title: Bloch surface wave-enhanced fluorescence biosensor.
abstract: A new approach to signal amplification in fluorescence-based assays for sensitive detection of molecular analytes is reported. It relies on a sensor chip carrying a one-dimensional photonic crystal (1DPC) composed of two piled up segments which are designed to increase simultaneously the excitation rate and the collection efficiency of fluorescence light. The top segment supports Bloch surface waves (BSWs) at the excitation wavelength and the bottom segment serves as a Bragg mirror for the emission wavelength of used fluorophore labels. The enhancement of the excitation rate on the sensor surface is achieved through the resonant coupling to BSWs that is associated with strong increase of the field intensity. The increasing of collection efficiency of fluorescence light emitted from the sensor surface is pursued by using the Bragg mirror that minimizes its leakage into a substrate and provides its beaming toward a detector. In order to exploit the whole evanescent field of BSW, extended three-dimensional hydrogel-based binding matrix that is functionalized with catcher molecules is attached to 1DPC for capturing of target analyte from a sample. Simulations supported by experiments are presented to illustrate the design and determined the performance characteristics of BSW-enhanced fluorescence spectroscopy. A model immunoassay experiment demonstrates that the reported approach enables increasing signal to noise ratio, resulting in about one order of magnitude improved limit of detection (LOD) with respect to regular total internal reflection fluorescence (TIRF) configuration.
authors.affiliation: AIT-Austrian Institute of Technology GmbH, BioSensor Technologies, Muthgasse 11, 1190 Vienna, Austria.
authors.forename: Koji
authors.initials: K
authors.lastname: Toma
authors.forename: Emiliano
authors.initials: E
authors.lastname: Descrovi
authors.forename: Mana
authors.initials: M
authors.lastname: Toma
authors.forename: Mirko
authors.initials: M
authors.lastname: Ballarini
authors.forename: Pietro
authors.initials: P
authors.lastname: Mandracci
authors.forename: Fabrizio
authors.initials: F
authors.lastname: Giorgis
authors.forename: Anca
authors.initials: A
authors.lastname: Mateescu
authors.forename: Ulrich
authors.initials: U
authors.lastname: Jonas
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Knoll
authors.forename: Jakub
authors.initials: J
authors.lastname: Dostálek
mesh_terms: D015374:Biosensing Techniques / Q000295:instrumentation*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D007909:Lenses; D012031:Refractometry / Q000295:instrumentation*; D013050:Spectrometry, Fluorescence / Q000295:instrumentation*; D020349:Surface Plasmon Resonance / Q000295:instrumentation*