Hemin as a Molecular Probe for Nitric Oxide Detection in Physiological Solutions: Experimental and Theoretical Assessment.

Given its pivotal role in modulating various pathological processes, precise measurement of nitric oxide ( ● NO) levels in physiological solutions is imperative. The key techniques include the ozone-based chemiluminescence (CL) reactions, amperometric ● NO sensing, and Griess assay, each with its advantages and drawbacks. In this study, a hemin/H 2 O 2 /luminol CL reaction was employed for accurately detecting ● NO in diverse solutions. We investigated how the luminescence kinetics was influenced by ● NO from two donors, nitrite and peroxynitrite, while also assessing the impact of culture medium components and reactive species quenchers. Furthermore, we experimentally and theoretically explored the mechanism of hemin oxidation responsible for the initiation of light generation. Although both hemin and ● NO enhanced the H 2 O 2 /luminol-based luminescence reactions with distinct kinetics, hemin's interference with ● NO/peroxynitrite - modulated their individual effects. Leveraging the propagated signal due to hemin, the ● NO levels in solution were estimated, observing parallel changes to those detected via amperometric detection in response to varying concentrations of the ● NO-donor. The examined reactions aid in comprehending the mechanism of ● NO/hemin/H 2 O 2 /luminol interactions and how these can be used for detecting ● NO in solution with minimal sample size demands. Moreover, the selectivity across different solutions can be improved by incorporating certain quenchers for reactive species into the reaction.