Magnetically-assisted impedimetric detection of bacteria using phage-modified carbon microarrays

This study presents an investigation on the possibility of improving the detection limit of bacteria with an inexpensive electrochemical, impedimetric sensor platform, by integrating the sensor with magnetic manipulation. The approach uses T4 bacteriophage coated Dynabeads to selectively capture and concentrate E. coli K12 cells from samples, to increase the sensitivity of detection at the surface of functionalized screen-printed carbon microarrays. Fluorescence and flow cytometry measurements indicate that the surface modification of the magnetic beads, with phages, and binding with the bacteria, were successful. Integration of the screen-printed carbon-based impedimetric sensor, with a magnetic manipulation system, was found to improve the sensitivity of the device, decreasing the limit of detection of E. coli K12 from 104 to 103 cfu/mL. We have also demonstrated that this approach provides for more specific detection of bacteria, enabling the operator to account for non-specific adsorption, and detection of bacteria in more complex (real) samples (milk).