Real-time analysis using molecular-imprinted polymers.

An objective of European research is to develop molecular-imprinted polymers (MIPs) that can be used with other detection techniques- immunoassays and sensors-to measure levels, in real time, of microorganisms, chemical contaminants and biopolymers in foods. Molecular imprinting involves the synthesis of polymers in the presence of an imprint or template compound (the substance to be analyzed or analyte) to produce cavities on the polymer that are selective for that analyte. Foods can be tested for the analyte by extracting it into solution and then selectively binding it using the MIP. Then quantification is performed using immunoassay or sensor technology. Advantages of MIPs include simple preparation, high stability, high binding affinity and capacity, and low cost.

Researchers have developed MIPs for small molecules, and imprints have been successfully developed for penicillin V, penicillin G and oxacillin. Chromatographic analysis of the MIPs in organic solvents showed a clear imprinting effect for all the polymer systems tested, together with specificity for the lactam antibiotics.

The MIPs for clenbuterol were highly porous, indicating a high surface area and rapid diffusion of clenbuterol to the imprinted cavities. Relatively poor imprinting was observed for tetracyclines.

Research is continuing on the development of MIPs for large molecules, carrageenan oligosaccharides and Salmonella. Scientists also are developing integrated MIP-based sensors. The MIP-based technology is expected to be of use in monitoring a wide range of foods, including milk, fermented milk products, meats, cooked dishes and baby foods.

Further information. P. Patel, Rapid Methods Section, Leatherhead Food Research Association, Randalls Road, Leatherhead, Surrey, KT22 7RY, England, U.K.; phone: [phone]; fax: [phone]; email: [e-mail].