Skip to main content
PMC home page
Biophysical Journal logoLink to Biophysical Journal
. 1995 May;68(5):1903–1920. doi: 10.1016/S0006-3495(95)80368-1

Structure and phase behavior of lipid suspensions containing phospholipids with covalently attached poly(ethylene glycol).

A K Kenworthy 1, S A Simon 1, T J McIntosh 1
PMCID: PMC1282094  PMID: 7612833

Abstract

Liposomes containing phospholipids with covalently attached poly(ethylene glycol) (PEG-lipids) are being developed for in vivo drug delivery. In this paper we determine the structure and phase behavior of fully hydrated distearoylphosphatidylcholine (DSPC) suspensions containing PEG-lipids composed of distearoylphosphatidylethanolamine with attached PEGs of molecular weights ranging from 350 to 5000. For DSPC:PEG-lipid suspensions containing 0-60 mol % PEG-lipid, differential scanning calorimetry shows main endothermic transitions ranging from 55 to 64 degrees C, depending on the size of the PEG and concentration of PEG-lipid. The enthalpy of this main transition remains constant for all PEG-350 concentrations but decreases with increasing amounts of PEG-750, PEG-2000, or PEG-5000, ultimately disappearing at PEG-lipid concentrations greater than about 60 mol %. Low-angle and wide-angle x-ray diffraction show that tilted gel (L beta') phase bilayers are formed for all PEG-lipid molecular weights at concentrations of about 10 mol % or less, with the distance between bilayers depending on PEG molecular weight and PEG-lipid concentration. At PEG-lipid concentrations greater than 10 mol %, the lipid structure depends on the size of the PEG moiety. X-ray diffraction analysis shows that untilted interdigitated (L beta I) gel phase bilayers form with the incorporation of 40-100 mol % PEG-350 or 20-70 mol % PEG-750, and untilted gel (L beta) phase bilayers are formed in the presence of about 20-60 mol % PEG-2000 and PEG-5000. Light microscopy, turbidity measurements, x-ray diffraction, and 1H-NMR indicate that a pure micellar phase forms in the presence of greater than about 60% PEG-750, PEG-2000, or PEG-5000.

Full text

PDF
1903

Selected References

These references are in PubMed. This may not be the complete list of references from this article.

  1. Ahmad I., Longenecker M., Samuel J., Allen T. M. Antibody-targeted delivery of doxorubicin entrapped in sterically stabilized liposomes can eradicate lung cancer in mice. Cancer Res. 1993 Apr 1;53(7):1484–1488. [PubMed] [Google Scholar]
  2. Allen T. M., Hansen C., Martin F., Redemann C., Yau-Young A. Liposomes containing synthetic lipid derivatives of poly(ethylene glycol) show prolonged circulation half-lives in vivo. Biochim Biophys Acta. 1991 Jul 1;1066(1):29–36. doi: 10.1016/0005-2736(91)90246-5. [DOI] [PubMed] [Google Scholar]
  3. Almog S., Litman B. J., Wimley W., Cohen J., Wachtel E. J., Barenholz Y., Ben-Shaul A., Lichtenberg D. States of aggregation and phase transformations in mixtures of phosphatidylcholine and octyl glucoside. Biochemistry. 1990 May 15;29(19):4582–4592. doi: 10.1021/bi00471a012. [DOI] [PubMed] [Google Scholar]
  4. Blaurock A. E., Worthington C. R. Treatment of low angle x-ray data from planar and concentric multilayered structures. Biophys J. 1966 May;6(3):305–312. doi: 10.1016/S0006-3495(66)86658-4. [DOI] [PMC free article] [PubMed] [Google Scholar]
  5. Blume G., Cevc G., Crommelin M. D., Bakker-Woudenberg I. A., Kluft C., Storm G. Specific targeting with poly(ethylene glycol)-modified liposomes: coupling of homing devices to the ends of the polymeric chains combines effective target binding with long circulation times. Biochim Biophys Acta. 1993 Jun 18;1149(1):180–184. doi: 10.1016/0005-2736(93)90039-3. [DOI] [PubMed] [Google Scholar]
  6. Blume G., Cevc G. Liposomes for the sustained drug release in vivo. Biochim Biophys Acta. 1990 Nov 2;1029(1):91–97. doi: 10.1016/0005-2736(90)90440-y. [DOI] [PubMed] [Google Scholar]
  7. Blume G., Cevc G. Molecular mechanism of the lipid vesicle longevity in vivo. Biochim Biophys Acta. 1993 Mar 14;1146(2):157–168. doi: 10.1016/0005-2736(93)90351-y. [DOI] [PubMed] [Google Scholar]
  8. Bourgès M., Small D. M., Dervichian D. G. Biophysics of lipidic associations. II. The ternary systems: cholesterol-lecithin-water. Biochim Biophys Acta. 1967 Feb 14;137(1):157–167. doi: 10.1016/0005-2760(67)90019-7. [DOI] [PubMed] [Google Scholar]
  9. Bridgett M. J., Davies M. C., Denyer S. P. Control of staphylococcal adhesion to polystyrene surfaces by polymer surface modification with surfactants. Biomaterials. 1992;13(7):411–416. doi: 10.1016/0142-9612(92)90159-l. [DOI] [PubMed] [Google Scholar]
  10. Carmona-Ribeiro A. M., Chaimovich H. Salt-induced aggregation and fusion of dioctadecyldimethylammonium chloride and sodium dihexadecylphosphate vesicles. Biophys J. 1986 Oct;50(4):621–628. doi: 10.1016/S0006-3495(86)83501-9. [DOI] [PMC free article] [PubMed] [Google Scholar]
  11. Cevc G. How membrane chain melting properties are regulated by the polar surface of the lipid bilayer. Biochemistry. 1987 Oct 6;26(20):6305–6310. doi: 10.1021/bi00394a002. [DOI] [PubMed] [Google Scholar]
  12. Desai N. P., Hossainy S. F., Hubbell J. A. Surface-immobilized polyethylene oxide for bacterial repellence. Biomaterials. 1992;13(7):417–420. doi: 10.1016/0142-9612(92)90160-p. [DOI] [PubMed] [Google Scholar]
  13. Finer E. G., Flook A. G., Hauser H. Mechanism of sonication of aqueous egg yolk lecithin dispersions and nature of the resultant particles. Biochim Biophys Acta. 1972 Jan 27;260(1):49–58. doi: 10.1016/0005-2760(72)90073-2. [DOI] [PubMed] [Google Scholar]
  14. Herbette L., Marquardt J., Scarpa A., Blasie J. K. A direct analysis of lamellar x-ray diffraction from hydrated oriented multilayers of fully functional sarcoplasmic reticulum. Biophys J. 1977 Nov;20(2):245–272. doi: 10.1016/S0006-3495(77)85547-1. [DOI] [PMC free article] [PubMed] [Google Scholar]
  15. Hinz H. J., Sturtevant J. M. Calorimetric studies of dilute aqueous suspensions of bilayers formed from synthetic L- -lecithins. J Biol Chem. 1972 Oct 10;247(19):6071–6075. [PubMed] [Google Scholar]
  16. Hitchcock P. B., Mason R., Thomas K. M., Shipley G. G. Structural chemistry of 1,2 dilauroyl-DL-phosphatidylethanolamine: molecular conformation and intermolecular packing of phospholipids. Proc Natl Acad Sci U S A. 1974 Aug;71(8):3036–3040. doi: 10.1073/pnas.71.8.3036. [DOI] [PMC free article] [PubMed] [Google Scholar]
  17. Israelachvili J. N., Marcelja S., Horn R. G. Physical principles of membrane organization. Q Rev Biophys. 1980 May;13(2):121–200. doi: 10.1017/s0033583500001645. [DOI] [PubMed] [Google Scholar]
  18. Israelachvili J. N., Mitchell D. J., Ninham B. W. Theory of self-assembly of lipid bilayers and vesicles. Biochim Biophys Acta. 1977 Oct 17;470(2):185–201. doi: 10.1016/0005-2736(77)90099-2. [DOI] [PubMed] [Google Scholar]
  19. Janiak M. J., Small D. M., Shipley G. G. Temperature and compositional dependence of the structure of hydrated dimyristoyl lecithin. J Biol Chem. 1979 Jul 10;254(13):6068–6078. [PubMed] [Google Scholar]
  20. Klibanov A. L., Maruyama K., Torchilin V. P., Huang L. Amphipathic polyethyleneglycols effectively prolong the circulation time of liposomes. FEBS Lett. 1990 Jul 30;268(1):235–237. doi: 10.1016/0014-5793(90)81016-h. [DOI] [PubMed] [Google Scholar]
  21. Kuhl T. L., Leckband D. E., Lasic D. D., Israelachvili J. N. Modulation of interaction forces between bilayers exposing short-chained ethylene oxide headgroups. Biophys J. 1994 May;66(5):1479–1488. doi: 10.1016/S0006-3495(94)80938-5. [DOI] [PMC free article] [PubMed] [Google Scholar]
  22. Lasic D. D., Martin F. J., Gabizon A., Huang S. K., Papahadjopoulos D. Sterically stabilized liposomes: a hypothesis on the molecular origin of the extended circulation times. Biochim Biophys Acta. 1991 Nov 18;1070(1):187–192. doi: 10.1016/0005-2736(91)90162-2. [DOI] [PubMed] [Google Scholar]
  23. LeNeveu D. M., Rand R. P. Measurement and modification of forces between lecithin bilayers. Biophys J. 1977 May;18(2):209–230. doi: 10.1016/S0006-3495(77)85608-7. [DOI] [PMC free article] [PubMed] [Google Scholar]
  24. Lee J. H., Kopecek J., Andrade J. D. Protein-resistant surfaces prepared by PEO-containing block copolymer surfactants. J Biomed Mater Res. 1989 Mar;23(3):351–368. doi: 10.1002/jbm.820230306. [DOI] [PubMed] [Google Scholar]
  25. Lesslauer W., Cain J. E., Blasie J. K. X-ray diffraction studies of lecithin bimolecular leaflets with incorporated fluorescent probes. Proc Natl Acad Sci U S A. 1972 Jun;69(6):1499–1503. doi: 10.1073/pnas.69.6.1499. [DOI] [PMC free article] [PubMed] [Google Scholar]
  26. Mabrey S., Sturtevant J. M. Investigation of phase transitions of lipids and lipid mixtures by sensitivity differential scanning calorimetry. Proc Natl Acad Sci U S A. 1976 Nov;73(11):3862–3866. doi: 10.1073/pnas.73.11.3862. [DOI] [PMC free article] [PubMed] [Google Scholar]
  27. Mason J. T., Huang C., Biltonen R. L. Calorimetric investigations of saturated mixed-chain phosphatidylcholine bilayer dispersions. Biochemistry. 1981 Oct 13;20(21):6086–6092. doi: 10.1021/bi00524a026. [DOI] [PubMed] [Google Scholar]
  28. Mayhew E. G., Lasic D., Babbar S., Martin F. J. Pharmacokinetics and antitumor activity of epirubicin encapsulated in long-circulating liposomes incorporating a polyethylene glycol-derivatized phospholipid. Int J Cancer. 1992 May 8;51(2):302–309. doi: 10.1002/ijc.2910510221. [DOI] [PubMed] [Google Scholar]
  29. McDaniel R. V., McIntosh T. J. X-Ray Diffraction Studies of the Cholera Toxin receptor, G(M1). Biophys J. 1986 Jan;49(1):94–96. doi: 10.1016/s0006-3495(86)83606-2. [DOI] [PMC free article] [PubMed] [Google Scholar]
  30. McIntosh T. J. Differences in hydrocarbon chain tilt between hydrated phosphatidylethanolamine and phosphatidylcholine bilayers. A molecular packing model. Biophys J. 1980 Feb;29(2):237–245. doi: 10.1016/S0006-3495(80)85128-9. [DOI] [PMC free article] [PubMed] [Google Scholar]
  31. McIntosh T. J., Holloway P. W. Determination of the depth of bromine atoms in bilayers formed from bromolipid probes. Biochemistry. 1987 Mar 24;26(6):1783–1788. doi: 10.1021/bi00380a042. [DOI] [PubMed] [Google Scholar]
  32. McIntosh T. J., Magid A. D., Simon S. A. Cholesterol modifies the short-range repulsive interactions between phosphatidylcholine membranes. Biochemistry. 1989 Jan 10;28(1):17–25. doi: 10.1021/bi00427a004. [DOI] [PubMed] [Google Scholar]
  33. McIntosh T. J., Magid A. D., Simon S. A. Range of the solvation pressure between lipid membranes: dependence on the packing density of solvent molecules. Biochemistry. 1989 Sep 19;28(19):7904–7912. doi: 10.1021/bi00445a053. [DOI] [PubMed] [Google Scholar]
  34. McIntosh T. J., Magid A. D., Simon S. A. Steric repulsion between phosphatidylcholine bilayers. Biochemistry. 1987 Nov 17;26(23):7325–7332. doi: 10.1021/bi00397a020. [DOI] [PubMed] [Google Scholar]
  35. McIntosh T. J., Simon S. A. Hydration force and bilayer deformation: a reevaluation. Biochemistry. 1986 Jul 15;25(14):4058–4066. doi: 10.1021/bi00362a011. [DOI] [PubMed] [Google Scholar]
  36. McIntosh T. J., Simon S. A., Needham D., Huang C. H. Interbilayer interactions between sphingomyelin and sphingomyelin/cholesterol bilayers. Biochemistry. 1992 Feb 25;31(7):2020–2024. doi: 10.1021/bi00122a018. [DOI] [PubMed] [Google Scholar]
  37. Milner S. T. Polymer brushes. Science. 1991 Feb 22;251(4996):905–914. doi: 10.1126/science.251.4996.905. [DOI] [PubMed] [Google Scholar]
  38. Mori A., Klibanov A. L., Torchilin V. P., Huang L. Influence of the steric barrier activity of amphipathic poly(ethyleneglycol) and ganglioside GM1 on the circulation time of liposomes and on the target binding of immunoliposomes in vivo. FEBS Lett. 1991 Jun 24;284(2):263–266. doi: 10.1016/0014-5793(91)80699-4. [DOI] [PubMed] [Google Scholar]
  39. Needham D., McIntosh T. J., Lasic D. D. Repulsive interactions and mechanical stability of polymer-grafted lipid membranes. Biochim Biophys Acta. 1992 Jul 8;1108(1):40–48. doi: 10.1016/0005-2736(92)90112-y. [DOI] [PubMed] [Google Scholar]
  41. Papahadjopoulos D., Allen T. M., Gabizon A., Mayhew E., Matthay K., Huang S. K., Lee K. D., Woodle M. C., Lasic D. D., Redemann C. Sterically stabilized liposomes: improvements in pharmacokinetics and antitumor therapeutic efficacy. Proc Natl Acad Sci U S A. 1991 Dec 15;88(24):11460–11464. doi: 10.1073/pnas.88.24.11460. [DOI] [PMC free article] [PubMed] [Google Scholar]
  42. Parsegian V. A., Rand R. P., Fuller N. L., Rau D. C. Osmotic stress for the direct measurement of intermolecular forces. Methods Enzymol. 1986;127:400–416. doi: 10.1016/0076-6879(86)27032-9. [DOI] [PubMed] [Google Scholar]
  43. Pearson R. H., Pascher I. The molecular structure of lecithin dihydrate. Nature. 1979 Oct 11;281(5731):499–501. doi: 10.1038/281499a0. [DOI] [PubMed] [Google Scholar]
  44. Ranck J. L., Keira T., Luzzati V. A novel packing of the hydrocarbon chains in lipids. The low temperature phases of dipalmitoyl phosphatidyl-glycerol. Biochim Biophys Acta. 1977 Sep 28;488(3):432–441. doi: 10.1016/0005-2760(77)90201-6. [DOI] [PubMed] [Google Scholar]
  45. Ribeiro A. A., Dennis E. A. Proton magnetic resonance relaxation studies on the structure of mixed micelles of Triton X-100 and dimyristoylphosphatidylcholine. Biochemistry. 1975 Aug 26;14(17):3746–3755. doi: 10.1021/bi00688a005. [DOI] [PubMed] [Google Scholar]
  46. Rowe E. S. Induction of lateral phase separations in binary lipid mixtures by alcohol. Biochemistry. 1987 Jan 13;26(1):46–51. doi: 10.1021/bi00375a007. [DOI] [PubMed] [Google Scholar]
  47. Simon S. A., McIntosh T. J. Interdigitated hydrocarbon chain packing causes the biphasic transition behavior in lipid/alcohol suspensions. Biochim Biophys Acta. 1984 Jun 13;773(1):169–172. doi: 10.1016/0005-2736(84)90562-5. [DOI] [PubMed] [Google Scholar]
  48. Simon S. A., McIntosh T. J., Latorre R. Influence of cholesterol on water penetration into bilayers. Science. 1982 Apr 2;216(4541):65–67. doi: 10.1126/science.7063872. [DOI] [PubMed] [Google Scholar]
  49. Sparling M. L., Zidovetzki R., Muller L., Chan S. I. Analysis of membrane lipids by 500 MHz 1H NMR. Anal Biochem. 1989 Apr;178(1):67–76. doi: 10.1016/0003-2697(89)90358-8. [DOI] [PubMed] [Google Scholar]
  50. Swamy M. J., Angerstein B., Marsh D. Differential scanning calorimetry of thermotropic phase transitions in vitaminylated lipids: aqueous dispersions of N-biotinyl phosphatidylethanolamines. Biophys J. 1994 Jan;66(1):31–39. doi: 10.1016/S0006-3495(94)80761-1. [DOI] [PMC free article] [PubMed] [Google Scholar]
  51. Tardieu A., Luzzati V., Reman F. C. Structure and polymorphism of the hydrocarbon chains of lipids: a study of lecithin-water phases. J Mol Biol. 1973 Apr 25;75(4):711–733. doi: 10.1016/0022-2836(73)90303-3. [DOI] [PubMed] [Google Scholar]
  52. Torchilin V. P., Klibanov A. L., Huang L., O'Donnell S., Nossiff N. D., Khaw B. A. Targeted accumulation of polyethylene glycol-coated immunoliposomes in infarcted rabbit myocardium. FASEB J. 1992 Jun;6(9):2716–2719. doi: 10.1096/fasebj.6.9.1612296. [DOI] [PubMed] [Google Scholar]
  53. Tristram-Nagle S., Suter R. M., Sun W. J., Nagle J. F. Kinetics of subgel formation in DPPC: X-ray diffraction proves nucleation-growth hypothesis. Biochim Biophys Acta. 1994 Apr 20;1191(1):14–20. doi: 10.1016/0005-2736(94)90227-5. [DOI] [PubMed] [Google Scholar]
  54. Vaage J., Donovan D., Mayhew E., Uster P., Woodle M. Therapy of mouse mammary carcinomas with vincristine and doxorubicin encapsulated in sterically stabilized liposomes. Int J Cancer. 1993 Jul 30;54(6):959–964. doi: 10.1002/ijc.2910540616. [DOI] [PubMed] [Google Scholar]
  55. Walter A., Vinson P. K., Kaplun A., Talmon Y. Intermediate structures in the cholate-phosphatidylcholine vesicle-micelle transition. Biophys J. 1991 Dec;60(6):1315–1325. doi: 10.1016/S0006-3495(91)82169-5. [DOI] [PMC free article] [PubMed] [Google Scholar]
  56. Wiener M. C., Suter R. M., Nagle J. F. Structure of the fully hydrated gel phase of dipalmitoylphosphatidylcholine. Biophys J. 1989 Feb;55(2):315–325. doi: 10.1016/S0006-3495(89)82807-3. [DOI] [PMC free article] [PubMed] [Google Scholar]
  57. Williams S. S., Alosco T. R., Mayhew E., Lasic D. D., Martin F. J., Bankert R. B. Arrest of human lung tumor xenograft growth in severe combined immunodeficient mice using doxorubicin encapsulated in sterically stabilized liposomes. Cancer Res. 1993 Sep 1;53(17):3964–3967. [PubMed] [Google Scholar]
  58. Woodle M. C., Lasic D. D. Sterically stabilized liposomes. Biochim Biophys Acta. 1992 Aug 14;1113(2):171–199. doi: 10.1016/0304-4157(92)90038-c. [DOI] [PubMed] [Google Scholar]
  59. Woodle M. C., Matthay K. K., Newman M. S., Hidayat J. E., Collins L. R., Redemann C., Martin F. J., Papahadjopoulos D. Versatility in lipid compositions showing prolonged circulation with sterically stabilized liposomes. Biochim Biophys Acta. 1992 Apr 13;1105(2):193–200. doi: 10.1016/0005-2736(92)90194-q. [DOI] [PubMed] [Google Scholar]
  60. Worcester D. L., Franks N. P. Structural analysis of hydrated egg lecithin and cholesterol bilayers. II. Neutrol diffraction. J Mol Biol. 1976 Jan 25;100(3):359–378. doi: 10.1016/s0022-2836(76)80068-x. [DOI] [PubMed] [Google Scholar]
  61. Worthington C. R., King G. I., McIntosh T. J. Direct structure determination of multilayered membrane-type systems which contain fluid layers. Biophys J. 1973 May;13(5):480–494. doi: 10.1016/S0006-3495(73)86001-1. [DOI] [PMC free article] [PubMed] [Google Scholar]
  62. Worthington C. R. The interpretation of low-angle X-ray data from planar and concentric multilayered structures. The use of one-dimensional electron density strip models. Biophys J. 1969 Feb;9(2):222–234. doi: 10.1016/S0006-3495(69)86381-2. [DOI] [PMC free article] [PubMed] [Google Scholar]
  63. Wu N. Z., Da D., Rudoll T. L., Needham D., Whorton A. R., Dewhirst M. W. Increased microvascular permeability contributes to preferential accumulation of Stealth liposomes in tumor tissue. Cancer Res. 1993 Aug 15;53(16):3765–3770. [PubMed] [Google Scholar]

Articles from Biophysical Journal are provided here courtesy of The Biophysical Society

RESOURCES