H2O2-assisted photoelectrocatalytic degradation of Mitoxantrone using CuO nanostructured films: Identification of by-products and toxicity.

CuO nanostructured thin films supported on silicon with 6.5 cm2 area (geometric area greater than the studies reported in the literature) were synthesized by a chemical bath deposition technique. The electrodes were characterized by MEV, XRD, XPS, contact angle, cyclic voltammetry and electrochemical impedance spectroscopy analyses. To evaluate the photoelectrochemical properties of the CuO films, photocurrent-voltage measurements were performed using linear voltammetry. The catalytic activities of CuO nanostructures were evaluated by monitoring photodegradation of Mitoxantrone (MTX) under UV-A light irradiation. The method of photoelectrocatalysis (PEC), applying a voltage of 1.5 V and assisted by adding H2O2, was undertaken. To the best of our knowledge, no studies on the degradation of anticancer agents using PEC process have been found in the literature. For comparison purposes, experiments were performed under the same conditions by assisted photocatalysis (PC) with H2O2 and direct photolysis. CuO deposits consist of a needle-like morphology. The presence of CuO in the tenorite phase was evidenced by XRD and the XPS spectra showed the presence of copper(II) oxide. The increase in current under illumination shows that CuO exhibits photoactivity. The PEC system showed a 75% level of MTX degradation, while the level achieved using PC was 50%. Under UV-A light alone only 3% removal was obtained after 180 min. Up to 10 by-products were identified by chromatography-mass spectrometry (LC-MS) with m/z values ranging between 521 and 285 and a plausible degradation route has been proposed. It is worth mentioning that 9 by-products identified in this work, were not found in the literature in other studies of degradation or products generated as metabolites. The toxicity tests of MTX before and after PEC treatment with Artemia Salina and Allium cepa showed a decrease in the acute toxicity of the medium as the antineoplastic was degraded.

A cooperative transition from the semi-flexible to the flexible regime of polymer elasticity: Mitoxantrone-induced DNA condensation.

We report a high cooperative transition from the semi-flexible to the flexible regime of polymer elasticity during the interaction of the DNA molecule with the chemotherapeutic drug Mitoxantrone (MTX). By using single molecule force spectroscopy, we show that the force-extension curves of the DNA-MTX complexes deviate from the typical worm-like chain behavior as the MTX concentration in the sample increases, becoming straight lines for sufficiently high drug concentrations. The behavior of the radius of gyration of the complexes as a function of the bound MTX concentration was used to quantitatively investigate the cooperativity of the condensation process. The present methodology can be promptly applied to other ligands that condense the DNA molecule upon binding, opening new possibilities in the investigation of this type of process and, more generally, in the investigation of phase transitions in polymer physics.

Application of Fenton, photo-Fenton, solar photo-Fenton, and UV/H2O2 to degradation of the antineoplastic agent mitoxantrone and toxicological evaluation.

In the present study, selected advanced oxidation processes (AOPs)-namely, photo-Fenton (with Fe(2+), Fe(3+), and potassium ferrioxalate-FeOx-as iron sources), solar photo-Fenton, Fenton, and UV/H2O2-were investigated for degradation of the antineoplastic drug mitoxantrone (MTX), frequently used to treat metastatic breast cancer, skin cancer, and acute leukemia. The results showed that photo-Fenton processes employing Fe(III) and FeOx and the UV/H2O2 process were most efficient for mineralizing MTX, with 77, 82, and 90% of total organic carbon removal, respectively. MTX probably forms a complex with Fe(III), as demonstrated by voltammetric and spectrophotometric measurements. Spectrophotometric titrations suggested that the complex has a 2:1 Fe(3+):MTX stoichiometric ratio and a complexation constant (K) of 1.47 × 10(4) M(-1), indicating high MTX affinity for Fe(3+). Complexation partially inhibits the involvement of iron ions and hence the degradation of MTX during photo-Fenton. The UV/H2O2 process is usually slower than the photo-Fenton process, but, in this study, the UV/H2O2 process proved to be more efficient due to complexing of MTX with Fe(III). The drug exhibited no cytotoxicity against NIH/3T3 mouse embryonic fibroblast cells when oxidized by UV/H2O2 or by UV/H2O2/FeOx at the concentrations tested.