Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
10528779 | Analytica Chimica Acta | 2005 | 10 Pages |
Abstract
A holographic sensor for real-time detection of divalent metal ions (Ca2+, Mg2+, Ni2+, Co2+ and Zn2+) has been fabricated by incorporating a chelating monomer into a hydrogel matrix. A methacrylated analogue of iminodiacetic acid (IDA) was prepared and co-polymerised with hydroxyethyl methacrylate (HEMA) and ethylene glycol dimethacrylate (EDMA) as a cross-linker to form polymer films. A silver-based reflection hologram was incorporated into the hydrogel by diffusion followed by holographic recording using a frequency-doubled Nd/YAG laser. Changes in the replay wavelength of the hologram were used to characterise the swelling behaviour of the matrix as a function of its chemical composition and concentration of analyte in the media. The effects of active monomer, cross-linker, pH and ionic strength on the swelling of the matrix and on metal detection sensitivity have been studied. Polymers containing >10Â mol% of chelating monomer and 6Â mol% of cross-linker showed significant responses (46.3Â nm) within 30Â s at an ion concentration of 0-40Â nm. The selectivity of the holograms towards the different ions tested was Ni2+>Zn2+>Co2+>Ca2+>Mg2+. The sensor showed fully reversible responses, permitting real-time monitoring of calcium ion efflux during the germination of Bacillus megaterium spores.
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Authors
Blanca Madrigal González, Graham Christie, Colin A.B. Davidson, Jeff Blyth, Christopher R. Lowe,