scholarly journals Lipid Vesicles and Other Polymolecular Aggregates—From Basic Studies of Polar Lipids to Innovative Applications

2021 ◽  
Vol 11 (21) ◽  
pp. 10345
Author(s):  
Peter Walde ◽  
Sosaku Ichikawa
Keyword(s):  
Interdisciplinary Collaboration ◽  
Lipid Vesicles ◽  
Average Diameter ◽  
Bilayer Membrane ◽  
Polar Lipids ◽  
Molecular Systems ◽  
Hydrophobic Compounds ◽  
Life Saving ◽  
Internal Volume ◽  
Basic Studies

Lipid vesicles (liposomes) are a unique and fascinating type of polymolecular aggregates, obtained from bilayer-forming amphiphiles—or mixtures of amphiphiles—in an aqueous medium. Unilamellar vesicles consist of one single self-closed bilayer membrane, constituted by the amphiphiles and an internal volume which is trapped by this bilayer, whereby the vesicle often is spherical with a typical desired average diameter of either about 100 nm or tens of micrometers. Functionalization of the external vesicle surface, basically achievable at will, and the possibilities of entrapping hydrophilic molecules inside the vesicles or/and embedding hydrophobic compounds within the membrane, resulted in various applications in different fields. This review highlights a few of the basic studies on the phase behavior of polar lipids, on some of the concepts for the controlled formation of lipid vesicles as dispersed lamellar phase, on some of the properties of vesicles, and on the challenges of efficiently loading them with hydrophilic or hydrophobic compounds for use as delivery systems, as nutraceuticals, for bioassays, or as cell-like compartments. Many of the large number of basic studies have laid a solid ground for various applications of polymolecular aggregates of amphiphilic lipids, including, for example, cubosomes, bicelles or—recently most successfully—nucleic acids-containing lipid nanoparticles. All this highlights the continued importance of fundamental studies. The life-saving application of mRNA lipid nanoparticle COVID-19 vaccines is in part based on year-long fundamental studies on the formation and properties of lipid vesicles. It is a fascinating example, which illustrates the importance of considering (i) details of the chemical structure of the different molecules involved, as well as (ii) physical, (iii) engineering, (iv) biological, (v) pharmacological, and (vii) economic aspects. Moreover, the strong demand for interdisciplinary collaboration in the field of lipid vesicles and related aggregates is also an excellent and convincing example for teaching students in the field of complex molecular systems.

Nanoemulsions Loaded with Amphotericin B: Development, Characterization and Leishmanicidal Activity

2019 ◽  
Vol 25 (14) ◽  
pp. 1616-1622 ◽  
Author(s):  
Gabriela Muniz Félix Araújo ◽  
Gabriela Muniz Félix Araújo ◽  
Alana Rafaela Albuquerque Barros ◽  
Alana Rafaela Albuquerque Barros ◽  
João Augusto Oshiro-Junior ◽  
...  
Keyword(s):  
Amphotericin B ◽  
Average Diameter ◽  
Isopropyl Myristate ◽  
Neglected Diseases ◽  
Clinical Form ◽  
Hydrophobic Compounds ◽  
Internal Phase ◽  
Oil In Water ◽  
Spherical Structures ◽  
Lipid Formulations

Leishmaniasis is one of the most neglected diseases in the world. Its most severe clinical form, called visceral, if left untreated, can be fatal. Conventional therapy is based on the use of pentavalent antimonials and includes amphotericin B (AmB) as a second-choice drug. The micellar formulation of AmB, although effective, is associated with acute and chronic toxicity. Commercially-available lipid formulations emerged to overcome such drawbacks, but their high cost limits their widespread use. Drug delivery systems such as nanoemulsions (NE) have proven ability to solubilize hydrophobic compounds, improve absorption and bioavailability, increase efficacy and reduce toxicity of encapsulated drugs. NE become even more attractive because they are inexpensive and easy to prepare. The aim of this work was to incorporate AmB in NE prepared by sonicating a mixture of surfactants, Kolliphor® HS15 (KHS15) and Brij® 52, and an oil, isopropyl myristate. NE exhibited neutral pH, conductivity values consistent with oil in water systems, spherical structures with negative Zeta potential value, monomodal size distribution and average diameter of drug-containing droplets ranging from 33 to 132 nm. AmB did not modify the thermal behavior of the system, likely due to its dispersion in the internal phase. Statistically similar antileishmanial activity of AmB-loaded NE to that of AmB micellar formulation suggests further exploring them in terms of toxicity and effectiveness against amastigotes, with the aim of offering an alternative to treat visceral leishmaniasis.

Bilayer Membrane Bending Stiffness by Tether Formation From Mixed PC-PS Lipid Vesicles

1990 ◽  
Vol 112 (3) ◽  
pp. 235-240 ◽  
Author(s):  
J. Song ◽  
R. E. Waugh
Keyword(s):  
Present Report ◽  
Membrane Surface ◽  
Lipid Vesicles ◽  
Phosphatidyl Serine ◽  
Bilayer Membrane ◽  
Bending Stiffness ◽  
New Approach ◽  
Lipid Mixtures ◽  
Membrane Bending ◽  
Membrane Surface Charge

Recently, a new approach to measure the bending stiffness (curvature elastic modulus) of lipid bilayer membrane was developed (Biophys. J., Vol. 55; pp. 509–517, 1989). The method involves the formation of cylindrical membrane strands (tethers) from bilayer vesicles. The bending stiffness (B) can be calculated from measurements of the tether radius (Rt) as a function of the axial force (f) on the tether: B =f·Rt/2π. In the present report, we apply this method to determine the bending stiffness of bilayer membranes composed of mixtures of SOPC (1-stearoyl-2-oleoyl phosphatidyl choline) and POPS (1-palmitoyl-2-oleoyl phosphatidyl serine). Three different mixtures were tested: pure SOPC, SOPC plus 2 percent (mol/mol) POPS, and SOPC plus 16 percent POPS. The bending stiffness determined for these three different lipid mixtures were not significantly different (1.6–1.8×10-12 ergs). Because POPS carries a net negative charge, these results indicate that changes in the density of the membrane surface charge have no effect on the intrinsic rigidity of the membrane. The values we obtain are consistent with published values for the bending stiffness of other membranes determined by different methods. Measurements of the aspiration pressure, the tether radius and the tether force were used to verify a theoretical relationship among these quantities at equilibrium. The ratio of the theoretical force to the measured force was 1.12 ± 0.17.

scholarly journals Synthetic Cell as a Platform for Understanding Membrane-Membrane Interactions

Membranes ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 912
Author(s):  
Bineet Sharma ◽  
Hossein Moghimianavval ◽  
Sung-Won Hwang ◽  
Allen P. Liu
Keyword(s):  
Membrane Fusion ◽  
Intercellular Communication ◽  
Lipid Vesicles ◽  
Bilayer Membrane ◽  
Future Research ◽  
Membrane Interactions ◽  
Protein Insertion ◽  
Synthetic Cell ◽  
Challenges And Opportunities ◽  
Synthetic Cells

In the pursuit of understanding life, model membranes made of phospholipids were envisaged decades ago as a platform for the bottom-up study of biological processes. Micron-sized lipid vesicles have gained great acceptance as their bilayer membrane resembles the natural cell membrane. Important biological events involving membranes, such as membrane protein insertion, membrane fusion, and intercellular communication, will be highlighted in this review with recent research updates. We will first review different lipid bilayer platforms used for incorporation of integral membrane proteins and challenges associated with their functional reconstitution. We next discuss different methods for reconstitution of membrane fusion and compare their fusion efficiency. Lastly, we will highlight the importance and challenges of intercellular communication between synthetic cells and synthetic cells-to-natural cells. We will summarize the review by highlighting the challenges and opportunities associated with studying membrane–membrane interactions and possible future research directions.

Interdigitation-fusion: a new method for producing lipid vesicles of high internal volume

1994 ◽  
Vol 1195 (2) ◽  
pp. 237-244 ◽  
Author(s):  
Patrick L. Ahl ◽  
Lu Chen ◽  
Walter R. Perkins ◽  
Sharma R. Minchey ◽  
Lawrence T. Boni ◽  
...  
Keyword(s):  
Lipid Vesicles ◽  
New Method ◽  
Internal Volume

scholarly journals Potential Enhancement of Metformin Hydrochloride in Lipid Vesicles Targeting Therapeutic Efficacy in Diabetic Treatment

2021 ◽  
Vol 22 (6) ◽  
pp. 2852
Author(s):  
Emmanuel Chekwube Ossai ◽  
Augustine Chidi Madueke ◽  
Benjamin Emenike Amadi ◽  
Martins Obinna Ogugofor ◽  
Audu Mumuni Momoh ◽  
...  
Keyword(s):  
Therapeutic Efficacy ◽  
Lipid Vesicles ◽  
Average Diameter ◽  
Diabetic Rats ◽  
Metformin Hydrochloride ◽  
Release Formulation ◽  
Extended Release Formulation ◽  
Emulsion Droplets ◽  
Oxidative Stress Status ◽  
Diabetic Treatment

The potential enhancement of metformin hydrochloride (MH) loaded in lipid vesicles targeting therapeutic efficacy on alloxan-induced diabetic rats was investigated. This involved lipid vesicles formulated with homogenously distributed nano-sized particles by a novel integrated process of multiple emulsification by membrane and solvent evaporation. The average diameter of the water-in-oil (W1/O), W1/O/W2 emulsion droplets, and lipid vesicles was 192 nm, 52 µm, and 173 nm, respectively. The entrapment yield of metformin hydrochloride (MH) in the prepared lipid vesicles was 40.12%. The metformin hydrochloride-loaded lipid vesicles (MH-LLVs) sustained the release of the entrapped drug over a 12-h period and reduced the plasma glucose level of diabetic rats by 77.4% compared with free MH solution (2-h period and 58.2%, respectively) after one week post-diabetic treatment through oral administration of MH-LLV and the free drug. The remarkable improvement in the biochemical parameters recorded in the MH-LLV-treated animals compared with those that received free MH solutions depicted an enhanced kidney function, liver function, as well as oxidative stress status. Pancreatic histology depicted a pancreas with intralobular ducts (ID) and exocrine secretory acini that characterize an intact pancreas, which suggests the ability of the MH-LLVs to restore pancreatic cells to normal, on a continued treatment. Overall, MH-LLV appears an encouraging extended-release formulation with enhanced bioavailability, sustained release, and improved antihyperglycemic potentials.

A New Design for Floating Offshore Platforms

2012 ◽  
Author(s):  
S. V. Khonsari ◽  
G. L. England ◽  
E. Moradkhan ◽  
A. R. Valikhani ◽  
M. R. Bahadori
Keyword(s):  
Cost Effective ◽  
Offshore Platforms ◽  
Moment Arms ◽  
New Family ◽  
Life Saving ◽  
Wide Range ◽  
Efficient Alternative ◽  
The Stability ◽  
Basic Studies ◽  
Floating Platforms

While for shallow waters the use of old offshore jackets still seems efficient and justifiable, for deep and ultra-deep waters such platforms cannot be used. During the past few decades the old generation of fixed offshore platforms was succeeded by the new floating platforms and new designs such as FPSOs. A new family of floating offshore platforms has been developed. These should be able to respond to size, weight and space for operating equipment, i.e. they can be constructed to have a wide range of load-bearing capacities. Use is made of the old concept of Life Saving Tubes, which in their simplest form can be a toroidal shaped tyre inner tube. The Torus-shaped idea can be further extended to other shapes obtained either by revolving any plane closed curve or poly-line about a coplanar axis which does not intersect it, or by extruding the curve/poly-line through a closed path. The preliminary ‘structural’ calculations carried out on various samples of the torus-shaped members of this family of platforms showed that theoretically they can be designed to carry as much load as required and provide the users with the required space on the water. Moreover, basic studies of the stability of such systems in water showed their large metacentric heights as well as large righting moment arms, hence their high degree of stability. This stability can be further increased by using other versions of this idea with more efficient toroidal shapes. Furthermore, apparently, much study is required however to establish this idea as a viable, cost-effective and efficient alternative for current generations of offshore floating platforms.

Effect of different drugs on a cytochrome c – phospholipid bilayer membrane

1978 ◽  
Vol 56 (4) ◽  
pp. 555-563
Author(s):  
Michael A. Singer
Keyword(s):  
Cytochrome C ◽  
Protein Binding ◽  
Lipid Vesicles ◽  
Bilayer Membrane ◽  
Fatty Acyl ◽  
Phospholipid Bilayer ◽  
Butylated Hydroxytoluene ◽  
Na Permeability ◽  
Na Efflux ◽  
Temperature Interaction

Liposomes were prepared from dipalmitoyl phosphatidylcholine and dicetylphosphate and their interaction with the extrinsic membrane protein cytochrome c examined in terms of changes in 22Na permeability, electrophoretic mobility, protein binding, and motion of an incorporated spin label. The amount of cytochrome c bound displays no significant temperature dependence over the temperature range studied (from 30 to 55 °C) whereas cytochrome c causes an increase in 22Na efflux only above the phospholipid phase transition temperature. Interaction of the protein with the lipid vesicles causes no significant disturbance in the bilayer interior as monitored by the motion of the incorporated spin probe. The drugs 2,4-dinitrophenol and ethacrynic acid, both of which increase the magnitude of the vesicle negative charge, enhance both cytochrome c binding and its effect on 22Na permeability. In contrast, the local anesthetic dibucaine, which induces a positive surface charge on these liposomes, reduces both protein binding and the protein-induced increase in 22Na efflux. Finally, the chemicals butylated hydroxytoluene, 2-tert-butylphenol, and tert-butylbenzene, all of which cause early 'melting' of the phospholipid fatty acyl chains, block the capacity of cytochrome c to enhance 22Na permeability while having no effect on its binding to the vesicles.

scholarly journals Physical stability of microliposomes in bene (Pistacia atlantica) oil with different formulations

2020 ◽  
Vol 12 (SP1) ◽  
pp. 41-49
Author(s):  
Mahsa Nikkhah ◽  
Zhaleh Khoshkhoo ◽  
Seyed Ebrahim Hosseini ◽  
Peyman Mahasti Shotorbani ◽  
Afshin Akhondzadeh Basti
Keyword(s):  
Particle Size ◽  
Zeta Potential ◽  
Encapsulation Efficiency ◽  
Physical Stability ◽  
Average Diameter ◽  
Pistacia Atlantica ◽  
Beneficial Effects ◽  
Hydrophobic Compounds ◽  
Amphiphilic Compounds ◽  
Bene Kernel Oil

Bene oil (pistacia atlantica), as a plant source, is rich in phenolic and tocopherol compounds and has significant antioxidant, therapeutic and antimicrobial effects. Encapsulation of hydrophobic compounds in liposome system is an ideal solution for protecting them against destruction during storage. An important advantage of liposomes is the encapsulation of hydrophilic, hydrophobic and amphiphilic compounds by using natural phospholipids, such as lecithin, with beneficial effects. The aim of this study is to encapsulate the bene kernel oil in the form of microliposomes. For this purpose, the effect of composition of liposomes based on lecithin and cholesterol was studied using the Mozafari method. Liposomes are prepared using lecithin and cholesterol in the ratios of 60:0, 50:10, 40:20 and 30:30. Particle size, size distribution, zeta potential and encapsulation efficiency were charac-terised. According to the result, the size of liposomes was dependent on their composition, but the wasaffected significantly affected by adding cholesterol (P < 0.05). Average diameter of the particles was between 4 and 9 µm. Liposome with a ratio of 40:20 had the smallest size. By applying cholesterol, zeta potential increased from 16.4 mV to 32.39 mV, which indicates electrostatic stability of liposomes. In general, with encapsulation efficiency of 84.33%, the ratio of 40:20 is considered as an ideal concentration in the formulation of microliposomes. Based on the results, bene oil-loaded liposomes with a lecithin:cholesterol formulation ratio of :as 40:20 was chosen as an optimal formulation because of its smaller particle size, higher zeta potential and suitable stability, which can be used in trapping, delivering and releasing hydrophilic, adipose-friendly and amphiphilic compounds (dual-friendly).

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