Enzyme-amplified electronic logic gates based on split/intact aptamers.

A series of enzyme-amplified electronic logic gates (OR, AND, NOR, and NAND) for one-spot simultaneous monitoring of small molecules and proteins has been constructed at the molecular level. This simple but universal system is based on target-induced self-assembly of split aptamer fragments or target-induced conformational changes of intact aptamers. For the OR and AND logic operations, the split aptamer fragments were used as the molecular recognition components, while for the NOR and NAND logic operations, the intact aptamers were used as the molecular recognition components. Using ATP and thrombin as inputs, the split/intact aptamers as molecular recognition elements, biotin as a tracer, and SA-HR as a reporter molecule, the electronic logic operations can be easily realized by generating amplified current signals as outputs. The logic system is robust and can be applied to human serum samples with excellent selectivity. Importantly, the reversibility of these logic gates makes the electronic system feasible to perform the set-reset function. Our work not only provides a "smart" and flexible logic platform for ATP and thrombin sensing, but also can be expanded for other ligands assay, such as adenosine monophosphate (AMP), theophylline, and cocaine, by rationally splitting their aptamer sequences into two fragments.