Versatile electrochemiluminescence sensor for dual-potential “off” and “on” detection of double targets based on a novel terbium organic gel and multifunctional DNA network probes

Abstract

In this work, a multifunctional signal probe with DNA network-loaded Ru(phen)32+ and Ag nanocluster (NCs) was assembled, and combined with a novel terbium organic gel to design a versatile electrochemiluminescence (ECL) biosensor for dual-potential “on” “off” assays of Cd2+ and Mg2+. Firstly, target Cd2+-driven DNA walker-amplification process produced a large amount of output DNA, which was used to link the multifunctional DNA network (DNA Net) structure probes with both Ru(phen)32+ and C-rich base to the terbium organic gel (TOG)-modified electrode. Thus the positive potential ECL signal of Ru(phen)32+ was generated, and the negative-potential ECL signal of TOG was quenched by Ag NCs via resonance energy transfer and co-reactant-competition simultaneously, achieving dual signal “on” and “off” assay of Cd2+. Furthermore, the present Mg2+ (second-target) specifically sheared the substrate of DNA enzyme on the electrode, releasing the DNA Net probes with Ru(phen)32+ and Ag NCs to realize “off” and “on” detection of Mg2+ by dual-potential signals. This strategy developed a new versatile biosensor by using dual-potential ECL probes and novel DNA network structure, and opened up a new way for multi-target detection by dual “on” “off” signals, which shows great potential in practical detection. The multifunctional sensing platform was also applied to Cd2+ assay in rice.