Highly sensitive detection of ochratoxin A by fluorescence polarization assay based on rolling circle amplification

Sensitive and highly selective analysis of ochratoxin A (OTA) plays an important role in food safety. In this paper, an aptamer sensing system based on rolling circle amplification (RCA) technology is proposed for the ultrasensitive fluorescence polarization detection of OTA. The binding of OTA to its aptamer releases the primer S, which rapidly hybridizes with the dumbbell-shaped ring template (HH) to initiate RCA. The effects of the complementary strand length, the hybridization ratio of aptamer (AP) to primer S, the target recognition time, and the reaction temperature on the sensing performance were systematically investigated. Under the optimal experimental conditions, this sensing method demonstrated a well-defined linear relationship with OTA concentrations ranging from 1 × 10^-4 to 10 ng/mL, with a detection limit of 0.032 pg/mL. The developed assay was applied to OTA detection in different samples. These results clearly highlight the potential of the aptamer sensing system for food safety monitoring.