Peroxynitrite Sensing Using Electrode Interfaces Decorated with Grafted Diaryl Selenides

Abstract

Peroxynitrite is a highly reactive species that is known to cause damage to cells, and it is challenging to measure its concentration accurately. Electrochemical methods for detecting peroxynitrite are limited, and there is ongoing research to develop effective electrochemical probes or catalytic materials that can serve as interfaces for efficient detection of peroxynitrite. In our previous work we developed and characterized a thin film material based on 4,4’ diaminodiphenyl selenide grafted onto glassy carbon electrodes to create a functional interface for peroxynitrite detection. This selenide-based peroxynitrite sensors demonstrated remarkable sensitivity and a low limit of detection, and we postulated an electrocatalytic catalytic mechanism whereby the grafted selenide moieties act as electroactive mediators that ultimately lead to the catalytic oxidation of peroxynitrite. The positive charge developed on the selenium atom of the diarylselenide upon electrochemical oxidation is crucial for a such electrocatalytic mechanism. To test the validity of the postulated mechanism, we designed other other diarylselenides with different functional groups in the para position of the selenium atom. In this study, we decorated electrodes with diarylselenide moieties bearing various functional groups in the para position of the selenium atom of the diaryl selenide (See Scheme1; R=-H, -OMe, -CF3).We show that the electron-withdrawing -CF3 group significantly improves the sensitivity of the corresponding electrode towards PON. The opposite is observed with the methoxy group, which almost abolishes the mediated electrocatalytic oxidation of PON. We will present the results and analyze these findings in light of the electron-donating or withdrawing ability of the substituents placed in the para position from the selenium atom in the context of the postulated electrocatalytic mechanism mediated by the selenide moiety.