Homogeneous Electrochemiluminescence Aptasensor Based on Hybridization Chain Reaction and Magnetic Separation Assistance for Staphylococcus Aureus

Staphylococcus aureus(S. aureus) can cause a variety of diseases,so it is essential to provide the simple and responsive identification of bacterial pathogens in clinical treatment. In this work a homogeneous aptamer electrochemiluminescence biosensor for Staphylococcus aureus was developed assisted based on hybridization chain reaction and magnetic separation assistance. The ds (Probe DNA/Aptamer) is modified on the magnetic beads. In the presence of the target the target binds to the Aptamer in ds (Probe DNA/Aptamer) exposing the Probe DNA in the ds DNA. The exposed Probe DNA triggers HCR resulting in long DNA duplexes which can be simply and efficiently enriched for the luminescent molecule Ru(phen)32+. To reduce the possibility of false positive signals Exo III was added to cut unreacted dsDNA from the magnetic beads. The ECL intensity was linearly correlated with the logarithm of S. aureus concentration in the range of 10 CFU/mL -10 x 107 CFU/mL with a detection limit of 3 CFU/mL. The method developed in this work has good sensitivity and specificity and can well evaluate the concentration of Staphylococcus aureus in normal human serum and the results are consistent with the results obtained by the plate counting method.