Label-free and selective bacteria detection using a film with transferred bacterial configuration

Specific identification of bacteria has been achieved through precisely transferred bacterial structure on the surface of overoxidized polypyrrole (OPPy) film. The recognition of target bacteria was successfully carried out in real time using OPPy film in combination with dielectrophoresis. The unique combination of both techniques made the specific detection of template bacilli possible at concentrations as low as 10(3) CFU/mL within 3 min, without any bacterial pretreatment. The observation of the movement of bacteria by using a fluorescent microscope revealed that living bacteria were being trapped vertically in the cavity created in the OPPy film. Further, the bacterial cavities had high selectivity and were able to discriminate particular target bacteria, Pseudomonas aeruginosa, out of bacterial mixtures containing Acinetobacter calcoaceticus, Escherichia coli, and Serratia marcescens, which are known to have a similar shape. This simple method can be used for a wide variety of applications in which rapid bacterial detection is required, such as food safety risk assessment, clinical point-of-care testing, and continuous environmental monitoring.