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. 2014 Jun 18;86(14):6968–6975. doi: 10.1021/ac500897t

Figure 4.

Figure 4

pH-LAMP optimization. (a) The detection limit of a commercially available E. coli O157:H7 kit is shown. LAMP allows for detection of 100–1000 CFU/reaction in less than 30 min. The inset graph provides the normalized real-time amplification data. (b) The pH-LAMP detection limit is shown. Regardless of starting E. coli concentration, the resulting pH change is consistent at around −0.2 pH units. (c) Reducing the Tris-HCl buffer concentration in the reaction mix increases the pH change associated with amplification. The maximum pH change observed in these tests was −1.2 pH units. (d) Decreasing the isothermal amplification buffer concentration also reduced the ionic strength of the solution. This requires the reaction temperature to be reduced to achieve consistent threshold times. Threshold times were consistent down to 8–12 mM Tris-HCl before significant increases in threshold time are observed.