Electrochemical response of acridine orange in bacterial cell

Abstract

Fluorescent dye is a useful tool in qualitative analysis. Acridine orange (AO) is one such dye, which fluoresces when bound to biomolecules. In this study, we investigated whether the electrochemical activity of AO can be used for bacterial quantification. We observed that the oxidation peak current of AO depended on the amount of AO-labeled bacteria present on the electrode. The electrochemical response was estimated as 8.4 × 10-15 A for a single cell. In addition, it was found that the response obtained in a dead bacterium was 3 times larger than that obtained in a living cell. We concluded that the difference in the electrochemical response is dependent on the biological functions such as metabolism, respiration, and viability of bacteria.