Electrochemiluminescence Sensor Based on CeO₂ Nanocrystalline for Hg²⁺ Detection in Environmental Samples

The excessive concentration of heavy-metal mercury ions (Hg²⁺) in the environment seriously affects the ecological environment and even threatens human health. Therefore, it is necessary to develop rapid and low-cost determination methods to achieve trace detection of Hg²⁺. In this paper, an Electrochemiluminescence (ECL) sensing platform using a functionalized rare-earth material (cerium oxide, CeO₂) as the luminescent unit and an aptamer as a capture unit was designed and constructed. Using the specific asymmetric matching between Hg²⁺ and thymine (T) base pairs in the deoxyribonucleic acid (DNA) single strand, the "T-Hg-T" structure was formed to change the ECL signal, leading to a direct and sensitive response to Hg²⁺. The results show a good linear relationship between the concentration and the response signal within the range of 10 pM-100 µM for Hg²⁺, with a detection limit as low as 0.35 pM. In addition, the ECL probe exhibits a stable ECL performance and excellent specificity for identifying target Hg²⁺. It was then successfully used for spiked recovery tests of actual samples in the environment. The analytical method solves the problem of poor Hg²⁺ recognition specificity, provides a new idea for the efficient and low-cost detection of heavy-metal pollutant Hg²⁺ in the environment, and broadens the prospects for the development and application of rare-earth materials.