AFM study of lipid monolayers. 1. Pressure-induced phase behavior of single and mixed fatty acids
(1999) In Langmuir 15(20). p.6946-6949- Abstract
Monolayers of palmitic (C16:0) and lignoceric acid (C24:0) and their equimolar mixture were transferred to a hydrophilic mica substrate at various surface pressures and investigated by means of atomic force microscopy (AFM) in contact and lateral force modes. The first-order transition of lignoceric acid gives a plateau region, representing a liquid expanded to liquid condensed phase transition in the pressure-area isotherm. This was visualized by AFM as stripes of a condensed phase within the expanded phase, exhibiting a small height difference but a significant difference in friction. The corresponding phase transition of the palmitic acid was continuous, and no changes of the Langmuir-Blodgett films with respect to pressure were... (More)
Monolayers of palmitic (C16:0) and lignoceric acid (C24:0) and their equimolar mixture were transferred to a hydrophilic mica substrate at various surface pressures and investigated by means of atomic force microscopy (AFM) in contact and lateral force modes. The first-order transition of lignoceric acid gives a plateau region, representing a liquid expanded to liquid condensed phase transition in the pressure-area isotherm. This was visualized by AFM as stripes of a condensed phase within the expanded phase, exhibiting a small height difference but a significant difference in friction. The corresponding phase transition of the palmitic acid was continuous, and no changes of the Langmuir-Blodgett films with respect to pressure were observed with AFM. Both the surface pressure-area isotherms and the direct observations of domains of irregular size and shape using the AFM showed that lignoceric and palmitic acid were immiscible. The height difference between the domains was 1.1 nm corresponding to the difference in hydrocarbon chain length of the two fatty acids.
(Less)
- author
- Ekelund, K. LU ; Sparr, E. LU ; Engblom, J. LU ; Wennerström, H. LU and Engström, S.
- organization
- publishing date
- 1999-09-28
- type
- Contribution to journal
- publication status
- published
- subject
- in
- Langmuir
- volume
- 15
- issue
- 20
- pages
- 4 pages
- publisher
- The American Chemical Society (ACS)
- external identifiers
-
- scopus:0032671925
- ISSN
- 0743-7463
- DOI
- 10.1021/la990092+
- language
- English
- LU publication?
- yes
- id
- 6ac58ec9-5c67-4cc0-9d9d-16072dafcd27
- date added to LUP
- 2023-12-07 15:00:21
- date last changed
- 2023-12-11 11:13:17
@article{6ac58ec9-5c67-4cc0-9d9d-16072dafcd27,
abstract = {{<p>Monolayers of palmitic (C16:0) and lignoceric acid (C24:0) and their equimolar mixture were transferred to a hydrophilic mica substrate at various surface pressures and investigated by means of atomic force microscopy (AFM) in contact and lateral force modes. The first-order transition of lignoceric acid gives a plateau region, representing a liquid expanded to liquid condensed phase transition in the pressure-area isotherm. This was visualized by AFM as stripes of a condensed phase within the expanded phase, exhibiting a small height difference but a significant difference in friction. The corresponding phase transition of the palmitic acid was continuous, and no changes of the Langmuir-Blodgett films with respect to pressure were observed with AFM. Both the surface pressure-area isotherms and the direct observations of domains of irregular size and shape using the AFM showed that lignoceric and palmitic acid were immiscible. The height difference between the domains was 1.1 nm corresponding to the difference in hydrocarbon chain length of the two fatty acids.</p>}},
author = {{Ekelund, K. and Sparr, E. and Engblom, J. and Wennerström, H. and Engström, S.}},
issn = {{0743-7463}},
language = {{eng}},
month = {{09}},
number = {{20}},
pages = {{6946--6949}},
publisher = {{The American Chemical Society (ACS)}},
series = {{Langmuir}},
title = {{AFM study of lipid monolayers. 1. Pressure-induced phase behavior of single and mixed fatty acids}},
url = {{http://dx.doi.org/10.1021/la990092+}},
doi = {{10.1021/la990092+}},
volume = {{15}},
year = {{1999}},
}