title: Bare fiber Bragg grating immunosensor for real-time detection of Escherichia coli bacteria.
abstract: Escherichia coli (E. coli) bacteria have been identified to be the cause of variety of health outbreaks resulting from contamination of food and water. Timely and rapid detection of the bacteria is thus crucial to maintain desired quality of food products and water resources. A novel methodology proposed in this paper demonstrates for the first time, the feasibility of employing a bare fiber Bragg grating (bFBG) sensor for detection of E. coli bacteria. The sensor was fabricated in a photo-sensitive optical fiber (4.2 µm/80 µm). Anti-E. coli antibody was immobilized on the sensor surface to enable the capture of target cells/bacteria present in the sample solution. Strain induced on the sensor surface as a result of antibody immobilization and subsequent binding of E. coli bacteria resulted in unique wavelength shifts in the respective recording of the reflected Bragg wavelength, which can be exploited for the application of biosensing. Functionalization and antibody binding on to the fiber surface was cross validated by the color development resulting from the reaction of an appropriate substrate solution with the enzyme label conjugated to the anti-E. coli antibody. Scanning electron microscope image of the fiber, further verified the E. coli cells bound to the antibody immobilized sensor surface.
authors.affiliation: Optics & Microfluidics Instrumentation Lab, Department of Instrumentation and Applied Physics, Indian Institute of Science, Bangalore, 560012, India.
authors.forename: Rajesh
authors.initials: R
authors.lastname: Srinivasan
authors.affiliation: Department of Instrumentation and Applied Physics, Indian Institute of Science, Bangalore, 560012, India.
authors.forename: Sharath
authors.initials: S
authors.lastname: Umesh
authors.affiliation: Optics & Microfluidics Instrumentation Lab, Department of Instrumentation and Applied Physics, Indian Institute of Science, Bangalore, 560012, India.
authors.forename: Swetha
authors.initials: S
authors.lastname: Murali
authors.affiliation: Department of Instrumentation and Applied Physics, Indian Institute of Science, Bangalore, 560012, India.|Applied Photonics Initiative and Robert Bosch Centre for Cyber Physical Systems, Indian Institute of Science, Bangalore, 560012, India.
authors.forename: Sundarrajan
authors.initials: S
authors.lastname: Asokan
authors.affiliation: Optics & Microfluidics Instrumentation Lab, Department of Instrumentation and Applied Physics, Indian Institute of Science, Bangalore, 560012, India.
authors.forename: Sai
authors.initials: S
authors.lastname: Siva Gorthi
mesh_terms: D000907:Antibodies, Bacterial / Q000737:chemistry*; D055910:Antibodies, Immobilized / Q000737:chemistry*; D015374:Biosensing Techniques; D004926:Escherichia coli / Q000302:isolation & purification*; D055100:Optical Fibers
chemical_list: D000907:Antibodies, Bacterial; D055910:Antibodies, Immobilized
keywords: biosensors; fiber optic technology; immunoassay; pathogenesis; quality control