期刊
JOURNAL OF COLLOID AND INTERFACE SCIENCE
卷 478, 期 -, 页码 353-364出版社
ACADEMIC PRESS INC ELSEVIER SCIENCE
DOI: 10.1016/j.jcis.2016.06.016
关键词
Dipalmitoylphosphatidylcholine (DPPC); Monolayers; Cations; Marine aerosols; Langmuir isotherms; Brewster angle microscopy (BAM); Infrared reflection-absorption spectroscopy (IRRAS)
资金
- National Science Foundation, United States
- Center for Aerosol Impacts on Climate and Environment [CHE1305427]
The effect of highly concentrated salt solutions of marine-relevant cations (Na+, K+, Mg2+, and Ca2+) on Langmuir monolayers of dipalmitoylphosphatidylcholine (DPPC) was investigated by means of surface pressure-area isotherms, Brewster angle microscopy (BAM), and infrared reflection-absorption spectroscopy (IRRAS). It was found that monovalent cations and Mg2+ have similar phase behavior, causing DPPC monolayers to expand, while Ca2+ induces condensation. All cations disrupted the surface morphology at high cation concentration, resulting in decreased reflectivity from the monolayer. Monolayer refractive index was calculated from BAM image intensity in the liquid condensed phase and decreased with increasing cation concentration, which suggests that orientation of the alkyl chains change. Monovalent ions increase ordering of the allcyl chains, more than divalents, yet have little interaction with the DPPC headgroup. Mg2+ induces gauche defects in the alkyl chain and increases headgroup hydration at low lipid coverage but increases chain ordering and dehydrates the headgroup at high lipid coverage. Ca2+ orders alkyl chains and dehydrates the phosphate moiety, independent of lipid phase. At the highest salt concentration investigated, significant narrowing of the asymmetric PO2- vibrational mode occurs and is attributed to considerable dehydration of the DPPC headgroup. (C) 2016 Elsevier Inc. All rights reserved.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据