Reducing background signal of G-quadruplex–hemin DNAzyme sensing platform by single-walled carbon nanotubes

The G-quadruplex–hemin DNAzyme has shown potential as a new catalytic label for the development of various biosensors. But the typical problem of high background induced by excess hemin itself limits the application of the method. In this work, we found that single-walled carbon nanotubes (SWNTs) can effectively decrease the background of G-quadruplex–hemin DNAzyme sensing platform. The method relies upon the strong affinity of SWNTs with hemin. In the presence of SWNTs, superfluous hemin is arrested the surface of SWNTs, and then is removed though centrifugation It was proved that SWNTs reduce the background of G-quadruplex–hemin DNAzyme sensing platform by ABTS–H2O2 colorimetric. Moreover, we detected K+ with the AGRO100 as the sensing element. The present limit of detection for K+ is 2 nM, and the sensitivity for analyzing K+ is improved by about 10-fold as compared with the reported colorimetric counterpart in the absence of SWNTs.