Issue 6, 2014

Oxidized polyethylene films for orienting polar molecules for linear dichroism spectroscopy

Abstract

Stretched polyethylene (PE) films have been used to orient small molecules for decades by depositing solutions on their surface and allowing the solvent to evaporate leaving the analyte absorbed on the polymer film. However, the non-polar hydrophobic nature of PE is an obstacle to aligning polar molecules and biological samples. In this work PE film was treated with oxygen plasma in order to increase surface hydrophilicity. Different treatment conditions were evaluated using contact angle measurement and X-ray photoelectron spectroscopy. Treated PE (PEOX) films are shown to be able to align molecules of different polarities including progesterone, 1-pyrenecarboxaldehyde, 4′,6-diamidino-2-phenylindole (DAPI) and anthracene. The degree of alignment of each molecule was studied by running series of linear dichroism (LD) experiments and the polarizations of electronic transition moments were determined. For the first time optimal conditions (such as stretching factor and concentration of the sample) for stretched film LD were determined. PEOX aligning ability was compared to that of normal PE films. Progesterone showed a slightly better alignment on PEOX than PE. 1-Pyrenecarboxaldehyde oriented differently on the two different films which enabled transition moment assignment for this low symmetry molecule. DAPI (which does not align on PE) aligned well on PEOX and enabled us to obtain better LD data than had previously been collected with polyvinyl alcohol. Anthracene alignment and formation of dimers and higher order structures were studied in much more detail than previously possible, showing a variety of assemblies on PE and PEOX films.

Graphical abstract: Oxidized polyethylene films for orienting polar molecules for linear dichroism spectroscopy

Supplementary files

Article information

Article type
Paper
Submitted
16 Dec 2013
Accepted
20 Jan 2014
First published
21 Jan 2014
This article is Open Access
Creative Commons BY license

Analyst, 2014,139, 1372-1382

Author version available

Oxidized polyethylene films for orienting polar molecules for linear dichroism spectroscopy

K. Razmkhah, N. P. Chmel, M. I. Gibson and A. Rodger, Analyst, 2014, 139, 1372 DOI: 10.1039/C3AN02322B

This article is licensed under a Creative Commons Attribution 3.0 Unported Licence. You can use material from this article in other publications without requesting further permissions from the RSC, provided that the correct acknowledgement is given.

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