Nano letters how to stabilize phospholipid liposomes. This might be attributed to the steric stabilization provided by tween 80. Servos and juewen liu department of chemistry and waterloo institute for nanotechnology, department of biology, university of waterloo, 200. Cytotoxic activity of chemotherapeutic agents can be enhanced by sitespecific delivery or by combination with other less toxic agents.
Author links open overlay panel emmanuelle roux 1 romain stomp 2 suzanne giasson 2 michel. Steric stabilization of phospholipid vesicles by block. Preparation and evaluation of sterically stabilized liposomes. The macrophage uptake of the sterically stabilized liposomes was comparable to that of liposomes containing lipids and cholesterol. Pdf steric stabilization of eggphosphatidylcholine. Pdf longterm stability of sterically stabilized liposomes by. We have utilized the wellcharacterized binding interactions of blood coagulation proteins with ps containing liposomes as a model for evaluating the surface properties of peg on such liposomes. They are rapidly cleared from the circulation by the macrophages which are located mainly in the liver, spleen, and bone marrow. Impact of membrane fluidity on steric stabilization by. This work characterizes interactions between a cationic graft copolymer, peograftpolyethylenimine peogpei and negatively charged liposomes composed of 80% wt dipalmitoylphosphatidylcholine dppc and 20% wt diphosphatidylglycerol. The role of steric stabilization in the mechanism by which these polymers inhibit hemagglutination was investigated. Liposomes as drug delivery system literature covering the components, classification, as well as the. Steric stabilization has been proposed as a theoretical basis for the results and some initial results testing this hypothesis have been reported.
Pegylation of paclitaxelloaded cationic liposomes drives. Pdf liposomes are widely investigated for their use as drug delivery systems, where they have to meet strict stability criteria. Martin and lasic, 1991 would predict a reduction in electrophoretic mobility. Sterically stabilized liposomes in electrophoretic mobility. Polyethylene glycolmediated steric stabilization of. Liposomes that destabilize at mildly acidic ph are efficient tools for delivering watersoluble drugs into the cell cytoplasm.
The maximum lc value was obtained at the ratio of 8. Steric stabilization of liposomes by phresponsive nisopropylacrylamide copolymer article in journal of pharmaceutical sciences 918. Modes of liposome action liposomes as drug delivery systems can offer several advantages over conventional. Steric stabilization of eggphosphatidylcholine liposomes. Liposomes in the studies of the evolution of life 211 extraterrestrial origin of amphiphilic lipids 212 membranes, cholesterol and cell communication 212. Investigation of stabilization mechanisms for colloidal. Applications of liposomes dr baumann cosmetics canada. Liposomes and the use of zeta potential measurements to. Steric stabilization can be achieved by covering the surface with an adsorbed layer of long, bulky molecules to prevent the aggregation of the liposomes. Steric stabilizers for cubic phase lyotropic liquid.
Steric stabilization of fusogenic liposomes by a lowph sensitive peg. Kuhl department of chemical engineering and materials science, university of california, davis, one shields avenue, davis, california 95616, united states abstract. The purpose of this chapter is to collate and collectively interpret studies in the field of steric stabilization of this important emerging class of nanoparticles for drug and medical imaging agent delivery. Physicochemical and biopharmaceutical characterization of. Polyacrylamides bearing pendant sialoside groups strongly. Steric stabilizers for cubic phase lyotropic liquid crystal nanodispersions cubosomes. In contrast polyethylene glycol lipids peg2000phosphatidyl ethanolamine efficiently provide a steric barrier to the liposomes. Stabilization against droplet coalescence at submonolayer liposome coverage is consistent with charge repulsion due to the negative charges on the liposomes and the low ionic strength at.
A closer look at the structure of sterically stabilized liposomes. Steric stabilization of liposomes by phresponsive n. Encapsulation of egcg and quercetin in liposomes for. The surface characteristics of steric stabilized liposomes are determined by both the molecular mass of the peg and the amount of the peg derivatized phospholipid incorporated into the lipid bilayer. Ultrahigh nanoparticle stability against salt, ph and.
Steric stabilization of eggphosphatidylcholine liposomes by copolymers bearing short blocks of lipidmimetic units. Reduction in electrophoretic mobility but not electrostatic surface potential. The primary sites of accumulation of conventional liposomes are the tumor, liver, and spleen compared with nonliposomal formulations 1, 12, 1720. Ultrahigh nanoparticle stability against salt, ph and solvent with retained surface accessibility via depletion stabilization xu zhang, mark r. Steric stabilization of pentoxifylline liposomes also resulted in a two.
Steric stabilization of small unilamellar phospholipid vesicles liposomes following conjugation of triblock copolymer molecules by physical means can be carried out either by allowing the copolymer molecules to participate in vesicle bilayer formation, or by adsorbing the copolymers onto preformed liposome surfaces. This coating provides steric stabilization to the liposome, which is thought to limit binding of serum opsonins as well as direct interactions with cells, most importantly. The results are compared with other particulate drug carriers and. Steric stabilization is simple, requiring just the addition of a suitable polymer. Steffes materials department, chemistry and biochemistry department, university of california, santa barbara, california 93106, united states. This method employs mild conditions and is capable of efficient entrapment of a wide range of macromolecules, such as proteins. Impact of membrane fluidity on steric stabilization by lipopolymers raquel orozcoalcaraz and tonya l. Sterically stabilized liposomes incorporating the novel anticancer. Request pdf steric stabilization of ripl peptideconjugated liposomes and in vitro assessment ripl peptideconjugated liposomes pegriplls were sterically stabilized with polyethylene.
Following addition of the copolymer the effects on the size and surface charge of the liposomes were examined by dynamic light scattering and laser. Steric stabilization an overview sciencedirect topics. In other words, the polymer coating should have a thickness of around 10% of the particle diameter. Pegylation of paclitaxelloaded cationic liposomes drives steric stabilization of bicelles and vesicles thereby enhancing delivery and cytotoxicity to human cancer cells victoria m. The electrostatic repulsion can be obtained by increasing the charge of a surface by lowering the ionic strength or addition of charged molecules on the bilayer. The ability of the polymeric, polyvalent inhibitors to inhibit the binding of a polyclonal antibody to the viral surface suggests that steric stabilization may also be an. Overall, the results suggest that encapsulation of pentoxifylline in conventional liposomes enhanced its anti. The properties of the liposomes can be changed entirely. New sterically stabilized vesicles based on nonionic. Therefore, measurement of both properties, surface potential and electrophoretic mobility, of. Pegylation of paclitaxelloaded cationic liposomes drives steric stabilization of bicelles and vesicles thereby enhancing delivery and cytotoxicity to human cancer cells victoria marie steffes, zhening zhang, scott macdonald, john crowe, kai k ewert, bridget carragher, clinton s.
Liposomal, nanoparticle, and conjugated formulations of. Applications of liposomes 499 although they are composed from natural substances liposomes are no exception. We studied the effect of lipid compositions and cryoprotectants on drug entrapment efficiency, liposome size, zeta potential and longterm stability. Thus, the pharmacology and pharmacokinetics of these agents are complex and detailed studies must be done to evaluate the disposition of the encapsulated or conjugated form of the drug and the released active drug. It uses lyophilization and is scalable in both steps of. Many reports have demonstrated that the stability and ee of liposomes could be enhanced by adding an appropriate amount of tween 80 in the formulation lu et al. Ligandreceptor binding on nanoparticlestabilized liposome surfaces. Dmpc liposomes below the lcst, whereas the steric barrier was abolished above the lcst of the polymer, as it.
Request pdf steric stabilization of eggphosphatidylcholine liposomes by copolymers bearing short blocks of lipidmimetic units the ability of a number of amphiphilic di and triblock. Lipidanchored polyethylene glycol pegpe prolongs the circulation time of liposomes by steric stabilization. Sterically stabilized liposomes or in other words vesicles, ssls or ssvs came into focus since the first observations were made. Pdf controlling the physical stability of liposomal colloids.
Selective protein interactions with phosphatidylserine. The ability of a number of amphiphilic di and triblock copolymers bearing short blocks of repeating lipidmimetic units to sterically stabilize eggphosphatidylcholine epc liposomes has been studied by means of light scattering, cryogenic transmission electron microscopy cryotem, and fluorescence spectroscopy. Steric stabilization of small unilamellar phospholipid vesicles liposomes following conjugation of triblock copolymer molecules by physical means can be carried out either by allowing the. Liposomes are versatile in that the entire membrane of the liposome can be composed of either natural or manmade phospholipids. The ability of peg to increase the circulation time of the liposomes depends on both the amount of grafted peg and the length, or molecular weight of the polymer. Bioreactor droplets from liposomestabilized allaqueous. In the present study, enhancement in the antimetastatic activity of etoposide etp by encapsulation in sterically stabilized liposomes was evaluated in the murine experimental b16f10 melanoma model. The reduced mobility imparted by the surface bound peg is attributed to a mechanism similar to that described for colloidal steric stabilization. However it can be difficult to subsequently flocculate the system if this is required, the polymer can be expensive and in some cases. The sterically stabilized liposomes were stable at high calcium ion concentrations, and liposomeentrapped carboxyfluorescein was retained within the stabilized liposomes in the presence of serum for at least 5 h. Steric stabilization of ripll was successfully achieved by surface modification with peg3k, and thus peg3kripll shows potential as a nanocarrier for targeted drug delivery in. In this work, we describe the preparation and characterization of liposomes using the dehydrationrehydration process developed by gregoriadis and kirby 1984. Steric stabilization of fusogenic liposomes by a lowph.
The pharmacokinetic parameters showed that the liposomes modified by a copolymer bearing four lipidmimetic anchors exhibit superior longevity in vivo and two times lower accumulation in the liver compared to the plain liposomes and liposomes stabilized by commercial peglipid. Sterically stabilized liposomes were produced by incorporating a nonionic surfactant, polysorbate 80 tween 80, into the lipid bilayer. Electrosteric stealth rivastigmine loaded liposomes for. Steric stabilization of negatively charged liposomes by. Another method is steric stabilization achieved by covering the surface with an adsorbed layer of long, bulky molecules to prevent the close approach of the liposomes i. Preparation and evaluation of sterically stabilized. Steric stabilization of vesicles by attachment of large hydrophilic groups such as peg on the surface gives socalled stealth liposomes fig. Description of steric stabilization 289 classical and stealth liposome pharmacokinetics 301 safety of the stealth liposome administration 305.
A description of a theoretical model is presented here and evaluated with the data available. Since steric stabilization of liposomes in the biologic milieu is a necessary condition for their utility as drug carriers, significant surface modification methods. The combination of both, termed electrosteric stabilization, leads to a highly stable dispersions yadav et al. Optimizing liposomes for delivery of chemotherapeutic. The pharmacokinetic disposition of liposomal and nanoparticle agents is dependent on the carrier and not the parent drug until the drug is released from the carrier. However, their use in vivo is limited because of their rapid uptake from circulation by the reticuloendothelial system. Get a printable copy pdf file of the complete article 1. Liposomes composed of 10% of pod and 90% of a fusogenic lipid, dioleoyl phosphatidylethanolamine dope were readily prepared and remained stable for up to 12 h in neutral buffer as shown by photon correlation spectrometry and a liposome contents leakage assay. Steric stabilization of ripl peptideconjugated liposomes. Cytotoxicity analysis demonstrated that peg3kripll had a 1.
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