DNAzyme-based turn-on chemiluminescence assays in homogenous media

In this work, novel biosensing systems were developed for DNAzyme-based assays in homogenous aqueous media. The two halves of a horseradish peroxidase mimicking DNAzyme were assembled onto different gold nanoparticle surfaces through hybridization with corresponding linking DNA sequences. In the analyses, the target molecules were recognized by the linking DNA. This recognition broke the hybridization and released the DNAzyme halves from the nanoparticle surface into the solution. Together, both the DNAzyme halves combined with a cofactor hemin and turned into a catalytic hemin/G-quadruplex structure, which amplified the luminol oxidation for a turn-on chemiluminescence signaling. Based on this nanoparticle-based DNAzyme-halves design, only low background noise showed up within the homogenous solution and no separation was required in the detection steps. Aptasensor and DNA sensor were developed and analyses of the target molecules adenosine and target DNA were achieved down to 0.7 μM and 0.3 nM respectively with satisfactory selectivity.