title: Characterisation and optimisation of an immunoprobe for triazines.
abstract: The characterisation and optimisation of an optical immunoassay with label free detection based on Reflectometric Interference Spectroscopy (RIfS) is presented. The immunoprobe is operated in a sequential scheme, where Fab-fragments react with analyte molecules in a first step. In a second step the optical transducer is used to quantify the amount of unoccupied Fab- fragments in the reaction mixture binding to the hapten-modified transducer surface. For optimisation of the test, the Fab-fragment concentration was varied between 2x10(-8) mol/l and 2.5x 10(-9) mol/l. Down to a concentration of 5x10(-9) mol/l a reduction in the limit of detection has been observed. At the lowest concentration investigated no further improvement has been found due to a reduced binding of the analyte and a strong decrease of antibody binding at the transducer surface. This finding could be explained by the thermodynamics of the antigen-antibody reaction and the performance of the optical transducer used. The limit of detection obtained is discussed with respect to thermodynamics, transducer characteristics and immunoprobe test format.
authors.affiliation: Institut für Physikalische und Theoretische Chemie, Universität Tübingen, Auf der Morgenstelle 8, D-72076, Tübingen, Germany.
authors.forename: G
authors.initials: G
authors.lastname: Lang
authors.forename: A
authors.initials: A
authors.lastname: Brecht
authors.forename: G
authors.initials: G
authors.lastname: Gauglitz