Molecularly imprinted polymers as recognition elements in optical sensors

Custom-made fluorescent and other optical sensors for organic molecules have a wide range of potential applications [1-4]. Traditionally, such sensors have been prepared through de novo design and synthesis. For example, many very sensitive fluorescent sensors have been designed for peptides [5], metal ions [6-10], saccharides [11-13], and others [12,14-18]. However, the de novo design approach requires a thorough knowledge of the structural features of the analyte including conformational features and functional group orientations.Molecular imprinting or template-directed polymerization, on the other hand, offers an opportunity for the construction of well-defined binding cavities for a particular analyte without the prior knowledge of the three-dimensional structure of the analyte and the de novo construction of the complementary binding sites. Several other chapters in the book deal with ways to construct binding sites with high selectivity and affinity (see Part IIof thebook for detail).Therefore, thiswill not be repeated here.However, from the construction of a binding site to the development of an optical sensor, there is a huge gap.This is because a sensing device requires the output of a detectable signal. One of the major obstacles to overcome in using molecular imprinting to construct optical sensors, in addition to the problem of constructing high affinity and high selectivity binding sites, is to find a highly sensitive way to signal the binding event.