Numerous species of bacteria pose a serious threat to human health and cause several million deaths annually. It is therefore essential to have quick, efficient, and easily operable methods of bacterial cell detection. Herein, we synthesize a novel cationic covalent organic polymer (COP) named CATN through the Menshutkin reaction and evaluate its potential as an impedance sensor for Escherichia coli cells. On account of its positive surface charge (ζ-potential = +21.0 mV) and pyridinium moieties, CATN is expected to interact favorably with bacteria that possess a negatively charged cell surface through electrostatic interactions. The interdigitated electrode arrays were coated with CATN using a simple yet non-traditional method of electrophoresis and then used in two-electrode electrochemical impedance spectroscopy (EIS) measurements. The impedance response showed a linear relationship with the increasing concentration of E. coli. The system was sensitive to bacterial concentrations as low as 30 CFU mL-1, which is far below the concentration considered to cause illnesses. The calculated limit of detection was as low as 2 CFU mL-1. This work is a rare example of a COP used in this type of bacteria sensing and is anticipated to stimulate further interest in the synthesis of organic polymers for EIS-based sensors.
Bibliografisk noteFunding Information:
The authors thank Claudia Dercole for providing a stock of E. coli DH5α bacterial cells. A.M. and M.V. acknowledge the financial support from the Slovenian Research Agency (research core funding no. P2-0412 and project no. J2-2498).
This project has received funding from the European Union’s Horizon 2020 research and innovation program under the Marie Skłodowska-Curie grant agreement no. 101038091. me