Fig. 5.
Using the Parabola Principle to design visible qualitative Hg (II) biosensors. a Parabola of the merR biosensors incubated with 0.25 μmol/L of Hg (II). b The performance of biosensor P429-merR in ultrapure water, natural lake water, and polluted water. c Naked eye observation of biosensor P429-merR incubated with Hg (II) solutions