Direct measurement of polyethylene glycol induced depletion attraction between lipid bilayers

Tonya Kuhl, Yuqing Guo, James L. Alderfer, Alan D. Berman, Deborah E Leckband, Jacob Israelachvili, Sek Wen Hui

Research output: Contribution to journalArticle

Abstract

Although polyethylene glycol (PEG) is widely used for aggregating or fusing cells, the forces responsible for these interactions have remained elusive. Through a variety of techniques including quasi-elastic light scattering, surface force measurements, and 31P-NMR, we have established that while PEG of molecular weight 8000-10000 is effective in causing the aggregation of vesicles, PEG of lower or higher molecular weight (1000 and 18 500, respectively) is ineffective. For the first time, direct force measurements between lipid bilayers in solutions of 8000-10000 molecular weight reveal the existence of an attractive osmotic force due to a polymer depleted layer near the bilayer surface. Lower molecular weight PEG does not have a large enough size (Flory radius, RF) to generate a significant depletion force, while higher molecular weight PEG adsorbs sufficiently on the bilayer surfaces to eliminate the depletion attraction and produces a repulsive steric barrier to aggregation. The measured forces can be quantitatively described in terms of current theories of colloidal and polymer interactions. These findings suggest that the differential osmotic pressure produced by the depletion layer is responsible for vesicle aggregation and that fusion is promoted when the depletion pressure is strong enough to locally destabilize two membranes by possibly thinning them at their point of closest approach. The results provide a physicochemical basis for using PEG of certain molecular weights as fusogens for cells, liposomes, and vesicles.

Original languageEnglish (US)
Pages (from-to)3003-3014
Number of pages12
JournalLangmuir
Volume12
Issue number12
StatePublished - Jun 12 1996
Externally publishedYes

Fingerprint

Lipid bilayers
Polyethylene glycols
attraction
lipids
glycols
polyethylenes
depletion
Molecular weight
molecular weight
Agglomeration
Force measurement
Polymers
Elastic scattering
osmosis
Liposomes
Surface measurement
polymers
low molecular weights
cells
Light scattering

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics
  • Surfaces and Interfaces
  • Spectroscopy
  • Electrochemistry

Cite this

Kuhl, T., Guo, Y., Alderfer, J. L., Berman, A. D., Leckband, D. E., Israelachvili, J., & Hui, S. W. (1996). Direct measurement of polyethylene glycol induced depletion attraction between lipid bilayers. Langmuir, 12(12), 3003-3014.

Direct measurement of polyethylene glycol induced depletion attraction between lipid bilayers. / Kuhl, Tonya; Guo, Yuqing; Alderfer, James L.; Berman, Alan D.; Leckband, Deborah E; Israelachvili, Jacob; Hui, Sek Wen.

In: Langmuir, Vol. 12, No. 12, 12.06.1996, p. 3003-3014.

Research output: Contribution to journalArticle

Kuhl, T, Guo, Y, Alderfer, JL, Berman, AD, Leckband, DE, Israelachvili, J & Hui, SW 1996, 'Direct measurement of polyethylene glycol induced depletion attraction between lipid bilayers', Langmuir, vol. 12, no. 12, pp. 3003-3014.
Kuhl T, Guo Y, Alderfer JL, Berman AD, Leckband DE, Israelachvili J et al. Direct measurement of polyethylene glycol induced depletion attraction between lipid bilayers. Langmuir. 1996 Jun 12;12(12):3003-3014.
Kuhl, Tonya ; Guo, Yuqing ; Alderfer, James L. ; Berman, Alan D. ; Leckband, Deborah E ; Israelachvili, Jacob ; Hui, Sek Wen. / Direct measurement of polyethylene glycol induced depletion attraction between lipid bilayers. In: Langmuir. 1996 ; Vol. 12, No. 12. pp. 3003-3014.
@article{0d5c94caa2074f7f808c89765126e827,
title = "Direct measurement of polyethylene glycol induced depletion attraction between lipid bilayers",
abstract = "Although polyethylene glycol (PEG) is widely used for aggregating or fusing cells, the forces responsible for these interactions have remained elusive. Through a variety of techniques including quasi-elastic light scattering, surface force measurements, and 31P-NMR, we have established that while PEG of molecular weight 8000-10000 is effective in causing the aggregation of vesicles, PEG of lower or higher molecular weight (1000 and 18 500, respectively) is ineffective. For the first time, direct force measurements between lipid bilayers in solutions of 8000-10000 molecular weight reveal the existence of an attractive osmotic force due to a polymer depleted layer near the bilayer surface. Lower molecular weight PEG does not have a large enough size (Flory radius, RF) to generate a significant depletion force, while higher molecular weight PEG adsorbs sufficiently on the bilayer surfaces to eliminate the depletion attraction and produces a repulsive steric barrier to aggregation. The measured forces can be quantitatively described in terms of current theories of colloidal and polymer interactions. These findings suggest that the differential osmotic pressure produced by the depletion layer is responsible for vesicle aggregation and that fusion is promoted when the depletion pressure is strong enough to locally destabilize two membranes by possibly thinning them at their point of closest approach. The results provide a physicochemical basis for using PEG of certain molecular weights as fusogens for cells, liposomes, and vesicles.",
author = "Tonya Kuhl and Yuqing Guo and Alderfer, {James L.} and Berman, {Alan D.} and Leckband, {Deborah E} and Jacob Israelachvili and Hui, {Sek Wen}",
year = "1996",
month = "6",
day = "12",
language = "English (US)",
volume = "12",
pages = "3003--3014",
journal = "Langmuir",
issn = "0743-7463",
publisher = "American Chemical Society",
number = "12",

}

TY - JOUR

T1 - Direct measurement of polyethylene glycol induced depletion attraction between lipid bilayers

AU - Kuhl, Tonya

AU - Guo, Yuqing

AU - Alderfer, James L.

AU - Berman, Alan D.

AU - Leckband, Deborah E

AU - Israelachvili, Jacob

AU - Hui, Sek Wen

PY - 1996/6/12

Y1 - 1996/6/12

N2 - Although polyethylene glycol (PEG) is widely used for aggregating or fusing cells, the forces responsible for these interactions have remained elusive. Through a variety of techniques including quasi-elastic light scattering, surface force measurements, and 31P-NMR, we have established that while PEG of molecular weight 8000-10000 is effective in causing the aggregation of vesicles, PEG of lower or higher molecular weight (1000 and 18 500, respectively) is ineffective. For the first time, direct force measurements between lipid bilayers in solutions of 8000-10000 molecular weight reveal the existence of an attractive osmotic force due to a polymer depleted layer near the bilayer surface. Lower molecular weight PEG does not have a large enough size (Flory radius, RF) to generate a significant depletion force, while higher molecular weight PEG adsorbs sufficiently on the bilayer surfaces to eliminate the depletion attraction and produces a repulsive steric barrier to aggregation. The measured forces can be quantitatively described in terms of current theories of colloidal and polymer interactions. These findings suggest that the differential osmotic pressure produced by the depletion layer is responsible for vesicle aggregation and that fusion is promoted when the depletion pressure is strong enough to locally destabilize two membranes by possibly thinning them at their point of closest approach. The results provide a physicochemical basis for using PEG of certain molecular weights as fusogens for cells, liposomes, and vesicles.

AB - Although polyethylene glycol (PEG) is widely used for aggregating or fusing cells, the forces responsible for these interactions have remained elusive. Through a variety of techniques including quasi-elastic light scattering, surface force measurements, and 31P-NMR, we have established that while PEG of molecular weight 8000-10000 is effective in causing the aggregation of vesicles, PEG of lower or higher molecular weight (1000 and 18 500, respectively) is ineffective. For the first time, direct force measurements between lipid bilayers in solutions of 8000-10000 molecular weight reveal the existence of an attractive osmotic force due to a polymer depleted layer near the bilayer surface. Lower molecular weight PEG does not have a large enough size (Flory radius, RF) to generate a significant depletion force, while higher molecular weight PEG adsorbs sufficiently on the bilayer surfaces to eliminate the depletion attraction and produces a repulsive steric barrier to aggregation. The measured forces can be quantitatively described in terms of current theories of colloidal and polymer interactions. These findings suggest that the differential osmotic pressure produced by the depletion layer is responsible for vesicle aggregation and that fusion is promoted when the depletion pressure is strong enough to locally destabilize two membranes by possibly thinning them at their point of closest approach. The results provide a physicochemical basis for using PEG of certain molecular weights as fusogens for cells, liposomes, and vesicles.

UR - http://www.scopus.com/inward/record.url?scp=0001733884&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0001733884&partnerID=8YFLogxK

M3 - Article

AN - SCOPUS:0001733884

VL - 12

SP - 3003

EP - 3014

JO - Langmuir

JF - Langmuir

SN - 0743-7463

IS - 12

ER -