Microfluidic based Biosensor Platform for Escherichia Coli Detection by Embedding Antimicrobial Peptide-Labeled Beads

Abstract

Many of E. coli assays utilize antibodies for detection, identification, and quantification of foodborne pathogens. Antibody-based assays are a very useful tool to detect specific pathogens due to the specificity of antibodies for specific antigenic sites on the target pathogens [1]. Note that at least one pair of antibodies is required for each target one. In order to overcome this restriction, the antimicrobial peptides (AMPs) magainin I are applied here among the alternative recognition molecules, which is known to have ability effectively binding to multiple target microbes [2]. We develop the unique biosensing platform to detect E. coli DH5α by using a PDMS microfluidic chip designed with a weir space inside the channel, in which AMP-labeled beads are embedded, instead of antibodies. E. coli was stained with propidim iodide, and then we characterized the capturing rate on the surface of AMP-labeled beads to demonstrate the enrichment and detection performance of E. coli. The accumulative fluorescence intensity per unit bead increases, for the conditions of different flow rates ranging from 0.04 to 2.2 μL/min and concentrations (8×102-8×105 cells/mL) of E. coli. The saturation of capturing was entirely observed within 60 min. It should be pointed out that our results provide the potential application of semi-selective AMPs to the fine detection (less than 104 cells/mL) of various non-pathogenic E. coli cells.