Exogenous coreactant-free integrated ECL biosensor based on P5AIn/Fe(II)-MOF for sensitive trimethylamine N-oxide detection.

BACKGROUND: Trimethylamine N-oxide (TMAO) has attracted significant attention as a critical marker for seafood freshness. However, the development of integrated methods combining rapid sample pretreatment with highly sensitive detection for TMAO remains a significant gap. A novel exogenous coreactant-free integrated ECL immunosensor was constructed for sensitive TMAO detection using poly(5-aminoindole)/Iron-based metal-organic framework (P5AIn/Fe-MOF) as a dual-functional platform.

RESULTS: In the P5AIn/Fe-MOF composite, the Fe-MOF served as both a co-reaction promoter and an in-situ reduction matrix, exhibiting unique synergistic effects with P5AIn. P5AIn not only enhanced the structural stability of Fe-MOF but also significantly improved electron transfer efficiency. Meanwhile, the inherent conductivity and porous structure of Fe-MOF facilitated rapid electron transfer during the conversion of TMAO to trimethylamine (TMA), maximizing catalytic accessibility. The generated TMA serves as an endogenous 'coreactant' to amplify ECL signals, thereby achieving exogenous coreactant-free effects and simplifying operational procedures. An efficient ECL probe was designed by loading Ru(bpy)32+ onto Zn3(HHTP)2 and conjugating it with antibodies. The confined pore structure of Zn3(HHTP)2 effectively suppressed energy dissipation, significantly boosting the ECL response of Ru(bpy)32+. The constructed biosensor has a wide linear range of 0.1-100 ng/mL and a low detection limit of 0.033 ng/mL. Its successful application in frozen shrimp samples validated its practical detection capability.

SIGNIFICANCE: This study proposes a novel exogenous coreactant-free detection strategy, integrating sample pretreatment and signal generation into a single platform. It offers a new approach for simple, rapid and sensitive TMAO detection, holding promising application prospects in marine food safety monitoring.