Polycation Interactions with Zwitterionic Phospholipid Monolayers on Oil Nanodroplet Suspensions in Water (D2O) Probed by Sum Frequency Scattering

Laura L. Olenick, Julianne M. Troiano, Nikolay Smolentsev, Paul E. Ohno, Sylvie Roke*, Franz M. Geiger

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

8 Scopus citations

Abstract

By combining dynamic light scattering (DLS) measurements with the interface and bond specificity of vibrational sum frequency generation scattering (SFS) spectroscopy, we probe several structural aspects of how zwitterionic DMPC lipids adsorbed to oil droplets suspended in water (D2O) respond to the presence of the common polycation poly(allylamine hydrochloride) (PAH) in the presence of low and high salt concentration. We show that the polycation interactions with the lipids generally result in two distinct outcomes that depend upon salt and PAH concentration, identified here as Scheme 1 (observed under conditions of high salt concentration) and Scheme 2 (observed under conditions of low salt concentration). The schemes differ in the extent of changes to droplet size and droplet coalescence coinciding with PAH addition. Our combined DLS and SFS results illustrate that cationic polymers do not always interact in the same fashion with lipid membranes and demonstrate the feasibility of second-order spectroscopic methods to probe those interactions with chemical bond specificity, not only for the alkyl tails (C-H stretches) but also for the choline headgroup (P-O stretches).

Original languageEnglish (US)
Pages (from-to)5049-5056
Number of pages8
JournalJournal of Physical Chemistry B
Volume122
Issue number19
DOIs
StatePublished - May 17 2018

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films
  • Materials Chemistry

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