Highly sensitive and specific assessment of ochratoxin A in herbal medicines via activator regeneration by electron transfer ATRP

Abstract

Ochratoxin A (OTA) seriously affects the quality of herbal medicines and threatens the health of patients. Therefore, accurate detection of OTA in herbs is of great significance. Here, we fabricated a signal-off fluorescent biosensor for the highly sensitive detection of OTA by the activator regenerated by electron transfer atom transfer radical polymerization (ARGET ATRP) signal amplification technique. First, the specific aptamer sequence was immobilized on carboxylic MBs by an amide reaction. At the same time, the initiator was attached to the cDNA. Then the aptamer and cDNA formed a double helix structure through complementary base pairing. Afterwards, numerous fluorescent monomers were grafted onto the cDNA by ARGET ATRP, which emitted strong fluorescence. Upon addition of OTA, it could be specifically recognized by the aptamer and displace the cDNA, generating fluorescence quenching. Under optimal conditions, the detection limit of the as-prepared sensor was 7.6 fg mL⁻¹ with a detection range of 2 × 10⁻³ ng mL⁻¹ to 2 × 10³ ng mL⁻¹. Furthermore, this sensor exhibited high selectivity and reproducibility, and was successfully applied to the detection of OTA in samples of forsythia, astragalus, licorice, xanthium and malt. The outstanding performance of this biosensor suggests its possible application in the detection of mycotoxin in herbal medicine samples.