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Carbon monoxide (CO) is a highly toxic, colorless, tasteless and odorless gas. It is formed when there is incomplete combustion of organic matter. Approximately 40% of atmospheric CO comes from natural sources and the remaining 60% comes from human activities. CO can also be generated endogenously. CO intoxications are a common reality, resulting in over 50000 emergency admissions in USA. In Portugal, CO intoxications are not very common, but cannot be overlooked. CO toxicity is mainly related with its interaction with hemoglobin (Hb) forming carboxyhemoglobin (COHb) and leading to a compromise of oxygen transportation to peripheral tissues.A spectrophotometric method for quantification of COHb was validated accordingly to European Medicines Agency. The limit of detection (LOD), limit of quantification (LOQ), precision (%CV), accuracy and linearity of the method were determined. After collection, blood was mixed with sodium fluoride (NaF) 2.5% and separated in 2 tubes containing hemolysis solution – one was bubbled with oxygen and the other bubbled with CO.Appropriate amounts of these solutions were mixed in order to prepare standard solutions of known concentrations. Subsequently, all standards solutions were mixed with sodium dithionite to promote a reduction and analyzed by UV/Vis spectrophotometry at 420 and 432 nm. Linearity was verified in a concentration range from 0-100% of COHb, with r2≥0.98. The %CV intra and inter-day were below 15%. The recovery percentage ranged from 89.3- 117.3%, with a deviation of 10.1%. LOD and LOQ varied from 0.9-1.4%.In order to analyze the stability of COHb, blood samples were stored at three temperatures (room temperature (RT), 4ºC and -20ºC) and analyzed with NaF – simulating a fatal intoxication, and without NaF – simulating non-fatal intoxication. In non-fatal intoxication samples, at -20ºC and 4ºC there was no variation in COHb concentration between first analysis and posterior re-analysis. At RT there was a negative variation of 21.4% relatively to initial value. Fatal intoxicationsamples exhibited the same behavior at - 20ºC and 4ºC. At RT, there was an increase of 21.1% in comparison to initial value.In conclusion, a spectrophotometric method for %COHb quantification was validated. The %COHb did not suffer variation throughout time at -20ºC and 4ºC. RT is not a recommended storage temperature for %COHb quantification and NaF seems not to have any relevance in the stability.

In recent years, gold nanoparticles (AuNPs) have aroused the interest of many researchers due to their unique physicochemical and optical properties. AuNPs are being explored in a variety of biomedical fields, either in diagnostics or therapy, particularly for localized thermal ablation of cancer cells after light irradiation. Besides the promising therapeutic potential of AuNPs, their safety constitutes a highly important issue for any medicine or medical device. For this reason, in the present work, the production and characterization of physicochemical properties and morphology of AuNPs coated with two different materials (hyaluronic and oleic acids (HAOA) and bovine serum albumin (BSA)) were firstly performed. Based on the above importantly referred issue, the in vitro safety of developed AuNPs was evaluated in healthy keratinocytes, human melanoma, breast, pancreatic and glioblastoma cancer cells, as well as in a three-dimensional human skin model. Ex vivo and in vivo biosafety assays using, respectively, human red blood cells and Artemia salina were also carried out. HAOA-AuNPs were selected for in vivo acute toxicity and biodistribution studies in healthy Balb/c mice. Histopathological analysis showed no significant signs of toxicity for the tested formulations. Overall, several techniques were developed in order to characterize the AuNPs and evaluate their safety. All these results support their use for biomedical applications.

Tufas are freshwater carbonate rocks that form in continental environments through a combination of physical, chemical, and biological processes. This study investigates the role of microorganisms in the precipitation of Quaternary tufa deposits in the Serra da Bodoquena Formation, in the Bonito region. Two sites along the Mimoso River, named Taíka and Mimosa, characterized by the pool–barrage–cascade depositional subenvironment, were selected for this study. Four distinct facies were identified: stromatolitic boundstones, phytoherm boundstones of algae, phytoherm boundstones of bryophytes, and phytoclastic rudstones. These facies were observed in diverse hydrological settings, including fast-flowing waters, such as waterfalls and cascades, as well as slow-flowing areas, such as pools and dams. The δ18O depletion indicated a meteoric origin for the fluid involved in carbonate precipitation. The low δ13C values were attributed to photosynthetic processes and the contribution of light carbon-enriched groundwater. The presence of Oocardium stratum and calcified organic mucilage from extracellular polymeric substance (EPS) corroborates the significant role of microorganisms in tufa formation, particularly in stromatolitic boundstones and phytoherm boundstones of algae. Rapid CO2 degassing significantly contributes to mineralization in fast-flowing waters. Micro-CT results offer detailed insights into the relationship between mechanical processes and biological influences in shaping porosity characteristics. The findings of this study significantly enhance our understanding of the role of microorganisms in tufa formation, highlighting the complex interplay between biotic and abiotic processes in the development of different tufa facies. Moreover, the insights gained from this study provide valuable implications for interpreting tufa deposits worldwide.