Fig. 2. (A) Fluorescence intensity of GO nanoprobes incubated (a) without ATP and without Pb²⁺, (b) without ATP and with Pb²⁺, (c) with ATP and without Pb²⁺, (d) with ATP and with Pb²⁺ after 80 min; (B) PAGE image of (a) S1/S3, (b) S2, (c) S3, (d) S4, (e) mixture of S1/S3, S2, S4 and ATP after incubation for 80 min, (f) mixture of S1/S3, S2, S4, ATP and Pb²⁺ after incubation for 80 min.