The Ru complex and hollow gold nanoparticles branched-hydrogel as signal probe for construction of electrochemiluminescent aptasensor

In this work, a novel Ru complex and hollow gold nanoparticles branched-poly(N-(3-aminopropyl)methacrylamide) hydrogel composites (pNAMA-Ru-HGNPs) were prepared and used as electrogenerated chemiluminescence (ECL) signal probe to construct aptasensor for ultrasensitive detection of thrombin (TB). Herein, [Ru(phen)2(cpaphen)]2+ linked N-(3-aminopropyl)methacrylamide and hollow gold nanoparticles functionalized N-(3-aminopropyl)methacrylamide were used as two polymer monomers to prepare pNAMA-Ru-HGNPs composites via free-radical polymerization. The obtained hydrogel composite, containing amount of Ru complex and HGNPs, were used as effective tag-carriers for the immobilization of thrombin binding aptamer II (TBA II) to form the pNAMA-Ru-HGNPs labeled TBA II (pNAMA-Ru-HGNPs-TBA II). For building the interface of the aptasensor, dendritic gold nanoparticles reduced by poly(ethyleneimine) (PEI@DGNPs) were modified on the carbon nanotube-nafion (CNTs-Nf) coated electrode through electrostatic adsorption, which was used not only as matrix for immobilization of thrombin binding aptamer I (TBA I) but also as enhancer to amplify the ECL signal because PEI is an efficient co-reactant of Ru complex. Target TB was sandwiched between pNAMA-Ru-HGNPs-TBA II and TBA I, resulting in the ECL signals relevant to the TB concentrations. Combining the novel pNAMA-Ru-HGNPs containing amount of Ru complex as the ECL signal probe and PEI@DGNPs as the enhancer for signal amplification, the sandwich ECL aptasensor was constructed for the detection of TB with a wide range of 1.0 fM to 10 pM and a low detection of 0.54 fM.