Paper-based and chemical-free dual low-cost electrochemical biosensor for rapid detection of Escherichia coli O157:H7.

A low-cost electrical assay is reported using a paper-based electrochemical biosensor modified with carboxylated graphene oxide (GO-COOH), which is capable of directly immobilizing antibodies without chemical cross-linkers and is promising for the rapid detection of Escherichia coli (E. coli) O157:H7 in low-income areas. Antibodies were immobilized on the surface of the GO-COOH/C electrode at appropriate concentrations to directly and specifically capture targets. The GO-COOH/C paper-based electrochemical biosensor was capable of detecting as low as 0.26 CFU/mL of E. coli O157:H7 within 16 s selectively. The practicality of the GO-COOH/C paper-based electrochemical biosensor was evaluated using tap and river water samples. The detection results were similar to those of the standard plate culture method, but the analysis speed is much faster and has good cost-effectiveness (about US$ 1.81). The GO-COOH/C paper-based electrochemical biosensor stands out among various analytical techniques due to its dual low-cost advantages and excellent detection capabilities for E. coli O157:H7, which provide a strong guarantee for water quality safety in low-income areas.