Food safety and quality are fundamental obligations towards the European consumer as clearly identified in the proposal "Agenda 2000" towards of the Common Agricultural Policy. The consumer and authorities are concerned about the problem of food safety (e.g. microbiological and chemical contamination), and environmental issues (e.g. animal welfare). The European Commission has proposed to adopt harmonised rules at Community level for matters relating to public health, the protection of the consumers, fairness to trade and environmental protection. There are several relevant directives which include microbiological criteria (e.g. Council Directives 92/46/EEC, 94/65/EC, 89/437/EEC, 91/493/EEC and 80/777/EEC) for food safety control taking also into account that food-borne illnesses leading to consumer's health damage need to be avoided such as these ones reported in 1990, where an average of 120 cases of food-borne illness per 100,000 population from 11 European Countries occurred. Many of the modern techniques (e.g. ELISA, PCR and HPLC) for the analysis of food contaminants are not wholly reliable, robust, real-time or suited to line sample measurement. This is largely due to two significant problems, i.e. the interference of components from bulk food matrix and potential cross-reactions with closely related species. To address these problems, generic techniques are required that reproducibly separate analytes from potential interference in real-time prior to detection and estimation.
The major objective of MICROSENSOR project is to develop and demonstrate the practical feasibility of miniaturised free flow electrophoresis (mFFE) -based optical biosensor techniques for real-time measurement of analytes (e.g. markers of rBST hormone and Listeria), as a generic tool to address the problem of food safety. If successful, the new analytical technology will enhance: (i) food safety by providing efficient tools to cope with modern food production, and (ii) efficiency of European Food Control laboratories. Consequently, it is the strategic objective of this project to test the practical feasibility of mFFE systems with downstream dedicated sensors for the realtime measurement of three selected analytes (e.g. mycotoxin, markers for recombinant bovine somatotrophin, rBST, and Listeria) as a tool to address selected problems of food safety. The proposed research aims to deliver such techniques by using a multidisciplinary approach integrating the novel generic mFFE separation techniques, a solid state optical biosensor system and associated software for the measurement of the selected food contaminants in comparison with the conventional techniques.
The literature reviews on the applications of FFE and biosensors in the agrifood industry have been published as LFRA reports. Further external publication of the biosensor paper has been secured in the Trends in Analytical Chemistry (TRAC) Journal.
Work has continued on the development of miniaturised FFE systems. Standard procedures for microfabrication of polydimethylsiloxane (PDMS) chip devices have been established, permitting the rapid and cost-effective production of multiple copies. The - 231 - first-design prototype of a microchip, with media flow regulated by a vacuum pump, has been fabricated for use with a linear array UV detector. The integrity and functionality of the structure has been successfully demonstrated by resolving the fluorescent compounds, fluorescein and rhodamine. The microchip magnet design concept has been patented.
Work has also continued on the development of prototype mini-FFE chambers for the separation of Listeria and IGF-1. Continuous isotachophoresis was used to resolve Listeria and Micrococcus from a mixed suspension. Sample capacity was increased using simultaneous manifold separations. The robustness of the mini-chambers was improved by developing a new supporting frame to equalise the pressure across the chambers. Following successful reliability trials, the mini-FFE instrument was technology transferred to the food laboratory for the development of practical protocols. Free flow zone electrophoresis and isotachophoresis have since been used to determine the characteristic profiles of Listeria, Micrococcus and E.coli using the mini-FFE instrument.
Work has continued on the development of suitable detection systems for use with the mFFE. Work was instigated on development of SPR sensor based assay procedures for Listeria. Selective binding profiles of antibody and bacterial cells have been demonstrated using gold-coated glass slides of a commercial optical biosensor. The ASI biosensor has been tested for stability, and recently transferred to the food laboratory for protocol development.