Ionophore-based ion-selective potentiometric and optical sensors

This paper describes ion-selective electrodes (ISEs) and optodes with a focus on the fundamental mechanisms, response characteristics, and recognition elements (ionophores) described to date for these sensors. The topics covered review the most frequently encountered ideas about ionophore-based sensors, including the theoretical and experimental parameters that influence response, typical ionophore structures, useful membrane compositions, and applications. Since these sensors are applicable in a number of fields, such as clinical, environmental, and process monitoring, as well as more novel approaches such as microfluidic-based systems and micro/nanoprobes, this article provides descriptions that are oriented toward a more general audience. Furthermore, a large portion of this review describes the ionophore component itself in hopes of inspiring ideas in readers of how novel molecular architectures with new ionic targets or improved selectivity can be developed.