Pure dppc bilayers exhibit characteristic transitions with low enthalpy changes and a sharp main transition tm, both of which. Effect of encapsulation on phase transition temperature of. Soluteinduced shift of phase transition temperature in di. The phase transition temperature was determined by the differential scanning calorimetry dsc. Liposomes modified with temperatureresponsive polymers. Supplementary information effect of phase transition.
A copolymer of nisopropylacrylamide and octadecyl acrylate was synthesized by radical copolymerization in dioxane using azobisisobutyronitrile as the initiator. Temperature sensitive control of liposomecell adhesion. The c70exchange reaction occurred completely at temperatures above the phase transition temperature tm of the liposomes. Evaluation of phase transition temperature of liposomes by using the tautomerism. Formation and regulation of fullereneincorporation in. Briefly, lipid mixtures are first dissolved in ethanol and then hydrated at a temperature above the lipid main phase transition with a hydration solution i. Liposomes are a good model system for the cell membrane. Phase transition temperature reduction and glass formation in dehydroprotected lyophilized liposomes. Mayera,b,e, katarina edwardsc adepartment of advanced therapeutics, the british columbia cancer agency research centre, 601 west 10th avenue, vancouver, bc, canada v5z 1l3 bfaculty of pharmaceutical sciences, university of. Preparation of liposomes mlvs were made by hydrating lipid powder in the appropriate solution at a temperature of at least 108c above its phase transition temperature for 1 h with intermittent vortexing. Transition temperature of phospholipids determined by nps. Liposomes modified with temperatureresponsive polymers are tuned for cellular uptake. Whats is the effect of transition temperature of a lipid in liposome formation.
Preparation of dppc liposomes using probetip sonication. Stealth liposomes or cryptosomes have been used to improve the efficiency of drug delivery by liposomes. A liposome is a vesicle composed of phospholipids with a structure similar to the biological membrane. Membrane permeabilization of phosphatidylcholine liposomes. If you are viewing this page on a mobile device or would like to print this information for offline use, we have formatted the data into an easy to read pdf. At this temperature, dppc liposomes are in the gel phase. The leakage from these liposomes rapidly increases.
After addition of the hydrating medium, the lipid suspension should be maintained above the tc. Low amounts of sucrose are sufficient to depress the phase. It is shown that the fullereneexchange reaction from the cyclodextrin cavity to liposomes, to prepare lipid membraneincorporating fullerenes, occurred above the phase transition temperature tm of liposomes. Experimental biochemistry i liposome permeability and phase transition 114 c. It inserts into membrane with hydroxyl group oriented towards aqueous. Relationship between phase transition temperature and. The liposomes with lipid transition temperature slightly higher than the body temperature elicit higher immune response, which may be due to formation of less rigid lipid and thereby enhance mucosal adherence. Usually liposomes have low permeability to the encapsulated molecules unless the molecule is membrane permeable. In an effort to establish an effective method to produce liposomes from the lipid, dipalmitoylphosphatidylcholine or dppc, we have found important aspects that must be taken into consideration. The glass transition in polymers is an important type of phase transition. Pdf effect of gentamicin on the transition temperature. The phase transition temperature of liposomes, which depends on the tc of the constituent lipids, was an important factor in liposome stability. Liposomes lipid vesicles are formed when thin lipid films or lipid cakes are hydrated and stacks of liquid crystalline.
What is the effect of the phase transition temperature of. Pdf we investigated the effect of the phase transition temperature t of phospholipid in liposomes on the stability of incorporated retinol. Liposomes can be composed of naturallyderived phospholipids with mixed lipid chains like egg phosphatidylethanolamine, or of pure surfactant. This temperature is also known as transition temperature tc.
To this osmolyte solution you will add an aliquot of the aqueous liposome stock solution described above. Physicochemical properties of liposomes depend on many factors such as ionic strength, ph and temperature. Differential scanning calorimetry of bilayer membrane. The phase transition temperature is defined as the temperature required to induce a change in the lipid physical state from the ordered gel phase, where the hydrocarbon chains are fully extended and closely packed, to the disordered liquid crystalline phase, where the hydrocarbon chains are randomly oriented and fluid. The lcsts of pnipaamcodmapaam and pnipaamcodmaam were observed at 41. Liposomes are produced when the phospholipid bilayer forms around an aqueous cavity. Influence of lipid composition on the phase transition temperature of liposomes composed of both dppc and hspc. L aphosphatidylcholine p3556 product information sheet.
Cell membranes, however, also contain embedded proteins and other lipids. Liposomes are an important tool and have gained much attention for their promise as an effective means of delivering small therapeutic compounds to targeted sites. With a given polar head, the transition temperature depends on the type and length of the acyl chains the longer the chain, the higher the temperature. Influence of lipid composition on the phase transition temperature of liposomes composed of both dppc and hspc article pdf available in drug development and industrial pharmacy 392 march. Remarkably, liposomes with phase transition temperature around the body temperature are observed to. The effect of different lipid components on the in vitro. Two dodecyl groups were incorporated into the termini of these copolymers as an anchor for the fixation to. Determination of the main phase transition temperature of. The phase transition temperature of liposomes, which depends on. What are liposomes liposomes are concentric bilayered vesicles in which an aqueous core is entirely enclosed by a membranous lipid bilayer mainly composed of. Thermal analysis of phase transition behaviour in liposomes. The same product is available as a solution in chloroform as product no.
In the absence of cholesterol, liposome permeability. Pdf phase transition temperature reduction and glass. These liposomes captured 2535% of the radiolabeled anticancer drug cytosine 3 h1. Thermotropic phase transitions of pure lipids in model membranes and their modifications by membrane proteins, dr. Effect of polymer phase transition behavior on temperature.
Destabilization of phosphatidylethanolamine liposomes at the. Whats is the effect of transition temperature of a lipid. Three kinds of copolymers of nisopropylacrylamide nipam with the same conformational transition temperature and varying transition endotherms were synthesized with nacryloylpyrrolidine apr, n,ndimethylacrylamide dmam, and nisopropylmethacrylamide nipmam as the comonomers. The phase transition behavior of the prepared polymers was established from the temperaturedependent transmittance change of the solution.
Pdf determination of the main phase transition temperature of. What is the effect of the phase transition temperature of the lipid on the liposome formulation. Recently, several studies have been performed using liposome based oral nanovaccine and are discussed in the following section. The glass transition temperature, t g, is the temperature at which amorphous noncrystalline polymers are converted from a brittle, glasslike form to a rubbery, flexible form. Temperature and rigiditymediated rapid transport of. Pdf effect of phase transition temperature of phospholipid on the. Influence of cationic lipids on the stability and membrane. A liposomal formulation able to incorporate a high content. In order to develop a novel temperature sensitive liposome, liposomes bearing poly nisopropylacrylamide, which shows a lower critical solution temperature lcst, were prepared and release behaviors of these liposomes were investigated. Differential scanning calorimetry dsc is the technique which has been most widely applied to liposomal systems. For liposomes formed from pure phosphatidylcholine pc, see fig. Phase transitions of lipids and liposomes mettler toledo.
Lipids all have a temperature at which their fluidity changes. The parameters derived from dsc analysis include the onset temperature of the transition t, and the temperature at the peak t, frequency denoted t, when referring to the gel to liquidcrystalline phase transition. Effect of phase transition temperature of liposomes on preparation of fullereneencapsulated liposomes by the fullereneexchange reaction atsushi ikeda, yoshihiko kawai, junichi kikuchi and motofusa akiyama graduate school of materials science, nara institute of science and technology, 89165 takayama, ikoma, nara 6300192, japan. The effect of different lipid components on the in vitro stability and release kinetics of liposome formulations.
The liposomes, composed of naturally unsaturated and hydrogenated phosphatidylcholines, with significant phase transition temperature difference, were prepared and characterized. Liposomes have a characteristic t c transition temperature, at which they transit from gel phase to liquid crystalline phase. This monomertomicellar transition process is extremely temperaturesensitive. Below their transition temperature, liposomes are osmotically insensitive structures but, on addition of gramicidin a, the water permeability so increased that the. Liposomes formation is possible only if the temperature is above transition temperature. Here, we report a temperature and rigiditymediated rapid transport mechanism by which liposomes attain optimal diffusivity near a phase transition temperature. Cholesterol by itself do not form a bilayer structure, it acts as fluidity buffer. Pdf liposomes, sphereshaped vesicles consisting of one or more phospholipid bilayers, were first described in the mid60s. Evaluation of phase transition temperature of liposomes by. The encapsulated rugs are release at crystalline phase. The degree of encapsulation of 5fluorouracil 5fu and vinorelbine vin to dipalmitoylphosphatidylcholine dppc liposomes was estimated using uvvis spectroscopy. The effect of temperature on the permeability of nonelectrolytes across liposomal membranes above and below their transition temperature has been studied by using an osmotic method.
The liposomes exhibited a high content of paclitaxel, which was incorporated within the segregated microdomains coexisting on phospholipid bilayer of liposomes. Effect of phase transition temperature of liposomes on. Effects of temperature, acyl chain length, and flowrate. The effect of different lipid components on the in vitro stability and. Temperaturedependent drug release from large unilamellar. The rigidity of the membrane is also responsible for better stability. Lipid extrusion is a technique in which a lipid suspension is forced through a. Hepes buffered 10% sucrose solution or an ammonium sulfate solutions.
Liposomes a novel drug delivery system from miss snehal k. Effect of gentamicin on the transition temperature and permeability to glycerol of phosphatidylinositolcontaining liposomes. Remarkably, liposomes with phase transition temperature around the body temperature are observed to overcome multiple biological barriers and show substantial improvement in drug. Cholesterol addition to pc liposomes increased membrane stability towards leakiness. Temperature sensitization of liposomes by use of n. Evaluation of phase transition temperature of liposomes by using tautomerism of benzoylacetoanilide and effects of cholesterol. It has been proposed that the lyoprotection of liposomes depends on the depression of the gel to liquidcrystalline phase transition temperature tm of the dry membranes below ambient and on the prevention of membrane fusion by sugar glass formation, because both lead to. The fullereneexchange reaction from a cyclodextrin cavity to liposomes represents one of the best methods to prepare lipid membraneincorporated 70fullerenes c70. Rapid report disc formation in cholesterolfree liposomes. The relationship between the gelliquid ctystal phase transition temperature tm of dipalmitoylphosphatidylcho line dppc liposomes and the protonation. Dmso was found to dehydrate the phospholipid headgroups while raising the membrane phase transition temperature, whereas the other cpas caused an increase in the hydration level of the lipid headgroups while decreasing the membrane phase transition temperature.
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