LAUSR

As various aptasensors are adopted in clinical diagnosis, the development of convenient multiple-target determination is a field of ever-increasing interests. Herein, a label-free and amplified electrochemiluminescence (ECL) sensing platform was constructed to detect multiple targets of hemin, glucose and thrombin (TB) using peroxydisulfate (S2O82-) solution, which was one of the most convenient and economical ECL systems. It was worth mentioning that the target-induced bi-enzyme cascade catalysis reaction was developed to increase the ECL response strongly of S2O82- solution due to the production of (1O2)2* from the inter-reaction between reactive oxygen species (ROS) and sulfate radical (SO4•-). Specifically, with the layer-by-layer assembly of multi-walled carbon nanotubes (MWCNTs), glucose oxidase (GOx) and gold nanoparticles (AuNPs) as the interface, the guanine-rich (G-rich) thrombin aptamer (TBA) was anchored for hemin (target 1) detection, due to the electrocatalysis of hemin/G-quadruplex as a horseradish peroxidase mimicking DNAzyme (HRP-DNAzyme) towards dissolved oxygen for ROS generation. Second, in the presence of glucose (target 2), the ECL intensity was improved because glucose was the substrate of the bi-enzyme cascade catalysis reaction. Third, when TB (target 3) was sequentially incubated based on the above-mentioned aptasensor, the bi-enzyme catalysis was inhibited to decrease the ECL signal, due to the steric hindrance effect of the TB protein. As a result, the aptasensor achieved the nanomolar detection for hemin (3.33 nM), the micromolar detection for glucose (0.33 μM) and the femtomolar detection for TB (3.33 fM), respectively.