LAUSR

A sensitive fluorescent DNA hydrogel aptasensor based on the self-assembling of rolling circle amplification (RCA) products was developed for Ochratoxin A (OTA) detection in beer. A competitive binding mode of aptamer, complementary sequence and target was integrated into DNA hydrogel for OTA detection. The OTA aptamer first complementary combined with the primer to form the hybridized product. Then, in the presence of OTA, the aptamer tended to combine with OTA, which would make the primer released. And the released primer could hybridize with the padlock probe to form circular template and RCA reaction would be initiated by adding ligase, polymerase and dNTPs. Fluorescent DNA hydrogel was obtained by adding Cy3-dUTP together with dNTPs, and the fluorescence (FL) intensity of DNA hydrogel was positively correlated with OTA concentration. Under the optimal experimental conditions, the linear range of the relationship varied from 0.05 ng/mL to 100 ng/mL with the detection limit of OTA of 0.01 ng/mL. The fluorescent DNA hydrogel aptasensor showed good specificity and stability in beer samples. Therefore, the fabricated DNA hydrogel aptasensor shows considerable potential applications in detecting OTA in food safety.