Label-free detection of Escherichia coli bacteria by cascaded chirped long period gratings immunosensor

Kaushik, Siddharth and Tiwari, Umesh and , Nileema and , Shivendu and Das, Bhargab and Sinha, Ravindra K. (2019) Label-free detection of Escherichia coli bacteria by cascaded chirped long period gratings immunosensor. Review of Scientific Instruments, 90 (2). 025003.

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An optical fiber based immunosensing platform formed by two identical chirped long period gratings (CLPGs) for sensitive and label-free detection of Escherichia coli (E. coli) is presented. The proposed immunosensor having two CLPGs with an inter-grating space (IGS) works like a Mach-Zehnder interferometer. The important feature of this sensor is that by changing the refractive index (RI) induced phase at the IGS region, a corresponding shift in resonance wavelength can be realized without affecting the actual grating region. Additionally, the confining bandwidth of the interference fringes promotes greater resolution in the resonance wavelength analysis of the transmission spectrum. The main aim of this study was the specific and rapid detection of the E. coli bacteria in phosphate buffer saline (detection range: 10 cfu/ml to 60 cfu/ml) by using the bio-functionalized IGS region as a sensing probe of the dual CLPG structure. The observed detection limit was 7 cfu/ml. For specificity analysis, Salmonella typhimurium and Staphylococcus aureus were tested and no significant shift in resonance wavelength was observed. In addition, the proposed immunosensor has the ability to selectively detect E. coli in real samples including lake water. The high specificity, good sensitivity to ambient RI, and robustness of the developed sensing platform will open a new avenue in optical immunosensing technology, and cascaded long CLPG sensors can contribute significantly to the detection of pathogenic bacteria in water and food samples.

Item Type: Article
Uncontrolled Keywords: Immunosensing,Chirped,Interferometer
Subjects: CSIO > Chemistry
CSIO > Photonics Instrumentation
Depositing User: Ms T Kaur
Date Deposited: 26 Feb 2020 14:01
Last Modified: 26 Feb 2020 14:01

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