Electroluminescence aptasensor based on tetrahedral DNA nanostructure with exonuclease-assisted target cycling for detection of acetamiprid.

In this study, an electroluminescent (ECL) aptasensor that could efficiently and sensitively detect acetamiprid (ACE) in vegetables was constructed based on an exonuclease-assisted target cycling amplification strategy. Bimetallic RuZn-based metal-organic framework (RuZn-MOF), nucleic acid exonuclease VII (Exo VII) and tetrahedral DNA nanostructure (TDN) were used as constituent materials. First, RuZn-MOF was a substrate material with good luminescence performance and was synthesized by a hydrothermal method. Second, TDN was autonomously assembled by an adapted single-step annealing way. In this experiment, an aptamer labeled with ferrocene (Fc) at one end was firstly bound to the tip of TDN. In the presence of the target pesticide of ACE, the stronger affinity of ACE for the aptamer made the aptamer and ACE bind preferentially. At the same time, Exo VII was activated to cleave the single-stranded aptamer, resulting in ACE release and Fc detachment. As a result, Fc moved away from the electrode surface, allowing the ECL signal intensity to be restored. The limit of detection (LOD) (33.33 fg/mL) of this method was lower than those of many reported aptasensors. This strategy provides an uncomplicated and responsive technique for the detection of ACE and offers further development possibilities for detection and analysis of other biomolecules.