An electrochemical and colorimetric dual-mode aptasensor for Staphylococcus aureus based on a multifunctional MOF and magnetic separation technique

Staphylococcus aureus (S. aureus) is a widespread pathogenic bacterium, causing foodborne disease and posing threat to public safety. Thus, it is of great importance for rapid and effective determination of S. aureus. In this protocol, we synthesized a smart DNA-modified Au/CuMOF bioconjugate material (ssDNA-Au/CuMOF) with multiple functions of biorecognition, electrochemical and catalytical activity, and explored its application in dual-mode determination of S. aureus. Magnetic bead (MB) modified with aptamers (MB-Apt) was employed for specific S. aureus capture. The incubation of ssDNA-Au/CuMOF and MB-Apt with different concentration of S. aureus led to the difference in quantity of ssDNA-Au/CuMOF confined on MB or released in supernatant. After magnetic separation, dual-mode detection was realized by the electrochemical measurement and the material-catalyzed colorimetry. This method demonstrated a satisfied analytical performance with a broad linear range from 10 to 108 CFU mL−1, a colorimetric minimum resolution as low as 48 CFU mL−1, an electrochemical detection limit of 5 CFU mL−1, and good selectivity in distinguishing target from non-target bacteria. Its application in detecting S. aureus in complex samples also showed good response, indicating the great potential for S. aureus detection in real samples and providing a methodological and technical support for food monitoring.