Issue 24, 2021

Fabrication of bifunctional G-quadruplex-hemin DNAzymes for colorimetric detection of apurinic/apyrimidinic endonuclease 1 and microRNA-21

Abstract

G-quadruplex-based complexes have been widely used in various analytical methods due to their outstanding capabilities of generating colorimetric, fluorescent or electrochemical signals. However, since loop sequences in traditional G-quadruplex structures are quite short, it is difficult to establish biosensors solely using G-quadruplex-based complexes. Herein, we attempted to lengthen the loop sequences of G-quadruplex structures and found that G-quadruplex-hemin DNAzymes (G-DNAzymes) with long loops (even 30 nucleotides) maintain high peroxidase activity. In addition, the peroxidase activity is not affected by the hybridization of the long loop with its complementary counterpart. Consequently, G-DNAzyme can be endowed with an additional function by taking the long loop as a recognition element, which may facilitate the construction of diverse colorimetric biosensors. Furthermore, by designing an apurinic/apyrimidinic site or a complementary sequence of microRNA-21 (miRNA-21) in long loops, bifunctional G-DNAzymes can be split in the presence of apurinic/apyrimidinic endonuclease 1 (APE1) or miRNA-21, decreasing their peroxidase activities. Accordingly, APE1 and miRNA-21 are quantified using 3,3′,5,5′-tetramethylbenzidine as a chromophore. Using the G-DNAzyme, APE1 can be detected in a linear range from 2.5 to 22.5 U mL−1 with a LOD of 1.8 U mL−1. It is to be noted that benefitting from duplex-specific nuclease-induced signal amplification, the linear range of the miRNA-21 biosensor is broadened to 5 orders of magnitude, while the limit of detection is as low as 73 fM. This work demonstrates that G-DNAzymes with long loops can both generate signals and recognize targets, providing an alternative strategy to design G-quadruplex-based analytical methods.

Graphical abstract: Fabrication of bifunctional G-quadruplex-hemin DNAzymes for colorimetric detection of apurinic/apyrimidinic endonuclease 1 and microRNA-21

Supplementary files

Article information

Article type
Communication
Submitted
04 Sep 2021
Accepted
27 Oct 2021
First published
28 Oct 2021

Analyst, 2021,146, 7379-7385

Fabrication of bifunctional G-quadruplex-hemin DNAzymes for colorimetric detection of apurinic/apyrimidinic endonuclease 1 and microRNA-21

X. Huang, Z. He, K. Zhou, H. Zhi and J. Yang, Analyst, 2021, 146, 7379 DOI: 10.1039/D1AN01603B

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