• Archives of Pharmacal Research
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• v.10 no.2
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• pp.94-99
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• 1987

By using the former equation (8), we modified the equation which can show the dissimilar osmotic behavior of liposome with composition change. The slope of the new equation was presented as the ratio of osmotically active volume (V$_{act}$= ) to the total volume (V$_{totel}$= $_{acl}$+ V$_{dead}$ ; V$_{dead}$ is osmotically inactive volume) of loposomes, we defined is as a Z-value, which can elucidate the dissimilarity of the osmotic activity of multilamellar liposomes with the change of phospholipid composition and the differences of physicochemical properties of liposomes. Z-value was applied for studying the physico-chemical properties of liposomal membrane. The factor that affects on the Z-value was not the lipid concentration of liposome stock dispersion but the lipid composition of liposomal membrane. As the content of dicetylphosphate, the negative charged phospholipid, was increased, the osmotic activity, represented by Z-value, of multilamellar liposome was decreased. Using the hypertonic conditions (shrinking region), Z-value steadily increased and reached a maximum at 10 mole percent cholesterol with increasing the cholesterol content.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.21 no.1
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• pp.38-52
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• 1995

The liposomes have been developed in many drugs and cosmetics fields. In this context, it should be mentioned that MLV liposomes can be prepared standing with the main compounds of the intercellular lipids, cholesterol, palmitic acid, cholesteryl ester and lecithin, by swelling reaction. We report properties of the formation of MLV liposomes with use of the lipid base and Microfluidizer. MLV liposomes formed as multilamellar vesicles(MLV). The effect of the gelation of MLV liposomes have been on swelling reaction which have been mixed lipid with polyol and water phase at high temperature(90$\pm$5$^{\circ}C$). MLV liposomes have been prepared in incorporating alpha hydroxy acid ligrediens. Optimum condition of MLV liposomes were passed three times in the microfluidizer, particle size of the vesicles should be within 150-350nm and those confirmed by freeze-fracture electron microscopy.

• Proceedings of the Korean Society of Applied Pharmacology
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• 1996.04a
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• pp.286-286
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• 1996

In order to elucidate the mechanism of action of transdermal absorption-enhancing compounds, i.e., pyrrolidone derivatives (2-pyrrolidone, 1-methyl-2-pyrrolidone, 1-ethyl-2-pyrrolidone, 1,5-dimethyl-pyrrolidone and 5-methyl-2-pyrrolidone), multilamellar liposome was prepared from the simulated stratum corneum lipid and employed as a model system for the barrier function of the stratum corneum. The liposomal membrane of the stratum corneum lipid liposome (SCLL) behaves as an osmometer and has an excellent barrier function. In addition, its phase transition temperatures are similar to those of human stratum corneum intercellular lipid region. Therefore, SCLL seems to be a useful skin model. To estimate the barrier function of SCLL, the osmotic behavior of SCLL was measured in the presence of pyrrolidone derivatives and the effect on the phase transition temperature of SCLL was also investigated using differential calorimetry. Above a certain concentration (MLAC), enhances perturb the barrier function of the liposome. The relationship between MLACs and the partition coefficient of the pyrrolidone derivatives was observed; the greater the partition coefficients, the smaller the MLAC. This suggests that the more hydrophobic enhancers penetrate into the lipid layer more easily and reduce the barrier function of membrane more effectively. The results of differential scanning thermograms of the SCLL suggest that the pyrrolidone derivatives had incorporated into the lipid layer in the liposome and increased the fluidity of the lipid layer in the liposome. Such activity might have some correlation with the transdermal absorption-enhancing activity these compounds.

• Journal of Pharmaceutical Investigation
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• v.25 no.3
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• pp.249-264
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• 1995

Although liposome has many advantages as a pharmaceutical dosage form, its application in the industrial field has been limited because of some problems such as preparation method, reproducibility, scale-up, stability and sterilization etc. Liposomes prepared by microemulsification method had defined size, narrow size distribution, reproducibility and high entrapment efficiency. For enhancing the stability, the dry form of liposome was recommended. These types of liposome are proliposome and freeze-dried liposome. The liposome must have some properties for preparing of freeze-dried liposome; small size $(50{\sim}200\;nm)$, narrow size distribution and cryoprotectant. In this experiment, the liposomes containing 5-Fluorouracil(5-FU) and its prodrug(pentyl-5-FU-1-acetate; PFA, hexyl-5-FU-1-acetate; HFA) were made with soybean phosphatidylcholine, cholesterol, stearylamine(SA) and dicetyl phosphate(DCP) employing hydration method or microemulsification method using $Microfluidizer^{TM}$. Both or liposome types were MLV and MEL. After preparation, freeze drying and rehydration were performed. In the process of freezing, trehalose(Tr) was added as a cryoprotectant. Their evaluation methods were as follows; entrapment efficiency, mean particle size and size distribution, dissolution test, retain of entrapment efficiency and turbidity after freeze-drying. The results are summarized as belows. The entrapment efficiency of 5-FU was dependent on total lipid concentration and cholesterol content but that of PFA and HFA was decreased when cholesterol was added. When DCP and SA were added, entrapment efficiency was decreased. As the partition coefficient of drug was increased, entrapment efficiency was increased. Under the same condition, entrapment efficiency of MEL is similar to that of MLV. The mean particle size and size distribution of MEL were smaller than those of MLV. Dissolution rates of drug from both liposome types were comparatively similar. Dissolution rates of drugs with serum and liver homogenate were faster than without these material. After preparation of liposome, free drug was removed efficiency by Dowex 50W-X4. When liposome was freeze-dried and then rehydrated in the presence of Tr, characteristics of liposome were maintained well in MEL than MLV. Tr Was used successfully as a cryoprotectant in the process of freeze drying and the optimal ratio of Tr:Lipid was 4:1(g/g).

• Proceedings of the Korean Society of Applied Pharmacology
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• 1996.04a
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• pp.283-283
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• 1996

The hydrolyzed-lactose milk for the lactase-deficient subject is sweeter than whole milk, and some subjects dislike its taste. To overcome this shortcoming the dried liposomes containing ${\beta}$-galactosidase to digest lactose in milk after drinking were prepared and examined the possible application of this dried liposomes to the lactase-deficient subjects. To improve the stability of conventional liposome suspension, the dried liposomes in the presence of trehalose were prepared by the dehydration-rehydration vesicles method. Small unilamellar vesicles, prepared with egg phosphatidyl cholesterol, and cholesterol, were mixed with ${\beta}$-galactosidase solution and then ;up[jo;ozed. The freeze-dried liposome was rehydrated and centrifuged. The resultant multilamellar vesicles were mixed with trehalose(4g/g lipid) and then lyophilized to produce final dried liposome. Trehalose increased the entrapping efficiency of liposomes by 3 fo1d compared to the liposomes without trehalose (13% vs. 46%).

• The Korean Journal of Nuclear Medicine
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• v.24 no.2
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• pp.317-324
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• 1990

Liposome was labelled with $^{99m}Tc$ after negative charged liposome was formed with combination of a few lipid components. $^{99m}Tc$ liposome was injected through the tail vein of C3H mice bearing fibrosarcoma and biodistribution of $^{99m}Tc$ liposome was evaluated. The results were as follows: 1) We confirmed formation of liposome which was small unillamellar and multilamellar vesicles. 2) In this experiment the optimal concentration of $SnCl_2$ was $156{\mu}g/ml$ to label liposome with $^{99m}Tc$ and labelling efficiency was 95%. 3) The labelled liposome was stable when it was incubated with human serum for 24 hours. Mean labelling efficiency was 94% at 24 hour. 4) The main uptake sites of Tc-99m liposome were liver and spleen. It showed significantly higher uptake than $^{99m}Tc$ HSA (p < 0.001). 5) $^{99m}Tc$ liposome uptake in tumor tissue was not significantly higher than $^{99m}Tc$ HSA uptake. In conclusion, $^{99m}Tc$ liposome disclosed high labelling efficiency and was highly stable. Liver and spleen were main uptake sites of $^{99m}Tc$ liposome. The uptake mechanism of $^{99m}Tc$ liposome also seemed to be different from that of $^{99m}Tc$ HSA. We conclude that $^{99m}Tc$ liposome would be a promising agents for the imaging of some tumor.

• Food Science and Biotechnology
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• v.14 no.5
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• pp.604-607
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• 2005

In this study, the effect of ${\beta}$-sitosterol (SS) in the liposome bilayer on the stability of incorporated retinol was evaluated. Retinol was incorporated into liposomes consisting of various ratios of soybean phoaphatidylcholine (PC) to SS, while liposomes were prepared as multilamellar vesicles by the dehydration/rehydration method. Retinol was readily incorporated into liposomes with various SS contents, with incorporation efficiencies higher than 98% for all conditions. The incorporation efficiency of retinol increased slightly as the SS content in liposomes increased. Its average particle size also increased as the SS content increased. Mean particle size at PC to SS ratios of 100:0, 90:10, 80:20, 70:30, 60:40, and 50:50 were 12.16, 17.57, 35.00, 40.62, 83.45, and $88.94\;{\mu}m$, respectively. Liposomal retinol degradation in aqueous solution was measured with respect to SS content at various periods of time at four different temperatures of 4, 25, 37, and $50^{\circ}C$, and the stability of the incorporated retinol enhanced as the SS content increased. At $4^{\circ}C$, for example, retinol in the liposomes of 50:50 (PC:SS) remained at 84.42% after storage for 10 days, while in 100:0 (PC/SS) it remained at 42.62%. These results indicate that SS content in liposomes played an important role in the incorporation efficiency of retinol and its stability.

• Korean Journal of Food Science and Technology
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• v.28 no.3
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• pp.399-404
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• 1996

Encapsulation of lysozyme using lecithin vesicles and its stimilated release properties were studied. Lecithin vesicles were prepared by the dehydration-rehydration (DR)method. The highest encapsulation efficiency (EE) value of 80.1% was obtained by sonicating the multilamellar vesicles (MLVs) at 100 KHz for 120 min in bath sonicator. The value of entrapment progressively increased with the concentration of lysozyme, while the EE value decreased with the increase of enzyme concentration up to 50mg per 100mg per 100mg of lecithin, and then became nearly constant. At the pH of 5.9, only a small amount of lysozyme was released from DR vesicles during incubation at $37^{\circ}C$ As the pH decreased to 3.0, lysozyme was released more rapidly. Lysozyme release was accelerated for 24h and reached a plateau after 72h incubation with 1% Tween 80, $Ca^{2+}$ gave a pulse-like-release in the first hour, which was followed by a slow release.

• Archives of Pharmacal Research
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• v.9 no.3
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• pp.119-125
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• 1986

Digitonin is a strong hemolysin and glycyrrhizin has protective activity against the deterring effect of other hemolytic saponins. The interaction of these saponins with liposomes was studied as a function of cholesterol in membrane. In the case of multilamellar vesicles, which act as ideal osmometers, digitonin distrupted the barrier function of liposomes composed of phosphatidyl choline, dicetyl phosphate and cholesterol, however, did not influence on cholesterol-lacking liposomes. Glycyrrhizin had similar effect on liposomes irrespective of cholesterol in membrane. In the test with large unilamellar vesicles, digitonin increased the lysis with increasing cholesterol content in membrane, but glycyrrhizin showed no detectable change in cholesterol-containing liposomes. These results suggest that incorporation of cholesterol into liposomes increases the susceptibility to digitonin, resulting in lysis of liposomes, and that the inhibitory effect of glycyrrhizin against other hemolytic saponins in cholesterol-independent.

• Preventive Nutrition and Food Science
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• v.5 no.3
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• pp.177-178
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• 2000

Chemical and photochemical precesses during food storage an preparation rapidly degrade $\beta$-carotene, the most active form of carotenoids. We investigated the possibility of liposomes as tool to preserve $\beta$-carotene. Liposomes with $\beta$-carotene were prepared as multilamellar vesicles by using soybean phosphatidylcholine, in terms of the ratio of $\beta$-carotene to phospholipid and pH. Incorporated efficiency was 99.7% at 1:0.05 of phospholipid : $\beta$-carotene and at pH 9.0. As the concentration of $\beta$-carotene increased, the incorporated efficiency increased progressively. pH did not affect the incorporation efficiency greatly.