Ru(bpy)32+-doped silica nanoparticle aptasensor for detection of thrombin based on electrogenerated chemiluminescence

A new electrogenerated chemiluminescent (ECL) detection system for protein using the aptamers was developed. Two different aptamers, which recognize different positions of thrombin, were chosen to construct sandwich type sensing system for protein, one was immobilized onto the gold electrode for capturing thrombin onto the electrode and the other was used for detection. To obtain the signal, the aptamer for detection was labeled with tris(2,2'-bipyridyl)ruthenium(II)-doped silica nanoparticles (Ru(bpy)(3)(2+) -doped SNPs). The increase of the ECL sig nal generated by Ru(bpy)(3)(2+) -doped SNPs was observed in dependent manner on the concentration of thrombin added. Bovine serum albumin and bovine hemoglobin had almost negligible responses. The assay allows detection at levels as low as 1.0 fmol center dot L-1 of the thrombin due to that there are a large number of Ru(bpy)(3)(2+) molecules inside SNPs labeled on the aptamer used for detection. The ECL signal was linearly related to the concentration of the thrombin analyte in the range of 2.0 fmol center dot L-1 to 2.0 pmol center dot L-1.