Smartly coupling exonuclease-induced target recycling signal amplifications with β-cyclodextrin host-guest recognition, a novel “signal-on” aptamer sensor for sensitive determination of ochratoxin A (OTA) was proposed for the first time. Firstly, the formation of double-strand DNA (dsDNA) was occurred by hybridizing OTA aptamer with its complementary DNA (cDNA) and as the probe DNA the cDNA at its 3′ terminal was labeled with methylene blue (MB). Next, when OTA was present, the aptamer tended to form aptamer-OTA complex with conformation of...