Hydrogels for electrochemiluminescence sensing: interfacial mechanisms and multifunctional roles

Electrochemiluminescence (ECL) sensing technology has emerged as a powerful analytical tool owing to its high sensitivity, exceptional signal-to-noise ratio, and excellent spatiotemporal controllability. Nevertheless, practical applications of ECL sensors in complex matrices remain constrained by several persistent challenges, including severe interfacial biofouling, aggregation-caused quenching of luminophores, and insufficient molecular recognition selectivity. As versatile three-dimensional porous materials, functional hydrogels have evolved from passive electrode supporting substrates into multifunctional active interfaces for advanced ECL sensing. This review systematically elaborates the progress and multifaceted regulatory mechanisms of hydrogel-based ECL systems. Three core functionalities of hydrogels are highlighted, namely size-exclusion antifouling capability, spatial confinement that enables aqueous-compatible aggregation-induced ECL, and molecularly imprinted network architectures for active signal gating and selectivity improvement. The structural and physicochemical principles underlying these strategies are discussed, with particular attention to the interplay between hydrogel network properties and ECL transduction behavior. Furthermore, current technical challenges in multifunctional integration and interfacial synergy are discussed, and future directions are proposed. This hydrogel interfacial engineering strategy offers a promising route to advance the practical analytical capacity of ECL sensing.