Dielectrophoresis assisted immuno-capture and detection of foodborne pathogenic bacteria in biochips.

This study integrated dielectrophoresis (DEP) with non-flow through biochips to enhance the immuno-capture and detection of foodborne pathogenic bacteria. It demonstrated two major functions provided by DEP to improve the chip performance: (i) concentrating bacterial cells from the suspension to different locations on the chip surface by positive and negative DEP; (ii) making the cells in close contact with the immobilized antibodies on the chip surface so that immuno-capture efficiency can be dramatically enhanced. The microchip achieved the immuno-capture efficiencies of approximately 56.0% and approximately 64.0% to Salmonella cells with 15 and 30 min DEP, respectively, which were considerably higher than those of approximately 10.4% and approximately 17.6% for 15 and 30 min immuno-capture without DEP. The immuno-captured bacterial cells were detected by the sandwich format ELISA on the chips. The final absorbance signals were enhanced by DEP assisted immuno-capture by 64.7-105.2% for the samples containing 10(3)-10(6) cells/20 microl. The integration of DEP with the biochips has the potential to advance the chip-based immunoassay methods for microbial detection.