Construction and Characterization of Porous SiO2/Hydrogel Hybrids as Optical Biosensors for Rapid Detection of Bacteria

Authors

  • Naama Massad-Ivanir,

    1. Department of Biotechnology and Food Engineering Technion – Israel Institute of Technology Haifa 32000 (Israel)
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  • Giorgi Shtenberg,

    1. Department of Biotechnology and Food Engineering Technion – Israel Institute of Technology Haifa 32000 (Israel)
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  • Tal Zeidman,

    1. Department of Biotechnology and Food Engineering Technion – Israel Institute of Technology Haifa 32000 (Israel)
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  • Ester Segal

    Corresponding author
    1. Department of Biotechnology and Food Engineering Technion – Israel Institute of Technology Haifa 32000 (Israel)
    2. The Russell Berrie Nanotechnology Institute Technion – Israel Institute of Technology Haifa 32000 (Israel)
    • Department of Biotechnology and Food Engineering Technion – Israel Institute of Technology Haifa 32000 (Israel)
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Abstract

The use of a new class of hybrid nanomaterials as label-free optical biosensors for bacteria detection (E. coli K12 as a model system) is demonstrated. The hybrids combine a porous SiO2 (PSiO2) optical nanostructure (a Fabry–Pérot thin film) used as the optical transducer element and a hydrogel. The hydrogel, polyacrylamide, is synthesized in situ within the nanostructure inorganic host and conjugated with specific monoclonal antibodies (IgGs) to provide the active component of the biosensor. The immobilization of the IgGs onto the hydrogel via a biotin-streptavidin system is confirmed by fluorescent labeling experiments and reflective interferometric Fourier transform spectroscopy (RIFTS). Additionally, the immobilized IgGs maintain their immunoactivity and specificity when attached to the sensor surface. Exposure of these modified-hybrids to the target bacteria results in “direct cell capture” onto the biosensor surface. These specific binding events induce predictable changes in the thin-film optical interference spectrum of the hybrid. Preliminary studies demonstrate the applicability of these biosensors for the detection of low bacterial concentrations in the range of 103–105 cell mL−1 within minutes.

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