A Resistance Based Biosensor That Utilizes Conductive Microfibers for Microbial Pathogen Detection

Escherichia coli O157:H7 (E. coli O157:H7) is one of the top pathogens of interest for the development of rapid diagnostic systems for food and water samples. The objective of this research is to develop a rapid, novel electrochemical biosensor based on the use of polypropylene microfiber membranes coated with a conductive polypyrrole and antibody functionalized for the biological capture and detection of E. coli O157:H7 in the field. Using glutaraldehyde, pathogen specific antibodies are covalently attached to conductive microfiber membranes which are then blocked using a 5% bovine serum albumin solution. The functionalized membranes are then exposed to E. coli O157:H7 cells washed in Butterfield’s phosphate buffer and added to a phosphate-buffer electrolyte solution. When a voltage is applied to the system, the presence of the captured pathogen on the fiber surface results in an increase in resistance at the electrotextile electrode surface, indicating a positive result. In this study, the initial resistance of the membrane in the electrochemical system was established and found to range between 5.8 kΩ and 13 kΩ. The resistance of the system not associated with the electrotextile fibers was calculated to contribute to only 2.8% of the total system resistance, and found not to be significant. A proof of concept experiment was conducted and determined that the electrotextile electrode was able to differentiate between small changes in a solution’s conductivity associated with the presence of E. coli O157:H7 cells over a concentration range of log 0 9 CFU/mL.