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Sensors 2011, 11(3), 3004-3019; doi:10.3390/s110303004
Communication

Photonic Biosensor Assays to Detect and Distinguish Subspecies of Francisella tularensis

1
, 2
, 1
, 1
 and 2,*
Received: 15 January 2011; in revised form: 15 February 2011 / Accepted: 2 March 2011 / Published: 7 March 2011
(This article belongs to the Section Biosensors)
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Abstract: The application of photonic biosensor assays to diagnose the category-A select agent Francisella tularensis was investigated. Both interferometric and long period fiber grating sensing structures were successfully demonstrated; both these sensors are capable of detecting the optical changes induced by either immunological binding or DNA hybridization. Detection was made possible by the attachment of DNA probes or immunoglobulins (IgG) directly to the fiber surface via layer-by-layer electrostatic self-assembly. An optical fiber biosensor was tested using a standard transmission mode long period fiber grating of length 15 mm and period 260 µm, and coated with the IgG fraction of antiserum to F. tularensis. The IgG was deposited onto the optical fiber surface in a nanostructured film, and the resulting refractive index change was measured using spectroscopic ellipsometry. The presence of F. tularensis was detected from the decrease of peak wavelength caused by binding of specific antigen. Detection and differentiation of F. tularensis subspecies tularensis (type A strain TI0902) and subspecies holarctica (type B strain LVS) was further accomplished using a single-mode multi-cavity fiber Fabry-Perot interferometric sensor. These sensors were prepared by depositing seven polymer bilayers onto the fiber tip followed by attaching one of two DNA probes: (a) a 101-bp probe from the yhhW gene unique to type-A strains, or (b) a 117-bp probe of the lpnA gene, common to both type-A and type-B strains. The yhhW probe was reactive with the type-A, but not the type-B strain. Probe lpnA was reactive with both type-A and type-B strains. Nanogram quantities of the target DNA could be detected, highlighting the sensitivity of this method for DNA detection without the use of PCR. The DNA probe reacted with 100% homologous target DNA, but did not react with sequences containing 2-bp mismatches, indicating the high specificity of the assay. These assays will fill an important void that exists for rapid, culture-free, and field-compatible diagnosis of F. tularensis.
Keywords: Francisella tularensis; diagnosis; long period fiber grating; fiber Fabry-Perot interferometric sensor; probe; antibody; DNA Francisella tularensis; diagnosis; long period fiber grating; fiber Fabry-Perot interferometric sensor; probe; antibody; DNA
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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MDPI and ACS Style

Cooper, K.L.; Bandara, A.B.; Wang, Y.; Wang, A.; Inzana, T.J. Photonic Biosensor Assays to Detect and Distinguish Subspecies of Francisella tularensis. Sensors 2011, 11, 3004-3019.

AMA Style

Cooper KL, Bandara AB, Wang Y, Wang A, Inzana TJ. Photonic Biosensor Assays to Detect and Distinguish Subspecies of Francisella tularensis. Sensors. 2011; 11(3):3004-3019.

Chicago/Turabian Style

Cooper, Kristie L.; Bandara, Aloka B.; Wang, Yunmiao; Wang, Anbo; Inzana, Thomas J. 2011. "Photonic Biosensor Assays to Detect and Distinguish Subspecies of Francisella tularensis." Sensors 11, no. 3: 3004-3019.



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