Surfaces designed for charge reversal.
We have created surfaces which switch from cationic at pH < 3 to anionic at pH > 5, by attaching aminodicarboxylic acid units to silica and gold substrates. Charge reversal was demonstrated by monitoring the adsorption of cationic dyes (methylene blue and a tetracationic porphyrin) and...
| Main Authors: | , , , , |
|---|---|
| Format: | Journal article |
| Language: | English |
| Published: |
2003
|
| _version_ | 1826281708051234816 |
|---|---|
| author | Matthews, JR Tuncel, D Jacobs, R Bain, C Anderson, H |
| author_facet | Matthews, JR Tuncel, D Jacobs, R Bain, C Anderson, H |
| author_sort | Matthews, JR |
| collection | OXFORD |
| description | We have created surfaces which switch from cationic at pH < 3 to anionic at pH > 5, by attaching aminodicarboxylic acid units to silica and gold substrates. Charge reversal was demonstrated by monitoring the adsorption of cationic dyes (methylene blue and a tetracationic porphyrin) and an anionic sulfonated porphyrin, at a range of pH using UV-vis absorption and reflection spectroscopy. The cationic dyes bind under neutral conditions (pH 5-7) and are released at pH 1-4, whereas the anionic dye binds under acidic conditions (pH 1-4) and is released at pH 5-7. Gold surfaces were functionalized with two different amphoteric disulfides with short (CH(2))(2) and long (CH(2))(10)CONH(CH(2))(6) linkers; the longer disulfide gave surfaces exhibiting charge reversal in a narrower pH range. Adsorption is much faster on the functionalized gold (t(1/2) = 62 s) than on functionalized silica (t(1/2) = 6900 s), but the final extents of coverage on both surface are similar, for a given dye at a given pH, with maximal coverages of around 2 molecules nm(-)(2). These charge-reversal processes are reversible and can be repeatedly cycled by changing the pH. We have also created surfaces which undergo irreversible proton-triggered charge switching, using a carbamate-linked thiol carboxylic acid which cleaves in acid. These surfaces are versatile new tools for controlling electrostatic self-assembly at surfaces. |
| first_indexed | 2024-03-07T00:32:52Z |
| format | Journal article |
| id | oxford-uuid:8069f43f-e3c2-43ef-b6eb-c089ead320c4 |
| institution | University of Oxford |
| language | English |
| last_indexed | 2024-03-07T00:32:52Z |
| publishDate | 2003 |
| record_format | dspace |
| spelling | oxford-uuid:8069f43f-e3c2-43ef-b6eb-c089ead320c42022-03-26T21:23:09ZSurfaces designed for charge reversal.Journal articlehttp://purl.org/coar/resource_type/c_dcae04bcuuid:8069f43f-e3c2-43ef-b6eb-c089ead320c4EnglishSymplectic Elements at Oxford2003Matthews, JRTuncel, DJacobs, RBain, CAnderson, HWe have created surfaces which switch from cationic at pH < 3 to anionic at pH > 5, by attaching aminodicarboxylic acid units to silica and gold substrates. Charge reversal was demonstrated by monitoring the adsorption of cationic dyes (methylene blue and a tetracationic porphyrin) and an anionic sulfonated porphyrin, at a range of pH using UV-vis absorption and reflection spectroscopy. The cationic dyes bind under neutral conditions (pH 5-7) and are released at pH 1-4, whereas the anionic dye binds under acidic conditions (pH 1-4) and is released at pH 5-7. Gold surfaces were functionalized with two different amphoteric disulfides with short (CH(2))(2) and long (CH(2))(10)CONH(CH(2))(6) linkers; the longer disulfide gave surfaces exhibiting charge reversal in a narrower pH range. Adsorption is much faster on the functionalized gold (t(1/2) = 62 s) than on functionalized silica (t(1/2) = 6900 s), but the final extents of coverage on both surface are similar, for a given dye at a given pH, with maximal coverages of around 2 molecules nm(-)(2). These charge-reversal processes are reversible and can be repeatedly cycled by changing the pH. We have also created surfaces which undergo irreversible proton-triggered charge switching, using a carbamate-linked thiol carboxylic acid which cleaves in acid. These surfaces are versatile new tools for controlling electrostatic self-assembly at surfaces. |
| spellingShingle | Matthews, JR Tuncel, D Jacobs, R Bain, C Anderson, H Surfaces designed for charge reversal. |
| title | Surfaces designed for charge reversal. |
| title_full | Surfaces designed for charge reversal. |
| title_fullStr | Surfaces designed for charge reversal. |
| title_full_unstemmed | Surfaces designed for charge reversal. |
| title_short | Surfaces designed for charge reversal. |
| title_sort | surfaces designed for charge reversal |
| work_keys_str_mv | AT matthewsjr surfacesdesignedforchargereversal AT tunceld surfacesdesignedforchargereversal AT jacobsr surfacesdesignedforchargereversal AT bainc surfacesdesignedforchargereversal AT andersonh surfacesdesignedforchargereversal |