Portable detection of Staphylococcus aureus using personal glucose meter based on hybridization chain reaction strategy

Staphylococcus aureus is one of the most important food-borne bacterial pathogens and causes numerous illnesses. In this work, we report a sensitive and highly selective magnetic-aptamer biosensor based on a personal glucose meter (PGM) platform for the detection of Staphylococcus aureus. The aptamer for Staphylococcus aureus was immobilized on the magnetic bead by hybridization with the capture probe P. In the presence of Staphylococcus aureus, the aptamer was dissociated from the magnetic bead. Then the capture probe was exposed and could be hybridized with a biotinylated probe to trigger the DNA hybridization chain reaction (HCR), thus achieving the signal amplification. The concentration of streptavidin-labeled invertase can be read by PGM, thus can lead to the portable quantitative detection of Staphylococcus aureus. After optimization of various conditions, 5 mu M probe P, the MB-P reaction time for 36 h, the competition time for 60 min, 0.5 mu M H1 & H2, 0.5 M sucrose and the sucrose invertase catalytic reaction time for 50 min was chosen to achieve the better sensor performance. Under the optimal conditions, the fabricated sensor offers high sensitivity with the limit of detection about 2 CFU/mL. This sensitive PGM based sensor could successfully evaluate the Staphylococcus aureus concentration in real food samples, and the results are consistent with those obtained by using plate counting methods. Moreover, the PGM sensor can greatly reduce the required time compared to the plate counting methods. The fabricated sensor supplies an ideal solution for rapid portable detection of bacterial pathogens and holds its potential use in the quality control for agriculture and food enterprises, entry-exit inspection and quality testing for food.