Fig. 4
a Raman spectra of E. coli O157:H7 at different concentrations (5 ~ 5 × 105 CFU mL− 1); b The linear relationship between E. coli O157:H7 concentration and Raman intensity at 1621 cm− 1; c Linear analysis of E. coli O157:H7 detection by traditional SERS tag (blue) and CDNA SERS tags (orange); d Specificity evaluation of the SERS platform, only E. coli O157:H7 generated obvious Raman signal; e SERS intensity between E. coli O157:H7 and other complicated bacteria samples, the amount of other pathogens was ten times that of E. coli O157:H7; f The Raman intensity of 20 randomly selected SERS spectra acquired from the measurements for 5 × 105 CFU/mL of E. coli O157:H7.