Cascade FRET (Fluorescence Resonance Energy Transfer) aptamer sensor and method for detecting ochratoxin A

The invention discloses a cascade FRET (Fluorescence Resonance Energy Transfer) aptamer sensor and a method for detecting ochratoxin A (OTA). Comprising donor nanoparticles and acceptor nanoparticles; an OTA aptamer (Apt) is modified outside the donor nanoparticles; a complementary chain of the OTA aptamer is modified by the receptor nanoparticles, and the OTA aptamer and the complementary chain are hybridized, so that the receptor nanoparticles can receive fluorescence emitted by the donor nanoparticles; the exterior of the receptor nanoparticle is modified with a receptor fluorophore, so that fluorescence emitted by the receptor nanoparticle can be received, fluorescence emission of the receptor nanoparticle can be realized, and an FRET sensor similar to cascade transfer is formed; due to the existence of OTA, hybridization dissociation of an aptamer and a complementary chain is achieved, so that fluorescence of the donor nanoparticles cannot be transmitted to the receptor nanoparticles, and a receptor fluo