Label-free voltammetric detection of E. coli bacteria using carbon paste screen-printed microchips

Abstract In the present study, we developed a rapid and reliable point-of-care voltammetric method for the detection of Escherichia coli (E. coli DH5α strain) bacteria. E. coli was quantified using a carbon paste screen-printed electrode modified with a poly(vinyl alcohol) gel containing a metabolic redox indicator (resazurin). Viable bacterial cells reduce the metabolic redox indicators via respiratory electron transfer reaction in the plasma membrane. Herein, we monitored the consumption of the redox indicator on the electrode surface by differential pulse voltammetry (DPV), every 30 min, in the potential range between 0 and - 0.6 V. This methodology allowed us to gain information on the quantity of viable bacterial cells and their multiplication with time. Analyzed bacterial species could be quantified in the range of 10 to 108 cells/mL and can be employed for diagnosis of blood-stream infections (BSIs) or urinary tract infections (UTIs).