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At least 19 recordsLinked to original sources
PubMed2003

Hyaluronan is a key component in cryoprotection and formulation of targeted unilamellar liposomes.

Lyophilized unilamellar liposomes (ULV), the dosage form of choice for shelf-life, revert upon reconstitution to the larger multilamellar liposomes (MLV), which is detrimental to the many carrier-mediated therapies that require small particles. High doses of sugars such as trehalose, sucrose and others, included in the original formulations for cryoprotection, were shown to prevent the conversion to MLV. In this study we set out to test whether hyaluronan (HA), the surface-bound ligand in our previously developed targeted bioadhesive liposomes (BAL), can also act as a cryoprotectant. The studies included structural and physicochemical characterization of original and reconstituted hyaluronan-ULV (HA-ULV). For each HA-ULV, similar regular ULV (RL-ULV) served as controls. Four properties were tested: particle size, zeta potential, encapsulation efficiency and half-life of drug release (tau(1/2)), for three drugs-chloramphenicol (CAM), vinblastine (VIN) and mitomycin C (MMC). Encapsulation efficiencies of the original systems were quite alike for similar RL-ULV and HA-ULV ranging from 25% to 70%. All systems acted as sustained-release drug depots, tau(1/2) ranging from 1.3 to 5.3 days. Drug species and lipid composition were the major determinants of encapsulation and release magnitudes. By all tests, as anticipated, lyophilization generated significant changes in the reconstituted RL-ULV: 17-fold increase in diameter; tripling of zeta potential; 25-60% drop in encapsulation efficiencies; 25-30% decrease in tau(1/2). In contrast, the reconstituted HA-ULV retained the same dimensions, zeta potentials, encapsulation efficiencies and tau(1/2) of the original systems. These data clearly show HA to be a cryoprotectant, adding another clinically relevant advantage to HA-BAL. We propose that, like the sugars, HA cryoprotects by providing substitute structure-stabilizing H-bonds.

Chemistry, Pharmaceutical↗
PubMed1990

Interactions of serum proteins with small unilamellar liposomes composed of dioleoylphosphatidylethanolamine and oleic acid: high-density lipoprotein, apolipoprotein A1, and amphipathic peptides stabilize liposomes.

Small unilamellar liposomes composed to dioleoylphosphatidylethanolamine (DOPE) and oleic acid (OA) are stabilized by incubation with normal human serum or plasma [Liu, D., & Huang, L. (1989) Biochemistry 28, 7700-7707]. The present report describes a systematic study of interactions of purified serum proteins and lipoproteins with these liposomes. Albumin destabilized liposomes by extracting OA from the liposomes, whereas immunoglobulins and lipoproteins (HDL, LDL, and VLDL) had no effect. However, HDL and, to some extent, VLDL showed a rapid stabilization activity against the lytic effect of albumin. HDL added together with or shortly after the addition of albumin completely abolished the liposome leakage and aggregation effects induced by albumin. SDS-PAGE analysis of the HDL-stabilized liposomes revealed that apolipoprotein A1 was associated with liposomes. Purified apolipoprotein A1, but not a lipid mixture resembling the lipid composition of HDL, showed comparable liposome stabilization activity as HDL. Furthermore, synthetic peptides resembling the amphipathic helices found in apolipoprotein A1 also showed strong liposome stabilization activity. Peptides which were able to form amphipathic helixes of a wedge shape were more effective stabilizers than those which could not. These data indicate that HDL plays a major role in human serum or plasma for the liposome stabilization activity. HDL exerts its activity probably by the interactions of the amphipathic helices of apolipoprotein A1 with the hydrophobic voids found on the outer surface of the highly curved, small liposomes.

Apolipoprotein A-I↗
PubMed1999

Covalent immobilization of unilamellar liposomes in gel beads for chromatography.

For immobilized (proteo)liposome chromatography, unilamellar liposomes were covalently bound within gel beads that had been activated by CNBr, N-hydroxysuccinimide, tresyl, or chloroformate. Liposomes composed of phosphatidylcholine (PC) and 2 mol% of amino-containing lipid (phosphatidylethanolamine-caproylamine) were immobilized in the activated gels at 5-35 micromol lipid/ml gel and yields of 11-70%. The highest immobilized amount was found in chloroformate-activated TSK G6000PW gel, which contains large pore size (>100 nm). Liposomes composed of PC alone could also be attached to the chloroformate-activated gels at 33-42 micromol/ml gel and yields of 58-65%, probably by crosslinking of the phosphate moiety of phospholipid with the active group of the adsorbent. Liposomes prepared by various phospholipids with or without amino-containing lipids can generally be immobilized in the chloroformate-activated gels. The covalently bound liposomes were characterized by their high stability, unilamellarity, permeability of the membranes, and drug-membrane partition properties. A stable membrane phase was constructed for chromatographic experiments to be performed under extreme elution conditions.

Chromatography, Gel↗
PubMed1992

Formation of unilamellar liposomes from total polar lipid extracts of methanogens.

Unilamellar liposomes were formed by controlled detergent dialysis of mixed micelles consisting of acetone-insoluble total polar lipids extracted from various methanogens and the detergent n-octyl-beta-D-glucopyranoside. The final liposome populations were studied by dynamic light scattering and electron microscopy. Unilamellar liposomes with mean diameters smaller than 100 nm were obtained with lipid extracts of Methanococcus voltae, Methanosarcina mazei, Methanosaeta concilii, and Methanococcus jannaschii (grown at 50 degrees C), whereas larger (greater than 100-nm) unilamellar liposomes were obtained with lipid extracts of M. jannaschii grown at 65 degrees C. These liposomes were shown to be closed intact vesicles capable of retaining entrapped [14C]sucrose for extended periods of time. With the exception of Methanospirillum hungatei liposomes, all size distributions of the different liposome populations were fairly homogeneous.

Dialysis↗
PubMedDate not supplied

Pharmacokinetics of small unilamellar liposomes and incorporated lonazolac after i.m. administration.

The nonsteroidal anti-inflammatory drug lonazolac [3-(p-chlorophenyl)-1-phenylpyrazole-4]-acetic acid was incorporated into the bilayer of liposomes. The unilamellar and homogeneously sized liposomes with a diameter of 45 +/- 7 nm were prepared by controlled detergent dialysis. The maximal amount of lonazolac incorporation is 0.140 mg per mg egg phosphatidylcholine (egg PC). The liposomes were stable over a year. Pharmacokinetics of the 3H- and 14C-labelled liposomes and of the 14C-labelled lonazolac was investigated after i.v. and i.m. administration to rabbits. The i.m. injected liposomes showed a terminal half-life of 74 h and after 24 h 7 per cent of the administered lecithin was still in the plasma. Eight hours following the i.m. injection of the liposomes, the plasma levels of lonazolac were significantly higher compared to the reference. A portion of the liposomes was released from the muscle into the circulation. A great share of lonazolac was quickly interchanged between the liposomes and the surrounding tissue. In additional experiments small oligolamellar liposomes should be used to decrease the interchange of lonazolac and to enhance the plasma levels of liposomal incorporated lonazolac.

Animals↗
PubMed1984

Temperature-dependent drug release from large unilamellar liposomes.

The drug-release properties of large unilamellar liposomes were measured at temperatures near the lipid's phase-transition temperature. The liposomes were formed from a mixture of dipalmitoylphosphatidylcholine and dipalmitoylphosphatidylglycerol (4:1 by weight) by the reverse-phase evaporation process. These liposomes captured 25-35% of the radiolabeled anticancer drug cytosine [3H]-1-beta-arabinofuranoside in their aqueous compartment. They were stable in serum below the lipid's phase-transition temperature of 41 degrees C. Complete drug release occurred within seconds after the liposomes reached a temperature of 43 degrees C in serum. Addition of cholesterol or phosphatidylglycerol to the liposomal membrane reduced the drug-release temperature and broadened the range of drug release. These results show that suspensions of large unilamellar liposomes can be made to encapsulate a therapeutically useful quantity of drug that is rapidly and completely released at 43 degrees C in serum.

Blood↗
PubMed2000

Carotenoid-containing unilamellar liposomes loaded with glutathione: a model to study hydrophobic-hydrophilic antioxidant interaction.

Unilamellar liposomes are used as a simple two-compartment model to study the interaction of antioxidants. The vesicle membrane can be loaded with lipophilic compounds such as carotenoids or tocopherols, and the aqueous core space with hydrophilic substances like glutathione (GSH) ascorbate, mimicking the interphase between an aqueous compartment of a cell and its surrounding membrane. Unilamellar liposomes were used to investigate the interaction of GSH with the carotenoids lutein, beta-carotene and lycopene in preventing lipid peroxidation. Lipid peroxidation was initiated with 2,2'-azobis-[2,4-dimethylvaleronitrile] (AMVN). Malondialdehyde (MDA) formation was measured as an indicator of oxidation; additionally, the loss of GSH was followed. In liposomes without added antioxidant, MDA levels of 119 +/- 6 nmol/mg phospholipid were detected after incubation with AMVN for 2 h at 37 degrees C. Considerably lower levels of 57 +/- 8 nmol MDA/mg phospholipid were found when the liposomal vesicles had been loaded with GSH. Upon incorporation of beta-carotene, lycopene or lutein, the resistance of unilamellar liposomes towards lipid peroxidation was further modified. An optimal further protection was observed with 0.02 nmol beta-carotene/mg phospholipid or 0.06 nmol lycopene/mg phospholipid. At higher levels both these carotenoids exhibited prooxidant effects. Lutein inhibited lipid peroxidation in a dose-dependent manner between 0.02 and 2.6 nmol/mg phospholipid. With increasing levels of lycopene and lutein the consumption of encapsulated GSH decreased moderately, and high levels of beta-carotene led to a more pronounced loss of GSH. The data demonstrate that interactions between GSH and carotenoids may improve resistance of biological membranes towards lipid peroxidation. Different carotenoids exhibit specific properties, and the level for optimal protection varies between the carotenoids.

Antioxidants↗
PubMed1984

The effects of charge and size on the interaction of unilamellar liposomes with macrophages.

The effect of the positive surface charge of unilamellar liposomes on the kinetics of their interaction with rat peritoneal macrophages was investigated using three sizes of liposomes: small unilamellar vesicles (approx. 25 nm diameter), prepared by sonication, and large unilamellar vesicles (100 nm and 160 nm diameter), prepared by the Lipoprep dialysis method. Charge was varied by changing the proportion of stearylamine added to the liposomal lipids (egg phosphatidylcholine and cholesterol, molar ratio 10:2.5). Increasing the stearylamine content of large unilamellar vesicles over a range of 0-25 mol% enhanced the initial rate of vesicle-cell interaction from 0.1 to 1.4 microgram lipid/min per 10(6) cells, and the maximal association from 5 to 110 micrograms lipid/10(6) cells. Cell viability was greater than 90% for cells incubated with large liposomes containing up to 15 mol% stearylamine but decreased to less than 50% at stearylamine proportions greater than 20 mol%. Similar results were obtained with small unilamellar vesicles except that the initial rate of interaction and the maximal association were less sensitive to stearylamine content. The initial rate of interaction, with increasing stearylamine up to 25 mol%, ranged from 0.5 to 0.7 microgram lipid/min per 10(6) cells, and the maximal association ranged from 20 to 70 micrograms lipid/10(6) cells. A comparison of the number and entrapped aqueous volume of small and large vesicles containing 15 mol% stearylamine revealed that although the number of large vesicles associated was 100-fold less than the number of small vesicles, the total entrapped aqueous volume introduced into the cells by large vesicles was 10-fold greater. When cytochalasin B, a known inhibitor of phagocytosis, was present in the medium, the cellular association of C8-LUV was reduced approx. 25% but association of SUV increased approx. 10-30%. Modification of small unilamellar vesicles with an amino mannosyl derivative of cholesterol did not increase their cellular interaction over that of the corresponding stearylamine liposomes, indicating that cell binding induced by this glycolipid may be due to the positive charge of the amine group on the sugar moiety. The results demonstrate that the degree of liposome-cell interaction with macrophages can be improved by increasing the degree of positive surface charge using stearylamine. Additionally, the delivery of aqueous drugs to cells can be further improved using large unilamellar vesicles because of their greater internal volume. This sensitivity of macrophages to vesicle charge and size can be used either to increase or reduce liposome uptake significantly by this cell type

Amines↗
PubMed1985

Binding of hematoporphyrin derivative to membranes. Expression of porphyrin heterogeneity and effects of cholesterol studied in large unilamellar liposomes.

The binding of hematoporphyrin derivative to membrane was studied at the molecular level, employing fluorimetric techniques and using liposomes (large unilamellar) to model biological membranes. Two specific issues were probed: (a) the effect of increasing the porphyrin-liposome incubation period (37 degrees C, neutral pH, in the dark) from 2 h up to 24 h, with liposomes composed of PC or PC/cholesterol 7:3 (molar ratio); (b) the effects of membrane lipid composition, in terms of mol% cholesterol in PC/cholesterol liposomes, on the porphyrin-membrane binding equilibrium, for a long incubation period (16 h). The data were processed and found to be in good agreement with the following proposed model: With time (t greater than 2 h), the porphyrin fractions into three components, two of them binding to membrane with high and low affinities, respectively, the time effect reaching a plateau at 16 h. Linkage was observed between the slow process and changes in the available pools of each fraction. At sufficiently long incubations, the magnitude of each of the two binding fractions was found to be (roughly) 30%, independent of the membrane lipid composition. On the other hand, the magnitude of the binding constants was found to depend on the lipid composition, that of the high-affinity fraction decreasing from 9000 M-1 for 0% cholesterol, to 3000 M-1 for 40% cholesterol, then increasing back to 5000 M-1 upon further increase in cholesterol (to 50% mol) and that of the low-affinity fraction going from 1000 M-1, to 100 M-1, to 300 M-1 for similar lipid compositions. The origin of the time effect, in terms of porphyrin-specific processes, and the biological relevance of the present findings are discussed.

Cholesterol↗
PubMed1995

Selective boron delivery to murine tumors by lipophilic species incorporated in the membranes of unilamellar liposomes.

The nido-carborane species K[nido-7-CH3(CH2)15-7,8-C2B9H11] has been synthesized for use as an addend for the bilayer membrane of liposomes. Small unilamellar vesicles, composed of distearoylphosphatidylcholine/cholesterol, 1:1, and incorporating K[nido-7-CH3(CH2)15-7,8-C2B9H11] in the bilayer, have been investigated in vivo. The time-course biodistribution of boron delivered by these liposomes was determined by inductively coupled plasma-atomic emission spectroscopy analyses after the injection of liposomal suspensions in BALB/c mice bearing EMT6 mammary adenocarcinomas. At the low injected doses normally used (approximately 5-10 mg of boron per kg of body weight), peak tumor boron concentrations of approximately 35 micrograms of boron per g of tissue and tumor/blood boron ratios of approximately 8 were achieved. These values are sufficiently high for the successful application of boron neutron capture therapy. The bilayer-embedded boron compound may provide the sole boron source or, alternatively, a concentrated aqueous solution of a hydrophilic boron compound may also be encapsulated within the liposomes to provide a dose enhancement. Thus, the incorporation of both K[nido-7-CH3(CH2)15-7,8-C2B9H11] and the hydrophilic species, Na3[1-(2'-B10H9)-2-NH3B10H8], within the same liposomes demonstrated significantly enhanced biodistribution characteristics, exemplified by maximum tumor boron concentrations of approximately 50 micrograms of boron per g of tissue and tumor/blood boron ratios of approximately 6.

Animals↗
PubMed1983

Effects of liposome dose and the presence of lymphosarcoma cells on blood clearance and tissue distribution of large unilamellar liposomes in mice.

Large unilamellar liposomes (50 to 500 mumol of lipid per kg) were injected i.v. or i.p. into normal and lymphosarcoma-bearing mice. The percentage of the dose remaining in the blood and that accumulated in liver, spleen, and various other organs was measured 4 hr after injection. The results indicate that liposomes cause a dose-dependent saturation of the hepatic and splenic clearance capacities. One day after injection of 10(6) lymphosarcoma cells, the capacity of the tumor-bearing mice to eliminate liposomes from the blood (in a 4-hr period) was inhibited 30 to 50%. This could be ascribed to a decreased activity of the reticuloendothelial system caused by the tumor cells, as was indicated by the simultaneous inhibition of carbon clearance. Six days after injection of the lymphosarcoma cells, the elimination of liposomes from the blood in tumor-bearing mice was restored to the value in normal mice. The possible involvement of tumor cells in the uptake of liposomes by the liver was investigated morphologically after i.v. injection of peroxidase-containing liposomes into lymphosarcoma-bearing mice. Liposome-entrapped peroxidase activity was never observed in the tumor cells. The results presented here indicate that the lymphosarcoma cells do not directly participate in the hepatic accumulation of liposomes, although their mere presence may have significant indirect effects on the elimination of liposomes from the blood and on their tissue distribution.

Animals↗
PubMed2000

Electroinjection of colloid particles and biopolymers into single unilamellar liposomes and cells for bioanalytical applications.

A combined electroporation and pressure-driven microinjection method for efficient loading of biopolymers and colloidal particles into single-cell-sized unilamellar liposomes was developed. Single liposomes were positioned between a approximately 2-microm tip diameter solute-filled glass micropipet, equipped with a Pt electrode, and a 5-microm-diameter carbon fiber electrode. A transient, 1-10 ms, rectangular waveform dc voltage pulse (10-40 V/cm) was applied between the electrodes, thus focusing the electric field over the liposome. Dielectric membrane breakdown induced by the applied voltage pulse caused the micropipet tip to enter the liposome and a small volume (typically 50-500 x 10(-15) L) of fluorescein, YOYO-intercalated T7-phage DNA, 100-nm-diameter unilamellar liposomes, or fluorescent latex spheres could be injected into the intraliposomal compartment. We also demonstrate initiation of a chemical intercalation reaction between T2-phage DNA and YOYO-1 by dual injection into a single giant unilamellar liposome. The method was also successfully applied for loading of single cultured cells.

Biopolymers↗
PubMed2000

Interactions of cyclodextrins with dipalmitoyl, distearoyl, and dimyristoyl phosphatidyl choline liposomes. A study by leakage of carboxyfluorescein in inner aqueous phase of unilamellar liposomes.

The interaction of cyclodextrins (CDs) with L-alpha-dipalmitoyl phopsatidyl choline (DPPC), L-alpha-distearoyl phosphatidyl choline (DSPC), and L-alpha-dimyristoyl phosphatidyl choline (DMPC) unilamellar liposomes was investigated by the leakage of carboxylfluorescein (CF) entrapped in the inner aqueous phase of liposomes, at 25 degrees C (DPPC and DSPC liposomes) and at 5 degrees C (DMPC liposomes). The efficiency of CDs for CF leakage was remarkable in the order of heptakis (2,6-di-O-methyl)-beta-CD (DOM-beta-CD) > alpha-CD > heptakis (2,3,6-tri-O-methy)-beta-CD (TOM-beta-CD) from DPPC liposomes, in the order of DOM-beta-CD > TOM-beta-CD > alpha-CD from DSPC liposomes and in the order of alpha-CD > DOM-beta-CD > TOM-beta-CD from DMPC liposomes. The other CDs used in the present studies, beta-CD, 2-hydroxylpropyl beta-CD, and gamma-CD scarcely induced the CF leakage from above the three liposomes. From the profiles of % CF leakage, together with measurements of differential scanning calorimetry, it was found that hydrophobic DOM-beta-CD penetrates the matrix of the liposomes to interact with them as well as TOM-beta-CD, and that less hydrophobic alpha-CD exists at the surface of the membrane to interact with the liposomes. Further, it was found that the interaction of CDs with liposomes changes depending not only on the length of fatty acid chain of phospholipid (condensation force and hydrophobicity) but also the hydrophobicity and the cavity size of CD.

1,2-Dipalmitoylphosphatidylcholine↗
PubMed2005

Formation of homogeneous unilamellar liposomes from an interdigitated matrix.

Phospholipid-ethanol-aqueous mixtures containing bilayer-forming lipids and 20-50 wt.% of water form viscous gels. Further hydration of these gels results in the formation of liposomes whose morphology depends upon the lipid type. Upon hydration of gels containing mixtures of the lipids 1-palmitoyl-2-oleoyl-phosphatidylcholine (POPC) and 1-palmitoyl-2-oleoyl-phosphatidylglycerol (POPG), small homogeneous and unilamellar liposomes were produced. In contrast, hydration of gels containing only POPC resulted in formation of large multilamellar liposomes. Likewise, mulitlamellar liposomes resulted when this method was applied to form highly fusogenic liposomes comprised of the novel negatively charged N-acyl-phosphatidylethanolamine (NAPE) mixed with di-oleoyl-phosphatidylcholine (DOPC) (7:3) [T. Shangguan, C.C. Pak, S. Ali, A.S. Janoff, P. Meers, Cation-dependent fusogenicity of an N-acyl phosphatidylethanolamine, Biochim. Biophys. Acta 1368 (1998) 171-183]. In all cases, the measured aqueous entrapment efficiencies were relatively high. To better understand how the molecular organization of these various gels affects liposome morphology, we examined samples by freeze-fracture transmission electron microscopy and X-ray diffraction. We found that phospholipid-ethanol-water gels are comprised of highly organized stacks of lamellae. A distinct feature of the gel samples that result in small unilamellar liposomes is the combination of acyl chain interdigitation and net electrostatic charge. We speculate that the mechanism of unilamellar liposome formation proceeds via formation of stalk contacts between neighboring layers similar to membrane hemifusion intermediates, and the high aqueous entrapment efficiencies make this liposome formation process attractive for use in drug delivery applications.

Ethanol↗
PubMed1988

Mechanisms of membrane protein insertion into liposomes during reconstitution procedures involving the use of detergents. 1. Solubilization of large unilamellar liposomes (prepared by reverse-phase evaporation) by triton X-100, octyl glucoside, and sodium cholate.

The mechanisms governing the solubilization by Triton X-100, octyl glucoside, and sodium cholate of large unilamellar liposomes prepared by reverse-phase evaporation were investigated. The solubilization process is described by the three-stage model previously proposed for these detergents [Lichtenberg, D., Robson, R.J., & Dennis, E.A.(1983) Biochim. Biophys. Acta 737, 285-304]. In stage I, detergent monomers are incorporated into the phospholipid bilayers until they saturate the liposomes. At that point, i.e., stage II, mixed phospholipid-detergent micelles begin to form. By stage III, the lamellar to micellar transition is complete and all the phospholipids are present as mixed micelles. The turbidity of liposome preparations was systematically measured as a function of the amount of detergent added for a wide range of phospholipid concentrations (from 0.25 to 20 mM phospholipid). The results allowed a quantitative determination of RSat, the effective detergent to lipid molar ratios in the saturated liposomes, which were 0.64, 1.3, and 0.30 for Triton X-100, octyl glucoside, and sodium cholate, respectively. The corresponding ratios in the mixed micelles, RSol, were 2.5, 3.8, and 0.9 mol of detergent/mol of phospholipid. The monomer concentrations of the three detergents in the aqueous phase were also determined at the lamellar to micellar transitions (0.18, 17, and 2.8 mM, respectively). These transitions were also investigated by 31P NMR spectroscopy, and complete agreement was found with turbidity measurements. Freeze-fracture electron microscopy and permeability studies in the sublytic range of detergent concentrations indicated that during stage I of solubilization detergent partitioning between the aqueous phase and the lipid bilayer greatly affects the basic permeability of the liposomes without significantly changing the morphology of the preparations. A rough approximation of the partition coefficients was derived from the turbidity and permeability data (K = 3.5, 0.09, and 0.11 mM-1 for Triton X-100, octyl glucoside, and sodium cholate, respectively). It is concluded that when performed systematically, turbidity measurements constitute a very convenient and powerful technique for the quantitative study of the liposome solubilization process by detergents.

Bacteriorhodopsins↗
PubMed2006

Preparation of submicron unilamellar liposomes by freeze-drying double emulsions.

A novel method is described for the preparation of sterile submicron unilamellar liposomes. The method is based on the lyophilization of double emulsions containing disaccharides as lyoprotectants in both the inner and outer aqueous phase. Using various phospholipids or mixtures of lipids as emulsifiers, the double emulsions can be prepared by a two-step emulsification, including hydrophilic agents in the inner aqueous phase or lipophilic agents in the oil phase. Then, the double emulsions are lyophilized after sterilization by passing them through a 0.22-microm pore filter. Rehydration of the lyophilized products results in liposomes with a relatively high encapsulation efficiency (for calcein, 87%; 5-fluorouracil, 19%; flurbiprofen, 93%) and a size below 200 nm measured by the dynamic light scattering technique (DLS) and the atomic force microscopy (AFM). The liposomes were found to be unilamellar from freeze-fracture electron micrographs and X-ray diffraction patterns. In addition, the liposomes can be reconstituted just before use by rehydration of the lyophilized products which are relatively stable. Thus, this reproducible and simple technique can be used to prepare sterilized, submicron unilamellar liposomes with a relatively high encapsulation efficiency, and excellent stability during long-term storage.

Emulsions↗