A Target-Responsive Electrochemical Aptamer Switch (TREAS) for Reagentless Detection of Nanomolar ATP

In this communication, we report a highly generalizable strategy, target-responsive electrochemical aptamer switch (TREAS) for the development of aptamer-based biosensors. In a typical TREAS design for ATP detection, the aptamer oligonucleotide dually labeled with thiol and ferrocene groups is hybridized with its complementary strand, and the thiolated duplex is self-assembled on a gold electrode. This duplex is responsive to the target ATP, which liberates the complementary strand and forms the aptamer−target complex. The electroactive ferrocene moiety, which is distal to the electrode surface in the absence of ATP, is moved to the proximal position during the binding-induced structural transition. This binding turns on the electron transfer and leads to measurable electrochemical signals for quantification of ATP. We then demonstrate that TREAS is a signal-on, reagentless sensor that can selectively detect ATP and features both generalizability and simplicity in design.