Comparative Study of the Oxidative Degradation of Different 4-Aminobenzene Sulfonamides in Aqueous Solution by Sulfite Activation in the Presence of Fe(0), Fe(II), Fe(III) Or Fe(VI)

This study is focused on advanced oxidation technologies (AOTs) using the combined effect of Fe(0–VI)/sulfite systems, that produce mainly SO4•− radicals, to remove different 4-aminobenzene sulfonamides (SAs), namely sulfamethazine, sulfadiazine, sulfamethizole, from aqueous solutions. Results obtained showed that neither sulfite nor iron alone is able to degrade SAs; however, the combined effect depends on the oxidation state of iron species whose effectiveness to activate sulfite to promote the degradation of SAs increased following this order: Fe(III) < Fe(II) < Fe(0) < Fe(VI). Using Fe(VI)/sulfite, the complete removal of SAs was obtained in 5 min largely surpassing the effectiveness of the other three systems. The sulfonamides’ removal percentage was markedly influenced by sulfite concentration and dissolved oxygen, which improved the generation of oxidant radicals. Response surface methodology was applied, and a quadratic polynomial model was obtained, which allowed us to determine the percentage of SAs degradation as a function of both the iron species and sulfite concentrations. The study of the influence of the water matrix on these AOTs revealed an inhibition of SAs’ removal percentage when using ground water. This is probably due to the presence of different anions, such as HCO3−, Cl−, and SO42− in relatively high concentrations. According to the byproducts identified, the proposed degradation pathways include hydroxylation, SO2 extrusion, and different bond-cleavage processes. Cytotoxicity of degradation byproducts, using MTS assay with HEK 293 and J774 cell lines for the first time, did not show an inhibition in cell proliferation, sustaining the safety of the process.

Influence of functional groups on toxicity of carbon nanomaterials

It has been recognized that carbon nanomaterials and soot particles are toxic for human health, but the influence of functionalization on their toxicity as well as the evolution of the toxicity of carbon nanomaterials due to chemical aging in the atmosphere is still controversial. In the current study, the oxidation potential measured by dithiothreitol (DTT) decay rate and the cytotoxicity to murine macrophage cells of different functionalized carbon nanomaterials were investigated to understand the role of functionalization in their toxicities. The DTT decay rates of special black 4A (SB4A), graphene, graphene oxide, single-walled carbon nanotubes (SWCNTs), SWCNT-OH and SWCNT-COOH were 45.9±3.0, 58.5±6.6, 160.7±21.7, 38.9±8.9, 57.0±7.2 and 36.7±0.2 pmol min−1 µg−1, respectively. Epoxide was found to be mainly responsible for the highest DTT decay rate of graphene oxide compared to other carbon nanomaterials based on comprehensive characterizations. Both carboxylation and hydroxylation showed little influence on the oxidation potential of carbon nanomaterials, while epoxidation contributes to the enhancement of oxidation potential. All these carbon nanomaterials were toxic to the murine J774 cell line. However, oxidized carbon nanomaterials (graphene oxide, SWCNT-OH and SWCNT-COOH) showed weaker cytotoxicity to the J774 cell line compared to the corresponding control sample as far as the metabolic activity was considered and stronger cytotoxicity to the J774 cell line regarding the membrane integrity and DNA incorporation. These results imply that epoxidation might enhance the oxidation potential of carbon nanomaterials.

Influence of functional groups on toxicity of carbon nanomaterials: implication for toxicological evolution during atmospheric relevant aging of soot

It has been well recognized that black carbon is toxic for human health, while it is still controversial about the influence of functionalization on its toxicity as well as the evolution of its toxicity due to chemical aging in the atmosphere. In the current study, the oxidation potential measured by dithiothreitol (DTT) decay rate and the cytotoxicity to murine macrophage cells of different functionalized carbon nanomaterials, which were used as model sample of black carbon, were investigated for understanding the role of functionalization in the toxicity of black carbon. The DTT decay rates of special black 4A (SB4A), graphene, graphene oxide, single wall carbon nanotubes (SWCNT), SWCNT-OH and SWCNT-COOH were 45.9&amp;pm;3.0, 58.5&amp;pm;6.6, 160.7&amp;pm;21.7, 38.9&amp;pm;8.9, 57.0&amp;pm;7.2 and 36.7&amp;pm;0.2 pmol min−1 μg−1, respectively. Epoxide was found to be mainly responsible for the largest DTT decay rate of graphene oxide compared with other materials based on comprehensive characterizations. Both carboxylation and hydroxylation showed little influence on the oxidation potential of these materials, while epoxidation contributes to the enhancement of oxidation potential. All these carbon nanomaterials were toxic to murine J774 cell line. However, oxidized carbon nanomaterials (graphene oxide, SWCNT-OH and SWCNT-COOH) showed weaker cytotoxicity to J774 cell line compared with the corresponding control sample as far as the metabolic activity was considered and stronger cytotoxicity to J774 cell line regarding to the membrane integrity and DNA incorporation. These results imply that epoxidation might enhance the oxidation potential of black carbon during transport in the atmosphere.

The viability of the genetically diverse C. jejuni and C. coli strains in the macrophage J774 cell line

The viability of the genetically diverse C. jejuni and C. coli strains in the macrophage J774 cell line The intracellular survival of Campylobacter has been described within epithelial cells as well as in macrophages in vitro. The goal of this study was to estimate the viability of the genetically diverse C. jejuni and C. coli strains in the macrophage J774 cell line. Strains selected for analysis differed with regard to the occurrence of genes encoding specific virulence factors. The present work indicates that was no correlation between the source of isolates and relative intracellular survival.

Cytotoxicity of Carbon Nanotubes on J774 Macrophages Is a Purification-Dependent Effect

The cytotoxicity of the carbon nanotubes (CNTs) is an important factor for the manufacture of nanovaccines. The aim of this work was to evaluate the relationship of the purification method of CNTs in cellular toxicity using macrophages (MOs) from the J774 cell line. Viability test was performed with MTT assays at 24 h of exposure at concentrations of 0.06, 0.6, and 6 mg/L of unpurified (UP-CNTs) or purified (P-CNTs) CNTs by two different methods: (1) reflux with 3M HNO3and (2) sonication in H2SO4/HNO3. Characterization and COOH content of CNTs was performed using scanning electron microscopy, raman spectroscopy, and titration with NaHCO3. P-CNTs1had lengths >100 μm and 2.76% COOH content, while P-CNTs2had lengths >1 μm and 7% COOH content. This last particle showed a lower toxic effect. The results suggest that the lenght and COOH content are important factors in the toxicity of the CNTs.