• 대한화학회지
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• 제67권2호
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• pp.89-98
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• 2023

The cell membrane, also known as the biological membrane, surrounds every living cell. The main components of cell membranes are lipids and therefore called as lipid membranes. These membranes are mainly made up of a two-dimensional lipid bilayer along with integral and peripheral proteins. The complex nature of lipid membranes makes it difficult to study and hence artificial lipid membranes are prepared which mimic the original lipid membranes. These artificial lipid membranes are prepared from phospholipid vesicles (liposomes). The liposomes are formed when self-forming phospholipid bilayer comes in contact with water. Liposomes can be unilamellar or multilamellar vesicles which comprises of phospholipids that can be produced naturally or synthetically. The phospholipids are non-toxic, biodegradable and are readily produced on a large scale. These liposomes are mostly used in the drug delivery systems. This paper offers comprehensive literature with insights on developing basic understanding of lipid membranes from its structure, organization, and phase behavior to its potential use in biomedical applications. The progress in the field of artificial membrane models considering methods of preparation of liposomes for mimicking lipid membranes, interactions between the lipid membranes, and characterizing techniques such as UV-visible, FTIR, Calorimetry and X-ray diffraction are explained in a concise manner.

• 대한약리학회지
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• 제26권1호
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• pp.77-82
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• 1990

Dipalmitoyl phosphatidylcholine(DPPC)과 dipalmitoyl phosphatidic acid(DPPA) 리포좀내 이중층의 열적 상전이에 미치는 칼슘과 페노치아진 유도체의 영향을 시차 열량 분석계로 연구하였다. 인지질 이중층은 가열시 어느 특정온도에서 급격한 구조적 변화를 가져왔다. 이러한 온도에 의존한 변화는 순수 인지질의 경우 특이할 만큼 예민하였다. 순수 인지질에 페노치아진 유도체를 가하였을 때 순수 인지질의 상전이 온도보다 낮은 온도에서 일어 났으며 상전이 열그림을 넓적하게 만들었다. 칼슘 이온은 DPPC: DPPA(34: 66mol%)의 상전이 온도를 높였다. 그러나 위의 혼합 인지질에 페노치아진 유도체를 가하였을 때 $73^{\circ}C$에서의 작고 넓적한 곡선 부분이 사라졌다. 이러한 현상은 아마도 칼슘과 폐노치아진 유도체의 산성 인지질의 친수부분에서 상호 경쟁적 작용에 기인된 것으로 추정되어진다.

• 한국염색가공학회지
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• 제33권4호
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• pp.338-347
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• 2021

In the case of occlusive dressings currently used in dressings for burn treatment, it is impossible to confirm the replacement time, so replacement is delayed, resulting in additional infection. To solve this problem, liposomes capable of bacterial sensing were prepared using 5(6)-Carboxyfluorescein, Phosphatidylcholine, 1,2-Dipalmitoyl-sn-glycero-3-phosphocholine, Cholesterol, and 10,12-Tricosadiynoic acid. In this study, evaluation of changes in drug encapsulation rate in liposomes according to changes in three types of phosphatidylcholine phospholipids during liposome production, high-performance phosphatidylcholine phospholipids selected through vesicle size analysis, low and high temperature stability evaluation, bacterial sensitization ability evaluation, animals cell responses were assessed.

• Bulletin of the Korean Chemical Society
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• 제18권7호
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• pp.761-766
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• 1997

Phospholipase C from Clostridium perfringens is known to catalyze the hydrolysis of phospholipids in biological membranes. In this study, a simple and sensitive method for assaying phospholipase C was developed by using liposomes entrapping calcein as a fluorescent marker. Phospholipase C-induced lysis of liposomes was determined by measuring the fluorescence intensity of calcein released out from liposomes, Various liposomes with different compositions were prepared by reverse-phase evaporation method to investigate the effect of liposomal composition on the lytic activity of phospholipase C. The calcein-entrapping efficiency of liposomes was affected by the chain length of fatty acid in phosphatidylcholine constituting liposomes. The lytic activity of phospholipase C was the highest against liposomes prepared with eggPC. The lytic activity decreased with increasing chain length of fatty acid in phosphatidylcholine. Incorporation of cholesterol more than 20% into the liposomal bilayer inhibited the phospholipase C-induced lysis. The lysis of liposomes was more greatly increased by the addition of 10 mM of calcium. The lytic activity of phospholipase C was also affected by the surface charge of liposomes. Taken together, it was concluded that reverse-phase evaporation vesicles composed of dipalmitoylphosphatidylcholine and cholesterol in the molar ratio of 9 : 1 allowed to detect the lowest concentration of phospholipase C (0.10 μg/assay volume). This study suggested that the use of liposomes can provide a simple, sensitive and inexpensive method for assaying phospholipase C.

• 약학회지
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• 제38권2호
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• pp.131-139
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• 1994

Calcein-encapsulated small unilamellar vesicles of various lipid composition were prepared using the sonication technique, and their stabilities at $20^{\circ}C$ were examined by measuring calcein leakage from the liposomes. The fluidity of these liposomal bilayers was also investigated by measuring the fluorescence polarization of DPH labelled into the liposomes. The results showed that liposomes made of PC mixtures with different acyl chain length were very stable, which may be due to the formation of interdigitated bilayer structure. The addition of cholesterol further stabilized these PC liposomes. However, addition of cholesterol reduced the encapsulation efficiences of liposomes. The fluidity of the liposomes was significantly decreased by cholesterol in the liquid crystalline state, but not changed in the gel state. These results suggest that the enhanced stability of PC mixture liposomes may be ascribed to the formation of stable interdigitated bilayer structure. In membrane-mimetic and drug-delivery studies, vesicles made of mixtures of various phospholipids are recommended instead of addition of cholesterol to the phospholipid.

• 대한방사성의약품학회지
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• 제8권2호
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• pp.151-156
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• 2022

Liposomes are bilayered particles that are surrounded by an aqueous solvent with amphiphilic substances such as phospholipids. Liposomes have the potential to overcome the limitations of physiochemical properties of existing drugs, and are therefore widely used in research for the treatment of many diseases, especially cancer. Currently, there are many liposome manufacturing methods that use various lipids and amphiphiles. Among them, the thin film-hydration method is a traditional and very simple method to prepare liposomes by hydrating a dry lipid film in an aqueous solvent, which has been widely used in the laboratory until recently. Recently, approaches to new nuclear imaging agents and radiotherapy by loading radioactive isotopes inside liposomes have been actively studied. In this review, we would like to discuss considerations for preparing liposomes using the thin film-hydration method.

• 대한방사성의약품학회지
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• 제3권1호
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• pp.25-31
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• 2017

Liposomes are defined as spherical, self-closed structures formed by lipid bilayers containing aqueous phase. Most liposomes are composed of various amphipathic lipids such as phospholipids and cholesterol. We used amphipathic lipids (DPPC, DPPG) as liposome components and prepared around 100 nm liposomes by standard extrusion method. Nuclear/MR dual imaging agents based on liposome platform were prepared by adding radioactive $^{131}I$-HIB (hexadecyl-4-tributylstannylbenzoate) and Gd-DTPA into liposome bilayer and inside liposome, respectively. Gamma camera and MR imaging both showed signal increases in liver.

• Journal of Pharmaceutical Investigation
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• 제33권3호
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• pp.187-193
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• 2003

This study was aimed to formulate various phospholipid nanoparticles composed of different surfactants and to evaluate the deformability of the phospholipid vesicles as candidates of useful ultradeformable nanoparticles. In vitro deformability of the phospholipid nanoparticles was studied using an extruder under a certain pressure. The sizes of phospholipid nanoparticles, passed volumes, and concentrations of the phospholipids in suspensions before and after extrusion were measured. The deformability indexes were estimated by using passed volumes, sizes of phospholipid nanoparticles and concentrations of phospholipids. Conventional liposomes, placed under a certain pressure of an extruder, showed no passed volume indicating little deformability. Similar to conventional liposomes, phospholipid nanoparticles containing surfactants such as sodium taurocholate, Myrj 45, or Myrj 53 showed little deformability. In contrast, phospholipid nanoparticles composed of Tween 20, Triton X-100, or sodium deoxycholate showed higher deformability indexes than others. Taken together, the deformability of phospholpid nanoparticles could be significantly affected by the type of surfactants. Moreover, these results suggest that the deformability of phospholipid nanoparticles could be modulated by surfactants.

• 한국축산식품학회지
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• 제28권5호
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• pp.549-554
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• 2008

난황 유래의 인지질을 주원료로 리포좀을 제조하여 서로 다른 저장조건에서의 리포좀의 물리적인 안정성을 연구하였다. 리포좀 용액의 pH를 달리하여 저장한 후 리포좀 입자크기와 리포좀 용액의 제타전위와 형광도를 측정한 결과, 리포좀은 pH 1-2에서 입자크기의 증가를 나타내었고 pH 4 이하에서 제타전위의 절대값이 감소하였으며 리포좀의 내부에 포집한 수용성물질의 손실량 지표인 형광도의 측정치 또한 pH 2-4에서 급격하게 증가한 것으로 보아 산성의 저장조건에서는 리포좀이 불안정함을 추론할 수 있다. 저장 온도별 리포좀의 안정성 평가에서는 $4^{\circ}C$에서 저장하였을 때 10일째부터 입자의 크기 변화가 있었고 20, $35^{\circ}C$에서 저장할 경우, 저장기간 40일째 이후부터 입자의 크기변화가 있었다. 제타전위는 3가지 온도조건에서 동일하게 저장 말기에 측정값의 절대값이 미세하게 감소하는 경향을 보였다. 또한, $50^{\circ}C$에서 저장된 리포좀의 형광도 측정실험에서 포집된 SRB의 누출량이 급격히 증가하는 양상을 나타내었다. 따라서 pH 6 이하의 산성의 조건에서 리포좀은 불안정하며 $50^{\circ}C$와 같이 높은 온도에서 인지질로 구성된 리포좀의 안정성을 유지하기 어렵다는 것을 알 수 있었다. 본 연구의 결과는 난황 유래 인지질로 구성된 리포좀을 이용한 진단용 시약 개발 및 포집 특성 연구에 유용한 기초 자료로 활용될 수 있을 것이다.

• Toxicological Research
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• 제6권1호
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• pp.109-119
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• 1990

Ro09-0198, a cyclic peptide isolated from culture filtrates of Streptoverticillium griseoverticillatum, induced lysis of erythrocytes. Ro-09-0198-induced hemolysis was temperature-dependent and the sensitivity of hemolysis differed greatly among animal species. Preincubation of the peptide with phosphatidylethanolamine reduced the hemolytic activity, whereas other phospholipids present in erythrocytes in nature had no effect. A study of the structural requirements on phosphatidylethanolamine necessary for interaction with the peptide indicates that Ro09-0198 recognizes strictly a particular chemical structure of phosphatidylethanolamine: dialkylphosphoethanolamine as well as 1-acylglycerophosphoethanolamine showed the same inhibitory effct on hemolysis induced by Ro09-0198 as diacylphosphatidyl-ethanolamine, whereas phosphoethanolamine gave no inhibitory effect. Neither phosphatidyl-N-monomethylethanolamine nor alkylphosphopropanolamine had an inhibitory effect. Proton resonances of the peptide were observed in dimethyl sulfoxide solution in the presence of 1-dodecanoyl-sn-glycerophosphoethanolamine. This peptide caused permeability increase and aggregation of liposomes containing phosphatidylethanolamine. A glycerol backbone and a primary amino group of phosphatidylethanolamine are necessary for interaction with Ro09-0198 to cause membrane damage. Ro09-0198 induced a selective permeability change on liposomes. Glucose and umbelliferyl phosphate were effluxed significantly, but sucrose was only slightly permeable and inulin could not be released. Platelet aggregation and serotonin release simultaneously induced by Ro09-0198. Addition of peptide to rat platelet, loaded with the fluorescent $Ca^{++}$ chelator quin-2, caused immediate rise in cytosolic free $Ca^{++}$ to liposomal membrane containing phosphatidylethanolamine was observed dose dependently.