Figure 4

A) Calibration curves of each bacterium at the concentrations of 0.1 nM, 0.5 nM, 1 nM, 5 nM, 10 nM, 50 nM and 100 nM. All curves fitted well logarithmically, with the formulas as follows: y = 0.153 × ln(x) + 0.197, with R² = 0.9991 for P. aeruginosa (blue diamonds); y = 0.121 × ln(x) + 0.103, with R² = 0.9974 for S. aureus (black squares); y = 0.139 × ln(x) + 0.157, with R² = 0.9974 for C. perfringens (red circles); and y = 0.160 × ln(x) + 0.222, with R² = 0.9994 for C. tetani (green triangles). B) Regeneration of the detection with SPR biosensors. Data were expressed as the percentage of maximal SPR degree angle. All the SPR angles decreased with an increase of regeneration. All the SPR angles decreased slightly during the first 100 tests but were still higher than 80%, whereas they dropped rapidly in the another round of 100 tests