Figure 3.

Examination of selectivity. (A) UV–Vis absorption spectra of the samples (0.2 mL) containing E. coli O157:H7, S. aureus, B. cereus, S. pyogenes, and E. faecalis prepared in the phosphate buffer at pH 3; spectra were obtained after reaction with TMB (1.25 mM) in the presence of H₂O₂ (~11.2 mM) for 25 min, followed by the addition of sulfuric acid (2 M, 2 µL) to stop the reaction. All the model bacteria had the cell concentration of OD₆₀₀ equal to ~1. (B) Photograph of the samples (0.2 mL) containing S. aureus, E. coli O157:H7, K. pneumoniae, and P. aeruginosa (from left to right) prepared in the phosphate buffer at pH 3 and obtained after reaction with H₂O₂ (180 mM) for 5 min. All the model bacteria had a cell concentration of OD₆₀₀ equal to ~1.