Fluorometric determination of Vibrio parahaemolyticus using an F 0 F 1 -ATPase-based aptamer and labeled chromatophores.

An F0 F1 -ATPase-based aptasensor is described for the fluorometric determination of Vibrio parahaemolyticus. Chromatophores containing F0 F1 -ATPases were first prepared from Rhodospirillum rubrum cells. Then, an aptamer-functionalized chromatophore acts as the capture probe, and a chromatophore labeled with the pH probe fluorescein acts as the signalling probe. In the presence of V. parahaemolyticus, the rotation rate of F0 F1 -ATPase is decreased due to the formation of the aptamer-chromatophore complex. This leads to a retarded proton flux out of the chromatophores. As a result, the pH value inside the chromatophores is reduced, and the fluorescence of the pH probe F1300 is accordingly decreased. The relative fluorescence varies linearly over the 15 to 1.5 × 106  cfu·mL-1 Vibrio parahaemolyticus concentration range, and the limit of detection is 15 cfu·mL-1 . The method was applied to analyze artificially contaminated salmon samples where it showed excellent perfomance. Graphical abstract In this assay, aptamer functionalized chromatophores act as a capture probe, and the fluoresce in labeled chromatophores as signalling probe. The formation of aptamer-chromatophore complex leads to a retarded proton flux out of the chromatophores. As a result, the pH value inside the chromatophores is reduced, and fluorescence intensity is accordingly decreased.