Sensitive and selective detection of Hg²⁺ in tap and canal water via self-enhanced ECL aptasensor based on...

In the present study, a novel self-enhanced electrochemiluminescence (ECL) aptasensor which combined self-enhanced ECL composite as signal response element and aptamer as the specific recognition element was firstly proposed for the sensitive and selective detection of Hg²⁺. Innovatively, the luminophore Ru(bpy)₃²⁺-doped silica nanoparticles functionalized with 3-aminopropyltriethoxysilane (NH₂-Ru@SiO₂) and the co-reactant nitrogen doped graphene quantum dots (NGQDs) were bound together to form the self-enhanced ECL composite, NH₂-Ru@SiO₂-NGQDs, by electrostatic adsorption. Satisfactorily, high and stable luminous efficiency of NH₂-Ru@SiO₂-NGQDs was obtained benefited from the short electron transfer distance and low energy loss of self-enhanced-typal ECL composite. For the fabrication of the self-enhanced ECL aptasensor for Hg²⁺ detection, the Hg²⁺ aptamer, of which one end was connected to NH₂-Ru@SiO₂-NGQDs, and the other end was fixed on glass carbon electrode (GCE) surface through Au-S bond, was served as a bridge. Upon the addition of Hg²⁺, the aptamer was bent due to the formation of thymine-Hg²⁺-thymine (T-Hg²⁺-T) specific structure, which caused the self-enhanced ECL composite was close to the GCE surface. On this basis, a linearly enhanced ECL signal was acquired with the concentration of Hg²⁺ in the range of 5.0 × 10^-11 M - 1.0 × 10^-6 M with excellent selectivity, repeatability and stability in 3 min for each assay. In addition, the proposed aptasensor showed satisfying accuracy and practicability for Hg²⁺ analysis in tap and canal water verified by the inductively coupled plasma-mass spectrometry (ICP-MS) method.