A multifunctional micro-fluidic system for dielectrophoretic concentration coupled with immuno-capture of low numbers of Listeria monocytogenes

Liju Yang, Biomanufacturing Research Institute & Technology Enterprise,
Padmapriya P. Banada, Department of Food Science, Purdue University
Nigannad R. Chatni, Birck Nanotechnology Center, Bindley Bioscience Center, School of Electrical and Computer Engineering, Purdue University
Kwan Seop Lim, Birck Nanotechnology Center, Bindley Bioscience Center, School of Electrical and Computer Engineering, Purdue University; ERC for Advanced Bioseparation Technology, Inha University
Arun K. Bhunia, Weldon School of Biomedical Engineering, Purdue University
Michael R. Ladisch, Department of Agricultural and Biological Engineering, Weldon School of Biomedical Engineering, Purdue University
Rashid Bashir, Birck Nanotechnology Center, Bindley Bioscience Center, School of Electrical and Computer Engineering, Weldon School of Biomedical Engineering, Purdue University

Date of this Version

June 2006

Citation

DOI: 10.1039/b607061m

This document has been peer-reviewed.

 

Abstract

In this study, we demonstrated a micro-fluidic system with multiple functions, including concentration of bacteria using dielectrophoresis (DEP) and selective capture using antibody recognition, resulting in a high capture efficiency of bacterial cells. The device consisted of an array of oxide covered interdigitated electrodes on a flat silicon substrate and a y16 mm high and y260 mm wide micro-channel within a PDMS cover. For selective capture of Listeria monocytogenes from the samples, the channel surface was functionalized with a biotinylated BSA– streptavidin–biotinylated monoclonal antibody sandwich structure. Positive DEP (at 20 Vpp and 1 MHz) was used to concentrate bacterial cells from the fluid flow. DEP could collect y90% of the cells in a continuous flow at a flow rate of 0.2 ml min21 into the micro-channel with concentration factors between 102–103, in sample volumes of 5–20 ml. A high flow rate of 0.6 ml min21 reduced the DEP capture efficiency to y65%. Positive DEP attracts cells to the edges of the electrodes where the field gradient is the highest. Cells concentrated by DEP were captured by the antibodies immobilized on the channel surface with efficiencies of 18 to 27% with bacterial cell numbers ranging from 101 to 103 cells. It was found that DEP operation in our experiments did not cause any irreversible damage to bacterial cells in terms of cell viability. In addition, increased antigen expression (antigens to C11E9 monoclonal antibody) on cell membranes was observed following the exposure to DEP.

 

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