An ultra-sensitive electrochemical aptasensor detection for di(2-ethylhexyl) phthalate based a cleavage effect of Mg2+-driven bipedal DNA walker motor

An electrochemical aptamer sensing platform with a cleverly applied Mg2+-DNAzyme driven bipedal DNA walker amplification strategy was constructed for the sensitive detection of di(2-ethylhexyl) phthalate (DEHP). In vitro, due to the specific recognition of DEHP with the aptamer, the bipedal DNA walker motor formed by HP1HP2 duplex is in a free state, making it easier to move and recognize on sensor interface modified with AuNRs/ PEI-rGO. This not only improves the spatial limitations of fixed DNA walker motor, but also has higher recognition efficiency compared to single legged walker motor. In the presence of Mg2+, the bipedal DNA walker motor continuously binds and cleaves at ribonucleotide (rA), causing a large number of signal probes to detach from the sensing interface. The uniformly sized gold-platinum core-shell nano-flower (Pt@AuNFs) as signal probe materials bound numerous thionin (Thi) to obtain stronger signals. As the signal probe is exposed, it causes significant changes in the signal. After the measurement of DEHP in different concentrations, the proposed aptasensor was verified with a low limit of detection (LOD) of 5.2 x 10-5 ng/mL and a wide detection range of 5 x 10-4 to 1 x 103 ng/mL. In addition, excellent specificity, reproducibility, and stability were proved to be the sensor's properties under optimal conditions. Meanwhile, the recoveries obtained from milk samples made the aptasensor eligible to be promoted.