Electrochemiluminescent molecular logic gates based on MCNTs for the multiplexed analysis of mercury(ii) and silver(i) ions

Abstract

In this paper, logic gates with electrochemiluminescence (ECL) signal as outputs were constructed based on the use of the thymine (T)-rich (S₁) or cytosine (C)-rich (S₂) oligonucleotides for the selective analysis of mercury ions (Hg²⁺) or silver ions (Ag⁺), respectively. Firstly, Ru-silica (Ru(bpy)₃²⁺-doped silica) labeled S₁ and S₂ were absorbed onto multiwalled carbon nanotubes (MCNTs) to form MCNTs/Ru-silica labeled S₁/Ru-silica labeled S₂ complex, which result in the quenching of the ECL of Ru-silica via the energy-transfer and electron-transfer process. Upon the MCNTs/S₁/S₂ interaction and coordination chemistry of Hg²⁺ bridge thymine bases and Ag⁺ specifically bridge cytosine bases, OR, INHIBIT, and NOR logic gates were designed to operate the ECL of Ru-silica nanoparticles. The ECL signal changed according to different input combinations, and the combinatorial logic gates (OR and INHIBIT) provided a beneficial approach for multiplex analysis. The proposed logic gates may have a great potential in further DNA circuits and advanced sensors for the identification of multiple targets in complex chemical environments.