Yield Of Microcapsules Research Articles

Preparation and application of microcapsule-encapsulated color electrophortic fluid in Isopar M system for electrophoretic display

The use of Isopar M as a liquid suspending fluid for electrophoretic display was studied. The dispersion stability and chargeability of pigments suspended in Isopar M were investigated. Polyisobutylene monosuccinimide (T-151) as the charge control additive in Isopar M electrophoretic fluid can provide a good electrophoretic mobility to the particles. The wall materials of a series of blue–white, red–white and yellow–white dual-particle microcapsules were prepared by in situ polymerization of urea and formaldehyde. The mass ratio of wall/core material was a key factor in influencing the yield of microcapsules. The concentration of resorcinol has an impact on the surface morphology and mechanical strength of microcapsule wall. Microcapsules’ surface morphologies were characterized by optical microscopy and scanning electron microscopy. The performance of the microcapsules with different binder materials and adhesive layers were investigated. Contrast ratio of microcapsules display device were tested every 10days for a period of 90days. The compatibility of Isopar M with both the electrophoretic particles and bounding capsule was studied.

Gelatin/carboxymethylcellulose/dioctyl sulfosuccinate sodium microcapsule by complex coacervation and its application for electrophoretic display

We have described the microcapsules containing electrophoretic fluid as core material, prepared from gelatin, sodium carboxymethylcellulose (NaCMC) and dioctyl sulfosuccinate sodium (DSS) by complex coacervation method. The gelatin/NaCMC/DSS microcapsules are characterized by optical microscopy (OM), scanning electron microscopy (SEM), particle size analysis and thermogravimetric analysis (TGA). It is found that DSS plays an important role in the formation of the microcapsule wall and the concentration of DSS deeply affects the yield of microcapsules by enhancing the interaction between gelatin and NaCMC. The microcapsules prepared with DSS content of 0.6 mM show compact capsule wall which endows the capsules with good barrier property and high thermal stability. These microcapsules are applied successfully to prepare a 4-in. clock display panel controlled by single-chip microprocessor (SCM) operated at a low direct current (DC) voltage of 3 V, demonstrating that these microcapsules are potential for the applications in the area of electrophoretic displays.

Development of Biodegradable Microcapsules as Carrier for Oral Controlled Delivery of Amifostine

ABSTRACTThe primary objective of this project was to develop a biodegradable, orally active controlled-release formulation of amifostine. Development of such a formulation will mark an important advancement in the areas of chemoprotection and radioprotection. Biodegradable microcapsules of amifostine were prepared using poly(lactide/glycolide) (PLGA 50:50). The microcapsules were prepared by solvent evaporation technique. Amifostine-loaded microcapsules were evaluated for particle size, surface morphology, thermal characteristics, and drug release. Particle size and surface morphology were determined using scanning electron microscopy (SEM). Thermal characterization was conducted using differential scanning calorimetry (DSC). In vitro release study was performed at 37°C using phosphate buffer (pH 7.4). Amifostine release was calculated by measuring the amount of drug remaining within the microcapsules at a specific sampling time. The amount of amifostine in the samples was determined by high-performance liquid chromatography (HPLC) using an electrochemical detector. The yield of microcapsules was 75%. Scanning electron microscopy pictures revealed that the particles were nearly spherical and smooth with an average size of 54 µm. Differential scanning calorimetry thermograms showed that microcapsules loaded with amifostine have a glass transition at 39.4°C, and the melting endotherm of amifostine was absent. The absence of a melting endotherm for amifostine was an indication that amifostine was not in the crystalline state in the microcapsules, but rather in the form of a solid solution in PLGA. Approximately 50% amifostine was released during the first 6 hr of the in vitro release study. The drug, however, continued to release over the observed period of 12 hr during which 92% amifostine was released.

Preparation of biodegradable microcapsules containing zidovudine (AZT) using solvent evaporation technique.

Sustained release biodegradable microcapsules of AZT were prepared using different concentrations of copolymer of poly(lactic/glycolic) acid (PLGA 50:50 and PLGA 90:10). Solid microcapsules were collected following the complete evaporation of the solvent. The yield of microcapsules was increased two fold with a two-fold increase of the polymer concentration. The efficiency of encapsulation of AZT was also increased with the increase of the polymer concentration. These microcapsules were characterized using scanning electron microscopy. The dissolution of AZT from the microcapsules of PLGA (50: 50) was higher than the microcapsules of PLGA (90:10); the PLGA (50:50) microcapsules containing 1:10 drug/polymer ratio showed higher dissolution than the microcapsules containing 1:20 drug/polymer ratio. The PLGA (90:10) microcapsules containing 1:6 drug/polymer ratio showed higher dissolution than the microcapsules containing 1:10 drug/polymer ratio. In conclusion, the dissolution of AZT was dependent on the type of the copolymer used and the relative concentrations of the drug and the copolymer.

The effect of physical condition in first emulsification for yield of microcapsules (author's transl)

Ethyl cellulose microcapsules containing aqueous gelatin solution were prepared by the microencapsulation by a multiple (WI/O/WII) emulsion method. Some physical and dynamical factors that affect the formation of emulsion were examined and discussed in the first emulsification. Furthermore, the size, distribution and yield percentage of microcapsules were calculated. The mean length diameter of emulsion (WI/O) was clearly influenced by the viscosity ratio of the internal phase (μi) to the external phase (μe), and then it showed the minimum value at a characteristic viscosity ratio, μi/μe' near to 1.0. In the first emulsification stage, high yield of microcapsules were obtained in the following conditions : 1) Sufficient amounts of sodium sulfate to inhibit coacervation were added in an aqueous solution of gelatin. 2) The mixed solution was mechanically emulsified with a chemistirrer at the high revolution number as possible.

The effect of physical condition in second emulsification for yield of microcapsules (author's transl)

The effect of physical condition in second emulsification for yield of microcapsules (author's transl)