Nitrogen-doped graphene quantum dots doped silica nanoparticles as enhancers for electrochemiluminescence thrombin aptasensors based on 3D graphene

A sensitive electrochemiluminescence (ECL) aptasensor based on 3D graphene is described for thrombin detection utilizing nitrogen-doped graphene quantum dots doped silica (NGQDs@SiO2) nanocomposite labeling as an enhancer. Ru(bpy)32+-Pt nanoparticles (Ru-PtNPs) with an ECL signal were dropped onto a 3D graphene-modified electrode, and then, a complementary thrombin aptamer (cDNA) was conjugated to the Ru-PtNPs. Finally, NGQDs@SiO2, coupled with the thrombin aptamer as the booster, was attached to the electrode surface by using hybridization with the cDNA, and the ECL intensity was efficiently enhanced. The target thrombin induced the NGQDs@SiO2 nanocomposites labeled with the thrombin (TB) aptamer to be extracted because of their strong binding with thrombin. The immobilization amount of NGQDs@SiO2 on the modified electrode decreased. Thus, the presence of thrombin could result in a decrease in the ECL signal. On the basis of the signal amplification factors, the fabricated ECL aptasensor demonstrated excellent properties with concentrations varying from 2.0 pM to 50 nM and a detection limit of 23.1 fM.