Fluorescent "turn-on" aptamer sensor for sensitive and reliable detection of Golgi glycoprotein 73 based on nitrogen-doped graphene quantum dots and molybdenum disulfide nanosheets.

The sensitivity and specificity of Golgi glycoprotein 73 (GP73) are very important for early diagnosis of hepatocellular carcinoma. Herein, we constructed a new-fashioned fluorescent aptamer sensor for GP73 determination based on nitrogen-doped graphene quantum dots (N-GQDS) and molybdenum disulfide (MoS2) nanosheets. N-GQDs with high fluorescence intensity and good stability were screened out, and GP73 aptamer (GP73Apt) is labeled with N-GQDs to form the N-GQDs-GP73Apt fluorescence probe. MoS2 nanosheets can quench the fluorescence of N-GQDs-GP73Apt owing to fluorescence resonance energy transfer mechanisms. After introducing GP73 into the biosensing system, the N-GQDs-GP73Apt specifically bound with GP73 to form the deployable structures, making N-GQDs-GP73Apt far away from MoS2, blocking the fluorescence energy transfer process, and restoring the fluorescence of N-GQDs-GP73Apt. When the GP73 concentration was in the extent of 2.5 ng/mL∼100 ng/mL, the relative fluorescence recovery is linearly relevant to the concentration of GP73, and the limit of detection (LOD) was 1.29 ng/mL (S/N = 3). Moreover in the application of actual serum sample detection, the recovery was range 98.85∼100.55 %. The fluorescent aptamer sensor can rapidly detect and analyze the serum marker GP73 with the characteristics of low-cost, high sensitivity, good specificity and recovery.