Versatile biosensor surface based on peptide nucleic acid with label free and total internal reflection fluorescence detection for quantification of endocrine disruptors

In recent years, the simultaneous detection of hundreds of substances has become increasingly important in medical diagnostics and environmental monitoring. This calls for methods that allow fast and simultaneous measurement of many analytes and require only a minimum of attendance. Biosensor-applications including easy implementation and long-term stability of the sensor element are more and more designed to meet these demands.In this paper, a surface based on covalently immobilised peptide nucleic acid (PNA) for the detection of different endocrine disruptors is used. The surface was characterised with a label free detection system, the reflectometric interference spectroscopy (RIfS). A hybridisation capacity with DNA oligonucleotides of 1.3 ng/mm² (180 fmol/mm²) on PNA-surfaces was achieved. The PNA transducer is stable for half a year and for more than 300 regeneration steps.With this modified surface various environmentally relevant endocrine disruptors could be detected by an immunoassay. The detection is done on an optical waveguide system, based on total internal reflection fluorescence (TIRF) by using an auxiliary-system consisting of a conjugate which is formed of DNA-oligomers and analyte-derivatives. The successive detection of different analytes on the same spot by using this auxiliary-system is demonstrated as one application of multianalyte detection. Quantification of different endocrine disruptors on the same PNA-surface is demonstrated by three calibration curves.