Abstract: In order to quickly and accurately detect the single-base mismatch in the system,using the difference of absorptivity between ssDNA and dsDNA and the excellent fluorescence quenching ability of the oxidized graphene,assorted with comb-type cationic copolymer PLL-g-Dex that produces high nucleic acid companion activity while coordinated with the oxidized graphene,an enzyme-free,accurate and efficient analysis system was established. First,the feasibility of experiment design was confirmed by fluorescence detection. Then in the detection of optimal concentration of every component in the process,it was found that the optimal experimental position occurred when the concentration of T-DNA was 20 nmol/L,GO was 9μg/mL,cDNA was 90 nmol/L,and PLL-g-Dex was 96 nmol/L. Finally,the selectivity of the detection system to single-base mismatch was collaborated,and the results revealed that the fluorescence intensities from different base mismatch systems differed. Moreover,compared to other bases,PLL-g-Dex presented stronger selectivity to C-C base mismatch.

Key words: biosensors, single-base mismatch, DNA, oxidized graphene, PLL-g-Dex