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Surface Rheology of Hydrophobically Modified PEG Polymers Associating with a Phospholipid Monolayer at the Air-Water
 

Summary: Surface Rheology of Hydrophobically Modified PEG Polymers
Associating with a Phospholipid Monolayer at the Air-Water
Interface
Debra T. Auguste, John Kirkwood, Joachim Kohn, Gerald G. Fuller, and
Robert K. Prud'homme*,|
School of Engineering and Applied Sciences, HarVard UniVersity, Cambridge, Massachusetts 02139,
Department of Chemical Engineering, Stanford UniVersity, Stanford, California 94305, Department of
Chemistry, Rutgers UniVersity, Piscataway, New Jersey 08854, and Department of Chemical Engineering,
Princeton UniVersity, Engineering Quadrangle, Princeton, New Jersey 08544
ReceiVed October 4, 2007. In Final Form: January 16, 2008
Surface rheology of irreversibly bound hydrophobically modified poly(ethylene glycol) (PEG) polymers (HMPEG)
on a dipalmitoylphosphatidylcholine (DPPC) monolayer is investigated to determine attributes that may contribute
toimmunerecognition.Previously,threecomb-graftpolymers(HMPEG136-DP3,HMPEG273-DP2.5,andHMPEG273-
DP5) adsorbed on liposomes were examined for their strength of adsorption and protection from complement binding.
The data supported an optimal ratio between the hydrophilicity of the PEG polymer and the number of hydrophobic
anchors. The HMPEG polymers have different polymer brush thicknesses (4.2-5.9 nm) and levels of cooperativity
(2.5-5 hydrophobes). The results indicate that an increased viscous force (above 0.25 mN s/m) at the surface may
enable the polymers to shield liposomes from protein interactions. Similar rheological behavior is shown for all
polymer architectures at low polymer surface coverage (0.5 mg/m2, in the mushroom regime), whereas at high surface
coverage (>0.5 mg/m2, in the brush regime), we observe a structural dependence of the surface viscous forces at 40

  

Source: Auguste, Debra T. - School of Engineering and Applied Sciences, Harvard University

 

Collections: Materials Science; Biology and Medicine