Multiplexed Aptasensors and Amplified DNA Sensors Using Functionalized Graphene Oxide: Application for Logic Gate Operations

Graphene oxide (GO) is implemented as a functional matrix for developing fluorescent sensors for the amplified multiplexed detection of DNA, aptamer–substrate complexes, and for the integration of predesigned DNA constructs that activate logic gate operations. Fluorophore-labeled DNA strands acting as probes for two different DNA targets are adsorbed onto GO, leading to the quenching of the luminescence of the fluorophores. Desorption of the probes from the GO, through hybridization with the target DNAs, leads to the fluorescence of the respective label. By coupling exonuclease III, Exo III, to the system, the recycling of the target DNAs is demonstrated, and this leads to the amplified detection of the DNA targets (detection limit 5 × 10–12 M). Similarly, adsorption of fluorophore-functionalized aptamers against thrombin or ATP onto the GO leads to the desorption of the aptamer–substrate complexes from GO and to the triggering of the luminescence corresponding to the respective fluorophore, thus, allowing the multiplexed analysis of the aptamer–substrate complexes. By designing functional fluorophore-labeled DNA constructs and their interaction with GO, in the presence (or absence) of nucleic acids, or two different substrates for aptamers, as inputs, the activation of the "OR" and "AND" logic gates is demonstrated.