Electrochemiluminescence sensor based on the target recognition-induced aggregation of sensing units for Hg2+ determination

•A surface-tethered ECL sensor based on the target-induced aggregation of sensing units was developed for Hg2+ analysis.•Thymine (T) assembled UCNP (T-UCNP) was used as sensing unit to specifically absorb Hg2+ by T-Hg2+-T matching.•The presence of Hg2+ can trigger the generation of UCNP-T-Hg2+-T-UCNP reticular architecture on solid electrode surface.•Target recognition and the signal accumulation were realized simultaneously by the target-induced aggregation of T-UCNP.•Hg2+ quantification was conducted by detecting the ECL signal amplified by the captured UCNP. In this work, the target recognition-induced aggregation of sensing units was initiated on a solid electrode to develop an enhanced surface-tethered electrochemiluminescence (ECL) sensor for Hg2+ analysis. Thymine (T) was assembled on upconversion nanoparticles (UCNP) as sensing units (T-UCNP). In the presence of Hg2+, the T monolayer-modified Au electrode (AuE/T) absorbed Hg2+ and T-UCNP by T-Hg2+-T matching. Surface-tethered T-UCNP further recruited more Hg2+, as well as T-UCNP, thus forming a UCNP-T-Hg2+-T-UCNP reticular architecture on the surface of the electrode. Hg2+ quantification was subsequently conducted by detecting the ECL signal amplified by the captured UCNP. During ECL analysis, target recognition and signal accumulation were simultaneously realized by the target-induced aggregation of T-UCNP. The simple and flexible strategy proposed in this work immobilized ECL emitters efficiently and simplified the preparation procedure of the sensor. The proposed ECL sensor displayed a low limit of detection (LOD) of 0.4 pmol L−1 and favorable recoveries (84.8 %–98.7 %) during real-sample analysis.