(174aq) Robust Aptasensor Design for S. Aureus Detection

Staphylococcus aureus (S. aureus) is one of the major foodborne pathogens that can cause various infections, from minor skin infections to lethal diseases. Iron-regulated surface determinant protein A (IsdA) is an important protein on the S. aureus surface. It is responsible for iron scavenging via interaction with hemoglobin, haptoglobin, and hemoglobin-haptoglobin complexes. This study develops a straightforward portable electrochemical aptasensor for IsdA and S. aureus detection using aptamer-modified gold nanoparticles (AuNPs). The electrode system was made of three parts, including a carbon counter electrode, an AuNPs/carbon working electrode, and a silver reference electrode. The aptamer by Au-S bonding was conjugated on the electrode surface to create the aptasensor platform. Cyclic voltammetry (CV), Differential Pulse Voltammetry (DPV), and Electrochemical Impedance Spectroscopy (EIS) were utilized to investigate the binding interactions between the aptasensor and the IsdA protein. CV curves of the aptasensor device showed a linear correlation between varying S. aureus concentrations within the range of 10 to 10⁶ CFU/mL, resulting in a considerably low limit of detection (LOD). The results demonstrated strong reproducibility, selectivity, and sensitivity of the aptasensor for enhanced detection of IsdA, along with about 93 % performance stability after 30 days. The capability of the aptasensor to directly detect S. aureus via the IsdA surface protein binding was further investigated. Overall, the aptasensor device showed the potential for rapid detection of S. aureus, serving as a robust approach to developing real-time aptasensors to identify an extensive range of targets of foodborne pathogens and beyond.