DNA nanotetrahedron linked dual-aptamer based voltammetric aptasensor for cardiac troponin I using a magnetic metal-organic framework as a label

An ultrasensitive voltammetric aptasensor was constructed to analyze cardiac troponin I (cTnI). It is based on DNA nanotetrahedron (NTH) linked dual-aptamer (dAPT) and magnetic metal organic frameworks (mMOFs) of type Fe3O4@UiO-66. Firstly, the DNA NTH linked dAPT (Tro4 and Tro6) were immobilized on a gold electrode for improving the capture efficiency of cTnI. The novel mMOFs Fe3O4@UiO-66 was then decorated by Au@Pt nanoparticles (Au@PtNPs), horseradish peroxidase (HRP), G-quadruplex/hemin (GQH) DNAzyme, and two types of aptamers to form signaling nanoprobes. In the presence of cTnI, an aptamer-protein-nanoprobe sandwich-type structure is formed. Afterward, the nanoprobes including enzyme, GQH DNAzyme and Fe3O4@UiO-66/Au@PtNP were utilized to catalyze the oxidation of hydroquinone by hydrogen peroxide for the electrochemical signals amplification, typically at a working potential of -0.1V (vs. Ag/AgCl). The voltammetric signal increases linearly in the 0.01 to 100ngmL(-1) cTnI concentration range, and the detection limit is 5.7pgmL(-1).