Search Results

You are looking at 1 - 10 of 67 items for :

  • "microparticle" x
  • Refine by Access: All Content x
Clear All

Abstract  

Microencapsulation of Lippia sidoides essential oil was carried out by spray drying. Blends of maltodextrin and gum arabic were used as carrier. Spray dried microparticles were characterized using conventional (thermogravimetry, evolved gas analysis) and combined (thermogravimetry-mass spectrometry analysis) thermal analysis techniques in order to evaluate the abilities of carriers with different compositions in retaining and in releasing the core vs. dynamic heating. Thermal analysis was useful to evaluate the physico-chemical interactions between the core and carriers and to determine the protective effect of the carriers on the evaporation of essential oil.

Restricted access

T Jha 1996 Development of indomethacin and ibuprofen loaded polymethylmethacrylate microparticles Pharm Sci 2 209 213

Restricted access
Journal of Flow Chemistry
Authors: Christophe A. Serra, Ikram U. Khan, ZhenQi Chang, Michel Bouquey, René Muller, Isabelle Kraus, Marc Schmutz, Thierry Vandamme, Nicolas Anton, Christian Ohm, Rudolf Zentel, Andrea Knauer, and Michael Köhler

Abstract

Capillary-based flow-focusing and co-flow microsystems were developed to produce sphere-like polymer microparticles of adjustable sizes in the range of 50 to 600 μm with a narrow size distribution (CV < 5%) and different morphologies (core-shell, janus, and capsules). Rod-like particles whose length was conveniently adjusted between 400 μm and few millimeters were also produced using the same microsystems. Influence of operating conditions (flow rate of the different fluid, microsystem characteristic dimensions, and design) as well as material parameters (viscosity of the different fluids and surface tension) was investigated. Empirical relationships were thus derived from experimental data to predict the microparticle's overall size, shell thickness, or rods length. Besides morphology, microparticles with various compositions were synthesized and their potential applications highlighted: drug-loaded microparticles for new drug delivery strategies, composed inorganic-organic multiscale microparticles for sensorics, and liquid crystalline elastomer microparticles showing an anisotropic reversible shape change upon temperature for thermal actuators or artificial muscles.

Restricted access

Abstract  

The nuclear track technique (NTT) is used to enhance the porosity of silica micro-particles. The enhanced porosity is a result of the formation of surface and interior pores or tracks in the silica by the action of external and internal fission fragments. The fission tracks produced at the surface and within the interior of the micro-particles are a result of coating the particles with trace quantitities of uranium, instead of having trace quantities of uranium incorporated within the silica matrix.

Restricted access
Journal of Radioanalytical and Nuclear Chemistry
Authors: Shen Rongsen, Wang Renzhi, Xing Ruiyun, Li Yingoi, Zhou Fengqi, Jiang Shaohua, Lin Zhihao, and Xu Banglei

Abstract  

Three types of magnetic microparticle antibodies were developed: 1) magnetic second antibody I (MSA-I) where the antibody molecules were directly immobilized by physical adsorption on Fe3O4 microparticles (magnetic nucleus, MN) 10nm±34% in diameter, 2) magnetic second antibody II (MSA-II) where the antibody molecules were immobilized by chemical coupling on the MN coated with polyacrolein, and 3) magnetic, first antibody (MFA-T3) where the anti-T3 antibody molecules were specifically immobilized by immunoadsorption to the second antibody molecules of the MSA-II. The optimal conditions for their preparation were elaborated. Some physical, chemical and immunological characteristics of these magnetic microparticles were described. The application of the MSA-I, MSA-II and MFA-T3 to RIAs for evaluation of thyroid function, such as triiodothyronine (T3), reverse T3(rT3), free T3 (fT3), thyroxine (T4), free T4(fT4), thyroid-stimulating hormone (TSH), thyroglobulin (TG) and TG-antibody (TG-Ab), etc., was reported.

Restricted access

Abstract  

Chitosan microparticles were prepared with the purpose of incorporating all-trans retinoic acid (ATRA). Morphology, drug content, release behavior and the interaction between chitosan and ATRA were investigated. Chitosan microparticles presented irregular and rough surface and drug content of 47±3%. The results of DSC and IR spectroscopy demonstrated interaction between drug and polymer resulting from retinoate or retinoamide formation. The drug release study showed that approximately 90% of drug was not released from microparticles until the end of experiment (48 h). That release behavior was probably due to the strong drug–polymer interaction and the more compact network of microparticles formed.

Restricted access

Abstract  

The detection of radiocesium in microparticles was performed by using an ion trap mass spectrometer coupled with laser desorption and ionization. Pulsed laser desorbed particle and the resulted ions were analyzed by an ion trap mass analyzer. The presence of radiocesium, especially about137Cs, in microparticles was verified by single as well as successive particle analysis. The detection limit was reached to ≈ag/particle level with a signal-to-background ratio of 4. The inhomogeneous distribution of particle size and the irregular shapes of particle limit the quantitative evaluation of137Cs concentration in the microparticle. But this high sensitivity allows to monitor directly the radiocesium from small amounts of a microparticle sample.

Restricted access

Summary Thermally carbonised mesoporous silicon microparticles were produced and loaded with two active pharmaceutical ingredients, ibuprofen and antipyrine. By combining the results measured with TG and DSC, reliable estimations for the degrees of the drug loads were obtained. To distinguish the drug adsorbed on the surfaces of the microparticles from that absorbed into the pores, the principle of thermoporometry on the DSC measurements was employed. According to the principle, the drug held in the capillaries of porous material has a depressed melting temperature because of the higher pressure of the drug in cavities with a curved interface. On the other hand, the drug located on the external surface of the microparticles exhibits the normal melting of bulk drug. The loading degrees obtained with the thermoanalytical methods (31 and 26 mass& for ibuprofen and antipyrine, respectively) were comparable with the results obtained with helium pycnometry (the corresponding values were 33 and 28 mass&). Nitrogen sorption studies were not reliable for quantitative determinations due to the inability of nitrogen to penetrate in all pores, which might be blocked by the drug on the surface of the microparticles.

Restricted access

Abstract  

We have described Magnetic Microparticle Antibodies and Their Application to RIAs in a recently published paper1. In this article operative parameters for the preparation of a magnetic second antibody (MSA-II) including results of purification of donky anti-rabbit (DxR) serum by an (NH4)2SO4 precipitation method, rates of recovery of products in preparation of magnetic nucleus (MN, Fe3O4 microparticle), in distillation of acrolein (AL) and in preparation of polyacrolein magnetic particle (PAMP), change in pH value of suspension irradiated before and after60Co -irradiation and volume of wet sediment in separation of magnetic particles by a magnetic separator, etc., as well as correlation of levels of quality control (QC) sera obtained with liquid-phase double antibody assay (LDA) and MSA-II assay during four years were supplementarily summarized. These operative parameters would be helpful to mastering the procedures for preparation and/or use of the magnetic particles. The better correlation of levels of QC sera for both the assays showed the reliability of the magnetic antibody.

Restricted access
Journal of Flow Chemistry
Authors: L. Zane Miller, James J. Rutowski, Jonathan A. Binns, Guillermo Orts-Gil, D. Tyler McQuade, and Jeremy L. Steinbacher

We present a rapid approach for forming monodisperse silica microcapsules decorated with metal oxide nanoparticles; the silica–metal oxide composites have a hierarchical architecture and a range of compositions. The details of the method were defined using titania precursors. Silica capsules containing low concentrations of titania (<1 wt. %) were produced via an interfacial reaction using a simple mesofluidic T-junction droplet generator. Increasing the titania content of the capsules was achieved using two related, flow-based postsynthetic approaches. In the first approach, a precursor solution containing titanium alkoxides was flowed through a packed-bed of capsules. The second approach provided the highest concentration of titania (3.5 wt. %) and was achieved by evaporating titanium precursor solutions onto a capsule packed-bed using air flow to accelerate evaporation. Decorated capsules, regardless of the method, were annealed to improve the titania crystallinity and analyzed by optical microscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDX), powder X-ray diffraction (PXRD), and Fourier transform infrared (FT-IR) spectroscopy. The photocatalytic properties were then compared to a commercial nanoparticulate titania, which the microcapsule-supported titania outperformed in terms of rate of degradation of an organic dye and recyclability. Finally, the generality of the flow-based surface decoration procedures was demonstrated by synthesizing several composite transition metal oxide–silica microparticle materials.

Restricted access