Jump to main content
Jump to site search

Issue 47, 2016
Previous Article Next Article

Surface organization of a DPPC monolayer on concentrated SrCl2 and ZnCl2 solutions

Author affiliations

Abstract

Transition metals are known to be enriched in organic-coated marine aerosols, but the impact these cations have on their surface properties is not well understood. Here the effect of Zn2+ enrichment on the surface properties of a dipalmitoylphosphatidylcholine (DPPC) monolayer was investigated and compared to that of the alkaline earth metal Sr2+, an ion not enriched in aerosols. Phase behavior of the DPPC film on concentrated aqueous solutions was probed with surface pressure–area isotherms while domain morphology was monitored with Brewster angle microscopy (BAM). Infrared reflection–absorption spectroscopy (IRRAS) and vibrational sum frequency generation (VSFG) spectroscopy were used to assess the impact of cations on the conformation and orientation of alkyl chains as well as the hydration state of the carbonyl and phosphatidylcholine (PC) moieties. Results of compression isotherms and BAM show that Zn2+ strongly interacts with DPPC molecules, and induces condensation of the monolayer while Sr2+ only weakly interacts with the monolayer in expanded phases. Conformational order and orientation of alkyl chains in the condensed phase are not significantly altered by either cation. IRRAS indicates that Sr2+ has weak interactions with the PC headgroup. Zn2+ ions cause dehydration of carbonyl groups and binds to the phosphate group in a 2 : 1 bridging complex. Findings here suggest that Sr2+ is not enriched in aerosols because it behaves similar to a monovalent ion and only weakly interacts with the monolayer, while enrichment of Zn2+ is due to strong binding to the lipid film.

Graphical abstract: Surface organization of a DPPC monolayer on concentrated SrCl2 and ZnCl2 solutions

Back to tab navigation
Please wait while Download options loads

Supplementary files

Publication details

The article was received on 07 Oct 2016, accepted on 09 Nov 2016, published on 17 Nov 2016 and first published online on 17 Nov 2016


Article type: Paper
DOI: 10.1039/C6CP06887A
Citation: Phys. Chem. Chem. Phys., 2016,18, 32345-32357
  •   Request permissions

    Surface organization of a DPPC monolayer on concentrated SrCl2 and ZnCl2 solutions

    E. M. Adams, D. Verreault, T. Jayarathne, R. E. Cochran, E. A. Stone and H. C. Allen, Phys. Chem. Chem. Phys., 2016, 18, 32345
    DOI: 10.1039/C6CP06887A

Search articles by author