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81.
Egg phosphatidylcholine (PC) liposomes bearing pH-sensitive polymers and dioleoylphosphatidylethanolamine (DOPE) liposomes
including the same polymers were prepared by a sonication method. As pH-sensitive polymers, copolymers of N-isopropylacrylamide, methacrylic acid, and octadecylacrylate were used. The liposomes were stable in neutral pH ranges in
terms of release. But the release became marked at pH 5.5, and it was accelerated as pH further decreased. For example, the
degree of release from egg PC liposomes (polymer/lipid ratio is 3:10, w/w) for 120 s increased from 2% to 63% as pH decreased from 7.5 to 4.5. Under the same condition, the degree of release from
DOPE liposomes increased from 4% to 80%. These results indicate that DOPE liposome is more pH-sensitive than egg PC liposome. 相似文献
82.
83.
Leonard M.C. Sagis 《Physica A》2009,388(13):2579-2587
The deformation relaxation behavior of two types of vesicles, liposomes and polymersomes, was investigated using a general nonequilibrium thermodynamics theory based on the interfacial transport phenomena (ITP) formalism. Liposomes and polymersomes are limiting cases of this theory with respect to rheological behavior of the interfaces. They represent respectively viscous, and viscoelastic surface behavior. We have determined the longest relaxation time for a small perturbation of the interfaces for both these limiting cases. Parameter maps were calculated which can be used to determine when surface tension, bending rigidity, spontaneous curvature, interfacial permeability, or surface rheology dominate the response of the vesicles. In these systems up to nine different scaling regimes were identified for the relaxation time of a deformation with droplet size, with scaling exponent n ranging from 0 to 4. 相似文献
84.
以1,2-二硬脂酸甘油酯为原料,与三氯氧磷及乙醇胺反应合成1,2-二硬脂酰甘油磷酰乙醇胺(DSPE);再以聚乙二醇2000 (PEG2000)为原料,通过磺酰化、叠氮化反应合成叠氮基聚乙二醇2000(N_3-PEG2000); DSPE与N_3-PEG2000在N,N-羰基二咪唑(CDI)作用下生成叠氮基聚乙二醇2000-1,2-二硬脂酰甘油磷酰乙醇胺(N_3-PEG2000-DSPE);最后通过催化氢化制备氨基聚乙二醇2000-1,2-二硬脂酰甘油磷酰乙醇胺(NH_2-PEG2000-DSPE),其结构经过IR、MS及~1H NMR等确证。 相似文献
85.
Studies were performed to investigate the effects upon the relaxation times of mouse organs of intravenously administered Mn-DTPA entrapped in multilamellar liposomes, Mn-DTPA, 0.9% NaCl entrapped in liposomes, 0.9% NaCl. Manganese concentrations in injectates and tissues were assessed with 54Mn and atomic absorption. T1 and T2 of freshly excised tissues were measured in an NMR spectrometer at 20 MHz and 37% C with IR and CPMG sequences. Entrapment of Mn-DTPA in liposomes increased 54Mn accumulation in liver by 207% and in spleen 1208% and reduced 54Mn in heart by 20% and in kidney by 24% relative to free Mn-DTPA. Statistically significant increases in relaxation rates were produced. However, the increase in relaxation rate per unit concentration of Mn in tissue is reduced by 31% in liver and 62% in spleen when Mn is delivered inside liposomes. These observations have implications for the design of NMR contrast agents. 相似文献
86.
Liposomes can be effectively deposited on the inner surface of a capillary wall by flushing the electrophoretic system with a liposome suspension followed by air-drying of the capillary and removal of the excess of loosely bound liposomes by a 0.1 M NaOH wash. It was demonstrated that capillaries prepared in this way could be used for studies of analyte (drug)–liposome binding. The results were expressed as free binding energy changes [Δ(ΔG0)] relatively to an arbitrarily selected standard (acetylsalicylic acid). The results were compared to [Δ(ΔG0)] changes obtained from binding studies effected by capillary electrophoresis using a stable liposome plug in a capillary with minimized endoosmotic flow. Good agreement of data reported in the literature (without correction for the residual endoosmotic flow), our previous data obtained in a similar way (however, after the correction for the residual endoosmotic flow) and data obtained by the immobilized liposome affinity electrochromatography reported in this communication was achieved. 相似文献
87.
E. Urbn A. Bta E. Klumppand . Csiszr 《Colloids and surfaces. A, Physicochemical and engineering aspects》2003,230(1-3):201-206
The effect of 2,4-dichlorophenol (DCP) on the phosphatidylethanolamine (
--dipalmitoyl-phosphatidylethanolamine (DPPE))/water liposomes was studied in the temperature domains of the gel and liquid crystalline phases at the DCP/DPPE molar ratios of 10−1 and 10−3 by using differential scanning calorimetry (DSC) as well as small and wide angle X-ray scattering (SAXS and WAXS). Different character of the transitions between the gel and the liquid crystalline phases was observed in the lipid/water and by DCP-doped systems. The different DCP concentrations caused similar effects in the change of the layer arrangements of the gel phase, while the perturbation of the subcells of this phase was different. In the liquid crystalline phase, the DCP molecules did not affect the layer structure significantly. The calorimetrical behaviour of the systems were rather correlated to the changes of the subcells than to the layer arrangements. 相似文献
88.
Manconi M Isola R Falchi AM Sinico C Fadda AM 《Colloids and surfaces. B, Biointerfaces》2007,57(2):143-151
In order to study mechanisms involved in liposome–cell interaction, this work attempted to assess the influence of vesicle composition on the delivery of liposomal content to Hela cells. In particular, to evaluate pH-sensitive properties and cell interaction of the prepared liposomes, the lipid formulations contained cholesterol (Chol) and they were varied by using phosphatidylcholines with different purity degree: soy lecithin (SL; 80% phosphatidylcholine), a commercial mixture of soy phosphatidylcholine (P90; 90% phosphatidylcholine) or dipalmitoylphosphatidylcholine (DPPC; 99% of purity). A second series of liposomes also contained stearylamine (SA). Dehydration-rehydration vesicles (DRV) were prepared and then sonicated to decrease vesicle size. Vesicle–cell interactions and liposomal uptake were examined by fluorescence microscopy using carboxyfluorescein (CF) and phosphatidylethanolamine-dioleoyl-sulforhodamine B (Rho-PE) as fluorescent markers. Fluorescence dequenching assay was used to study the influence of pH on CF release from the liposomal formulations. Liposome adhesion on the cell surface and internalization were strongly dependent on vesicle bilayer composition. SA vesicles were not endocytosed. DPPC/Chol liposomes were endocytosed but did not release their fluorescent content into the cytosol. SL/Chol and P90/Chol formulations displayed a diffuse cytoplasmic fluorescence of liposomal marker. 相似文献
89.
Ran Wang Yingjie Yu Dr. Meiyu Gai Dr. Ana Mateos-Maroto Dr. Svenja Morsbach Xiang Xia Maomao He Prof. Jiangli Fan Prof. Xiaojun Peng Prof. Katharina Landfester Prof. Shuai Jiang Prof. Wen Sun 《Angewandte Chemie (International ed. in English)》2023,62(44):e202308761
Enzymatic reactions can consume endogenous nutrients of tumors and produce cytotoxic species and are therefore promising tools for treating malignant tumors. Inspired by nature where enzymes are compartmentalized in membranes to achieve high reaction efficiency and separate biological processes with the environment, we develop liposomal nanoreactors that can perform enzymatic cascade reactions in the aqueous nanoconfinement of liposomes. The nanoreactors effectively inhibited tumor growth in vivo by consuming tumor nutrients (glucose and oxygen) and producing highly cytotoxic hydroxyl radicals (⋅OH). Co-compartmentalization of glucose oxidase (GOx) and horseradish peroxidase (HRP) in liposomes could increase local concentration of the intermediate product hydrogen peroxide (H2O2) as well as the acidity due to the generation of gluconic acid by GOx. Both H2O2 and acidity accelerate the second-step reaction by HRP, hence improving the overall efficiency of the cascade reaction. The biomimetic compartmentalization of enzymatic tandem reactions in biocompatible liposomes provides a promising direction for developing catalytic nanomedicines in antitumor therapy. 相似文献
90.
We review the currently available material on the morphology and dynamics of phospholipids assembled into liposomes. Key information obtained from neutron scattering, nuclear magnetic resonance (NMR), and other techniques plays a crucial role in understanding the vital role of lipids in sustaining life in living organisms. We concentrate on the dynamics in the biologically important fluid phase in the time range from picoseconds to seconds, which includes a discussion of the center of mass diffusion of liposomes, membrane fluctuations; and lateral, rotational, and flip-flop motions of the lipids. We emphasize on the sensitivity of the dynamics on interactions with a variety of biologically relevant molecules such as cholesterol. By a comparison of data from literature, we witness a good agreement of the results from different techniques and studies. 相似文献