Construction of a dual-signal sensing platform based on DNA enhanced peroxidase-activity of iron cobalt oxide nanosheets for thrombin detection

Thrombin played important roles for the diagnosis of neurodegenerative and cardiovascular diseases. Herein, we successfully constructed a rapid and sensitive fluorescence and colorimetric dual-signal sensing strategy for the detection of thrombin by taking advantage of the DNA-enhanced peroxidase like activity FeCo-ONSs and magnetic separation. In this work, single-stranded DNA S1 with thrombin aptamer was used to enhance the catalytic activity of FeCo-ONSs, and single-stranded DNA S2 with different thrombin aptamer was modified on the surface of magnetic beads (MBs) to construct MBs-S2 for subsequent magnetic separation. In the presence of thrombin, S1 and MBs-S2 quickly combined with thrombin and the amount of S1 decreased in the solution after magnetic separation. The enhancement of peroxidase like activity of S1/FeCo-ONSs was weakened, resulting in the inhibition of the catalytic oxidation process of substrate TMB. The formation of oxTMB and the fluorescence quenching efficiency of MoS2 QDs were further affected. Therefore, the quantitative detection of thrombin can be achieved by measuring the absorption signal of oxTMB and the fluorescence signal of MoS2 QDs. The limits of detection for thrombin were 0.67 pM and 2.36 pM by the outputting fluorometric and colorimetric dual signals, respectively. This sensing strategy not only has high specificity, but also can be expanded as a more universal platform for sensitive detection of different proteins by changing the aptamer probe pairs.