アカデミックプラザ2013

研究概要

Nano/Microwire-Based Electrochemical Biosensor for Rapid Detection of Foodborne Pathogens

研究機関名

University of Hawaii, USA

代表者

Dr. Soojin Jun

本研究の主旨

Label-free biosensor based on electrochemical impedance measurement followed by dielectrophoretic (DEP) force and antibody-antigen interaction was developed for detection and quantification of foodborne pathogenic bacteria. In this study, gold-tungsten wires (25 µm in diameters) were functionalized by successively coating with polyethyleneimine, streptavidin, and anti-E. coli antibodies to improve the sensing specificity. The focus of this research was to evaluate the performance of the developed biosensor by monitoring the changes of electron-transfer resistance (∆Ret) of the microwire after the bioaffinity reaction between bacterial cells and antibodies on the wire surface, as an alternative to fluorescence microscopic technique. Electrochemical impedance spectroscopy (EIS) were used to detect and validate the resistance changes in a conventional three-electrode system in which [Fe(CN)63-]/[Fe(CN)64-] served as the redox probe. The impedance data demonstrated a linear relationship between the increments of ∆Ret and the concentrations of E. coli suspension in the range of 102 to 108 CFU/mL. The detection limit of the proposed sensor determined by EIS was about 5 cells per wire per sample volume. In addition, the developed sensor shows higher ∆Ret for E. coli (2066.5 Ω) than Salmonella (126.5 Ω), indicating enhanced sensing specificity. Therefore, the electrochemical impedance measurement was expected to be an ideal alternative to fluorescence intensity based quantification for enumeration of bacterial cells captured on the microwire biosensor. Ongoing studies include multiplexed microwire sensors for simultaneous detection and quantification of various food pathogens in food systems.

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