A new system for detection of cocaine was designed based on an AIEgen of TPE-TTA, anticocaine aptamer and exonuclease Ⅰ(Exo Ⅰ) . The Exo Ⅰ can specifically cleave the phosphodiester bonds of nucleotides in nucleic acids either from the ends or interior of single stranded DNA(ssDNA). Meanwhile, the cocaine can combine with anticocaine aptamer and switch its configuration to Y-shaped double stranded DNAs(dsDNA) that prevent the aptamer degradation in the presence of Exo Ⅰ. When cationic 4,4',4″,4″'-{[ethene-1,1,2,2-tetrayltetrakis(benzene-4,1-diyl)]tetrakis(oxy)}-tetrakis(N,N,N-triethylbutan-1-aminium) bromide(TPE-TTA) was added to the Tris-HCl solution, it can combine with aptamer and the fluore-scence was turned on. The experiment conditions, including the amount of Exo Ⅰ, incubation time of the Exo Ⅰ with anticocaine aptamer, incubation temperature and time of anticocaine aptamer with cocaine were systematically investigated and the optimal conditions were obtained. With different concentrations of cocaine, the experimental results showed that the fluorescence intensity was progressively enhanced. The limit of detection(LOD) of 0.66 μmol/L was deduced. Moreover, the developed method also was used to determine cocaine in real urine samples, and the LOD can reach as low as 1.0 μmol/L. This work provides a new method for cocaine detection, which is promising for practical application.
