Reversible surface thiol immobilization of carboxyl group containing haptens to a BIAcore biosensor chip enabling...

We describe a reversible immobilization method for carboxyl group containing haptens that makes the repeated usage of a BIAcore biosensor chip possible. Haptens which are immobilized according to the surface thiol method can be removed completely from the sensor surface again by a reducing step. In the first part of our study, analogues of the herbicides 2,4-dichlorophenoxyacetic acid and 2,4,5-trichlorophenoxyacetic acid were immobilized in succession to a biosensor surface of a BIAcore surface plasmon resonance instrument according to the thiol coupling method. Direct kinetic analysis of these ligands to a polyclonal anti-2,4-dichlorophenoxyacetic acid antibody were performed using these biosensor surfaces. In the second part of the study, different amounts of 2,4-dichlorophenoxyacetic acid were sequentially immobilized onto the same biosensor surface in order to generate a calibration plot for 2,4-dichlorophenoxyacetic acid. Using this plot, the quantitative detection of the herbicide down to a concentration of 0.1 microg/mL, the maximum admissible concentration of pesticides in drinking water, is possible.