation of their efficacy in sciatic nerve block in mice.

    PubMed

    Ni, Qiang; Chen, Wurong; Tong, Lei; Cao, Jue; Ji, Chao

    2016-01-01

    In this study, ropivacaine chitosan-loaded microspheres for subcutaneous administration were developed. The systems were characterized in terms of surface morphology, particle size, encapsulation efficiency, and in vitro release behavior. Results showed that the microspheres had drug loading rate of 7.3% and encapsulation efficiency of 91.2%, and their average diameter was 2.62±0.76 µm. The morphology study revealed that the microspheres are uniform monodispersed spheres and did not form aggregates in aqueous solution. It was clearly observed that the release profile of ropivacaine microspheres exhibited a biphasic pattern: the initial burst release within the first 2 hours and a following slower and sustained release over a long time. In vivo, a greater area under the plasma concentration-time curve from 0 to t (AUC0- t ) was obtained from the microspheres (4.27-fold), than from the injection group, which indicated that there was a significantly improved systemic exposure to ropivacaine. Pharmacodynamics result showed that preparing ropivacaine as microsphere preparation could not only extend the drug effect time but also decrease the administration dosage.

  8. Studies on preparation of (U0.47,Pu0.53)O2 microspheres by internal gelation process

    NASA Astrophysics Data System (ADS)

    Kumar, Ashok; Radhakrishna, J.; Kumar, N.; Pai, Rajesh V.; Dehadrai, J. V.; Deb, A. C.; Mukerjee, S. K.

    2013-03-01

    It is proposed to irradiate experimental fuel pins containing 750 μm (U0.47,Pu0.53)O2 microspheres (coarse fraction) and 110 μm UO2 microspheres (fine fraction) in the Fast Breeder Test Reactor at Kalpakkam, with a view to develop sphere-pac fuel for Fast Breeder Reactors in India. This communication describes optimization of the internal gelation process to produce dense sintered (U0.47,Pu0.53)O2 microspheres. Major modifications were incorporated in the feed preparation and the calcination and sintering steps. Use of pre-heated HMTA and urea and plutonium nitrate solution with optimum nitrate to plutonium ratio led to desired gelation kinetics and growth of crystallites which is necessary to obtain good gel microspheres. The calcination process was optimised to remove residual organics without cracking of microspheres. The studies showed that dense crack free sintered (U0.47,Pu0.53)O2 microspheres of about 98% theoretical density (TD) can be prepared using the internal gelation method.

  9. Preparation and photocatalytic properties of core-shell nano-TiO2 @ α-Al2O3 microspheres.

    PubMed

    Jing, Mao-Xiang; Han, Chong; Wang, Zhou; Shen, Xiang-Qian

    2014-09-01

    Core-shell nano-TiO2@a-Al2O3 microspheres of 5-20 μm were prepared by the heterogeneous precipitation method combined with the hydro-thermal and calcination process using α-Al2O3 microspheres as substrate. Their morphologies, microstructure and crystalline phase were characterized by SEM and XRD respectively. The photocatalytic activity was evaluated by degradation of methyl orange. The as-prepared 10 wt.% nano-TiO2@α -Al2O3 microspheres possess α core-shell structure with a monolayer of nano-TiO2 particles less than 30 nm on the surface of α-Al2O3 microspheres. Their photocatalytic properties are largely influenced by the calcination temperature and the sample calcined at 800 degrees C for 2 h has the best photocatalytic activity. This high photocatalytic activity can be attributed to the synergetic effects of the unique structure of nano-TiO2 @α-Al2O3 microspheres, quantum size effect, composition of crystalline phase and crystallinity of nano-TiO2. These nano-TiO2@α-Al2O3 microspheres may be conveniently separable and useful in practical treatment of organic waste waters due to the large particle size and high photocatalytic properties.

  10. Ultrasonic preparation of hierarchical graphene-oxide/TiO2 composite microspheres for efficient photocatalytic hydrogen production.

    PubMed

    Gao, Peng; Sun, Darren Delai

    2013-11-01

    Hierarchical graphene oxide (GO)-TiO2 composite microspheres with different GO/TiO2 mass ratios were successfully prepared by mixing GO and TiO2 microspheres under ultrasonic conditions. Ultrasonication helped the GO and TiO2 microsphere to uniformly mix on the microscale. The results showed that the GO-TiO2 composites that were prepared by ultrasonic mixing exhibited significantly higher hydrogen-evolution rates than those that were synthesized by simple mechanical grinding, owing to synergetic effects, including enhanced light absorption and scattering, as well as improved interfacial charge transfer because of the excellent contact between the GO sheets and TiO2 microspheres. In addition, GO-TiO2-3 (3 wt.% GO) showed the highest hydrogen-generation rate (305.6 μmol h(-)), which was about 13 and 3.3-times higher than those of TiO2 microsphere and GO-P25 (with 3 wt.% GO), respectively. Finally, a tentative mechanism for hydrogen production is proposed and supported by photoluminescence and transient photocurrent measurements. This work highlights the potential applications of GO-TiO2 composite microspheres in the field of clean-energy production.

  11. Novel co-axial electrohydrodynamic in-situ preparation of liquid-filled polymer-shell microspheres for biomedical applications.

    PubMed

    Farook, U; Edirisinghe, M J; Stride, E; Colombo, P

    2008-06-01

    Suspensions consisting of polymer-shelled microspheres are finding increasing use in a diverse range of technologies or applications, e.g. in the medical field, such as diagnostic imaging, drug and gene delivery and tissue engineering. In this work, a solution of water-insoluble polymethylsilsesquioxane was perfused through the outer needle of a co-axial needle arrangement while air was passed simultaneously through the inner needle, with both needles placed in an electric field. The liquid and air flow rates were varied but at 5 microl s(-1) for each material stable microbubble formation was achieved at 5.7 kV. The microbubbles were collected in a vial of distilled water and they rapidly converted into polymer-shelled microspheres containing approximately 60 wt% liquid. Microscopic examination of the spheres within 300 s of preparation showed a large population of near-spherical polymer-shelled microspheres with a mean size of 6 +/- 2 microm diameter near the water surface. After 48 h, the microspheres had collected at the bottom of the vial. The fact that the microspheres absorbed and encapsulated the liquid in which they were collected and the fact that their size (< 10 microm) is suitable for vascular administration make this a new one-step preparation technology for microspheres used in biomedical applications.

  12. Preparation of novel biodegradable ropivacaine microspheres and evaluation of their efficacy in sciatic nerve block in mice

    PubMed Central

    Ni, Qiang; Chen, Wurong; Tong, Lei; Cao, Jue; Ji, Chao

    2016-01-01

    In this study, ropivacaine chitosan-loaded microspheres for subcutaneous administration were developed. The systems were characterized in terms of surface morphology, particle size, encapsulation efficiency, and in vitro release behavior. Results showed that the microspheres had drug loading rate of 7.3% and encapsulation efficiency of 91.2%, and their average diameter was 2.62±0.76 µm. The morphology study revealed that the microspheres are uniform monodispersed spheres and did not form aggregates in aqueous solution. It was clearly observed that the release profile of ropivacaine microspheres exhibited a biphasic pattern: the initial burst release within the first 2 hours and a following slower and sustained release over a long time. In vivo, a greater area under the plasma concentration–time curve from 0 to t (AUC0–t) was obtained from the microspheres (4.27-fold), than from the injection group, which indicated that there was a significantly improved systemic exposure to ropivacaine. Pharmacodynamics result showed that preparing ropivacaine as microsphere preparation could not only extend the drug effect time but also decrease the administration dosage. PMID:27536071

  13. Immobilization of salvianolic acid B-loaded chitosan microspheres distributed three-dimensionally and homogeneously on the porous surface of hydroxyapatite scaffolds.

    PubMed

    Li, Jinyu; Wang, Qin; Zhi, Wei; Wang, Jianxin; Feng, Bo; Qu, Shuxin; Mu, Yandong; Weng, Jie

    2016-10-07

    Porous hydroxyapatite (HA) scaffolds combined with a drug delivery system have attracted much attention for bone tissue engineering. In this study, an easy and highly efficient method was developed to immobilize salvianolic acid B (Sal B)-loaded chitosan (CS) microspheres three dimensionally and homogeneously on the surface of HA scaffolds pre-coated with alginate. Porous HA scaffolds were prepared via a template-leaching process and CS microspheres (used as drug carriers) were fabricated by an emulsion method. To improve adhesion between the microspheres and HA scaffolds, alginate was used to pre-coat the porous surface of the HA scaffolds. Various concentrations of alginate were used to optimize the adhesion of Sal B-loaded CS microspheres to the scaffold surface. During the adherence process, coated HA scaffolds were immersed in an aqueous solution containing Sal B-loaded CS microspheres, followed by standing or shaking at 37 °C for a certain time. The results showed that the microspheres were solidly and homogeneously distributed on the porous surface of the alginate pre-coated HA scaffolds via electrostatic interactions. Few microspheres detached from the porous surface, even after the HA scaffolds with microspheres were treated by shaking in distilled water for as long as 7 d. Compared with the static condition, the distribution of Sal B-loaded CS microspheres on the porous surface of pre-coated HA scaffolds in the shaken condition was more homogeneous and almost unaggregated. Additionally, the compressive strength of the scaffolds coated with alginate was obviously improved. The optimal alginate coating concentration was 1% (i.e. the microstructure of the porous surfaces of the HA scaffolds was almost unchanged). The release profile of Sal B over a 30 d immersion found an initial burst release followed by a sustained release. The result of cell culture in vitro was that 1% alginate-coated scaffolds with Sal B-loaded CS microspheres obviously promoted cell

  14. Preparation and Analysis of Co-precipitated, Biodegradable Poly-(Lactide-co-Glycolide) and Polyethylene Glycol Microspheres Prepared by Spray Drying

    NASA Astrophysics Data System (ADS)

    Javiya, Curie

    Biodegradable poly-(d,l-lactide-co-glycolide) (PLGA) based microspheres are commonly used for numerous clinical applications. PEG is a widely used polymer due to its hydrophilic, biocompatible, and nontoxic nature. In this study, different blends of PLGA/PEG microspheres were prepared using a spray drying technique. The microspheres were spherical with maximum yield found to be 60.3% and average particle size in the range of 2.4 to 3.1 microm. Under the spray drying processing conditions, the polymers showed full miscibility slightly below 15% w/w and partial miscibility up to 20% w/w of PEG in the blended microspheres. At higher temperatures, PLGA and PEG were miscible in all proportions used for the blended microspheres. Blending 10% w/w PEG in PLGA membranes showed significant reduction in attachment of macrophages compared to PLGA membranes. The in-vitro response of macrophage towards the miscible blends of PLGA/PEG microspheres was further characterized. Results showed some reduction in macrophage viability and activation, however, significant effects with PLGA/PEG microspheres were not observed.

  15. Characterization of smart auto-degradative hydrogel matrix containing alginate lyase to enhance levofloxacin delivery against bacterial biofilms.

    PubMed

    Islan, German A; Dini, Cecilia; Bartel, Laura C; Bolzán, Alejandro D; Castro, Guillermo R

    2015-12-30

    The aim of the present work is the characterization of smart auto-degradable microspheres composed of calcium alginate/high methoxylated pectin containing an alginate lyase (AL) from Sphingobacterium multivorum and levofloxacin. Microspheres were prepared by ionotropic gelation containing AL in its inactive form at pH 4.0. Incubation of microspheres in Tris-HCl and PBS buffers at pH 7.40 allowed to establish the effect of ion-chelating phosphate on matrix erodability and suggested an intrinsically activation of AL by turning the pH close to neutrality. Scanning electron and optical microscopies revealed the presence of holes and surface changes in AL containing microspheres. Furthermore, texturometric parameters, DSC profiles and swelling properties were showing strong changes in microspheres properties. Encapsulation of levofloxacin into microspheres containing AL showed 70% efficiency and 35% enhancement of antimicrobial activity against Pseudomonas aeruginosa biofilm. Levofloxacin release from microspheres was not changed at acidic pH, but was modified at neutral pH in presence of AL. Advantageously, only gel matrix debris were detectable after overnight incubation, indicating an autodegradative gel process activated by the pH. Absence of matrix cytotoxicity and a reduction of the levofloxacin toxicity after encapsulation were observed in mammalian CHO-K1 cell cultures. These properties make the system a potent and versatile tool for antibiotic oral delivery targeted to intestine, enhancing the drug bioavailability to eradicate bacterial biofilm and avoiding possible intestinal obstructions.

  16. Preparation, characterization and in vitro release study of BSA-loaded double-walled glucose-poly(lactide-co-glycolide) microspheres.

    PubMed

    Ansary, Rezaul H; Rahman, Mokhlesur M; Awang, Mohamed B; Katas, Haliza; Hadi, Hazrina; Mohamed, Farahidah; Doolaanea, Abd Almonem; Kamaruzzaman, Yunus B

    2016-09-01

    The aim of this study was to prepare a model protein, bovine serum albumin (BSA) loaded double-walled microspheres using a fast degrading glucose core, hydroxyl-terminated poly(lactide-co-glycolide) (Glu-PLGA) and a moderate-degrading carboxyl-terminated PLGA polymers to reduce the initial burst release and to eliminate the lag phase from the release profile of PLGA microspheres. The double-walled microspheres were prepared using a modified water-in-oil-in-oil-in-water (w/o/o/w) method and single-polymer microspheres were prepared using a conventional water-in-oil-in-water (w/o/w) emulsion solvent evaporation method. The particle size, morphology, encapsulation efficiency, thermal properties, in vitro drug release and structural integrity of BSA were evaluated in this study. Double-walled microspheres prepared with Glu-PLGA and PLGA polymers with a mass ratio of 1:1 were non-porous, smooth-surfaced, and spherical in shape. A significant reduction of initial burst release was achieved for the double-walled microspheres compared to single-polymer microspheres. In addition, microspheres prepared using Glu-PLGA and PLGA polymers in a mass ratio of 1:1 exhibited continuous BSA release after the small initial burst without any lag phase. It can be concluded that the double-walled microspheres made of Glu-PLGA and PLGA polymers in a mass ratio of 1:1 can be a potential delivery system for pharmaceutical proteins.

  17. Preparation of sustained-release composite coating formed by dexamethasone and oxidated sodium alginate.

    PubMed

    Gao, Wenqing; Li, Tong; Yu, Meili; Hu, Xiaomin; Duan, Dawei; Lin, Tingting

    2014-01-01

    Inflammatory reaction and thrombosis are the unsolved main problems of non-coated biomaterials applied in cardiac surgery. In the present study, a series of sustained composite coating was prepared and characterized, such as in the chemical modification of polyvinyl chloride (PVC) for applications in cardiac surgery and the assessment of the biological property of modified PVC. The composite coatings were mainly formed by dexamethasone (DXM) and oxidated sodium alginate (OSA) through ionic and covalent bond methods. The biocompatibility and hemocompatibility of the coating surface were evaluated. Scanning electron microscopy analysis of the surface morphologies of the thrombus and platelets revealed that DXM-OSA coating improved the antithrombogenicity and biocompatibility of PVC circuits, which were essential for cardiac pulmonary bypass surgery. Evaluation of in vitro release revealed that the DXM on group PPC was gradually released in 8 h. Thus, DXM that covalently combined on the PVC surface showed sustained release. By contrast, DXM on groups PPI and PPD was quickly or shortly released, suggesting that groups PPI and PPD did not have sustained-release property. Overall, results indicated that the DXM-OSA composite coating may be a promising coating for the sustained delivery of DXM.

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

    PubMed

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

    2013-08-01

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

  19. Preparation and li storage properties of hierarchical porous carbon fibers derived from alginic acid.

    PubMed

    Wu, Xing-Long; Chen, Li-Li; Xin, Sen; Yin, Ya-Xia; Guo, Yu-Guo; Kong, Qing-Shan; Xia, Yan-Zhi

    2010-06-21

    One-dimensional (1D) hierarchical porous carbon fibers (HPCFs) have been prepared by controlled carbonization of alginic acid fibers and investigated with scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, nitrogen adsorption-desorption isotherms, and electrochemical tests toward lithium storage. The as-obtained HPCFs consist of a 3D network of nanosized carbon particles with diameters less than 10 nm and exhibit a hierarchical porous architecture composed of both micropores and mesopores. Electrochemical measurements show that HPCFs exhibit excellent rate capability and capacity retention compared with commercial graphite when employed as anode materials for lithium-ion batteries. At the discharge/charge rate of 45 C, the reversible capacity of HPCFs is still as high as 80 mA h g(-1) even after 1500 cycles, which is about five times larger than that of commercial graphite anode. The much improved electrochemical performances could be attributed to the nanosized building blocks, the hierarchical porous structure, and the 1D morphology of HPCFs.

  20. Preparation, characterization and pharmacokinetics of fluorescence labeled propylene glycol alginate sodium sulfate

    NASA Astrophysics Data System (ADS)

    Li, Pengli; Li, Chunxia; Xue, Yiting; Zhang, Yang; Liu, Hongbing; Zhao, Xia; Yu, Guangli; Guan, Huashi

    2014-08-01

    A rapid and sensitive fluorescence labeling method was developed and validated for the microanalysis of a sulfated polysaccharide drug,namely propylene glycol alginate sodium sulfate (PSS), in rat plasma. Fluorescein isothiocyanate (FITC) was selected to label PSS, and 1, 6-diaminohexane was used to link PSS and FITC in order to prepare FITC-labeled PSS (F-PSS) through a reductive amination reaction. F-PSS was identified by UV-Vis, FT-IR and 1H-NMR spectrum. The cell stability and cytotoxicity of F-PSS were tested in Madin-Darby canine kidney (MDCK) cells. The results indicated that the labeling efficiency of F-PSS was 0.522% ± 0.0248% and the absolute bioavailability was 8.39%. F-PSS was stable in MDCK cells without obvious cytotoxicity. The method was sensitive and reliable; it showed a good linearity, precision, recovery and stability. The FITC labeling method can be applied to investigating the absorption and metabolism of PSS and other polysaccharides in biological samples.

  1. Preparation and characterization of protein loaded microspheres based on a hydroxylated aliphatic polyester, poly(lactic-co-hydroxymethyl glycolic acid).

    PubMed

    Ghassemi, A H; van Steenbergen, M J; Talsma, H; van Nostrum, C F; Jiskoot, W; Crommelin, D J A; Hennink, W E

    2009-08-19

    The purpose of this study was to investigate the suitability of a novel hydroxylated aliphatic polyester, poly(lactic-co-hydroxymethyl glycolic acid) (PLHMGA), as controlled release system for pharmaceutical proteins. Dextran Blue (as a macromolecular model compound) and lysozyme-loaded PLHMGA and PLGA (control formulation) microspheres were prepared by a solvent evaporation technique. The Dextran Blue and lysozyme loaded PLHMGA microspheres prepared with 10% polymer solution showed, because of a high porosity, a high burst release (35-75%) and the remaining content was released in a sustained manner for 15-20 days. The microspheres prepared with 15 and 20% polymer solution had a lower porosity and showed a pulsed release after day 8 and in 27 days they released more than 90% of Blue Dextran. The release of lysozyme was incomplete, likely due to aggregation of part of the encapsulated protein. Spectroscopic analysis of the released lysozyme indicated fully preserved secondary/tertiary structure and an enzyme activity assay showed that the specific activity of the released protein was maintained. An in vitro degradation study showed that the release of Blue Dextran and lysozyme is essentially controlled by the degradation of the microspheres. This study shows that microspheres made of the hydroxylated aliphatic polyester, poly(lactic-co-hydroxymethyl glycolic acid), are promising systems for the controlled release of pharmaceutical proteins.

  2. Polyacrolein microspheres

    NASA Technical Reports Server (NTRS)

    Rembaum, Alan (Inventor)

    1986-01-01

    Microspheres of acrolein homopolymers and copolymer with hydrophillic comonomers such as methacrylic acid and/or hydroxyethylmethacrylate are prepared by cobalt gamma irradiation of dilute aqueous solutions of the monomers in presence of suspending agents, especially alkyl sulfates such as sodium dodecyl sulfate. Amine or hydroxyl modification is achieved by forming adducts with diamines or alkanol amines. Carboxyl modification is effected by oxidation with peroxides. Pharmaceuticals or other aldehyde reactive materials can be coupled to the microspheres. The microspheres directly form antibody adducts without agglomeration.

  3. Polyacrolein microspheres

    NASA Technical Reports Server (NTRS)

    Rembaum, Alan (Inventor)

    1987-01-01

    Microspheres of acrolein homopolymers and copolymer with hydrophillic comonomers such as methacrylic acid and/or hydroxyethylmethacrylate are prepared by cobalt gamma irradiation of dilute aqueous solutions of the monomers in presence of suspending agents, especially alkyl sulfates such as sodium dodecyl sulfate. Amine or hydroxyl modification is achieved by forming adducts with diamines or alkanol amines. Carboxyl modification is effected by oxidation with peroxides. Pharmaceuticals or other aldehyde reactive materials can be coupled to the microspheres. The microspheres directly form antibody adducts without agglomeration.

  4. Polyacrolein microspheres

    NASA Technical Reports Server (NTRS)

    Rembaum, Alan (Inventor)

    1983-01-01

    Microspheres of acrolein homopolymers and co-polymer with hydrophillic comonomers such as methacrylic acid and/or hydroxyethylmethacrylate are prepared by cobalt gamma irradiation of dilute aqueous solutions of the monomers in presence of suspending agents, especially alkyl sulfates such as sodium dodecyl sulfate. Amine or hydroxyl modification is achieved by forming adducts with diamines or alkanol amines. Carboxyl modification is effected by oxidation with peroxides. Pharmaceuticals or other aldehyde reactive materials can be coupled to the microspheres. The microspheres directly form antibody adducts without agglomeration.

  5. Mucoadhesive, triclosan-loaded polymer microspheres for application to the oral cavity: preparation and controlled release characteristics.

    PubMed

    Kockisch, Sandra; Rees, Gareth D; Tsibouklis, John; Smart, John D

    2005-01-01

    The aim of this study was to develop mucoadhesive microspheres that can be utilised for the controlled release of triclosan in oral-care formulations, specifically dental pastes. Using a double-emulsion solvent evaporation technique, triclosan was incorporated into microspheres that were prepared from Gantreztrade mark MS-955, Carbopol 974P, polycarbophil or chitosan and the profiles for its release were established under simulated 'in use' conditions. Triclosan was rapidly released into a sodium lauryl sulphate containing buffer from all but the chitosan microspheres. The release of triclosan from microspheres suspended in a non-aqueous paste, was found to be sustained over considerable time-periods, which were influenced strongly by the nature of the polymeric carrier. For microspheres that were fabricated from Gantrez, Carbopol or polycarbophil, the release appeared to obey zero-order kinetics whereas in the case of chitosan-derived vehicles, the release profile fitted the Baker and Lonsdale model. The work has demonstrated that these polymeric microspheres, particularly those of chitosan, are promising candidates for the sustained release of triclosan in the oral cavity.

  6. Preparation and in vitro evaluation of silk fibroin microspheres produced by a novel ultra-fine particle processing system.

    PubMed

    Wen, Xinguo; Peng, Xinsheng; Fu, Han; Dong, Yixuan; Han, Ke; Su, Jianfen; Wang, Zhouhua; Wang, Rongchang; Pan, Xin; Huang, Lin; Wu, Chuanbin

    2011-09-15

    The objective of this study was to prepare silk fibroin SF microspheres containing the enhanced green fluorescent protein (EGFP) by using a novel ultra-fine particle processing system (UPPS) and to evaluate the microspheres as possible carriers for long-term delivery of sensitive biologicals. The drug content, encapsulation efficiency, and in vitro release were evaluated by Microplate Absorbance Reader. The particle size distribution and morphology of the microspheres were analyzed by Malvern Master Sizer 2000 and scanning electron microscopy. The distribution of EGFP and the interactions between SF and EGFP were investigated by Confocal Laser Scanning Microscopy, FTIP, Raman and NMR spectroscopy. The results showed that spherical microspheres with narrow size distribution, glossy and dense surface were successfully manufactured by using UPPS technology and over 95% of EGFP encapsulation efficiency and uniform drug distribution in the microspheres were achieved. Furthermore, a burst free and sustained release of encapsulated EGFP for a period of 50 days in deionized water was obtained. In conclusion, the novel UPPS technology could be used to manufacture SF matrix microspheres as a potential long-term protein delivery system to improve patient compliance and convenience.

  7. Preparation, characterization and visible-light-driven photocatalytic activity of Fe-incorporated TiO2 microspheres photocatalysts

    NASA Astrophysics Data System (ADS)

    Li, Jun-Qi; Wang, De-Fang; Guo, Zhan-Yun; Zhu, Zhen-Feng

    2012-12-01

    Fe incorporated TiO2 microspheres (Fe-TiO2) were prepared by integrating the sol-gel method and impregnating-calcination method. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and UV-vis diffuse reflectance spectroscopy indicated that α-Fe2O3 nanoparticles were deposited onto the TiO2 microspheres, and in the mean time, some Fe3+ ions were doped into TiO2 lattice. The absorption of Fe-TiO2 microspheres in the visible light region increased with the increasing of Fe content. Photoluminescence (PL) analyses further confirmed that Fe-incorporation effectively promoted the separation and transfer of photogenerated charge carriers, which can improve the photocatalytic activity of the samples. The photocatalytic activity of Fe-TiO2 microspheres was evaluated by the degradation of methylene blue aqueous solution under visible light irradiation. The results demonstrated that the Fe-TiO2 microspheres exhibited significantly enhanced photocatalytic activity compared with pure TiO2 microspheres. What is more, the charge-transfer processes in Fe-TiO2 were also discussed.

  8. Sustained release of a water-soluble drug from alginate matrix tablets prepared by wet granulation method.

    PubMed

    Mandal, Sanchita; Basu, Sanat Kumar; Sa, Biswanath

    2009-01-01

    Alginate matrix tablet of diltiazem hydrochloride (DTZ), a water-soluble drug, was prepared using sodium alginate (SAL) and calcium gluconate (CG) by the conventional wet granulation method for sustained release of the drug. The effect of formulation variables like SAL/CG ratio, drug load, microenvironmental pH modulator, and processing variable like compression force on the extent of drug release was examined. The tablets prepared with 1:2 w/w ratio of SAL/CG produced the most sustained release of the drug extending up to 13.5 h. Above and below this ratio, the drug release was faster. The drug load and the hardness of the tablets produced minimal variation in drug release. The addition of alkaline or acidic microenvironmental modulators did not extend the release; instead, these excipients produced somewhat faster release of diltiazem. This study revealed that proper selection of SAL/CG ratio is important to produce alginate matrix tablet by wet granulation method for sustained release of DTZ.

  9. Preparation of Giant Vesicles Encapsulating Microspheres by Centrifugation of a Water-in-oil Emulsion

    PubMed Central

    Natsume, Yuno; Wen, Hsin-i; Zhu, Tong; Itoh, Kazumi; Sheng, Li; Kurihara, Kensuke

    2017-01-01

    The constructive biology and the synthetic biology approach to creating artificial life involve the bottom-up assembly of biological or nonbiological materials. Such approaches have received considerable attention in research on the boundary between living and nonliving matter and have been used to construct artificial cells over the past two decades. In particular, Giant Vesicles (GVs) have often been used as artificial cell membranes. In this paper, we describe the preparation of GVs encapsulating highly packed microspheres as a model of cells containing highly condensed biomolecules. The GVs were prepared by means of a simple water-in-oil emulsion centrifugation method. Specifically, a homogenizer was used to emulsify an aqueous solution containing the materials to be encapsulated and an oil containing dissolved phospholipids, and the resulting emulsion was layered carefully on the surface of another aqueous solution. The layered system was then centrifuged to generate the GVs. This powerful method was used to encapsulate materials ranging from small molecules to microspheres. PMID:28190062

  10. Preparation of magnetic microspheres based on poly(epsilon-caprolactone)-poly(ethylene glycol)-poly(epsilon-caprolactone) copolymers by modified solvent diffusion method.

    PubMed

    Men, Ke; Zeng, Shi; Gou, MaLing; Guo, Gang; Gu, Ying Chun; Luo, Feng; Zhao, Xia; Wei, YuQuan; Qian, ZhiYong

    2010-06-01

    Magnetic microspheres have promising application in biomedical field. In this paper, biodegradable poly(epsilon-caprolactone)-poly(ethylene glycol)-poly(epsilon-caprolactone) (PCEC) triblock copolymers were synthesized by ring-opening polymerization method. Through adjusting the epsilon-CL/PEG weight ratio in feed, PCEC copolymers with different block ratio were obtained. A novel modified solvent diffusion method was described to prepare magnetic PCEC composite microspheres containing magnetite nanoparticles. The particle size of microsphere decreased with increase in the PEG/PCL block ratio. The obtained microspheres could response to external magnetic field. This study described a novel method to prepare magnetic microspheres. The obtained magnetic polymeric microspheres might have potential application in drug delivery system or disease diagnosis field.

  11. Preparation of hollow porous Cu2O microspheres and photocatalytic activity under visible light irradiation

    PubMed Central

    2012-01-01

    Cu2O p-type semiconductor hollow porous microspheres have been prepared by using a simple soft-template method at room temperature. The morphology of as-synthesized samples is hollow spherical structures with the diameter ranging from 200 to 500 nm, and the surfaces of the spheres are rough, porous and with lots of channels and folds. The photocatalytic activity of degradation of methyl orange (MO) under visible light irradiation was investigated by UV-visible spectroscopy. The results show that the hollow porous Cu2O particles were uniform in diameters and have an excellent ability in visible light-induced degradation of MO. Meanwhile, the growth mechanism of the prepared Cu2O was also analyzed. We find that sodium dodecyl sulfate acted the role of soft templates in the synthesis process. The hollow porous structure was not only sensitive to the soft template but also to the amount of reagents. PMID:22738162

  12. Pitch carbon microsphere composite

    NASA Technical Reports Server (NTRS)

    Price, H. L.; Nelson, J. B.

    1977-01-01

    Petroleum pitch carbon microspheres were prepared by flash heating emulsified pitch and carbonizing the resulting microspheres in an inert atmosphere. Microsphere composites were obtained from a mixture of microspheres and tetraester precursor pyrrone powder. Scanning electron micrographs of the composite showed that it was an aggregate of microspheres bonded together by the pyrrone at the sphere contact points, with voids in and among the microspheres. Physical, thermal, and sorption properties of the composite are described. Composite applications could include use as a honeycomb filler in elevated-temperature load-bearing sandwich boards or in patient-treatment tables for radiation treatment of tumors.

  13. Emulsification/internal gelation as a method for preparation of diclofenac sodium-sodium alginate microparticles.

    PubMed

    Ahmed, Mahmoud M; El-Rasoul, Saleh Abd; Auda, Sayed H; Ibrahim, Mohamed A

    2013-01-01

    Emulsification/internal gelation has been suggested as an alternative to extrusion/external gelation in the encapsulation of several compounds including non-steroidal anti-inflammatory drugs such as diclofenac sodium. The objective of the present study was a trial to formulate diclofenac sodium as controlled release microparticles that might be administered once or twice daily. This could be achieved via emulsification/internal gelation technique applying Box-Behnken design to choose these formulae. Box-Behnken design determined fifteen formulae containing specified amounts of the independent variables, which included stirring speed in rpm (X1), drug:polymer ratio (X2) and the surfactant span 80% (X3). The dependent variables studied were cumulative percent release after two hours (Y1), four hours (Y2) and eight hours (Y3). The prepared microparticles were characterized for their production yield, sizes, shapes and morphology, entrapment efficiency and Diclofenac sodium in vitro release as well. The results showed that the production yield of the prepared diclofenac sodium microparticles was found to be between 79.55% and 97.41%. The formulated microparticles exhibited acceptable drug content values that lie in the range 66.20-96.36%. Also, the data obtained revealed that increasing the mixing speed (X1) generally resulted in decreased microparticle size. In addition, scanning electron microscope images of the microparticles illustrated that the formula contains lower span concentration (1%) in combination with lower stirring speed (200 rpm) which showed wrinkled, but smooth surfaces. However, by increasing surfactant concentration, microspheres' surfaces become smoother and slightly porous. Kinetic treatment of the in vitro release from drug-loaded microparticles indicated that the zero order is the drug release mechanism for the most formulae.

  14. Polypropylene nonwoven surface modified through introducing porous microspheres: Preparation, characterization and adsorption

    NASA Astrophysics Data System (ADS)

    Du, Xiao; Wei, Junfu; Liu, Wei; Zhou, Xiangyu; Dai, Danyang

    2016-01-01

    A new porous fabric adsorbent (PM/PP nonwoven) was prepared by hydrogen bonding self-assembly method, in which poly(divinylbenzene-co-4-vinylpyridine) microspheres were introduced onto the surface of PP-g-AA (polypropylene grafted acrylic acid) nonwoven. The effects of the main conditions for self-assembly reaction such as mass ratio of microsphere to nonwoven, pH and the grafting degree of acrylic acid were studied. In addition, the adsorption mechanisms and interactions for three VOCs (styrene, cyclohexane, acetone) were systematically elucidated. The resulting 28.2% PM/PP nonwoven obtained a higher adsorption amount (52.8 mg/g) of styrene vapor, which was 88 times greater than that of original PP nonwoven. Meanwhile, the kinetic studies suggested that the Yoon and Nelson model is suitable to describe the adsorption mechanism of styrene over the modified nonwovens. Adsorption and pressure drop data showed that PM/PP nonwoven had good adsorption ability and air permeability due to its abundant functional groups and porous structures. Taken together, it is expected that PM/PP nonwoven would be a promising adsorbent for removal of VOCs from the gas streams.

  15. Preparation, characterization and applications of low-molecular-weight alginate-oligochitosan nanocapsules

    NASA Astrophysics Data System (ADS)

    Wang, Ting; He, Nongyue

    2010-02-01

    The development of drug-delivering nanoparticles from natural materials for various biomedical applications is an area of great promise. However, the contradictory data on their uncontrollable diameter, unstable structure and toxic effects, highlight the need to study their preparation, characterization and cytotoxic effects in cells. In this work, nanocapsules are made from a type of W/O microemulsion system with low-molecular-weight alginate (LMWALG) and oligochitosan (OCS). The particles possess excellent biocompatibility and good biodegradability. The size of capsules is controlled and optimized by carefully adjusting the molecular weight and concentration of LMWALG and OCS. We found, from orthogonal experiments, the encapsulation time leading to a uniform size distribution with an average diameter of 136 nm. Furthermore, we found that molecular weights of LMWALG and OCS significantly influence the stability and size of capsules. The optimized nanocapsules are further used to study the drug release of BSA. Results show that the efficiency of encapsulation approximately reaches 88.4% and the concentration of BSA in phosphate-buffered solution (PBS, pH = 7.4) is well maintained at a level of 35 to 40% from 12 h to 48 h, due to the stable and slow degradation of the nanocapusules. The biocompatibility of LMWALG/OCS nanocapsules is cross-examined by cytotoxicity experiments and acute systemic toxicological tests, and they were found to enhance the survival rate of the cells from 80.30 to 95.39% in 7 days. The synthesized nanocapsules exhibit high biocompatibility, non-toxicity, biodegradation, and uniform size, providing a new potential candidate for drug releases in clinic experiments.

  16. Preparation and application of agar/alginate/collagen ternary blend functional food packaging films.

    PubMed

    Wang, Long-Feng; Rhim, Jong-Whan

    2015-09-01

    Ternary blend agar/alginate/collagen (A/A/C) hydrogel films with silver nanoparticles (AgNPs) and grapefruit seed extract (GSE) were prepared. Their performance properties, transparency, tensile strength (TS), water vapor permeability (WVP), water contact angle (CA), water swelling ratio (SR), water solubility (WS), and antimicrobial activity were determined. The A/A/C film was highly transparent, and both AgNPs and GSE incorporated blend films (A/A/C(AgNPs) and A/A/C(GSE)) exhibited UV-screening effect, especially, the A/A/C(GSE) film had high UV-screening effect without sacrificing the transmittance. In addition, the A/A/C blend films formed efficient hydrogel film with the water holding capacity of 23.6 times of their weight. Both A/A/C(AgNPs) and A/A/C(GSE) composite films exhibited strong antimicrobial activity against both Gram-positive (Listeria monocytogenes) and Gram-negative (Escherichia coli) food-borne pathogenic bacteria. The test results of fresh potatoes packaging revealed that all the A/A/C ternary blend films prevented forming of condensed water on the packaged film surface, both A/A/C(AgNPs) and A/A/C(GSE) composite films prevented greening of potatoes during storage. The results indicate that the ternary blend hydrogel films incorporated with AgNPs or GSE can be used not only as antifogging packaging films for highly respiring fresh agriculture produce, but also as an active food packaging system utilizing their strong antimicrobial activity.

  17. Prediction of dexamethasone release from PLGA microspheres prepared with polymer blends using a design of experiment approach.

    PubMed

    Gu, Bing; Burgess, Diane J

    2015-11-10

    Hydrophobic drug release from poly (lactic-co-glycolic acid) (PLGA) microspheres typically exhibits a tri-phasic profile with a burst release phase followed by a lag phase and a secondary release phase. High burst release can be associated with adverse effects and the efficacy of the formulation cannot be ensured during a long lag phase. Accordingly, the development of a long-acting microsphere product requires optimization of all drug release phases. The purpose of the current study was to investigate whether a blend of low and high molecular weight polymers can be used to reduce the burst release and eliminate/minimize the lag phase. A single emulsion solvent evaporation method was used to prepare microspheres using blends of two PLGA polymers (PLGA5050 (25 kDa) and PLGA9010 (113 kDa)). A central composite design approach was applied to investigate the effect of formulation composition on dexamethasone release from these microspheres. Mathematical models obtained from this design of experiments study were utilized to generate a design space with maximized microsphere drug loading and reduced burst release. Specifically, a drug loading close to 15% can be achieved and a burst release less than 10% when a composition of 80% PLGA9010 and 90 mg of dexamethasone is used. In order to better describe the lag phase, a heat map was generated based on dexamethasone release from the PLGA microsphere/PVA hydrogel composite coatings. Using the heat map an optimized formulation with minimum lag phase was selected. The microspheres were also characterized for particle size/size distribution, thermal properties and morphology. The particle size was demonstrated to be related to the polymer concentration and the ratio of the two polymers but not to the dexamethasone concentration.

  18. PREPARATION OF FLOWER-LIKE Co3O4/Fe3O4 MAGNETIC MICROSPHERES FOR PHOTODEGRADATION OF RhB UNDER UV LIGHT

    NASA Astrophysics Data System (ADS)

    Zhang, Baoliang; Zhang, Hepeng; Zhou, Lunwei; Ali, Nisar; Geng, Wangchang; Zhang, Qiuyu

    2013-07-01

    Flower-like Co3O4/Fe3O4 magnetic microspheres were prepared by coprecipitation of Fe2+ and Fe3+ in presence of flower-like Co3O4 microspheres as template. The preparation process included three steps: preparation of flower-like Co3O4 microspheres by hydrothermal method; immersion of Fe2+ and Fe3+ ions; coprecipitation in the presence of OH-. Rhodamine B (RhB) was chosen as model pollutants to investigate the photodegradation capacities of Co3O4/Fe3O4 magnetic microspheres. The results showed that the microspheres exhibited excellent degradation property and can be recycled to use again. After four times use the degradation efficiency was still above 90%.

  19. The Preparation of Capsaicin-Chitosan Microspheres (CCMS) Enteric Coated Tablets

    PubMed Central

    Chen, Jian; Huang, Gui-Dong; Tan, Si-Rong; Guo, Jiao; Su, Zheng-Quan

    2013-01-01

    This study aimed to research the preparation and content determination of capsaicin-chitosan microspheres (CCMS) enteric coated tablets. The core tablets were prepared with the method of wet granulation. Nine formulae were designed to determine the optimal formula of the core tablet. Eudragit L100 was used to prepare the CCMS enteric-coated tablets. The effect of enteric coated formulation variables such as content of talc (10%, 25% and 40%), plasticisers (TEC and DBS), dosage of plasticiser (10%, 20% and 30%) and coating weight (2%, 3% and 5%) were evaluated for drug release characteristics. The in vitro release was studied using 0.1 N HCl and pH 6.8 phosphate buffer. Enteric coated tablets without ruptures or swelling behaviour over 2 h in 0.1 N HCl indicated that these tablets showed acid resistance. The accumulated release rate in phosphate buffer (pH 6.8) revealed that the prepared tablets were able to sustain drug release into the intestine and a first-order release was obtained for capsaicin. This research is the first report of the preparation and content determination of CCMS enteric coated tablets. The sustained release behavior of enteric coated formulations in pH 6.8 phosphate buffer demonstrated that it would be a potential drug delivery platform for sustained delivery of gastric irritant drugs. PMID:24351818

  20. The preparation of capsaicin-chitosan microspheres (CCMS) enteric coated tablets.

    PubMed

    Chen, Jian; Huang, Gui-Dong; Tan, Si-Rong; Guo, Jiao; Su, Zheng-Quan

    2013-12-13

    This study aimed to research the preparation and content determination of capsaicin-chitosan microspheres (CCMS) enteric coated tablets. The core tablets were prepared with the method of wet granulation. Nine formulae were designed to determine the optimal formula of the core tablet. Eudragit L100 was used to prepare the CCMS enteric-coated tablets. The effect of enteric coated formulation variables such as content of talc (10%, 25% and 40%), plasticisers (TEC and DBS), dosage of plasticiser (10%, 20% and 30%) and coating weight (2%, 3% and 5%) were evaluated for drug release characteristics. The in vitro release was studied using 0.1 N HCl and pH 6.8 phosphate buffer. Enteric coated tablets without ruptures or swelling behaviour over 2 h in 0.1 N HCl indicated that these tablets showed acid resistance. The accumulated release rate in phosphate buffer (pH 6.8) revealed that the prepared tablets were able to sustain drug release into the intestine and a first-order release was obtained for capsaicin. This research is the first report of the preparation and content determination of CCMS enteric coated tablets. The sustained release behavior of enteric coated formulations in pH 6.8 phosphate buffer demonstrated that it would be a potential drug delivery platform for sustained delivery of gastric irritant drugs.

  1. Preparation, characterization, and sensing behavior of polydiacetylene liposomes embedded in alginate fibers.

    PubMed

    Kauffman, Jennifer S; Ellerbrock, Brett M; Stevens, Kathryn A; Brown, Philip J; Pennington, William T; Hanks, Timothy W

    2009-06-01

    Polydiacetylene (PDA)-doped calcium alginate fibers were created by the solution blending of polymerized 10,12-pentacosadiynoic acid liposomes with sodium alginate in water prior to extrusion. The liposomes maintained their blue color during wet spinning and drying of the fibers but changed to red with exposure to specific external stimuli (heat, solvent, and chemical). In the latter case, the color change only occurred when the fibers were sufficiently permeable for the reacting species to reach the interior. A parameter termed the "Raman response" (RR) has been developed to quantify the amount of PDA liposomes in each of two critical conformations within the fibers. The RR attributes a quantitative measure of PDA response to individual stimuli. This method provides advantages over the commonly used "colorimetric response" in systems where sample limitations and chromophore activity make UV-vis spectroscopic measurements difficult or inaccurate. PDA liposomes are shown to effectively add a versatile sensing component to alginate fibers.

  2. Preparation and characterization of. beta. -D-glucosidase immobilized in calcium alginate

    SciTech Connect

    Krasniak, S. R.; Smith, R. D.

    1982-01-01

    Enzymatic hydrolysis of biomass to produce glucose may become feasible if an inexpensive method to reuse the enzyme can be found. This study investigated one such method whereby ..beta..-D-glucosidase (E.C. 3.2.1.21) was immobilized in calcium alginate gel spheres, which were shown to catalyze the hydrolysis of cellobiose to glucose. There was a loss of 49% of the enzyme from the alginate slurry during gelation. After gelation, in the stable gel spheres, there was a 37% retention of the enzyme activity that was actually immobilized. The reason for the loss in activity was investigated and may be caused by inhibition of the enzyme within the sphere by the calcium cations and the alginate anions also present. Mass transfer effects were minimal in this system and were not responsible for the activity loss.

  3. Preparation and characterization of enteric microspheres containing bovine insulin by a w/o/w emulsion solvent evaporation method.

    PubMed

    Nagareya, N; Uchida, T; Matsuyama, K

    1998-10-01

    The objective of this study was to produce enteric microspheres containing bovine insulin as a model drug using a water-in-oil-in-water (w/o/w) emulsion solvent evaporation method, and the preparative conditions were optimized. When hydroxypropylmethylcellulose acetate succinate (AS-HG type; high content of succinyl group) was employed as an enteric wall material, optimized microspheres showed almost 90% of the loading efficiency of insulin and 30.8 microns of mean volume diameter. The mixture of methylene chloride and acetone (4:1) as an oleaginous phase, 400 microliters of bovine insulin solution (dissolved in 30% of acetic acid) as an internal aqueous phase, and 1.0% of polyvinylalcohol dissolved in pH 3.0 citrate buffer as an external aqueous phase, were employed in the experiment. In relation to other enteric cellulose derivatives (AS-MG type, AS-LG type; medium and low content of succinyl group, respectively), the microencapsulation using a simultaneous preparation method also resulted in quite high loading efficiencies, whereas the choice of poly(methyl methacrylate) as a wall material caused aggregation or flocculation in the preparative process of every batch. The AS-HG microspheres showed very fast release profile in pH 6.8 buffer, but no released fraction was observed in pH 1.2 buffer. This phenomenon suggested enteric characteristics of prepared microspheres. Finally AS-HG microspheres containing 4% lauric acid and 9% insulin were prepared, suspended in 0.1% of carboxymethyl cellulose solution, and administered to the rat rectum (corresponding to 50 I.U./kg insulin). The plasma glucose level reached minimum level at 0.5 h after administration then gradually rose to normal.

  4. Biomass Vanillin-Derived Polymeric Microspheres Containing Functional Aldehyde Groups: Preparation, Characterization, and Application as Adsorbent.

    PubMed

    Zhang, Huanyu; Yong, Xueyong; Zhou, Jinyong; Deng, Jianping; Wu, Youping

    2016-02-03

    The contribution reports the first polymeric microspheres derived from a biomass, vanillin. It reacted with methacryloyl chloride, providing monomer vanillin methacrylate (VMA), which underwent suspension polymerization in aqueous media and yielded microspheres in high yield (>90 wt %). By controlling the N2 bubbling mode and by optimizing the cosolvent for dissolving the solid monomer, the microspheres were endowed with surface pores, demonstrated by SEM images and mercury intrusion porosimetry measurement. Taking advantage of the reactive aldehyde groups, the microspheres further reacted with glycine, thereby leading to a novel type of Schiff-base chelating material. The functionalized microspheres demonstrated remarkable adsorption toward Cu(2+) (maximum, 135 mg/g) which was taken as representative for metal ions. The present study provides an unprecedented class of biobased polymeric microspheres showing large potentials as adsorbents in wastewater treatment. Also importantly, the reactive aldehyde groups may enable the microspheres to be used as novel materials for immobilizing biomacromolecules, e.g. enzymes.

  5. (90)Y microspheres prepared by sol-gel method, promising medical material for radioembolization of liver malignancies.

    PubMed

    Łada, Wiesława; Iller, Edward; Wawszczak, Danuta; Konior, Marcin; Dziel, Tomasz

    2016-10-01

    A new technology for the production of radiopharmaceutical (90)Y microspheres in the form of spherical yttrium oxide grains obtained by sol-gel method has been described. The authors present and discuss the results of investigations performed in the development of new production technology of yttrium microspheres and determination of their physic-chemical properties. The final product has the structure of spherical yttrium oxide grains with a diameter 25-100μm, is stable and free from contaminants. Irradiation of 20mg samples of grains with diameter of 20-50μm in the thermal neutron flux of 1.7×10(14)cm(-2)s(-1) at the core of MARIA research nuclear reactor allowed to obtain microspheres labelled with the (90)Y isotope on the way of the nuclear reaction (89)Y(n, ɤ)(90)Y. Specific activity of irradiated microspheres has been determined by application of absolute triple to double coincidence ratio method (TDCR) and has been evaluated at 190MBq/mg Y. (90)Y microspheres prepared by the proposed technique can be regarded as a promising medical material for radioembolization of liver malignancies.

  6. Determination of Ideal Broth Formulations Needed to Prepare Hydrous Cerium Oxide Microspheres via the Internal Gelation Process

    SciTech Connect

    Collins, Jack Lee; Chi, Anthony

    2009-02-01

    A simple test tube methodology was used to determine optimum process parameters for preparing hydrous cerium oxide microspheres via the internal gelation process.1 Broth formulations of cerium ammonium nitrate [(NH4)2Ce(NO3)6], hexamethylenetetramine, and urea were found that can be used to prepare hydrous cerium oxide gel spheres in the temperature range of 60 to 90 C. A few gel-forming runs were made in which microspheres were prepared with some of these formulations to be able to equate the test-tube gelation times to actual gelation times. These preparations confirmed that the test-tube methodology is reliable for determining the ideal broth formulations.

  7. Preparation of porous nitrogen-doped titanium dioxide microspheres and a study of their photocatalytic, antibacterial and electrochemical activities

    SciTech Connect

    Chen, S.; Chu, W.; Huang, Y.Y.; Liu, X.; Tong, D.G.

    2012-12-15

    Graphical abstract: Porous N-doped TiO{sub 2} microspheres were prepared for the first time via plasma technique. The sample exhibited better photocatalytic activity, photoinduced inactivation activity and better electrochemical activity than those of TiO{sub 2} microspheres and P25. Display Omitted Highlights: ► Porous N-doped TiO{sub 2} microspheres were prepared via nitrogen plasma technique. ► Plasma treatment did not affect the porous structure of the TiO{sub 2} microspheres. ► With the plasma treatment, the N contents in the samples increased. ► Their photocatalytic, antibacterial and electrochemical activities were studied. -- Abstract: Nitrogen-doped titanium dioxide (N-doped TiO{sub 2}) microspheres with porous structure were prepared via the nitrogen-assisted glow discharge plasma technique at room temperature for the first time. The samples were characterized by X-ray diffraction, scanning electron microscopy, nitrogen adsorption–desorption measurement, UV–Vis diffuse reflectance spectra, photoluminescence spectroscopy and X-ray photoelectron spectroscopy. The results indicated that the plasma treatment did not affect the porous structure of the TiO{sub 2} microspheres. With the plasma treatment, the N contents in the samples increased. During the photocatalytic degradation of methylene blue under simulative sunlight irradiation, the sample after plasma treatment for 60 min (N-TiO{sub 2}-60) exhibited higher photocatalytic activity than those of the TiO{sub 2} microspheres, P25 and other N-doped TiO{sub 2} microspheres. Furthermore, the N-TiO{sub 2}-60 showed excellent antibacterial activities towards Escherichia coli under visible irradiation. These should be attributed to the enhancement of the visible light region absorption for TiO{sub 2} after N-doping. Electrochemical data demonstrated that the N-doping not only enhanced the electrochemical activity of TiO{sub 2}, but also improved the reversibility of Li insertion/extraction reactions

  8. Design and preparation of film for microsphere based optical super-resolution imaging

    NASA Astrophysics Data System (ADS)

    Pang, Hui; Du, Chunlei; Qiu, Qi; Yin, Shaoyun; Zhang, Man; Deng, Qiling

    2014-08-01

    In this paper, a novel thin film was proposed for optical super-resolution imaging, which contains a layer of closely-arranged barium titanate glass microsphere with diameter about 30-100μm embedded in a transparent polydimethylsiloxane soft mold. Then the imaging mechanism was analyzed by the finite-difference time-domain (FDTD) simulation and spectrum analysis method. Finally, the thin film was prepared and used to image the sample with sub-wavelength feature to confirm the capability of super-resolution imaging. The experimental result shows that an irresolvable Blu-ray DVD disk with feature size of 300nm can be resolved by placing a thin-film on its surface and then look through it with a conventional microscope. The thin film presented here is flexible, lightweight, easy to carry and can be used in the nanophotonics, nanoplasmonics, and biomedical imaging areas.

  9. Preparation and evaluation of Levosalbutamol sulphate chitosan microsphere for the treatment of asthma

    PubMed Central

    Patel, D. Dinal; Patel, V. Nirav; Thakkar, T. Vaishali; Gandhi, R. Tejal

    2012-01-01

    Mucoadhesive drug delivery systems are those that provide intimate contact of the drug with the mucosa for an extended period of time. In present work, mucoadhesive chitosan microspheres of Levosalbutamol sulphate were prepared by Spray drying method. Formulations were characterized for various physicochemical attributes size, encapsulation efficiency, swelling ability, in vitro release study and mucoadhesion study by rat ileum. Through these parameters we conclude that the batch B2 was found to be best mainly by mucoadhesion study and in vitro drug release. Mucoadhesion was found to be increased with incresed concentration of polymer and visa versa in case of drug release. Batch B3 had also similar results with that of Batch B2. That's why here Batch B2 was said to be the best batch with less polymeric content as compare to Batch B3. PMID:23066203

  10. Preparation and evaluation of Levosalbutamol sulphate chitosan microsphere for the treatment of asthma.

    PubMed

    Patel, D Dinal; Patel, V Nirav; Thakkar, T Vaishali; Gandhi, R Tejal

    2012-03-01

    Mucoadhesive drug delivery systems are those that provide intimate contact of the drug with the mucosa for an extended period of time. In present work, mucoadhesive chitosan microspheres of Levosalbutamol sulphate were prepared by Spray drying method. Formulations were characterized for various physicochemical attributes size, encapsulation efficiency, swelling ability, in vitro release study and mucoadhesion study by rat ileum. Through these parameters we conclude that the batch B(2) was found to be best mainly by mucoadhesion study and in vitro drug release. Mucoadhesion was found to be increased with incresed concentration of polymer and visa versa in case of drug release. Batch B(3) had also similar results with that of Batch B(2). That's why here Batch B(2) was said to be the best batch with less polymeric content as compare to Batch B(3).

  11. Facile approach to prepare hollow core–shell NiO microspherers for supercapacitor electrodes

    SciTech Connect

    Han, Dandan; Xu, Pengcheng; Jing, Xiaoyan; Wang, Jun; Song, Dalei; Liu, Jingyuan; Zhang, Milin

    2013-07-15

    A facile lamellar template method (see image) has been developed for the preparation of uniform hollow core–shell structure NiO (HCS–NiO) with a nanoarchitectured wall structure. The prepared NiO was found to be highly crystalline in uniform microstructures with high specific surface area and pore volume. The results indicated that ethanol interacted with trisodium citrate played an important role for the formation of hollow core–shell spheres. On the basis of the analysis of the composition and the morphology, a possible formation mechanism was investigated. NiO microspheres with hollow core–shell showed excellent capacitive properties. The exceptional cyclic, structural and electrochemical stability with ∼95% coulombic efficiency, and very low ESR value from impedance measurements promised good utility value of hollow core–shell NiO material in fabricating a wide range of high-performance electrochemical supercapacitors. - The hollow core–shell NiO was prepared with a facile lamellar template method. The prepared NiO show higher capacitance, lower ion diffusion resistance and better electroactive surface utilization for Faradaic reactions. - Highlights: • Formation of hollow core–shell NiO via a novel and facile precipitation route. • Exhibited uniform feature sizes and high surface area of hollow core–shell NiO. • Synthesized NiO has high specific capacitance ( 448 F g{sup 1}) and very low ESR value. • Increased 20% of long life cycles capability after 500 charge–discharge cycles.

  12. Preparation and characterization of hydroxyapatite/sodium alginate biocomposites for bone implant application

    NASA Astrophysics Data System (ADS)

    Kanasan, Nanthini; Adzila, Sharifah; Suid, Mohd Syafiq; Gurubaran, P.

    2016-07-01

    In biomedical fields, synthetic scaffolds are being improved by using the ceramics, polymers and composites materials to avoid the limitations of allograft. Ceramic-polymer composites are appearing to be the most successful bone graft substitute in human body. The natural bones itself are well-known as composite of collagen and hydroxyapatite. In this research, precipitation method was used to synthesis hydroxyapatite (HA)/sodium alginate (SA) in various parameters. This paper describes the hydroxyapatite/sodium alginate biocomposite which suitable for use in bone defects or regeneration of bone through the characterizations which include FTIR, FESEM, EDS and DTA. In FTIR, the characteristi peaks of PO4-3 and OH- groups which corresponding to hydroxyapatite are existed in the mixing powders. The needle-size particle of hydroxyapatite/ alginate (HA/SA) are observed in FESEM in the range of 15.8nm-38.2nm.EDS confirmed the existence of HA/SA composition in the mixing powders. There is an endothermic peak which corresponds to the dehydration and the loss of physically adsorbed water molecules of the hydroxyapatite (HA)/sodium alginate (SA) powder which are described in DTA.

  13. Physicochemical Characterization of a Heat Treated Calcium Alginate Dry Film Prepared with Chicken Stock.

    PubMed

    Báez, Germán D; Piccirilli, Gisela N; Ballerini, Griselda A; Frattini, Agustín; Busti, Pablo A; Verdini, Roxana A; Delorenzi, Néstor J

    2017-04-01

    Solid sodium alginate was dissolved into chicken stock in order to give a final alginate concentration of 0.9 percent (w/v). Calcium ions present in chicken stock were enough to induce ionic gelation. After drying, Fourier transform infrared spectroscopy, thickness and mechanical properties of films obtained were determined. Calcium alginate-chicken stock films were heated at 130 °C for different times between 0 and 15 min. Mechanical and optical studies, differential scanning calorimetry, visual aspect and scanning electron microscopy were carried out to describe physicochemical properties of heat treated films. Heating developed a maroon ochre color and increased the brittleness (crispness) of the films related to the intensity of the treatment. Differential scanning thermometry and study on appearance of the films suggested that Maillard reactions may be responsible for the observed changes. Maillard reactions mainly occurred between reducing sugar monomers and free amino groups of gelatin peptides present in the chicken stock, and between alginate and gelatin peptides to a lesser extent. In addition, the plasticizing effect of fat added with chicken stock was also studied. These studies suggest a potential use of heat treated chicken stock films as a substitute of roasted chicken skin.

  14. Photochemical preparation of CdS hollow microspheres at room temperature and their use in visible-light photocatalysis

    SciTech Connect

    Huang Yuying; Sun Fengqiang; Wu Tianxing; Wu Qingsong; Huang Zhong; Su Heng; Zhang Zihe

    2011-03-15

    CdS hollow microspheres have been successfully prepared by a photochemical preparation technology at room temperature, using polystyrene latex particles as templates, CdSO{sub 4} as cadmium source and Na{sub 2}S{sub 2}O{sub 3} as both sulphur source and photo-initiator. The process involved the deposition of CdS nanoparticles on the surface of polystyrene latex particles under the irradiation of an 8 W UV lamp and the subsequent removal of the latex particles by dispersing in dichloromethane. Photochemical reactions at the sphere/solution interface should be responsible for the formation of hollow spheres. The as-prepared products were characterized by X-ray diffraction, transmission electron microscopy and scanning electron microscopy. Such hollow spheres could be used in photocatalysis and showed high photocatalytic activities in photodegradation of methyl blue (MB) in the presence of H{sub 2}O{sub 2}. The method is green, simple, universal and can be extended to prepare other sulphide and oxide hollow spheres. -- Graphical abstract: Taking polystyrene spheres dispersed in a precursor solution as templates, CdS hollow microspheres composed of nanoparticles were successfully prepared via a new photochemical route at room temperature. Display Omitted Research highlights: {yields} Photochemical method was first employed to prepare hollow microspheres. {yields} CdS hollow spheres were first prepared at room temperature using latex spheres. {yields} The polystyrene spheres used as templates were not modified with special groups. {yields}The CdS hollow microspheres showed high visible-light photocatalytic activities.

  15. Preparation of monodisperse PEG hydrogel composite microspheres via microfluidic chip with rounded channels

    NASA Astrophysics Data System (ADS)

    Yu, Bing; Cong, Hailin; Liu, Xuesong; Ren, Yumin; Wang, Jilei; Zhang, Lixin; Tang, Jianguo; Ma, Yurong; Akasaka, Takeshi

    2013-09-01

    An effective microfluidic method to fabricate monodisperse polyethylene glycol (PEG) hydrogel composite microspheres with tunable dimensions and properties is reported in this paper. A T-junction microfluidic chip equipped with rounded channels and online photopolymerization system is applied for the microsphere microfabrication. The shape and size of the microspheres are well controlled by the rounded channels and PEG prepolymer/silicon oil flow rate ratios. The obtained PEG/aspirin composite microspheres exhibit a sustained release of aspirin for a wide time range; the obtained PEG/Fe3O4 nanocomposite microspheres exhibit excellent magnetic properties; and the obtained binary PEG/dye composite microspheres show the ability to synchronously load two functional components in the same peanut-shaped or Janus hydrogel particles.

  16. Preparation and characterization of monodisperse large-porous silica microspheres as the matrix for protein separation.

    PubMed

    Xia, Hongjun; Wan, Guangping; Zhao, Junlong; Liu, Jiawei; Bai, Quan

    2016-11-04

    High performance liquid chromatography (HPLC) is a kind of efficient separation technology and has been used widely in many fields. Micro-sized porous silica microspheres as the most popular matrix have been used for fast separation and analysis in HPLC. In this paper, the monodisperse large-porous silica microspheres with controllable size and structure were successfully synthesized with polymer microspheres as the templates and characterized. First, the poly(glycidyl methacrylate-co-ethyleneglycol dimethacrylate) microspheres (PGMA-EDMA) were functionalized with tetraethylenepentamine (TEPA) to generate amino groups which act as a catalyst in hydrolysis of tetraethyl orthosilicate (TEOS) to form Si-containing low molecular weight species. Then the low molecular weight species diffused into the functionalized PGMA-EDMA microspheres by induction force of the amino groups to form polymer/silica hybrid microspheres. Finally, the organic polymer templates were removed by calcination, and the large-porous silica microspheres were obtained. The compositions, morphology, size distribution, specific surface area and pore size distribution of the porous silica microspheres were characterized by infrared analyzer, scanning-electron microscopy, dynamic laser scattering, the mercury intrusion method and thermal gravimetric analysis, respectively. The results show that the agglomeration of the hybrid microspheres can be overcome when the templates were functionalized with TEPA as amination reagent, and the yield of 95.7% of the monodisperse large-porous silica microspheres can be achieved with high concentration of polymer templates. The resulting large-porous silica microspheres were modified with octadecyltrichlorosilane (ODS) and the chromatographic evaluation was performed by separating the proteins and the digest of BSA. The baseline separation of seven kinds of protein standards was achieved, and the column delivered a better performance when separating BSA digests

  17. Preparation and in vitro release performance of sustained-release captopril/Chitosan-gelatin net-polymer microspheres

    NASA Astrophysics Data System (ADS)

    Zhou, Li; Xu, Junming; Song, Yimin; Gao, Yuanyuan; Chen, Xiguang

    2007-07-01

    The captopril/Chitosan-gelatin net-polymer microspheres (CTP/CGNPMs) were prepared using Chitosan (CTS) and gelatin (GT) by the methods of emulsification, cross-linked reagent alone or in combination and microcrystalline cellulose (MCC) added in the process of preparation of microspheres, which aimed to eliminate dose dumping and burst phenomenon of microspheres for the improvement of the therapeutic efficiency and the decrease of the side effects of captopril (CTP). The results indicated that CTP/CGNPMs had a spherical shape, smooth surface and integral structure inside but no adhesive phenomena in the preparation. The size distribution ranged from 220 μm to 280 μm. The CTP release test in vitro demonstrated that CTP/CGNPMs played the role of retarding the release of CTP compared with ordinary CTP tablets. The release behaviors of CGNPMS were influenced by preparation conditions such as experimental material ratio (EMR) and composition of cross linking reagents. Among these factors, the EMR (1/4), CLR (FA+SPP) and 0.75% microcrystalline cellulose (MCC) added to the microspheres constituted the optimal scheme for the preparation of CTP/CGNPMs. The ER, DL and SR of CTP/CGNPMs prepared according to the optimal scheme were 46.23±4.51%, 9.95±0.77% and 261±42%, respectively. The CTP/CGNPMs had the good characteristics of sustained release of drug and the process of emulsification and cross-linking were simple and stable. The CGNPMs are likely to be an ideal sustained release formulation for water-soluble drugs.

  18. Preparation and Determination of Drug-Polymer Interaction and In-vitro Release of Mefenamic Acid Microspheres Made of CelluloseAcetate Phthalate and/or Ethylcellulose Polymers

    PubMed Central

    Jelvehgari, Mitra; Hassanzadeh, Davoud; Kiafar, Farhad; Delf Loveym, Badir; Amiri, Sara

    2011-01-01

    The objective of this study was to formulate and evaluate the drug-polymer interaction of mefenamic acid (MA) using two polymers with different characteristics as ethylcellulose (EC) and/or cellulose acetate phthalate (CAP). Microspheres were prepared by the modified emulsion solvent evaporation (MESE). The effect of drug-polymer interaction was studied for each of microspheres. Important parameters in the evaluation of a microencapsulation technique are encapsulation efficiency, yield production, particle size, surface characteristics of microspheres, scanning electronic microscopy (SEM), powder X-ray diffraction analysis (XRD), and differential scanning calorimetry (DSC). The in-vitro release studies are performed in Tris buffer (pH 9) with Sodium lauryl sulfate (SLS). Microspheres containing CAP and EC showed 68-97% and 63-76% of entrapment efficiency, respectively. The thermogram X-ray and DSC showed stable character of MA in the microspheres and revealed an absence of drug polymer interaction. The prepared microspheres were spherical in shape and had a size range of 235-436 μm for CAP-microspheres and 358-442 μm for EC-microspheres. The results suggest that MA was successfully and efficiently encapsulated; the release rates of matrix microspheres are related to the type of polymer, only when polymers (EC and CAP combine with 1 : 1 ratio) were used to get prolonged drug release with reducing the polymers content in the microspheres. Data obtained from in-vitro release for microspheres and commercial capsule were fitted to various kinetic models and the high correlation was obtained in the peppas model. Mefenamic acid, Ethylcellulose, Cellulose acetate phthalate, Microparticles, Modified emulsion-solvent evaporation. PMID:24250377

  19. Preparation of chitosan/nano hydroxyapatite organic-inorganic hybrid microspheres for bone repair.

    PubMed

    Chen, Jingdi; Pan, Panpan; Zhang, Yujue; Zhong, Shengnan; Zhang, Qiqing

    2015-10-01

    In this work, we encapsulated icariin (ICA) into chitosan (CS)/nano hydroxyapatite (nHAP) composite microspheres to form organic-inorganic hybrid microspheres for drug delivery carrier. The composition and morphology of composite microspheres were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and differential scanning calorimetry- thermogravimetric analysis (DSC-TGA). Moreover, we further studied the performance of swelling properties, degradation properties and drug release behavior of the microspheres. ICA, the extract of traditional Chinese medicine-epimedium, was combined to study drug release properties of the microspheres. ICA loaded microspheres take on a sustained release behavior, which can be not only ascribed to electrostatic interaction between reactive negative hydroxyl (OH) of ICA and positive amine groups (NH₂) of CS, but also depended on the homogeneous dispersion of HAP nanoparticles inside CS organic matrix. In addition, the adhesion and morphology of osteoblasts were detected by inverted fluorescence microscopy. The biocompatibility of CS/nHAP/ICA microspheres was evaluated by the MTT cytotoxicity assay, Hoechst 33258 and PI fluorescence staining. These studies demonstrate that composite microspheres provide a suitable microenvironment for osteoblast attachment and proliferation. It can be speculated that the ICA loaded CS-based organic-inorganic hybrid microspheres might have potential applications in drug delivery systems.

  20. Efficient Pb(II) removal using sodium alginate-carboxymethyl cellulose gel beads: Preparation, characterization, and adsorption mechanism.

    PubMed

    Ren, Huixue; Gao, Zhimin; Wu, Daoji; Jiang, Jiahui; Sun, Youmin; Luo, Congwei

    2016-02-10

    Alginate-carboxymethyl cellulose (CMC) gel beads were prepared in this study using sodium alginate (SA) and sodium CMC through blending and cross-linking. The specific surface area and aperture of the prepared SA-CMC gel beads were tested. The SA-CMC structure was characterized and analyzed via infrared spectroscopy, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. Static adsorption experiment demonstrated that Pb(II) adsorption of SA-CMC exceeded 99% under the optimized conditions. In addition, experiments conducted under the same experimental conditions showed that the lead ion removal efficiency of SA-CMC was significantly higher than that of conventional adsorbents. The Pb(II) adsorption process of SA-CMC followed the Langmuir adsorption isotherm, and the dynamic adsorption model could be described through a pseudo-second-order rate equation. Pb(II) removal mechanisms of SA-CMC, including physical, chemical, and electrostatic adsorptions, were discussed based on microstructure analysis and adsorption kinetics. Chemical adsorption was the main adsorption method among these mechanisms.

  1. Polysaccharide-based aerogel microspheres for oral drug delivery.

    PubMed

    García-González, C A; Jin, M; Gerth, J; Alvarez-Lorenzo, C; Smirnova, I

    2015-03-06

    Polysaccharide-based aerogels in the form of microspheres were investigated as carriers of poorly water soluble drugs for oral administration. These bio-based carriers may combine the biocompatibility of polysaccharides and the enhanced drug loading capacity of dry aerogels. Aerogel microspheres from starch, pectin and alginate were loaded with ketoprofen (anti-inflammatory drug) and benzoic acid (used in the management of urea cycle disorders) via supercritical CO2-assisted adsorption. Amount of drug loaded depended on the aerogel matrix structure and composition and reached values up to 1.0×10(-3) and 1.7×10(-3) g/m(2) for ketoprofen and benzoic acid in starch microspheres. After impregnation, drugs were in the amorphous state in the aerogel microspheres. Release behavior was evaluated in different pH media (pH 1.2 and 6.8). Controlled drug release from pectin and alginate aerogel microspheres fitted Gallagher-Corrigan release model (R(2)>0.99 in both cases), with different relative contribution of erosion and diffusion mechanisms depending on the matrix composition. Release from starch aerogel microspheres was driven by dissolution, fitting the first-order kinetics due to the rigid starch aerogel structure, and showed different release rate constant (k1) depending on the drug (0.075 and 0.160 min(-1) for ketoprofen and benzoic acid, respectively). Overall, the results point out the possibilities of tuning drug loading and release by carefully choosing the polysaccharide used to prepare the aerogels.

  2. Preparation of uniform-sized exenatide-loaded PLGA microspheres as long-effective release system with high encapsulation efficiency and bio-stability.

    PubMed

    Qi, Feng; Wu, Jie; Fan, Qingze; He, Fan; Tian, Guifang; Yang, Tingyuan; Ma, Guanghui; Su, Zhiguo

    2013-12-01

    Exenatide-loaded poly(d,l-lactic-co-glycolic acid) (PLGA) microspheres hold great potential as a drug delivery system to treat type 2 diabetes mellitus (T2DM) because they can overcome the shortcoming of exenatide's short half-life and realize sustained efficacy. However, conventional preparation methods often lead to microspheres with a broad size distribution, which in turn would cause poor preparation repeatability, drug efficacy and so forth. In this study, we used Shirasu Porous Glass (SPG) premix membrane emulsification technique characterized with high trans-membrane flux and size controllability to prepare uniform-sized PLGA microspheres. By optimizing trans-membrane pressure and PVA concentration in external aqueous phase, uniform-sized PLGA microspheres with large size (around 20μm) were successfully obtained. To achieve high encapsulation efficiency (EE) and improve in vitro release behavior, we have carefully examined the process parameters. Our results show that using ultrasonication to form primary emulsion, microspheres with high EE were easily obtained, but the rate of in vitro release was very slow. Instead, high EE and appropriate in vitro release were achieved when homogenization with optimized time and speed were employed. Besides, we also systematically investigated the effect of formulations on loading efficiency (LE) as well as the relationship between the resultant size of the microspheres and pore size of the membrane. Finally, through RP-HPLC and CD spectra analysis, we have demonstrated that the bio-stability of exenatide in microspheres was preserved during the preparation process.

  3. Preparation, Characterization, and In Vivo Evaluation of Olanzapine Poly(D,L-lactide-co-glycolide) Microspheres

    PubMed Central

    D'Souza, Susan; Faraj, Jabar A.; Giovagnoli, Stefano; DeLuca, Patrick P.

    2013-01-01

    The aim of this study was to prepare injectable depot formulations of Olanzapine using four poly(D,L-lactide-co-glycolide) (PLGA) polymers of varying molecular weight and copolymer composition, and evaluate in vivo performance in rats. In vivo release profiles from the formulations were governed chiefly by polymer molecular weight and to a lesser extent, copolymer composition. Formulations A and B, manufactured using low molecular weight PLGA and administered at 10 mg/kg dose, released drug within 15 days. Formulation C, prepared from intermediate molecular weight PLGA and administered at 20 mg/kg dose, released drug in 30 days, while Formulation D, manufactured using a high molecular weight polymer and administered at 20 mg/kg dose, released drug in 45 days. A simulation of multiple dosing at 7- and 10-day intervals for Formulations A and B revealed that steady state was achieved within 7–21 days and 10–30 days, respectively. Similarly, simulations at 15-day intervals for Formulations C and D indicated that steady state levels were reached during days 15–45. Overall, steady state levels for 7-, 10-, or 15-day dosing ranged between 45 and 65 ng/mL for all the formulations, implying that Olanzapine PLGA microspheres can be tailored to treat patients with varying clinical needs. PMID:26555996

  4. Supercapacitive performance of hierarchical porous carbon microspheres prepared by simple one-pot method

    NASA Astrophysics Data System (ADS)

    Zhao, Qinglan; Wang, Xianyou; Wu, Chun; Liu, Jing; Wang, Hao; Gao, Jiao; Zhang, Youwei; Shu, Hongbo

    2014-05-01

    The hierarchical porous carbon microspheres (HPCMSs) using furfuryl alcohol as carbon resource have been prepared by a simple one-pot method. The HPCMSs are characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and nitrogen adsorption/desorption isotherm at 77 K, cyclic voltammetry (CV), galvanostatic charge/discharge tests, electrochemical impedance spectroscopy (EIS) and cycle life measurements in 6 M KOH. The results show that all the HPCMSs samples, which can be fabricated by adjusting the ratio of furfuryl alcohol/tetraethyl orthosilicate, possess three-dimensionally tailored pore structures with unique micro-, meso- and macroporous systems. Particularly, the HPCMS-2 prepared at the mole ratio of 2/1 (furfuryl alcohol/tetraethyl orthosilicate) shows the largest specific surface area of 709 m2 g-1, and the HPCMS-2 electrode owns specific capacitance as high as 221 F g-1 at the current density of 1 A g-1. The supercapacitor using HPCMS-2 as the active material shows high specific capacitance and excellent cycle stability, which exhibits a specific capacitance of 56 F g-1 at the charge/discharge current density of 0.5 A g-1. Furthermore, the HPCMS-2 supercapacitor delivers high energy densities of 6.1 Wh kg-1 at the power density of 5000 W kg-1, revealing a promising application in supercapacitors.

  5. Controllable preparation of nanoparticle-coated chitosan microspheres in a co-axial microfluidic device.

    PubMed

    Lan, Wenjie; Li, Shaowei; Xu, Jianhong; Luo, Guangsheng

    2011-02-21

    In this work, we describe a novel and simple microfluidic method for fabricating nanoparticle-coated chitosan microspheres. Uniform droplets of aqueous chitosan solution were dispersed into an oil phase containing partially hydrophilic nanoparticles via a co-axial microfluidic device. Recirculating flow in the continuous phase in the area between drops enhanced mixing and allowed the nanoparticles to coat the surface of the droplets as they passed through the channel. The chitosan droplets were then crosslinked with glutaraldehyde and nanoparticle-coated microspheres were obtained. SEM characterization shows that the microspheres are monodispersed with uniform nanoparticle distribution on the surface. The dispersity, size and composition of the microspheres could all easily be controlled by changing the microfluidic flow parameters and three different types of nanoparticles were successfully used to synthesize hybrid microspheres to demonstrate the method's versatility.

  6. Preparation and characterization of hollow glass microspheres coated by CoFe{sub 2}O{sub 4} nanoparticles using urea as precipitator via coprecipitation method

    SciTech Connect

    Pang Xiaofen; Fu Wuyou; Yang Haibin Zhu Hongyang; Xu Jing; Li Xiang; Zou Guangtian

    2009-02-04

    The composite of hollow glass microspheres coated by CoFe{sub 2}O{sub 4} nanoparticles has been successfully prepared using urea as precipitator via coprecipitation method. The resultant composites were characterized by X-ray diffraction, field emission scanning electron microscope and vibrating sample magnetometer. The results showed that the slow decomposition of urea could be beneficial to form uniform and entire cobalt ferrite coating layer on the surface of hollow glass microspheres. The smoothest morphology was obtained for the sample prepared from 0.7 M urea, while the sample prepared from 1.0 M urea had the thickest shell. This indicated that there was a competition between the morphology and thickness of the coated microspheres. A possible formation mechanism of hollow glass microspheres coated with cobalt ferrite was proposed. The magnetic properties of the samples were also investigated.

  7. Sophoridine-loaded PLGA microspheres for lung targeting: preparation, in vitro, and in vivo evaluation.

    PubMed

    Wang, Wenping; Cai, Yaqin; Zhang, Guangxing; Liu, Yanhua; Sui, Hong; Park, Kinam; Wang, Hong

    2016-11-01

    Lung-targeting sophoridine-loaded poly(lactide-co-glycolide) (PLGA) microspheres were constructed by a simple oil-in-oil emulsion-solvent evaporation method. The obtained microspheres were systematically studied on their morphology, size distribution, drug loading, encapsulation efficiency, in vitro release profile, and biodistribution in rats. The drug-loaded microparticles showed as tiny spheres under SEM and had an average size of 17 μm with 90% of the microspheres ranging from 12 to 24 μm. The drug loading and encapsulation efficiency were 65% and 6.5%, respectively. The in vitro drug release behavior of microspheres exhibited an initial burst of 16.6% at 4 h and a sustained-release period of 14 days. Drug concentration in lung tissue of rats was 220.10 μg/g for microspheres and 6.77 μg/g for solution after intraveneous injection for 30 min, respectively. And the microsphere formulation showed a significantly higher drug level in lung tissue than in other major organs and blood samples for 12 days. These results demonstrated that the obtained PLGA microspheres could potentially improve the treatment efficacy of sophoridine against lung cancer.

  8. Preparation and evaluation of the in vitro drug release properties and mucoadhesion of novel microspheres of hyaluronic acid and chitosan.

    PubMed

    Lim, S T; Martin, G P; Berry, D J; Brown, M B

    2000-05-15

    Rapid mucociliary clearance of intranasally administered drugs is often a key factor in determining the bioavailability of such therapeutic agents. The use of mucoadhesive microparticles provide a potential strategy for improving retention of drugs within the nasal cavity, and thereby improve the resultant pharmacokinetic profile. This study describes the comparison of a number of novel, potentially mucoadhesive microspheres, prepared by solvent evaporation, composed of hyaluronic acid (HA), chitosan glutamate (CH) and a combination of the two with microcapsules of HA and gelatin prepared by complex coacervation. The microspheres had a mean particle size of 19.91+/-1.57 microm (HA), 28.60+/-1.34 microm (HA/CH), 29.47+/-3.58 microm (CH). The incorporation of a model drug, gentamicin sulphate (%) was 46.90+/-0.53 (HA), 28.04+/-1.21 (HA/CH) and 13.32+/-1.04 (CH). The in vitro release profiles of microsphere formulations prepared by solvent evaporation were determined. The release of gentamicin from HA and HA/CH was 50% longer than CH and was best modelled as a release from a matrix. The degree of mucoadhesion of each formulation was investigated by determining the mucociliary transport rate (MTR) of the microparticles across an isolated frog palate. Acacia/gelatin microcapsules were used as a positive control. The rank order of mucoadhesion for the microspheres and the microparticles was HA=HA/CH>CH>HA/gelatin>CHins. The entrapment of gentamicin did not affect the mucoadhesive properties (P>0.05, Mann--Whitney U-test). The combination of HA with chitosan may afford additional advantages in combining the mucoadhesive potential of HA with the penetration enhancing effect of chitosan.

  9. Polymeric microspheres

    DOEpatents

    Walt, David R.; Mandal, Tarun K.; Fleming, Michael S.

    2004-04-13

    The invention features core-shell microsphere compositions, hollow polymeric microspheres, and methods for making the microspheres. The microspheres are characterized as having a polymeric shell with consistent shell thickness.

  10. Preparation and cytotoxicity of N,N,N-trimethyl chitosan/alginate beads containing gold nanoparticles.

    PubMed

    Martins, Alessandro F; Facchi, Suelen P; Monteiro, Johny P; Nocchi, Samara R; Silva, Cleiser T P; Nakamura, Celso V; Girotto, Emerson M; Rubira, Adley F; Muniz, Edvani C

    2015-01-01

    Polyelectrolyte complex beads based on N,N,N-trimethyl chitosan (TMC) and sodium alginate (ALG) were obtained. This biomaterial was characterised by FTIR, TGA/DTG, DSC and SEM analysis. The good properties of polyelectrolyte complex hydrogel beads were associated, for the first time, with gold nanoparticles (AuNPs). Through a straightforward methodology, AuNPs were encapsulated into the beads. The in vitro cytotoxicity assays on the Caco-2 colon cancer cells and healthy VERO cells showed that the beads presented good biocompatibility on both cell lines, whereas the beads loaded with gold nanoparticles (beads/AuNPs) was slightly cytotoxic on the Caco-2 and VERO cells.

  11. Nanostructured gold hollow microspheres prepared on dissolvable ceramic hollow sphere templates.

    PubMed

    Chah, S; Fendler, J H; Yi, J

    2002-06-01

    Fifty and one-hundred micrometer diameter nanostructured gold hollow microspheres (GHSs), in >98% purity, have been prepared by using ceramic hollow spheres, CHSs, as templates. Tennanometer diameter gold nanoparticles were covalently linked to the thiol moiety of (3-mercaptopropyl)trimethoxysilane, which had been self-assembled onto the CHSs. Greater structural strength was obtained by the generation of additional gold nanoparticles, in situ on the gold nanoparticle coated CHSs (by immersing the gold nanoparticle coated CHSs into an aqueous mixture of hydroxylamine and gold chloride). GHSs were obtained by dissolving the CHSs templates. The sizes, shapes, surface areas (185.3 m2/g for CHSs and 182.9 m2/g for GHSs), pore diameters (7.7 nm for CHSs and 7.8 nm for GHSs), and pore volumes (0.41 cm3/g for CHSs and 0.36 cm3/g for GHSs) of GHSs were quite similar to their CHSs counterparts. Significantly, GHSs showed surface plasmon bands whose maximum (644 nm) shifted from that observed for the parent 10-nm gold nanoparticles (522 nm).

  12. Preparation of SnO2-coated Ni microsphere composites with controlled microwave absorption properties

    NASA Astrophysics Data System (ADS)

    Zhao, Biao; Shao, Gang; Fan, Bingbing; Guo, Wenhui; Chen, Yongqiang; Zhang, Rui

    2015-03-01

    In this work, the core-shell structured Ni/SnO2 composites have been successfully synthesized by a hydrothermal deposition method (HDM). The crystal structure, morphology and electromagnetic (EM) properties of Ni/SnO2 composites were investigated. The effects of SnO32- and urea contents on the morphologies of final Ni/SnO2 samples were also considered. The microwave absorption properties of Ni microspheres are remarkably enhanced after coating whit SnO2 nanaoshells. Moreover, the microwave absorption properties of core-shell structured Ni/SnO2 composites can be tailored by tuning SnO2 contents. The results show that the Ni/SnO2 composites prepared at 0.017 M SnO32- exhibit outstanding microwave absorption properties with a minimum reflection loss of -42.8 dB at 9.8 GHz with the corresponding thickness of 3.0 mm. The reflection loss below -10 dB can be obtained in a wide range of 5.8-18.0 GHz by adjusting the absorber thicknesses from 1.5 mm to 4.5 mm. The excellent microwave absorption properties are attributed to high magnetic loss, dielectric loss, multi-resonance and interfacial polarization of the core-shelled Ni/SnO2 composites.

  13. Preparation, Characterization, In Vitro Release and Degradation of Cathelicidin-BF-30-PLGA Microspheres

    PubMed Central

    Li, Hongli; Yuan, Mingwei; Yuan, Minglong

    2014-01-01

    Cathelicidin-BF-30 (BF-30), a water-soluble peptide isolated from the snake venom of Bungarus fasciatus containing 30 amino acid residues, was incorporated in poly(D,L-lactide-co-glycolide) (PLGA) 75∶25 microspheres (MS) prepared by a water in oil in water W/O/W emulsification solvent extraction method. The aim of this work was to investigate the stability of BF-30 after encapsulation. D-trehalose was used as an excipient to stabilize the peptide. The MS obtained were mostly under 2 µm in size and the encapsulation efficiency was 88.50±1.29%. The secondary structure of the peptide released in vitro was determined to be nearly the same as the native peptide using Circular Dichroism (CD). The ability of BF-30 to inhibit the growth of Escherichia coli was also maintained. The cellular relative growth and hemolysis rates were 92.16±3.55% and 3.52±0.45% respectively. PMID:24963652

  14. Facile preparation of superparamagnetic surface-imprinted microspheres using amino acid as template for specific capture of thymopentin

    NASA Astrophysics Data System (ADS)

    Guo, Longxia; Hu, Xiaoling; Guan, Ping; Du, Chunbao; Wang, Dan; Song, Dongmen; Gao, Xumian; Song, Renyuan

    2015-12-01

    Novel superparamagnetic surface-imprinted microspheres (SIMs) with molecularly imprinted shell layer were controllably synthesized via fragment imprinting and surface imprinting technique. The SIMs-Arg and SIMs-Lys microspheres were prepared by using L-arginine (L-Arg) and L-lysine (L-Lys) as pseudo-template molecule for specific rebinding to thymopentin (TP5), respectively. The characterization results revealed that both SIMs-Arg and SIMs-Lys were successfully prepared and possessed a high magnetic sensitivity. The rebinding-isotherm analyses of SIMs-Arg and SIMs-Lys showed that the Langmuir isotherm model was well fitted to the equilibrium data, indicating that only one kind of rebinding site was present in SIMs-Arg and SIMs-Lys. Besides, the kinetic properties of SIMs-Arg and SIMs-Lys both were well described by the pseudo-second-order kinetics model, which indicated that a chemical process may be the rate-limiting step in the rebinding process. Moreover, the magnetic imprinted microspheres were found to have a higher specificity for TP5 than that for immunostimulating peptide human (IPH). What is more, SIMs-Arg and SIMs-Lys were successfully applied for TP5 determination in urine. According to the maximum adsorption capacity, the imprinting factor and real sample experiment, it was noted that SIMs-Arg had better specific adsorption property for TP5 than SIMs-Lys.

  15. Preparation of monodispersed chitosan microspheres and in situ encapsulation of BSA in a co-axial microfluidic device.

    PubMed

    Xu, J H; Li, S W; Tostado, C; Lan, W J; Luo, G S

    2009-02-01

    This work describes a novel microfluidic method to prepare monodispersed chitosan microspheres by using the solvent extraction method. Our strategy is that a chitosan/acetic acid aqueous solution is emulsified in an organic phase containing the extractant by using the co-flowing shear method in a co-axial microfluidic device. The formed droplets are in situ solidified within a synthesizing channel by the extraction of acetic acid from the chitosan aqueous droplets to the organic solution. Based on this approach, the size of chitosan microspheres can be successfully controlled from 100 mum to 700 mum in diameter with a variation of less than 4%. Furthermore, high loading efficiency (>95%) of Bovine serum albumin (BSA) can be in situ encapsulated. The present method has the advantages of actively controlling the droplet diameter, narrow size distribution, good sphericity, and having a simple and low cost process, with a high throughput. This approach for the preparation of chitosan microspheres will provide many potential applications for pharmaceutical area.

  16. Reactive carbon microspheres prepared by surface-grafting 4-(chloromethyl)phenyltrimethoxysilane for preparing molecularly imprinted polymer

    NASA Astrophysics Data System (ADS)

    Liu, Weifeng; Zhao, Huijun; Yang, Yongzhen; Liu, Xuguang; Xu, Bingshe

    2013-07-01

    Carbon microspheres (CMSs) were oxidized by a mixture of concentrated sulfuric and nitric acids, and modified by 4-(chloromethyl)phenyltrimethoxysilane to give reactive surface. Then, by adopting the surface molecular imprinting technique, dibenzothiophene (DBT) molecule-imprinted material MIP-DBT/CMSs was prepared with methacrylic acid as functional monomer and ethylene glycol dimethacrylate as crosslinking agent. The binding character of MIP-DBT/CMSs toward DBT was investigated with static method by gas chromatography, using fluorene and biphenyl as the reference substances which are similar to DBT in chemical structure to a certain extent. The effects of reaction time, temperature, and coupling agent concentration during silanization were investigated. The results show that the optimized conditions of silanization were 0.3 g oxidized-CMSs, 5% of CMTMS, 80 °C and 4 h. On the basis of silanized-CMSs, MIP-DBT/CMSs was synthesized. The adsorption results show that MIP-DBT/CMSs possessed strong adsorption ability for DBT. The maximal adsorption amount reached up 88.83 mg/g, in comparison with 44.51 mg/g of the non-imprinted polymer. In addition, MIP-DBT/CMSs exhibited a good selective adsorption capacity for DBT than fluorene (19.86 mg/g) and biphenyl (15.33 mg/g). The adsorption behavior followed the pseudo second order kinetic model. And the Freundlich isotherm was found to describe well the equilibrium adsorption data.

  17. [Impact of formulation and process parameters on the properties of chitosan-based microspheres prepared by external ionic gelation].

    PubMed

    Kubánková, Romana; Vysloužil, Jakub; Kejdušová, Martina; Vetchý, David; Dvořáčková, Kateřina

    2014-06-01

    The aim of this experimental study was to optimize a preparation of microspheres from high viscosity chitosan by external ion gelation and to evaluate selected aspects of their preparation. For drug-free microparticles, the concentration of chitosan dispersions was chosen as a formulation variable; the position of instrument for a dispersion extrusion (horizontal vs. vertical) was evaluated as a process variable. On the basis of sphericity and equivalent diameter results, three different concentrations of chitosan dispersions were used for 5-aminosalicylic acid (5-ASA) encapsulation with the extrusion instrument in horizontal position, which was considered as the optimal. In consequent drug-loaded microparticle preparation, the influence of the concentration of chitosan dispersions and composition of hardening solution (10% sodium tripolyphosphate (TPP) vs. 10% TPP containing drug) was evaluated. In prepared 5-ASA microspheres it was found that the equivalent diameter increased with increasing chitosan concentration. In the case of sphericity, significant differences were not found. Samples prepared with the drug in both chitosan dispersion and hardening solution had a higher drug content, a smaller equivalent diameter and they showed a faster in vitro drug release in comparison with the samples prepared with the drug in chitosan dispersion only.

  18. Recycling of chemicals from alkaline waste generated during preparation of UO 3 microspheres by sol-gel process

    NASA Astrophysics Data System (ADS)

    Kumar, Ashok; Vittal Rao, T. V.; Mukerjee, S. K.; Vaidya, V. N.

    2006-05-01

    Internal gelation process, one of the sol-gel processes for nuclear fuel fabrication, offers many advantages over conventional powder pellet route. However, one of the limitation of the process is generation of large volume of alkaline liquid waste containing hexamethylenetetramine, urea, ammonium nitrate, ammonium hydroxide etc. Presence of ammonium nitrate with hexamethylenetetramine and urea presents a fire hazard which prevents direct disposal of the waste as well as its recycle by evaporation. The paper describes the studies carried out to suitably process the waste. Nitrate was removed from the waste by passing through Dowex 1 × 4 anion exchange resin in OH - form. 1.0 M NaOH was used to regenerate the resin. The nitrate-free waste was further treated to recover and recycle hexamethylenetetramine, urea and ammonium hydroxide for preparation of UO 3 microspheres. The quality of the microspheres obtained was satisfactory. An optimized flow sheet for processing of the waste solution has been suggested.

  19. Preparation of hollow magnetite microspheres and their applications as drugs carriers

    PubMed Central

    2012-01-01

    Hollow magnetite microspheres have been synthesized by a simple process through a template-free hydrothermal approach. Hollow microspheres were surface modified by coating with a silica nanolayer. Pristine and modified hollow microparticles were characterized by field-emission electron microscopy, transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, FT-IR and Raman spectroscopy, and VSM magnetometry. The potential application of the modified hollow magnetite microspheres as a drug carrier was evaluated by using Rhodamine B and methotrexate as model drugs. The loading and release kinetics of both molecules showed a clear pH and temperature dependent profile. Graphical abstract Hollow magnetite microspheres have been synthesized. Load-release experiments with Rhodamine-B as a model drug and with Methotrexate (chemotherapy drug used in treating certain types of cancer) demonstrated the potential applications of these nanostructures in biomedical applications. PMID:22490731

  20. [Preparation of porous silica microspheres with high porosity using base-dissolving method].

    PubMed

    Zhao, Rui; Li, Xinhui; Liu, Guoquan

    2005-11-01

    A novel method was proposed and studied for the preparation of porous silica with high porosity using base-dissolving technology. The relationships between the removal of silica and the base concentration, the reaction temperature as well as the reaction time were evaluated. The amount of silica removed from silica spheres was increased and silica-dissolving rate was also accelerated along with the increase of NaOH concentration. This was due to the damage of some inner walls of the porous silica and the dissolution of small fragments into the base solution. The amount of silica removed was in direct proportion to the reaction temperature and reaction time. Moreover, the specific pore volumes were linearly increased along with the increase of the amount of silica removed. The treated silica particles remained as homogeneous spheres and the changes of the particle diameter were not observed. Under the optimized conditions with the NaOH solution of 1.25 mol/L, the reaction temperature of 25 degrees C and the reaction time of 3.0 h, the original silica spheres with the diameter of 4 - 5 microm, the pore size of 8 nm and the specific pore volume (V(p)) of 1.4 cm3/g were modified to the high-porosity silica with the diameter of 4 - 5 microm, the pore size of 14 nm and the V(p) of 3.2 cm3/g. The porosity of the silica microspheres was changed from 75% to 88%. This high-porosity silica was suitable for the preparation of high performance gel filtration packings.

  1. Preparation of hollow core/shell microspheres of hematite and its adsorption ability for samarium.

    PubMed

    Yu, Sheng-Hui; Yao, Qi-Zhi; Zhou, Gen-Tao; Fu, Sheng-Quan

    2014-07-09

    Hollow core/shell hematite microspheres with diameter of ca. 1-2 μm have been successfully achieved by calcining the precursor composite microspheres of pyrite and polyvinylpyrrolidone (PVP) in air. The synthesized products were characterized by a wide range of techniques including powder X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), high-resolution TEM (HRTEM), thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC), and Brunauer-Emmett-Teller (BET) gas sorptometry. Temperature- and time-dependent experiments unveil that the precursor pyrite-PVP composite microspheres finally transform into hollow core/shell hematite microspheres in air through a multistep process including the oxidation and sulfation of pyrite, combustion of PVP occluded in the precursor, desulfation, aggregation, and fusion of nanosized hematite as well as mass transportation from the interior to the exterior of the microspheres. The formation of the hollow core/shell microspheres dominantly depends on the calcination temperature under current experimental conditions, and the aggregation of hematite nanocrystals and the core shrinking during the oxidation of pyrite are responsible for the formation of the hollow structures. Moreover, the adsorption ability of the hematite for Sm(III) was also tested. The results exhibit that the hematite microspheres have good adsorption activity for trivalent samarium, and that its adsorption capacity strongly depends on the pH of the solution, and the maximum adsorption capacity for Sm(III) is 14.48 mg/g at neutral pH. As samarium is a typical member of the lanthanide series, our results suggest that the hollow hematite microspheres have potential application in removal of rare earth elements (REEs) entering the water environment.

  2. Preparation of monodisperse microspheres from the Laplace pressure induced droplet formation in micromolds

    NASA Astrophysics Data System (ADS)

    Choi, Chang-Hyung; Kim, Jongmin; Kang, Sung-Min; Lee, Jinkee; Lee, Chang-Soo

    2013-03-01

    Monodisperse microspheres play critical roles in many applications such as micro-electromechanical systems (MEMS), chemical release systems, optical materials and various biological applications. Although microfluidic systems have been developed for producing monodisperse microspheres, it still definitely requires pressure driven flow for continuous fluid injection as well as use of surfactant to achieve their uniformity. Here, we present a novel molding method that generates monodisperse microspheres through surface-tension-induced flow. Two immiscible fluids that consist of photocurable monomer and hydrophobic oil are sequentially applied onto the mold. The mold geometry results in Laplace pressure induced droplet formation, and these droplets formed are individually localized into each micromold. Photopolymerization of the droplets allow for the formation of polymer microspheres with narrow size distribution (CV =1.9%). We obtain the microspheres with diameter ranging from 20 to 300 μm by modulating mold dimensions. We provide a synthesis method to produce microspheres in micromolds for various reaction schemes: UV-polymerization, sol-gel reactions and colloidal assemblies.

  3. Preparation and drug release properties of norisoboldine-loaded chitosan microspheres.

    PubMed

    He, Miao; Wang, Haiyan; Dou, Wei; Chou, Guixin; Wei, Xiaohui; Wang, Zhengtao

    2016-10-01

    This study aimed to develop injectable norisoboldine (NOR) chitosan microspheres formulated through the emulsion cross-linking method. The formulation was optimized using response surface methodology (RSM) with a three-level, three-factor Box-Behnken design (BBD). The morphology, size, physicochemical characterization and in vitro release behavior of the optimized formulation were evaluated. Scanning electron micrographs (SEM) indicated that the microspheres were spherical with a smooth surface. The encapsulation efficiency and drug loading content of the microspheres were 38.89%±1.72% and 4.25%±0.15%, respectively, with an average size of 105μm. Fourier-transform infrared (FT-IR) spectroscopy, differential scanning calorimetry (DSC) and X-ray diffraction (XRD) revealed the absence of a drug-polymer interaction and the amorphous nature of an entrapped drug. Analysis results of drug release in vitro show the burst release of the microsphere in 2h and a slow progression afterward. In vivo studies using Sprague-Dawley rats revealed that the NOR-loaded chitosan microspheres were biocompatible. This study suggests that the BBD with desired formulation could provide a suitable drug delivery system of chitosan microspheres.

  4. Novel zinc alginate hydrogels prepared by internal setting method with intrinsic antibacterial activity.

    PubMed

    Straccia, Maria Cristina; d'Ayala, Giovanna Gomez; Romano, Ida; Laurienzo, Paola

    2015-07-10

    In this paper, a controlled gelation of alginate was performed for the first time using ZnCO3 and GDL. Uniform and transparent gels were obtained and investigated as potential wound dressings. Homogeneity, water content, swelling capability, water evaporation rate, stability in normal saline solution, mechanical properties and antibacterial activity were assessed as a function of zinc concentration. Gelation rate increased at increasing zinc content, while a decrease in water uptake and an improvement of stability were found. Release of zinc in physiological environments showed that concentration of zinc released in solution lies below the cytotoxicity level. Hydrogels showed antimicrobial activity against Escherichia coli. The hydrogel with highest zinc content was stabilized with calcium by immersion in a calcium chloride solution. The resulting hydrogel preserved homogeneity and antibacterial activity. Furthermore, it showed even an improvement of stability and mechanical properties, which makes it suitable as long-lasting wound dressing.

  5. Preparation and evaluation of gastroretentive floating pellets of metronidazole using Na-alginate and hydroxyl propyl methyl cellulose polymers.

    PubMed

    Biswas, S K; Paul, S; Chowdhury, A; Das, J

    2012-03-15

    Gastroretentive floating pellets of metronidazole were formulated to prolong the gastric residence time in order to obtain controlled release characteristics of the drug. Nine formulations of metronidazole floating pellets such as AX, BX, CX, AY, BY, CY, AZ, BZ and CZ were prepared by extrusion method using different quantities of hydroxyl propyl methyl cellulose (HPMC) polymers such as methocel K4M premium and methocel K100LV premium in the ratio of 2:1, 1:2 and 1.5:1.5 while the amount of Na-alginate used in the formulations was 3.50, 5.25 and 7.0 g, respectively. The in vitro dissolution studies were carried out in 900 mL of phosphate buffer (pH 1.2) at 37 +/- 0.5 degrees C and 50 rpm for 6 h using USP XXIV paddle method and the content of drug release was done by UV spectrophotometer at 277 nm. It was found that the percent release of metronidazole from different formulations was different with passing of time. The drug release profile of the formulation (AX) having Na-alginate 3.50 g methocel K4M premium and methocel K100LV premium in the ratio of 2:1 showed best fit to Higuchi release kinetics with R2 value of 0.994. Finally, it might be concluded that the polymers had significant effect on drug release kinetics of metronidazole from floating pellets. The selection and use of suitable polymers in appropriate ratio might be very important in designing floating pellets and using the capabilities of these polymers, suitable floating pellets of metronidazole with desirable release rate could be formulated. Thus, in vivo research studies by the future researchers will confirm the appropriateness of these formulated metronidazole floating pellets.

  6. Preparation and characterization of succinic acid deamidated wheat gluten microspheres for encapsulation of fish oil.

    PubMed

    Liao, Lan; Luo, Yangchao; Zhao, Mouming; Wang, Qin

    2012-04-01

    Succinic acid deamidated wheat gluten (SDWG) microspheres for encapsulation of fish oil (FO) via O/W/O double-emulsion followed by heat-polymerization of emulsified SDWG was reported. Different SWDG concentrations (16.8-67.2 mg/ml) and FO/SDWG ratios (1:3-4:3, w/w) were studied. To optimize the process, particle size and Zeta potential of SDWG-FO emulsion and encapsulation efficiency (EE) of FO were analyzed. The most efficient condition was obtained at 50.4 mg/ml for SDWG and 3:3 (w/w) for FO/SDWG ratio, with an EE of 81.8%. In this condition, confocal microscopy showed FO well encapsulated in SDWG microspheres. Scanning electron microscope (SEM) showed sunken pores and fractures inside microspheres after FO was extracted, confirming the presence of FO in microspheres. FTIR and electrophoresis showed during microspheres formation dramatically elevated SWDG aggregation resulted in intermolecular-crosslinking and enhanced interactions (hydrogen bonds and hydrophobic interactions) between SDWG and FO. In the evaluations of in vitro experiments in simulated gastric fluid and oxidation stability during storage, results indicated that SDWG matrix protected it from both oxygen and gastric fluid, resulting in improved storage stability and release property. Therefore, it is foreseen that SDWG can be used to encapsulate FO or other sensitive nutraceuticals in the applications of supplementation and functional foods.

  7. Modified release and antioxidant stable Lagenaria siceraria extract microspheres using co-precipitated starch.

    PubMed

    Kulkarni, Sameer D; Sinha, Barij N; Kumar, K Jayaram

    2014-05-01

    Ca-alginate hydrogel beads of Lagenaria siceraria (LS) fruit extract using co-precipitates of LS seed starch and colloidal silicon dioxide (SSD) as filler was studied. Effect of different concentrations of SSD on the encapsulation efficiency, size of microspheres, moisture content and antioxidant potential of the microspheres comprising extract was determined. The chemical composition of ethanolic extract was analysed by LC-MS. The prepared microspheres were characterized by SEM, FTIR and XRD. The incorporation of filler in hydrogel beads modified the micromeritic properties and release profile of LS fruit extract. It is observed that fillers have improved the stability of antioxidant potential of the extract. The application of this technology would improve the stability of LS fruit extract in pharmaceutical and food products.

  8. Monodisperse α-Fe2O3 Mesoporous Microspheres: One-Step NaCl-Assisted Microwave-Solvothermal Preparation, Size Control and Photocatalytic Property

    NASA Astrophysics Data System (ADS)

    Cao, Shao-Wen; Zhu, Ying-Jie

    2011-12-01

    A simple one-step NaCl-assisted microwave-solvothermal method has been developed for the preparation of monodisperse α-Fe2O3 mesoporous microspheres. In this approach, Fe(NO3)3 · 9H2O is used as the iron source, and polyvinylpyrrolidone (PVP) acts as a surfactant in the presence of NaCl in mixed solvents of H2O and ethanol. Under the present experimental conditions, monodisperse α-Fe2O3 mesoporous microspheres can form via oriented attachment of α-Fe2O3 nanocrystals. One of the advantages of this method is that the size of α-Fe2O3 mesoporous microspheres can be adjusted in the range from ca. 170 to ca. 260 nm by changing the experimental parameters. High photocatalytic activities in the degradation of salicylic acid are observed for α-Fe2O3 mesoporous microspheres with different specific surface areas.

  9. Preparation of polystyrene/SiO2 microsphere via Pickering emulsion polymerization: Synergistic effect of SiO2 concentrations and initiator sorts

    NASA Astrophysics Data System (ADS)

    Zhou, Haiou; Shi, Tiejun; Zhou, Xun

    2013-02-01

    In this paper, polystyrene (PS)/SiO2 microspheres were successfully prepared via Pickering emulsion polymerization stabilized solely by ethacryloxypropyltrimethoxysilane (MPTMS) modified SiO2 nanoparticles. The formation mechanisms of PS/SiO2 microspheres with different morphology were investigated under various Pickering emulsion polymerization conditions. The results showed that SiO2 concentrations and initiator sorts would synergistically impact on the morphology of products corresponding to distinct formation mechanisms. When SiO2 concentrations was low and water-solute initiator potassium persulfate (KPS) was used, aqueous nucleation was dominant, which was deduced to the formation of dispersive microspheres sparsely anchored by SiO2 particles. When SiO2 concentrations was increased and oil-solute initiator azobisisobutyronitrile (AIBN) was applied, nucleation in oil phase prevailed which lead to the formation of microspheres densely packed by SiO2 particles.

  10. Monodisperse α-Fe2O3 Mesoporous Microspheres: One-Step NaCl-Assisted Microwave-Solvothermal Preparation, Size Control and Photocatalytic Property.

    PubMed

    Cao, Shao-Wen; Zhu, Ying-Jie

    2010-08-18

    A simple one-step NaCl-assisted microwave-solvothermal method has been developed for the preparation of monodisperse α-Fe2O3 mesoporous microspheres. In this approach, Fe(NO3)3 · 9H2O is used as the iron source, and polyvinylpyrrolidone (PVP) acts as a surfactant in the presence of NaCl in mixed solvents of H2O and ethanol. Under the present experimental conditions, monodisperse α-Fe2O3 mesoporous microspheres can form via oriented attachment of α-Fe2O3 nanocrystals. One of the advantages of this method is that the size of α-Fe2O3 mesoporous microspheres can be adjusted in the range from ca. 170 to ca. 260 nm by changing the experimental parameters. High photocatalytic activities in the degradation of salicylic acid are observed for α-Fe2O3 mesoporous microspheres with different specific surface areas.

  11. The preparation of core/shell structured microsphere of multi first-line anti-tuberculosis drugs and evaluation of biological safety

    PubMed Central

    Zeng, Hao; Pang, Xiaoyang; Wang, Shuo; Xu, Zhengquan; Peng, Wei; Zhang, Penghui; Zhang, Yupeng; Liu, Zheng; Luo, Chengke; Wang, Xiyang; Nie, Hemin

    2015-01-01

    To introduce a modified method, namely coaxial electrohydrodynamic atomization for the fabrication of distinct core/shell structured microspheres of four first-line ant-tuberculosis drugs with different characteristics in hydrophilic properties in one single step. In group B, we prepared microspheres in which the core and the shell contain hydrophobic and hydrophilic drugs, respectively. In contrast, in group C, the opposite is prepared. The detection of encapsulation efficiency and in vitro release test were performed to confirm the feasibility of the drug-loaded core/shell structured microspheres. Moreover, cell culture experiments and animal experiments have been carried out to evaluate the biological safety of different microspheres in cell growth, cell viability, osteogenesis and migration of BMSCs in vitro and the bone fusion in a bone deficits model in SD rat. Meanwhile, the distribution of drugs and liver and kidney toxicity were monitored. The release patterns of the two groups are significantly different. The release of drugs from Group B microspheres is rather sequential, whereas group C microspheres release drugs in a parallel (co-release) manner. And various concentrations of carrier materials produces core/shell structured microspheres with different appearance. Moreover, the biological safety of core/shell structured microspheres was testified to be satisfactory. These findings present the advantages and possible application of this kind of multi-drug release system in treating skeletal tuberculosis. Moreover, the characteristic sequential release of multi-drugs can be controlled and adjusted based on treatment need and used in treating other disorders. PMID:26309493

  12. Process for preparing metal-carbide-containing microspheres from metal-loaded resin beads

    DOEpatents

    Beatty, Ronald L.

    1976-01-01

    An improved method for treating metal-loaded resin microspheres is described which comprises heating a metal-loaded resin charge in an inert atmosphere at a pre-carbide-forming temperature under such conditions as to produce a microsphere composition having sufficient carbon as to create a substantially continuous carbon matrix and a metal-carbide or an oxide-carbide mixture as a dispersed phase(s) during carbide-forming conditions, and then heating the thus treated charge to a carbide-forming temperature.

  13. Preparation and evaluation of a novel gastric floating alginate/poloxamer inner-porous beads using foam solution.

    PubMed

    Yao, Huimin; Yao, Huijuan; Zhu, Junyi; Yu, Junlin; Zhang, Lifan

    2012-01-17

    In the present study, a simple and rapid method was developed to prepare a novel kind of inner-porous floating beads. The beads were prepared by dripping the foam solution into CaCl(2) solution using disposable syringe needle, where the foam solution consisting numerous of microbubbles with poloxamer 188 as foaming agents, alginate as foaming stablizer. Foamability and foam stability of different polymer ratios were evaluated. The SEM cross-section pictures of the beads showed that the beads were inner-porous and composed of bubbles with very thin wall bubbles stacked together. The visual observation result and the resultant-weight method confirmed that the floating beads showed good buoyancy, most beads could float in the stomach for more than 6 h. The floating beads release behavior in vitro showed that drug release from the beads in a sustained-release fashion for 10 h. Gamma scintigraphic images and pharmacokinetic studies in vivo showed that the beads can retained in the stomach for over 6 h and can improve the bioavailability of drug with narrow absorption window.

  14. The quest for targeted delivery in colon cancer: mucoadhesive valdecoxib microspheres

    PubMed Central

    Thakral, Naveen K; Ray, Alok R; Bar-Shalom, Daniel; Eriksson, André Huss; Majumdar, Dipak K

    2011-01-01

    The aim of the present study was to prepare valdecoxib, a cyclo-oxygenase-2 enzyme inhibitor, as a loaded multiparticulate system to achieve site-specific drug delivery to colorectal tumors. Film coating was done with the pH-sensitive polymer Eudragit S100 and sodium alginate was used as mucoadhesive polymer in the core. The microspheres were characterized by X-ray diffraction, differential scanning calorimetry, and Fourier transform infrared spectroscopy and were evaluated for particle size, drug load, in vitro drug release, release kinetics, accelerated stability, and extent of mucoadhesion. The coated microspheres released the drug at pH 7.4, the putative parameter for colonic delivery. When applied to the mucosal surface of freshly excised goat colon, microspheres pretreated with phosphate buffer pH 7.4 for 30 minutes showed mucoadhesion. To ascertain the effect of valdecoxib on the viability of Caco-2 cells, the 3-(4,5-dimethylthiazol-2yl) 2,5-diphenyltetrazolium bromide) test was conducted using both valdecoxib and coated microspheres. In both cases, the percentage of dehydrogenase activity indicated a lack of toxicity against Caco-2 cells in the tested concentration range. Drug transport studies of the drug as well as the coated microspheres in buffers of pH 6 and 7.4 across Caco-2 cell monolayers were conducted. The microspheres were found to exhibit slower and delayed drug release and lower intracellular concentration of valdecoxib. PMID:21720517

  15. Preparation and in vitro evaluation of propylthiouracil microspheres made of Eudragit RL 100 and cellulose acetate butyrate polymers using the emulsion-solvent evaporation method.

    PubMed

    Obeidat, W M; Price, J C

    2005-05-01

    The objectives of this investigation are to evaluate the encapsulation efficiency of the anti-thyroid agent 6-n-propyl-2-thiouracil using two polymers of different characteristics (cellulose acetate butyrate polymer, (CAB-551-0.01) and ammonio methacrylate copolymer (Eudragit RL 100) and to study the effect of this encapsulation on the drug release properties. Polymers were used separately and in combination to prepare different microspheres. Also, the effect of polymer solution phase viscosity was studied for each of the polymers and for their combinations. An Ostwald viscometer was used to evaluate the relative viscosities of polymer solution phases and their combinations. Microspheres with 25% theoretical drug loading of 6-n-propyl-2-thiouracil core material were prepared by the emulsion solvent evaporation method. Microspheres prepared from CAB-551-0.01, which has higher relative polymer phase viscosity than Eudragit RL 100, showed significantly lower drug release rates and a noticeable lag time. Polymer combinations of CAB-551-0.01 and Eudragit RL 100 (1:1) showed an interesting synergistic increase in relative polymer solution viscosities at all concentrations. Unlike microspheres prepared from the two polymers separately which follow Higuchi spherical matrix release kinetics, microspheres prepared using a combination (1:1) of the two polymers showed near zero order with faster rates compared to those prepared using CAB-551-0.01 equivalent polymer concentrations. The results of this study suggest that 6-n-propyl-2-thiouracil was successfully and efficiently encapsulated and release rates of matrix microspheres are related to polymer solution phase viscosity, but when polymer combinations were used other factors such as structural effects must be considered.

  16. Preparation of magnetite-loaded silica microspheres for solid-phase extraction of genomic DNA from soy-based foodstuffs.

    PubMed

    Shi, Ruobing; Wang, Yucong; Hu, Yunli; Chen, Lei; Wan, Qian-Hong

    2009-09-04

    Solid-phase extraction has been widely employed for the preparation of DNA templates for polymerase chain reaction (PCR)-based analytical methods. Among the variety of adsorbents studied, magnetically responsive silica particles are particularly attractive due to their potential to simplify, expedite, and automate the extraction process. Here we report a facile method for the preparation of such magnetic particles, which entails impregnation of porous silica microspheres with iron salts, followed by calcination and reduction treatments. The samples were characterized using powder X-ray diffractometry (XRD), scanning electron microscopy (SEM), nitrogen adsorption/desorption isotherms, and vibrating sample magnetometry (VSM). XRD data show that magnetite nanocrystals of about 27.2 nm are produced within the pore channels of the silica support after reduction. SEM images show that the as-synthesized particles exhibit spherical shape and uniform particle size of about 3 microm as determined by the silica support. Nitrogen sorption data confirm that the magnetite-loaded silica particles possess typical mesopore structure with BET surface area of about 183 m(2)/g. VSM data show that the particles display paramagnetic behavior with saturation magnetization of 11.37 emu/g. The magnetic silica microspheres coated with silica shells were tested as adsorbents for rapid extraction of genomic DNA from soybean-derived products. The purified DNA templates were amplified by PCR for screening of genetically modified organisms (GMOs). The preliminary results confirm that the DNA extraction protocols using magnetite-loaded silica microspheres are capable of producing DNA templates which are inhibitor-free and ready for downstream analysis.

  17. Process for preparing metal-carbide-containing microspheres from metal-loaded resin beads

    DOEpatents

    Beatty, Ronald L.

    1977-01-01

    An improved process for producing porous spheroidal particles consisting of a metal carbide phase dispersed within a carbon matrix is described. According to the invention metal-loaded ion-exchange resin microspheres which have been carbonized are coated with a buffer carbon layer prior to conversion of the oxide to carbide in order to maintain porosity and avoid other adverse sintering effects.

  18. Preparation and characterization of gelatin-hydroxyapatite composite microspheres for hard tissue repair.

    PubMed

    Chao, Shao Ching; Wang, Ming-Jia; Pai, Nai-Su; Yen, Shiow-Kang

    2015-12-01

    Gelatin-hydroxyapatite composite microspheres composed of 21% gelatin (G) and 79% hydroxyapatite (HA) with uniform morphology and controllable size were synthesized from a mixed solution of Ca(NO3)2, NH4H2PO4 and gelatin by a wet-chemical method. Material analyses such as X-ray diffraction (XRD), scanning/transmission electron microscopy examination (SEM/TEM) and inductively coupled plasma-mass spectroscopy (ICP-MS) were used to characterize G-HA microspheres by analyzing their crystalline phase, microstructure, morphology and composition. HA crystals precipitate along G fibers to form nano-rods with diameters of 6-10nm and tangle into porous microspheres after blending. The cell culture indicates that G-HA composite microspheres without any toxicity could enhance the proliferation and differentiation of osteoblast-like cells. In a rat calvarial defect model, G-HA bioactive scaffolds were compared with fibrin glue (F) and Osteoset® Bone Graft Substitute (OS) for their capacity of regenerating bone. Four weeks post-implantation, new bone, mineralization, and expanded blood vessel area were found in G-HA scaffolds, indicating greater osteoconductivity and bioactivity than F and OS.

  19. Preparation of molecularly imprinted polymeric microspheres based on distillation-precipitation polymerization for an ultrasensitive electrochemical sensor.

    PubMed

    Liu, Yuan; Zhang, Lu; Zhao, Na; Han, Yajie; Zhao, Feilang; Peng, Zhengchun; Li, Yingchun

    2017-03-08

    A highly sensitive electrochemical sensor based on a carbon paste electrode (CPE) modified with molecularly imprinted polymeric microspheres (MIPMSs) was developed for the determination of bisphenol A (BPA). For the first time BPA-imprinted MIPMSs were prepared via distillation precipitation polymerization, and then the polymeric microspheres were involved in producing the MIPMS-modified CPE (MIPMS/CPE). The polymers obtained were observed via a scanning electron microscope and its dynamic and static adsorption performances were investigated. Cyclic voltammetry and electrochemical impedance spectroscopy were performed to study the preparation process and electrochemical behavior of the modified carbon paste electrodes with [Fe(CN)6](3-/4-) ions acting as electrical indicators. Compared with the bulk MIP packed sensor, the MIPMS/CPE exhibits a higher sensing response and better reproducibility. The detection linear range for BPA is 1 × 10(-11)-1 × 10(-7) M with a detection limit of 2.8 × 10(-12) M (S/N = 3) under the optimal experimental conditions. Moreover, the MIPMS/CPE exhibited good selectivity and stability. The developed sensor can determine BPA in real samples including soil, milk and water rapidly and accurately after simple sample pretreatment.

  20. Biological Effects of Drug-Free Alginate Beads Cross-Linked by Copper Ions Prepared Using External Ionotropic Gelation.

    PubMed

    Pavelková, M; Kubová, K; Vysloužil, J; Kejdušová, M; Vetchý, D; Celer, V; Molinková, D; Lobová, D; Pechová, A; Vysloužil, J; Kulich, P

    2016-08-08

    External ionotropic gelation offers a unique possibility to entrap multivalent ions in a polymer structure. The aim of this experimental study was to prepare new drug-free sodium alginate (ALG) particles cross-linked by Cu(2+) ions and to investigate their technological parameters (particle size, sphericity, surface topology, swelling capacity, copper content, release of Cu(2+) ions, mucoadhesivity) and biological activity (cytotoxicity and efficiency against the most common vaginal pathogens-Herpes simplex, Escherichia coli, Candida albicans) with respect to potential vaginal administration. Beads prepared from NaALG dispersions (3 or 4%) were cross-linked by Cu(2+) ions (0.5 or 1.0 M CuCl2) using external ionotropic gelation. Prepared mucoadhesive beads with particle size over 1000 μm exhibited sufficient sphericity (all ˃0.89) and copper content (214.8-249.07 g/kg), which increased with concentration of polymer and hardening solution. Dissolution behaviour was characterized by extended burst effect, followed by 2 h of copper release. The efficiency of all samples against the most common vaginal pathogens was observed at cytotoxic Cu(2+) concentrations. Anti-HSV activity was demonstrated at a Cu(2+) concentration of 546 mg/L. Antibacterial activity of beads (expressed as minimum inhibition concentration, MIC) was influenced mainly by the rate of Cu(2+) release which was controlled by the extent of swelling capacity. Lower MIC values were found for E. coli in comparison with C. albicans. Sample ALG-3_1.0 exhibited the fastest copper release and was proved to be the most effective against both bacteria. This could be a result of its lower polymer concentration in combination with smaller particle size and thus larger surface area.

  1. Formulation and preparation of stable cross-linked alginate-zinc nanoparticles in the presence of a monovalent salt.

    PubMed

    Pistone, Sara; Qoragllu, Dafina; Smistad, Gro; Hiorth, Marianne

    2015-07-28

    Polysaccharide-based nanoparticles can be formed, under the right conditions, when a counterion is added to a dilute polysaccharide solution. In this study, the possibility of preparing stable alginate nanoparticles cross-linked with zinc was investigated. The effects of the ionic strength of the solvent and the concentration of zinc were studied. The nanoparticles were characterized by dynamic light scattering, zeta potential and pH measurements. The results showed that an increase in the ionic strength of the solvent provided nanoparticles with considerably narrower size distributions compared to pure water, and a small size. The zinc content was shown to be an important factor for the formation of the nanoparticles. In fact, a critical zinc concentration was needed to obtain nanoparticles, and below this concentration particles were not formed. A stepwise increase in the amount of zinc revealed the process of formation of the nanoparticles. The stages of the nanoparticle formation process were identified, and differences according to the ionic strength of the solvent were also reported. Furthermore, the stability test of the most promising formulation showed a stability of over ten weeks.

  2. Preparation and characterization of luminescent CdS nanoparticles immobilized on poly(St-co-GMA-IDA) polymer microspheres

    NASA Astrophysics Data System (ADS)

    Chu, Yuan-Chih; Wang, Cheng-Chien; Huang, Yao-Hui; Chen, Chuh-Yung

    2005-04-01

    Luminescent CdS nanoparticles immobilized on copolymer microspheres were produced by the chemical precipitation of poly(St-co-GMA-IDA)-Cd2+ (PSG-Cd2+) complexes. PSG latex was prepared by the soap-free emulsion copolymerization of styrene (St) and 2-methacrylic acid 3-(bis-carboxymethylamino)-2-hydroxy-propyl ester (GMA-IDA). GMA-IDA chelating groups within copolymer latex have coordination sites for chelating metal ions, at which CdS particles were grown. The presence of ethanol as a cosolvent improved both the particle monodispersity and the surface charge. Fourier transform infrared (FT-IR) spectroscopy spectra were obtained to elucidate the characteristics of GMA-IDA in the PSG latex. The size distribution, morphology and structure of CdS nanoparticles were measured by transmission electron microscope (TEM) and x-ray diffraction (XRD) analysis. The growth kinetics of CdS nanoparticles were studied by TEM and obtaining photoluminescence (PL) spectra. The size and morphology of CdS particles were influenced by the amount of the chelating, iminodiacetic acid group on the surface of the copolymer microsphere, the concentration of Cd2+ ions and the pH. The PSG-A3-CdS sample with [Cd2+]/[GMA-IDA] = 1/6, pH = 3.5, which was formed from ultrafine CdS particles with mean diameters below 5 nm immobilized on the surface of copolymer microspheres, emitted photons with a higher energy than other samples in this investigation.

  3. In-vitro and in-vivo evaluation of repaglinide loaded floating microspheres prepared from different viscosity grades of HPMC polymer

    PubMed Central

    Sharma, Megha; Kohli, Seema; Dinda, Agnimitra

    2015-01-01

    During the study repaglinide encapsulated floating microspheres were formulated and characterized for enhancing residence time of drug in git and thereby increasing its bioavailability. Floating microspheres of ethylcellulose (EC) and hydroxypropyl methyl cellulose (HPMC) (5 and 100 cps) were prepared by emulsion solvent diffusion technique. During process optimization various parameters were studied such as: drug: polymer ratio, polymer ratio, concentration of emulsifier and stirring speed. Selected optimized formulations were studied for SEM, entrapment, floating behavior, drug release and kinetics. In-vivo floating ability (X-ray) study and in-vivo antidiabetic activity were performed on alloxan induced diabetic rats. Microspheres prepared with different viscosity grade HPMC were spherical shaped with smooth surface. Size of microspheres was in the range of 181.1–248 μm. Good entrapment and buoyancy were observed for 12 h. X-ray image showed that optimized formulation remained buoyant for more than 6 h. Optimized formulation treated group shows significant (p < 0.01) reduction in blood glucose level as compared to pure drug treated group. Repaglinide loaded floating microspheres expected to give new choice for safe, economical and increased bioavailable formulation for effective management of NIDDM. PMID:26702263

  4. Liquid phase synthesis: preparation of co microspheres by hydrazine reducing method

    NASA Astrophysics Data System (ADS)

    Deng, Y.; Lu, Z. Q.; Xie, F.; Liang, H.; Wang, Y. J.; Du, X. H.

    2017-01-01

    The study synthesizes Co microspheres with perfect spherical shape by use hydrazine hydrate as reducing agent to reduce CoCl2 in alkaline conditions at room temperature, the influence of NaOH addition amount on crystal morphology and structure of cobalt particle were studied. The results show that, under the condition of concentration of NaOH, 0.030g ml-1 and having ethylene glycol as solvent, are the best choice to synthesize Co microspheres, and the grain is smaller, suitable for industrial production. At the condition of less amount of NaOH, cobalt particle's surface is smooth spherical, and with the increase of NaOH, particles will deviate from the spherical morphology and the surface become rough. The first section in your paper

  5. Activation of the Solid Silica Layer of Aerosol-Based C/SiO₂ Particles for Preparation of Various Functional Multishelled Hollow Microspheres.

    PubMed

    Li, Xiangcun; Luo, Fan; He, Gaohong

    2015-05-12

    Double-shelled C/SiO2 hollow microspheres with an outer nanosheet-like silica shell and an inner carbon shell were reported. C/SiO2 aerosol particles were synthesized first by a one-step rapid aerosol process. Then the solid silica layer of the aerosol particles was dissolved and regrown on the carbon surface to obtain novel C/SiO2 double-shelled hollow microspheres. The new microspheres prepared by the facile approach possess high surface area and pore volume (226.3 m(2) g(-1), 0.51 cm(3) g(-1)) compared with the original aerosol particles (64.3 m(2) g(-1), 0.176 cm(3) g(-1)), providing its enhanced enzyme loading capacity. The nanosheet-like silica shell of the hollow microspheres favors the fixation of Au NPs (C/SiO2/Au) and prevents them from growing and migrating at 500 °C. Novel C/C and C/Au/C (C/Pt/C) hollow microspheres were also prepared based on the hollow nanostructure. C/C microspheres (482.0 m(2) g(-1), 0.92 cm(3) g(-1)) were ideal electrode materials. In particular, the Au NPs embedded into the two carbon layers (C/Au/C, 431.2 m(2) g(-1), 0.774 cm(3) g(-1)) show a high catalytic activity and extremely chemical stability even at 850 °C. Moreover, C/SiO2/Au, C/Au/C microspheres can be easily recycled and reused by an external magnetic field because of the presence of Fe3O4 species in the inner carbon shell. The synthetic route reported here is expected to simplify the fabrication process of double-shelled or yolk-shell microspheres, which usually entails multiple steps and a previously synthesized hard template. Such a capability can facilitate the preparation of various functional hollow microspheres by interfacial design.

  6. Preparation and optical properties of alloyed Znx Cd1-x S/alginate core/shell nanoparticles.

    PubMed

    Wang, Liping; Sun, Yujie

    2015-02-01

    Znx Cd1-x S/alginate core/shell nanoparticles were synthesized via a colloidal route by reacting zinc and cadmium ions with sulfide ions, followed by coating with alginate. The crystal structure, morphology, size and optical properties of the core/shell nanoparticles were characterized by X-ray diffraction, transmission electron microscopy, UV/vis and photoluminescent spectra, respectively. The Znx Cd1-x S nanoparticles are spherical and have a cubic structure with a mean crystalline size of 2-4 nm. The band gap of Znx Cd1-x S/alginate core/shell nanoparticles increases with increasing Zn/Cd molar ratio, and the UV/vis absorption blue-shifts correspondingly. Two emissions related to zinc and sulfide ion vacancies were observed for the Znx Cd1-x S/alginate core/shell nanoparticles due to the surface changes from the alginate coating. A cadmium-related emission was observed for both the uncovered Znx Cd1-x S and Znx Cd1-x S/alginate core/shell nanoparticles, which has a significant blue-shift with increasing Zn/Cd molar ratio.

  7. Papain wound dressings obtained from poly(vinyl alcohol)/calcium alginate blends as new pharmaceutical dosage form: Preparation and preliminary evaluation.

    PubMed

    Dutra, J A P; Carvalho, S G; Zampirolli, A C D; Daltoé, R D; Teixeira, R M; Careta, F P; Cotrim, M A P; Oréfice, R L; Villanova, J C O

    2017-04-01

    Transparent, soft, flexible, mechanically resistant films, which are ideal for use as wound dressings were prepared in the presence of 2% papain, a proteolytic enzyme that can play a role in the chemical debridement of the skin and can accelerate the healing process. The films, based on poly(vinyl alcohol):calcium alginate blends with increasing concentrations of polysaccharide (10, 20, and 30% v/v), were obtained by casting method. FTIR and DSC analyses were performed to assess the composition and miscibility of blends. Mechanical properties such as tensile strength, elasticity modulus, and elongation at breakpoint were evaluated. The influence of different concentrations of calcium alginate on physical attributes of films like wettability, swelling capacity and mechanical properties was determined. The stability of papain in the films was assessed indirectly by hemolytic activity assay employing direct contact method and confirmed by technique based on blood agar diffusion. Preliminary cytotoxicity was evaluated with the XTT method. The results showed that at the polymer concentrations tested, the blends were miscible. The increase in the content of the calcium alginate increased the wettability and swelling capacity of the films, which is desirable in wound dressings. On the other hand, mechanical resistance decreased without causing breakage of the films during the swelling tests. The hemolytic activity of the films was maintained during the studied period, suggesting the stability of papain in the proposed formulations. Cellular viability indicated that the films were non-toxic. The analysis of the results showed that it is possible to prepare interactive and bioactive wound dressing containing papain from blends of PVA and calcium alginate polymers.

  8. A novel and simple preparative method for uniform-sized PLGA microspheres: Preliminary application in antitubercular drug delivery.

    PubMed

    Liu, Zhiqiang; Li, Xia; Xiu, Bingshui; Duan, Cuimi; Li, Jiangxue; Zhang, Xuhui; Yang, Xiqin; Dai, Wenhao; Johnson, Heather; Zhang, Heqiu; Feng, Xiaoyan

    2016-09-01

    Particle size has been demonstrated as a key parameter influencing the phagocytosis of drug-loaded PLGA microspheres (MS) by the target cells. However, the current preparative methods were either insufficient in controlling the homogeneity of the produced MS, or requires sophisticated and costly equipment. This study aimed to explore a simple and economical method for uniform PLGA MS preparation. Based on the heterogeneous emulsification of routine mechanical stirring, we designed an adjuvant strategy to enhance the homogeneity of MS. By using glass beads as adjutant, the dispersion produced during mechanical stirring was much more homogeneous in the solution. The particles produced were much smaller and the size distribution was much narrower as compared with those produced using the routine mechanical stirring method under the same condition. After enrichment by selective centrifugation, about 60% of the particles of similar size were obtained, providing further evidence for the efficiency of the novel method in controlling particle homogeneity. Further, the method was applied to prepare rifampicin-loaded PLGA MS of the optimized size for macrophage uptake. The functional evaluation showed that the prepared PLGA MS could efficiently deliver an antitubercular drug into macrophages and maintain a higher intracellular concentration by controlled release, suggesting the potential application of the method in PLGA MS-based drug delivery. Collectively, the study provided a simple and economical method for preparing uniform-sized PLGA MS with potential of widespread applications.

  9. Preparation of novel poly(hydroxyethyl methacrylate-co-glycidyl methacrylate)-grafted core-shell magnetic chitosan microspheres and immobilization of lactase.

    PubMed

    Zhao, Wei; Yang, Rui-Jin; Qian, Ting-Ting; Hua, Xiao; Zhang, Wen-Bin; Katiyo, Wendy

    2013-06-06

    Poly(hydroxyethyl methacrylate-co-glycidyl methacrylate)-grafted magnetic chitosan microspheres (HG-MCM) were prepared using reversed-phase suspension polymerization method. The HG-MCM presented a core-shell structure and regular spherical shape with poly(hydroxyethyl methacrylate-co-glycidyl methacrylate) grafted onto the chitosan layer coating the Fe3O4 cores. The average diameter of the magnetic microspheres was 10.67 μm, within a narrow size distribution of 6.6-17.4 μm. The saturation magnetization and retentivity of the magnetic microspheres were 7.0033 emu/g and 0.6273 emu/g, respectively. The application of HG-MCM in immobilization of lactase showed that the immobilized enzyme presented higher storage, pH and thermal stability compared to the free enzyme. This indicates that HG-MCM have potential applications in bio-macromolecule immobilization.

  10. Preparation of resorbable carbonate-substituted hollow hydroxyapatite microspheres and their evaluation in osseous defects in vivo

    PubMed Central

    Xiao, Wei; Bal, B. Sonny; Rahaman, Mohamed N.

    2015-01-01

    Hollow hydroxyapatite (HA) microspheres, with a high-surface-area mesoporous shell, can provide a unique bioactive and osteoconductive carrier for proteins to stimulate bone regeneration. However, synthetic HA has a slow resorption rate and a limited ability to remodel into bone. In the present study, hollow HA microspheres with controllable amounts of carbonate substitution (0–12 wt. %) were created using a novel glass conversion route and evaluated in vitro and in vivo. Hollow HA microspheres with ~12 wt. % of carbonate (designated CHA12) showed a higher surface area (236 m2g−1) than conventional hollow HA microspheres (179 m2g−1) and a faster degradation rate in a potassium acetate buffer solution. When implanted for 12 weeks in rat calvarial defects, the CHA12 and HA microspheres showed a limited capacity to regenerate bone but the CHA12 microspheres resorbed faster than the HA microspheres. Loading the microspheres with bone morphogenetic protein-2 (BMP2) (1 μg per defect) stimulated bone regeneration and accelerated resorption of the CHA12 microspheres. At 12 weeks, the amount of new bone in the defects implanted with the CHA12 microspheres (73 ± 8 %) was significantly higher than the HA microspheres (59 ± 2%) while the amount of residual CHA12 microspheres (7 ± 2% of the total defect area) was significantly lower than the HA microspheres (21 ± 3%). The combination of these carbonate-substituted HA microspheres with clinically safe doses of BMP2 could provide promising implants for healing non-loaded bone defects. PMID:26706537

  11. Preparation of resorbable carbonate-substituted hollow hydroxyapatite microspheres and their evaluation in osseous defects in vivo.

    PubMed

    Xiao, Wei; Bal, B Sonny; Rahaman, Mohamed N

    2016-03-01

    Hollow hydroxyapatite (HA) microspheres, with a high-surface-area mesoporous shell, can provide a unique bioactive and osteoconductive carrier for proteins to stimulate bone regeneration. However, synthetic HA has a slow resorption rate and a limited ability to remodel into bone. In the present study, hollow HA microspheres with controllable amounts of carbonate substitution (0-12 wt.%) were created using a novel glass conversion route and evaluated in vitro and in vivo. Hollow HA microspheres with ~12 wt.% of carbonate (designated CHA12) showed a higher surface area (236 m(2) g(-1)) than conventional hollow HA microspheres (179 m(2)g(-1)) and a faster degradation rate in a potassium acetate buffer solution. When implanted for 12 weeks in rat calvarial defects, the CHA12 and HA microspheres showed a limited capacity to regenerate bone but the CHA12 microspheres resorbed faster than the HA microspheres. Loading the microspheres with bone morphogenetic protein-2 (BMP2) (1 μg per defect) stimulated bone regeneration and accelerated resorption of the CHA12 microspheres. At 12 weeks, the amount of new bone in the defects implanted with the CHA12 microspheres (73±8%) was significantly higher than the HA microspheres (59±2%) while the amount of residual CHA12 microspheres (7±2% of the total defect area) was significantly lower than the HA microspheres (21±3%). The combination of these carbonate-substituted HA microspheres with clinically safe doses of BMP2 could provide promising implants for healing non-loaded bone defects.

  12. Preparation of Co3O4/crumpled graphene microsphere as peroxidase mimetic for colorimetric assay of ascorbic acid.

    PubMed

    Fan, Sisi; Zhao, Minggang; Ding, Longjiang; Li, Hui; Chen, Shougang

    2017-03-15

    The well-dispersed Co3O4 nanoparticles-decorated crumpled graphene microsphere (CGM) was successfully prepared by aerosol-assisted frying self-assembly and annealing process. It is found that the obtained Co3O4/CGM nanohybrid possessed enhanced intrinsic peroxidase-like activity and could catalytically oxidize 3,3',5,5'-tetramethylbenzidine by H2O2 to produce a typical blue product. But the presence of ascorbic acid could induce the reduction of oxTMB to TMB, resulting in a significant blue color fading. Therefore, a simple, sensitive and selective colorimetric method to detect ascorbic acid was established with a good linear relationship (30-140μM) and a low detection limit of 0.19μM. Meanwhile, the selectivity, stability and repeatability were acceptable. It is also a facile route to fabricate nanoparticles/CGM as high-performance enzyme mimetic for colorimetric biosensing.

  13. High-strength lightweight concrete mixtures based on hollow microspheres: technological features and industrial experience of preparation

    NASA Astrophysics Data System (ADS)

    Inozemtcev, A. S.

    2015-01-01

    The research results concerning dependencies between technological parameters and physical properties of structural lightweight concrete are presented in the article. High-strength lightweight concrete has unique performance characteristics: low average density (less than 1500 kg/m3) and high compressive strength (more than 70 MPa). Hollow alumina-silicate microspheres with nanoscale modifier are used for obtaining these properties. It is shown in the article that the preparation of high-strength lightweight concrete in industrial conditions must be implemented using a turbine mixer having six paddles and engine power more than 39.2 kW. Oscillation frequency of more than 3000 rpm, vibro-compacting time less than 15 seconds, heat-humid treatment temperature approximately 60-65 °C and heat-humid treatment time 6-7 hours are optimal for production. The results of industrial mixing-test are presented.

  14. Engineering alginate for intervertebral disc repair.

    PubMed

    Bron, Johannes L; Vonk, Lucienne A; Smit, Theodoor H; Koenderink, Gijsje H

    2011-10-01

    Alginate is frequently studied as a scaffold for intervertebral disc (IVD) repair, since it closely mimics mechanical and cell-adhesive properties of the nucleus pulposus (NP) of the IVD. The aim of this study was to assess the relation between alginate concentration and scaffold stiffness and find preparation conditions where the viscoelastic behaviour mimics that of the NP. In addition, we measured the effect of variations in scaffold stiffness on the expression of extracellular matrix molecules specific to the NP (proteoglycans and collagen) by native NP cells. We prepared sample discs of different concentrations of alginate (1%-6%) by two different methods, diffusion and in situ gelation. The stiffness increased with increasing alginate concentration, while the loss tangent (dissipative behaviour) remained constant. The diffusion samples were ten-fold stiffer than samples prepared by in situ gelation. Sample discs prepared from 2% alginate by diffusion closely matched the stiffness and loss tangent of the NP. The stiffness of all samples declined upon prolonged incubation in medium, especially for samples prepared by diffusion. The biosynthetic phenotype of native cells isolated from NPs was preserved in alginate matrices up to 4 weeks of culturing. Gene expression levels of extracellular matrix components were insensitive to alginate concentration and corresponding matrix stiffness, likely due to the poor adhesiveness of the cells to alginate. In conclusion, alginate can mimic the viscoelastic properties of the NP and preserve the biosynthetic phenotype of NP cells but certain limitations like long-term stability still have to be addressed.

  15. Process and formulation variables of pregabalin microspheres prepared by w/o/o double emulsion solvent diffusion method and their clinical application by animal modeling studies.

    PubMed

    Aydogan, Ebru; Comoglu, Tansel; Pehlivanoglu, Bilge; Dogan, Murat; Comoglu, Selcuk; Dogan, Aysegul; Basci, Nursabah

    2015-01-01

    Pregabalin is an anticonvulsant drug used for neuropathic pain and as an adjunct therapy for partial seizures with or without secondary generalization in adults. In conventional therapy recommended dose for pregabalin is 75 mg twice daily or 50 mg three times a day, with maximum dosage of 600 mg/d. To achieve maximum therapeutic effect with a low risk of adverse effects and to reduce often drug dosing, modified release preparations; such as microspheres might be helpful. However, most of the microencapsulation techniques have been used for lipophilic drugs, since hydrophilic drugs like pregabalin, showed low-loading efficiency and rapid dissolution of compounds into the aqueous continous phase. The purpose of this study was to improve loading efficiency of a water-soluble drug and modulate release profiles, and to test the efficiency of the prepared microspheres with the help of animal modeling studies. Pregabalin is a water soluble drug, and it was encapsulated within anionic acrylic resin (Eudragit S 100) microspheres by water in oil in oil (w/o/o) double emulsion solvent diffusion method. Dichloromethane and corn oil were chosen primary and secondary oil phases, respectively. The presence of internal water phase was necessary to form stable emulsion droplets and it accelerated the hardening of microspheres. Tween 80 and Span 80 were used as surfactants to stabilize the water and corn oil phases, respectively. The optimum concentration of Tween 80 was 0.25% (v/v) and Span 80 was 0.02% (v/v). The volume of the continous phase was affected the size of the microspheres. As the volume of the continous phase increased, the size of microspheres decreased. All microsphere formulations were evaluated with the help of in vitro characterization parameters. Microsphere formulations (P1-P5) exhibited entrapment efficiency ranged between 57.00 ± 0.72 and 69.70 ± 0.49%; yield ranged between 80.95 ± 1.21 and 93.05 ± 1.42%; and mean particle size were

  16. Photochemical preparation of CdS hollow microspheres at room temperature and their use in visible-light photocatalysis

    NASA Astrophysics Data System (ADS)

    Huang, Yuying; Sun, Fengqiang; Wu, Tianxing; Wu, Qingsong; Huang, Zhong; Su, Heng; Zhang, Zihe

    2011-03-01

    CdS hollow microspheres have been successfully prepared by a photochemical preparation technology at room temperature, using polystyrene latex particles as templates, CdSO 4 as cadmium source and Na 2S 2O 3 as both sulphur source and photo-initiator. The process involved the deposition of CdS nanoparticles on the surface of polystyrene latex particles under the irradiation of an 8 W UV lamp and the subsequent removal of the latex particles by dispersing in dichloromethane. Photochemical reactions at the sphere/solution interface should be responsible for the formation of hollow spheres. The as-prepared products were characterized by X-ray diffraction, transmission electron microscopy and scanning electron microscopy. Such hollow spheres could be used in photocatalysis and showed high photocatalytic activities in photodegradation of methyl blue (MB) in the presence of H 2O 2. The method is green, simple, universal and can be extended to prepare other sulphide and oxide hollow spheres.

  17. Preparation of Eleutherine americana-Alginate Complex Microcapsules and Application in Bifidobacterium longum

    PubMed Central

    Phoem, Atchara N; Chanthachum, Suphitchaya; Voravuthikunchai, Supayang P

    2015-01-01

    Microencapsulation using extrusion and emulsion techniques was prepared for Bifidobacterium longum protection against sequential exposure to simulated gastric and intestinal juices, refrigeration storage and heat treatment. Eleutherine americana was used as the co-encapsulating agent. Hydrolysis of E. americana by gastric and intestinal juices was also determined. E. americana and its oligosaccharide extract demonstrated their resistance to low pH and partial tolerance to human α-amylase. Microencapsulated B. longum with E. americana and oligosaccharide extract prepared by the extrusion technique survived better than that by the emulsion technique under adverse conditions. Survival of microencapsulated cells after exposure to the juices and refrigeration storage was higher than free cells at Weeks 2 and 4. In addition, the viability of microencapsulated cells was better than free cells at 65 °C for 15 min. This work suggested that microencapsulated B. longum with E. americana offers the effective delivery of probiotics to colon and maintains their survival in food products. PMID:25629556

  18. Development of Floating-Mucoadhesive Microsphere for Site Specific Release of Metronidazole

    PubMed Central

    Amin, Md. Lutful; Ahmed, Tajnin; Mannan, Md. Abdul

    2016-01-01

    Purpose: The purpose of this study was to develop and evaluate metronidazole loaded floating-mucoadhesive microsphere for sustained drug release at the gastric mucosa. Methods: Alginate gastroretentive microspheres containing metronidazole were prepared by ionic gelation method using sodium bicarbonate as gas forming agent, guar gum as mucoadhesive polymer, and Eudragit L100 as drug release modifier. Carbopol was used for increasing the bead strength. The microspheres were characterized by scanning electron microscopy and evaluated by means of drug entrapment efficiency, in vitro buoyancy, and swelling studies. In vitro mucoadhesion and drug release studies were carried out in order to evaluate site specific sustained drug release. Results: All formulations showed 100% buoyancy in vitro for a prolonged period of time. Amount of guar gum influenced the properties of different formulations. The formulation containing drug and guar gum at a ratio of 1:0.5 showed the best results with 76.3% drug entrapment efficiency, 61.21% mucoadhesion, and sustained drug release. Carbopol was found to increase surface smoothness of the microspheres. Conclusion: Metronidazole mucoadhesive-floating microspheres can be effectively used for sustained drug release to the gastric mucosa in treatment of upper GIT infection. PMID:27478781

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

    PubMed

    Ashida, Tomoaki; Sakai, Shinji; Taya, Masahito

    2016-09-01

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

  20. An investigation and characterization on alginate hydogel dressing loaded with metronidazole prepared by combined inotropic gelation and freeze-thawing cycles for controlled release.

    PubMed

    Sarheed, Omar; Rasool, Bazigha K Abdul; Abu-Gharbieh, Eman; Aziz, Uday Sajad

    2015-06-01

    The purpose of this study was to investigate the effect of combined Ca(2+) cross-linking and freeze-thawing cycle method on metronidazole (model drug) drug release and prepare a wound film dressing with improved swelling property. The hydrogel films were prepared with sodium alginate (SA) using the freeze-thawing method alone or in combination with ionotropic gelation with CaCl2. The gel properties such as morphology, swelling, film thickness, and content uniformity and in vitro dissolution profiles using Franz diffusion cell were investigated. The cross-linking process was confirmed by differential scanning calorimetry (DSC) and Fourier transform infrared (FTIR) spectroscopy. In vitro protein adsorption test, in vivo wound-healing test, and histopathology were also performed. The hydrogel (F2) composed of 6% sodium alginate and 1% metronidazole prepared by combined Ca(2+) cross-linking and freeze-thawing cycles showed good swelling. This will help to provide moist environment at the wound site. With the in vivo wound-healing and histological studies, F2 was found to improve the wound-healing effect compared with the hydrogel without the drug, and the conventional product.

  1. Preparation, characterization, and infrared emissivity property of optically active polyurethane/TiO{sub 2}/SiO{sub 2} multilayered microspheres

    SciTech Connect

    Yang Yong; Zhou Yuming; Ge Jianhua; Wang Yongjuan; Zhu Yunxia

    2011-10-15

    Optically active polyurethane/titania/silica (LPU/TiO{sub 2}/SiO{sub 2}) multilayered core-shell composite microspheres were prepared by the combination of titania deposition on the surface of silica spheres and subsequent polymer grafting. LPU/TiO{sub 2}/SiO{sub 2} was characterized by FT-IR, UV-vis spectroscopy, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), SEM and TEM, and the infrared emissivity value (8-14 {mu}m) was investigated in addition. The results indicated that titania and polyurethane had been successfully coated onto the surfaces of silica microspheres. LPU/TiO{sub 2}/SiO{sub 2} exhibited clearly multilayered core-shell construction. The infrared emissivity values reduced along with the increase of covering layers thus proved that the interfacial interactions had direct influence on the infrared emissivity. Besides, LPU/TiO{sub 2}/SiO{sub 2} multilayered microspheres based on the optically active polyurethane took advantages of the orderly secondary structure and strengthened interfacial synergistic actions. Consequently, it possessed the lowest infrared emissivity value. - Graphical Abstract: Optically active polyurethane/titania/silica (LPU/TiO{sub 2}/SiO{sub 2}) multilayered core-shell composite microspheres were prepared by the combination of titania deposition on the surface of silica spheres and subsequent polymer grafting. Highlights: > Optically active polyurethane based on tyrosine was used for the modification of nanoparticles. > LPU/TiO{sub 2}/SiO{sub 2} multilayered core-shell microspheres were prepared and characterized. > Interfacial interactions and secondary structure affected the infrared emissivity of composite.

  2. Preparation of magnetic core-mesoporous shell microspheres with C8-modified interior pore-walls and their application in selective enrichment and analysis of mouse brain peptidome.

    PubMed

    Liu, Shasha; Li, Yan; Deng, Chunhui; Mao, Yu; Zhang, Xiangmin; Yang, Pengyuan

    2011-12-01

    In this paper, magnetic mesoporous silica microspheres with C8-modified interior pore-walls were prepared through a facile one-pot sol-gel coating strategy, and were successfully applied for selective enrichment of endogenous peptides in mouse brain for peptidome analysis. Through the one-pot sol-gel approach with surfactant (CTAB) as a template, tetraethyl orthosilicate (TEOS) and n-ctyltriethoxysilane (C8TEOS) as the precursors, C8-modified magnetic mesoporous microspheres (C8-Fe(3)O(4)@mSiO(2)) consisting magnetic core and mesoporous silica shell with C8-groups exposed in the mesopore channels were synthesized. The obtained microspheres possess highly open mesopores of 3.4 nm, high surface area (162.5 m(2)/g), large pore volume (0.17 cm(3)/g), excellent magnetic responsivity (56.3 emu/g) and good dispersibility in aqueous solution. Based on the abundant surface silanol groups, functional C8 groups and the strong magnetic responsivity of the core-shell C8-Fe(3) O(4) @mSiO(2) microspheres, efficient and fast enrichment of peptides was achieved. Additionally, the C8-Fe(3)O(4)@mSiO(2) microspheres exhibit excellent performance in selective enrichment of endogenous peptides from complex samples that are consist of peptides, large proteins and other compounds, including human serum and mouse brain followed by automated nano-LC-ESI-MS/MS analysis. These results indicate C8-Fe(3)O(4)@mSiO(2) microspheres would be a potential candidate for endogenous peptides enrichment and biomarkers discovery in peptidome analysis.

  3. Molecularly imprinted microspheres and nanoparticles prepared using precipitation polymerisation method for selective extraction of gallic acid from Emblica officinalis.

    PubMed

    Pardeshi, Sushma; Dhodapkar, Rita; Kumar, Anupama

    2014-03-01

    This paper reports the preparation of gallic acid (GA) molecularly imprinted polymers (MIPs) by the precipitation polymerisation and highlights the effect of porogen on particle size and specific molecular recognition properties. MIP, M-100 prepared in the porogen acetonitrile and MIP, M-75 prepared in a mixture of acetonitrile-toluene (75:25 v/v), resulted in the formation of microspheres with approximately 4μm particle size and surface area of 96.73m(2)g(-1) and nanoparticles (0.8-1000nm) and a surface area of 345.9m(2)g(-1), respectively. The Langmuir-Freundlich isotherm study revealed that M-75 has comparatively higher number of binding sites which are homogenous and has higher affinity for GA. The MIPs selectively recognised GA in presence of its structural analogues. Pure GA with percent recovery of 75 (±1.6) and 83.4 (±2.2) was obtained from the aqueous extract of Emblica officinalis by M-100 and M-75, respectively and hot water at 60°C served as the eluting solvent.

  4. Zinc oxide nanorod growth on gold islands prepared by microsphere lithography on silicon and quartz.

    PubMed

    Blackledge, Charles W; Szarko, Jodi M; Dupont, Aurélie; Chan, George H; Read, Elizabeth L; Leone, Stephen R

    2007-09-01

    Gold islands, vapor deposited on silicon and quartz by microsphere lithography patterning, are used to nucleate arrays of ZnO nanorods. ZnO is grown on approximately 0.32 microm2 Au islands by carbothermal reduction in a tube furnace. Scanning electron microscopy (SEM) and energy dispersive atomic X-ray spectroscopy (EDS) confirm that the gold effectively controls the sites of nucleation of ZnO. Atomic force microscopy (AFM) shows that approximately 30 nm diameter nanorods grow horizontally, along the surface. Alloy droplets that are characteristic of the vapor-liquid-solid (VLS) mechanism are observed at the tips of the nanorods. The spatial growth direction of VLS catalyzed ZnO nanorods is along the substrate when they nucleate from gold islands on silicon and quartz. The energy of adhesion of the VLS droplet to the surface can account for the horizontal growth.

  5. Preparation of novel porphyrin nanomaterials based on the pH-responsive shape evolution of porphyrin microspheres.

    PubMed

    Zhang, Wenbo; Xing, Lingbo; Wang, Haisheng; Liu, Xiujun; Feng, Yaqing; Gao, Changyou

    2015-04-14

    The shapes and properties of self-assembled materials can be adjusted easily using environmental stimuli. Yet, the stimulus-triggered shape evolution of organic microspheres in aqueous solution has rarely been reported so far. Here, a novel type of poly(allylamine hydrochloride)-g-porphyrin microspheres (PAH-g-Por MPs) was prepared by a Schiff base reaction between 2-formyl-5,10,15,20-tetraphenylporphyrin (Por-CHO) and PAH doped in 3.5-μm CaCO3 microparticles, followed by template removal. The PAH-g-Por MPs had an average diameter of 2.5 μm and could be transformed into one-dimensional nanorods (NRs) and wormlike nanostructures (WSs) after being incubated for different times in pH 1-4 HCl solutions. The rate and degree of hydrolysis had a significant effect on the formation and morphologies of the nanorods. The NRs@pH1, NRs@pH2, and NRs@pH3 were all composed of the released Por-CHO and the unhydrolyzed PAH-g-Por because of the incomplete hydrolysis of the Schiff base. However, the WSs@pH4 were formed by a pure physical shape transformation, because they had the same composition as the PAH-g-Por MPs and the Schiff base bonds were not hydrolyzed. The self-assembled NRs and WSs exhibited good colloidal stability and could emit stable red fluorescence over a relatively long period of time.

  6. Porous microsphere and its applications

    PubMed Central

    Cai, Yunpeng; Chen, Yinghui; Hong, Xiaoyun; Liu, Zhenguo; Yuan, Weien

    2013-01-01

    Porous microspheres have drawn great attention in the last two decades for their potential applications in many fields, such as carriers for drugs, absorption and desorption of substances, pulmonary drug delivery, and tissue regeneration. The application of porous microspheres has become a feasible way to address existing problems. In this essay, we give a brief introduction of the porous microsphere, its characteristics, preparation methods, applications, and a brief summary of existing problems and research tendencies. PMID:23515359

  7. Tetracycline-HCl-loaded poly(DL-lactide-co-glycolide) microspheres prepared by a spray drying technique: influence of gamma-irradiation on radical formation and polymer degradation.

    PubMed

    Bittner, B; Mäder, K; Kroll, C; Borchert, H H; Kissel, T

    1999-05-01

    Tetracycline-HCl (TCH)-loaded microspheres were prepared from poly(lactide-co-glycolide) (PLGA) by spray drying. The drug was incorporated in the polymer matrix either in solid state or as w/o emulsion. The spin probe 4-hydroxy-2,2,6, 6-tetramethyl-piperidine-1-oxyl (TEMPOL) and the spin trap tert-butyl-phenyl-nitrone (PBN) were co-encapsulated into the TCH-loaded and placebo particles. We investigated the effects of gamma-irradiation on the formation of free radicals in polymer and drug and the mechanism of chain scission after sterilization. Gamma-Irradiation was performed at 26.9 and 54.9 kGy using a 60Co source. The microspheres were characterized especially with respect to the formation of radicals and in vitro polymer degradation. Electron paramagnetic resonance (EPR) spectroscopy, gel permeation chromatography (GPC), differential scanning calorimetry (DSC), high-performance liquid chromatography (HPLC), gas chromatography-mass spectroscopy (GC-MS), and scanning electron microscopy (SEM) were used for characterization of the microspheres. Using EPR spectroscopy, we successfully detected gamma-irradiation induced free radicals within the TCH-loaded microspheres, while unloaded PLGA did not contain radicals under the same conditions. The relatively low glass transition temperature of the poly(dl-lactide-co-glycolide) (37-39 degrees C) seems to favor subsequent reactions of free radicals due to the high mobility of the polymeric chains. Because of the high melting point of TCH (214 degrees C), the radicals can only be stabilized in drug loaded microspheres. In order to determine the mechanism of polymer degradation after exposure to gamma-rays, the spin trap PBN and the spin probe TEMPOL were encapsulated in the microspheres. gamma-Irradiation of microspheres containing PBN resulted in the formation of a lipophilic spin adduct, indicating that a polymeric radical was generated by random chain scission. Polymer degradation by an unzipping mechanism would have

  8. Preparation of hollow microspheres of Ce3+ doped NiCo ferrite with high microwave absorbing performance

    NASA Astrophysics Data System (ADS)

    Duan, Hong-zhen; Zhou, Fang-ling; Cheng, Xia; Chen, Guo-hong; Li, Qiao-ling

    2017-02-01

    Hollow microspheres of Ce3+ doped NiCo-ferrites were synthesized by template-based-deposition and surface reaction method with carbon sphere as the template. The phase structure, morphology, magnetic properties and wave absorbing properties of the sample were characterized by X-ray powder diffraction(XRD), Scanning electronic microscopy(SEM), Vibration sample magnetometer (VSM) and a network vector analyzer (NVA), respectively. The results indicated that the particle size of the carbon sphere sample prepared by hydrothermal method was about 0.5 μm and the particle size of the Ni0.5Co0.5Fe2O4 sample prepared by template-based method was about 300 nm. The influence of the amount of rare earth element on the magnetic and absorbing properties of sample was studied. The saturation magnetization and coercivity decreased gradually with the increase of the content of Ce. When the content of Ce was 0.02, the maximal saturation magnetization value and coercivity was 75.72 emu•g-1 and 789.88 Oe, respectively. The associated ferrite hollow spheres have good absorbing performance, and the return loss value was -18.8 dB at 5500 MHz.

  9. A comparison of enteric coated microspheres with enteric coated tablet pancreatic enzyme preparations in cystic fibrosis. A controlled study.

    PubMed

    Vyas, H; Matthew, D J; Milla, P J

    1990-01-01

    A comparative study of the efficacy of pH sensitive enteric coated microspheres (ECM) with an enteric coated tablet (ECT) pancreatic enzyme preparation was carried out in 20 children with cystic fibrosis in a double-blind double-placebo crossover manner. Steatorrhoea was assessed by 3 day faecal fat analysis and dosage of medication, stool frequency and consistency; abdominal pain and appetite were documented by a patient-kept diary card. ECM controlled steatorrhoea (11.8 +/- 9.2 g vs 23.2 +/- 18.9 g, P less than 0.02), stool frequency (1.7 +/- 0.6 vs 2.1 +/- 0.9, P less than 0.01) and abdominal pain (8.8 +/- 13.8 vs 23.4 +/- 24.1, P less than 0.05) significantly better than ECT. Out of 20 patients 17 preferred ECM to ECT (P less than 0.00036). ECM preparations should allow more satisfactory dietary management of patients with cystic fibrosis with longterm beneficial effect.

  10. Studies on the preparation and plasma spherodization of yttrium aluminosilicate glass microspheres for their potential application in liver brachytherapy

    NASA Astrophysics Data System (ADS)

    Sreekumar, K. P.; Saxena, S. K.; Kumar, Yogendra; Thiyagarajan, T. K.; Dash, Ashutosh; Ananthapadmanabhan, P. V.; Venkatesh, Meera

    2010-02-01

    Plasma spheroidization exploits the high temperature and high enthalpy available in the thermal plasma jet to melt irregularly shaped powder particles and quench them to get dense spherical particles. Plasma spheroidization is a versatile process and can be applied to metals, ceramics, alloys and composites to obtain fine spherical powders. Radioactive microspheres incorporated with high energetic beta emitting radioisotopes have been reported to be useful in the palliative treatment of liver cancer. These powders are to be prepared in closer range of near spherical morphology in the size range 20-35 microns. Inactive glass samples were prepared by heating the pre-calculated amount of glass forming ingredients in a recrystallized alumina crucible. The glass was formed by keeping the glass forming ingredients at 1700°C for a period of three hours to form a homogeneous melt. After cooling, the glass was recovered from the crucible by crushing and was subsequently powdered mechanically with the help of mortar and pestle. This powder was used as the feed stock for plasma spheroidization using an indigenously developed 40 kW plasma spray system. Experiments were carried out at various operating parameters. The operating parameters were optimised to get spheroidised particles. The powder was sieved to get the required size range before irradiation.

  11. Preparation of magnetic core-shell iron oxide@silica@nickel-ethylene glycol microspheres for highly efficient sorption of uranium(VI).

    PubMed

    Tan, Lichao; Zhang, Xiaofei; Liu, Qi; Wang, Jun; Sun, Yanbo; Jing, Xiaoyan; Liu, Jingyuan; Song, Dalei; Liu, Lianhe

    2015-04-21

    We report a facile approach for the formation of magnetic core-shell iron oxide@silica@nickel-ethylene glycol (Fe3O4@SiO2@Ni-L) microspheres. The structure and morphology of Fe3O4@SiO2@Ni-L are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and nitrogen sorption isotherm. The composite possesses a high specific surface area of 382 m(2) g(-1). The obtained core/shell structure is composed of a superparamagnetic core with a strong response to external fields, which are recovered readily from aqueous solutions by magnetic separation. When used as the adsorbent for uranium(vi) in water, the as-prepared Fe3O4@SiO2@Ni-L multi-structural microspheres exhibit a high adsorption capacity, which is mainly attributed to the large specific surface area and typical mesoporous characteristics of Fe3O4@SiO2@Ni-L microspheres. This work provides a promising approach for the design and synthesis of multifunctional microspheres, which can be used for water treatment, as well as having other potential applications in a variety of biomedical fields including drug delivery and biosensors.

  12. Large-scale preparation of strawberry-like, AgNP-doped SiO2 microspheres using the electrospraying method

    NASA Astrophysics Data System (ADS)

    Ma, Zhijun; Ji, Huijiao; Tan, Dezhi; Dong, Guoping; Teng, Yu; Zhou, Jiajia; Guan, Miaojia; Qiu, Jianrong; Zhang, Ming

    2011-07-01

    In this paper, we report on a novel strategy for the preparation of silver nanoparticle-doped SiO2 microspheres (Ag-SMSs) with an interesting strawberry-like morphology using a simple and efficient electrospraying method. SEM (scanning electron microscopy), TEM (transmission electron microscopy), XRD (x-ray diffraction), EDS (energy-dispersive spectroscopy) and UV-vis spectra (ultraviolet-visible spectra) were applied to investigate the morphology, structure, composition and optical properties of the hybrid microspheres, and E. coli (Escherichia coli) was used as a model microbe to evaluate their antibacterial ability. The results showed that the Ag-SMSs were environmentally stable and washing resistant. The Ag-SMSs exhibited effective inhibition against proliferation of E. coli, and their antibacterial ability could be well preserved for a long time. The environmental stability, washing resistance, efficient antibacterial ability and simple but productive preparation method endowed the Ag-SMSs with great potential for practical biomedical applications.

  13. A facile and cheap coating method to prepare SiO2/melamine-formaldehyde and SiO2/urea-formaldehyde composite microspheres

    NASA Astrophysics Data System (ADS)

    Mou, Shaoyan; Lu, Yao; Jiang, Yong

    2016-10-01

    A facile and cheap coating route has been explored to prepare SiO2/melamine formaldehyde hybrid particles. In this process, SiO2 microspheres act as seeds, and a polycondensation reaction occurs on the surface of melamine-formaldehyde pre-polymers. Formaldehyde is essential in this coating process because it acts as a novel and cheap surface modification agent instead of a traditional silane coupling agent. Ultrasonic method is used in the synthesis to avoid aggregation of nano- and micro-particles. Most of the traditional methods preparing composite microspheres were implemented under difficult conditions and at high costs. The improved coating method is much more able to provide a convenient path for researchers and engineers to more easily and economically perform experiments and engage in manufacturing. To verify this convenient method, SiO2/urea-formaldehyde composite microspheres were also prepared. SEM images show that the surfaces of all the products are smooth and well-shaped.

  14. 21 CFR 184.1187 - Calcium alginate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... alginic acid, a natural polyuronide constituent of certain brown algae. Calcium alginate is prepared by... Do. Fats and oils, § 170.3(n)(12) of this chapter 0.5 Do. Gelatins, puddings, § 170.3(n)(22) of...

  15. In vitro Evaluation of Novel Sustained Release Microspheres of Glipizide Prepared by the Emulsion Solvent Diffusion-Evaporation Method

    PubMed Central

    Phutane, P; Shidhaye, S; Lotlikar, V; Ghule, A; Sutar, S; Kadam, V

    2010-01-01

    The objective of the current investigation is to reduce dosing frequency and improve patient compliance by designing and systematically evaluating sustained release microspheres of Glipizide. An anti-diabetic drug, Glipizide, is delivered through the microparticulate system using ethyl cellulose as the controlled release polymer. Microspheres were developed by the emulsion solvent diffusion-evaporation technique by using the modified ethanol,-dichloromethane co-solvent system. The polymer mixture of ethyl cellulose and Eudragit® S100 was used in different ratios (1:0, 1:1, 2:3, 1:4 and 0:1) to formulate batches F1 to F5. The resulting microspheres were evaluated for particle size, densities, flow properties, morphology, recovery yield, drug content, and in vitro drug release behavior. The formulated microspheres were discrete, spherical with relatively smooth surface, and with good flow properties. Among different formulations, the fabricated microspheres of batch F3 had shown the optimum percent drug encapsulation of microspheres and the sustained release of the Glipizide for about 12 h. Release pattern of Glipizide from microspheres of batch F3 followed Korsmeyers-peppas model and zero-order release kinetic model. The value of ‘n’ was found to be 0.960, which indicates that the drug release was followed by anomalous (non-fickian) diffusion. The data obtained thus suggest that a microparticulate system can be successfully designed for sustained delivery of Glipizide and to improve dosage form characteristics for easy formulation. PMID:21331188

  16. Preparation and Characterization of 45S5 Bioactive Glass-based Scaffolds Loaded with PHBV Microspheres with Daidzein Release Function.

    PubMed

    Macías-Andrés, Víctor I; Li, Wei; Aguilar-Reyes, Ena A; Ding, Yaping; Roether, Judith A; Harhaus, Leila; León-Patiño, Carlos A; Boccaccini, A R

    2017-02-27

    PHBV microsphere loaded 45S5 bioactive glass (BG) based scaffolds with drug releasing capability have been developed. PHBV microspheres with a mean particle size 4 ± 2 μm loaded with daidzein were obtained by oil-in-water single emulsion solvent evaporation method and applied to the surface of BG scaffolds by dip coating technique. The morphology, in vitro bioactivity in simulated body fluid (SBF), mechanical properties and drug release kinetics of microsphere loaded scaffolds were studied. The microspheres were shown to be homogeneously dispersed on the scaffold surfaces. It was confirmed that hydroxyapatite crystals homogeneously grew not only on the surface of the scaffold but also on the surface of the microspheres within 3 days of immersion in SBF. The daidzein release from the microsphere loaded scaffolds lasted almost 1 month and was determined to be diffusion controlled. The microsphere loaded BG scaffolds with daidzein releasing capability obtained in this study are a candidate for bone tissue engineering. This article is protected by copyright. All rights reserved.

  17. Characterization of structure, physico-chemical properties and diffusion behavior of Ca-Alginate gel beads prepared by different gelation methods.

    PubMed

    Puguan, John Marc C; Yu, Xiaohong; Kim, Hern

    2014-10-15

    Ca-Alginate beads were prepared with either external or internal calcium sources by dripping technique. It was found that beads synthesized with internal calcium source had a looser structure and bigger pore size than those produced with external calcium source. Consequently, a faster diffusion rate of Vitamin B12 (VB12) within the beads with an internal calcium source was observed. Furthermore, the concentration of calcium ion, ionic strength and pH of the external gel beads formation solution were investigated. Results showed that (a) the concentration of the calcium ion was found to be the determining factor in the gel formation phenomenon; (b) the weight and volume losses are in effect due to water removal; (c) NaCl acts as a competitor with calcium and a screen in the electrostatic repulsion; and (d) the pH controls the gel formation process by regulating the dissociation of alginate and the complexation of the calcium cations. These results are keys to understanding the behavior and performance of beads in their utilization medium.

  18. Preparation of carbon microspheres decorated with silver nanoparticles and their ability to remove dyes from aqueous solution.

    PubMed

    Chen, Qingchun; Wu, Qingsheng

    2015-01-01

    Solid, but not hollow or porous, carbon microspheres decorated with silver nanoparticles (AgNP-CMSs) were prepared from silver nitrate and CMSs by a redox reaction at room temperature. The CMSs and AgNP-CMSs were characterized using X-ray diffraction, scanning electron microscopy, field emission scanning electron microscopy, Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR), and UV-vis spectrophotometry. Though with non-high specific surface area, the AgNP-CMSs exhibited a high adsorption capacity toward methylene blue (MB) in an aqueous solution. The AgNP-CMSs were able to remove all the MB from a solution of 30 mg/L MB in water within 1 min when the adsorbent concentration was 0.12 g/L. The AgNP-CMSs also exhibited good adsorption and photocatalytic activity in the decomposition of aqueous Rhodamine B as well as MB under visible light. FTIR was used to examine the interaction between AgNP-CMSs and MB, and the spectrum and more extra experiments suggest ionic interactions between cationic dyes and the negatively charged groups can be formed but not the presence of abundant π-π conjugations between dye molecules and the aromatic rings. The origin of the photocatalytic activity of AgNP-CMSs was attributed to a surface plasmon resonance (SPR) effect of the silver nanoparticles on the CMSs.

  19. Controlled microfluidic production of alginate beads for in situ encapsulation of microbes

    SciTech Connect

    Kalyanaraman, Meenaa; Retterer, Scott T; McKnight, Timothy E; Ericson, Milton Nance; Allman, Steve L; Elkins, James G; Palumbo, Anthony Vito; Keller, Martin; Doktycz, Mitchel John

    2009-01-01

    The development and refinement of a microfluidic-based alginate bead generator system for bacterial encapsulation is presented. The resulting microgels have application for the encapsulation of single cells, and can allow for small scale, clonal expansion of thousands of isolated cells in parallel. PDMS based microfluidic chips were fabricated using conventional lithography techniques to produce both externally gelled and directly gelled alginate microspheres using a controlled, water-in-oil emulsion system. The production of directly gelled beads, formed by the in-chip mixing of aqueous alginate and calcium chloride solutions dispersed within an organic carrier flowstream is qualitatively compared to a system, which produces beads and relies on diffusion of a crosslinking agent from the carrier fluid to cause gelation (external gelation). While the direct gelation scheme allows the use of biocompatible oils as the organic carrier, it also has a detrimental effect on device stability often resulting in clogging and gel-streaming at the microfluidic interface of these solutions. A design for the continuous production of directly gelled beads was evaluated in terms of the threshold flow conditions and reagent concentrations that did not result in clogging or streaming. Monodisperse alginate microgels of 30 mum diameter were produced at frequencies of over 500 beads per second. The beads could be completely dispersed into aqueous media using an off-chip washing protocol to remove the organic phase. The microgels effectively encapsulated individual or small numbers of GFP-expressing Escherichia. coli, which could be subsequently clonally expanded. The described microfluidic platform is a robust front-end sample preparation technology that shows strong potential for use in drug delivery systems, biosensors, and other cell-based microcompartmentalization applications. The co-culturing of microbial colonies in a large population of alginate beads will allow for functional

  20. The preparation of composite microsphere with hollow core/porous shell structure by self-assembling of latex particles at emulsion droplet interface.

    PubMed

    He, Xiao Dong; Ge, Xue Wu; Wang, Mo Zhen; Zhang, Zhi Cheng

    2006-07-15

    A submicrometer-scaled polystyrene/melamine-formaldehyde hollow microsphere composite was prepared by self-assembling of sulfonated polystyrene (SPS) latex particles at the interface of emulsion droplets and then being fixed in place using a hard melamine-formaldehyde (MF) composite layer. For control-released purposes, the influential factors that control the size and uniformity of the packed-droplets and the permeability of the composite shell, including the initial particle location, the hydrophilicity and the size of colloidal templates, the oil phase solvent and reserving time of emulsions after the addition of MF prepolymer, were further studied. Relatively uniform sized particle packed-droplets with an average diameter of 10 microm were obtained. The assembled SPS particles kept ordering and minimal conglutination after the preparation of composite microspheres, which allows of controlling the permeability from the interstices between the particles. Porous-mesh-structured MF composite layer was formed to further control the permeability. The morphology of emulsions and composite microspheres were characterized by optical microscopy, scanning and transmission electron microscopy.

  1. Engineering alginate as bioink for bioprinting

    PubMed Central

    Jia, Jia; Richards, Dylan J.; Pollard, Samuel; Tan, Yu; Rodriguez, Joshua; Visconti, Richard P.; Trusk, Thomas C.; Yost, Michael J.; Yao, Hai; Markwald, Roger R.; Mei, Ying

    2015-01-01

    Recent advances in 3D printing offer an excellent opportunity to address critical challenges faced by current tissue engineering approaches. Alginate hydrogels have been extensively utilized as bioinks for 3D bioprinting. However, most previous research has focused on native alginates with limited degradation. The application of oxidized alginates with controlled degradation in bioprinting has not been explored. Here, we prepared a collection of 30 different alginate hydrogels with varied oxidation percentages and concentrations to develop a bioink platform that can be applied to a multitude of tissue engineering applications. We systematically investigated the effects of two key material properties (i.e. viscosity and density) of alginate solutions on their printabilities to identify a suitable range of material properties of alginates to be applied to bioprinting. Further, four alginate solutions with varied biodegradability were printed with human adipose-derived stem cells (hADSCs) into lattice-structured, cell-laden hydrogels with high accuracy. Notably, these alginate-based bioinks were shown to be capable of modulating proliferation and spreading of hADSCs without affecting structure integrity of the lattice structures (except the highly degradable one) after 8 days in culture. This research lays a foundation for the development of alginate-based bioink for tissue-specific tissue engineering applications. PMID:24998183

  2. Engineering alginate as bioink for bioprinting.

    PubMed

    Jia, Jia; Richards, Dylan J; Pollard, Samuel; Tan, Yu; Rodriguez, Joshua; Visconti, Richard P; Trusk, Thomas C; Yost, Michael J; Yao, Hai; Markwald, Roger R; Mei, Ying

    2014-10-01

    Recent advances in three-dimensional (3-D) printing offer an excellent opportunity to address critical challenges faced by current tissue engineering approaches. Alginate hydrogels have been used extensively as bioinks for 3-D bioprinting. However, most previous research has focused on native alginates with limited degradation. The application of oxidized alginates with controlled degradation in bioprinting has not been explored. Here, a collection of 30 different alginate hydrogels with varied oxidation percentages and concentrations was prepared to develop a bioink platform that can be applied to a multitude of tissue engineering applications. The authors systematically investigated the effects of two key material properties (i.e. viscosity and density) of alginate solutions on their printabilities to identify a suitable range of material properties of alginates to be applied to bioprinting. Further, four alginate solutions with varied biodegradability were printed with human adipose-derived stem cells (hADSCs) into lattice-structured, cell-laden hydrogels with high accuracy. Notably, these alginate-based bioinks were shown to be capable of modulating proliferation and spreading of hADSCs without affecting the structure integrity of the lattice structures (except the highly degradable one) after 8days in culture. This research lays a foundation for the development of alginate-based bioink for tissue-specific tissue engineering applications.

  3. Preparation of nano/macroporous polycaprolactone microspheres for an injectable cell delivery system using room temperature ionic liquid and camphene.

    PubMed

    Kim, Seong Yeol; Hwang, Ji-Young; Shin, Ueon Sang

    2016-03-01

    The nano/macroporous polycaprolactone (PCL) microspheres with cell active surfaces were developed as an injectable cell delivery system. Room temperature ionic liquid (RTIL) and camphene were used as a liquid mold and a porogen, respectively. Various-sized spheres of 244-601μm with pores of various size and shape of 0.02-100μm, were formed depending on the camphene/RTIL ratio (0.8-2.6). To give cell activity, the surface of porous microspheres were further modified with nerve growth factors (NGF) containing gelatin to give a thin NGF/gelatin layer, to which the neural progenitor cells (PC-12) attached and extended their neurites on to the surface layers of the microspheres. The developed microspheres may be potentially applicable as a neuronal cell delivery scaffold for neuron tissue engineering.

  4. Protective effects of alginate-chitosan microspheres loaded with alkaloids from Coptis chinensis Franch. and Evodia rutaecarpa (Juss.) Benth. (Zuojin Pill) against ethanol-induced acute gastric mucosal injury in rats.

    PubMed

    Wang, Qiang-Song; Zhu, Xiao-Ning; Jiang, Heng-Li; Wang, Gui-Fang; Cui, Yuan-Lu

    2015-01-01

    Zuojin Pill (ZJP), a traditional Chinese medicine formula, consists of Coptis chinensis Franch. and Evodia rutaecarpa (Juss.) Benth. in a ratio of 6:1 (w/w) and was first recorded in "Danxi's experiential therapy" for treating gastrointestinal disorders in the 15th century. However, the poor solubility of alkaloids from ZJP restricted the protective effect in treating gastritis and gastric ulcer. The aim of the study was to investigate the protective mechanism of mucoadhesive microspheres loaded with alkaloids from C. chinensis Franch. and E. rutaecarpa (Juss.) Benth. on ethanol-induced acute gastric mucosal injury in rats. Surface morphology, particle size, drug loading, encapsulation efficiency, in vitro drug release, mucoadhesiveness, and fluorescent imaging of the microspheres in gastrointestinal tract were studied. The results showed that the mucoadhesive microspheres loaded with alkaloids could sustain the release of drugs beyond 12 hours and had gastric mucoadhesive property with 82.63% retention rate in vitro. The fluorescence tracer indicated high retention of mucoadhesive microspheres within 12 hours in vivo. The mucoadhesive microspheres loaded with alkaloids could reduce the gastric injury by decreasing the mucosal lesion index, increasing the percentage of inhibition and increasing the amount of mucus in the gastric mucosa in an ethanol-induced gastric mucosal injury rat model. Moreover, the mucoadhesive microspheres loaded with alkaloids reduce the inflammatory response by decreasing the levels of tumor necrosis factor-α (TNF-α), interleukin 1β (IL-1β), downregulating the mRNA expression of inducible nitric oxide synthase, TNF-α, and IL-1β in gastric mucosa. All the results indicate that mucoadhesive microspheres loaded with alkaloids could not only increase the residence time of alkaloids in rat stomach, but also exert gastroprotective effects through reducing the inflammatory response on ethanol-induced gastric mucosal damage. Thus, these

  5. Preparation and biological characteristics of recombinant human bone morphogenetic protein-2-loaded dextran-co-gelatin hydrogel microspheres, in vitro and in vivo studies.

    PubMed

    Chen, Faming; Wu, Zhifen; Wang, Qintao; Wu, Hong; Zhang, Yongjie; Nie, Xin; Jin, Yan

    2005-11-01

    Hydrogels are based on hydrophilic polymers which are cross-linked to prevent dissolution in water. Because hydrogels can contain large amounts of water, they are interesting devices for the delivery of protein drugs. In this contribution, biodegradable dextran-co-gelatin hydrogel microspheres (DG-MPs) are described which are based on physical interactions and are particularly suitable for the controlled delivery of pharmaceutically active proteins. The unique feature of this preparation system is that the hydrogel microsphere formation takes place in an all-aqueous solution, by which the use of organic solvents is avoided. We investigated the preparation and biological activities of recombinant human bone morphogenetic protein-2 (rhBMP2)-loaded dextran-co-gelatin hydrogel microspheres (rhBMP2-DG-MPs), which aimed to keep rhBMP2's biological activity and to achieve a long-term sustained release of rhBMP2. The microspheres' average diameter was about 20-40 microm and rhBMP2 release in vitro could be maintained for >10 days. Cytology studies showed that using rhBMP2-DG-MPs could promote the proliferation and osteoblastic differentiation of periodontal ligament cells better than using rhBMP2 aqueous solution. By a freeze-drying method, rhBMP2-DG-MPs could be adhered in chitosan membranes for guided tissue regeneration use, namely functionalized membranes. To evaluate bone regeneration induced by rhBMP2-DG-MPs, an animal experiment with canine class III furcation defects was adopted and the results indicated that using rhBMP2-DG-MPs incorporating scaffolds and functionalized membranes could gain more periodontal tissue regeneration than using scaffolds and general membranes soaked with concentrated rhBMP2 aqueous solution. Therefore, those studies demonstrate the potential of DG-MPs in the sustained delivery of low dosages of rhBMP2 to periodontal defects.

  6. Facile preparation of hexadecyl-functionalized magnetic core-shell microsphere for the extraction of polychlorinated biphenyls in environmental waters.

    PubMed

    Fan, Yu-Han; Zhang, Shou-Wen; Qin, Shi-Bin; Li, Xiao-Shui; Zhang, Yuan; Qi, Shi-Hua

    2017-03-10

    Alkyl moieties which can retain target analytes due to their lipophilicity are important in sample preparation. In this work, hexadecyl-functionalized magnetic core-shell microspheres (Fe3O4@SiO2-C16) was successfully prepared by one-pot sol-gel method and used for magnetic solid-phase extraction of polychlorinated biphenyls (PCBs) in environmental water samples. Optimized preparation method was achieved by altering the adding moment of hexadecyl-silane. The resultant materials were systematically characterized by scanning electron microscope, transmission electron microscope, Fourier transform infrared spectroscopy, energy dispersive X-ray spectrometry, tensionmeter, and vibrating sample magnetometer. The results demonstrated that the optimized adsorbent exhibited core-shell structure, superparamagnetic (66 emu/g), and extremely hydrophobic (water contact angle of 122°) properties. To evaluate the extraction performance, the prepared material coupled with gas chromatography-triple quadrupole mass spectrometry (GC-MS/MS) was applied to determinate PCBs. The extraction conditions were optimized. Under the optimal conditions, the proposed method showed a good linearity range of 1-100 ng L(-1) with correlation coefficients (R) of 0.9989-0.9993. Based on a signal-to-noise ratio of 3 and 10, the limits of detection (LODs) and limits of quantification (LOQs) were in the range 0.14-0.27 and 0.39-0.91 ng L(-1), respectively. The intra- and inter-day relative standard deviations (RSDs) were less than 9.06%. The absolute recoveries of PCBs in spiked real water samples were in the range of 75.17 to 101.20%. Additionally, reusability and batch-to-batch reproducibility of the resultant material were acceptable with RSDs less than 5.64 and 3.25%, respectively. Graphical Abstract The synthesis procedure of Fe3O4@SiO2-C16 and determination of PCBs in water sample 129 × 50 mm (300 × 300 DPI).

  7. Preparation, Modification, and Characterization of Alginate Hydrogel with Nano-/Microfibers: A New Perspective for Tissue Engineering

    PubMed Central

    Palma Santana, Bianca; Piva, Evandro; Varella de Carvalho, Rodrigo; Fernando Demarco, Flávio; Lenin Villarreal Carreño, Neftali

    2013-01-01

    We aimed to develop an alginate hydrogel (AH) modified with nano-/microfibers of titanium dioxide (nfTD) and hydroxyapatite (nfHY) and evaluated its biological and chemical properties. Nano-/microfibers of nfTD and nfHY were combined with AH, and its chemical properties were evaluated by FTIR spectroscopy, X-ray diffraction, energy dispersive X-Ray analysis, and the cytocompatibility by the WST-1 assay. The results demonstrate that the association of nfTD and nfHY nano-/microfibers to AH did not modified the chemical characteristics of the scaffold and that the association was not cytotoxic. In the first 3 h of culture with NIH/3T3 cells nfHY AH scaffolds showed a slight increase in cell viability when compared to AH alone or associated with nfTD. However, an increase in cell viability was observed in 24 h when nfTD was associated with AH scaffold. In conclusion our study demonstrates that the combination of nfHY and nfTD nano-/microfibers in AH scaffold maintains the chemical characteristics of alginate and that this association is cytocompatible. Additionally the combination of nfHY with AH favored cell viability in a short term, and the addition of nfTD increased cell viability in a long term. PMID:23862142

  8. Modeling competitive sorption of lead and copper ions onto alginate and greenly prepared algal-based beads.

    PubMed

    Wang, Shengye; Vincent, Thierry; Faur, Catherine; Guibal, Eric

    2017-05-01

    The binary sorption of Pb(II) and Cu(II) onto calcium alginate, algal biomass and algal/glutaraldehyde-crosslinked polyethyleneimine (PEI) composite beads was studied in the absence and presence of Ca(II). Different competitive models were compared for predicting the equilibrium data. Results show that all the sorbents have a significant preference for Pb(II) over Cu(II) in Pb-Cu system: the separation factors reach 14.1, 9.1 and 3.6 for alginate, algal biomass and algal/PEI beads, respectively. Kinetic studies confirm the occurrence of an ion-exchange mechanism between Pb(II) and Cu(II) as the sorption sites are progressively saturated. Competitive Sips model predicts well the sorption data for all the sorbents. In Pb-Cu-Ca system, the Cu(II) sorption by algal beads was negligible, while algal/PEI still maintained a significant sorption of Cu(II) sorption under these conditions.

  9. Preparation of porous yttrium oxide microparticles by gelation of ammonium alginate in aqueous solution containing yttrium ions.

    PubMed

    Kawashita, Masakazu; Matsui, Naoko; Li, Zhixia; Miyazaki, Toshiki

    2010-06-01

    Porous Y2O3 microparticles 500 microm in size were obtained, when 1 wt%-ammonium alginate aqueous solution was dropped into 0.5 M-YCl3 aqueous solution by a Pasteur pipette and the resultant gel microparticles were heat-treated at 1100 degrees C. Small pores less than 1 microm were formed in the microparticles by the heat treatment. The bulk density of the heat-treated microparticle was as low as 0.66 g cm(-3). The chemical durability of the heat-treated microparticles in simulated body fluid at pH = 6 and 7 was high enough for clinical application of in situ radiotherapy. Although the size of the microparticles should be decreased to around 25 microm using atomizing device such as spray gun for clinical application, we found that the porous Y2O3 microparticles with high chemical durability and low density can be obtained by utilizing gelation of ammonium alginate in YCl3 aqueous solution in this study.

  10. Preparation of thermoresponsive Fe3O4/P(acrylic acid-methyl methacrylate-N-isopropylacrylamide) magnetic composite microspheres with controlled shell thickness and its releasing property for phenolphthalein.

    PubMed

    Zhang, Baoliang; Zhang, Hepeng; Fan, Xinlong; Li, Xiangjie; Yin, Dezhong; Zhang, Qiuyu

    2013-05-15

    In this work, Fe3O4/P(acrylic acid-methyl methacrylate-N-isopropylacrylamide) (Fe3O4/P(AA-MMA-NIPAm)) thermoresponsive magnetic composite microspheres have been prepared by controlled radical polymerization in the presence of 1,1-diphenylethene (DPE). The shell thickness of thermosensitive polymer (PNIPAm), which was on the surface of the microspheres, can be controlled by using DPE method. The morphology and thermosensitive properties of the composite microspheres, polymerization mechanism of the shell were characterized by TEM, FTIR, VSM, Laser Particle Sizer, TGA, NMR, and GPC. The microspheres with narrow particle size distribution show high saturation magnetization and superparamagnetism. The thermosensitive properties of the composite microspheres can be adjusted indirectly via controlling the addition amount of monomer (NIPAm) in the second step during controlled radical polymerization. Phenolphthalein was chosen as a model drug to investigate drug release behavior of the thermoresponsive magnetic composite microspheres with different shell thickness. Controlled drug release testing reveals that the release behavior depends on the thickness of polymer on the surface of the microspheres.

  11. Electrochemical properties of tungsten sulfide–carbon composite microspheres prepared by spray pyrolysis

    PubMed Central

    Choi, Seung Ho; Boo, Sung Jin; Lee, Jong-Heun; Kang, Yun Chan

    2014-01-01

    Tungsten sulfide (WS2)–carbon composite powders with superior electrochemical properties are prepared by a two-step process. WO3-carbon composite powders were first prepared by conventional spray pyrolysis, and they were then sulfidated to form WS2-carbon powders. Bare WS2 powders are also prepared by sulfidation of bare WO3 powders obtained by spray pyrolysis. Stacked graphitic layers could not be found in the bare WS2 and WS2–carbon composite powders. The amorphous bare WS2 and WS2–carbon composite powders have Brunauer–Emmett–Teller (BET) surface areas of 2.8 and 4 m2 g−1, respectively. The initial discharge and charge capacities of the WS2–carbon composite powders at a current density of 100 mA g−1 are 1055 and 714 mA h g−1, respectively, and the corresponding initial Coulombic efficiency is 68%. On the other hand, the initial discharge and charge capacities of the bare WS2 powders are 514 and 346 mA h g−1, respectively. The discharge capacities of the WS2–carbon composite powders for the 2nd and 50th cycles are 716 and 555 mA h g−1, respectively, and the corresponding capacity retention measured after first cycle is 78%. PMID:25169439

  12. MRI visible drug eluting magnetic microspheres for transcatheter intra-arterial delivery to liver tumors.

    PubMed

    Kim, Dong-Hyun; Chen, Jeane; Omary, Reed A; Larson, Andrew C

    2015-01-01

    Magnetic resonance imaging (MRI)-visible amonafide-eluting alginate microspheres were developed for targeted arterial-infusion chemotherapy. These alginate microspheres were synthesized using a highly efficient microfluidic gelation process. The microspheres included magnetic clusters formed by USPIO nanoparticles to permit MRI and a sustained drug-release profile. The biocompatibility, MR imaging properties and amonafide release kinetics of these microspheres were investigated during in vitro studies. A xenograft rodent model was used to demonstrate the feasibility to deliver these microspheres to liver tumors using hepatic transcatheter intra-arterial infusions and potential to visualize the intra-hepatic delivery of these microspheres to both liver tumor and normal tissues with MRI immediately after infusion. This approach offer the potential for catheter-directed drug delivery to liver tumors for reduced systemic toxicity and superior therapeutic outcomes.

  13. MRI Visible Drug Eluting Magnetic Microspheres for Transcatheter Intra-Arterial Delivery to Liver Tumors

    PubMed Central

    Kim, Dong-Hyun; Chen, Jeane; Omary, Reed A.; Larson, Andrew C.

    2015-01-01

    Magnetic resonance imaging (MRI)-visible amonafide-eluting alginate microspheres were developed for targeted arterial-infusion chemotherapy. These alginate microspheres were synthesized using a highly efficient microfluidic gelation process. The microspheres included magnetic clusters formed by USPIO nanoparticles to permit MRI and a sustained drug-release profile. The biocompatibility, MR imaging properties and amonafide release kinetics of these microspheres were investigated during in vitro studies. A xenograft rodent model was used to demonstrate the feasibility to deliver these microspheres to liver tumors using hepatic transcatheter intra-arterial infusions and potential to visualize the intra-hepatic delivery of these microspheres to both liver tumor and normal tissues with MRI immediately after infusion. This approach offer the potential for catheter-directed drug delivery to liver tumors for reduced systemic toxicity and superior therapeutic outcomes. PMID:25767615

  14. Encapsulation of probiotic Bifidobacterium longum BIOMA 5920 with alginate-human-like collagen and evaluation of survival in simulated gastrointestinal conditions.

    PubMed

    Su, Ran; Zhu, Xiao-Li; Fan, Dai-Di; Mi, Yu; Yang, Chan-Yuan; Jia, Xin

    2011-12-01

    Alginate (ALg)-human-like collagen (HLC) microspheres were prepared by the technology of electrostatic droplet generation in order to develop a biocompatible vehicle for probiotic bacteria. Microparticles were spherical with mean particle size of 400μm. The encapsulation efficiency (EE) of ALg-HLC microspheres could reach 92-99.2%. Water-soluble and fibrous human-like collagen is combined with sodium alginate through intermolecular hydrogen bonding and electrostatic force which were investigated by Fourier transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC), thus the matrix of ALg-HLC was very stable. Bifidobacterium longum BIOMA 5920, as a kind of probiotic bacteria, was encapsulated with alginate-human-like collagen to survive and function in simulated gastrointestinal juice. Microparticles were very easy to degradation in simulated intestinal juices. After incubation in simulated gastric (pH 2.0, 2h), the encapsulated B. longum BIOMA 5920 numbers were 4.81 ± 0.38 log cfu/g.

  15. Preparation and in vitro characterization of dexamethasone-loaded poly(D,L-lactic acid) microspheres embedded in poly(ethylene glycol)-poly({varepsilon}-caprolactone)-poly(ethylene glycol) hydrogel for orthopedic tissue engineering.

    PubMed

    Fan, Min; Guo, QingFa; Luo, JingCong; Luo, Feng; Xie, Ping; Tang, XiaoHai; Qian, ZhiYong

    2013-08-01

    The corium is decreased to about half of its thickness in skin defects and wrinkles due to gravity and environment. In this study, dexamethasone/poly(d,l-lactic acid) (Mn = 160,000) microspheres were incorporated into poly(ethylene glycol)-poly(ε-caprolactone)-poly(ethylene glycol) (Mn = 3300) hydrogel to prepare an injectable hydrogel composite. The composite was designed to increase the thickness of the corium. Dexamethasone/poly(d,l-lactic acid) microspheres were prepared by oil-in-water emulsion/solvent evaporation technique. The properties of microspheres were investigated by size distribution measurement, scanning electron microscope and x-ray diffraction. Drug loading, encapsulation efficiency, and drug delivery behavior of microspheres were also studied in detail. Cell adhesion of microspheres was investigated by NIH3T3 cell in vitro. The properties of hydrogel composite were investigated by scanning electron microscope, rheological measurements and methyl thiazolyl tetrazolium assay. Drug release from composite was determined by HPLC-UV analysis. These results suggested that poly(d,l-lactic acid) microspheres encapsulating dexamethasone embedded in poly(ethylene glycol)-poly(ε-caprolactone)-poly(ethylene glycol) hydrogel might have prospective application in orthopedic tissue engineering field.

  16. Role of Calcium Alginate and Mannitol in Protecting Bifidobacterium

    PubMed Central

    Dianawati, Dianawati; Mishra, Vijay

    2012-01-01

    Fourier transform infrared (FTIR) spectroscopy was carried out to ascertain the mechanism of Ca-alginate and mannitol protection of cell envelope components and secondary proteins of Bifidobacterium animalis subsp. lactis Bb12 after freeze-drying and after 10 weeks of storage at room temperature (25°C) at low water activities (aw) of 0.07, 0.1, and 0.2. Preparation of Ca-alginate and Ca-alginate-mannitol as microencapsulants was carried out by dropping an alginate or alginate-mannitol emulsion containing bacteria using a burette into CaCl2 solution to obtain Ca-alginate beads and Ca-alginate-mannitol beads, respectively. The wet beads were then freeze-dried. The aw of freeze-dried beads was then adjusted to 0.07, 0.1, and 0.2 using saturated salt solutions; controls were prepared by keeping Ca-alginate and Ca-alginate-mannitol in aluminum foil without aw adjustment. Mannitol in the Ca-alginate system interacted with cell envelopes during freeze-drying and during storage at low aws. In contrast, Ca-alginate protected cell envelopes after freeze-drying but not during 10-week storage. Unlike Ca-alginate, Ca-alginate-mannitol was effective in retarding the changes in secondary proteins during freeze-drying and during 10 weeks of storage at low aws. It appears that Ca-alginate-mannitol is more effective than Ca-alginate in preserving cell envelopes and proteins after freeze-drying and after 10 weeks of storage at room temperature (25°C). PMID:22843535

  17. Preparation of hollow microsphere@onion-like solid nanosphere MoS2 coated by a carbon shell as a stable anode for optimized lithium storage

    NASA Astrophysics Data System (ADS)

    Guo, Bangjun; Yu, Ke; Song, Haili; Li, Honglin; Tan, Yinghua; Fu, Hao; Li, Chao; Lei, Xiang; Zhu, Ziqiang

    2015-12-01

    A one-step hydrothermal method was successfully used to fabricate hollow microsphere@onion-like solid nanosphere MoS2. Then the as-prepared sS-MoS2 was decorated with a carbon shell using dopamine as a carbon source by a facile route, resulting in hollow microsphere@onion-like solid nanosphere MoS2 decorated with carbon shell (sS-MoS2@C). A synergistic effect was observed for the two-component material, leading to new electrochemical processes for lithium storage, with improved electroconductivity and structural soundness, triggering an ascending capacity upon cycling. The as-prepared sS-MoS2@C exhibits optimized electrochemical behaviour with high specific capacity (1107 mA h g-1 at 100 mA g-1), superior high-rate capability (805 mA h g-1 at 5000 mA g-1) and good cycling stability (91.5% of capacity retained after 100 cycles), suggesting its potential application in high-energy lithium-ion batteries.A one-step hydrothermal method was successfully used to fabricate hollow microsphere@onion-like solid nanosphere MoS2. Then the as-prepared sS-MoS2 was decorated with a carbon shell using dopamine as a carbon source by a facile route, resulting in hollow microsphere@onion-like solid nanosphere MoS2 decorated with carbon shell (sS-MoS2@C). A synergistic effect was observed for the two-component material, leading to new electrochemical processes for lithium storage, with improved electroconductivity and structural soundness, triggering an ascending capacity upon cycling. The as-prepared sS-MoS2@C exhibits optimized electrochemical behaviour with high specific capacity (1107 mA h g-1 at 100 mA g-1), superior high-rate capability (805 mA h g-1 at 5000 mA g-1) and good cycling stability (91.5% of capacity retained after 100 cycles), suggesting its potential application in high-energy lithium-ion batteries. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr05595d

  18. Ion exchange in alginate gels--dynamic behaviour revealed by electron paramagnetic resonance.

    PubMed

    Ionita, Gabriela; Ariciu, Ana Maria; Smith, David K; Chechik, Victor

    2015-12-14

    The formation of alginate gel from low molecular weight alginate and very low molecular weight alginate in the presence of divalent cations was investigated using Electron Paramagnetic Resonance (EPR) spectroscopy. The transition from sol to gel in the presence of divalent cations was monitored by the changes in the dynamics of spin labelled alginate. The immobilisation of the spin labelled alginate in the gel reflects the strength of interaction between the cation and alginate chain. Diffusion experiments showed that both the cation and alginate polyanion in the gel fibres can exchange with molecules in solution. In particular, we showed that dissolved alginate polyanions can replace alginates in the gel fibres, which can hence diffuse through the bulk of the gel. This illustrates the surprisingly highly dynamic nature of these gels and opens up the possibility of preparing multicomponent alginate gels via polyanion exchange process.

  19. microsphere assemblies

    NASA Astrophysics Data System (ADS)

    Peña-Flores, Jesús I.; Palomec-Garfias, Abraham F.; Márquez-Beltrán, César; Sánchez-Mora, Enrique; Gómez-Barojas, Estela; Pérez-Rodríguez, Felipe

    2014-09-01

    The effect of Fe ion concentration on the morphological, structural, and optical properties of TiO2 films supported on silica (SiO2) opals has been studied. TiO2:Fe2O3 films were prepared by the sol-gel method in combination with a vertical dip coating procedure; precursor solutions of Ti and Fe were deposited on a monolayer of SiO2 opals previously deposited on a glass substrate by the same procedure. After the dip coating process has been carried out, the samples were thermally treated to obtain the TiO2:Fe2O3/SiO2 composites at the Fe ion concentrations of 1, 3, and 5 wt%. Scanning electron microscopy (SEM) micrographs show the formation of colloidal silica microspheres of about 50 nm diameter autoensembled in a hexagonal close-packed fashion. Although the X-ray diffractograms show no significant effect of Fe ion concentration on the crystal structure of TiO2, the μ-Raman and reflectance spectra do show that the intensity of a phonon vibration mode and the energy bandgap of TiO2 decrease as the Fe+3 ion concentration increases.

  20. Preparation of phenyl group-functionalized magnetic mesoporous silica microspheres for fast extraction and analysis of acetaldehyde in mainstream cigarette smoke by gas chromatography-mass spectrometry.

    PubMed

    Huang, Danni; Sha, Yunfei; Zheng, Saijing; Liu, Baizhan; Deng, Chunhui

    2013-10-15

    Acetaldehyde is regarded as a toxic mainstream cigarette smoke constituent, and measurement of acetaldehyde in complex real samples is difficult owing to its high volatility and reactivity. In this work, phenyl group-functionalized magnetic mesoporous microspheres were developed as the solid-phase extraction sorbents for enrichment and analysis of acetaldehyde in mainstream cigarette smoke. The functional magnetic microspheres were first synthesized through a facile one-pot co-condensation approach. The prepared nanomaterials possessed abundant silanol groups in the exterior surface and numerous phenyl groups in the interior pore-walls, as well as a large surface area (273.5m(2)/g), strong superparamagnetism and uniform mesopores (3.3 nm). Acetaldehyde in mainstream cigarette smoke was collected in water and derivatizated with O-2,3,4,5,6-(pentafluorobenzyl)hydroxylamine. The formed acetaldehyde oximes were extracted and enriched by the prepared adsorbents via π-π interactions and subsequently analyzed using GC-MS. Extraction conditions such as amounts of sorbents, eluting solvent, adsorption and desorption time were investigated and optimized to achieve the best efficiency. Method validations including linearity, recovery, repeatability, and limit of detection were also studied. It was found that the suggested methodology provided low detection limit of 0.04 mg/mL, good recovery of 88-92%, intra-day and inter-day RSD values of 4.5% and 10.1%, and linear range of 0.25-4 mg/mL (R(2)=0.999). The results indicated that the proposed method based on phenyl-functionalized magnetic mesoporous microspheres was rapid, efficient and convenient for the enrichment and analysis of acetaldehyde in tobacco.

  1. A quadruped study on chitosan microspheres containing atorvastatin calcium: preparation, characterization, quantification and in-vivo application.

    PubMed

    Eroglu, Hakan; Nemutlu, Emirhan; Turkoglu, Omer Faruk; Nacar, Osman; Bodur, Ebru; Sargon, Mustafa Fevzi; Beskonakli, Etem; Oner, Levent

    2010-09-01

    Atorvastatin is commonly used as a cholesterol lowering agent in patients. Recently, the neuroprotective effects of atorvastatin became the focus of many research studies. In this study, we have formulated chitosan microspheres containing atorvastatin calcium. In-vitro characterization of chitosan microspheres and quantification of atorvastatin calcium from formulations were also evaluated. The neuroprotective efficiency of atorvastatin calcium was investigated by an experimental spinal cord injury model. Atorvastatin calcium microspheres were implanted at the laminectomy area (1 mg/kg) immediately after trauma. Twenty-four hours after injury, motor functions of animals were scored according to modified Tarlov Scale. In spinal cord tissues tumor necrosis factor (TNF)-alpha, interleukin (IL)-1beta, IL-6 and lipid peroxidation levels were quantified and ultrastructural changes have been investigated. The results of all parameters indicate that microspheres containing atorvastatin calcium were capable of improving functional outcome, attenuating the expression of TNF-alpha, IL-1beta and IL-6; lowering lipid peroxidation levels and maintaining the preservation of the cellular uniformity.

  2. Optimization of preparation method for ketoprofen-loaded microspheres consisting polymeric blends using simplex lattice mixture design.

    PubMed

    Das, Sanjoy Kumar; Khanam, Jasmina; Nanda, Arunabha

    2016-12-01

    In the present investigation, simplex lattice mixture design was applied for formulation development and optimization of a controlled release dosage form of ketoprofen microspheres consisting polymers like ethylcellulose and Eudragit(®)RL 100; when those were formed by oil-in-oil emulsion solvent evaporation method. The investigation was carried out to observe the effects of polymer amount, stirring speed and emulsifier concentration (% w/w) on percentage yield, average particle size, drug entrapment efficiency and in vitro drug release in 8h from the microspheres. Analysis of variance (ANOVA) was used to estimate the significance of the models. Based on the desirability function approach numerical optimization was carried out. Optimized formulation (KTF-O) showed close match between actual and predicted responses with desirability factor 0.811. No adverse reaction between drug and polymers were observed on the basis of Fourier transform infrared (FTIR) spectroscopy and Differential scanning calorimetric (DSC) analysis. Scanning electron microscopy (SEM) was carried out to show discreteness of microspheres (149.2±1.25μm) and their surface conditions during pre and post dissolution operations. The drug release pattern from KTF-O was best explained by Korsmeyer-Peppas and Higuchi models. The batch of optimized microspheres were found with maximum entrapment (~90%), minimum loss (~10%) and prolonged drug release for 8h (91.25%) which may be considered as favourable criteria of controlled release dosage form.

  3. Relevance of rheological properties of sodium alginate in solution to calcium alginate gel properties.

    PubMed

    Fu, Shao; Thacker, Ankur; Sperger, Diana M; Boni, Riccardo L; Buckner, Ira S; Velankar, Sachin; Munson, Eric J; Block, Lawrence H

    2011-06-01

    The purpose of this study is to determine whether sodium alginate solutions' rheological parameters are meaningful relative to sodium alginate's use in the formulation of calcium alginate gels. Calcium alginate gels were prepared from six different grades of sodium alginate (FMC Biopolymer), one of which was available in ten batches. Cylindrical gel samples were prepared from each of the gels and subjected to compression to fracture on an Instron Universal Testing Machine, equipped with a 1-kN load cell, at a cross-head speed of 120 mm/min. Among the grades with similar % G, (grades 1, 3, and 4), there is a significant correlation between deformation work (L(E)) and apparent viscosity (η(app)). However, the results for the partial correlation analysis for all six grades of sodium alginate show that L(E) is significantly correlated with % G, but not with the rheological properties of the sodium alginate solutions. Studies of the ten batches of one grade of sodium alginate show that η(app) of their solutions did not correlate with L(E) while tan δ was significantly, but minimally, correlated to L(E). These results suggest that other factors--polydispersity and the randomness of guluronic acid sequencing--are likely to influence the mechanical properties of the resultant gels. In summary, the rheological properties of solutions for different grades of sodium alginate are not indicative of the resultant gel properties. Inter-batch differences in the rheological behavior for one specific grade of sodium alginate were insufficient to predict the corresponding calcium alginate gel's mechanical properties.

  4. Preparation and In Vitro Biological Evaluation of Octacalcium Phosphate/Bioactive Glass-Chitosan/ Alginate Composite Membranes Potential for Bone Guided Regeneration.

    PubMed

    Xu, Sanzhong; Chen, Xiaoyi; Yang, Xianyan; Zhang, Lei; Yang, Guojing; Shao, Huifeng; He, Yong; Gou, Zhongru

    2016-06-01

    The chitosan/alginate-trace element-codoped octacalcium phosphate/nano-sized bioactive glass (CS/ALG-teOCP/nBG) composite membranes were prepared by a layer-by-layer coating method for the functional requirement of guided bone regeneration (GBR). The morphology, mechanical properties and moisture content of the membranes was studied by scanning electron microscopy (SEM) observation, mechanical and swelling test. The results showed that the teOCP/nBG distributed uniformly in the composite membranes, and such as-prepared composite membrane exhibited an excellent tensile strength, accompanying with mechanical decay with immersion in aqueous medium. Cell culture and MTT assays showed that the surface microstructure and the ion dissolution products from teOCP/nBG components could enhance the cell proliferation, and especially the composite membranes was suitable for supporting the adhesion and growth behavior of human bone marrow mesenchymal stem cells (hBMSCs) in comparison with the CS/ALG pure polymer membranes. These results suggest that the new CS/ALG-teOCP/nBG composite membrane is highly bioactive and biodegradable, and favorable for guiding bone regeneration.

  5. Preparation of core-shell structure Fe3 O4 @SiO2 superparamagnetic microspheres immoblized with iminodiacetic acid as immobilized metal ion affinity adsorbents for His-tag protein purification.

    PubMed

    Ni, Qian; Chen, Bing; Dong, Shaohua; Tian, Lei; Bai, Quan

    2016-04-01

    The core-shell structure Fe3 O4 /SiO2 magnetic microspheres were prepared by a sol-gel method, and immobiled with iminodiacetic acid (IDA) as metal ion affinity ligands for protein adsorption. The size, morphology, magnetic properties and surface modification of magnetic silica nanospheres were characterized by various modern analytical instruments. It was shown that the magnetic silica nanospheres exhibited superparamagnetism with saturation magnetization values of up to 58.1 emu/g. Three divalent metal ions, Cu(2+) , Ni(2+) and Zn(2+) , were chelated on the Fe3 O4 @SiO2 -IDA magnetic microspheres to adsorb lysozyme. The results indicated that Ni(2+) -chelating magnetic microspheres had the maximum adsorption capacity for lysozyme of 51.0 mg/g, adsorption equilibrium could be achieved within 60 min and the adsorbed protein could be easily eluted. Furthermore, the synthesized Fe3 O4 @SiO2 -IDA-Ni(2+) magnetic microspheres were successfully applied for selective enrichment lysozyme from egg white and His-tag recombinant Homer 1a from the inclusion extraction expressed in Escherichia coli. The result indicated that the magnetic microspheres showed unique characteristics of high selective separation behavior of protein mixture, low nonspecific adsorption, and easy handling. This demonstrates that the magnetic silica microspheres can be used efficiently in protein separation or purification and show great potential in the pretreatment of the biological sample.

  6. Preparation and characterization of a novel sodium alginate incorporated self-assembled Fmoc-FF composite hydrogel.

    PubMed

    Gong, Xiao; Branford-White, Christopher; Tao, Lei; Li, Shubai; Quan, Jing; Nie, Huali; Zhu, Limin

    2016-01-01

    Dipeptides and their derivatives have attracted tremendous attention owning to their excellent abilities of self-assemble assembling into various structures which have great potentials for applications in biology and/or nanotechnology. In the present study, we dedicate to fabricate a rigid and structure controllable Fmoc-FF/SA composite hydrogel. We found that the modified dipeptide, fluorenyl-9-methoxycarbonyl (Fmoc)-diphenylalanine (Phe-Phe) can self-assemble into rigid hydrogels with structures of nanowires, layered thin films or honeycombs as the change of sodium alginate (SA) concentration. Meanwhile, CD-spectroscopy demonstrated that SA appeared to control the process, but it did not change the arrangement of the Fmoc-FF peptide. Our results demonstrated that the formed hydrogel showed physical and chemical stability as well as possessing good biocompatibility. Rheological measurements showed that the addition of SA could improve the stability of the hydrogel. Cell viability assay revealed that the Fmoc-FF and Fmoc-FF/SA hydrogels are both beneficial for cell proliferation in-vitro. Our results indicated that the fabricated Fmoc-FF/SA composite hydrogels could be used in tissue engineering and drug delivery in the future.

  7. Preparation and characterization of nano-sized hydroxyapatite/alginate/chitosan composite scaffolds for bone tissue engineering.

    PubMed

    Kim, Hye-Lee; Jung, Gil-Yong; Yoon, Jun-Ho; Han, Jung-Suk; Park, Yoon-Jeong; Kim, Do-Gyoon; Zhang, Miqin; Kim, Dae-Joon

    2015-09-01

    The aim of this study was to develop chitosan composite scaffolds with high strength and controlled pore structures by homogenously dispersed nano-sized hydroxyapatite (nano-HAp) powders. In the fabrication of composite scaffolds, nano-HAp powders distributed in an alginate (AG) solution with a pH higher than 10 were mixed with a chitosan (CS) solution and then freeze dried. While the HAp content increased up to 70 wt.%, the compressive strength and the elastic modulus of the composite scaffolds significantly increased from 0.27 MPa and 4.42 MPa to 0.68 MPa and 13.35 MPa, respectively. Higher content of the HAp also helped develop more differentiation and mineralization of the MC3T3-E1 cells on the composite scaffolds. The uniform pore structure and the excellent mechanical properties of the HAp/CS composite scaffolds likely resulted from the use of the AG solution at pH 10 as a dispersant for the nano-HAp powders.

  8. Biocompatibility of mannuronic acid-rich alginates.

    PubMed

    Klöck, G; Pfeffermann, A; Ryser, C; Gröhn, P; Kuttler, B; Hahn, H J; Zimmermann, U

    1997-05-01

    Highly purified algin preparations free of adverse contaminants with endotoxins and other mitogens recently became available by a new purification process (Klöck et al., Appl. Microbiol. Biotechnol., 1994, 40, 638-643). An advantage of this purification protocol is that it can be applied to alginates with various ratios of mannuronic acid to guluronic acid. High mannuronic acid alginate capsules are of particular practical interest for cell transplantation and for biohybrid organs, because mannuronate-rich alginates are usually less viscous, allowing one to make gels with a higher alginate content. This will increase their stability and reduce the diffusion permeability and could therefore protect immobilized cells more efficiently against the host immune system. Here we report the biocompatibility of purified, mannuronic acid-rich alginate (68% mannuronate residues) in a series of in vitro, as well as in vivo, assays. In contrast to raw alginate extracts, the purified product showed no mitogenic activity towards murine lymphocytes in vitro. Its endotoxin content was reduced to the level of the solvent. Animal studies with these new, purified algin formulations revealed the absence of a mitogen-induced foreign body reaction, even when the purified material (after cross-linking with Ba2+ ions) is implanted into animal models with elevated macrophage activity (diabetes-prone BB/OK rat). Thus, alginate capsules with high mannuronic acid content become available for applications such as implantation. In addition to the utilization as implantable cell reactors in therapy and biotechnology, these purified algins have broad application potential as ocular fillings, tissue replacements, microencapsulated growth factors and/or interleukins or slow-release dosage forms of antibodies, surface coatings of sensors and other invasive medical devices, and in encapsulation of genetically engineered cells for gene therapy.

  9. In situ one-pot preparation of superparamagnetic hydrophilic porous microspheres for covalently immobilizing penicillin G acylase to synthesize amoxicillin

    NASA Astrophysics Data System (ADS)

    Xue, Ping; Gu, Yaohua; Su, Weiguang; Shuai, Huihui; Wang, Julan

    2016-01-01

    Magnetic hydrophilic porous microspheres were successfully one-pot synthesized for the first time via in situ inverse suspension polymerization of glycidyl methacrylate, N,N‧-methylene bisacrylamide and 2-hydroxyethyl methacrylate in the presence of Fe3+ and Fe2+ dispersed in formamide, which were denoted as magnetic Fe3O4-GMH microspheres. The morphology and properties of magnetic Fe3O4-GMH microspheres were characterized by SEM, VSM, XRD, FTIR, and so on. The formamide content had an important influence on the morphology of Fe3O4-GMH, and nearly perfectly spherical Fe3O4-GMH particles were formed when the amount of formamide was 15 ml. The diameters of the microspheres were in the range of 100-200 μm and Fe3O4-GMH exhibited superparamagnetic behavior with the saturation magnetization of 5.44 emu/g. The specific surface area of microspheres was 138.7 m2/g, the average pore diameter and pore volume were 15.1 nm and 0.60 cm3/g, respectively. The content of oxirane groups on Fe3O4-GMH was 0.40 mmol/g. After penicillin G acylase (PGA) was covalently immobilized on Fe3O4-GMH microspheres, the catalytic performance for amoxicillin synthesis by 6-aminopenicillanic acid and D-hydroxyphenylglycine methyl ester was largely improved. As a result, 90.1% amoxicillin yield and 1.18 of the synthesis/hydrolysis (S/H) ratio were achieved on PGA/Fe3O4-GMH with ethylene glycol as solvent, but only 62.6% amoxicillin yield and 0.37 of the S/H ratio were obtained on free PGA under the same reaction conditions. Furthermore, the amoxicillin yield and S/H ratio were still kept at 88.2% and 1.06, respectively after the immobilized PGA was magnetically separated and recycled for 10 times, indicating that PGA/Fe3O4-GMH had a very good reusability.

  10. In Vitro and In Vivo preparation evaluations of bleomycin implants and microspheres Prepared with DL-poly (lactide-co-glycolide).

    PubMed

    D'Souza, R; Mutalik, S; Udupa, N

    2006-02-01

    In this investigation, poly(lactide-co-glycolide) (PLGA) gel implants and microspheric depot systems of bleomycin (BLM) were formulated and evaluated in vivo in mice bearing transplantable solid tumor (fibrosarcoma). The pharmacodynamic studies showed that both the formulations retarded tumor growth significantly (p<0.05) when compared to the control animals (without any drug treatment). Preliminary pharmacokinetic studies illustrated controlled release of the drug into the systemic circulation to elicit the anti-neoplastic action. The gel implants showed better release characteristics and greater pharmacodynamic action when compared to the microspheres, thus demonstrating the feasibility of employing biodegradable depot polymer gel matrix for chronic cancer therapy.

  11. Filling Porous Microspheres With Magnetic Material

    NASA Technical Reports Server (NTRS)

    Chang, Manchium; Colvin, Michael S.

    1990-01-01

    New process produces magnetic microspheres with controllable sizes, compositions, and properties for use in medical diagnostic tests, biological research, and chemical processes. Paramagnetic microspheres also made with process. Porous plastic microspheres prepared by polymerization of monomer in diluent by cross-linking agent. When diluent removed, it leaves tiny pores throughout polymerized spheres. Size and distribution of pores determined by amount and type of diluent and cross-linking agent.

  12. Alginate composites for bone tissue engineering: a review.

    PubMed

    Venkatesan, Jayachandran; Bhatnagar, Ira; Manivasagan, Panchanathan; Kang, Kyong-Hwa; Kim, Se-Kwon

    2015-01-01

    Bone is a complex and hierarchical tissue consisting of nano hydroxyapatite and collagen as major portion. Several attempts have been made to prepare the artificial bone so as to replace the autograft and allograft treatment. Tissue engineering is a promising approach to solve the several issues and is also useful in the construction of artificial bone with materials including polymer, ceramics, metals, cells and growth factors. Composites consisting of polymer-ceramics, best mimic the natural functions of bone. Alginate, an anionic polymer owing enormous biomedical applications, is gaining importance particularly in bone tissue engineering due to its biocompatibility and gel forming properties. Several composites such as alginate-polymer (PLGA, PEG and chitosan), alginate-protein (collagen and gelatin), alginate-ceramic, alginate-bioglass, alginate-biosilica, alginate-bone morphogenetic protein-2 and RGD peptides composite have been investigated till date. These alginate composites show enhanced biochemical significance in terms of porosity, mechanical strength, cell adhesion, biocompatibility, cell proliferation, alkaline phosphatase increase, excellent mineralization and osteogenic differentiation. Hence, alginate based composite biomaterials will be promising for bone tissue regeneration. This review will provide a broad overview of alginate preparation and its applications towards bone tissue engineering.

  13. Characterization of a Polyamine Microsphere and Its Adsorption for Protein

    PubMed Central

    Wang, Feng; Liu, Pei; Nie, Tingting; Wei, Huixian; Cui, Zhenggang

    2013-01-01

    A novel polyamine microsphere, prepared from the water-in-oil emulsion of polyethylenimine, was characterized. The investigation of scanning electron microscopy showed that the polyamine microsphere is a regular ball with a smooth surface. The diameter distribution of the microsphere is 0.37–4.29 μm. The isoelectric point of the microsphere is 10.6. The microsphere can adsorb proteins through the co-effect of electrostatic and hydrophobic interactions. Among the proteins tested, the highest value of adsorption of microsphere, 127.8 mg·g−1 microsphere, was obtained with lipase. In comparison with other proteins, the hydrophobic force is more important in promoting the adsorption of lipase. The microsphere can preferentially adsorb lipase from an even mixture of proteins. The optimum temperature and pH for the selective adsorption of lipase by the microsphere was 35 °C and pH 7.0. PMID:23344018

  14. Inter-grade and inter-batch variability of sodium alginate used in alginate-based matrix tablets.

    PubMed

    Fu, Shao; Buckner, Ira S; Block, Lawrence H

    2014-10-01

    The purpose of this study is to characterize the inter-grade and inter-batch variability of sodium alginate used in the formulation of matrix tablets. Four different grades and three batches of one grade of sodium alginate were used to prepare matrix tablets. Swelling, erosion, and drug release tests of sodium alginate matrix tablets were conducted in a USP dissolution apparatus. Substantial differences in swelling and erosion behavior of sodium alginate matrix tablets were evident among different viscosity grades. Even different batches of the same grade exhibit substantial differences in the swelling and erosion behavior of their matrix tablets. The erosion behavior of sodium alginate matrix tablets can be partly explained by their rheological properties (both apparent viscosity and viscoelasticity) in solution. Sodium alginate with higher apparent viscosity and viscoelasticity in solution show slower erosion rate and higher swelling rate. Compacts prepared from grades or batches with higher viscosity and higher viscoelasticity show slower drug release. For grades or batches with similar apparent viscosities, apparent viscosities of sodium alginate solution at low concentration alone are not sufficient to predict the functionality of sodium alginate in matrix tablets. Viscoelastic properties of sodium alginate solutions at one high concentration corresponding to the polymer gel state, may be suitable indicia of the extended release behavior of sodium alginate matrix tablets.

  15. Facile preparation of multifunctional uniform magnetic microspheres for T1-T2 dual modal magnetic resonance and optical imaging.

    PubMed

    Zhang, Li; Liang, Shuang; Liu, Ruiqing; Yuan, Tianmeng; Zhang, Shulai; Xu, Zushun; Xu, Haibo

    2016-08-01

    Molecular imaging is of significant importance for early detection and diagnosis of cancer. Herein, a novel core-shell magnetic microsphere for dual modal magnetic resonance imaging (MRI) and optical imaging was produced by one-pot emulsifier-free emulsion polymerization, which could provide high resolution rate of histologic structure information and realize high sensitive detection at the same time. The synthesized magnetic microspheres composed of cores containing oleic acid (OA) and sodium undecylenate (NaUA) modified Fe3O4 nanoparticles and styrene (St), Glycidyl methacrylate (GMA), and polymerizable lanthanide complexes (Gd(AA)3Phen and Eu(AA)3Phen) polymerized on the surface for outer shells. Fluorescence spectra show characteristic emission peaks from Eu(3+) at 590nm and 615nm and vivid red fluorescence luminescence can be observed by 2-photon confocal scanning laser microscopy (CLSM). In vitro cytotoxicity tests based on the MTT assay demonstrate good cytocompatibility, the composites have longitudinal relaxivity value (r1) of 8.39mM(-1)s(-1) and also have transverse relaxivity value (r2) of 71.18mM(-1)s(-1) at clinical 3.0 T MR scanner. In vitro and in vivo MRI studies exhibit high signal enhancement on both T1- and T2-weighted MR images. These fascinating multifunctional properties suggest that the polymer microspheres have large clinical potential as multi-modal MRI/optical probes.

  16. Preparation and in vitro release studies of ibuprofen-loaded films and microspheres made from graft copolymers of poly(L-lactic acid) on acrylic backbones.

    PubMed

    Gallardo, A; Eguiburu, J L; Fernandez Berridi, M J; San Román, J

    1998-11-13

    The present article describes the preparation of films of various thickness and microspheres from new resorbable graft copolymers of polyacrylic (methyl methacrylate, MMA, or methyl acrylate, MA), or polyvinylic (vinyl pyrrolidone, VP) chains and poly(l-lactic acid) (PLLA) side blocks charged with 15-20% of ibuprofen (IBU) (a non-steroidic antiinflammatory agent). In the case of MMA-LLA and MA-LLA graft copolymers the release of IBU in buffered solution is modulated by the flexibility of the copolymer chains in a first step of one to two days and in a second step by the diffusive properties of the system as well as by the biodegradation of the polymers. The VP-PLLA graft copolymers are highly hydrophilic and the release of IBU is modulated by the diffusion of the drug through the swollen system. Specific interactions between the IBU molecules and the pyrrolidone rings also participate in the kinetic behaviour of the release process.

  17. Fluorescent microspheres

    NASA Technical Reports Server (NTRS)

    Rembaum, A.

    1978-01-01

    Latex particles with attached antibodies have potential biochemical and environmental applications. Human red blood cells and lymphocytes have been labeled with fluorescent microspheres by either direct or indirect immunological technique. Immunolatex spheres can also be used for detecting and localizing specific cell surface receptors. Hormones and toxins may also be bondable.

  18. Preparation and characterization of gatifloxacin-loaded sodium alginate hydrogel membranes supplemented with hydroxypropyl methylcellulose and hydroxypropyl cellulose polymers for wound dressing

    PubMed Central

    Prabu, Durai; Majdalawieh, Amin F.; Abu-Yousef, Imad A.; Inbasekaran, Kadambari; Balasubramaniam, Tharani; Nallaperumal, Narayanan; Gunasekar, Conjeevaram J.

    2016-01-01

    Introduction: The aim of this study is to evaluate gatifloxacin-loaded sodium alginate hydrogel membranes, supplemented with glycerol (a plasticizer), glutaraldehyde (a cross-linking agent), and hydroxypropyl methylcellulose (HPMC) or hydroxypropyl cellulose (HPC) polymers, as potential wound dressing materials based on their physicochemical properties and the sustain-release phenomenon. Materials and Methods: The physicochemical properties of the prepared hydrogel membranes were evaluated by several methods including Fourier transform infrared and differential scanning calorimetry. Different techniques were used to assess the swelling behavior, tensile strength and elongation, % moisture absorption, % moisture loss, water vapor transmission rate (WVTR), and microbial penetration for the hydrogel membranes. In vitro gatifloxacin release from the hydrogel membranes was examined using the United States Pharmacopeia XXIII dissolution apparatus. Four kinetics models (zero-order, first-order, Higuchi equation, and Korsmeyer-Peppas equation) were applied to study drug release kinetics. Results: The addition of glycerol, glutaraldehyde, HPMC, and HPC polymers resulted in a considerable increase in the tensile strength and flexibility/elasticity of the hydrogel membranes. WVTR results suggest that hydrated hydrogel membranes can facilitate water vapor transfer. None of the hydrogel membranes supported microbial growth. HPMC-treated and HPC-treated hydrogel membranes allow slow, but sustained, release of gatifloxacin for 48 h. Drug release kinetics revealed that both diffusion and dissolution play an important role in gatifloxacin release. Conclusions: Given their physicochemical properties and gatifloxacin release pattern, HPMC-treated and HPC-treated hydrogel membranes exhibit effective and sustained drug release. Furthermore, HPMC-treated and HPC-treated hydrogel membranes possess physiochemical properties that make them effective and safe wound dressing materials. PMID

  19. Compatible compositions based on aqueous polyurethane dispersions and sodium alginate.

    PubMed

    Daemi, Hamed; Barikani, Mehdi; Barmar, Mohammad

    2013-01-30

    A series of aqueous polyurethane dispersions were synthesized by the reaction of polytetramethylene glycol and isophorone diisocyanate, extended with dimethylol propionic acid. Their chemical structures were characterized using FTIR, (1)H NMR, and (13)C NMR, and thermal properties were determined by DMTA. Then, a number of aqueous polyurethane dispersions-sodium alginate (PUD/SA) compositions were prepared by addition of sodium alginate solution with different concentrations into the aqueous polyurethane dispersion. Characterization of chemical structure and thermal properties of these blends were performed by FTIR, EDX and DMTA, respectively. The morphology of the alginate in polyurethane matrix was studied by SEM. The hydrophilicity of the prepared samples decreases by increasing the content of sodium alginate in blends. These observations were attributed to the increase of hydrophilicity of the blends as a consequence of addition of hydrophilic carboxylate, hydroxyl and ether functional groups of the alginate to them.

  20. Microspheres prepared with different co-polymers of poly(lactic-glycolic acid) (PLGA) or with chitosan cause distinct effects on macrophages.

    PubMed

    Bitencourt, Claudia da Silva; Silva, Letícia Bueno da; Pereira, Priscilla Aparecida Tartari; Gelfuso, Guilherme Martins; Faccioli, Lúcia Helena

    2015-12-01

    Microencapsulation of bioactive molecules for modulating the immune response during infectious or inflammatory events is a promising approach, since microspheres (MS) protect these labile biomolecules against fast degradation, prolong the delivery over longer periods of time and, in many situations, target their delivery to site of action, avoiding toxic side effects. Little is known, however, about the influence of different polymers used to prepare MS on macrophages. This paper aims to address this issue by evaluating in vitro cytotoxicity, phagocytosis profile and cytokines release from alveolar macrophages (J-774.1) treated with MS prepared with chitosan, and four different co-polymers of PLGA [poly (lactic-co-glycolic acid)]. The five MS prepared presented similar diameter and zeta potential each other. Chitosan-MS showed to be cytotoxic to J-774.1 cells, in contrast to PLGA-MS, which were all innocuous to this cell linage. PLGA 5000-MS was more efficiently phagocytized by macrophages compared to the other MS tested. PLGA 5000-MS and 5002-MS induced significant production of TNF-α, while 5000-MS, 5004-MS and 7502-MS decreased spontaneous IL-6 release. Nevertheless, only PLGA 5002-MS induced significant NFkB/SEAP activation. These findings together show that MS prepared with distinct PLGA co-polymers are differently recognized by macrophages, depending on proportion of lactic and glycolic acid in polymeric chain, and on molecular weight of the co-polymer used. Selection of the most adequate polymer to prepare a microparticulate drug delivery system to modulate immunologic system may take into account, therefore, which kind of immunomodulatory response is more adequate for the required treatment.

  1. Dental mesenchymal stem cells encapsulated in alginate hydrogel co-delivery microencapsulation system for cartilage regeneration

    PubMed Central

    Moshaverinia, Alireza; Xu, Xingtian; Chen, Chider; Akiyama, Kentaro; Snead, Malcolm L; Shi, Songtao

    2013-01-01

    Dental-derived MSCs are promising candidates for cartilage regeneration, with high chondrogenic differentiation capacity. This property contributes to making dental MSCs an advantageous therapeutic option compared to current treatment modalities. The MSC delivery vehicle is the principal determinant for the success of MSC-mediated cartilage regeneration therapies. The objectives of this study were to: (1) develop a novel co-delivery system based on TGF-β1 loaded RGD-coupled alginate microspheres encapsulating Periodontal Ligament Stem Cells (PDLSCs) or Gingival Mesenchymal Stem Cells (GMSCs); and (2) investigate dental MSC viability and chondrogenic differentiation in alginate microspheres. The results revealed the sustained release of TGF-β1 from the alginate microspheres. After 4 weeks of chondrogenic differentiation in vitro, PDLSCs, GMSCs as well as human bone marrow mesenchymal stem cells (hBMMSC) (as positive control) revealed chondrogenic gene expression markers (Col II and Sox-9) via qPCR, as well as matrix positively stained by toluidine blue and safranin-O. In animal studies, ectopic cartilage tissue regeneration was observed inside and around the transplanted microspheres, confirmed by histochemical and immunofluorescent staining. Interestingly, PDLSCs showed more chondrogenesis than GMSCs and hBMMSCs (P<0.05). Taken together, these results suggest that RGD-modified alginate microencapsulating dental MSCs make a promising candidate for cartilage regeneration. Our results highlight the vital role played by the microenvironment, as well as value of presenting inductive signals for viability and differentiation of MSCs. PMID:23891740

  2. Alginate cryogel based glucose biosensor

    NASA Astrophysics Data System (ADS)

    Fatoni, Amin; Windy Dwiasi, Dian; Hermawan, Dadan

    2016-02-01

    Cryogel is macroporous structure provides a large surface area for biomolecule immobilization. In this work, an alginate cryogel based biosensor was developed to detect glucose. The cryogel was prepared using alginate cross-linked by calcium chloride under sub-zero temperature. This porous structure was growth in a 100 μL micropipette tip with a glucose oxidase enzyme entrapped inside the cryogel. The glucose detection was based on the colour change of redox indicator, potassium permanganate, by the hydrogen peroxide resulted from the conversion of glucose. The result showed a porous structure of alginate cryogel with pores diameter of 20-50 μm. The developed glucose biosensor was showed a linear response in the glucose detection from 1.0 to 5.0 mM with a regression of y = 0.01x+0.02 and R2 of 0.994. Furthermore, the glucose biosensor was showed a high operational stability up to 10 times of uninterrupted glucose detections.

  3. Facile preparation of well-dispersed CeO2-ZnO composite hollow microspheres with enhanced catalytic activity for CO oxidation.

    PubMed

    Xie, Qingshui; Zhao, Yue; Guo, Huizhang; Lu, Aolin; Zhang, Xiangxin; Wang, Laisen; Chen, Ming-Shu; Peng, Dong-Liang

    2014-01-08

    In this article, well-dispersed CeO2-ZnO composite hollow microspheres have been fabricated through a simple chemical reaction followed by annealing treatment. Amorphous zinc-cerium citrate hollow microspheres were first synthesized by dispersing zinc citrate hollow microspheres into cerium nitrate solution and then aging at room temperature for 1 h. By calcining the as-produced zinc-cerium citrate hollow microspheres at 500 °C for 2 h, CeO2-ZnO composite hollow microspheres with homogeneous composition distribution could be harvested for the first time. The resulting CeO2-ZnO composite hollow microspheres exhibit enhanced activity for CO oxidation compared with CeO2 and ZnO, which is due to well-dispersed small CeO2 particles on the surface of ZnO hollow microspheres and strong interaction between CeO2 and ZnO. Moreover, when Au nanoparticles are deposited on the surface of the CeO2-ZnO composite hollow microspheres, the full CO conversion temperature of the as-produced 1.0 wt % Au-CeO2-ZnO composites reduces from 300 to 60 °C in comparison with CeO2-ZnO composites. The significantly improved catalytic activity may be ascribed to the strong synergistic interplay between Au nanoparticles and CeO2-ZnO composites.

  4. Preparation and microwave absorbing property of Ni-Zn ferrite-coated hollow glass microspheres with polythiophene

    NASA Astrophysics Data System (ADS)

    Li, Lindong; Chen, Xingliang; Qi, Shuhua

    2016-11-01

    The composite of hollow glass microspheres (HMG) coated by Ni0.7Zn0.3Fe2O4 particles was fabricated via sol-gel method, and then the ternary composite (HMG/Ni0.7Zn0.3Fe2O4/PT) was synthesized by in situ polymerization. The electrical property, magnetic performance and reflection loss of the composites were measured, and the results suggest that the conductivity and the saturation magnetization (Ms) of HMG/Ni0.7Zn0.3Fe2O4/PT reach 6.87×10-5 S/cm and 11.627 emu/g, respectively. The ternary composite has good microwave absorbing properties (Rmin=-13.79 dB at 10.51 GHz) and the bandwidth less than -10 dB can reach 2.6 GHz (from 9.4 to 12.0 GHz) in X band (8.2-12.4 GHz). The morphology and chemical structure of the samples were measured through scanning electron microscopy (SEM), X-Ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). This paper also analyzes the relationship between the reflection loss of the absorber and its thickness.

  5. Microradiographic microsphere manipulator

    DOEpatents

    Singleton, R.M.

    A method and apparatus is disclosed for radiographic characterization of small hollow spherical members (microspheres), constructed of either optically transparent or opaque materials. The apparatus involves a microsphere manipulator which holds a batch of microspheres between two parallel thin plastic films for contact microradiographic characterization or projection microradiography thereof. One plastic film is translated relative to and parallel to the other to roll the microspheres through any desired angle to allow different views of the microspheres.

  6. Microradiographic microsphere manipulator

    DOEpatents

    Singleton, Russell M.

    1980-01-01

    A method and apparatus for radiographic characterization of small hollow spherical members (microspheres), constructed of either optically transparent or opaque materials. The apparatus involves a microsphere manipulator which holds a batch of microspheres between two parallel thin plastic films for contact microradiographic characterization or projection microradiography thereof. One plastic film is translated to relative to and parallel to the other to roll the microspheres through any desired angle to allow different views of the microspheres.

  7. 21 CFR 184.1133 - Ammonium alginate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... prepared by the neutralization of purified alginic acid with appropriate pH control agents. (b) The ingredient meets the specifications of the Food Chemicals Codex, 3d Ed. (1981), p. 18, which is incorporated... food Maximum level of use in food (as served) (percent) Functional use Confections, frostings, §...

  8. Hybrid microspheres

    NASA Technical Reports Server (NTRS)

    Rembaum, Alan (Inventor); Yen, Richard C. K. (Inventor)

    1985-01-01

    Substrates, particularly inert synthetic organic resin beads (10) or sheet (12) such as polystyrene are coated with a covalently bound layer (24) of polyacrolein by irradiation a solution (14) of acrolein or other aldehyde with high intensity radiation. Individual microspheres (22) are formed which attach to the surface to form the aldehyde containing layer (24). The aldehyde groups can be converted to other functional groups by reaction with materials such as hydroxylamine. Adducts of proteins such as antibodies or enzymes can be formed by direct reaction with the surface aldehyde groups.

  9. Preparation with a facile template-free method of uniform-sized mesoporous microspheres of rare earth (La, Ce, Pr, Nd) oxides

    SciTech Connect

    Ji, Pengfei; Xing, Mingyang; Bagwasi, Segomotso; Tian, Baozhu; Chen, Feng; Zhang, Jinlong

    2011-11-15

    Highlights: {yields} Mesoporous microspheres of light rare earth hydroxycarbonates and oxides were fabricated. {yields} The supersaturated urea has important effect on formation of mesoporous microspheres. {yields} The influences of [cation]/[urea] ratio and amount of water on the formation of spherical crystallites were discussed. -- Abstract: Mesoporous microspheres of light rare earth (La, Ce, Pr, Nd) hydroxycarbonates and oxides were successfully fabricated by a facile surfactant free hydrothermal method in supersaturated aqueous urea solution. The techniques of XRD, TEM, SEM, TG/DTA and N{sub 2} adsorption-desorption were employed to investigate the structure and formation process of mesoporous microspheres. It was revealed that supersaturated urea not only serve as a reactant and pH modifier in the reaction system but also guide the oriented assembly of hydroxycarbonate crystallites into microspheres by acting as a structure-directing agent. The microspheres of rare earth oxides could easily be obtained by simple calcination of corresponding hydroxycarbonates precursors without undergoing morphology changes. In addition, the influences of rare earth precursor and urea concentrations on the formation of microspheres were also investigated.

  10. Preparation of grafted microspheres CPVA-g-PSSS and studies on their drug-carrying and colon-specific drug delivery properties.

    PubMed

    Gao, Baojiao; Fang, Li; Men, Jiying; Zhang, Yanyan

    2013-04-01

    Sodium 4-styrene sulfonate (SSS) was graft-polymerized on the surfaces of crosslinked polyvinyl alcohol (CPVA) microspheres in a manner of surface-initiated graft-polymerization by using cerium salt-hydroxyl group redox initiation system, obtaining the grafted microspheres CPVA-g-PSSS. The chemical structure and physicochemical characters of CPVA-g-PSSS microspheres were fully characterized with infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and zeta potential determination. The aim of this work is to constitute a novel colon-specific drug delivery system via molecular design by using CPVA-g-PSSS microspheres as the drug-carrying material and by taking metronidazole (MTZ) as the model drug. The drug-carrying ability and mechanism of the grafted microspheres CPVA-g-PSSS for MTZ were investigated. Finally, in-vitro release tests for the drug-carrying microspheres were conducted. The experimental results show that in an acidic medium, the grafted microspheres CPVA-g-PSSS exhibit strong adsorption ability for MTZ by driving of electrostatic interaction, and have an adsorption capacity of 112 mg/g, displaying the high efficiency of drug-carrying. The in-vitro release behavior of the drug-carried microspheres is highly pH-sensitive. In the medium of pH=1, the drug-carrying microspheres do not release the drug, whereas in the medium of pH=7.4, a sudden delivery phenomenon of the drug will occur, displaying an excellent colon-specific drug delivery behavior.

  11. Small-angle X-ray scattering and rheological characterization of alginate gels. 3. Alginic acid gels.

    PubMed

    Draget, Kurt Ingar; Stokke, Bjørn T; Yuguchi, Yoshiaki; Urakawa, Hiroshi; Kajiwara, Kanji

    2003-01-01

    Alginic acid gels were studied by small-angle X-ray scattering and rheology to elucidate the influence of alginate chemical composition and molecular weight on the gel elasticity and molecular structure. The alginic acid gels were prepared by homogeneous pH reduction throughout the sample. Three alginates with different chemical composition and sequence, and two to three different molecular weights of each sample were examined. Three alginate samples with fractions of guluronic acid residues of 0.39 (LoG), 0.50 (InG), and 0.68 (HiG), covering the range of commercially available alginates, were employed. The excess scattering intensity I of the alginic acid gels was about 1 order of magnitude larger and exhibited a stronger curvature toward low q compared to ionically cross-linked alginate. The I(q) were decomposed into two components by assuming that the alginic acid gel is composed of aggregated multiple junctions and single chains. Time-resolved experiments showed a large increase in the average size of aggregates and their weight fraction within the first 2 h after onset of gelling, which also coincides with the most pronounced rheological changes. At equilibrium, little or no effect of molecular weight was observed, whereas at comparable molecular weights, an increased scattering intensity with increasing content of guluronic acid residues was recorded, probably because of a larger apparent molecular mass of domains. The results suggest a quasi-ordered junction zone is formed in the initial stage, followed by subsequent assembling of such zones, forming domains in the order of 50 A. The average length of the initial junction zones, being governed by the relative fraction of stabilizing G-blocks and destabilizing alternating (MG) blocks, determines the density of the final random aggregates. Hence, high-G alginates give alginic acid gels of a higher aggregate density compared to domains composed of loosely packed shorter junction zones in InG or LoG system.

  12. Preparation of chitosan/poly(acrylic acid) magnetic composite microspheres and applications in the removal of copper(II) ions from aqueous solutions.

    PubMed

    Yan, Han; Yang, Lingyun; Yang, Zhen; Yang, Hu; Li, Aimin; Cheng, Rongshi

    2012-08-30

    In this current work, the magnetic composite microspheres (MCM), consisting of Fe(3)O(4) nanoparticles and poly(acrylic acid) (PAA) blended chitosan (CS), were prepared successfully by a simple method, co-precipitation of the compounds in alkaline solution. SEM, FTIR and TG techniques have been applied to investigate the structures of the MCM materials. The vibrating-sample magnetometer (VSM) measurement illustrated a paramagnetic property as well as a fast magnetic response, which indicated the significant separability of the MCM in the aqueous suspensions. Then, the MCM materials were employed as absorbents for removal of copper(II) (Cu(II)) ions from aqueous solutions. The fundamental adsorption behaviors of MCM were studied also. Experimental results revealed that the CS/PAA-MCM had greater adsorption capacity than CS-MCM, and PAA played an important role for the adsorption of Cu(II) ions. Moreover, the adsorption isotherms were all well described by the Langmuir model, while the adsorption kinetics followed the pseudo-second order equation. Furthermore, the adsorbent could be easily regenerated at lower pH and reused almost without any loss of adsorption capacity. On the contrary, the Cu(II) ions loaded CS-MCM and CS/PAA-MCM were stable enough at pH higher than 4.0, and both exhibited efficient phosphate removal with maximal uptakes around 63.0 and 108.0 mg Pg(-1), respectively.

  13. Preparation of photonic-magnetic responsive molecularly imprinted microspheres and their application to fast and selective extraction of 17β-estradiol.

    PubMed

    Peng, Hailong; Luo, Mei; Xiong, Hua; Yu, Ningxiang; Ning, Fangjian; Fan, Jieping; Zeng, Zheling; Li, Jinhua; Chen, Lingxin

    2016-04-15

    Photonic-magnetic responsive molecularly imprinted microspheres (PM-MIMs) were prepared by seed polymerization, through suitable functionalization of magnetic nanoparticles for further coating with photoresponsive functional monomer and imprinted layers, and then were successfully applied to the fast and selective extraction of 17β-estradiol (17β-E2) from real samples. The PM-MIMs possessed a sandwich micro-spherical structure containing Fe3O4 core, SiO2 middle layer, and MIPs shell with thickness of 25 nm. The PM-MIMs displayed excellent photoresponsive properties and could be rapidly separated from solutions under an external magnet. The PM-MIMs had specific affinity towards 17β-E2 with high adsorption capacity (Qmax=0.84 mg g(-1)) and fast binding kinetics (Kd=26.08 mg L(-1)). The PM-MIMs proved to be an ideal photoswitch with the ability of reversible uptake and release of 17β-E2 upon alternate 365 and 440 nm irradiation: 45.0% of 17β-E2 released from the PM-MIMs upon 365 nm irradiation, and 94.0% of the released 17β-E2 was rebound to the PM-MIMs at 440 nm. Accordingly, the PM-MIMs were applied for fast separation and extraction of 17β-E2 followed by HPLC-UV determination, presenting the low limit of detection (LOD, S/N=3) and quantification (LOQ, S/N=10) of 0.18 and 0.62 μmol L(-1), respectively. The high recoveries for spiked milk powder and drinking water samples were in the range of 97.5-113.0% with relative standard deviations less than 4.4%. This study reasonably combined photonic response, magnetic separation and surface imprinting, which endowed the PM-MIMs with significant advantages of high adsorption capacity and fast binding kinetics, convenient separation and recycled use, and simple rapid eco-benign adsorption/elution processes for template molecules. Thus, the PM-MIMs based method may be a simple, rapid, convenient, cost-effective and environmentally-friendly way for simultaneous separation, enrichment and detection of trace 17β-E2 in

  14. Alginate gel-coated oil-entrapped alginate-tamarind gum-magnesium stearate buoyant beads of risperidone.

    PubMed

    Bera, Hriday; Boddupalli, Shashank; Nandikonda, Sridhar; Kumar, Sanoj; Nayak, Amit Kumar

    2015-01-01

    A novel alginate gel-coated oil-entrapped calcium-alginate-tamarind gum (TG)-magnesium stearate (MS) composite floating beads was developed for intragastric risperidone delivery with a view to improving its oral bioavailability. The TG-blended alginate core beads containing olive oil and MS as low-density materials were accomplished by ionotropic gelation technique. Effects of polymer-blend ratio (sodium alginate:TG) and crosslinker (CaCl2) concentration on drug entrapment efficiency (DEE, %) and cumulative drug release after 8 h (Q8h, %) were studied to optimize the core beads by a 3(2) factorial design. The optimized beads (F-O) exhibited DEE of 75.19±0.75% and Q8h of 78.04±0.38% with minimum errors in prediction. The alginate gel-coated optimized beads displayed superior buoyancy and sustained drug release property. The drug release profiles of the drug-loaded uncoated and coated beads were best fitted in Higuchi kinetic model with Fickian and anomalous diffusion driven mechanisms, respectively. The optimized beads yielded a notable sustained drug release profile as compared to marketed immediate release preparation. The uncoated and coated Ca-alginate-TG-MS beads were also characterized by SEM, FTIR and P-XRD analyses. Thus, the newly developed alginate-gel coated oil-entrapped alginate-TG-MS composite beads are suitable for intragastric delivery of risperidone over a prolonged period of time.

  15. Development of Risperidone PLGA Microspheres

    PubMed Central

    D'Souza, Susan; Faraj, Jabar A.; Giovagnoli, Stefano; DeLuca, Patrick P.

    2014-01-01

    The aim of this study was to design and evaluate biodegradable PLGA microspheres for sustained delivery of Risperidone, with an eventual goal of avoiding combination therapy for the treatment of schizophrenia. Two PLGA copolymers (50 : 50 and 75 : 25) were used to prepare four microsphere formulations of Risperidone. The microspheres were characterized by several in vitro techniques. In vivo studies in male Sprague-Dawley rats at 20 and 40 mg/kg doses revealed that all formulations exhibited an initial burst followed by sustained release of the active moiety. Additionally, formulations prepared with 50 : 50 PLGA had a shorter duration of action and lower cumulative AUC levels than the 75 : 25 PLGA microspheres. A simulation of multiple dosing at weekly or 15-day regimen revealed pulsatile behavior for all formulations with steady state being achieved by the second dose. Overall, the clinical use of Formulations A, B, C, or D will eliminate the need for combination oral therapy and reduce time to achieve steady state, with a smaller washout period upon cessation of therapy. Results of this study prove the suitability of using PLGA copolymers of varying composition and molecular weight to develop sustained release formulations that can tailor in vivo behavior and enhance pharmacological effectiveness of the drug. PMID:24616812

  16. Carbon microsphere-filled Pyrrone foams.

    NASA Technical Reports Server (NTRS)

    Kimmel, B. G.

    1973-01-01

    Syntactic foam formulations were prepared from mixtures of Pyrrone prepolymers and hollow carbon microspheres. Very low curing shrinkages were obtained for high volume loadings of microspheres. The resulting syntactic foams were found to be remarkably stable over a wide range in temperature. A technique was developed for the emplacement of these foam formulations in polyimide-fiberglass, titanium alloy and stainless steel honeycomb without sacrificing low curing shrinkage or thermal stability.

  17. Porous ZnS/ZnO microspheres prepared through the spontaneous organization of nanoparticles and their application as supports of holding CdTe quantum dots

    SciTech Connect

    Cao Xuebo Lan Xianmei; Zhao Cui; Shen Wenjun; Yao Dan

    2008-05-06

    This manuscript describes a self-organization method for the large-scale production of porous ZnS/ZnO composite microspheres and their application as supports of CdTe quantum dots. Through the reaction of Zn{sup 2+} and urea and thioacetamide at 85 deg. C for 10 min, nanoparticles of cubic ZnS and amorphous ZnO were formed and they present a strong tendency to organize into regular microspheres. The formation of nanopores within the microspheres is related to Ostwald ripening: some small nanoparticles within the microspheres were merged by the larger ones, and as a result, numerous nanopores were generated. Furthermore, when a solvothermal ripening is applied for the porous microspheres, the components within them can be transformed into hexagonal ZnS and ZnO. CdTe quantum dots were introduced into the nanopores to achieve luminescent microspheres through in situ nucleation and growth. And it is expected that, besides semiconducting quantum dots, other functional units, such as magnetic and catalytically activated nanoparticles, can also be introduced into them.

  18. Fabrication and magnetic control of alginate-based rolling microrobots

    NASA Astrophysics Data System (ADS)

    Ali, Jamel; Cheang, U. Kei; Liu, Yigong; Kim, Hoyeon; Rogowski, Louis; Sheckman, Sam; Patel, Prem; Sun, Wei; Kim, Min Jun

    2016-12-01

    Advances in microrobotics for biological applications are often limited due to their complex manufacturing processes, which often utilize cytotoxic materials, as well as limitations in the ability to manipulate these small devices wirelessly. In an effort to overcome these challenges, we investigated a facile method for generating biocompatible hydrogel based robots that are capable of being manipulated using an externally generated magnetic field. Here, we experimentally demonstrate the fabrication and autonomous control of loaded-alginate microspheres, which we term artificial cells. In order to generate these microparticles, we employed a centrifuge-based method in which microspheres were rapidly ejected from a nozzle tip. Specifically, we used two mixtures of sodium alginate; one containing iron oxide nanoparticles and the other containing mammalian cells. This mixture was loaded into a needle that was fixed on top of a microtube containing calcium chloride, and then briefly centrifuged to generate hundreds of Janus microspheres. The fabricated microparticles were then magnetically actuated with a rotating magnetic field, generated using electromagnetic coils, prompting the particles to roll across a glass substrate. Also, using vision-based feedback control, a single artificial cell was manipulated to autonomously move in a programmed pattern.

  19. Bisphosphonate release profiles from magnetite microspheres.

    PubMed

    Miyazaki, Toshiki; Inoue, Tatsuya; Shirosaki, Yuki; Kawashita, Masakazu; Matsubara, Takao; Matsumine, Akihiko

    2014-10-01

    Hyperthermia has been suggested as a novel, minimally invasive cancer treatment method. After implantation of magnetic nano- or microparticles around a tumour through blood vessels, irradiation with alternating magnetic fields facilitates the efficient in situ hyperthermia even for deep-seated tumours. On the basis of this idea, if the microspheres are capable of delivering drugs, they could be promising multifunctional biomaterials effective for chemotherapy as well as hyperthermia. In the present study, magnetite microspheres were prepared by aggregation of the iron oxide colloid in water-in-oil (W/O) emulsion. The release behaviour of alendronate, a typical bisphosphonate, from the microspheres was examined in vitro as a model of the bone tumour prevention and treatment system. The alendronate was successfully incorporated onto the porous magnetite microspheres in vacuum conditions. The drug-loaded microspheres maintained their original spherical shapes even after shaking in ultrapure water for 3 days, suggesting that they have sufficient mechanical integrity for clinical use. It was attributed to high aggregation capability of the magnetite nanoparticles through van der Waals and weak magnetic attractions. The microspheres showed slow release of the alendronate in vitro, resulting from tight covalent or ionic interaction between the magnetite and the alendronate. The release rate was diffusion-controlled type and well controlled by the alendronate concentration in drug incorporation to the microspheres.

  20. Chitosan and alginate biopolymer membranes for remediation of contaminated water with herbicides.

    PubMed

    Agostini de Moraes, Mariana; Cocenza, Daniela Sgarbi; da Cruz Vasconcellos, Fernando; Fraceto, Leonardo Fernandes; Beppu, Marisa Masumi

    2013-12-15

    This study investigated the adsorption behavior of the herbicides diquat, difenzoquat and clomazone on biopolymer membranes prepared with alginate and chitosan (pristine and multi-layer model) for contaminated water remediation applications. Herbicides, at concentrations ranging from 5 μM to 200 μM, were adsorbed in either pure alginate, pure chitosan or a bilayer membrane composed of chitosan/alginate. No adsorption of clomazone was observed on any of the membranes, probably due to lack of electrostatic interactions between the herbicide and the membranes. Diquat and difenzoquat were only adsorbed on the alginate and chitosan/alginate membranes, indicating that this adsorption takes place in the alginate layer. At a concentration of 50 μM, diquat adsorption reaches ca. 95% after 120 min on both the alginate and chitosan/alginate membranes. The adsorption of difenzoquat, at the same concentration, reaches ca. 62% after 120 min on pure alginate membranes and ca. 12% on chitosan/alginate bilayer membranes. The adsorption isotherms for diquat and difenzoquat were further evaluated using the isotherm models proposed by Langmuir and by Freundlich, where the latter represented the best-fit model. Results indicate that adsorption occurs via coulombic interactions between the herbicides and alginate and is strongly related to the electrostatic charge, partition coefficients and dissociation constants of the herbicides. Biopolymer based membranes present novel systems for the removal of herbicides from contaminated water sources and hold great promise in the field of environmental science and engineering.

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

    PubMed

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

    2009-03-01

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

  2. Improving the controlled delivery formulations of caffeine in alginate hydrogel beads combined with pectin, carrageenan, chitosan and psyllium.

    PubMed

    Belščak-Cvitanović, Ana; Komes, Draženka; Karlović, Sven; Djaković, Senka; Spoljarić, Igor; Mršić, Gordan; Ježek, Damir

    2015-01-15

    Alginate-based blends consisting of carrageenan, pectin, chitosan or psyllium husk powder were prepared for assessment of the best formulation aimed at encapsulation of caffeine. Alginate-pectin blend exhibited the lowest viscosity and provided the smallest beads. Alginate-psyllium husk blend was characterised with higher viscosity, yielding the largest bead size and the highest caffeine encapsulation efficiency (83.6%). The release kinetics of caffeine indicated that the porosity of alginate hydrogel was not reduced sufficiently to retard the diffusion of caffeine from the beads. Chitosan coated alginate beads provided the most retarded release of caffeine in water. Morphological characteristics of beads encapsulating caffeine were adversely affected by freeze drying. Bitterness intensity of caffeine-containing beads in water was the lowest for alginate-psyllium beads and chitosan coated alginate beads. Higher sodium alginate concentration (3%) for production of hydrogel beads in combination with psyllium or chitosan coating would present the most favourable carrier systems for immobilization of caffeine.

  3. Microsphere based improved sunscreen formulation of ethylhexyl methoxycinnamate.

    PubMed

    Gogna, Deepak; Jain, Sunil K; Yadav, Awesh K; Agrawal, G P

    2007-04-01

    Polymethylmethacrylate (PMMA) microspheres of ethylhexyl methoxycinnamate (EHM) were prepared by emulsion solvent evaporation method to improve its photostability and effectiveness as sunscreening agent. Process parameters like stirring speed and aqueous polyvinyl alcohol (PVA) concentration were analyzed in order to optimize the formulations. Shape and surface morphology of the microspheres were examined using scanning electron microscopy. Particle size of the microspheres was determined using laser diffraction particle size analyzer. The PMMA microspheres of EHM were incorporated in water-removable cream base. The in vitro drug release of EHM in pH 7.4 was performed using dialysis membrane. Thin layer chromatography was performed to determine photostability of EHM inside the microspheres. The formulations were evaluated for sun protection factor (SPF) and minimum erythema dose (MED) in albino rats. Cream base formulation containing microspheres prepared using EHM:PMMA in ratio of 1:3 (C(3)) showed slowest drug (EHM) release and those prepared with EHM: PMMA in ratio of 1:1 showed fastest release. The cream base formulations containing EHM loaded microspheres had shown better SPF (more than 16.0) as compared to formulation C(d) that contained 3% free EHM as sunscreen agent and showed SPF 4.66. These studies revealed that the incorporation of EHM loaded PMMA microspheres into cream base had greatly increased the efficacy of sunscreen formulation approximately four times. Further, photostability was also shown to be improved in PMMA microspheres.

  4. Alginate hydrogel as a promising scaffold for dental-derived stem cells: an in vitro study.

    PubMed

    Moshaverinia, Alireza; Chen, Chider; Akiyama, Kentaro; Ansari, Sahar; Xu, Xingtian; Chee, Winston W; Schricker, Scott R; Shi, Songtao

    2012-12-01

    The objectives of this study were to: (1) develop an injectable and biodegradable scaffold based on oxidized alginate microbeads encapsulating periodontal ligament (PDLSCs) and gingival mesenchymal stem cells (GMSCs); and (2) investigate the stem cell viability, and osteogenic differentiation of the stem cells in vitro. Stem cells were encapsulated using alginate hydrogel. The stem cell viability, proliferation and differentiation to adipogenic and osteogenic tissues were studied. To investigate the expression of both adipogenesis and ontogenesis related genes, the RNA was extracted and RT-PCR was performed. The degradation behavior of hydrogel based on oxidized sodium alginate with different degrees of oxidation was studied in PBS at 37 °C as a function of time by monitoring the changes in weight loss. The swelling kinetics of alginate hydrogel was also investigated. The results showed that alginate is a promising candidate as a non-toxic scaffold for PDLSCs and GMSCs. It also has the ability to direct the differentiation of these stem cells to osteogenic and adipogenic tissues as compared to the control group in vitro. The encapsulated stem cells remained viable in vitro and both osteo-differentiated and adipo-differentiated after 4 weeks of culturing in the induction media. It was found that the degradation profile and swelling kinetics of alginate hydrogel strongly depends on the degree of oxidation showing its tunable chemistry and degradation rate. These findings demonstrate for the first time that immobilization of PDLSCs and GMSCs in the alginate microspheres provides a promising strategy for bone tissue engineering.

  5. The effect of formulation variables on the characteristics of insulin-loaded poly(lactic-co-glycolic acid) microspheres prepared by a single phase oil in oil solvent evaporation method.

    PubMed

    Hamishehkar, Hamed; Emami, Jaber; Najafabadi, Abdolhossein Rouholamini; Gilani, Kambiz; Minaiyan, Mohsen; Mahdavi, Hamid; Nokhodchi, Ali

    2009-11-01

    Biodegradable polymeric microspheres are ideal vehicles for controlled delivery applications of drugs, peptides and proteins. Amongst them, poly(lactic-co-glycolic acid) (PLGA) has generated enormous interest due to their favorable properties and also has been approved by FDA for drug delivery. Insulin-loaded PLGA microparticles were prepared by our developed single phase oil in oil (o/o) emulsion solvent evaporation technique. Insulin, a model protein, was successfully loaded into microparticles by changing experimental variables such as polymer molecular weight, polymer concentration, surfactant concentration and stirring speed in order to optimize process variables on drug encapsulation efficiency, release rates, size and size distribution. A 2(4) full factorial design was employed to evaluate systematically the combined effect of variables on responses. Scanning electron microscope (SEM) confirmed spherical shapes, smooth surface morphology and microsphere structure without aggregation. FTIR and DSC results showed drug-polymer interaction. The encapsulation efficiency of insulin was mainly influenced by surfactant concentration. Moreover, polymer concentration and polymer molecular weight affected burst release of drug and size characteristics of microspheres, respectively. It was concluded that using PLGA with higher molecular weight, high surfactant and polymer concentrations led to a more appropriate encapsulation efficiency of insulin with low burst effect and desirable release pattern.

  6. Preparation and retention mechanism study of graphene and graphene oxide bonded silica microspheres as stationary phases for high performance liquid chromatography.

    PubMed

    Zhang, Xiaoqiong; Chen, Sha; Han, Qiang; Ding, Mingyu

    2013-09-13

    Graphene oxide (GO) bonded stationary phase for high performance liquid chromatography (HPLC) was fabricated by coating GO sheets onto aminosilica microspheres via covalent coupling. Graphene (G) functionalized HPLC stationary phase was then prepared through hydrazine reduction of GO bonded silica (GO@SiO2) composite, which was the first example of using graphene as stationary-phase component for HPLC. Effective separations of the tested neutral and polar compounds on both GO@SiO2 and graphene bonded silica (G@SiO2) columns were achieved under the optimal experimental conditions. Compared with commercial C18 column, the different chromatographic performances of GO and graphene bonded columns were ascribed to their unique retention mechanisms. The polyaromatic scaffold of GO and graphene gives π-π stacking property and hydrophobic effect, and other retention mechanisms, such as π-π electron-donor-acceptor (EDA) interaction for the separation of nitroaromatic compounds and hydrogen bonding for hydroxyl and amino compounds, may also be taken into consideration. Experimental results indicated that the mixed-mode retention mechanism can facilitate the separation of analytes with similar hydrophobicity, which is a unique property compared with C18 column. Additionally, G@SiO2 showed higher affinity to aromatic analytes in contrast with GO@SiO2 and its retention mechanism was not consistent with the typical reversed phase behavior. The separation of aromatic compounds on G@SiO2 column relies primarily on the π-π stacking interaction and then the hydrophobicity, while the two interactions have equal shares on GO@SiO2 column.

  7. Dental mesenchymal stem cells encapsulated in an alginate hydrogel co-delivery microencapsulation system for cartilage regeneration.

    PubMed

    Moshaverinia, Alireza; Xu, Xingtian; Chen, Chider; Akiyama, Kentaro; Snead, Malcolm L; Shi, Songtao

    2013-12-01

    Dental-derived mesenchymal stem cells (MSCs) are promising candidates for cartilage regeneration, with a high capacity for chondrogenic differentiation. This property helps make dental MSCs an advantageous therapeutic option compared to current treatment modalities. The MSC delivery vehicle is the principal determinant for the success of MSC-mediated cartilage regeneration therapies. The objectives of this study were to: (1) develop a novel co-delivery system based on TGF-β1 loaded RGD-coupled alginate microspheres encapsulating periodontal ligament stem cells (PDLSCs) or gingival mesenchymal stem cells (GMSCs); and (2) investigate dental MSC viability and chondrogenic differentiation in alginate microspheres. The results revealed the sustained release of TGF-β1 from the alginate microspheres. After 4 weeks of chondrogenic differentiation in vitro, PDLSCs and GMSCs as well as human bone marrow mesenchymal stem cells (hBMMSCs) (as positive control) revealed chondrogenic gene expression markers (Col II and Sox-9) via qPCR, as well as matrix positively stained by Toluidine Blue and Safranin-O. In animal studies, ectopic cartilage tissue regeneration was observed inside and around the transplanted microspheres, confirmed by histochemical and immunofluorescent staining. Interestingly, PDLSCs showed more chondrogenesis than GMSCs and hBMMSCs (p<0.05). Taken together, these results suggest that RGD-modified alginate microencapsulating dental MSCs make a promising candidate for cartilage regeneration. Our results highlight the vital role played by the microenvironment, as well as value of presenting inductive signals for viability and differentiation of MSCs.

  8. Towards Monodispersed Polymer Microspheres

    NASA Astrophysics Data System (ADS)

    Senuma, Yoshinori; Hilborn, Jons

    1998-03-01

    Uniform polymer microspheres prepared by Spinning Disk Atomization Our spinning disk atomization (SDA) can, relative to other existing techniques, produce micron-sized particles of very narrow size distribution. Around the edge of the disk, small teeth channel the flow into identical droplets that are flung off over the disk rim. These solidify during flight to form spherical particles. Applications for spheres produced by SDA can be found in areas such as adhesives, powder coatings, food, biomedical use, drug delivery systems, etc. We have atomized polyethyleneglycol into very narrowly dispersed microspheres ranging from 50 to 500 =B5m. The aim of this work is to model the droplet formation occurring at the rim of the spinning disk in order to better understand the experimental results. The viscosity contribution in the fluid breakup is qualitatively analyzed and is adapted to the theoretical model to show how it affects the droplet size. We have used the pendant drop model (Ramesh Babu, S. Journal of Colloid and Interface Science 116, 350-372 (1987).) for spinning disk atomization to describe the drop-shape evolution during growth.

  9. Preparation of Fe3O4@C@PANI magnetic microspheres for the extraction and analysis of phenolic compounds in water samples by gas chromatography-mass spectrometry.

    PubMed

    Meng, Jiaoran; Shi, Chenyi; Wei, Biwen; Yu, Wenjia; Deng, Chunhui; Zhang, Xiangmin

    2011-05-20

    In this work, core-shell structure Fe(3)O(4)@C@polyaniline magnetic microspheres were synthesized using simple hydrothermal reactions. The carbon-coated magnetic microspheres (Fe(3)O(4)@C) were first synthesized by a hydrothermal reaction, and then aniline was polymerized on the magnetic core via another hydrothermal reaction. Then, the obtained Fe(3)O(4)@C@polyaniline magnetic microspheres were applied as magnetic adsorbents for the extraction of aromatic molecules due to π-π interactions between polyaniline shell and aromatic compounds. In our study, five kinds of phenols including phenol, 2,4-dichlorophenol (DCP), 2,4,5-trichlorophenol (TCP), pentachlorophenol (PCP) and bisphenol A (BPA) were selected as the model analytes to verify the extraction ability of Fe(3)O(4)@C@PANI microspheres. After derivatization, the phenols were detected using gas chromatography-mass spectrometry (GC-MS). The dominant parameters affecting enrichment efficiency were investigated and optimized. Under the optimal conditions, the proposed method was evaluated, and applied to the analysis of phenols in real water samples. The results demonstrated that our proposed method based on Fe(3)O(4)@C@polyaniline magnetic microspheres had good linearity (r(2)>0.991), and limits of quantification (2.52-29.7 ng/mL), high repeatability (RSD<13.1%) and good recovery (85.3-110.6%).

  10. Photocatalytic Activities of Copper Doped Cadmium Sulfide Microspheres Prepared by a Facile Ultrasonic Spray-Pyrolysis Method.

    PubMed

    Su, Jinzhan; Zhang, Tao; Li, Yufeng; Chen, Yubin; Liu, Maochang

    2016-06-15

    Ultrasonic spray pyrolysis is a superior method for preparing and synthesizing spherical particles of metal oxide or sulfide semiconductors. Cadmium sulfide (CdS) photocatalysts with different sizes and doped-CdS with different dopants and doping levels have been synthesized to study their properties of photocatalytic hydrogen production from water. The CdS photocatalysts were characterized with scanning electron microscopy (SEM), X-ray fluorescence-spectrometry (XRF), UV-Vis absorption spectra and X-ray diffraction (XRD) to study their morphological and optical properties. The sizes of the prepared CdS particles were found to be proportional to the concentration of the metal nitrates in the solution. The CdS photocatalyst with smaller size showed a better photocatalytic activity. In addition, Cu doped CdS were also deposited and their photocatalytic activities were also investigated. Decreased bandgaps of CdS synthesized with this method were found and could be due to high density surface defects originated from Cd vacancies. Incorporating the Cu elements increased the bandgap by taking the position of Cd vacancies and reducing the surface defect states. The optimal Cu-doped level was found to be 0.5 mol % toward hydrogen evolution from aqueous media in the presence of sacrificial electron donors (Na₂S and Na₂SO₃) at a pH of 13.2. This study demonstrated that ultrasonic spray pyrolysis is a feasible approach for large-scale photocatalyst synthesis and corresponding doping modification.

  11. Effect of the gelation process on the production of alginate microbeads by microfluidic chip technology.

    PubMed

    Capretto, Lorenzo; Mazzitelli, Stefania; Balestra, Cosimo; Tosi, Azzura; Nastruzzi, Claudio

    2008-04-01

    The present paper reports the production of Ba-alginate microspheres by microfluidic chip technology. The general production strategy is based on the formation of an alginate multiphase flow by a 'Y' junction squeezing mechanism. Special emphasis is given to the relationship existing between the gelation process and the final morphological characteristics of the produced microbeads. A series of different gelation strategies, namely: 'external gelation', 'internal gelation' and 'partial gelation' were compared in terms of size, size distribution and morphology of the produced microbeads.

  12. Effect of alginate composition on profile release and characteristics of chitosan-alginate microparticles loaded with mangosteen extract

    NASA Astrophysics Data System (ADS)

    Mulia, Kamarza; Halimah, Nur; Krisanti, Elsa

    2017-03-01

    Preparation of mangostin-loaded chitosan-alginate microparticles, chemical and physical characterization of the particles, and mangostin release profiles, are described herein. Mangostin rich fraction was obtained from Garcinia mangostana L. pericarp by extraction followed by fractionation. Mangostin-loaded chitosan-alginate microparticles were prepared by ionic gelation method using tripolyphosphate as the linking agent and various concentration of alginate. Mangostin was effectively loaded in all microparticle formulations, resulting in ˜97% encapsulation efficiencies. The loading of mangostin and the in-vitro release profiles in simulated gastrointestinal fluids were affected by the chitosan to alginate ratios used in the preparation of the microparticles. Increased alginate concentration resulted in lowered release of mangostin from microparticles immersed in simulated gastric fluid (pH 1.2) up to two hours. Low release of mangostin in acidic fluid but high release in simulated colon fluid, indicated that the chitosan-alginate microparticles are prospective carrier for extended release of active compound in gastrointestinal system.

  13. Pluronic F127/chitosan blend microspheres for mucoadhesive drug delivery

    NASA Astrophysics Data System (ADS)

    Gu, W. Z.; Hu, X. F.

    2017-01-01

    Pluronic F127/chitosan blend microspheres were prepared via emulsification and cross-linking process using glutaraldehyde as a cross-linker. Compared with chitosan microspheres fabricated under the same experimental conditions, blend microspheres exhibited better physical stability and higher swelling capacity. Puerarin, a traditional Chinese medicine, was incorporated into microparticlesas the model drug. The in vitro release of puerarin from blend microspheres was reduced because of the improved compatibility of the drug with the matrices. According to the results from in vitro adhesion experiments, mucoadhesive behavior of blend microspheres on a mucosa-like surface was similar to that of chitosan microspheres, despite their good ability of anti-protein absorption in solution.

  14. Preparation of magnetic core mesoporous shell microspheres with C18-modified interior pore-walls for fast extraction and analysis of phthalates in water samples.

    PubMed

    Li, Zhongbo; Huang, Danni; Fu, Chinfai; Wei, Biwen; Yu, Wenjia; Deng, Chunhui; Zhang, Xiangmin

    2011-09-16

    In this study, core-shell magnetic mesoporous microspheres with C18-functionalized interior pore-walls were synthesized through coating Fe(3)O(4) microspheres with a mesoporous inorganic-organic hybrid layer with a n-octadecyltriethoxysilane (C18TES) and tetraethyl orthosilicate (TEOS) as the silica source and cetyltrimethylammonia bromide (CTAB) as a template. The obtained C18-functionalized Fe(3)O(4)@mSiO(2) microspheres possess numerous C18 groups anchored in the interior pore-walls, large surface area (274.7 m(2)/g, high magnetization (40.8 emu/g) and superparamagnetism, uniform mesopores (4.1 nm), which makes them ideal absorbents for simple, fast, and efficient extraction and enrichment of hydrophobic organic compounds in water samples. Several kinds of phthalates were used as the model hydrophobic organic compounds to systematically evaluate the performance of the C18-functionalized Fe(3)O(4)@mSiO(2) microspheres in extracting hydrophobic molecules by using a gas chromatography-mass spectrometry. Various parameters, including eluting solvent, the amounts of absorbents, extraction time and elution time were optimized. Hydrophobic extraction was performed in the interior pore of magnetic mesoporous microspheres, and the materials had the anti-interference ability to macromolecular proteins, which was also investigated in the work. Under the optimized conditions, C18-functionalized Fe(3)O(4)@mSiO(2) microspheres were successfully used to analyze the real water samples. The results indicated that this novel method was fast, convenient and efficient for the target compounds and could avoid being interfered by macromolecules.

  15. Pectin/zein microspheres as a sustained drug delivery system

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A series of microspheres were prepared from pectins and corn proteins from various sources in the presence of the divalent ions calcium or zinc. The results showed that the yield of microsphere and the efficiency of drug incorporation were dependent on the type and ratio of biopolymers, the size of ...

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

    PubMed

    Kamali Moghaddam, Meghdad; Mortazavi, Sayed Majid

    2015-01-01

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

  17. Quantitative Assessment of Islets of Langerhans Encapsulated in Alginate

    PubMed Central

    Johnson, Amy S.; O'Sullivan, Esther; D'Aoust, Laura N.; Omer, Abdulkadir; Bonner-Weir, Susan; Fisher, Robert J.; Weir, Gordon C.

    2011-01-01

    Improved methods have recently been developed for assessing islet viability and quantity in human islet preparations for transplantation, and these measurements have proven useful for predicting transplantation outcome. The objectives of this study were to adapt these methods for use with microencapsulated islets, to verify that they provide meaningful quantitative measurements, and to test them with two model systems: (1) barium alginate and (2) barium alginate containing a 70% (w/v) perfluorocarbon (PFC) emulsion, which presents challenges to use of these assays and is of interest in its own right as a means for reducing oxygen supply limitations to encapsulated tissue. Mitochondrial function was assessed by oxygen consumption rate measurements, and the analysis of data was modified to account for the increased solubility of oxygen in the PFC-alginate capsules. Capsules were dissolved and tissue recovered for nuclei counting to measure the number of cells. Capsule volume was determined from alginate or PFC content and used to normalize measurements. After low oxygen culture for 2 days, islets in normal alginate lost substantial viable tissue and displayed necrotic cores, whereas most of the original oxygen consumption rate was recovered with PFC alginate, and little necrosis was observed. All nuclei were recovered with normal alginate, but some nuclei from nonrespiring cells were lost with PFC alginate. Biocompatibility tests revealed toxicity at the islet periphery associated with the lipid emulsion used to provide surfactants during the emulsification process. We conclude that these new assay methods can be applied to islets encapsulated in materials as complex as PFC-alginate. Measurements made with these materials revealed that enhancement of oxygen permeability of the encapsulating material with a concentrated PFC emulsion improves survival of encapsulated islets under hypoxic conditions, but reformulation of the PFC emulsion is needed to reduce toxicity

  18. Microspheres and nanoparticles from ultrasound

    NASA Astrophysics Data System (ADS)

    Suh, Won Hyuk

    Improved preparations of various examples of monodispersed, porous, hollow, and core-shell metal and semiconductor nanoparticles or nanowires have been developed. Now titania microspheres and nanoparticles and silica microspheres can be synthesized using an inexpensive high frequency (1.7 MHz) ultrasonic generator (household humidifier; ultrasonic spray pyrolysis; USP). Morphology and pore size of titania microspheres were controlled by the silica to Ti(IV) ratio and silica particle size. Fine tuning the precursor ratio affords sub-50 nm titania nanoparticles as well. In terms of silica microspheres, morphology was controlled by the silica to organic monomer ratio. In liquids irradiated with high intensity ultrasound (20 kHz; HIUS), acoustic cavitation produces high energy chemistry through intense local heating inside the gas phase of collapsing bubbles in the liquid. HIUS and USP confine the chemical reactions to isolated sub-micron reaction zones, but sonochemistry does so in a heated gas phase within a liquid, while USP uses a hot liquid droplet carried by a gas flow. Thus, USP can be viewed as a method of phase-separated synthesis using submicron-sized droplets as isolated chemical reactors for nanomaterial synthesis. While USP has been used to create both titania and silica spheres separately, there are no prior reports of titania-silica composites. Such nanocomposites of metal oxides have been produced, and by further manipulation, various porous structures with fascinating morphologies were generated. Briefly, a precursor solution was nebulized using a commercially available household ultrasonic humidifier (1.7 MHz ultrasound generator), and the resulting mist was carried in a gas stream of air through a quartz glass tube in a hot furnace. After exiting the hot zone, these microspheres are porous or hollow and in certain cases magnetically responsive. In the case of titania microspheres, they are rapidly taken up into the cytoplasm of mammalian cells and

  19. Ag/α-Fe{sub 2}O{sub 3} hollow microspheres: Preparation and application for hydrogen peroxide detection

    SciTech Connect

    Kang, Xinyuan; Wu, Zhiping; Liao, Fang Zhang, Tingting; Guo, Tingting

    2015-09-15

    In this paper, we demonstrated a simple approach for preparing α-Fe{sub 2}O{sub 3} hollow spheres by mixing ferric nitrate aqueous and glucose in 180 °C. The glucose was found to act as a soft template in the process of α-Fe{sub 2}O{sub 3} hollow spheres formation. Ag/α-Fe{sub 2}O{sub 3} hollow nanocomposite was obtained under UV irradiation without additional reducing agents or initiators. Synthesized Ag/α-Fe{sub 2}O{sub 3} hollow composites exhibited remarkable catalytic performance toward H{sub 2}O{sub 2} reduction. The electrocatalytic activity mechanism of Ag/α-Fe{sub 2}O{sub 3}/GCE were discussed toward the reduction of H{sub 2}O{sub 2} in this paper. - Graphical abstract: Glucose is carbonized as carbon balls in the 180 °C hydrothermal carbonization process, which plays a role of a soft template. Carbon spherical shell is rich in many hydroxyls, which have good hydrophilicity and surface reactivity. When Fe(NO{sub 3}){sub 3} is added to the aqueous solution of Glucose, the hydrophilic -OH will adsorb Fe{sup 3+} to form coordination compound by coordination bond. α-FeOOH is formed on the surface of carbon balls by hydrothermal reaction. After calcination at 500 °C, carbon spheres react with oxygen to form carbon dioxide, which disappears in the air. Meanwhile α-FeOOH is calcined to form α-Fe{sub 2}O{sub 3} hollow spheres.

  20. 21 CFR 184.1610 - Potassium alginate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Potassium alginate. 184.1610 Section 184.1610 Food... GRAS § 184.1610 Potassium alginate. (a) Potassium alginate (CAS Reg. No. 9005-36-1) is the potassium salt of alginic acid, a natural polyuronide constituent of certain brown algae. Potassium alginate...

  1. 21 CFR 184.1724 - Sodium alginate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Sodium alginate. 184.1724 Section 184.1724 Food and... Substances Affirmed as GRAS § 184.1724 Sodium alginate. (a) Sodium alginate (CAS Reg. No. 9005-38-3) is the sodium salt of alginic acid, a natural polyuronide constituent of certain brown algae. Sodium alginate...

  2. In vitro evaluation of alginate/halloysite nanotube composite scaffolds for tissue engineering.

    PubMed

    Liu, Mingxian; Dai, Libing; Shi, Huizhe; Xiong, Sheng; Zhou, Changren

    2015-04-01

    In this study, a series of alginate/halloysite nanotube (HNTs) composite scaffolds were prepared by solution-mixing and freeze-drying method. HNTs are incorporated into alginate to improve both the mechanical and cell-attachment properties of the scaffolds. The interfacial interactions between alginate and HNTs were confirmed by the atomic force microscope (AFM), transmission electron microscope (TEM) and FTIR spectroscopy. The mechanical, morphological, and physico-chemical properties of the composite scaffolds were investigated. The composite scaffolds exhibit significant enhancement in compressive strength and compressive modulus compared with pure alginate scaffold both in dry and wet states. A well-interconnected porous structure with size in the range of 100-200μm and over 96% porosity is found in the composite scaffolds. X-ray diffraction (XRD) result shows that HNTs are uniformly dispersed and partly oriented in the composite scaffolds. The incorporation of HNTs leads to increase in the scaffold density and decrease in the water swelling ratio of alginate. HNTs improve the stability of alginate scaffolds against enzymatic degradation in PBS solution. Thermogravimetrica analysis (TGA) shows that HNTs can improve the thermal stability of the alginate. The mouse fibroblast cells display better attachment to the alginate/HNT composite than those to the pure alginate, suggesting the good cytocompatibility of the composite scaffolds. Alginate/HNT composite scaffolds exhibit great potential for applications in tissue engineering.

  3. Optimization of sustained release aceclofenac microspheres using response surface methodology.

    PubMed

    Deshmukh, Rameshwar K; Naik, Jitendra B

    2015-03-01

    Polymeric microspheres containing aceclofenac were prepared by single emulsion (oil-in-water) solvent evaporation method using response surface methodology (RSM). Microspheres were prepared by changing formulation variables such as the amount of Eudragit® RS100 and the amount of polyvinyl alcohol (PVA) by statistical experimental design in order to enhance the encapsulation efficiency (E.E.) of the microspheres. The resultant microspheres were evaluated for their size, morphology, E.E., and in vitro drug release. The amount of Eudragit® RS100 and the amount of PVA were found to be significant factors respectively for determining the E.E. of the microspheres. A linear mathematical model equation fitted to the data was used to predict the E.E. in the optimal region. Optimized formulation of microspheres was prepared using optimal process variables setting in order to evaluate the optimization capability of the models generated according to IV-optimal design. The microspheres showed high E.E. (74.14±0.015% to 85.34±0.011%) and suitably sustained drug release (minimum; 40% to 60%; maximum) over a period of 12h. The optimized microspheres formulation showed E.E. of 84.87±0.005 with small error value (1.39). The low magnitudes of error and the significant value of R(2) in the present investigation prove the high prognostic ability of the design. The absence of interactions between drug and polymers was confirmed by Fourier transform infrared (FTIR) spectroscopy. Differential scanning calorimetry (DSC) and X-ray powder diffractometry (XRPD) revealed the dispersion of drug within microspheres formulation. The microspheres were found to be discrete, spherical with smooth surface. The results demonstrate that these microspheres could be promising delivery system to sustain the drug release and improve the E.E. thus prolong drug action and achieve the highest healing effect with minimal gastrointestinal side effects.

  4. Alginate Lyase Promotes Diffusion of Aminoglycosides through the Extracellular Polysaccharide of Mucoid Pseudomonas aeruginosa

    PubMed Central

    Hatch, Richard A.; Schiller, Neal L.

    1998-01-01

    We demonstrated that a 2% suspension of Pseudomonas aeruginosa alginate completely blocked the diffusion of gentamicin and tobramycin, but not that of carbenicillin, illustrating how alginate production can help protect P. aeruginosa growing within alginate microcolonies in patients with cystic fibrosis (CF) from the effects of aminoglycosides. This aminoglycoside diffusion barrier was degraded with a semipurified preparation of P. aeruginosa alginate lyase, suggesting that this enzyme deserves consideration as an adjunctive agent for CF patients colonized by mucoid strains of P. aeruginosa. PMID:9559826

  5. Transition-metal-free synthesis of supramolecular ionic alginate-based polyurethanes.

    PubMed

    Daemi, Hamed; Barikani, Mehdi; Sardon, Haritz

    2017-02-10

    Novel high molecular weight alginate-based supramolecular ionic polyurethane (SPU) networks were prepared via the reaction of chemically modified polyanionic alginate and isocyanate-terminated cationic oligourethanes under transition-metal-free conditions. Alginate, a naturally occurring polyanionic carbohydrate diol possessing carboxylate groups, was considered as both chain extender and the anionic part of SPU network. The tailor-made, ionically crosslinked linear alginate-based SPUs illustrated superior thermal stability with a decomposition temperature around 500°C at 10% weight loss which specializes them as highly thermally stable, wonder materials compared to the today's high-tech products.

  6. Immobilization of silver nanoparticles on silica microspheres

    NASA Astrophysics Data System (ADS)

    Huang, Chih-Kai; Chen, Chia-Yin; Han, Jin-Lin; Chen, Chii-Chang; Jiang, Meng-Dan; Hsu, Jen-Sung; Chan, Chia-Hua; Hsieh, Kuo-Huang

    2010-01-01

    The silver nanoparticles (Ag NPs) have been immobilized onto silica microspheres through the adsorption and subsequent reduction of Ag+ ions on the surfaces of the silica microspheres. The neat silica microspheres that acted as the core materials were prepared through sol-gel processing; their surfaces were then functionalized using 3-mercaptopropyltrimethoxysilane (MPTMS). The major aims of this study were to immobilize differently sized Ag particles onto the silica microspheres and to understand the mechanism of formation of the Ag nano-coatings through the self-assembly/adsorption behavior of Ag NPs/Ag+ ions on the silica spheres. The obtained Ag NP/silica microsphere conglomerates were characterized by field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), and energy-dispersive spectroscopy (EDS). Their electromagnetic wave shielding effectiveness were also tested and studied. The average particle size of the obtained Ag NPs on the silica microsphere was found that could be controllable (from 2.9 to 51.5 nm) by adjusting the ratio of MPTMS/TEOS and the amount of AgNO3.

  7. Fabrication of patterned calcium cross-linked alginate hydrogel films and coatings through reductive cation exchange.

    PubMed

    Bruchet, Marion; Melman, Artem

    2015-10-20

    Calcium cross-linked alginate hydrogels are widely used in targeted drug delivery, tissue engineering, wound treatment, and other biomedical applications. We developed a method for preparing homogeneous alginate hydrogels cross-linked with Ca(2+) cations using reductive cation exchange in homogeneous iron(III) cross-linked alginate hydrogels. Treatment of iron(III) cross-linked alginate hydrogels with calcium salts and sodium ascorbate results in reduction of iron(III) cations to iron(II) that are instantaneously replaced with Ca(2+) cations, producing homogeneous ionically cross-linking hydrogels. Alternatively, the cation exchange can be performed by photochemical reduction in the presence of calcium chloride using a sacrificial photoreductant. This approach allows fabrication of patterned calcium alginate hydrogels through photochemical patterning of iron(III) cross-linked alginate hydrogel followed by the photochemical reductive exchange of iron cations to calcium.

  8. Biodegradable polymer-silica xerogel composite microspheres for controlled release of gentamicin.

    PubMed

    Xue, J M; Tan, C H; Lukito, D

    2006-08-01

    Single and double layered composite microspheres were prepared by encapsulating gentamicin-loaded silica xerogels with biodegradable PLGA polymers (poly(DL-lactide-co-glycolide)). The in vitro drug release properties of both the composite microspheres were investigated. The single layered composite microspheres showed a high initial burst, followed by two sustained release stages lasting for approximately 6 weeks. The two sustained release stages of the single layered composite microspheres could be attributed to the swelling and bulk erosion of the polymer encapsulations, respectively. In comparison with the single layered composite microspheres, the double layered composite microspheres realized a much reduced initial burst together with three sustained release stages. The whole release period of the double layered composite microspheres could last more than 9 weeks. These distinct behaviors make the double layered composite microspheres promising as a new drug release material for localized drug delivery applications.

  9. A reproducible accelerated in vitro release testing method for PLGA microspheres.

    PubMed

    Shen, Jie; Lee, Kyulim; Choi, Stephanie; Qu, Wen; Wang, Yan; Burgess, Diane J

    2016-02-10

    The objective of the present study was to develop a discriminatory and reproducible accelerated in vitro release method for long-acting PLGA microspheres with inner structure/porosity differences. Risperidone was chosen as a model drug. Qualitatively and quantitatively equivalent PLGA microspheres with different inner structure/porosity were obtained using different manufacturing processes. Physicochemical properties as well as degradation profiles of the prepared microspheres were investigated. Furthermore, in vitro release testing of the prepared risperidone microspheres was performed using the most common in vitro release methods (i.e., sample-and-separate and flow through) for this type of product. The obtained compositionally equivalent risperidone microspheres had similar drug loading but different inner structure/porosity. When microsphere particle size appeared similar, porous risperidone microspheres showed faster microsphere degradation and drug release compared with less porous microspheres. Both in vitro release methods investigated were able to differentiate risperidone microsphere formulations with differences in porosity under real-time (37 °C) and accelerated (45 °C) testing conditions. Notably, only the accelerated USP apparatus 4 method showed good reproducibility for highly porous risperidone microspheres. These results indicated that the accelerated USP apparatus 4 method is an appropriate fast quality control tool for long-acting PLGA microspheres (even with porous structures).

  10. Preparation of hydroxyapatite/collagen injectable bone paste with an anti-washout property utilizing sodium alginate. Part 1: influences of excess supplementation of calcium compounds.

    PubMed

    Sato, Taira; Kikuchi, Masanori; Aizawa, Mamoru

    2017-03-01

    The anti-washout property, viscosity, and cytocompatibility to an osteoblastic cell line, MG-63, of anti-washout pastes were investigated. Mixing a hydroxyapatite/collagen bone-like nanocomposite (HAp/Col), an aqueous solution of sodium alginate (Na-Alg), which is a paste hardening and lubricant agent, and supplementation of calcium carbonate or calcium citrate (Ca-Cit) as a calcium resource for the hardening reaction realized an injectable bone paste. Adding Ca-Cit at a concentration greater than eight times the Ca(2+) ion concentration to Na-Alg improved the anti-washout property. Although the viscosity test indicated a gradual increase in the paste viscosity as the calcium compounds increased, pastes with excess supplementation of calcium compounds exhibited injectability through a syringe with a 1.8 mm inner diameter, realizing an injectable bone filler. Furthermore, the anti-washout pastes with Ca-Cit had almost the same cell proliferation rate as that of the HAp/Col dense body. Therefore, HAp/Col injectable anti-washout pastes composed of the HAp/Col, Na-Alg, and Ca-Cit are potential candidates for bioresorbable bone filler pastes.

  11. Silk fibroin/sodium alginate composite nano-fibrous scaffold prepared through thermally induced phase-separation (TIPS) method for biomedical applications.

    PubMed

    Zhang, Haiping; Liu, Xiaotian; Yang, Mingying; Zhu, Liangjun

    2015-10-01

    To mimic the natural fibrous structure of the tissue extracellular matrix, a nano-fibrous silk fibroin (SF)/sodium alginate (SA) composite scaffold was fabricated by a thermally-induced phase-separation method. The effects of SF/SA ratio on the structure and the porosity of the composite scaffolds were examined. Scanning electron microscopy and porosity results showed that the 5SF/1SA and 3SF/1SA scaffolds possessed an excellent nano-fibrous structure and a porosity of more than 90%. Fourier transform infrared, X-ray diffraction, and differential scanning calorimetry results indicated the physical interaction between SF and SA molecules and their good compatibility in the 5SF/1SA and 3SF/1SA scaffolds, whereas they showed less compatibility in the 1SF/1SA scaffold. Cell culture results showed that MG-63 cells can attach and grow well on the surface of the SF/SA scaffolds. The nano-fibrous SF/SA scaffold can be potentially used in tissue engineering.

  12. Stability testing of alginate-chitosan films.

    PubMed

    Rabisková, Miloslava; Dvorácková, Katerina; Kofronvá, Lenka

    2012-02-01

    Pellets containing rutin prepared by the extrusion/spheronization method were coated with sodium alginate-chitosan film. Important quality parameters in the pellets before coating were determined, and after coating the dissolution profiles of the drug were evaluated in dissolution media of the pH corresponding to the conditions in the gastrointestinal tract. Samples of coated pellets were located in the boxes for stability testing under different conditions, i.e. 25 degrees C and 60% of relative humidity (RH); 30 degrees C and 65% RH and 40 degrees C and 75% RH. After 1, 3, 6, 9 and 12 months (or 1, 3 and 6 months), the dissolution test was repeated and compared with the original profiles using similarity factors. All similarity factor values above 50 indicate excellent stability of alginate-chitosan films.

  13. Facile preparation of novel dandelion-like Fe-doped NiCo2O4 microspheres@nanomeshes for excellent capacitive property in asymmetric supercapacitors

    NASA Astrophysics Data System (ADS)

    Liu, Li; Zhang, Huijuan; Fang, Ling; Mu, Yanping; Wang, Yu

    2016-09-01

    In this work, we successfully synthesized the dandelion-like Fe-doped NiCo2O4 microspheres@nanomeshes (Fe-NCO-M@N-1h) using a facile hydrothermal method, followed by calcinations. In the unique structure, numerous nanoneedles radially grow on the surface of microsphere and some porous nanomeshes orderly develop in the inside of microsphere, therefore dandelion-like Fe-NCO-M@N-1h displays large specific surface area (101.15 m2 g-1) and more active sites. Electrochemical properties of the Fe-NCO-M@N-1h have been tested for symmetric supercapacitors (SCs) and asymmetric supercapacitors (ASCs). Benefiting from the structural advantages, Fe-NCO-M@N-1h electrode exhibits outstanding capacitive behaviors, such as the desirable specific capacitance and eminent rate performance (2237 and 1810 F g-1 at the current densities of 1 and 20 A g-1, respectively) and remarkable cycling performance (95.8% retention after 4500 cycles). Besides, a Fe-NCO-M@N-1h//AC-ASCs device has been constructed successfully, presenting the highest energy density of 46.68 Wh kg-1. The results indicate that the Fe-NCO-M@N-1h is a potential material for SCs.

  14. Microencapsulation of a probiotic and prebiotic in alginate-chitosan capsules improves survival in simulated gastro-intestinal conditions.

    PubMed

    Chávarri, María; Marañón, Izaskun; Ares, Raquel; Ibáñez, Francisco C; Marzo, Florencio; Villarán, María del Carmen

    2010-08-15

    Chitosan was used as a coating material to improve encapsulation of a probiotic and prebiotic in calcium alginate beads. Chitosan-coated alginate microspheres were produced to encapsulate Lactobacillus gasseri (L) and Bifidobacterium bifidum (B) as probiotics and the prebiotic quercetin (Q) with the objective of enhancing survival of the probiotic bacteria and keeping intact the prebiotic during exposure to the adverse conditions of the gastro-intestinal tract. The encapsulation yield for viable cells for chitosan-coated alginate microspheres with quercetin (L+Q and B+Q) was very low. These results, together with the study about the survival of microspheres with quercetin during storage at 4 degrees C, demonstrated that probiotic bacteria microencapsulated with quercetin did not survive. Owing to this, quercetin and L. gasseri or B. bifidum were microencapsulated separately. Microencapsulated L. gasseri and microencapsulated B. bifidum were resistant to simulated gastric conditions (pH 2.0, 2h) and bile solution (3%, 2h), resulting in significantly (p<0.05) improved survival when compared with free bacteria. This work showed that the microencapsulation of L. gasseri and B. bifidum with alginate and a chitosan coating offers an effective means of delivery of viable bacterial cells to the colon and maintaining their survival during simulated gastric and intestinal juice.

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

    PubMed

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

    2007-09-01

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

  16. Understanding Alginate Gel Development for Bioclogging and Biogeophysical Experiments

    NASA Astrophysics Data System (ADS)

    Brown, I.; Atekwana, E. A.; Abdel Aal, G. Z.; Atekwana, E. A.; Sarkisova, S.; Patrauchan, M.

    2012-12-01

    Bioremediation strategies to mitigate the transport of heavy metals and radionuclides in subsurface sediments have largely targeted to increase the mobility and/or solubility of these compounds by the stimulation of biogeochemical activity of the metal- and sulfate-reducing bacteria. The latter secrete and/or release out diverse biochemical molecule including, first of all, organic acids and biopolymers such as alginic acid, proteins and DNA. Alginate gel is one of the major components determining the structure of biofilm which causes clogging in porous media. Biopolymers composing biofilm having, at least, two main functions: to be a scaffold for a microbial biofilm, and to regulate the exchange of metabolites and ions between an environment and bacterial cells. Additionally, the accumulation of biopolymers and a matured biofilm within porous media was shown to contribute to a detectable biogeophysical signal, spectral induced polarization (SIP), in particular. Our objective is to understand the role of different biofilm components on the SIP response as the latter has been proposed as a non-invasive tool to monitor biofilm development and rate of clogging in the subsurface. Understanding the process of alginate gel development may aid in the understanding of the fate and transport of mineralized heavy metals and radionuclides in contaminated soils. Here we describe the reciprocal relationship between environmental chemistry and alginate gel development. Commercial (Sigma) alginic acid (AA) was used as a substratum for the preparation of a model gel. AA was solubilized by adjusting solutions with pH up to 4 with 0.1 NaOH. Both Ca(OH)2 or CaCl2 were used to initiate the gelation of alginate. pH, fluid conductivity, soluble Ca2+ concentration, and a yield of gelated alginate were monitored in both liquid and porous media after the interaction of calcium compounds with alginate. This study confirms the critical role of Ca2+ for alginate gelation, biofilm development

  17. Enzyme immobilization in novel alginate-chitosan core-shell microcapsules.

    PubMed

    Taqieddin, Ehab; Amiji, Mansoor

    2004-05-01

    Alginate-chitosan core-shell microcapsules were prepared in order to develop a biocompatible matrix for enzyme immobilization, where the protein is retained either in a liquid or solid core and the shell allows permeability control over substrates and products. The permeability coefficients of different molecular weight compounds (vitamin B2, vitamin B12, and myoglobin) were determined through sodium tripolyphosphate (Na-TPP)-crosslinked chitosan membrane. The microcapsule core was formed by crosslinking sodium alginate with either calcium or barium ions. The crosslinked alginate core was uniformly coated with a chitosan layer and crosslinked with Na-TPP. In the case of calcium alginate, the phosphate ions of Na-TPP were able to extract the calcium ions from alginate and liquefy the core. A model enzyme, beta-galactosidase, was immobilized in the alginate core and the catalytic activity was measured with o-nitrophenyl-beta-D-galactopyranoside (ONPG). Change in the activity of free and immobilized enzyme was determined at three different temperatures. Na-TPP crosslinked chitosan membranes were found to be permeable to solutes of up to 17,000Da molecular weight. The enzyme loading efficiency was higher in the barium alginate core (100%) as compared to the calcium alginate core (60%). The rate of ONPG conversion to o-nitrophenol was faster in the case of calcium alginate-chitosan microcapsules as compared to barium alginate-chitosan microcapsules. Barium alginate-chitosan microcapsules, however, did improve the stability of the enzyme at 37 degrees C relative to calcium alginate-chitosan microcapsules or free enzyme. This study illustrates a new method of enzyme immobilization for biotechnology applications using liquid or solid core and shell microcapsule technology.

  18. Making Polymeric Microspheres

    NASA Technical Reports Server (NTRS)

    Rhim, Won-Kyu; Hyson, Michael T.; Chung, Sang-Kun; Colvin, Michael S.; Chang, Manchium

    1989-01-01

    Combination of advanced techniques yields uniform particles for biomedical applications. Process combines ink-jet and irradiation/freeze-polymerization techniques to make polymeric microspheres of uniform size in diameters from 100 to 400 micrometer. Microspheres used in chromatography, cell sorting, cell labeling, and manufacture of pharmaceutical materials.

  19. Production of hollow aerogel microspheres

    SciTech Connect

    Upadhye, R.S.; Henning, S.A.

    1990-12-31

    A method is described for making hollow aerogel microspheres of 800--1200{mu} diameter and 100--300{mu} wall thickness by forming hollow alcogel microspheres during the sol/gel process in a catalytic atmosphere and capturing them on a foam surface containing catalyst. Supercritical drying of the formed hollow alcogel microspheres yields hollow aerogel microspheres which are suitable for ICF targets.

  20. Production of hollow aerogel microspheres

    DOEpatents

    Upadhye, Ravindra S.; Henning, Sten A.

    1993-01-01

    A method is described for making hollow aerogel microspheres of 800-1200 .mu. diameter and 100-300 .mu. wall thickness by forming hollow alcogel microspheres during the sol/gel process in a catalytic atmosphere and capturing them on a foam surface containing catalyst. Supercritical drying of the formed hollow alcogel microspheres yields hollow aerogel microspheres which are suitable for ICF targets.

  1. Metabolism of proteinoid microspheres

    NASA Technical Reports Server (NTRS)

    Nakashima, T.; Fox, S. W. (Principal Investigator)

    1987-01-01

    The literature of metabolism in proteinoids and proteinoid microspheres is reviewed and criticized from a biochemical and experimental point of view. Closely related literature is also reviewed in order to understand the function of proteinoids and proteinoid microspheres. Proteinoids or proteinoid microspheres have many activities. Esterolysis, decarboxylation, amination, deamination, and oxidoreduction are catabolic enzyme activities. The formation of ATP, peptides or oligonucleotides is synthetic enzyme activities. Additional activities are hormonal and inhibitory. Selective formation of peptides is an activity of nucleoproteinoid microspheres; these are a model for ribosomes. Mechanisms of peptide and oligonucleotide syntheses from amino acids and nucleotide triphosphate by proteinoid microspheres are tentatively proposed as an integrative consequence of reviewing the literature.

  2. Metabolism of proteinoid microspheres

    NASA Technical Reports Server (NTRS)

    Nakashima, T.; Fox, S. W. (Principal Investigator)

    1987-01-01

    The literature of metabolism in proteinoids and proteinoid microspheres is reviewed and criticized from a biochemical and experimental point of view. Closely related literature is also reviewed in order to understand the function of proteinoids and proteinoid microspheres. Proteinoids or proteinoid microspheres have many activities. Esterolyis, decarboxylation, amination, deamination, and oxidoreduction are catabolic enzyme activities. The formation of ATP, peptides or oligonucleotides is synthetic enzyme activities. Additional activities are hormonal and inhibitory. Selective formation of peptides is an activity of nucleoproteinoid microspheres; these are a model for ribosomes. Mechanisms of peptide and oligonucleotide syntheses from amino acids and nucleotide triphosphate by proteinoid microspheres are tentatively proposed as an integrative consequence of reviewing the literature.

  3. Preparation and swelling properties of pH-sensitive composite hydrogel beads based on chitosan-g-poly (acrylic acid)/vermiculite and sodium alginate for diclofenac controlled release.

    PubMed

    Wang, Qin; Xie, Xiaoling; Zhang, Xiaowei; Zhang, Junping; Wang, Aiqin

    2010-04-01

    A series of pH-sensitive composite hydrogel beads, chitosan-g-poly (acrylic acid)/vermiculite/sodium alginate (CTS-g-PAA/VMT/SA), was prepared using CTS-g-PAA/VMT composite and SA by Ca(2+) as the crosslinking agent. The structure and morphologies of the developed composite hydrogel beads were characterized by Fourier transform infrared spectroscopy and scanning electron microscopy. The swelling properties and pH-sensitivity of the beads were investigated. In addition, the drug loading and controlled release behaviors of the beads were also evaluated using diclofenac sodium (DS) as the model drug in stimulated gastric fluids (pH 2.1) and intestinal fluids (pH 6.8). The results indicate that the composite hydrogel beads showed good pH-sensitivity. The release rate of the drug from the composite hydrogel beads is remarkably slowed down, which indicated that incorporating VMT into the composite hydrogel beads can improve the burst release effect of the drug.

  4. Electrophoretic cell separation by means of microspheres

    NASA Technical Reports Server (NTRS)

    Smolka, A. J. K.; Nerren, B. H.; Margel, S.; Rembaum, A.

    1979-01-01

    The electrophoretic mobility of fixed human erythrocytes immunologically labeled with poly(vinylpyridine) or poly(glutaraldehyde) microspheres was reduced by approximately 40%. This observation was utilized in preparative scale electrophoretic separations of fixed human and turkey erythrocytes, the mobilities of which under normal physiological conditions do not differ sufficiently to allow their separation by continuous flow electrophoresis. We suggest that resolution in the electrophoretic separation of cell subpopulations, currently limited by finite and often overlapping mobility distributions, may be significantly enhanced by immunospecific labeling of target populations using microspheres.

  5. Encapsulation in alginate and alginate coated-chitosan improved the survival of newly probiotic in oxgall and gastric juice.

    PubMed

    Trabelsi, Imen; Bejar, Wacim; Ayadi, Dorra; Chouayekh, Hichem; Kammoun, Radhouane; Bejar, Samir; Ben Salah, Riadh

    2013-10-01

    This study was undertaken to develop an optimum composition model for the microencapsulation of a newly probiotic on sodium alginate using response surface methodology. The individual and interactive effects of three independent variables, namely sodium alginate concentration, biomass concentration, and hardening time, were investigated using Box-Behnken design experiments. A second ordered polynomial model was fitted and optimum conditions were estimated. The optimal conditions identified were 2% for sodium alginate, 10(10)UFC/ml for biomass, and 30 min for hardening time. The experimental value obtained for immobilized cells under these conditions was about 80.98%, which was in close agreement with the predicted value of 82.6%. Viability of microspheres (96%) was enhanced with chitosan as coating materials. The survival rates of free and microencapsulated Lactobacillus plantarum TN8 during exposure to artificial gastrointestinal conditions were compared. The results revealed that the encapsulated cells exhibited significantly higher resistances to artificial intestinal juice (AIJ) and artificial gastric juice (AGJ). Microencapsulation was also noted to effectively protect the strain from heating at 65 °C and refrigerating at 4 °C. Taken together, the findings indicated that microencapsulation conferred important protective effects to L. plantarum against the gastrointestinal conditions encountered during the transit of food.

  6. Improving photoprotection: 4-methylbenzylidene camphor microspheres.

    PubMed

    Centini, Marisanna; Miraglia, Giovanna; Quaranta, Valeria; Buonocore, Anna; Anselmi, Cecilia

    2014-05-22

    Abstract We propose a new approach for photoprotection. 4-Methylbenzylidene camphor (4-MBC), one of the most widely used UV filters, was encapsulated in microspheres, with a view to overcoming problems (percutaneous absorption, photodegradation and lack of lasting effect) arising with organic sunscreens, and to achieve safe photoprotection. We focused on this filter in the light of the Cosmetics Europe opinion concerning its possible effects on the thyroid gland. Microspheres were prepared by emulsification-solvent evaporation, using different amounts of 4-MBC and characterized for morphology, encapsulation efficiency and particle size. The particles were then mixed in O/W emulsions. The in vitro sun protection factors, in vitro release and photostability were investigated and compared with emulsions containing the free sunscreen. The new microspheres offer good morphology and loading (up to 40%), and the same photoprotection as the free filter while at the same time protecting it from photodegradation. The systems also give a slower release from the emulsions.

  7. 21 CFR 184.1610 - Potassium alginate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Potassium alginate. 184.1610 Section 184.1610 Food... Specific Substances Affirmed as GRAS § 184.1610 Potassium alginate. (a) Potassium alginate (CAS Reg. No. 9005-36-1) is the potassium salt of alginic acid, a natural polyuronide constituent of certain...

  8. 21 CFR 184.1610 - Potassium alginate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Potassium alginate. 184.1610 Section 184.1610 Food... Specific Substances Affirmed as GRAS § 184.1610 Potassium alginate. (a) Potassium alginate (CAS Reg. No. 9005-36-1) is the potassium salt of alginic acid, a natural polyuronide constituent of certain...

  9. 21 CFR 184.1610 - Potassium alginate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Potassium alginate. 184.1610 Section 184.1610 Food... Specific Substances Affirmed as GRAS § 184.1610 Potassium alginate. (a) Potassium alginate (CAS Reg. No. 9005-36-1) is the potassium salt of alginic acid, a natural polyuronide constituent of certain...

  10. 21 CFR 184.1610 - Potassium alginate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Potassium alginate. 184.1610 Section 184.1610 Food... Specific Substances Affirmed as GRAS § 184.1610 Potassium alginate. (a) Potassium alginate (CAS Reg. No. 9005-36-1) is the potassium salt of alginic acid, a natural polyuronide constituent of certain...

  11. 21 CFR 184.1724 - Sodium alginate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Sodium alginate. 184.1724 Section 184.1724 Food... Specific Substances Affirmed as GRAS § 184.1724 Sodium alginate. (a) Sodium alginate (CAS Reg. No. 9005-38-3) is the sodium salt of alginic acid, a natural polyuronide constituent of certain brown...

  12. 21 CFR 184.1724 - Sodium alginate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Sodium alginate. 184.1724 Section 184.1724 Food... Specific Substances Affirmed as GRAS § 184.1724 Sodium alginate. (a) Sodium alginate (CAS Reg. No. 9005-38-3) is the sodium salt of alginic acid, a natural polyuronide constituent of certain brown...

  13. 21 CFR 184.1724 - Sodium alginate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Sodium alginate. 184.1724 Section 184.1724 Food... Specific Substances Affirmed as GRAS § 184.1724 Sodium alginate. (a) Sodium alginate (CAS Reg. No. 9005-38-3) is the sodium salt of alginic acid, a natural polyuronide constituent of certain brown...

  14. Formulation and evaluation of reconstitutable suspensions containing ibuprofen-loaded Eudragit microspheres.

    PubMed

    Devrim, Burcu; Bozkir, Asuman; Canefe, Kandemir

    2011-01-01

    The objective of this work was to develop and evaluate reconstitutable suspensions of ibuprofen-loaded microspheres prepared with an acrylic polymer (Eudragit RS-PM). The microspheres were prepared by the quasi-emulsion solvent diffusion technique. To prepare reconstitutable suspension formulation, the microspheres used had a mean particle size of 316.6 microm and 99.8% loading efficiency. Xanthan gum was chosen as the suspending agent for the suspension formulations. D-sorbitol was used to impart palatability of suspensions. The amount of D-sorbitol affected sedimentation volume and redispersibility properties of suspensions. The highest improving effect was shown with 20.0% and 25.0% of D-sorbitol concentrations. It was observed that dispersion media of suspensions showed non-Newtonian flow characteristics. To ensure minimum drug leakage from the microspheres into the suspension, the pH was buffered at 3.60 using citrate buffer. The ibuprofen content calculated from the suspended microspheres was consistent with that from microspheres alone. This result indicated that no leakage of drug occurred from the microspheres in the suspension on storage. Moreover, the same release rate of ibuprofen from the microspheres suspension and microspheres alone indicated that the suspension medium studied did not affect the property of drug release. This study suggested that stable suspensions of ibuprofen-loaded microspheres could be formulated with 0.6% w/v xanthan gum by the addition of 20% w/v D-sorbitol.

  15. The angiogenic effect of ONO-1301, a novel long-acting prostacyclin agonist loaded in PLGA microspheres prepared using different molecular weights of PLGA, in a murine sponge model.

    PubMed

    Hazekawa, Mai; Morihata, Kana; Yoshida, Miyako; Sakai, Yoshiki; Uchida, Takahiro

    2014-11-01

    The purpose of this study was to evaluate the angiogenic effect of topical application of three types of ONO-1301-loaded poly (lactide-co-glycolide) microspheres (ONO-1301 PLGA MS). ONO-1301 PLGA MS were prepared with PLGA 5010, 5020 and 5050 (with molecular weights of 10 K, 20 K and 50 K, respectively), using the solvent evaporation method. The lactide:glycolide ratio was fixed at 50:50; only the molecular weight was varied. The microspheres had an average diameter of almost 25 µm, and a loading efficiency of at least 70%. The sustained-release effect and its dependence on the molecular weight of the polymer used was confirmed in an in vitro drug-release test and by measuring subcutaneous plasma levels after administration of the three types of ONO-1301 PLGA MS to rats for 28 days. In the murine sponge model, the three types of ONO-1301 PLGA MS were administered to mice in a subcutaneously placed sponge and hemoglobin and hepatocyte growth factor (HGF) levels in the sponge were measured at predefined intervals up to 28 days. The hemoglobin and HGF levels obtained were significantly higher than those obtained after daily administration of ONO-1301 powder. Additional in vivo fluorescence imaging showed that PLGA MS remained in the sponge for 28 days. In conclusion, the three types of ONO-1301 PLGA MS prepared with PLGA three different molecular weight suppress the burst release, stimulate angiogenesis on topical application in a murine sponge model. This formulation may therefore be capable of improving the clinical picture in some types of vascular disease.

  16. Biocompatible Double-Membrane Hydrogels from Cationic Cellulose Nanocrystals and Anionic Alginate as Complexing Drugs Codelivery.

    PubMed

    Lin, Ning; Gèze, Annabelle; Wouessidjewe, Denis; Huang, Jin; Dufresne, Alain

    2016-03-23

    A biocompatible hydrogel with a double-membrane structure is developed from cationic cellulose nanocrystals (CNC) and anionic alginate. The architecture of the double-membrane hydrogel involves an external membrane composed of neat alginate, and an internal composite hydrogel consolidates by electrostatic interactions between cationic CNC and anionic alginate. The thickness of the outer layer can be regulated by the adsorption duration of neat alginate, and the shape of the inner layer can directly determine the morphology and dimensions of the double-membrane hydrogel (microsphere, capsule, and filmlike shapes). Two drugs are introduced into the different membranes of the hydrogel, which will ensure the complexing drugs codelivery and the varied drugs release behaviors from two membranes (rapid drug release of the outer hydrogel, and prolonged drug release of the inner hydrogel). The double-membrane hydrogel containing the chemically modified cellulose nanocrystals (CCNC) in the inner membrane hydrogel can provide the sustained drug release ascribed to the "nano-obstruction effect" and "nanolocking effect" induced by the presence of CCNC components in the hydrogels. Derived from natural polysaccharides (cellulose and alginate), the novel double-membrane structure hydrogel material developed in this study is biocompatible and can realize the complexing drugs release with the first quick release of one drug and the successively slow release of another drug, which is expected to achieve the synergistic release effects or potentially provide the solution to drug resistance in biomedical application.

  17. Alginate gelation-induced cell death during laser-assisted cell printing.

    PubMed

    Gudapati, Hemanth; Yan, Jingyuan; Huang, Yong; Chrisey, Douglas B

    2014-09-01

    Modified laser-induced forward transfer has emerged as a promising bioprinting technique. Depending on the operating conditions and cell properties, laser cell printing may cause cell injury and even death, which should be carefully elucidated for it to be a viable technology. This study has investigated the effects of alginate gelation, gelation time, alginate concentration, and laser fluence on the post-transfer cell viability of NIH 3T3 fibroblasts. Sodium alginate and calcium chloride are used as the gel precursor and gel reactant solution to form cell-laden alginate microspheres. It is found that the effects of gelation depend on the duration of gelation. Two-minute gelation is observed to increase the cell viability after 24 h incubation, mainly due to the protective cushion effect of the forming gel membrane during droplet landing. Despite the cushion effect from 10 min gelation, it is observed that the cell viability decreases after 24 h incubation because of the forming thick gel membrane that reduces nutrient and oxygen diffusion from the culture medium. In addition, the cell viability after 24 h incubation decreases as the laser fluence or alginate concentration increases.

  18. Microsphere Insulation Panels

    NASA Technical Reports Server (NTRS)

    Mohling, R.; Allen, M.; Baumgartner, R.

    2006-01-01

    Microsphere insulation panels (MIPs) have been developed as lightweight, longlasting replacements for the foam and vacuum-jacketed systems heretofore used for thermally insulating cryogenic vessels and transfer ducts. The microsphere core material of a typical MIP consists of hollow glass bubbles, which have a combination of advantageous mechanical, chemical, and thermal-insulation properties heretofore available only separately in different materials. In particular, a core filling of glass microspheres has high crush strength and low density, is noncombustible, and performs well in soft vacuum.

  19. Development of a novel 3-month drug releasing risperidone microspheres

    PubMed Central

    Yerragunta, Bhanusree; Jogala, Satheesh; Chinnala, Krishna Mohan; Aukunuru, Jithan

    2015-01-01

    Objective: The purpose of this study was to develop an ideal microsphere formulation of risperidone that would prolong the drug release for 3 months in vivo and avoid the need for co-administration of oral tablets. Materials and Methods: Polycaprolactones (PCL) were used as polymers to prepare microspheres. The research included screening and optimizing of suitable commercial polymers of variable molecular weights: PCL-14000, PCL-45000, PCL-80000 or the blends of these polymers to prepare microspheres with zero-order drug-releasing properties without the lag phase. In the present study, the sustained release risperidone microspheres were prepared by o/w emulsion solvent evaporation technique and the yield was determined. Microspheres were evaluated for their drug content and in vitro drug release. Microspheres prepared using a blend of PCL-45000 and PCL-80000 at a ratio of 1:1 resulted in the release of the drug in a time frame of 90 days, demonstrated zero-order drug release without lag time and burst release. This formulation was considered optimized formulation. Optimized formulation was characterized for solid state of the drug using differential scanning calorimetry, surface morphology using scanning electron microscopy and in vivo drug release in rats. Results: The surface of the optimized formulation was smooth, and the drug changed its physical form in the presence of blends of polymers and upon fabrication of microspheres. The optimized formulation also released the drug in vivo for a period of 90 days. Conclusions: From our study, it was concluded that these optimized microspheres showed great potential for a better depot preparation than the marketed Risperdal Consta™ and, therefore, could further improve patient compliance. PMID:25709335

  20. Polymerization Induced Self-Assembly of Alginate Based Amphiphilic Graft Copolymers Synthesized by Single Electron Transfer Living Radical Polymerization.

    PubMed

    Kapishon, Vitaliy; Whitney, Ralph A; Champagne, Pascale; Cunningham, Michael F; Neufeld, Ronald J

    2015-07-13

    Alginate-based amphiphilic graft copolymers were synthesized by single electron transfer living radical polymerization (SET-LRP), forming stable micelles during polymerization induced self-assembly (PISA). First, alginate macroinitiator was prepared by partial depolymerization of native alginate, solubility modification and attachment of initiator. Depolymerized low molecular weight alginate (∼12 000 g/mol) was modified with tetrabutylammonium, enabling miscibility in anhydrous organic solvents, followed by initiator attachment via esterification yielding a macroinitiator with a degree of substitution of 0.02, or 1-2 initiator groups per alginate chain. Then, methyl methacrylate was polymerized from the alginate macroinitiator in mixtures of water and methanol, forming poly(methyl methacrylate) grafts, prior to self-assembly, of ∼75 000 g/mol and polydispersity of 1.2. PISA of the amphiphilic graft-copolymer resulted in the formation of micelles with diameters of 50-300 nm characterized by light scattering and electron microscopy. As the first reported case of LRP from alginate, this work introduces a synthetic route to a preparation of alginate-based hybrid polymers with a precise macromolecular architecture and desired functionalities. The intended application is the preparation of micelles for drug delivery; however, LRP from alginate can also be applied in the field of biomaterials to the improvement of alginate-based hydrogel systems such as nano- and microhydrogel particles, islet encapsulation materials, hydrogel implants, and topical applications. Such modified alginates can also improve the function and application of native alginates in food and agricultural applications.

  1. Superabsorbent nanocomposite (alginate-g-PAMPS/MMT): synthesis, characterization and swelling behavior.

    PubMed

    Yadav, Mithilesh; Rhee, Kyong Yop

    2012-09-01

    A superabsorbent composite (alginate-g-PAMPS/MMT) was prepared by graft copolymerization from alginate, 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS) and Na+ montmorillonite (MMT) in an inert atmosphere. Effects of polymerization variables on water absorbency, including the content of Na+ montmorillonite, sodium alginate, N,N'-methylenebisacrylamide and AMPS, were studied. The introduced montmorillonite formed a loose and porous surface and improved the water absorbency of the alginate-g-PAMPS/MMT superabsorbent composite. Swelling behaviors of the superabsorbent composites in various cationic salt solutions (NaCl, CaCl2 and FeCl3) and anionic salt solutions (NaCl and Na2SO4) were also systematically investigated. The superabsorbent composite was further characterized using Fourier transform infrared spectroscopy (FTIR), rheology, thermogravimetric analysis (TGA), X-ray diffraction (XRD) and scanning electron microscopy (SEM) taking alginate-g-PAMPS as a reference.

  2. Development and physicochemical characterization of alginate composite film loaded with simvastatin as a potential wound dressing.

    PubMed

    Rezvanian, Masoud; Amin, Mohd Cairul Iqbal Mohd; Ng, Shiow-Fern

    2016-02-10

    Previously, studies have demonstrated that topical application of simvastatin can promote wound healing in diabetic mice via augmentation of angiogenesis and lymphangiogenesis. This study aimed to formulate and characterize simvastatin in alginate-based composite film wound dressings. Biopolymers used for composite films were sodium alginate blended with pectin or gelatin. The films were prepared and characterized based on their physical properties, surface morphology, mechanical strength and rheology. Then, in vitro drug releases from the films were investigated and, finally, the cell viability assay was performed to assess the cytotoxicity profile. From the pre-formulation studies, alginate/pectin composite film showed to possess desirable wound dressing properties and superior mechanical properties. The in vitro drug release profile revealed that alginate/pectin film produced a controlled release drug profile, and cell viability assay showed that the film was non-toxic. In summary, alginate/pectin composite film is suitable to be formulated with simvastatin as a potential wound dressing.

  3. Innovative plasticized alginate obtained by thermo-mechanical mixing: Effect of different biobased polyols systems.

    PubMed

    Gao, Chengcheng; Pollet, Eric; Avérous, Luc

    2017-02-10

    Plasticized alginate films with different biobased polyols (glycerol and sorbitol) and their mixtures were successfully prepared by thermo-mechanical mixing instead of the usual casting-evaporation procedure. The microstructure and properties of the different plasticized alginate formulations were investigated by SEM, FTIR, XRD, DMTA and uniaxial tensile tests. SEM and XRD results showed that native alginate particles were largely destructured with the plasticizers (polyols and water), under a thermo-mechanical input. With increasing amount of plasticizers, the samples showed enhanced homogeneity while their thermal and mechanical properties decreased. Compared to sorbitol, glycerol resulted in alginate films with a higher flexibility due to its better plasticization efficiency resulting from its smaller size and higher hydrophilic character. Glycerol and sorbitol mixtures seemed to be an optimum to obtain the best properties. This work showed that thermo-mechanical mixing is a promising method to produce, at large scale, plasticized alginate-based films with improved properties.

  4. Amorphous and nanostructured silica and aluminosilicate spray-dried microspheres

    NASA Astrophysics Data System (ADS)

    Todea, M.; Turcu, R. V. F.; Frentiu, B.; Tamasan, M.; Mocuta, H.; Ponta, O.; Simon, S.

    2011-08-01

    Amorphous silica and aluminosilicate microspheres with diameters in the 0.1-20 μm range were produced by spray drying method. SEM, TEM and AFM images showed the spherical shape of the obtained particles. Based on thermal analysis data, several heat treatments have been applied on the as-prepared samples in order to check the amorphous state stability of the microspheres and to develop nanosized crystalline phases. As-prepared microspheres remain amorphous up to 1400 °C. By calcination at 1400 °C, cristobalite type nanocrystals are developed on silica sample, while in aluminosilicate sample first are developed mullite type nanocrystals and only after prolonged treatment are developed also cristobalite type nanocrystals. 29Si and 27Al MAS NMR results show that the local order around aluminum and silicon atoms strongly depend on the thermal history of the microspheres.

  5. POROUS WALL, HOLLOW GLASS MICROSPHERES

    SciTech Connect

    Sexton, W.

    2012-06-30

    Hollow Glass Microspheres (HGM) is not a new technology. All one has to do is go to the internet and Google{trademark} HGM. Anyone can buy HGM and they have a wide variety of uses. HGM are usually between 1 to 100 microns in diameter, although their size can range from 100 nanometers to 5 millimeters in diameter. HGM are used as lightweight filler in composite materials such as syntactic foam and lightweight concrete. In 1968 a patent was issued to W. Beck of the 3M{trademark} Company for 'Glass Bubbles Prepared by Reheating Solid Glass Particles'. In 1983 P. Howell was issued a patent for 'Glass Bubbles of Increased Collapse Strength' and in 1988 H. Marshall was issued a patent for 'Glass Microbubbles'. Now Google{trademark}, Porous Wall, Hollow Glass Microspheres (PW-HGMs), the key words here are Porous Wall. Almost every article has its beginning with the research done at the Savannah River National Laboratory (SRNL). The Savannah River Site (SRS) where SRNL is located has a long and successful history of working with hydrogen and its isotopes for national security, energy, waste management and environmental remediation applications. This includes more than 30 years of experience developing, processing, and implementing special ceramics, including glasses for a variety of Department of Energy (DOE) missions. In the case of glasses, SRS and SRNL have been involved in both the science and engineering of vitreous or glass based systems. As a part of this glass experience and expertise, SRNL has developed a number of niches in the glass arena, one of which is the development of porous glass systems for a variety of applications. These porous glass systems include sol gel glasses, which include both xerogels and aerogels, as well as phase separated glass compositions, that can be subsequently treated to produce another unique type of porosity within the glass forms. The porous glasses can increase the surface area compared to 'normal glasses of a 1 to 2 order of

  6. Alginate Nanoparticles as a Promising Adjuvant and Vaccine Delivery System

    PubMed Central

    Sarei, F.; Dounighi, N. Mohammadpour; Zolfagharian, H.; Khaki, P.; Bidhendi, S. Moradi

    2013-01-01

    During last decades, diphtheria has remained as a serious disease that still outbreaks and can occur worldwide. Recently, new vaccine delivery systems have been developed by using the biodegradable and biocompatible polymers such as alginate. Alginate nanoparticles as a carrier with adjuvant and prolong release properties that enhance the immunogenicity of vaccines. In this study diphtheria toxoid loaded nanoparticles were prepared by ionic gelation technique and characterized with respect to size, zeta potential, morphology, encapsulation efficiency, release profile, and immunogenicity. Appropriate parameters (calcium chloride and sodium alginate concentration, homogenization rate and homogenization time) redounded to the formation of suitable nanoparticles with a mean diameter of 70±0.5 nm. The loading studies of the nanoparticles resulted in high loading capacities (>90%) and subsequent release studies showed prolong profile. The stability and antigenicity of toxoid were evaluated by sodium dodecyl sulfate polyacrylamide gel electrophoresis and ouchterlony test and proved that the encapsulation process did not affect the antigenic integrity and activity. Guinea pigs immunized with the diphtheria toxoid-loaded alginate nanoparticles showed highest humoral immune response than conventional vaccine. It is concluded that, with regard to the desirable properties of nanoparticles and high immunogenicity, alginate nanoparticles could be considered as a new promising vaccine delivery and adjuvant system. PMID:24302799

  7. Organic aerogel microspheres

    DOEpatents

    Mayer, Steven T.; Kong, Fung-Ming; Pekala, Richard W.; Kaschmitter, James L.

    1999-01-01

    Organic aerogel microspheres which can be used in capacitors, batteries, thermal insulation, adsorption/filtration media, and chromatographic packings, having diameters ranging from about 1 micron to about 3 mm. The microspheres can be pyrolyzed to form carbon aerogel microspheres. This method involves stirring the aqueous organic phase in mineral oil at elevated temperature until the dispersed organic phase polymerizes and forms nonsticky gel spheres. The size of the microspheres depends on the collision rate of the liquid droplets and the reaction rate of the monomers from which the aqueous solution is formed. The collision rate is governed by the volume ratio of the aqueous solution to the mineral oil and the shear rate, while the reaction rate is governed by the chemical formulation and the curing temperature.

  8. Organic aerogel microspheres

    DOEpatents

    Mayer, S.T.; Kong, F.M.; Pekala, R.W.; Kaschmitter, J.L.

    1999-06-01

    Organic aerogel microspheres are disclosed which can be used in capacitors, batteries, thermal insulation, adsorption/filtration media, and chromatographic packings, having diameters ranging from about 1 micron to about 3 mm. The microspheres can be pyrolyzed to form carbon aerogel microspheres. This method involves stirring the aqueous organic phase in mineral oil at elevated temperature until the dispersed organic phase polymerizes and forms nonstick gel spheres. The size of the microspheres depends on the collision rate of the liquid droplets and the reaction rate of the monomers from which the aqueous solution is formed. The collision rate is governed by the volume ratio of the aqueous solution to the mineral oil and the shear rate, while the reaction rate is governed by the chemical formulation and the curing temperature.

  9. Methylene blue adsorption on graphene oxide/calcium alginate composites.

    PubMed

    Li, Yanhui; Du, Qiuju; Liu, Tonghao; Sun, Jiankun; Wang, Yonghao; Wu, Shaoling; Wang, Zonghua; Xia, Yanzhi; Xia, Linhua

    2013-06-05

    Graphene oxide has been used as an adsorbent in wastewater treatment. However, the dispersibility in aqueous solution and the biotoxicity to human cells of graphene oxide limits its practical application in environmental protection. In this research, a novel environmental friendly adsorbent, calcium alginate immobilized graphene oxide composites was prepared. The effects of pH, contact time, temperature and dosage on the adsorption properties of methylene blue onto calcium alginate immobilized graphene oxide composites were investigated. The equilibrium adsorption data were described by the Langmuir and Freundlich isotherms. The maximum adsorption capacity obtained from Langmuir isotherm equation was 181.81 mg/g. The pseudo-first order, pseudo-second order, and intraparticle diffusion equation were used to evaluate the kinetic data. Thermodynamic analysis of equilibriums indicated that the adsorption reaction of methylene blue onto calcium alginate immobilized graphene oxide composites was exothermic and spontaneous in nature.

  10. Alginate: properties and biomedical applications

    PubMed Central

    Lee, Kuen Yong; Mooney, David J.

    2011-01-01

    Alginate is a biomaterial that has found numerous applications in biomedical science and engineering due to its favorable properties, including biocompatibility and ease of gelation. Alginate hydrogels have been particularly attractive in wound healing, drug delivery, and tissue engineering applications to date, as these gels retain structural similarity to the extracellular matrices in tissues and can be manipulated to play several critical roles. This review will provide a comprehensive overview of general properties of alginate and its hydrogels, their biomedical applications, and suggest new perspectives for future studies with these polymers. PMID:22125349

  11. Surfactant and metal ion effects on the mechanical properties of alginate hydrogels.

    PubMed

    Kaygusuz, Hakan; Evingür, Gülşen Akın; Pekcan, Önder; von Klitzing, Regine; Erim, F Bedia

    2016-11-01

    This paper addresses the controlled variation of the mechanical properties of alginate gel beads by changing the alginate concentration or by adding different surfactants or cross-linking cations. Alginate beads containing nonionic Brij 35 or anionic sodium dodecyl sulfate (SDS) surfactants were prepared with two different types of cations (Ca(2+), Ba(2+)) as crosslinkers. Compression measurements were performed to investigate the effect of the surfactant and cation types and their concentrations on the Young's modulus of alginate beads. The Young's modulus was determined by using Hertz theory. For all types of alginate gel beads the Young's modulus showed an increasing value for increasing alginate contents. Addition of the anionic surfactant SDS increases the Young's modulus of the alginate beads while the addition of non-ionic surfactant Brij 35 leads to a decrease in Young's modulus. This opposite behavior is related to the contrary effect of both surfactants on the charge of the alginate beads. When Ba(2+) ions were used as crosslinker cation, the Young's modulus of the beads with the surfactant SDS was found to be approximately two times higher than the modulus of beads with the surfactant Brij 35. An ion specific effect was found for the crosslinking ability of divalent cations.

  12. Compartmentalization in proteinoid microspheres

    NASA Technical Reports Server (NTRS)

    Brooke, S.; Fox, S. W.

    1977-01-01

    Proteinoid microspheres with stable internal compartments and internal structure are made from acidic proteinoid and basic proteinoid with calcium. The populations of microspheres are characterized by a wide diversity of structure. A model of primitive intracellular communication is suggested by the observed movement of internal particles between compartments of a multicompartmentalized unit. Differential response to pH change and to temperature change has been demonstrated within one population and suggests one mode of adaptive selection among primordial cell populations.

  13. Synthesis and catalytic performance of SiO2@Ni and hollow Ni microspheres

    NASA Astrophysics Data System (ADS)

    Liu, Xin; Liu, Yanhua; Shi, Xueting; Yu, Zhengyang; Feng, Libang

    2016-11-01

    Nickel (Ni) catalyst has been widely used in catalytic reducing reactions such as catalytic hydrogenation of organic compounds and catalytic reduction of organic dyes. However, the catalytic efficiency of pure Ni is low. In order to improve the catalytic performance, Ni nanoparticle-loaded microspheres can be developed. In this study, we have prepared Ni nanoparticle-loaded microspheres (SiO2@Ni) and hollow Ni microspheres using two-step method. SiO2@Ni microspheres with raspberry-like morphology and core-shell structure are synthesized successfully using SiO2 microsphere as a template and Ni2+ ions are adsorbed onto SiO2 surfaces via electrostatic interaction and then reduced and deposited on surfaces of SiO2 microspheres. Next, the SiO2 cores are removed by NaOH etching and the hollow Ni microspheres are prepared. The NaOH etching time does no have much influence on the crystal structure, shape, and surface morphology of SiO2@Ni; however, it can change the phase composition evidently. The hollow Ni microspheres are obtained when the NaOH etching time reaches 10 h and above. The as-synthesized SiO2@Ni microspheres exhibit much higher catalytic performance than the hollow Ni microspheres and pure Ni nanoparticles in the catalytic reduction of methylene blue. Meanwhile, the SiO2@Ni catalyst has high stability and hence it can be recycled for reuse.

  14. Synthesis and Characterization of Sodium Alginate Conjugate and Study of Effect of Conjugation on Drug Release from Matrix Tablet

    PubMed Central

    Satheeshababu, B. K.; Mohamed, I.

    2015-01-01

    The aim of the present research work to study the effect of conjugation of the polymer on drug release from the matrix tablets. Sodium alginate L-cysteine conjugate was achieved by covalent attachment of thiol group of L-cysteine with the primary amino group of sodium alginate through the amide bonds formed by primary amino groups of the sodium alginate and the carboxylic acid group of L-cysteine. The synthesised sodium alginate L-cysteine conjugate was characterised by determining of charring point, Fourier transmission-infrared and differential scanning calorimetric analysis. To study the effect of conjugation on drug release pattern, the matrix tablets were prepared using various proportions of sodium alginate and sodium alginate L-cysteine conjugate along with atorvastatin calcium as model drug. The wet granulation technique was adopted and prepared matrix tablets were evaluated for various physical parameters. The in vitro drug release study results suggested that tablet formulated in combination of sodium alginate and sodium alginate L-cysteine conjugate S4 showed 100% after 8 h drug release whereas formulated with only sodium alginate S0 released 40% in 8 h. PMID:26798173

  15. Hydrothermal synthesis and photocatalytic performance of hierarchical Bi{sub 2}MoO{sub 6} microspheres using BiOI microspheres as self-sacrificing templates

    SciTech Connect

    Xu, Ming; Zhang, Wei-De

    2015-07-15

    Bi{sub 2}MoO{sub 6} hierarchical microspheres were successfully prepared through phase transformation from BiOI microspheres with the assistance of sodium citrate under hydrothermal condition. The possible formation mechanism for the conversion of BiOI to Bi{sub 2}MoO{sub 6} is discussed here. After being annealed at 300 °C for 2 h, the obtained Bi{sub 2}MoO{sub 6} microspheres exhibited remarkably enhanced photocatalytic activity towards the degradation of rhodamine B and phenol. The superior catalytic performance can be attributed to its larger surface area and higher crystallinity. In addition, Bi{sub 2}MoO{sub 6} microspheres are stable during the degradation reaction and can be used repeatedly. - Graphical abstract: Bi{sub 2}MoO{sub 6} hierarchical microspheres were successfully prepared through a facile partial anion exchange strategy using BiOI microspheres as self-sacrificing templates. The Bi{sub 2}MoO{sub 6} microspheres show high visible light photocatalytic activity. - Highlights: • Bi{sub 2}MoO{sub 6} microspheres were prepared via self-sacrificing template anion exchange. • Sodium citrate-assisted anion exchange for preparation of Bi{sub 2}MoO{sub 6} photocatalyst. • Bi{sub 2}MoO{sub 6} catalysts show high visible light photocatalytic activity.

  16. Facile synthesis of monodisperse porous Co3O4 microspheres with superior ethanol sensing properties.

    PubMed

    Sun, Chunwen; Rajasekhara, Shreyas; Chen, Yujin; Goodenough, John B

    2011-12-28

    A solvothermal method was developed to prepare on a large scale monodisperse porous β-Co(OH)(2) microspheres consisting of nanoplatelets. Co(3)O(4) microspheres with porous platelets were obtained via subsequent thermal decomposition. These Co(3)O(4) microspheres show much higher ethanol sensitivity and selectivity at a relatively low temperature (135 °C) compared with those of commercial Co(3)O(4) nanoparticles.

  17. Fabrication of uranium dioxide ceramic pellets with controlled porosity from oxide microspheres

    NASA Astrophysics Data System (ADS)

    Remy, E.; Picart, S.; Delahaye, T.; Jobelin, I.; Dugne, O.; Bisel, I.; Blanchart, P.; Ayral, A.

    2014-05-01

    This study concerns the fabrication of uranium oxide pellets using the powder-free process called Calcined Resin Microsphere Pelletization (CRMP). Details are given about oxide microsphere synthesis and particularly about loading operation and heat treatments. The fabrication of ceramic pellets is also described and discussed. Results showed that this process allows the preparation of either dense or porous pellets by mixing U3O8 and UO2-like microspheres before pressing and sintering.

  18. Influence of oligoguluronates on alginate gelation, kinetics, and polymer organization.

    PubMed

    Jørgensen, Tor Erik; Sletmoen, Marit; Draget, Kurt I; Stokke, Bjørn T

    2007-08-01

    Structural polysaccharides of the alginate family form gels in aqueous Ca2+-containing solutions by lateral association of chain segments. The effect of adding oligomers of alpha-l-guluronic acid (G blocks) to gelling solutions of alginate was investigated using rheology and atomic force microscopy (AFM). Ca-alginate gels were prepared by in situ release of Ca2+. The gel strength increased with increasing level of calcium saturation of the alginate and decreased with increasing amount of free G blocks. The presence of free G blocks also led to an increased gelation time. The gel point and fractal dimensionalities of the gels were determined based on the rheological characterization. Without added free G blocks the fractal dimension of the gels increased from df = 2.14 to df = 2.46 when increasing [Ca2+] from 10 to 20 mM. This increase was suggested to arise from an increased junction zone multiplicity induced by the increased concentration of calcium ions. In the presence of free G blocks (G block/alginate = 1/1) the fractal dimension increased from 2.14 to 2.29 at 10 mM Ca2+, whereas there was no significant change associated with addition of G blocks at 20 mM Ca2+. These observations indicate that free G blocks are involved in calcium-mediated bonds formed between guluronic acid sequences within the polymeric alginates. Thus, the added oligoguluronate competes with the alginate chains for the calcium ions. The gels and pregel situations close to the gel point were also studied using AFM. The AFM topographs indicated that in situations of low calcium saturation microgels a few hundred nanometers in diameter develop in solution. In situations of higher calcium saturation lateral association of a number of alginate chains are occurring, giving ordered fiber-like structures. These results show that G blocks can be used as modulators of gelation kinetics as well as local network structure formation and equilibrium properties in alginate gels.

  19. Method for sizing hollow microspheres

    DOEpatents

    Farnum, E.H.; Fries, R.J.

    1975-10-29

    Hollow Microspheres may be effectively sized by placing them beneath a screen stack completely immersed in an ultrasonic bath containing a liquid having a density at which the microspheres float and ultrasonically agitating the bath.

  20. Entrapment of cross-linked cellulase colloids in alginate beads for hydrolysis of cellulose.

    PubMed

    Nguyen, Le Truc; Lau, Yun Song; Yang, Kun-Lin

    2016-09-01

    Entrapment of enzymes in calcium alginate beads is a popular enzyme immobilization method. However, leaching of immobilized enzymes from the alginate beads is a common problem because enzyme molecules are much smaller than the pore size of alginate beads (∼200nm). To address this issue, we employ a millifluidic reactor to prepare cross-linked cellulase aggregate (XCA) colloids with a uniform size (∼300nm). Subsequently, these colloids are immobilized in calcium alginate beads as biocatalysts to hydrolyze cellulose substrates. By using fluorescent microscopy, we conclude that the immobilized XCA colloids distribute uniformly inside the beads and do not leach out from the beads after long-term incubation. Meanwhile, the pore size of the alginate beads is big enough for the cellulose substrates and fibers to diffuse into the beads for hydrolysis. For example, palm oil fiber and microcrystalline cellulose can be hydrolyzed within 48h and release reducing sugar concentrations up to 2.48±0.08g/l and 4.99±0.09g/l, respectively. Moreover, after 10 cycles of hydrolysis, 96.4% of the XCA colloids remain inside the alginate beads and retain 67% of the original activity. In contrast, free cellulase immobilized in the alginate beads loses its activity completely after 10 cycles. The strategy can also be used to prepare other types of cross-linked enzyme aggregates with high uniformity.

  1. Polycation-coated polyanion microspheres of urease for urea hydrolysis.

    PubMed

    Elçin, A E; Elçin, Y M

    2000-01-01

    Urease (EC 3.5.1.5) was immobilized within polyanionic carboxymethylcellulose/alginate (CMC/Alg) microspheres coated with a cationic polysaccharide, chitosan (C). Coating with chitosan improved the mechanically durability of the polyanionic microspheres, as well as increased enzyme immobilization yield [approximately 0.4 mg.mL-1 gel]. The effects of chitosan coating and CMC/Alg ratio on the water uptake and spherical morphology of the microspheres were investigated. The optimal pH of urease was not extensively affected by the immobilization procedure. However, the optimal temperature of urease activity increased upto 60 and 65 degrees C within CMC/Alg and C(CMC/Alg) microspheres, respectively, while the optimum for the free enzyme was 50 degrees C. The half life (t1/2) and deactivation rate constant (kd) of free urease were 79 min and 8.77 x 10(-3) min-1, respectively, whilst the t1/2 and kd values of urease within polyanion and polycation-coated polyanion microspheres were 142 min and 4.88 x 10(-3).min-1, and 179 min and 3.87 x 10(-3).min-1, at 80 degrees C, respectively. While the activation energy of the hydrolysis reaction of free urease was found to be 11.86 kJ.M-1.dm-3, it increased to 18.91 and 20.02 kJ.M-1.dm-3, for the immobilized urease within CMC/Alg and C(CMC/Alg) microspheres, respectively. The free enzyme exhibited K(m) and Vmax values of 2.85 mM.dm-3 and 31.9 mM.dm-3.s-1.g-1p-1, respectively, whilst the K(m) and Vmax for urease within polyanion and polycation-coated polyanion microspheres were 3.94 mM.dm-3 and 73.4 mM.dm-3.s-1.g-1.p-1, and 4.22 mM.dm-3 and 81.4 mM.dm-3.s-1.g-1.p-1, in the same order. C(CMC/Alg) microspheres showed a nearly stable urease activity of around 80-85% of the initial maximum activity, after the first 100 minutes.

  2. Effect of Various Polymers Concentrations on Physicochemical Properties of Floating Microspheres

    PubMed Central

    Jagtap, Y. M.; Bhujbal, R. K.; Ranade, A. N.; Ranpise, N. S.

    2012-01-01

    Floating microspheres have emerged as a potential candidate for gastroretentive drug delivery system. For developing a desired intragastric floatation system employing these microspheres, it is necessary to select an appropriate balance between buoyancy and drug releasing rate. These properties mainly depend on the polymers used in the formulation of the microspheres. Hence it is necessory to study the effect of these polymer concentrations on the various physicochemical properties of the microspheres. Floating microspheres were prepared by emulsion solvent evaporation technique utilising different polymers such as ethyl cellulose, Eudragit® RS and Eudragit® RL by dissolving them in a mixture of dichloromethane and methanol. Release modifiers studied were hydroxypropyl methylcellulose K4M, hydroxypropyl methylcellulose E50 LV and Eudragit® EPO. Prepared microspheres were analysed for particle size, surface morphology, entrapment efficiency, buoyancy, differential scanning calorimetry and in-vitro drug release. Ethyl cellulose and Eudragit® EPO resulted microspheres with high percentage yield, excellent spherical shape but had very less buoyancies with a high cumulative drug release. Ethyl cellulose microspheres prepared using hydroxypropyl methylcellulose K4M showed more sustained drug release and high buoyancies than that of the microspheres formulated with the hydroxypropyl methylcellulose E50 LV. Amongst these hydroxypropyl methylcellulose E50 LV showed good balance between buoyancy and the drug release. PMID:23798776

  3. A microfluidic approach to fabricate monodisperse hollow or porous poly(HEMA-MMA) microspheres using single emulsions as templates.

    PubMed

    Zhang, Hao; Ju, Xiao-Jie; Xie, Rui; Cheng, Chang-Jing; Ren, Ping-Wei; Chu, Liang-Yin

    2009-08-01

    We have successfully developed a novel and simple method to controllably prepare monodisperse poly(hydroxyethyl methacrylate-methyl methacrylate) (poly(HEMA-MMA)) microspheres with two distinct structures using single emulsions as templates. By employing a microfluidic emulsification approach to fabricate monomer-contained oil-in-water (O/W) emulsions as templates, and introducing proper initiators and different types of porogens, poly(HEMA-MMA) microspheres with hollow or porous structure are prepared in a controllable way. The shell thickness of hollow microspheres or the porosity of porous microspheres is controllably achieved by simply adjusting the porogen concentration. The prepared poly(HEMA-MMA) microspheres with controllable hollow or porous structures are favored for various potential applications. Furthermore, by using the simple preparation methodology proposed in this study, fabrication of monodisperse porous microspheres or hollow microcapsules with other materials can also be easily achieved.

  4. Oxygen sensing glucose biosensors based on alginate nano-micro systems

    NASA Astrophysics Data System (ADS)

    Chaudhari, Rashmi; Joshi, Abhijeet; Srivastava, Rohit

    2014-04-01

    Clinically glucose monitoring in diabetes management is done by point-measurement. However, an accurate, continuous glucose monitoring, and minimally invasive method is desirable. The research aims at developing fluorescence-mediated glucose detecting biosensors based on near-infrared radiation (NIR) oxygen sensitive dyes. Biosensors based on Glucose oxidase (GOx)-Rudpp loaded alginate microspheres (GRAM) and GOx-Platinum-octaethylporphyrin (PtOEP)-PLAalginate microsphere system (GPAM) were developed using air-driven atomization and characterized using optical microscopy, CLSM, fluorescence spectro-photometry etc. Biosensing studies were performed by exposing standard solutions of glucose. Uniform sized GRAM and GPAM with size 50+/-10μm were formed using atomization. CLSM imaging of biosensors suggests that Rudpp and PtOEP nanoparticles are uniformly distributed in alginate microspheres. The GRAM and GPAM showed a good regression constant of 0.974 and of 0.9648 over a range of 0-10 mM of glucose with a high sensitivity of 3.349%/mM (625 nm) and 2.38%/mM (645 nm) at 10 mM of glucose for GRAM and GPAM biosensor. GRAM and GPAM biosensors show great potential in development of an accurate and minimally invasive glucose biosensor. NIR dye based assays can aid sensitive, minimally-invasive and interference-free detection of glucose in diabetic patients.

  5. Design of controlled-release solid dosage forms of alginate and chitosan using microwave.

    PubMed

    Wong, Tin Wui; Chan, Lai Wah; Kho, Shyan Bin; Sia Heng, Paul Wan

    2002-12-05

    The influence of microwave irradiation on the drug release properties of alginate, alginate-chitosan and chitosan beads was investigated. The beads were prepared with the highest possible concentration of polymer by an extrusion method. Sulphathiazole was selected as a model drug. The beads were subjected to microwave irradiation at various combinations of irradiation power and time. The profiles of drug dissolution, drug content, drug stability, drug polymorphism, drug-polymer interaction, polymer crosslinkage and complexation were determined by dissolution testing, drug content assay, differential scanning calorimetry (DSC) and fourier transform infra-red spectroscopy (FTIR). The chemical stability of the drug entrapped in the beads was unaffected by the microwave irradiation. However, the drug in the chitosan beads underwent polymorphic changes. Polymorphic changes were prevented by means of drug-alginate interaction in alginate and alginate-chitosan beads. Changes in the polymorphic state of drug were found to have insignificant effect on the drug release profiles of chitosan beads. The release-retarding property of alginate and alginate-chitosan beads was significantly enhanced by subjecting the beads to microwave irradiation. Positively charged calcium ions and chitosan are known to interact with negatively charged alginate. DSC and FTIR analyses indicated that the reduction in rate and extent of drug released from the treated beads was primarily due to additional formation of non-ionic bonds, involving alginate crosslinkage and alginate-chitosan complexation. The results showed that microwave technology can be employed in the design of solid dosage forms for controlled-release application without the use of noxious chemical agents.

  6. Formulation and Coating of Alginate and Alginate-Hydroxypropylcellulose Pellets Containing Ranolazine.

    PubMed

    Segale, Lorena; Mannina, Paolo; Giovannelli, Lorella; Muschert, Susanne; Pattarino, Franco

    2016-11-01

    The formulation and the coating composition of biopolymeric pellets containing ranolazine were studied to improve their technological and biopharmaceutical properties. Eudragit L100 (EU L100) and Eudragit L30 D-55-coated alginate and alginate-hydroxypropylcellulose (HPC) pellets were prepared by ionotropic gelation using 3 concentrations of HPC (0.50%, 0.65%, and 1.00% wt/wt) and applying different percentages (5%, 10%, 20%, and 30% wt/wt) of coating material. The uncoated pellets were regular in shape and had mean diameter between 1490 and 1570 μm. The rate and the entity of the swelling process were affected by the polymeric composition: increasing the HPC concentration, the structure of the pellets became more compact and slowed down the penetration of fluids. Coated alginate-HPC formulations were able to control the drug release at neutral pH: a higher quantity of HPC in the system determined a slower release of the drug. The nature of the coating polymer and the coating level applied affected the drug release in acidic environment: EU L100 gave better performance than Eudragit L30 D-55 and the best coating level was 20%. The pellets containing 0.65% of HPC and coated with 20% EU L100 represented the best formulation, able to limit the drug release in acidic environment and to control it at pH 6.8.

  7. Fabrication of monodispersive nanoscale alginate-chitosan core-shell particulate systems for controlled release studies

    NASA Astrophysics Data System (ADS)

    Körpe, Didem Aksoy; Malekghasemi, Soheil; Aydın, Uğur; Duman, Memed

    2014-12-01

    Biopolymers such as chitosan and alginate are widely used for controlled drug delivery systems. The present work aimed to develop a new protocol for preparation of monodisperse alginate-coated chitosan nanoparticles at nanoscale. Modifications of preparation protocol contain changing the pH of polymer solutions and adding extra centrifugation steps into the procedure. While chitosan nanoparticles were synthesized by ionic gelation method, they were coated with alginate by electrostatic interaction. The size, morphology, charge, and structural characterization of prepared core-shell nanoparticulated system were performed by AFM, Zeta sizer, and FTIR. BSA and DOX were loaded as test biomolecules to core and shell part of the nanoparticle, respectively. Release profiles of BSA and DOX were determined by spectrophotometry. The sizes of both chitosan and alginate-coated chitosan nanoparticles which were prepared by modified protocol were measured to be 50 ± 10 and 60 ± 3 nm, respectively. After loading BSA and DOX, the average size of the particles increased to 80 ± 7 nm. Moreover, while the zeta potential of chitosan nanoparticles was positive value, the value was inverted to negative after alginate coating. Release profile measurements of BSA and DOX were determined during 57 and 2 days, respectively. Our results demonstrated that monodisperse alginate-coated nanoparticles were synthesized and loaded successfully using our modified protocol.

  8. Alginate electrodeposition onto three-dimensional porous Co-Ni films as drug delivery platforms.

    PubMed

    García-Torres, J; Gispert, C; Gómez, E; Vallés, E

    2015-01-21

    Three-dimensional porous Co-Ni films/alginate hybrid materials have been successfully prepared by electrodeposition to be used as a steerable magnetic device for drug delivery. Firstly, 3D porous Co-Ni films were prepared as substrates for the subsequent electrodeposition of the alginate biopolymer. Cyclic voltammetry, galvanostatic and potentiostatic studies were performed to establish the best conditions to obtain porous Co-Ni films. The electrochemical experiments were carried out in an electrolyte containing the metal salts and ammonium chloride at low pHs. In a second stage, the electrochemical deposition of alginate as a biocompatible polymer drug delivery carrier was performed. The characteristics of the alginate matrix were investigated in terms of electrochemical properties, morphology and drug release. The hybrid material obtained showed soft-magnetic behavior and drug release indicating its suitability to be used as a steerable magnetic drug delivery device.

  9. Injectable hydrogels derived from phosphorylated alginic acid calcium complexes.

    PubMed

    Kim, Han-Sem; Song, Minsoo; Lee, Eun-Jung; Shin, Ueon Sang

    2015-06-01

    Phosphorylation of sodium alginate salt (NaAlg) was carried out using H3PO4/P2O5/Et3PO4 followed by acid-base reaction with Ca(OAc)2 to give phosphorylated alginic acid calcium complexes (CaPAlg), as a water dispersible alginic acid derivative. The modified alginate derivatives including phosphorylated alginic acid (PAlg) and CaPAlg were characterized by nuclear magnetic resonance spectroscopy for (1)H, and (31)P nuclei, high resolution inductively coupled plasma optical emission spectroscopy, Fourier transform infrared spectroscopy, and thermogravimetric analysis. CaPAlg hydrogels were prepared simply by mixing CaPAlg solution (2w/v%) with NaAlg solution (2w/v%) in various ratios (2:8, 4:6, 6:4, 8:2) of volume. No additional calcium salts such as CaSO4 or CaCl2 were added externally. The gelation was completed within about 3-40min indicating a high potential of hydrogel delivery by injection in vivo. Their mechanical properties were tested to be ≤6.7kPa for compressive strength at break and about 8.4kPa/mm for elastic modulus. SEM analysis of the CaPAlg hydrogels showed highly porous morphology with interconnected pores of width in the range of 100-800μm. Cell culture results showed that the injectable hydrogels exhibited comparable properties to the pure alginate hydrogel in terms of cytotoxicity and 3D encapsulation of cells for a short time period. The developed injectable hydrogels showed suitable physicochemical and mechanical properties for injection in vivo, and could therefore be beneficial for the field of soft tissue engineering.

  10. Engineered magnetic core-shell SiO2/Fe microspheres and "medusa-like" microspheres of SiO2/iron oxide/carbon nanofibers or nanotubes.

    PubMed

    Mero, On; Sougrati, Moulay-Tahar; Jumas, Jean-Claude; Margel, Shlomo

    2014-08-19

    Iron oxide (IO) thin coatings of controlled thickness on SiO2 microspheres of narrow size distribution were prepared by decomposition at 160 °C of triiron dodecacarbonyl onto silica microspheres dispersed in diethylene glycol diethyl ether free of surfactant or stabilizer. The dried washed SiO2/IO core-shell microspheres were annealed at different temperatures and time periods under inert (Ar) or reducing (H2) atmosphere. The effect of temperature on the chemical composition, morphology, crystallinity, and magnetic properties of the IO and the elemental Fe nanoparticles type coatings onto the SiO2 core microspheres has been elucidated. "Medusa-like" SiO2/IO/carbon nanofibers and tubes particles were prepared by CVD of ethylene on the surface of the SiO2/IO microspheres at different temperatures. The morphology change of the grafted carbon nanofibers and tubes as a function of the CVD temperature was also elucidated.

  11. BIOCOMPATIBLE FLUORESCENT MICROSPHERES: SAFE PARTICLES FOR MATERIAL PENETRATION STUDIES

    SciTech Connect

    Farquar, G; Leif, R

    2009-07-15

    Biocompatible polymers with hydrolyzable chemical bonds have been used to produce safe, non-toxic fluorescent microspheres for material penetration studies. The selection of polymeric materials depends on both biocompatibility and processability, with tailored fluorescent properties depending on specific applications. Microspheres are composed of USFDA-approved biodegradable polymers and non-toxic fluorophores and are therefore suitable for tests where human exposure is possible. Micropheres were produced which contain unique fluorophores to enable discrimination from background aerosol particles. Characteristics that affect dispersion and adhesion can be modified depending on use. Several different microsphere preparation methods are possible, including the use of a vibrating orifice aerosol generator (VOAG), a Sono-Tek atomizer, an emulsion technique, and inkjet printhead. Applications for the fluorescent microspheres include challenges for biodefense system testing, calibrants for biofluorescence sensors, and particles for air dispersion model validation studies.

  12. Poly(methyl methacrylate)-grafted chitosan microspheres for controlled release of ampicillin.

    PubMed

    Changerath, Radhakumary; Nair, Prabha D; Mathew, Suresh; Nair, C P Reghunadhan

    2009-04-01

    Microspheres of 50-500 microm diameter were prepared from a blend of chitosan and chitosan-g-PMMA. Environmental scanning electron microscopic and SEM studies revealed that the microspheres are porous and the pores extend toward the inner core of the microspheres. The microspheres were also found to be hemocompatible and cytocompatible. A model drug ampicillin was used to evaluate the drug loading capacity and the controlled release properties of the microspheres. The system maintained a sustained release of ampicillin for a period of more than 8 days. The drug-loaded chitosan/chitosan-g-PMMA microspheres exhibited higher antibacterial activity for both the gram positive (ATCC 25923 S. aureus) and gram negative (ATCC 25922 E. coli) bacteria than the drug-loaded virgin chitosan microspheres. The percentage release and bioactivity of ampicillin was found to be higher for the chitosan/chitosan-g-PMMA microspheres than the virgin chitosan microspheres. Potential applications such as oral drug delivery, wound dressings, tissue engineering, and so forth, are envisaged from these microspheres.

  13. Characterization of an extracellular biofunctional alginate lyase from marine Microbulbifer sp. ALW1 and antioxidant activity of enzymatic hydrolysates.

    PubMed

    Zhu, Yanbing; Wu, Liyun; Chen, Yanhong; Ni, Hui; Xiao, Anfeng; Cai, Huinong

    2016-01-01

    A novel alginate-degrading marine bacterium Microbulbifer sp. ALW1 was isolated from rotten brown alga. An extracellular alginate lyase was purified to electrophoretic homogeneity and had a molecular mass of about 26.0 kDa determined by SDS-PAGE and size exclusion chromatography. This enzyme showed activities towards both polyguluronate and polymannuronate indicating its bifunctionality while with preference for the former substrate. Using sodium alginate as a substrate, strain ALW1 alginate lyase was optimally active at 45 °C and pH 7.0. It was stable at 25 °C, 30 °C, 35 °C and 40 °C, but not stable at 50 °C. This alginate lyase showed good stability over a broad pH range (5.0-9.0). The enzyme activity was increased to 5.1 times by adding NaCl to a final concentration of 0.5M. Strain ALW1 alginate lyase produced disaccharide (majority) and trisaccharide from alginate indicating that this enzyme could be a good tool for preparation of alginate oligosaccharides with low degree of polymerization (DP). The alginate oligosaccharides displayed the scavenging abilities towards radicals (DPPH, ABTS(+) and hydroxyl) and the reducing power. Therefore, the hydrolysates exhibited the antioxidant activity and had potential as a natural antioxidant.

  14. Facile large-scale preparation of mesoporous silica microspheres with the assistance of sucrose and their drug loading and releasing properties.

    PubMed

    Bi, Yanping; Wu, Chaonan; Xin, Ming; Bi, Shuyan; Yan, Chengxin; Hao, Jifu; Li, Fei; Li, Shou

    2016-03-16

    Mesoporous silica microspheres (MSMs) with a pore-size larger than 10nm and a large pore-volume have attracted considerable attention for their application in delivering poorly water-soluble drugs. Here we developed a simple method for large-scale synthesis of MSMs using sodium silicate as silica precursor. The novelty of this approach lies in the use of sucrose solution to achieve large size and volume of nanopores. The highest values of pore size and pore volume are 13.2 nm and 1.97 cm(3)/g, respectively. Importantly, the method is reliable and easily upscalable. The blank and drug-loaded MSMs were characterized by differential scanning calorimetry (DSC) and X-ray powder diffraction (XRPD). Ibuprofen and resveratrol were successfully loaded into the nanopores of MSMs in amorphous and nanocrystalline form and showed high drug-loadings and enhanced dissolution rates. This kind of MSMs appears to be a promising candidate as a new oral drug delivery vehicle providing a rapid drug release.

  15. Preparation of molecular imprinted microspheres based on inorganic-organic co-functional monomer for miniaturized solid-phase extraction of fluoroquinolones in milk.

    PubMed

    Wang, Hui; Wang, Ruiling; Han, Yehong

    2014-02-15

    An inorganic-organic co-functional monomer, methacrylic acid-vinyltriethoxysilan (MAA-VTES) was designed for the synthesis of molecularly imprinted microspheres (MIMs). By virtue of the aqueous suspension polymerization and dummy template (pazufloxacin), the obtained MAA-VTES based MIMs exhibited good recognition and selectivity to fluoroquinolones (FQs), and were successfully applied as selective sorbents of a miniaturized home-made solid phase extraction device for the determination of ofloxacin (OFL), lomefloxacin (LOM) and ciprofloxacin (CIP) in milk samples. Under the optimum conditions of the miniaturized molecularly imprinted solid phase extraction (mini-MISPE) coupled with liquid chromatography-ultraviolet detector (LC-UV), good linearities were obtained for three FQs in a range of 0.2-20.0μgmL(-1) and the average recoveries at three spiked levels were ranged from 87.2% to 106.1% with the relative standard deviation (RSD) less than 5.4%. The presented co-functional monomer based mini-MISPE-LC-UV protocol introduced the rigidity and flexibility of inorganic silicon materials, exhibited excellent extraction performance towards targets, and could be potentially applied to the determination of FQs in milk samples.

  16. INVESTIGATION OF DRUG RELEASE FROM BIODEGRADABLE PLG MICROSPHERES: EXPERIMENT AND THEORY

    SciTech Connect

    ANDREWS, MALCOLM J.; BERCHANE, NADER S.; CARSON, KENNETH H.; RICE-FICHT, ALLISON C.

    2007-01-30

    Piroxicam containing PLG microspheres having different size distributions were fabricated, and in vitro release kinetics were determined for each preparation. Based on the experimental results, a suitable mathematical theory has been developed that incorporates the effect of microsphere size distribution and polymer degradation on drug release. We show from in vitro release experiments that microsphere size has a significant effect on drug release rate. The initial release rate decreased with an increase in microsphere size. In addition, the release profile changed from first order to concave-upward (sigmoidal) as the system size was increased. The mathematical model gave a good fit to the experimental release data.

  17. Facile fabrication of various zinc-nickel citrate microspheres and their transformation to ZnO-NiO hybrid microspheres with excellent lithium storage properties

    NASA Astrophysics Data System (ADS)

    Xie, Qingshui; Ma, Yating; Zeng, Deqian; Wang, Laisen; Yue, Guanghui; Peng, Dong-Liang

    2015-02-01

    Zinc-nickel citrate microspheres are prepared by a simple aging process of zinc citrate solid microspheres in nickel nitrate solution. As the concentration of nickel nitrate solution increases, the morphology of the produced zinc-nickel citrate evolves from solid, yolk-shell to hollow microspheres. The formation mechanism of different zinc-nickel citrate microspheres is discussed. After annealing treatment of the corresponding zinc-nickel citrate microspheres in air, three different ZnO-NiO hybrid architectures including solid, yolk-shell and hollow microspheres can be successfully fabricated. When applied as the anode materials for lithium ion batteries, ZnO-NiO hybrid yolk-shell microspheres demonstrate the best electrochemical properties than solid and hollow counterparts. After 200th cycles, ZnO-NiO hybrid yolk-shell microspheres deliver a high reversible capacity of 1176 mA h g-1. The unique yolk-shell configuration, the synergetic effect between ZnO and NiO and the catalytic effect of metal Ni generated by the reduction of NiO during discharging process are responsible for the excellent lithium storage properties of ZnO-NiO hybrid yolk-shell microspheres.

  18. Evaluation of the Thermosensitive Release Properties of Microspheres Containing an Agrochemical Compound.

    PubMed

    Terada, Takatoshi; Ohtsubo, Toshiro; Iwao, Yasunori; Noguchi, Shuji; Itai, Shigeru

    2017-01-01

    The purpose of this study was to develop a deeper understanding of the key physicochemical parameters involved in the release profiles of microsphere-encapsulated agrochemicals at different temperatures. Microspheres consisting of different polyurethanes (PUs) were prepared using our previously reported solventless microencapsulation technique. Notably, these microspheres exhibited considerable differences in their thermodynamic characteristics, including their glass transition temperature (Tg), extrapolated onset temperature (To) and extrapolated end temperature (Te). At test temperatures below the To of the PU, only 5-10% of the agrochemical was rapidly released from the microspheres within 1 d, and none was released thereafter. However, at test temperatures above the To of the PU, the rate of agrochemical release gradually increased with increasing temperatures, and the rate of release from the microspheres was dependent on the composition of the PU. Taken together, these results show that the release profiles of the microspheres were dependent on their thermodynamic characteristics and changes in their PU composition.

  19. Raspberry-like PS/CdTe/Silica Microspheres for Fluorescent Superhydrophobic Materials.

    PubMed

    Chang, Jinghui; Zang, Linlin; Wang, Cheng; Sun, Liguo; Chang, Qing

    2016-12-01

    Superhydrophobic particulate films were fabricated via deposition of raspberry-like fluorescent PS/CdTe/silica microspheres on clean glass substrates and surface modification. Particularly, the fluorescent microspheres were prepared by a kind of modified strategy, namely introducing poly (acrylic acid)-functionalized polystyrene microspheres and thiol-stabilized CdTe quantum dots into a hydrolysis reaction of tetraethoxysilane simultaneously. And through adjusting the reaction parameters, the polystyrene spheres with two particle sizes and three colors of CdTe quantum dots aqueous solution were obtained. Consequently, raspberry-like microspheres consist of polystyrene cores and the composite shells of CdTe quantum dots and silica. These microspheres possess a fluorescent characteristic and form a hierarchical dual roughness which was conductive to superhydrophobicity, and the hydrophobic tests also showed the contact angles of water droplets on the surface of the raspberry-like microspheres which were over 160° at room temperature.

  20. Use of spray-dried zirconia microspheres in the separation of immunoglobulins from cell culture supernatant.

    PubMed

    Subramanian, A; Carr, P W; McNeff, C V

    2000-08-18

    A method suitable for the isolation of monoclonal antibodies (MAbs) on novel zirconia microspheres (20-30 microm) is described. Zirconia microspheres were generated by spray drying colloidal zirconia. Spray-dried zirconia microspheres were further classified and characterized by X-ray diffraction, BET porosimetry and scanning electron microscopy. Spray-dried zirconia microspheres were modified with ethylenediamine-N,N'-tetra(methylenephosphonic) acid (EDTPA) to create a cation-exchange chromatographic support. The chromatographic behavior of a semi-preparative column packed with EDTPA-modified zirconia microspheres was evaluated and implications for scale-up are provided. EDTPA-modified zirconia microspheres were further used to purify MAbs from cell culture supernatant. Analysis by enzyme linked immunosorbent assay and gel electrophoresis demonstrate that MAbs can be recovered from a cell culture supernatant at high yield (92-98%) and high purity (>95%) in a single chromatographic step.

  1. Raspberry-like PS/CdTe/Silica Microspheres for Fluorescent Superhydrophobic Materials

    NASA Astrophysics Data System (ADS)

    Chang, Jinghui; Zang, Linlin; Wang, Cheng; Sun, Liguo; Chang, Qing

    2016-02-01

    Superhydrophobic particulate films were fabricated via deposition of raspberry-like fluorescent PS/CdTe/silica microspheres on clean glass substrates and surface modification. Particularly, the fluorescent microspheres were prepared by a kind of modified strategy, namely introducing poly (acrylic acid)-functionalized polystyrene microspheres and thiol-stabilized CdTe quantum dots into a hydrolysis reaction of tetraethoxysilane simultaneously. And through adjusting the reaction parameters, the polystyrene spheres with two particle sizes and three colors of CdTe quantum dots aqueous solution were obtained. Consequently, raspberry-like microspheres consist of polystyrene cores and the composite shells of CdTe quantum dots and silica. These microspheres possess a fluorescent characteristic and form a hierarchical dual roughness which was conductive to superhydrophobicity, and the hydrophobic tests also showed the contact angles of water droplets on the surface of the raspberry-like microspheres which were over 160° at room temperature.

  2. Gingival Mesenchymal Stem Cell (GMSC) Delivery System Based on RGD-Coupled Alginate Hydrogel with Antimicrobial Properties: A Novel Treatment Modality for Peri-Implantitis

    PubMed Central

    Diniz, Ivana M. A.; Chen, Chider; Ansari, Sahar; Zadeh, Homayoun H.; Moshaverinia, Maryam; Chee, Daniel; Marques, Márcia M.; Shi, Songtao; Moshaverinia, Alireza

    2015-01-01

    Purpose Peri-implantitis is one of the most common inflammatory complications in dental implantology. Similar to periodontitis, in peri-implantitis, destructive inflammatory changes take place in the tissues surrounding a dental implant. Bacterial flora at the failing implant sites resemble the pathogens in periodontal disease and consist of Gram-negative anaerobic bacteria including Aggregatibacter actinomycetemcomitans (Aa). Here we demonstrate the effectiveness of a silver lactate (SL)-containing RGD-coupled alginate hydrogel scaffold as a promising stem cell delivery vehicle with antimicrobial properties. Materials and Methods Gingival mesenchymal stem cells (GMSCs) or human bone marrow mesenchymal stem cells (hBMMSCs) were encapsulated in SL-loaded alginate hydrogel microspheres. Stem cell viability, proliferation, and osteo-differentiation capacity were analyzed. Results Our results showed that SL exhibited antimicrobial properties against Aa in a dose-dependent manner, with 0.50 mg/ml showing the greatest antimicrobial properties while still maintaining cell viability. At this concentration, SL-containing alginate hydrogel was able to inhibit Aa on the surface of Ti discs and significantly reduce the bacterial load in Aa suspensions. Silver ions were effectively released from the SL-loaded alginate microspheres for up to 2 weeks. Osteogenic differentiation of GMSCs and hBMMSCs encapsulated in the SL-loaded alginate microspheres were confirmed by the intense mineral matrix deposition and high expression of osteogenesis-related genes. Conclusion Taken together, our findings confirm that GMSCs encapsulated in RGD-modified alginate hydrogel containing SL show promise for bone tissue engineering with antimicrobial properties against Aa bacteria in vitro. PMID:26216081

  3. Bone regeneration potential of stem cells derived from periodontal ligament or gingival tissue sources encapsulated in RGD-modified alginate scaffold.

    PubMed

    Moshaverinia, Alireza; Chen, Chider; Xu, Xingtian; Akiyama, Kentaro; Ansari, Sahar; Zadeh, Homayoun H; Shi, Songtao

    2014-02-01

    Mesenchymal stem cells (MSCs) provide an advantageous alternative therapeutic option for bone regeneration in comparison to current treatment modalities. However, delivering MSCs to the defect site while maintaining a high MSC survival rate is still a critical challenge in MSC-mediated bone regeneration. Here, we tested the bone regeneration capacity of periodontal ligament stem cells (PDLSCs) and gingival mesenchymal stem cells (GMSCs) encapsulated in a novel RGD- (arginine-glycine-aspartic acid tripeptide) coupled alginate microencapsulation system in vitro and in vivo. Five-millimeter-diameter critical-size calvarial defects were created in immunocompromised mice and PDLSCs and GMSCs encapsulated in RGD-modified alginate microspheres were transplanted into the defect sites. New bone formation was assessed using microcomputed tomography and histological analyses 8 weeks after transplantation. Results confirmed that our microencapsulation system significantly enhanced MSC viability and osteogenic differentiation in vitro compared with non-RGD-containing alginate hydrogel microspheres with larger diameters. Results confirmed that PDLSCs were able to repair the calvarial defects by promoting the formation of mineralized tissue, while GMSCs showed significantly lower osteogenic differentiation capability. Further, results revealed that RGD-coupled alginate scaffold facilitated the differentiation of oral MSCs toward an osteoblast lineage in vitro and in vivo, as assessed by expression of osteogenic markers Runx2, ALP, and osteocalcin. In conclusion, these results for the first time demonstrated that MSCs derived from orofacial tissue encapsulated in RGD-modified alginate scaffold show promise for craniofacial bone regeneration. This treatment modality has many potential dental and orthopedic applications.

  4. 21 CFR 582.7187 - Calcium alginate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Calcium alginate. 582.7187 Section 582.7187 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Calcium alginate. (a) Product. Calcium alginate. (b) Conditions of use. This substance is...

  5. 21 CFR 582.7133 - Ammonium alginate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Ammonium alginate. 582.7133 Section 582.7133 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Ammonium alginate. (a) Product. Ammonium alginate. (b) Conditions of use. This substance is...

  6. 21 CFR 582.7610 - Potassium alginate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 6 2012-04-01 2012-04-01 false Potassium alginate. 582.7610 Section 582.7610 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Potassium alginate. (a) Product. Potassium alginate. (b) Conditions of use. This substance is...

  7. 21 CFR 582.7610 - Potassium alginate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 6 2014-04-01 2014-04-01 false Potassium alginate. 582.7610 Section 582.7610 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Potassium alginate. (a) Product. Potassium alginate. (b) Conditions of use. This substance is...

  8. 21 CFR 582.7610 - Potassium alginate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Potassium alginate. 582.7610 Section 582.7610 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Potassium alginate. (a) Product. Potassium alginate. (b) Conditions of use. This substance is...

  9. 21 CFR 582.7610 - Potassium alginate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 6 2013-04-01 2013-04-01 false Potassium alginate. 582.7610 Section 582.7610 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Potassium alginate. (a) Product. Potassium alginate. (b) Conditions of use. This substance is...

  10. 21 CFR 582.7610 - Potassium alginate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Potassium alginate. 582.7610 Section 582.7610 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Potassium alginate. (a) Product. Potassium alginate. (b) Conditions of use. This substance is...

  11. 21 CFR 582.7724 - Sodium alginate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 6 2013-04-01 2013-04-01 false Sodium alginate. 582.7724 Section 582.7724 Food... DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Stabilizers § 582.7724 Sodium alginate. (a) Product. Sodium alginate. (b) Conditions of use. This substance is generally recognized...

  12. 21 CFR 582.7724 - Sodium alginate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Sodium alginate. 582.7724 Section 582.7724 Food... DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Stabilizers § 582.7724 Sodium alginate. (a) Product. Sodium alginate. (b) Conditions of use. This substance is generally recognized...

  13. 21 CFR 582.7724 - Sodium alginate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 6 2014-04-01 2014-04-01 false Sodium alginate. 582.7724 Section 582.7724 Food... DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Stabilizers § 582.7724 Sodium alginate. (a) Product. Sodium alginate. (b) Conditions of use. This substance is generally recognized...

  14. 21 CFR 582.7724 - Sodium alginate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Sodium alginate. 582.7724 Section 582.7724 Food... DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Stabilizers § 582.7724 Sodium alginate. (a) Product. Sodium alginate. (b) Conditions of use. This substance is generally recognized...

  15. 21 CFR 582.7724 - Sodium alginate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 6 2012-04-01 2012-04-01 false Sodium alginate. 582.7724 Section 582.7724 Food... DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Stabilizers § 582.7724 Sodium alginate. (a) Product. Sodium alginate. (b) Conditions of use. This substance is generally recognized...

  16. 21 CFR 184.1011 - Alginic acid.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Alginic acid. 184.1011 Section 184.1011 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN... Substances Affirmed as GRAS § 184.1011 Alginic acid. (a) Alginic acid is a colloidal,...

  17. 21 CFR 184.1011 - Alginic acid.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Alginic acid. 184.1011 Section 184.1011 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) DIRECT FOOD....1011 Alginic acid. (a) Alginic acid is a colloidal, hydrophilic polysaccharide obtained from...

  18. 21 CFR 184.1011 - Alginic acid.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Alginic acid. 184.1011 Section 184.1011 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN... Substances Affirmed as GRAS § 184.1011 Alginic acid. (a) Alginic acid is a colloidal,...

  19. 21 CFR 184.1011 - Alginic acid.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Alginic acid. 184.1011 Section 184.1011 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN... Substances Affirmed as GRAS § 184.1011 Alginic acid. (a) Alginic acid is a colloidal,...

  20. 21 CFR 184.1011 - Alginic acid.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Alginic acid. 184.1011 Section 184.1011 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN... Substances Affirmed as GRAS § 184.1011 Alginic acid. (a) Alginic acid is a colloidal,...

  1. Novel copper (II) alginate hydrogels and their potential for use as anti-bacterial wound dressings.

    PubMed

    Klinkajon, Wimonwan; Supaphol, Pitt

    2014-08-01

    The incorporation of a metal ion, with antimicrobial activity, into an alginate dressing is an attractive approach to minimize infection in a wound. In this work, copper (II) cross-linked alginate hydrogels were successfully prepared using a two-step cross-linking procedure. In the first step, solid alginate films were prepared using a solvent-casting method from soft gels of alginate solutions that had been lightly cross-linked using a copper (II) (Cu(2+)) sulfate solution. In the second step, the films were further cross-linked in a corresponding Cu(2+) sulfate solution using a dipping method to further improve their dimensional stability. Alginate solution (at 2%w/v) and Cu(2+) sulfate solution (at 2%w/v) in acetate buffer at a low pH provided soft films with excellent swelling behavior. An increase in either Cu(2+) ion concentration or cross-linking time led to hydrogels with more densely-cross-linked networks that limited water absorption. The hydrogels clearly showed antibacterial activity against Escherichia coli, Staphylococcus aureus, methicillin-resistant Staphylococcus aureus (MRSA), Staphylococcus epidermidis and Streptococcus pyogenes, which was proportional to the Cu(2+) ion concentration. Blood coagulation studies showed that the tested copper (II) cross-linked alginate hydrogels had a tendency to coagulate fibrin, and possibly had an effect on pro-thrombotic coagulation and platelet activation. Conclusively, the prepared films are likely candidates as antibacterial wound dressings.

  2. Efficient functionalization of alginate biomaterials.

    PubMed

    Dalheim, Marianne Ø; Vanacker, Julie; Najmi, Maryam A; Aachmann, Finn L; Strand, Berit L; Christensen, Bjørn E

    2016-02-01

    Peptide coupled alginates obtained by chemical functionalization of alginates are commonly used as scaffold materials for cells in regenerative medicine and tissue engineering. We here present an alternative to the commonly used carbodiimide chemistry, using partial periodate oxidation followed by reductive amination. High and precise degrees of substitution were obtained with high reproducibility, and without formation of by-products. A protocol was established using l-Tyrosine methyl ester as a model compound and the non-toxic pic-BH3 as the reducing agent. DOSY was used to indirectly verify covalent binding and the structure of the product was further elucidated using NMR spectroscopy. The coupling efficiency was to some extent dependent on alginate composition, being most efficient on mannuronan. Three different bioac