Inhibited aptazyme-based catalytic molecular beacon for amplified detection of adenosine

Combining the inhibited aptazyme and molecular beacon (MB), we developed a versatile sensing strategy for amplified detection of adenosine. In this strategy, the adenosine aptamer links to the 8-17 DNAzyme to form an aptazyme. A short sequence, denoted as inhibitor, is designed to form a duplex spanning the aptamer-DNAzyme junction, which blocks the catalytic function of the DNAzyme. Only in the presence of target adenosine, the aptamer binds to adenosine, thus the inhibitor dissociates from the aptamer portion of the aptazyme and can no longer form the stable duplex required to inhibit the catalytic activity of the aptazyme. The released DNAzyme domain will hybridize to the MB and catalyze the cleavage in the presence of Zn²⁺, making the fluorophore separate from the quencher and resulting in fluorescence signal. The results showed that the detection method has a dynamic range from 10 nmol/L to 1 nmol/L, with a detection limit of 10 nmol/L.