Photonically controlled self-indicationg micro-capillary systems for metal ion accumulation and release
Florea, Larisa and Diamond, Dermot and Benito-Lopez, Fernando (2011) Photonically controlled self-indicationg micro-capillary systems for metal ion accumulation and release. In: 11th Asia Pacific International Symposium on Microscale Separations and Analysis, 27–30 Nov 2011, Hobart, Australia.
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Photocromic polymer brushes were synthesised on the interior of fused silica micro-capillaries using the “grafting from” approach . This technique enables high surface loadings of the stimuli-responsive polymer in a limited area and enhances the switching effect compared to conventional films.
Upon irradiation with UV light the passive spiropyran (SP) unit undergoes a heterocyclic ring cleavage that results in the merocyanine (MC) formation . In contrast to the uncharged and colourless spiropyran form, the merocyanine is highly charged and can be utilised as ligand for other charged species. Based on the coordination-induced photochromism characteristic of the MC form, we focus our studies in the photo-controlled detection of target metal ions when flowing through the modified micro-capillaries. Using this approach we have created a photonically controlled self-indicating system for metal ion detection that will ensure real-time measurements and fast analysis protocols in systems and micro-systems that operate in continuous flow (e.g. analytical devices like HPLC, CE or micro-chips).
Investigations into the metal-ion binding behaviour of the spiropyran-polymer brushes have shown that they are capable of binding different metals ions (Cu2+, Ni2+, Co2+) causing an appreciable colour and spectral change when exposed to UV light while a solution of these metals ions is passed through the capillary. Moreover, these ions can be released by photonic-conversion of the MC moiety into the inactive SP form using white light. This sequence can be successfully repeated, suggesting that this sensing behaviour can be switched on/off remotely using light, either along the entire length of the capillary, or at patterned locations using the appropriate mask.
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