Web Release Date: January 31,
Thin-Film Modified Electrodes with Reconstituted Cellulose-PDDAC Films for the Accumulation and Detection of Triclosan
and
Department of Chemistry, University of Bath, Claverton Down, Bath BA2 7AY, UK, Department of Physics, University of Bath, Claverton Down, Bath BA2 7AY, UK, Laboratory of Aquatic Chemistry, Department of Environmental Engineering, Technical University of Crete, Polytechnioupolis, 73100 Chania-Crete, Greece, Unilever Research & Development Port Sunlight, Quarry Road, East Bebington, Wirral, CH63 3JW, UK, and Driving Innovation in Chemistry and Chemical Engineering (DICE), School of Chemistry and School of Chemical and Environmental Engineering, University of Nottingham, University Park, Nottingham NG7 2RD, UK
Received: October 6, 2007
In Final Form: November 10, 2007
Abstract:
A strategy for the formation of thin reconstituted cellulose films (pure or modified)) with embedded receptors
or embedded ion-selective components is reported. Cellulose nanofibril ribbons from sisal of typically 3-5
nm diameter and 250 nm length are reconstituted into thin films of typically 1.5-2.0 
m thickness (or into
thicker free-standing films). Cellulose and cellulose nanocomposite films are obtained in a simple solvent
evaporation process. Poly-(diallyldimethylammonium chloride) or PDDAC is readily embedded into the
cellulose film and imparts anion permselectivity to allow binding and transport of hydrophobic anions. The
number of binding sites is controlled by the amount of PDDAC present in the film. The electrochemical
properties of the cellulose films are investigated first for the Fe(CN)63-/4- model redox system and then for
the accumulation and detection of triclosan (2,4,4'-trichloro-2'-hydroxydiphenyl ether, a hydrophobic
polychlorinated phenol). Pure nanocellulose thin films essentially block the access to the electrode surface
for anions such as Fe(CN)63- and Fe(CN)64-. In contrast, in the presence of cellulose-PDDAC films,
accumulation and transport of both Fe(CN)63- and Fe(CN)64- in electrostatic binding sites occurs (Langmuirian
binding constants for both are about 1.2 × 104 mol-1 dm3 in aqueous 0.1 M KCl). Facile reduction/oxidation
at the electrode surface is observed. Triclosan, a widely used antifungal and antibacterial polychlorinated
phenol is similarly accumulated into cationic binding sites (Langmuirian binding constant about 2.1 × 104
mol-1 dm3 in aqueous 0.1 M phosphate buffer pH 9.5) and is shown to give well-defined oxidation responses
at glassy carbon electrodes. With a cellulose-PDDAC film electrode (80 wt % cellulose and 20 wt % PDDAC),
the analytical range for triclosan in aqueous phosphate buffer at pH 9.5 is about 10-6-10-3 mol dm-3.
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