Schizophrenie Molecules and Materials with Multiple Personalities - How Materials Science could Revolutionise How we do
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Schizophrenic Molecules and Materials with Multiple Personalities - How Materials Science could Revolutionise How we do Chemical Sensing. Robert Byrne, Silvia Scaramagnani, Alek Radu, Fernando Benito-Lopez and Dermot Diamond. CLARITY: Centre for Sensor Web Technologies, National Centre for Sensor Research, School of Chemical Sciences, Dublin City University, Dublin 9, Ireland.
Abstract Molecular photoswitches like spiropyrans derivatives offer exciting possibilities for the development of analytical platforms incorporating photo-responsive materials for functions such as light-activated guest uptake and release and optical reporting on status (passive form, free active form, guest bound to active form). In particular, these switchable materials hold tremendous promise for microflow-systems, in view of the fact that their behaviour can be controlled and interrogated remotely using light from LEDs, without the need for direct physical contact. We demonstrate the immobilisation of these materials on microbeads which can be incorporated into a microflow system to facilitate photoswitchable guest uptake and release. We also introduce novel hybrid materials based on spiropyrans derivatives grafted onto a polymer backbone which, in the presence of an ionic liquid, produces a gel-like material capable of significant photoactuation behaviour. We demonstrate how this material can be incorporated into microfluidic platforms to produce valve-like structures capable of controlling liquid movement using light.
Introduction Chemical sensors are devices that provide information about binding events happening at the interface between a sensitive film/membrane and a sample phase. The function of the sensitive film/membrane is to ensure that the binding at this interface is as selective as possible usually by means of entrapped or covalently bound receptor sites. The binding event is further coupled with a transduction mechanism of some kind; such as a change in the colour or fluorescence of the film or a change in electrochemical potential. Clearly, these materials are ‘active’ as binding events must occur for them to be of any analytical use. However, it is self-evident that these sensitive interfaces will change over time, for example due non-specific binding and biofouling in real samples that can lead to surface poisoning or occlusion, or leaching of active components into the sample phase. Consequently, the response characteristics of chemical sensors and biosensors will change with time, leading to gradual decrease in sensitivity, loss of selectivity and baseline drift. In practice, these effects are compensated for by regular calibration, until the device deterioration reaches some limiting level. In recent years, physical transducers have been increasingly deployed in sensor networks. However, for equivalent widely distributed chemical sensing to happen, there must be a revolution in the way chemical sensors/biosensors are employed, as conventional calibration is inappropriate for large-scale deployments due t
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