title: A double-taper optical fiber-based radiation wave other than evanescent wave in all-fiber immunofluorescence biosensor for quantitative detection of Escherichia coli O157:H7.
abstract: Cylindrical or taper-and-cylinder combination optical fiber probe based on evanescent wave has been widely used for immunofluorescence biosensor to detect various analytes. In this study, in contrast to the contradiction between penetration depth and analyte diameter of optical fiber probe-based evanescent wave, we demonstrate that double-taper optical fiber used in a radiation wave-based all-fiber immunofluorescence biosensor (RWAIB) can detect micron-scale analytes using Escherichia coli O157:H7 as representative target. Finite-difference time-domain method was used to compare the properties of evanescent wave and radiation wave (RW). Ray-tracing model was formulated to optimize the taper geometry of the probe. Based on a commercial multi-mode fiber, a double-taper probe was fabricated and connected with biosensor through a "ferrule connector" optical fiber connector. The RWAIB configuration was accomplished using commercial multi-mode fibers and fiber-based devices according to the "all-fiber" method. The standard sample tests revealed that the sensitivity of the proposed technique for E. coli O157:H7 detection was 10(3) cfu · mL(-1). Quantitation could be achieved within the concentration range of 10(3) cfu · mL(-1) to 107 cfu · mL(-1). No non-specific recognition to ten kinds of food-borne pathogens was observed. The results demonstrated that based on the double-taper optical fiber RWAIB can be used for the quantitative detection of micron-scale targets, and RW sensing is an alternative for traditional evanescent wave sensing during the fabrication of fiber-optic biosensors.
authors.affiliation: State Key Laboratory of Precision Measurement Technology and Instrument, Department of Precision Instruments, Tsinghua University, Beijing, P.R. of China.
authors.forename: Zhonghuan
authors.initials: Z
authors.lastname: Zhang
authors.affiliation: Laboratory of Analytical Microbiology, State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, P.R. of China; Department of Aetiology, Taishan Medical University, Taian, P.R. of China.
authors.forename: Fei
authors.initials: F
authors.lastname: Hua
authors.affiliation: State Key Laboratory of Precision Measurement Technology and Instrument, Department of Precision Instruments, Tsinghua University, Beijing, P.R. of China.
authors.forename: Ting
authors.initials: T
authors.lastname: Liu
authors.affiliation: Laboratory of Analytical Microbiology, State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, P.R. of China.
authors.forename: Yong
authors.initials: Y
authors.lastname: Zhao
authors.affiliation: State Key Laboratory of Precision Measurement Technology and Instrument, Department of Precision Instruments, Tsinghua University, Beijing, P.R. of China.
authors.forename: Jun
authors.initials: J
authors.lastname: Li
authors.affiliation: Laboratory of Analytical Microbiology, State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, P.R. of China.
authors.forename: Ruifu
authors.initials: R
authors.lastname: Yang
authors.affiliation: State Key Laboratory of Precision Measurement Technology and Instrument, Department of Precision Instruments, Tsinghua University, Beijing, P.R. of China.
authors.forename: Changxi
authors.initials: C
authors.lastname: Yang
authors.affiliation: Laboratory of Analytical Microbiology, State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, P.R. of China.
authors.forename: Lei
authors.initials: L
authors.lastname: Zhou
mesh_terms: D015374:Biosensing Techniques / Q000379:methods*; D019453:Escherichia coli O157 / Q000302:isolation & purification*; D005336:Fiber Optic Technology / Q000379:methods*