G‐Quadruplex Aptamers with Peroxidase‐Like DNAzyme Functions: Which Is the Best and How Does it Work?

Abstract Select the best: Five G‐quadruplex hemin‐binding aptamers are compared to determine the best candidate for DNAzyme‐based sensing application. The structural model and catalytic mechanism of the hemin–G‐quadruplex complex are proposed to indicate how it works in a manner similar to the peroxidase. magnified image Some G‐quadruplex DNA aptamers have been found to strongly bind hemin to form DNAzymes with peroxidase‐like activity. To help determine the most suitable DNAzymes and to understand how they work, five previously reported G‐quadruplex aptamers were compared for their binding affinity and then the potential catalytic mechanism of their corresponding hemin‐G‐quadruplex DNAzymes was explored. Among these aptamers, a G‐quadruplex named AGRO100 was shown to possess the highest hemin‐binding affinity and the best DNAzyme function. This means that AGRO100 is the most ideal candidate for DNAzyme‐based analysis. Furthermore, we found the peroxidase‐like activity of DNAzyme to be primarily dependent on the concentration of H 2 O 2 and independent of that of the peroxidase substrate (that is, 2,2′‐azino‐bis(3‐ethylbenzothiazoline‐6‐sulfonic acid)diammonium salt). Accordingly, a reaction mechanism for DNAzyme‐catalyzed peroxidation is proposed. This study provides new insights into the G‐quadruplex‐based DNAzymes and will help us to further extend their applications in the analytical field.