A ratiometric electrochemiluminescence strategy based on two-dimensional nanomaterial-nucleic acid interactions for...

Two-dimensional (2D) nanomaterial-nucleic acid interactions have been widely used in the construction of fluorescent sensors, but they are rarely used in the construction of electrochemiluminescent (ECL) sensors and have never been used in the design of ratiometric ECL sensors. Therefore, a ratiometric ECL sensing platform was developed in this study based on the ECL resonance energy transfer (ECL-RET) of graphitic carbon nitride nanosheets (GCNNs)/Ru(bpy)₃²⁺ donor/acceptor pair. The 2D GCNNs showed much weaker affinity to the long dsDNA duplexes formed by hybridization chain reaction (HCR) than Ru(bpy)₃²⁺-lableled fuel hairpin DNAs (H1 and H2) for HCR. Therefore, the target-initiated HCR resulted in the luminescence enhancement of the GCNNs at 460 nm and the luminescence attenuation of the Ru(bpy)₃²⁺ at 610 nm. By measuring the I_{460 nm}/I_{610 nm} ratios, quantitative analysis of microRNA-133a was realized with a limit of detection of 0.41 pM. In addition, this ECL-RET sensing platform can be easily extended to detect metal ions or aptamer substrates by simply redesigning helper DNAs without changing the sequences of fuel hairpin DNAs. Moreover, due to the programmability of HCR, a series of sensitive logic gates ("OR", "INHIBIT", "AND", "NAND" and "INHIBIT-OR") based on the ECL-RET ratiometry can be constructed and responded to as low as 100 pM of Hg²⁺ or Ag⁺.