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Title: Food pathogen detection using Ag nanorod-based surface plasmon resonance sensor

Author
item FU, JUNXUE - Hong Kong University Of Science
item Park, Bosoon
item ZHOA, YIPING - University Of Georgia

Submitted to: Biosensors World Congress
Publication Type: Abstract Only
Publication Acceptance Date: 1/20/2010
Publication Date: 5/26/2010
Citation: Fu, J., Park, B., Zhoa, Y. 2010. Food pathogen detection using Ag nanorod-based surface plasmon resonance sensor. Biosensors World Congress.

Interpretive Summary: n/a

Technical Abstract: Food safety is world-wide issue for protecting public health. Many researchers have been working on development of biosensors for pathogenic bacteria detection. However, current biosensing methods and techniques do not meet the requirement of demanding as a biosensor in terms of sensitivity, specificity and speed for food safety applications. Recently, several studies have shown nanotechnology has the potential for detecting pathogenic bacteria. The conventional thin metal film based surface plasmon resonance (SPR) sensing technique has been used for bacteria detection for decade. In this study, Ag nanorod mediated SPR sensor is first investigated using four-layer Fresnel equations and an effective medium theory. Due to the coupling between the surface plasmon in thin metal film and the localized surface plasmon in Ag nanorod, the nanorod mediated SPR sensor presented a larger resonance angle shift and the sensitivity increased with increasing refractive index of the target analyte. Consequently, SPR properties can be enhanced for detecting pathogenic bacteria. In this paper, optical properties as well as dynamic range and sensitivity enhancement of Ag nanorod mediated SPR sensor are discussed. In addition, experimental data by measuring the SPR signals from Ag film and Ag nanorods/film structures are compared with the results of theoretical analysis. Due to the anisotropic property of the nanorods, the SPR resonance angles are relying on the measurement orientation. Compared with conventional Ag thin film of 40-nm thickness, Ag nanorod of 200-nm with 40-nm Ag film presented a larger SPR angle and narrower width, resulted in a higher Q-factor.