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, Robert K. Prud'homme

Research output: Contribution to journalArticle

19 Scopus citations

Abstract

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 to immune recognition. Previously, three comb-graft polymers (HMPEG136-DP3, HMPEG273-DP2.5, and HMPEG273-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 mN/m. This threshold correlates with a 92% decrease in complement protein binding for liposomes coated with 1 mg/m2 HMPEG273-DP5. This may suggest that surface viscous forces play a role in reducing complement protein binding.

Original languageEnglish (US)
Pages (from-to)4056-4064
Number of pages9
JournalLangmuir
Volume24
Issue number8
DOIs
StatePublished - Apr 15 2008

All Science Journal Classification (ASJC) codes

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

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