Development of evanescent wave all-fiber immunosensor for environmental water analysis

A compact and portable evanescent wave all-fiber immunosensor is developed, which employs a novel single–multi-mode fiber optic coupler for exciting and collecting fluorescence emission from the fiber optic probe. Combination tapered fiber probes are produced by tube-etching method and the best tapered ratio of the probe determined is approximately 0.37. Calibration curves obtained for 2,4-dichlorophenoxyacetic acid (2,4-D) and Microcystin-LR (MC-LR) have detection limits of 0.09 μg L−1and 0.03 μg L−1, respectively. The 50% inhibition concentration (IC50) for MC-LR and 2,4-D were 1.12 ± 0.01 μg L−1and 3.81 ± 0.03 μg L−1, respectively. A reusable immunosurface is provided via the covalent attachment of the analyte derivative to a self-assembled monolayer formed onto the fiber optic probe. The regeneration of the sensor surface allows the performance of more than 100 assay cycles within an analysis time of about 20 min for each assay cycle.