A colorimetric Boolean INHIBIT logic gate for the determination of sulfide based on citrate-capped gold nanoparticles

Herein, we designed a noncommutative logic gate (INHIBIT gate) by utilizing citrate-capped AuNPs as a signal transducer and S2- and TU as mechanical activators and devised a colorimetric sensor for inexpensive, label-free, rapid, sensitive and selective determination of S2-. Under the optimum conditions, 4 mu M S2- could induce a significant color change which can be directly recognized by naked eyes. The calibration curve for the absorbance ratios of A(680)/A(520) against S2- concentration was linear in the range from 2 to 9 mu M and the RSD was 1.3% for the determination of 4 mu M S2- (n = 6). Moreover, this logic gate was successfully applied for sensing S2- in various practical samples, implying its wide applications in food, environment, and biological system.