A study on the influence of environmental toxicants on the luminol/KSCN/H₂O₂/Cu oscillator

Oscillatory reactions involving periodical oxido-reduction reactions are commonly found in lifeforms. The purpose of this study consisted in using the luminol-KSCN-H2O2-Cu(II) oscillator to probe the capacity of known environmental xenobiotics to alter these oscillatory reactions. The above oscillator was studied in the presence of increasing concentrations of ascorbate (a reducer), cerium (Ce IV; an oxidant), samarium oxide (SmO), nanocerium (nCeO2), zinc oxide nanoparticles (nZn), polyethylene nanoplastics (PE), cadmium tellurium quantum dots (CdTe) and copper-zinc-iron composite (nCuZnFeO) to monitor changes in the cyclic luminescent profiles. In normal conditions, 4 amplitude changes were generated during the first 15 min with luminescence spikes occurring at each 2.5-3 min. Following Fourier transformation, the amplitudes of the major oscillations were obtained for the first 9 frequencies and showed negative slope β between amplitudes and frequencies, which is related to the fractal dimension fD. The addition of the above compounds in the reaction media produced characteristic changes in oscillations with the appearance of amplitudes at higher frequencies at various intensity thereby decreasing the slope β and increasing the fD. The data also revealed that the fD followed the reported toxicity values of these compounds in fish suggesting that electron flow occurring in increased fD is associated to toxicity. Although more research is needed, the use of chemical oscillators based on oxido-reduction reactions could serve as a proxy to identify potential toxicity of xenobiotics.