A simple and sensitive fluorescent method for ochratoxin A (OTA) detection was developed based on enzyme-assisted target recycling signal amplification in combination with graphene oxide coating. The poly-vinylpyrrolidone （PVP） was used as coating material to prevent the unspecific adsorption between target and graphene oxide. Optimum detection performance for OTA was obtained when the graphene oxide was 4 μg/mL，the PVP （molecular weight of 24 000）was 10 nmol/L，the activity of DNase Ⅰ was 40 U and the reaction time was 40 min. The results showed that the fluorescence intensities displayed a good linear relationship with the OTA concentrations between 25 nmol/L and 250 nmol/L. The limit of detection (LOD) was 9.38 nmol/L at the signal to noise ratio of 3. The OTA selection specificity of the method was good. Its recovery rates were from 96.78% to 110.97%, and the standard deviations were from 1.23% to 5.00%. It has been verified to be useful for detecting OTA in red wine, white coffee and instant coffee, and could be expected to provide a new idea and platform for the detection of other relevant safety hazard factors in food.

ochratoxin A; graphene oxide; aptamer; DNase Ⅰ; fluorescence detection