Direct Measurement of Polyethylene Glycol Induced Depletion Attraction between Lipid Bilayers

• DOI: 10.1021/la950802l
• Publication Date: 2002-07-26T05:00:18Z
• Authors: Tonya Kuhl; Yuqing Guo; James L. Alderfer; Alan D. Berman; Deborah Leckband; Jacob Israelachvili; Sek Wen Hui
• Keywords: Osmotic pressure

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