An electrochemiluminescence sensor for ultrasensitive detection of Hg2+ based on self-enhanced Ru-QDs@SiO2 luminophore and P6ICA/MoS2 as co-reaction accelerator

An electrochemiluminescence (ECL) biosensor combined with DNA signal amplification technology was constructed for Hg2+ detection based on an efficient self-enhanced ECL luminophore (Ru-QDs@SiO2) and a novel co-reaction accelerator poly(indole-6-carboxylic acid)/molybdenum disulfide (P6ICA/MoS2). The Ru-QDs@SiO2 nanosphere was prepared by co-encapsulating the donor CdS QDs and acceptor Ru(bpy)32+ into a silica nanoparticle, which enabled ECL resonance energy transfer (ECL-RET) to occur inside the Ru-QDs@SiO2 nanospheres, thereby shortening the electron transfer path between donor and acceptor, further enhancing the ECL signal intensity. Additionally, P6ICA/MoS2 was used as a novel co-reaction accelerator for the detection of Hg2+. P6ICA/MoS2 exhibits excellent conductivity and a well-defined hierarchical structure, making it to effectively facilitate the generation of more co-reactive free radicals, and provide a good substrate for fixing abundant cDNA. Meanwhile, introducing the Exo III-assisted target recycling strategy further amplifies the ECL signal, simplifying the construction process. The as-fabricated ECL biosensor exhibits an ultrasensitive detection ability of Hg2+ with a broad liner detection range from 100 nM ∼ 0.1 fM, and the detection limit can be down to 0.07 fM. Moreover, this ECL biosensor shows excellent stability, reproducibility and selectivity, and is successfully utilized for the detection of Hg2+ in seawater with good performance.