• KSBB Journal
• /
• 제10권2호
• /
• pp.204-211
• /
• 1995

인지질 그 자체만으로는 안정한 이중층 리포좀을 형성하지 못하는 불포화 PE(DOPE)에 palmitoyl가 가 결합된 항체(p-IgG)를 지질층에 삽입시켜 lmm t unoliposome을 제조하고 그 특성에 관하여 살펴 보 았다. 우선 안정된 리포좀을 제조하기 위해서 고려 해야할 인자들로 항체 가공방법, 지질과 항체와의 몰 비, 그리고 각종 첨가제들에 대한 최적 조건을 조 사하였다. 예를 들면 p-IgG와 lipid의 볼비를 $2.5{\times}10^{-4}$ 으로 했을 때 안정한 리포좀을 만들 수 있었으며, 첨가제로 들어가는 DOC의 경우 최종 농도가 O.09wt % 일 때 calcein의 포집률이 최대가 되었고 c calcein의 최종 pH는 8.5~9.5 정도에서 안정한 라포좀이 제조될 수 있었다. 다중 빛 단일클론의 항체 를 삽입한 리포좀을 표면항원을 가진 표적세포와 결합시켰을 때 리포좀이 와해되면셔 포집된 calcein이 방출되는 것으로 보아 삽입된 p-IgG가 PE 리포좀을 형성하는데 필수척임을 알 수 있었다. 또 같은 리포좀을 비특이적인 세포와 접촉시켰을 때에는 아무 런 변화를 보이지 않아 calcein 방출이 항원-항체 반응에 의한 것임을 알 수 있었고 이로부터 표적 민 감성 PE 리포좀이 만들어졌음을 확인하였다.

• Macromolecular Research
• /
• 제13권1호
• /
• pp.54-61
• /
• 2005

We prepared temperature-sensitive liposomes (TS-liposomes) modified with a thermo sensitive polymer, such as poly(N-isopropylacrylamide) (PNIPAAm), to increase the degree of drug release from liposomes at the hyperthermic temperature. A PNIPAAm hydrogel containing TS-Iiposomes was also prepared to obtain a hydrogel complex at body temperature. In addition, a depot system for local drug delivery using the polymer hydrogel was developed to enhance therapeutic efficacy and prevent severe side effects in the whole body. The PNIPAAm-mod­ified TS-liposome was fixed into the PNIPAAm hydrogel having a high temperature-sensitivity. The release behavior of calcein, a model drug, from TS-liposomes in the PNIPAAm hydrogel was then initiated by external hyperthermia; the results indicated that sustained release as a function of temperature and time was caused by the thermosensitivity of the liposome surface and diffusion of the drug into the PNIPAAm hydrogel. Our results indicated that TS-liposomes in a PNIPAAm hydrogel represented a plausible system for local drug delivery.

• Journal of Pharmaceutical Investigation
• /
• 제20권3호
• /
• pp.135-144
• /
• 1990

The effects of bile salts (BS) on the stability of dioleoylphosphatidylethanolamine (DOPE) liposomes were investigated, observing apparent absorbance of vacant liposomes and calcein release from entrapped liposomes. Unilamellar liposomes were prepared by using a small quantity of palmitoly-immunoglobulin G(IgG) ($2.5{\times}10^{-4}$ mo1/lipid mol) to stabilize the bilayer phase of the unsaturated DOPE which by itself does not form stable liposomes. The destabilization of PE immunoliposomes by papain, clearly demonstrates that the IgG is essential for stabilization of PE bilayer. Approximately 4% of the entrapped calcein was released from the PE liposomes after 1 hr from liposome formation. Calcein release and absorbance of liposomes depended on the BS/lipid ratio because of the solubilization of lipid molecule in bilayer and the formation of mixed micelles. At very low BS concentrations, the incorporation of BS induced BS/lipid aggregates in the outer vesicles monolayer, while high BS concentrations, mixed micelles were formed. Chelate and its conjugates as $3{\alpha},\;7{\alpha},\;12{\alpha}-trihydroxy$ BS induce the concentration of the $3{\alpha}$, $12{\alpha}-dihydroxy$ BS at half-maximal solubilization of immunoliposomes to approximately 2.5-, or 5-fold. Conjugation of BS with glycine or taurine slightly enhanced their capacities to perturb membranes.

• KSBB Journal
• /
• 제10권4호
• /
• pp.428-434
• /
• 1995

Target-sensitive(TG-S) liposomes, which have the antibodies coupled on the surface of liposome and can release their entrapped contents by the binding of antibodies with the specigic target cells, were prepared and employed to study the release of calcein and the selective delivery of an anticancer agent, doxorubicin(DOX). The monoclonal antibody, Y3, used for the preparation of the TG-S liposome was one against major histocompatibility complex class 1 of mouse(MHCI, H-2Kｂtype) and the target cells were EL-4 and RMA, which have the MHC1, H-2Kbtype on their membrane surfacem. The release of calcein from TG-S liposome occurred when the target cells were contacted with liposomes and it was proportionally increased with the rise of binding capacity of antibody coupled on the surface of liposome to the target cells. The experimental results of drug delivery were similar to the cases of calcein release. The viability of specific target cell, EL-4 with liposomal DOX was not so different from that with the free DOX, while for the non-specific target cell, Yacl(H-2Kf), the cell viability with Iiposomal DOX was much higher than that with free DOX. This shows the fact that the liposomal DOX can be efficiently delivered to the specific target cells, while it was not the case for the non-specific target cells. And the drug delivery was lnhibited when the free antibody of Y3 was added in the contact process between EL-4 and TG-S liposomes, which means the drug delivery occurred mainly by the destabilization of TG-S liposomes. From these results, we could conclude that the selective drug delivery to specific target cell using the TG-S liposome would be feasible.

• 공업화학
• /
• 제8권1호
• /
• pp.59-66
• /
• 1997

Di(10-hemisuccinyloxy)decyl muconate(DDM)와 di(6-hemisuccinyloxy)hexyl muconate(DHM)가 합성되었으며, 수용액에 분산되어 각각 $97^{\circ}C$과 $79^{\circ}C$에서 상전이를 나타내었다. 이들은 자체적으로, 또는 콜레스테롤이나 dioleoylphosphatidylethanolamine (DOPE)을 혼합하여도 리포좀을 형성하지 않았지만, phosphatidylcholine(PC)과 혼합되면 리포좀을 형성하였다. 리포좀막에서 DHM이 254nm의 자외선에 노출될 때 1,2-중합반응이 쉽게 진행되었다. DOPE/dioleoylphosphatidylcholine(DOPC)/DHM(3/3/1)으로 구성된 리포좀은 중성 pH에서는 안정하지만 약산성 pH에서는 불안정하여 pH 4.8과 5.8의 phosphate-buffered saline(PBS, $37^{\circ}C$)에서 30분과 50분 이내에 각각 봉입된 calcein의 방출이 완료되었다. calcein의 방출은 pH가 감소됨에 따라서 증가하며 pH 5.5와 5.0 근처에서는 각각 봉입 calcein의 50%와 100%가 방출되었다.

• 한국정보통신학회:학술대회논문집
• /
• 한국정보통신학회 2015년도 추계학술대회
• /
• pp.958-960
• /
• 2015

말기 암환자를 위해 시행되는 화학적 항암치료는 다양한 합성 운반체를 이용한 표적치료를 통해 그 효과와 안정성을 증가시킨다. 항암치료의 약물 운반체로 쓰이기 위해 다음과 같은 독특한 두 가지 특성을 만족시켜야 하는데, 이것은 약물유출의 사용자 중심 제어기능과 표적 고형암으로의 높은 전달성이다. 하지만 현재 임상에서 사용되는 합성 운반체는 다양한 부작용을 유발하여 항암치료의 효과를 억제하고 환자들의 신체적 정신적 고통을 증가시키고 있다. 따라서 본 논문에서는 생착성과 생분해능력을 가지고 있는 겸형적혈구에 활성화된 광감응제를 부착하고 형광물질을 주입하여, 지연적 용혈을 이용한 유출제어기능과 겸형적혈구의 표적기능을 일반 형광물질 주입결과와 비교하여 실험을 진행하였다. 이를 위하여 유전적으로 변이된 전임상 모델에서 생성된 겸형적혈구를 암세포가 자라는 설치류에 주입한 후, 일정 시간 간격으로 유출정도를 초분광이미징 시스템을 이용하여 모니터링 하였고, 그 결과 약물전달 운반체로서의 겸형적혈구의 역할 및 합성 운반체의 대체 가능성을 보이고자 한다.

• Journal of Pharmaceutical Investigation
• /
• 제22권2호
• /
• pp.115-124
• /
• 1992

The characteristics and stabilities of phosphatidylcholine liposomes covalently coupled with immunoglobulin fragments prepared by the REV method were investigated by the dynamic light scattering, absorbance and calcein release. Using a sulfhydryl-reactive phospholipid derivative of N-[4$({\rho}-maleimido-phenyl)$ butyl] phosphatidylethanolamine (MPB-PE), Fab' antibody fragments were covalently combined with preformed large unilamellar vesicles (LUV), Coupling ratio was $250\;{\mu}g$ of $Fab'/{\mu}mol$ of phospholipid in vesicles, From dynamic light scattering, it was found that the size of the vesicles increases as the ratio of cholesterol to lipid increases, but that apparently, the size of liposomes was not sensitive to the existence of Fab' fragments. Regardless of inserting Fab' fragments, the absorbance of liposomes decreased as the amounts of bile salt (BS) added. At very low BS concentrations, BS/lipid aggregates would be formed in the outer vesicles monolayer, while, at the high BS concentrations, mixed micelles would be preferred. The vesicles incorporated with Fab' fragments, however, are more resistant to the bile salts than the MPB-PE vesicle are. The absorbance of vacant liposomes and calcein release resulted in that the Fab' vesicles and MPB-PE vesicles by the REV method are very stable, but that those by the sonication method sufferred the significant change of turbidities.

• Bulletin of the Korean Chemical Society
• /
• 제19권6호
• /
• pp.645-649
• /
• 1998

In order to develop pH-sensitive liposomes that are stable in plasma, liposomes containing membrane-spanning bipolar amphiphiles as protonatable components were studied. Sonicated small unilamellar liposomes composed of dioleoylphosphatidylethanol amine (DOPE), dioleoylphosphatidylcholine (DOPC) and bis(6-hemisuccinyloxyhexyl) fumarate (BHF) in a 3 : 1 : 1 molar ratio are stable at neutral pH, but destabilized at weakly acidic pH with 50% leakage of entrapped materials at about pH 5.5. The liposomes are relatively stable in plasma such that only a few percent entrapped calcein was released in 50% plasma within 1.5 h incubation at 37 ℃, while about 10% entrapped calcein was released from sonicated liposomes composed of DOPE, DOPC, and oleic acid (OA) in a 3 : 1 : 1 molar ratio under the identical conditions. The aqueous contents mixing and lipid components mixing experiments suggest that the protonation of BHF may induce fusion between the liposomes, followed by the release of the entrapped materials.

• 공업화학
• /
• 제17권2호
• /
• pp.138-143
• /
• 2006

Ethosome은 에탄올에 용해된 레시틴을 친수성 용액으로 수화시켜 만들어지는 액정형 베시클이다. Ethosome을 약물전달체로 개발하기 위해서는 베시클의 높은 포집효율과 작은 입자크기가 필수적이기 때문에 ethosome의 포집효율과 입자크기에 영향을 주는 인자들에 대한 연구를 시도하였다. Calcein을 친수성 지표물질로 사용하여 ethosome을 만들고, 구성 성분비와 제조조건에 따른 ethosome의 특성의 변화를 관찰하였다. 에탄올과 calcein 용액의 첨가량 레시틴 중 포스파티딜콜린의 함량, 제조온도, 교반속도 및 PBS 첨가방법 등이 ethosome의 특성에 상당히 큰 영향을 미치는 것을 확인하였다. 초음파 처리를 한 경우에는 ethosome의 포집효율이 감소하는 결과가 나타났는데 이러한 결과는 강한 초음파 진동에 의해 베시클에 포집되었던 성분이 방출되었기 때문이다.

• BMB Reports
• /
• 제39권3호
• /
• pp.270-277
• /
• 2006

Helices 4 and 5 of the Bacillus thuringiensis Cry4Ba $\delta$-endotoxin have been shown to be important determinants for mosquito-larvicidal activity, likely being involved in membrane-pore formation. In this study, the Cry4Ba mutant protein containing an additional engineered tryptic cleavage site was used to produce the $\alpha4$-$\alpha5$ hairpin peptide by an efficient alternative strategy. Upon solubilization of toxin inclusions expressed in Escherichia coli and subsequent digestion with trypsin, the 130-kDa mutant protoxin was processed to protease-resistant fragments of ca. 47, 10 and 7 kDa. The 7-kDa fragment was identified as the $\alpha4$-loop-$\alpha5$ hairpin via N-terminal sequencing and mass spectrometry, and was successfully purified by size-exclusion FPLC and reversed-phase HPLC. Using circular dichroism spectroscopy, the 7-kDa peptide was found to exist predominantly as an $\alpha$-helical structure. Membrane perturbation studies by using fluorimetric calcein-release assays revealed that the 7-kDa helical hairpin is highly active against unilamellar liposomes compared with the 65-kDa activated full-length toxin. These results directly support the role of the $\alpha4$-loop-$\alpha5$ hairpin in membrane perturbation and pore formation of the full-length Cry4Ba toxin.