A novel electrochemical DNA biosensor based on HRP-mimicking hemin/G-quadruplex wrapped GOx nanocomposites as tag for detection of Escherichia coli O157: H7

作者：Li Y; Deng J; Fang L; Yu K; Huang H; Jiang L; Liang W^*; Zheng J

来源：Biosensors and Bioelectronics, 2015, 63: 1-6.

DOI：10.1016/j.bios.2014.07.012

• DNA biosensor
• DNAzyme
• Escherichia coli O157:H7
• G-quadruplex
• Graphene oxide

A novel sensitive electrochemical DNA biosensor was developed for amperometric detection of Escherichia coli O157:H7 (E. coli O157:H7). The graphene oxide (GOx) was utilized as nanocarrier to immobilize thionine (Thi) and the Au nanoparticles coated SiO2 nanocomposites (Au-SiO2) by electrostatic adsorption and the adsorption among nanomaterials. Then a large amounts of signal DNA (S2) and G-quadruplex were immobilized on the GOx-Thi-Au@SiO2 nanocomposites. Finally, hemin was intercalated into the G-quadruplex to obtain the hemin/G-quadruplex structure as HRP-mimicking DNAzyme. On the basis of the signal amplification strategy of GOx-Thi-Au@SiO2 nanocomposites and DNAzyme, the developed DNA biosensor could respond to 0.01nM (S/N=3) with a linear calibration range from 0.02 to 50.0nM E. coli O157:H7, which could be well accepted for early clinical detection. The studied system provides new opportunities, and might speed up disease diagnosis, treatment and prevention with pathogen.