Resolving the structure of a model hydrophobic surface: DODAB monolayers on mica
The properties and interactions of hydrophobic surfaces in water are determining factors in a wide range of industrial applications, and represent a fundamental scientific problem that is far from solved. Langmuir-Blodgett (LB) lipid monolayers have often been used as model hydrophobic surfaces, but...
| Main Authors: | , , , , , |
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| Format: | Journal article |
| Language: | English |
| Published: |
2012
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| _version_ | 1826277963320000512 |
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| author | Gosvami, N Parsons, E Marcovich, C Berkowitz, M Hoogenboom, B Perkin, S |
| author_facet | Gosvami, N Parsons, E Marcovich, C Berkowitz, M Hoogenboom, B Perkin, S |
| author_sort | Gosvami, N |
| collection | OXFORD |
| description | The properties and interactions of hydrophobic surfaces in water are determining factors in a wide range of industrial applications, and represent a fundamental scientific problem that is far from solved. Langmuir-Blodgett (LB) lipid monolayers have often been used as model hydrophobic surfaces, but are only metastable, which compromises the interpretation of experiments. Using frequency-modulation atomic force microscopy (FM-AFM), we find that LB-deposited monolayers of dioctadecyldimethylammonium bromide (DODAB) on mica undergo two transitions upon immersion in water: (i) a rapid molecular rearrangement from a complete monolayer coverage to a more densely packed monolayer with holes exposing the mica substrate, followed by; (ii) a gradual flipping of lipids in the monolayer to form bilayers, at a timescale of many days, orders of magnitudes slower than previously reported. The (meta)stability of the monolayer shows little dependence on the deposition pressure (5-25 mN m -1), but strongly depends on the cleanliness of the preparation and, in AFM experiments, is reduced from days to minutes when the force applied by the AFM tip is not kept to well below 1 nN. When properly prepared and analysed, the DODAB/mica surface thus yields a well-defined structure of sufficient stability to study intersurface forces, albeit with a heterogeneity that gives rise to very distinct forces above the bare mica on one hand, and on the monolayer and bilayer areas on the other. © The Royal Society of Chemistry 2012. |
| first_indexed | 2024-03-06T23:36:49Z |
| format | Journal article |
| id | oxford-uuid:6df1bccc-a1e8-455b-aab6-e33bdfa99f27 |
| institution | University of Oxford |
| language | English |
| last_indexed | 2024-03-06T23:36:49Z |
| publishDate | 2012 |
| record_format | dspace |
| spelling | oxford-uuid:6df1bccc-a1e8-455b-aab6-e33bdfa99f272022-03-26T19:21:05ZResolving the structure of a model hydrophobic surface: DODAB monolayers on micaJournal articlehttp://purl.org/coar/resource_type/c_dcae04bcuuid:6df1bccc-a1e8-455b-aab6-e33bdfa99f27EnglishSymplectic Elements at Oxford2012Gosvami, NParsons, EMarcovich, CBerkowitz, MHoogenboom, BPerkin, SThe properties and interactions of hydrophobic surfaces in water are determining factors in a wide range of industrial applications, and represent a fundamental scientific problem that is far from solved. Langmuir-Blodgett (LB) lipid monolayers have often been used as model hydrophobic surfaces, but are only metastable, which compromises the interpretation of experiments. Using frequency-modulation atomic force microscopy (FM-AFM), we find that LB-deposited monolayers of dioctadecyldimethylammonium bromide (DODAB) on mica undergo two transitions upon immersion in water: (i) a rapid molecular rearrangement from a complete monolayer coverage to a more densely packed monolayer with holes exposing the mica substrate, followed by; (ii) a gradual flipping of lipids in the monolayer to form bilayers, at a timescale of many days, orders of magnitudes slower than previously reported. The (meta)stability of the monolayer shows little dependence on the deposition pressure (5-25 mN m -1), but strongly depends on the cleanliness of the preparation and, in AFM experiments, is reduced from days to minutes when the force applied by the AFM tip is not kept to well below 1 nN. When properly prepared and analysed, the DODAB/mica surface thus yields a well-defined structure of sufficient stability to study intersurface forces, albeit with a heterogeneity that gives rise to very distinct forces above the bare mica on one hand, and on the monolayer and bilayer areas on the other. © The Royal Society of Chemistry 2012. |
| spellingShingle | Gosvami, N Parsons, E Marcovich, C Berkowitz, M Hoogenboom, B Perkin, S Resolving the structure of a model hydrophobic surface: DODAB monolayers on mica |
| title | Resolving the structure of a model hydrophobic surface: DODAB monolayers on mica |
| title_full | Resolving the structure of a model hydrophobic surface: DODAB monolayers on mica |
| title_fullStr | Resolving the structure of a model hydrophobic surface: DODAB monolayers on mica |
| title_full_unstemmed | Resolving the structure of a model hydrophobic surface: DODAB monolayers on mica |
| title_short | Resolving the structure of a model hydrophobic surface: DODAB monolayers on mica |
| title_sort | resolving the structure of a model hydrophobic surface dodab monolayers on mica |
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