SERS based artificial peroxidase enzyme regulated multiple signal amplified system for quantitative detection of foodborne pathogens

Low-cost and portable detection system for foodborne pathogens is crucial in assurance of food quality and public health. Therefore, a multiple signal amplified system with the advantages of easy operation, multiple signal detection mode and low-cost was developed to detect foodborne pathogens. In this study, Staphylococcus aureus (S. aureus) was selected as detection object to capture by the magnetic probe. Fe-MIL-88 enzyme-catalyzed leuco malachite green (LMG, white color with no SERS signal and absorbance properties) to malachite green (MG, green color with strong SERS signal and UV–Vis absorbance in 620 nm). However, the catalytic activity of the artificial Fe-MIL-88 enzyme was lost after adsorbing S. aureus aptamer. Consequently, a system was built to yield the catalytic product (MG) equivalent to the amount of S. aureus. SERS spectroscopy and spectrophotometer were applied to quantitatively detect S. aureus over the range of 101–106 CFU/mL via detecting the signals of MG. SERS based method contributed a higher correlation coefficient (0.987) and a lower detection limit (1.95 CFU/mL) compared with UV–Vis method. T-test results showed no significant differences between the SERS based method and plate-counting method for detecting the amount of S. aureus, which indicated the proposed method had excellent accuracy to quantify pathogens in real samples.