Biotransformation of Metal-Rich Effluents and Potential Recycle Applications

In this chapter, it was introduced about the metallurgic effluents, and their potential to be converted into some feasible coproducts for industries. Some possibilities to introduce circular economy in the context of metallurgic effluents, and in the same way, some techniques to promote bioremediation using microorganisms and products from them were also described. Reported studies, as well as some perspectives to use metal-rich effluents in agriculture and soil quality improvement, were also shown. Copper effluents were kept as the main candidate for sustainable use, as a potentially interesting material for circular economy approaches

Evaluation of the photodynamic activity of Xanthene Dyes on Artemia salina described by chemometric approaches

The development of drugs for photodynamic therapy (PDT) is an important area of research due to their growing use in medical applications. Therefore, it is important to develop new bioassay methods for PDT photosensitizers that are inexpensive, easy to handle and highly sensitive to environmental conditions. Xanthene dyes (fluorescein, rose bengal B, erythrosine B and eosin Y) with LED light sources were investigated using Artemia salina as a bioindicator of photodynamic activity. In this study, three factors were investigated: (i) photosensitizers concentration, (ii) the LED irradiation time and (iii) the waiting time between the addition of the photosensitizers and the beginning of the irradiation. To analyze the photo-killing of A. salina, it was employed a 23 full factorial design. The death of A. salina was related to dye structure and the interaction between the irradiation time and the photosensitizers concentration. About 60% of crustaceans death was obtained using rose bengal B, which presentes the highest quantum yield of singlet oxygen due to the number of iodide substituents in the xanthenes ring. The proposed bioassay using A. salina, xanthene dyes and LED irradiation was found suitable for quantitative PDT drug evaluation

Distribution of Xanthene Dyes in DPPC Vesicles: Rationally Accounting for Drug Partitioning Using a Membrane Model

The correct selection of a dye that has effective action as a photosensitizer is a primary concern for successful therapeutic outcomes. The effectiveness of the photodynamic agent is related to both the targeting of cell membranes and the photochemical yield of the chosen dye. The distributions of xanthene derivatives Eosin Y, Erythrosin B, and Rose Bengal B in vesicles of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) in both liquid-crystalline and gel phases were investigated by fluorescence spectroscopy. Binding constants, fluorescence anisotropy, fluorescence quenching, fluorescence quantum yield, and fluorescence resonance energy transfer at physiological pH conditions were determined. To Erythrosin B and Eosin Y, the iodide quenching rate constant was shown to involve a sphere of action mechanism driven by a specific interaction between Erythrosin B and Eosin Y molecules and the choline head-group of the phospholipid; in contrast, Rose Bengal B was located deep in the membrane and this mechanism was not present. The dyes can be ordered by their penetration depth in the membrane, and this order was found to be Eosin Y < Erythrosin B < Rose Bengal B. These results demonstrate a rational approach for the screening of more active agents for photodynamic therapy based on the affinity between the xanthene derivatives and DPPC vesicles

Distribution of Xanthene Dyes in DPPC Vesicles: Rationally Accounting for Drug Partitioning Using a Membrane Model

The correct selection of a dye that has effective action as a photosensitizer is a primary concern for successful therapeutic outcomes. The effectiveness of the photodynamic agent is related to both the targeting of cell membranes and the photochemical yield of the chosen dye. The distributions of xanthene derivatives Eosin Y, Erythrosin B, and Rose Bengal B in vesicles of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) in both liquid-crystalline and gel phases were investigated by fluorescence spectroscopy. Binding constants, fluorescence anisotropy, fluorescence quenching, fluorescence quantum yield, and fluorescence resonance energy transfer at physiological pH conditions were determined. To Erythrosin B and Eosin Y, the iodide quenching rate constant was shown to involve a sphere of action mechanism driven by a specific interaction between Erythrosin B and Eosin Y molecules and the choline head-group of the phospholipid; in contrast, Rose Bengal B was located deep in the membrane and this mechanism was not present. The dyes can be ordered by their penetration depth in the membrane, and this order was found to be Eosin Y &lt; Erythrosin B &lt; Rose Bengal B. These results demonstrate a rational approach for the screening of more active agents for photodynamic therapy based on the affinity between the xanthene derivatives and DPPC vesicles

Micro-Addition of Silver to Copper: One Small Step in Composition, a Change for a Giant Leap in Biocidal Activity

The use of copper as an antimicrobial agent has a long history and has gained renewed interest in the context of the COVID-19 pandemic. In this study, the authors investigated the antimicrobial properties of an alloy composed of copper with a small percentage of silver (Cu-0.03% wt.Ag). The alloy was tested against various pathogens, including Escherichia coli, Staphylococcus aureus, Candida albicans, Pseudomonas aeruginosa, and the H1N1 virus, using contact exposure tests. Results showed that the alloy was capable of inactivating these pathogens in two hours or less, indicating its strong antimicrobial activity. Electrochemical measurements were also performed, revealing that the small addition of silver to copper promoted a higher resistance to corrosion and shifted the formation of copper ions to higher potentials. This shift led to a slow but continuous release of Cu2+ ions, which have high biocidal activity. These findings show that the addition of small amounts of silver to copper can enhance its biocidal properties and improve its effectiveness as an antimicrobial material