• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.16 no.2_3
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• pp.59-65
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• 2010

Starch was modified with epichlorohydrin(ECH) to improve the miscibility with LDPE and LLDPE. Native starch or epichlorohydrin treated starch was mixed with grycerol and LDPE/LLDPE resin using a kneader and extruded using a single screw extruder to make pallets. The pallets were compression-molded at 145 into composite boards to evaluate their color, oxygen permeation, mechanical and thermal properties, and degradability under UV irradiation. Sheets with epichlorohydrin treated starch generally showed higher L-value than that of native starch blend sheets. The hunter b-values in both native starch blends and epichlorohydrin treated starch blends increased with Increasing starch contents. Tensile strength and percent elongation of sheets decreased with increasing starch contents. Tensile strength and percent elongation of sheets decreased with increasing starch contents. The degradability of blends under UV radiation increased with increasing starch contents in both blend types. The results represents that crosslinking of starch with epichlorohydrin may be a good method to improve miscibility of starch with petroleum-based materials.

• Macromolecular Research
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• v.11 no.4
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• pp.207-223
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• 2003

For last five years, we are developing the novel local drug delivery devices using biodegradable polymers, especially polylactide (PLA) and poly(D,L-lactide-co-glycolide) (PLGA) due to its relatively good biocompatibility, easily controlled biodegradability, good processability and only FDA approved synthetic degradable polymers. The relationship between various kinds of drug [water soluble small molecule drugs: gentamicin sulfate (GS), fentanyl citrate (FC), BCNU, azidothymidine (AZT), pamidronate (ADP), $1,25(OH)_2$ vitamin $D_3$, water insoluble small molecule drugs: fentanyl, ipriflavone (IP) and nifedipine, and water soluble large peptide molecule drug: nerve growth factor (NGF), and Japanese encephalitis virus (JEV)], different types of geometrical devices [microspheres (MSs), microcapsule, nanoparticle, wafers, pellet, beads, multiple-layered beads, implants, fiber, scaffolds, and films], and pharmacological activity are proposed and discussed for the application of pharmaceutics and tissue engineering. Also, local drug delivery devices proposed in this work are introduced in view of preparation method, drug release behavior, biocompatibility, pharmacological effect, and animal studies. In conclusion, we can control the drug release profiles varying with the preparation, formulation and geometrical parameters. Moreover, any types of drug were successfully applicable to achieve linear sustained release from short period ($1{\sim}3$ days) to long period (over 2 months). It is very important to design a suitable formulation for the wanting period of bioactive molecules loaded in biodegradable polymers for the local delivery of drug. The drug release is affected by many factors such as hydrophilicity of drug, electric charge of drug, drug loading amount, polymer molecular weight, the monomer composition, the size of implants, the applied fabrication techniques, and so on. It is well known that the commercialization of new drug needs a lot of cost of money (average: over 10 million US dollar per one drug) and time (average: above 9 years) whereas the development of DDS and high effective generic drug might be need relatively low investment with a short time period. Also, one core technology of DDS can be applicable to many drugs for the market needs. From these reasons, the DDS research on potent generic drugs might be suitable for less risk and high return.

• Korean Journal of Veterinary Research
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• v.57 no.4
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• pp.215-222
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• 2017

Temporal and subcellular distributions of hyaluronic acid (HA) as a degradable nanoparticle (NP) in animals were investigated to determine if HA-NP could be utilized as an appropriate drug delivery system. After mice were intravenously injected with 5 mg/kg of Cy5.5-labeled HA-NP sized 350-400 nm or larger HA-polymers, the fluorescence intensity was measured in all homogenized organs from 0.5 h to 28 days. HA-NP was greatly detected in spleen, liver and kidney until day 28, while it was maintained at low levels in other organs. HA-polymer was observed at low levels in all organs. HA-NP quantities in spleen and liver were reduced until day 3, but increased sharply between days 3 and 7, then decreased again, while their HA-polymers were maintained at low levels until day 28. In kidneys, both HA-NP and HA-polymer showed high levels after 0.5 h of administration, but steadily decreased until day 28. According to ultrastructural analyses, HA-NP was engulfed in Kupffer cells of liver and macrophages of spleen and kidney at day 1 and was accumulated in the cytoplasm of kidney tubular cells at day 7. Overall, these findings suggest that HA-NP could be considered a desirable drug carrier in the liver, kidney, or spleen.

• Polymer(Korea)
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• v.25 no.4
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• pp.486-495
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• 2001

Degradable poly(butylene succinate) (PBS)/poly(TEX>${\varepsilon}$-caprolactone) (PCL) copolyesters were prepared by using transesterification between poly(butylene succinate) and poly(TEX>${\varepsilon}$-caprolactone). The thermal and mechanical properties of copolyesters were investigated using differential scanning calorimetry and tensile testing. Interchange reaction between PBS and PCL molecules could be identified from proton NMR spectra. The reduced viscosity of the PBS/PCL copolyesters increased with reaction time except for a series of PBS/PCL (50/50 wt%) copolyesters. For all the compositions, the melting point and crystallization temperature of high-$T_m$ component (PBS) decreased as reaction time increased. From the results of tensile testing, it was found that stress and strain at break of the PBS/PCL copolymers containing less than 40 wt% PCL improved as compared to those of pure PBS, but at 50 wt% PCL stress at break of PBS/PCL copolymers was lowered due to decrease of crystallinity. On the other hand, Young's moduli of all the copolyesters decreased with both reaction time and PCL content.

• KSBB Journal
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• v.21 no.4
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• pp.255-259
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• 2006

The biodegradable hyaluronic acid(HA) membranes cross-linked with lactide using the crosslinking agent, 1-ethyl-3(3-dimethyl aminopropyl) carbodiimide(EDC) were prepared as a potential biocompatible material for tissue engineering. HA membranes having different mechanical properties were synthesised by varying degree of the mole ratio of lactide to HA, EDC concentration, and crosslinking temperature. HA membranes were degradable in water solution and the degradation became slower with the increasing mole ratio of lactide to HA. HA membranes were sterilized using ethylene oxide gas and extracted with cell culture medium for 24 h at $37^{\circ}C$ and 200 rpm. Cytotoxicity of the extract was tested using NIH/3T3 mouse embryo fibroblast as a model cell. Growth inhibition was not observed in the extracts of HA membranes with the mole ratios of lactide to HA, 5 or 10, and 10% EDC concentration, however 11% of growth inhibition was observed in the extract with the mole ratio of 13. Growth inhibition was not observed in the extracts of HA membranes prepared with 5% EDC or 10% EDC and the mole ratio of lactide to HA, 10, however 12% of growth inhibition was observed in the extract with 20% EDC. Cytotoxicity was not observed in the extracts of HA membranes prepared at varying crosslinking temperatures, $15^{\circ}C,\;25^{\circ}C,\;and\;28^{\circ}C$ with the mole ratio of lactide to HA, 10 and 10% EDC.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.30 no.3 s.47
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• pp.295-305
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• 2004

Colloid and surface chemistry have been focused on surface area and surface energy. Local surface properties such as surface density, interaction, molecular orientation and reactivity have been one of interesting subjects. Systems of such surface energy being important would be listed as association colloid, emulsion, particle dispersion, foam, and 2-D surface and film. Such nanoparticle systems would be applied to drug delivery systems and functional cosmetics with biocompatible and degradable materials, while nanoparticles having its size of several nm to micron, and wide surface area, have been accepted as a possible drug carrier because their preparation, characteristics and drug loading have been inves-tigated. The biocompatible carriers were also used for the solubilization of insoluble drugs, the enhancement of skin absorption, the block out of UV radiation, the chemical stabilization and controlled release. Nano/micro emulstion system is classified into nano/microsphere, nano/microcapsule, nano/microemulsion, polymeric micelle, liposome according to its prep-aration method and size. Specially, the preparation method and industrial applications have been introduced for polymeric micelles self-assembled in aqueous solution, nano/microapsules controlling the concentration and activity of high concen-tration and activity materials, and monolayer or multilayer liposomes carrying bioactive ingredients.