title: Label-free bacteria detection using evanescent mode of a suspended core terahertz fiber.
abstract: We propose for the first time an E. coli bacteria sensor based on the evanescent field of the fundamental mode of a suspended-core terahertz fiber. The sensor is capable of E. coli detection at concentrations in the range of 10(4)-10(9) cfu/ml. The polyethylene fiber features a 150 µm core suspended by three deeply sub-wavelength bridges in the center of a 5.1 mm-diameter cladding tube. The fiber core is biofunctionalized with T4 bacteriophages which bind and eventually destroy (lyse) their bacterial target. Using environmental SEM we demonstrate that E. coli is first captured by the phages on the fiber surface. After 25 minutes, most of the bacteria is infected by phages and then destroyed with ~1 μm-size fragments remaining bound to the fiber surface. The bacteria-binding and subsequent lysis unambiguously correlate with a strong increase of the fiber absorption. This signal allows the detection and quantification of bacteria concentration. Presented bacteria detection method is label-free and it does not rely on the presence of any bacterial "fingerprint" features in the THz spectrum.
authors.affiliation: École Polytechnique de Montréal, Génie Physique, Québec, Canada.
authors.forename: Anna
authors.initials: A
authors.lastname: Mazhorova
authors.forename: Andrey
authors.initials: A
authors.lastname: Markov
authors.forename: Andy
authors.initials: A
authors.lastname: Ng
authors.forename: Raja
authors.initials: R
authors.lastname: Chinnappan
authors.forename: Olga
authors.initials: O
authors.lastname: Skorobogata
authors.forename: Mohammed
authors.initials: M
authors.lastname: Zourob
authors.forename: Maksim
authors.initials: M
authors.lastname: Skorobogatiy
mesh_terms: D017122:Bacteriophage T4 / Q000502:physiology*; D001681:Biological Assay / Q000295:instrumentation*; D015374:Biosensing Techniques / Q000295:instrumentation*; D015169:Colony Count, Microbial / Q000295:instrumentation; D004867:Equipment Design; D019544:Equipment Failure Analysis; D004926:Escherichia coli / Q000302:isolation & purification* / Q000821:virology*; D005336:Fiber Optic Technology / Q000295:instrumentation*; D020349:Surface Plasmon Resonance / Q000295:instrumentation*; D055053:Terahertz Radiation