Optimization of immunochemistry for sensing techniques to detect pesticide residues in water

We are working on the development of a real-time electrochemical sensor based on an immunoassay detection system to detect and quantify the presence of pesticide residues in ground water. Highly selective and sensitive immuno-reactions are being investigated to be optimized in order to bring them into the level of real-time in-line sensors. In this project a competitive immunoassay between surface immobilized 2,6-dichlorobenzamide (BAM) haptens and BAM present in the water sample using an anti-BAM monoclonal antibody is being described. 2,6-Dichlorobenzamide (BAM) is a degradation product of the herbicide, dichlobenil which has been used extensively in the past and it is among the most frequently found pesticide residues in European ground water. BAM is highly resistant to further degradation and is fairly soluble in water. We have synthesized and immobilized a small library of BAM haptens and compared the affinity constants of the antibody towards this library. Furthermore, since regeneration of the BAM-hapten surface is a prerequisite for the development of a real-time electrochemical sensor with immunoassay-based detection, studies on regeneration of surfaces, modified with the newly synthesized BAM-haptens has been preformed and compared and correlated to the measured affinity constants. By using conventional ELISA we were able to indicate that one of the immobilized BAM haptens with an intermediate affinity towards the anti-BAM antibody was better in terms of regeneration. Design and fabrication of a fully automated microfluidic based on this immunoassay and electrochemical detection are in progress.