Fig. 3.

Two-input AND logic gated cellular biosensors. (A) The arsenite and mercury sensitive AND logic gated sensor was measured using 81 combinations of the two input metals (0, 0.125, 0.25, 0.5, 1.0, 2.0, 4.0, 8.0, 16.0 μM arsenite by 0, 0.0625, 0.125, 0.25, 0.5, 1.0, 2.0, 4.0, 5.0 μM mercury). (B) The 3OC₆HSL and copper sensitive AND logic gated sensor was measured using 72 combinations of two input chemicals (0, 0.39, 1.56, 6.25, 25.0, 50, 100, 400 nM 3OC₆HSL by 0, 0.00137, 0.0041, 0.0123, 0.037, 0.11, 0.33, 1.0, 2.0 mM CuSO₄). (C) The AND logic gated zinc sensor was measured using various levels of ZnCl₂ or PbCl₂ (0, 0.0041, 0.0123, 0.037, 0.111, 0.222, 0.333, 0.5, 0.75, 1, 1.2 mM) or CdCl₂ (0, 0.00137, 0.0041, 0.0123, 0.037, 0.111, 0.222, 0.333, 0.4 mM). (D) Behaviour of the AND gated sensor for arsenic and mercury (Fig. 3A) in the presence of other competing metals. The sensor responses are assayed under four logic combinations of the two target metal ions (16 μM NaAsO₂ plus 2 μM HgCl₂, 16 μM NaAsO₂ only, 2 μM HgCl₂ only, and no target metals) either in the absence of other metals (Pure) or in the presence of two other competing chemicals with each metal added at 0.1 mM and 3OC₆HSL at 100 nM. Error bars, s.d. (n=4). In A and B, all data are the average of three repeats with variations less than 10% between biological replicates.