Studying the reaction of peroxynitrite with myoglobin in meat extract samples using cobalt phthalocyanine-modified screen printed carbon electrodes and a flow injection analysis system

Reactive oxygen/nitrogen species (ROS/RNS) have a great impact on cellular response to stress, cell proliferation, cell death, cancer, aging, or male infertility. Additionally, in the food industry and for consumers as well, it is very important to monitor quality and freshness of raw meat. Different factors are a sign of meat alteration (e.g., discoloration, rancidity, alteration of flavor). One pathway of alteration is the scavenging activity of myoglobin towards RNS (such as peroxynitrite, PON). This paper presents the development of an electrochemical PON sensor using cobalt phthalocyanine (CoPc) as a simple, cost effective, highly thermally stable, biomimetic catalyst, and the application of this electrochemical screen-printed carbon electrode (SPCE)-based sensor to meat extract samples, using flow injection analysis (FIA). The reduction of peroxynitrite, mediated by CoPc, occurs at a very low potential (around 0.1 V vs. Ag/AgCl pseudoreference); as for higher potentials, the mechanism of mediation changes, and the electro-oxidation of PON is observed. The surface of the modified electrode was characterized using SEM, FTIR and Cyclic Voltametry. The interaction of PON with myoglobin was studied using both UV-Vis and chronoamperometry (at 0.1 V, using the FIA system). The calibration of the electrode was performed: Ired (nA) = 6.313·CPON (µM) + 17.469; (R² = 0.9938). The calculated LOD was equal to 2.37 µM and the linear range was 3–180 µM. The performance of the electrode can be further improved using a pre-treatment (electro-reduction of the CoPc deposited film, at −0.3 V, during 60s). This could help us monitor and quantify how much PON was decomposed and when meat extracts are spiked with different PON concentrations, in a highly selective, sensitive, and reproducible way.