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Molecularly imprinted polymers (MIPs), human-made polymers capable of recognizing a particular molecule in the presence of others due to the selective cavities of the material, have been successfully applied to the development of chromatographic and solid phase extraction methods. They have also been applied to the development of electrochemical, piezoelectrical and optical sensors. In parallel with the classification of biosensors, MIP-based devices can work according to two different detection schemes: (1) affinity sensors ("plastic-bodies") and, (2) catalytic sensors ("plastic-enzymes"). In the first case the change in a characteristic optical property, most frequently fluorescence, of the analyte or of the polymer is monitored, upon their mutual interaction. Alternatively, a fluorescent analogue of the target analyte can also be used to develop sensors based on competitive assays (MIAs). Optimization of the polymer composition and, in particular, a proper choice of the nature of the functional monomers involved in the polymerization process, is critical to prepare materials able to selectively interact with the analyte in aqueous media and with the fast kinetics required for analytical applications. Moreover, a rational design of fluorescent analogues of non-naturally fluorescent templates or of fluorescent monomers able to change its property upon interaction with the analyte, is also a bottle neck for wide application of this recognition elements in optical sensing. In this paper we present several approaches to address these issues namely the optimization of MIP composition and the design and synthesis of novel fluorophores for the analysis of antibiotics and mycotoxins in real samples.

The state-of-the-art of carbon dioxide fiberoptic sensing, using both steady-state and time- resolved luminescence measurements, is briefly reviewed. Particular emphasis is given to the authors' own research on carbon dioxide optical monitoring via an excited-state proton transfer to luminescent ruthenium (II) chelate complexes. This kind of pH transduction chemistry allows for determination of the analyte in gas or liquid phase using both emission intensity- and lifetime-based optodes using the technology (sources, detectors, electronics) already developed for optical fiber oxygen sensing. Relevant factors that affect the performance of CO2 luminescent optosensors, such as the structure of the indicator dye, the immobilization procedure and support, the internal buffer of the sensitive layers and the working principle, are discussed as well. Finally, some recent applications in the authors' laboratories to fiberoptic carbon dioxide monitoring in spring water samples are presented.© (1995) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

The luminescence emission (652 nm) and lifetime (390 ns) of a novel Ru(II) tris-chelate complex tris(2-(2-pyrazinyl)thiazole)ruthenium(II) are quenched by H30 and other acids (phosphoric acetic phthalic and dihydrogenphosphate) in aqueous solution. The quenching process is shown to occur via a proton transfer to the excited (triplet state) complex since the ground state complex undergoes no protonation in the 0-12 pH interval (pKai 1. 9). Quenching rate constants in the range 1 x 108 to 5x iO M1s1 have been measured. The pH transducing system has been tested in solution using carbon dioxide and has been applied to the construction of a bifurcated fiber optic chemical sensor for this gas. Advantages of employing Ru(pzth)32 as a luminescent dye includeamong others: (1) a hydrogen carbonate buffer is not required in the reservoir chamber and (2) excitation in the visible region using inexpensive plastic optical fibers and collection of the emission through cut-off filters is feasible.