Aptamer Immobilized Magnetoelastic Sensor for the Determination of Staphylococcus aureus

An aptamer-based magnetoelastic sensor for the determination of Staphylococcus aureus is reported. Aptamers specific to S. aureus were used to ensure specific and selective binding of bacteria on the sensor surface. The sensors were exposed to S. aureus concentrations of 1 × 10¹–1 × 10¹¹ colony forming units per milliliter, and the changes in resonance frequency were monitored. The sensitivity was higher for sensors with smaller physical dimensions. The biosensor with dimensions of 2 × 5 × 0.028 millimeters provided a linear dynamic range of 10¹–10¹¹ colony forming units per milliliter and a detection limit of 5 colony forming units per milliliter. The results also demonstrated that the magnetoelastic sensors determined the targeted pathogenic species with good selectivity. The method was employed to determine S. aureus in water, and the results were comparable to those obtained by plate-counting methods. The high sensitivity, selectivity, and stability of the aptamer provide a promising approach for the determination of pathogenic bacteria.