Title: Photoreversible ion-binding using spiropyran modified silica microbeads

Authors: Silvia Scarmagnani, Conor Slater, Fernando Benito-Lopez, Dermot Diamond, Zarah Walsh, Brett Paull, Mirek Macka

Addresses: Adaptive Sensors Group, National Centre for Sensor Research, Dublin City University, Dublin 9, Ireland. ' Adaptive Sensors Group, National Centre for Sensor Research, Dublin City University, Dublin 9, Ireland. ' Adaptive Sensors Group, National Centre for Sensor Research, Dublin City University, Dublin 9, Ireland. ' Adaptive Sensors Group, National Centre for Sensor Research, Dublin City University, Dublin 9, Ireland. ' School of Chemical Sciences and National Centre for Sensor Research, Dublin City University, Dublin 9, Ireland.' School of Chemical Sciences and National Centre for Sensor Research, Dublin City University, Dublin 9, Ireland.' School of Chemical Sciences and National Centre for Sensor Research, Dublin City University, Dublin 9, Ireland

Abstract: In this paper, we report the covalent immobilisation of spiropyran on silica microbeads of 5 μm diameter and subsequent evaluation of the photoswitchable behaviour and light-modulated ion-binding properties of the spiropyran modified silica microbeads towards a range of different metal ions. The beads can be effectively switched using light emitting diodes between a white spiropyran form (by irradiation with a white 430-760 nm light emitting diode) and a pink merocyanine form (upon irradiation with a UV light 375 nm emitting diodes) that undergoes, under exposure to certain metal ions (such as Cu²⁺ and Zn²⁺, final concentration of 7.7 × 10⁻⁴ M in ethanol solution), a further reversible spectral and colour change due to the formation of merocyanine-metal ion complexes. Furthermore, the accumulated ions can subsequently released from the beads on demand using light emitting diodes to reform the inactive spiro form.

Keywords: photoreversible ion binding; spiropyran; functionalised silica microbeads; adaptive material; covalent immobilisation; molecular photoswitches; light emitting diodes; LED; nanomaterials; nanotechnology.

DOI: 10.1504/IJNM.2010.029921

International Journal of Nanomanufacturing, 2010 Vol.5 No.1/2, pp.38 - 52

Published online: 03 Dec 2009 *

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