Monitoring disease-implicated hydrogen sulfide in blood using a facile deproteinization-based electrochemiluminescence chemosensor system

Hydrogen sulfide (H2S), an antioxidant and cell signaling molecule, plays a critical role in redox reactions in the biological system, and its imbalances in blood levels have been implicated in various diseases. Here, we demonstrate a novel chemosensor-based "turn-on" electrochemiluminescence (ECL) system for the selective and sensitive detection of H2S in a type 1 diabetes rat model. Our luminogenic chemosensor (Probe) is a redox-stable cyclometalating iridium (III) complex with emission-quenching 2,4-dinitrophenyl ether (DNP) that shows a significant enhancement in emission intensity upon cleavage of DNP by selective reaction towards H2S. To achieve robust and reliable ECL emission of Probe for biological analysis, we developed a facile deproteinization protocol based on organic solvent-induced protein precipitation/syringe filtration that eliminates uncontrolled protein adsorption on the electrode surface from protein-rich biological samples. Our deproteinization-assisted ECL chemosensor system showed effectiveness in detecting disease-associated H2S levels in biological media with a linear response in the range of 0–250 µM (R2: 0.992). It enables reliable in vitro monitoring of H2S level changes in blood samples of a type 1 diabetes rat model (P = 0.0296). This strategy to integrate chemosensor-based ECL and facile deproteinization protocol provides a sensitive and rapid disease-monitoring platform for detecting small-molecule biomarkers.