Electrochemiluminescent solid-droplet via coordination inhibition in high transparency hydrogel for convenient analysis of heavy metal ions

Despite the significant advantages of electrochemiluminescence (ECL) technology in ultrasensitive analysis of various molecules, the traditional three-electrode ECL system utilizes solution phase as the reaction medium often requires laborious preparations of the solution, leading to a relative complex and potential contamination. In this study, an organic ECL hydrogel based on poly(vinyl alcohol)/sodium alginate/glycerol (PVA/SA/Gly) hydrogel with luminophore tris (2,2′-bipyridine) ruthenium (Ⅱ) hexafluorophosphate ( R u ( b p y ) 3 2 + ) and co-reactant N, N’-bis (salicylidene)-1, 2-propanediamine (PropH) was explored for the construction of a novel solid-phase portable ECL sensing platform to detect heavy metal ions. To be specific, the unique Schiff base cavity structure of PropH specifically coordinated with Co 2+ , altering that its own nitrogen atoms’ electron cloud distributes to hinder co-reaction and reduce the hydrogel’s ECL emission. Notably, this novel ECL system utilized an organic ECL hydrogel as the reaction vessel, streamlining detection procedures and reducing detection time. Furthermore, the organic ECL hydrogel exhibited excellent stability and prolonged storage capability while maintaining strong ECL emission even after extended periods at room temperature. The proposed solid-phase portable ECL sensing platform demonstrates an excellent linear range from 1 nM to 10 mM and low detection limit of 0.31 nM for Co 2+ , providing new strategies for practical application capabilities in the field of food safety detection and environmental monitoring.