• Journal of the Korean Chemical Society
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• v.51 no.1
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• pp.43-50
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• 2007

Liposomes having particle size from several tens to hundreds nanometers are efficient carriers for injectable drug delivery. Enhancement of liposome stability in bloodstream has been studied because of its relatively short circulation time and fast clearance from human body by reticuloendothelial system (RES) in blood vessel. In this study, new disaccharide-1,2-distearoyl-sn-glycero-3-phosphoethanolamine (DSPE) derivatives in which lactose or sucrose as the disaccharide molecule was conjugated covalently to DSPE were synthesized. Liposomes of which surface had disaccharide molecules were prepared by incorporating the disaccharide-DSPE into liposomes as one of their lipid components. Particle size of the prepared liposomes was approximately 100 nm. The liposomes of which surface were modified with the disaccharide-DSPE showed -25 mV of zeta potential value due to the presence of hydroxyl groups on their surface, while the unmodified control liposomes showed -10 mV of zeta potential value. Loading efficiency of model drug, doxorubicin, into liposomes was about 90%. Stability of the disaccharide-modified liposomes in vitro was evaluated by monitoring the amount of protein adsorption and particle size of the liposomes in serum. Disaccharide-modified liposomes were more stable in serum than unmodified control liposomes or polyethyleneglycol (PEG)-modified liposomes due to less adsorption of serum protein and hence less increase of their particle size. The liposomes of which surface was modified with disaccharide-DSPE conjugate can be used as long-circulating carriers for drugs having high toxicity or short half-life time due to their enhanced stability in blood circulatory system.

• Journal of the Korean Chemical Society
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• v.58 no.6
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• pp.575-579
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• 2014

Development of liposomes has been actively studied for effective delivery of drug at tumor site. However, despite their preferential accumulation at tumor site, the therapeutic efficacy of such liposomal drug has been limited because of low drug release. Therefore, we developed a temperature-sensitive liposome (TSL), which can be made to maximize release of drug by external stimulation such as ultrasound. Doxorubicin (DOX) as a model drug was encapsulated into TSL by a pH gradient method. The particle size of the TSL was $142.0{\pm}6.24nm$. Surface charge was $-10.55{\pm}1.12mV$. Release of drug from TSLs was up to 80% within 15 min at over $42^{\circ}C$ measured by fluorescence intensity. Cytotoxicity of released DOX from TSLs with ultrasound was highly increased compared to TSLs without ultrasound. Taken together, we demonstrate that temperature sensitive drug release from TSLs with ultrasound, which may be useful for cancer therapy to increase drug concentration at tumor site by external stimulation.

• KSBB Journal
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• v.18 no.3
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• pp.229-233
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• 2003

Antioxidant effect of reconstituted liposome was studied for application to food and cosmetic industry. Vitamin-C/alginate alginate gel-entrapped DHA-PC liposome (AVDL) was prepared and studied with respect to morphology (TEM), loading efficiency (TLC) and antioxidant effect (TBARS assay). AVDL has spherical structure and 80 ∼ 250 ㎚ size. As DHA content increased, DHA and PC loading efficiency and antioxidant effect was increased. At addition of 0.2 % vitamin C in AVDL, DHA auto-oxidation was minimized and sustained about 3 days.

• Journal of the Korean Chemical Society
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• v.57 no.5
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• pp.634-639
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• 2013

The use of medical imaging has been increased for diagnosis of cancer or vessel disease. Among the medical imaging, computed tomography (CT) is one of the popular methods, however, which should need administration of contrast medium. Therefore, we developed gold coated liposomes (GCL) as a contrast medium. To coat gold on the liposomal surface, positive charged liposomes was prepared and then negative $Au^-$ can coat on the liposomal surface by electronic interaction. The size of GCL was $154.8{\pm}9.2$ nm and surface charge was $27{\pm}3.2$ mV, respectively. The morphology of GCL was confirmed by electron microscopy (SEM) and transmission electron microscopy (TEM). The coating efficiency of gold was 18%. Chemical procedure for gold coating on liposomal surface was not toxic for cell cytotoxicity by MTT assay. Finally, we demonstrated attractive CT image for GCL. Taken together, the GCL would be useful for various vessel related disease as a contrast medium.

• Korean Journal of Food Science and Technology
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• v.52 no.2
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• pp.200-203
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• 2020

The effect of stigmasterol (SS), a phytosterol, in the liposome bilayer on the stability of encapsulated ascorbic acid (ASA) was evaluated. Liposomes, consisting of phosphatidylcholine (PC) and SS, and ASA were encapsulated by the dehydration/rehydration method. The average particle size of the liposome increased with increasing SS content. SS significantly increased the stability of encapsulated ASA. For example, ASA remaining in the liposomes of 100:0, 90:10, and 70:30 (PC:SS, w/w) ratios was 34.12%, 49.88%, and 58.58%, respectively, after storage for 8 days at 4℃, while only 7.66% ASA remained in the buffer under the same conditions. These results indicated that SS in liposomes increased the stability of encapsulated ASA.

• Applied Biological Chemistry
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• v.42 no.3
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• pp.205-209
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• 1999

Cholesterol plays an important role in various physiological responses and membrane stability. To investigate the effect of cholesterol in liposome on the stability of encapsulated ascorbic acid, the physico-chemical experiments using various amounts of cholesterol-containing liposomes were performed. The encapsulation efficiency of ascorbic acid was decreased with increasing cholesterol content in liposome, whereas size of liposome was increased. Furthermore, the stability of encapsulated ascorbic acid was increased with increasing the content of cholesterol. The stability was not affected by pH. Encapsulated ascorbic acid in liposome stored at $37^{\circ}C$ was rapidly oxidized compared to those stored at $4^{\circ}C$. These results suggest that cholesterol in liposome affects largely to the stability of encapsulated ascorbic acid.

• Korean Journal of Food Science and Technology
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• v.31 no.2
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• pp.280-284
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• 1999

To overcome unstability of ascorbic acid, liposome was used to encapsulate it. Ascorbic acid was encapsulated with 46.8% efficiency inside soybean phosphatidyl choline liposomes by the dehydration-rehydration method. Stability of encapsulated ascorbic acid in liposome was enhanced compared to that in free aqueous solution. For example, most of ascorbic acid in acetate buffer (pH 5.0) was oxidized after 7 days, however, that in liposome was remained as reduced form with 22.8% after 40 days at same conditions. These results mean that encapsulation of ascorbic acid in liposome could provide protection tool for improvement in shelf life.

• Journal of the Korean Chemical Society
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• v.49 no.2
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• pp.189-195
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• 2005

• Journal of the Korean Chemical Society
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• v.49 no.6
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• pp.546-553
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• 2005

• Journal of the Korean Chemical Society
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• v.43 no.2
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• pp.193-198
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• 1999

The transfection efficiency of plasmid DNA was inspected using multi-cationic polymer, 5, 10, 25 and 50KD polyethylenimine (PEI). The optimal neutralization ratio of PEI/DNA complexes by agarose assay was 1.5-2.0 (nmol/nmol) without much difference in molecular weight of PEI.In vitro transfection assay, most of PEI-mediated plasmid delivery was better compared to the naked DNA. Especially, 25KD PEI at optimal condition gave higher transfection rather than the standard assay of DEAE-dextran or Lipofectin. To enhance the cell targeting delivery, the liposome formulations were introduced using phospholipids. As a result, PC/PE liposomes increased 2-2.5 times of the transfection efficiency of PEI single or PC/PE single delivery, but not the case of 25KD PEI. Moreover, the DOTAP/PE-introduced PEI delivery reduced the transfection of DOTAP/PE single delivery. All these results proved that the PEI can be used not only good transfectants and but also good DNA condensing agents in neutral/anionic liposome for cell targeting delivery.