Redox-encoded molecular recognition enables enzyme-free potentiometric sensing of electroinactive glutamate.

Abstract

Glutamate (Glu), the major excitatory neurotransmitter in the central nervous system, is intrinsically electroinactive, making its direct electrochemical detection challenging and often requiring enzyme-mediated signal transduction. Here, we introduce a redox-encoded molecular recognition strategy that converts selective binding of electroinactive Glu into a potentiometric signal without enzymatic catalysis. The resulting glutamate potentiometric redox-encoded sensor (Glu-PRES) integrates a molecularly imprinted polydopamine (PDA) recognition layer with a Prussian Blue (PB) redox transducer on a bipolar carbon fiber electrode. Selective Glu binding within the imprinted cavities modulates the local interfacial environment and ionic accessibility of the underlying PB layer, inducing a PB-associated potential shift that is measured against a stable IrCl63-/IrCl62- redox interface through galvanic potentiometry. Glu-PRES provides a broad linear range of 0.10-400 μM with a detection limit of 31 nM, while responses to physiologically relevant interferents remain below 14% of that to 10 μM Glu. The sensor also exhibits reversible potential responses upon repeated switching between 100 nM and 1 μM Glu, together with strong resistance to protein fouling. The sensor further resolves graded Glu-release dynamics in a brain hematoma-mimicking hydrogel model. These results demonstrate a recognition-to-redox potential encoding strategy for enzyme-free potentiometric sensing of electroinactive molecular targets.

Abstract as supplied by the indexing source. © the authors / publisher.