Nanomaterials-based Sensors for Peroxynitrite Detection and Quantification

Peroxynitrite (ONOO-, PON) plays a crucial role in several cardiovascular dysfunctions and other diseases triggered by oxidative stress. PON is a strong oxidizing agent produced from the diffusion-controlled reaction between nitric oxide radical and superoxide anion-radical. It is also a member of the reactive oxygen-nitrogen species family, which attacks vital components inside the body and initiates deleterious effects via direct and indirect interactions. PON reacts directly with lipids, DNA, and proteins, whereas indirectly, it acts as an initiator of radical-chain reactions. In this work, we have explored various interfaces of manganese-oxide-decorated graphene/hemin and selenium-containing compound for PON detection and quantification. The combination of manganese oxide nanoparticles with the graphene/hemin matrix has allowed for more hemin molecules to be adsorbed on the final composite matrix. As a result, the adsorbed hemin has enhanced the catalytic activity of the final composite and improved the sensitivity towards PON detection. In the same context, a selenium-containing compound (aniline-selenide) has been synthesized and grafted on the electrode surface using the chemistry of diazonium salt. The aniline-selenide-modified electrode showed an increase of approximately 40 times the catalytic current as the aniline-modified electrode. Throughout this project, the preparation methods of the electroactive nanomaterials were described in detail. Moreover, the characterizations of the prepared-materials have been investigated by various physicochemical methods using scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), ultraviolet/visible measurements (UV/Vis), and X-ray photoelectron spectroscopy (XPS). This study showed the importance of using selenium and manganese interfaces as sensitive platforms for PON detection. It also provides the initial stage to extend the use of these interfaces to ultramicroelectrodes sensors for use at the level of single cells