Aptamer-based F0F1-ATPase biosensor for Salmonella typhimurium detection

A novel biosensor was developed by conjugating Salmonella typhimurium aptamer with the “rotator” ε-subunit of F0F1-ATPase within chromatophores through an anti-ε-subunit antibody-biotin-avidin-biotin-aptamer linker to capture bacteria. The bacterial load decreased the rotation rate of F0F1-ATPase, which led to the decrease in ATP synthesis. The detection of S. typhimurium was based on proton flux change driven by the F0F1-ATPase-mediated ATP-synthesis, which was indicated by fluorescence probe, monitored by a fluorescence spectrometer. Under optimal conditions, the correlation between the relative fluorescence signal intensity and the concentration of S. typhimurium was observed to be linear within the range of 101 to 104 cfu·mL−1 (R2 = 0.9944). The limit of detection for S. typhimurium was as low as 10 cfu·mL−1. The results demonstrate that the F0F1-ATPase molecular motor biosensor can specifically detect S. typhimurium at low concentration, and will be a convenient, quick, and promising tool for detecting pathogens.