• Archives of Pharmacal Research
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• v.27 no.1
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• pp.1-12
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• 2004

Initial burst is one of the major challenges in protein-encapsulated microparticle systems. Since protein release during the initial stage depends mostly on the diffusional escape of the protein, major approaches to prevent the initial burst have focused on efficient encapsulation of the protein within the microparticles. For this reason, control of encapsulation efficiency and the extent of initial burst are based on common formulation parameters. The present article provides a literature review of the formulation parameters that are known to influence the two properties in the emulsion-solvent evaporation/extraction method. Physical and chemical properties of encapsulating polymers, solvent systems, polymer-drug interactions, and properties of the continuous phase are some of the influential variables. Most parameters affect encapsulation efficiency and initial burst by modifying solidification rate of the dispersed phase. In order to prevent many unfavorable events such as pore formation, drug loss, and drug migration that occur while the dispersed phase is in the semi-solid state, it is important to understand and optimize these variables.

• Journal of Pharmaceutical Investigation
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• v.40 no.6
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• pp.353-356
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• 2010

Although liposomes have been applied as drug delivery systems in various fields, the usage was limited due to the low encapsulation efficiency compared to other carrier systems. Here, cationic liposomes were prepared by mixing 1,2-dioleoyl-3-trimethylammoniopropane (DOTAP) as a cationic lipid, 1,2-dioleoyl-sn-glycerol-phosphoethanolamine (DOPE) and cholesterol (CH), and the liposomes were hydrated by varying the aqueous phases such as phosphate-buffered saline (PBS), 5% dextrose, and 10% sucrose in order to improve the encapsulation efficiency of bovine serum albumin (BSA). The particle size and zeta potential were determined by dynamic light scattering method and in vitro release patterns were investigated by spectrophotometry. Particle size and zeta potential of liposomes were varied depending on the ratio of DOTAP/DOPE/CH in range of 270-350 nm and 0.8-9.7 mV, respectively. Moreover, the addition of polyethylene glycol (PEG) improved the encapsulation efficiency from 37% to 43% as well as reduced particle sizes of liposomes while the liposomes were hydrated in PBS. When the liposomes were hydrated with 10% sucrose, the encapsulation efficiency of BSA was higher than any other groups. Whereas PBS was used as hydration solution, lower encapsulation efficiency was obtained compared with other groups. More than 60% of BSA was released from the liposomes hydrated with 10% sucrose; thereafter another 20% of BSA was released. Therefore, release pattern of BSA from cationic liposomes was extended release in this study. From the results, cationic liposomes dispersed in 10% sucrose would be potential carrier with high encapsulation efficiency.

• Bulletin of the Korean Chemical Society
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• v.29 no.10
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• pp.2005-2008
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• 2008

A cyclotetraphosphazene derivative with eight chains was synthesized from octachlorocyclotetraphosphazene. The vesicles were prepared using the cyclotetraphosphazene derivative and cholesterol. The resulting vesicles were characterized by TEM and measurements of their encapsulation efficiency. The stability of the vesicles was enhanced with the addition of dihexadecylphosphate. The size and the encapsulation efficiency of the vesicles changed according to the amount of cholesterol added. The size and the encapsulation efficiency of the vesicle were lowest when the mole ratio (cholesterol: the cyclophosphazene derivative) was 0.9.

• Journal of Pharmaceutical Investigation
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• v.37 no.1
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• pp.39-43
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• 2007

Previously, we have reported that PLGA nanoparticles were prepared for sustained release of water-soluble blue dextran and the particle size, in vitro release pattern and encapsulation were modulated by varying polymers. This study was designed to encapsulate plasmid DNA in PLGA nanoparticles and to investigate the effect of Polymers and temperatures. PLGA nanoparticles were fabricated with poloxamer 188 (P188) or poloxamer 407 (P407) by using spontaneous emulsification solvent diffusion method. As a model plasmid DNA, pCMV-Taq2B/1L-18 was encapsulated in PLGA nanoparticles. Then, the particle size, zeta potential and encapsulation efficiency of nanoparticles containing plasmid DNA were investigated. Particle sizes of PLGA nanoparticles prepared with P188 and P407 were in the range of 200-330 nm and 250-290 nm, respectively. Zeta potentials of nanoparticles were negative regardless of nanoparticle compositions. Encapsulation efficiency of P407 nanoparticles prepared at $30^{\circ}C$ was higher than those at other preparation condition. From the results, the PLGA nanoparticles prepared with poloxamers at different temperature, could modulate the particles size of nanoparticles, and encapsulation efficiency of plasmid DNA.

• 한국태양에너지학회:학술대회논문집
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• 2011.11a
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• pp.137-142
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• 2011

Individual solar cells must be connected together to give the appropriate current and voltage levels and they must also be protected from damage by the environment. [1] PV module consists of a glass/ polymer encapsulation/ solar cell string/ polymer encapsulation/ back sheet. Usually, encapsulation materials is used EVA(ethylene vinyl acetate), PVB(polyvinyl butyral), PO(polyolefin)sheet. This study is about fabrication of module using silicone material instead of above them. We got to know advantage that is fabrication time and efficiency of modules.

• Applied Chemistry for Engineering
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• v.35 no.2
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• pp.115-121
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• 2024

This study analyzed the influence of process variables affecting the thermodynamic equilibrium and fluid dynamics of interfaces such as reverse micelle, salt concentration, interfacial tension, and viscosity of fluids to optimize the microencapsulation process using the W1/O/W2 double emulsion method. The process variable with the greatest impact on encapsulation efficiency was found to be the difference in osmotic pressure between the W1 and W2 phases. It was observed that increasing the salt concentration in the W2 phase or decreasing the ascorbic acid concentration in the W1 phase resulted in higher encapsulation efficiency. Additionally, a larger difference in osmotic pressure led to increased damage to the surface of the microparticles, as confirmed by SEM images. The introduction of reverse micelles, which was anticipated to increase encapsulation efficiency, either had a low contribution or even decreased encapsulation efficiency. The yield of microcapsules was expressed as a universal function, applicable to all process conditions or solution compositions. According to this universal function, no further increase in yield was observed beyond the Ca (capillary number) of approximately 20.

• KSBB Journal
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• v.26 no.4
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• pp.333-340
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• 2011

In this study, gemcitabine-loaded methoxy poly(ethylene glycol)-b-poly(L-lactide) (MPEG-PLLA) microparticles with different PEG block lengths were prepared by a W/O/W double emulsion technique. The present study focuses on the investigation of the influence of various preparative parameters such as the ratio of internal water phase and oil phase, polymer concentration, solvent composition of organic phase and salt concentration of external water phase on the morphology and encapsulation efficiency of the microparticles. The microparticles fabricated at high volume ratios of internal water phase to oil phase and at high polymer concentrations showed a relatively high encapsulation efficiency and low porosity. When a dichloromethane/ethyl acetate mixture was used as solvent, both the encapsulation efficiency and drug loading of the microparticles decreased as the level of ethyl acetate increased. The addition of a salt (NaCl) to the external water phase significantly improved the encapsulation efficiency up to 40%, and the microparticles became more spherical with their size and porosity decreased.

• Food Science of Animal Resources
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• v.33 no.1
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• pp.67-74
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• 2013

The aims of this research were to produce oil-in-water ${\beta}$-lactoglobulin/alginate (${\beta}$-lg/Al) nanoemulsions loaded with coenzyme $Q_{10}$ and to investigate the combined effects of heating temperature and alginate concentration on the physicochemical properties and encapsulation efficiency of ${\beta}$-lg/Al nanoemulsions. In ${\beta}$-lg/Al nanoemulsions production, various heating temperatures (60, 65, and $70^{\circ}C$) and alginate concentrations (0, 0.01, 0.03, and 0.05%) were used. A transmission electron microscopy was used to observe morphologies of ${\beta}$-lg/Al nanoemulsions. Droplet size and zeta-potential values of ${\beta}$-lg/Al nanoemulsions and encapsulation efficiency of coenzyme $Q_{10}$ were determined by electrophoretic light scattering spectrophotometer and HPLC, respectively. The spherically shaped ${\beta}$-lg/Al nanoemulsions with the size of 169 to 220 nm were successfully formed. The heat treatments from 60 to $70^{\circ}C$ resulted in a significant (p<0.05) increase in droplet size, polydispersity, zeta-potential value of ${\beta}$-lg/Al nanoemulsions, and encapsulation efficiency of coenzyme $Q_{10}$. As alginate concentration was increased from 0 to 0.05%, there was an increase in the polydispersity index of ${\beta}$-lg/Al nanoemulsions and encapsulation efficiency of coenzyme $Q_{10}$. This study demonstrates that heating temperature and alginate concentration had a major impact on the size, polydispersity, zeta-potential value and encapsulation efficiency of coenzyme $Q_{10}$ in ${\beta}$-lg/Al nanoemulsions.

• 한국신재생에너지학회:학술대회논문집
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• 2011.05a
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• pp.130.1-130.1
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• 2011

Nowadays, the number of PV module corporation is increasing due to demand growth of silicon solar module. However almost study of module is research about increasing of efficiency for it. This study is evaluation and development for process of module using the silicone encapsulation material instead of existing EVA sheet. We are changed adding material ratio on silicone and thickness of silicone. So we get better efficiency than EVA sheet through the evaluation for silicone liquid and modulation. Also, we are test after establishing manufacture system being able to quicker than existing modules line. The result of EVA sheet is average 207.47W and silicone material is 211.32W so we think that silicone is better than EVA sheet.

• Archives of Pharmacal Research
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• v.10 no.2
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• pp.75-79
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• 1987

Liposomes were studied as a drug delivery system. Multilamellar vesicles, small unilamellar vesicles and large unilamellar vesicles containing cytarabine were prepared using egg yolk lecithin and cholesterol. Large unilamellar vesicles showed the highest encapsulation efficiency of all and their encapsulation efficiency increased as the buffer volume decreased. Cholesterol increased the stability of liposomal drug products as drug carriers and reduced the permeability of drug across the liposomal membrane. The release rate of cytarabine increased with incubation temperature and decreased with cholesterol incorporation in liposomal membrane. The release mechanism of cytarabine from large unilamellar vesicles in vitro was chiefly due to simple diffusion across the liposomal membrane rather than liposomal rupture.