Electrochemiluminescence-colorimetric dual-mode biosensor based on CeO₂:Eu³⁺ nanozyme amplification for the detection...

Conventional glucose (Glu) sensing platforms predominantly rely on single-signal readouts, a strategy inherently vulnerable to matrix interference and this limitation often leads to inaccurate quantification when analyzing complex biological or environmental samples. To address this challenge, we herein developed an electrochemiluminescence (ECL)-colorimetric dual-mode detection strategy for Glu, based on CeO₂:Eu³⁺ nanomaterials, with the aim of enhancing the accuracy of Glu quantification. The CeO₂:Eu³⁺ nanomaterials exhibited excellent ECL performance in an ECL system using potassium persulfate (K₂S₂O₈) as the coreactant. Notably, their ECL intensity could be effectively quenched by hydrogen peroxide (H₂O₂), and the quenching efficiency showed a linear correlation with H₂O₂ concentration, this relationship enabled the quantitative detection of H₂O₂. Furthermore, the peroxidase-mimetic activity of CeO₂:Eu³⁺ nanomaterials further enhanced the ECL quenching efficiency, thereby improving the sensitivity of H₂O₂ detection. Concurrently, the CeO₂:Eu³⁺ nanomaterials displayed remarkable peroxidase-mimetic activity in the chromogenic reaction between 3,3',5,5'-tetramethylbenzidine (TMB) and H₂O₂, inducing a distinct color transition from colorless to blue that could be easily visualized and recorded using a smartphone. Leveraging these properties of CeO₂:Eu³⁺ nanomaterials, combined with the reaction mechanism wherein Glu generates H₂O₂ under the catalysis of Glu oxidase (GOx), we established a dual-mode detection method for Glu. Under optimized experimental conditions, this method achieved highly sensitive and selective Glu detection: the limit of detection (LOD) was as low as 0.033 nM for the ECL mode and 1.46 μM for the colorimetric mode (S/N = 3). This work integrates the unique dual functionalities of CeO₂:Eu³⁺ nanomaterials to realize sensitive dual-mode Glu detection, providing new insights for the innovative design of dual-mode sensors and exhibiting significant potential in clinical diabetes monitoring.