A general strategy to create RNA aptamer sensors using "regulated" graphene oxide adsorption

Aptamers have been used as molecular recognition elements for sensor development in combination with graphene oxide (GO), a nanomaterial with properties including fluorescence quenching, and selective adsorption of single-stranded nucleic acids. However, previous sensor designs based on aptamer-GO adsorption have not demonstrated wide applicability, and few studies have explored the potential of RNA aptamers. Herein, we present a new sensing strategy based on "regulated" GO adsorption that can accommodate various RNA aptamers. First, adsorption of a fluorophore-labeled RNA aptamer to GO results in fluorescence quenching due to close proximity of the fluorophore to GO. The addition of a complementary, "blocking" DNA strand (BDNA) that hybridizes to the 3'-end of the aptamer, weakens aptamer-GO interaction, and enables increased fluorescent signal generation upon the addition of target, as the sensing system becomes completely separated from GO. Our findings can be applied toward different aptamers, and adapted to enhance generality of existing sensing applications.