▎ 摘　　要

We report the effect of electrochemical anodization on the properties of monolayer graphene as the main aim of this research and consequently using the resulting label-free impedimetric biosensor for DNA sequences detection. Monolayer graphene was grown by chemical vapor deposition (CVD) with methane as precursor on copper foil, transferred onto a glassy carbon electrode and electrochemically anodized. Raman spectroscopy and X-Ray photo electron spectroscopy revealed enhancement of defect density, roughness and formation of C-O-C, C-O-H and C=O functional groups after anodization. Amine-terminated poly T probe was linked covalently to the carboxylic groups of anodized graphene by the zero-length linker to fabricate the impedance-based DNA biosensor. The anodized graphene electrode demonstrated a superior performance for electrochemical impedance detection of DNA. The DNA biosensor showed a large linear dynamic range from 2.0x10(-18) to 1.0x10(-12)M with a limit of detection of 1.0x10(-18)M using electrochemical impedance spectroscopy (EIS) method. Equivalent circuit modeling shows that DNA hybridization is detected through a change in charge transfer resistance.