Influence of TDN on conventional aptasensors

A novel electrochemiluminescence (ECL) aptasensor based on tetrahedral DNA nanostructures (TDN) and CdTe QDs was fabricated for the detection of acetamiprid residues. Three TDNs with different sizes were successfully designed and synthesized. The unique and rigid tetrahedral structure of TDN can ensure that the biological probe always maintains the orientation perpendicular to the sensing interface, greatly reducing the background noise and effectively improving the signal-to-noise ratio. It has great significance to improve the order of the probe on the sensing interface. The ECL signals of TDN with different sizes were compared with the conventional aptasensors (c-DNA) modified by single-stranded DNA (ssDNA). The results displayed that TDN can effectively amplify the sensor's ECL signal, the size of TDN was negatively correlated with the amplification coefficient and hybridization time of aptamer. Compared various parameters of the c-DNA sensor and TDN13 sensor which with the highest signal. The linear range of the TDN13 sensor is 0.100 pM∼100 nM, the detection limit is 34.0 fM. The linear range of the c-DNA sensor is 1.00 pM∼10.0 nM, the detection limit is 178 fM. TDN13 sensor was applied to measure acetamiprid residues in Chinese cabbage samples with satisfactory results.