Cationic Covalent Organic Polymer Thin Film for Label-free Electrochemical Bacterial Cell Detection.

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 through the Menshutkin reaction and evaluate its potential as an impedance sensor for cells. On account of its positive surface charge (ζ-potential = +21.0 mV) and pyridinium moieties, is expected to interact favorably with bacteria that possess a negatively charged cell surface through electrostatic interactions. The interdigitated electrode arrays were coated with 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 . The system was sensitive to bacterial concentrations as low as ∼30 CFU mL, which is far below the concentration considered to cause illnesses. The calculated limit of detection was as low as 2 CFU mL. 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.