Flow-through electrochemical immunoassay for targeted bacteria detection

This study describes a new electrochemical immunoassay for targeted detection of bacteria that can support a new generation of portable bacteria biosensors for field use. The new assay uses a flow-through detection cell that is composed of a syringe filter holder and a filtration membrane. All the steps of the immunoassay are performed inside the flow-through detection cell except for the electrochemical detection step that is performed onto a screen-printed electrode. Disposable syringes are used to add the sample and the reagents of the assay into the flow-through detection cell. On contrary to other assays, that typically analyze less than 0.5 mL of sample, the proposed assay can analyze much higher sample volumes (theoretically any sample volume). In this study 10 mL samples were analyzed. As a proof-of-concept, a flow-through electrochemical immunoassay for the detection of E. coli ORN 178 was developed and tested into the analysis of water and apple juice samples spiked with bacteria. The assay was able to detect bacteria in concentration levels down to 50 CFU/mL in about 2 h. The performance of the assay in terms of accuracy, precision, sensitivity, and selectivity were tested and found satisfactory.