Solar Degradation of Sulfamethazine Using rGO/Bi Composite Photocatalysts

This work was supported by the Spanish Ministry of Economy, Industry and Competitiveness and by FEDER (CTQ2016-80978-C2−1-R), and the authors thank to Dr. Isabel Guerra Tschuschke for the technical advice during the VP-SEM study at the CIC-UGR.Heterogeneous photocatalysts for water decontamination were obtained by the optimized synthesis of bismuth-functionalized reduced graphene oxide (rGO/Bi) using the Hummer method and microwave treatment. Sulfamethazine (SMZ) was used as model pollutant to evaluate the photocatalytic efficacy. Photocatalysts were characterized by VP-SEM, HRTEM, XDR, XPS, RAMAN, and FTIR analyses, which confirmed the effective reduction of GO to rGO and the presence of bismuth as a crystalline phase of Bi2O3 polydispersed on the surface. Their performance was influenced by the rGO/Bi ratio, microwave temperature, and treatment time. The as-obtained 5%rGO/Bi composite had the highest photocatalytic activity for SMZ degradation under visible light irradiation (λ > 400 nm), achieving 100% degradation after only 2 h of treatment. The degradation yield decreased with higher percentages of rGO. Accordingly, the rGO/Bi catalysts efficiently removed SMZ, showing a high photocatalytic activity, and remained unchanged after three treatment cycles; furthermore, cytotoxicity tests demonstrated the nontoxicity of the aqueous medium after SMZ degradation. These findings support the potential value of these novel composites as photocatalysts to selectively remove pollutants in water treatment plants.Spanish Ministry of Economy, Industry and Competitiveness CTQ2016-80978-C2-1-REuropean Union (EU) CTQ2016-80978-C2-1-

Methotrexate Gold Nanocarriers: Loading and Release Study: Its Activity in Colon and Lung Cancer Cells

In the present study, the synthesis of gold nanoparticles (AuNPs) loaded with methotrexate (MTX) has been carried out in order to obtain controlled size and monodispersed nanocarriers of around 20 nm. The characterization study shows metallic AuNPs with MTX polydispersed on the surface. MTX is linked by the replacement of citrate by the MTX carboxyl group. The drug release profiles show faster MTX release when it is conjugated, which leads to the best control of plasma concentration. Moreover, the enhanced release observed at pH 5 could take advantage of the pH gradients that exist in tumor microenvironments to achieve high local drug concentrations. AuNP–MTX conjugates were tested by flow cytometry against lung (A-549) and colon (HTC-116) cancer cell lines. Results for A-549 showed a weaker dose–response e ect than for colon cancer ones. This could be related to the presence of folate receptors in line HTC-116 in comparison to line A-549, supporting the specific uptake of folate-conjugated AuNP–MTX by folate receptor positive tumor cells. Conjugates exhibited considerably higher cytotoxic e ects compared with the e ects of equal doses of free MTX. Annexin V-PI tests sustained the cell death mechanism of apoptosis, which is normally disabled in cancer cells.Spanish GovernmentJunta de Andalucía P18-RT-419

Dissolution and biodurability of mineral fibres

Dissolution rates of mineral fibres in several environments are obtained as proxies for their biodurability in body fluids. This chapter provides a description of the experimental methods, the parameters and characteristics to be fixed during the design of dissolution experiments in closed (batch reactors) and open systems (flow-through cells), as well as details of the dissolution media. The dissolution of mineral fibres in buffered inorganic solutions is the key to understanding their behaviour during weathering processes because it contributes not only to their chemical transformation, but also to the breakdown of the fibres that may be dispersed in the environment. On the other hand, preparation of fluids representing different interstitial conditions in the lung is described, with particular attention to artificial lysosomal fluid (ALF) employed to mimic the environment that inhaled particles would encounter after phagocytosis by alveolar and interstitial macrophages. Moreover, the use of a neutral fluid such as Gamble’s solution (GS) simulates the interstitial lung fluid and airway lining fluid. Finally, the results of studies of mineral fibre dissolution in inorganic and body fluids, found in the literature, are discussed. Methodologies for assessing the biodurability of fibres are illustrated, starting from dissolution rate data and focus on in vitro studies. Rate constants are used to assess fibre lifetimes utilizing a fibre-shrinking model equation. Finally, literature studies show differences in biopersistence between serpentine and amphibole asbestos, due to their different crystal structures and dissolution conditions of pH and solution composition