Charge-regulated reduction potential of phenazine enabling electrochemiluminescence for monitoring riboflavin in beans germination

Abstract

Nowadays, organic molecules with excellent fluorescence often lack electrochemiluminescence (ECL), which restricts their analytical and biomedical applications. In this work, we functionalized phenazine (PZ) derivatives with the charged moieties and activated their ECL properties using K₂S₂O₈ as a coreactant, achieving a significant “off-to-on” ECL emission transition. For that, 7,8-dihydroxyphenazine-2-carboxylic acid (DHPZ) was synthetized, showing the largest ECL efficiency of 56.4 % (versus Ru(bpy)₃²⁺ as a standard). Its subsequent self-assembly with ethylene glycol (termed DHPZ-EG) as emitter further boosted the 4.0-fold ECL efficiency. In the presence of riboflavin (RF), the DHPZ-EG assemblies underwent light-induced photocatalytic oxidation (PR), enabling efficient ECL signal transduction via the structure-property correlation. The as-established ECL sensor exhibited a wide linear section from 10 nM to 1.0 mM, a limit of detection (LOD, 1.5 nM), and the ability to monitor broad bean growth metabolism. This work opens a novel avenue for designing organic luminophores and developing sensors for dynamic botanical tracking.