| Summary: | Molecular imprinting is a technique used for the construction of synthetic polymers containing binding sites which have a high and selective affinity for a target molecule. Molecularly imprinted polymers (MIPs) can be used in sensors, to bind an analyte and then generate a signal, or in competitive binding assays, where an analyte and a probe molecule compete for .binding to a limited number of binding sites. (MIPs) are often termed 'antibody mimics', although clear advantages of MIPs are apparent when they are used in place of antibodies. MIPs are more stable and robust, inexpensive to produce and can be stored dry at room temperature for substantial periods of time. The development of MIP technologies is also desirable because their production does not require the sacrifice of animals, which is necessary for the generation of antibodies. Methods which could be employed to assess the binding of an analyte to a MIP directly in solution without needing to separate the polymer from solution have been developed, detecting the binding of the drug (S)-propranolol to MIPs, by an increase in fluorescence anisotropy in toluene, or by a shift in the peak fluorescence emission wavelength of (S)-propranolol in aqueous buffer. These methods were used to show that a (S)-propranolol imprinted polymer bound (S)-propranolol more strongly than it did (R)-propranolol, and more strongly than a non-imprinted polymer did. These methods would be particularly useful for rapidly comparing the binding properties of a number of polymers, e.g. where libraries of polymers are being screened to find the one that binds (S)-propranolol most strongly or Joost selectively. The development of competitive binding assays which do not require a time consuming separation step and which do not involve undesirable radiolabels has also been attempted. A fluorescence polarisation immunoassay and a fluorescence intensity based immunoassay for the pesticide 2,4-D were developed. These assays represent a significant advance over previously reporte,d MIP-immunoassays because they use a non-radiolabelled probe and do not .. . . require separation of the polymer from solution. The assay in buffer could be used in the field as a quick screen for 2,4-D related pesticides in contaminated water supplies. It was also attempted to develop MIPs containing a fluorescent acrylarnidofluorescein reporter group as sensors f~r (-)-ephedrine or (S)-propranolol. The binding of analyte to the polymers resulted in an increase in fluorescence, due to deprotonation of the fluorescein moiety. Fluorescence detection methods have shown potential for MIP screening libraries, and MIPs . have been shown to be viable replacements for antibodies in sensor and immunoassay applications.
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