Layered molybdenum selenide stacking flower-like nanostructure coupled with guanine-rich DNA sequence for ultrasensitive ochratoxin A aptasensor application

Sensitive detection of ochratoxin A (OTA) plays an important role in the field of food safety control. In this study, we are reporting for the first time an electrochemical biosensor which employs the integration of MoSe 2 nanoflowers , Au nanoparticles (AuNPs), aptamer and the guanine-rich complementary DNA sequence for the sensitive detection of OTA. MoSe 2 nanoflowers are prepared by a simple hydrothermal method and used as a promising sensing platform based on its large surface area. The methylene blue is used as a tracer and a guanine-rich complementary DNA sequence is designed to bind with the unbound OTA aptamer for signal amplification . The aptamer is immobilized on the AuNPs/MoSe 2 modified electrode surface through Au–S interaction. Since OTA can competitively bind with the aptamer due to their high affinity, the presence of OTA will induce the decrease of guanine-rich DNA on the electrode surface , in turn reduces the signal of methylene blue which can specifically adsorb to the guanine units of DNA. The proposed assay shows a good linear relationship within the range of 0.0001–1   nM with a detection limit of 0.08   pM for OTA. The developed biosensor has been applied to determine OTA concentration in wine samples.