Nitrogen-doped carbon dot and DNA tetrahedron nanostructure based electrochemiluminescence aptasensor for AFB1 detection

An electrochemiluminescence (ECL) aptasensor with aptamer as recognition element, N-doped carbon dots (N-CDs) as luminophore, and DNA tetrahedral nanostructure (DTN) as carrier to loading abundant N-CDs for signal amplification was developed for ultra-sensitive aflatoxin B 1 (AFB 1 ) detection. The complementary DNA (cDNA) was firstly immobilized on the Au electrode (AuE) surface to hybridize with the AFB 1 aptamer. In the presence of AFB 1 , it would competitively with cDNA for binding the aptamer, causing the exposure of cDNA. DTN modified with AFB 1 aptamer on top and N-CDs on the four vertices would combine with cDNA onto the AuE surface to generate ECL signals due to electron transfer between co-reactants (K 2 S 2 O 8 ) and N-CDs, which was positively related to the concentration of AFB 1 . Due to the high specificity of aptamer, the outstanding ECL performance of N-CDs and the enhanced signal output of DTN/N-CDs probes, the as-constructed ECL aptasensor realized excellent sensitivity with a low detection limit of 77 pg/mL and a wide linear concentration of 1.0 × 10 −1 -1.0 × 10 4 ng/mL for AFB 1 , as well as fascinating accuracy with acceptable recoveries of 89.54–111.0% in the spiked Coix seed matrices. Successful application for AFB 1 detection in actual samples confirmed the extensive practicability of the ECL aptasensor, providing a universal platform for more trace contaminants by altering the corresponding aptamers.