Los microplásticos en el entorno acuático: Un vistazo a la cinética, mecanismo de degradación, impacto ambiental y en la salud humana: Microplastics in the aquatic environment: An overview of kinetics, degradation mechanism, environmental and human health impact

Desde su origen en la década de los años 50’s, los plásticos se han convertido en un material omnipresente en la vida diaria de nuestras sociedades. A pesar de su amplia gama de usos, la lenta degradación de estos materiales en el ambiente ha ocasionado un problema de contaminación emergente de consecuencias aún desconocidas. El objetivo de esta revisión es el de evaluar el impacto que ha tenido la introducción de los microplásticos en nuestros ecosistemas. Reportes recientes indican que la presencia de microplásticos se ha extendido hasta ambientes prístinos como los polos del planeta. La degradación de los materiales plásticos, en partículas de menor tamaño llamados microplásticos cuando su diámetro es menor a 5 mm y su ingesta por organismos diversos plantea la pregunta de cuál es el efecto a largo plazo en la salud de los ecosistemas. Efectos adversos en el metabolismo de microorganismos, peces y en el ser humano han sido ampliamente documentados. Igualmente, se ha reportado la capacidad de estas partículas de movilizar contaminantes ambientales como metales pesados, hidrocarburos, e incluso virus. Entre estos efectos adversos se incluyen alteraciones metabólicas, formación de especies reactivas de oxígeno y modificación de procesos inflamatorios. Podemos concluir que la presencia de las partículas de microplásticos están presentes en diversos nichos de los ecosistemas terrestres y que su degradación introduce compuestos químicos potencialmente disruptivos en ellos. Por lo que entender el origen, transformación, rol en el transporte y liberación de contaminantes en el ambiente nos permitirá diseñar estrategias para minimizarlos.Since their origin in the 1950s, plastics have become a ubiquitous material in the daily life of our societies. Despite their wide range of uses, the slow degradation of these materials in the environment has led to an emerging pollution problem with unknown consequences. The objective of this review is to assess the impact of the introduction of microplastics into our ecosystems. Recent reports indicate that microplastics have spread to pristine environments such as the planet's poles. The degradation of plastic materials into smaller particles called microplastics when their diameter is less than 5 mm and their ingestion by various organisms raises the question of is the long-term effect on ecosystem health. Adverse effects on the metabolism of microorganisms, fish, and humans have been widely documented. The ability of these particles to mobilize environmental pollutants such as heavy metals, hydrocarbons, and even viruses has also been reported. These adverse effects include metabolic alterations, formation of reactive oxygen species, and modification of inflammatory processes. We can conclude that microplastic particles are present in various niches of terrestrial ecosystems and that their degradation introduces potentially disruptive chemical compounds into them. Understanding the origin, transformation, and role in transporting and releasing pollutants into the environment will allow us to design strategies to minimize them

Fatty acid conjugates of Toluidine Blue O as Amphiphilic Photosensitizers: Synthesis, solubility, photophysics and photochemical properties(dagger)

Toluidine blue O (TBO) is a water-soluble photosensitizer that has been used in photodynamic antimicrobial and anticancer treatments, but suffers from limited solubility in hydrophobic media. In an effort to incrementally increase TBO's hydrophobicity, we describe the synthesis of hexanoic (TBOC6) and myristic (TBOC14) fatty acid derivatives of TBO formed in low to moderate percent yields by condensation with the free amine site. Covalently linking 6 and 14 carbon chains led to modifications of not only TBO's solubility, but also its photophysical and photochemical properties. TBOC6 and TBOC14 derivatives were more soluble in organic solvents and showed hypsochromic shifts in their absorption and emission bands. The solubility in phosphate buffer solution was low for both TBOC6 and TBOC14, but unexpectedly slightly greater in the latter. Both TBOC6 and TBOC14 showed decreased triplet excited-state lifetimes and singlet oxygen quantum yields in acetonitrile, which was attributed to heightened aggregation of these conjugates particularly at high concentrations due to the hydrophobic "tails." While in diluted aqueous buffer solution, indirect measurements showed similar efficiency in singlet oxygen generation for TBOC14 compared to TBO. This work demonstrates a facile synthesis of fatty acid TBO derivatives leading to amphiphilic compounds with a delocalized cationic "head" group and hydrophobic "tails" for potential to accumulate into biological membranes or membrane/aqueous interfaces in PDT applications.CONICYT through their FONDECYT research program 1160443 CONICYT/FONDEQUIP/UHPLC-MS/MS EQM 120065 ANID FONDECYT/POSTDOCTORADO 3200403 National Science Foundation (NSF) CHE-1856765 CONICYT/FONDEQUIP/Laser Flash Photolysis EQM160099 CONICYT-PCHA/Doctorado Nacional/2015-2115089

Mechanism of Visible-Light Photooxidative Demethylation of Toluidine Blue O

Experiments and theoretical calculations by density functional theory (DFT) have been carried out to examine a self-sensitized type I photooxidation of toluidine blue O (TBO+). This study attempts to build a connection between visible-light photolysis and demethylation processes of methylamine compounds, such as TBO+. We show that controlled photoinduced mono- and double-demethylation of TBO+ can be achieved. The kinetics for the appearance rate of the mono-demethylated TBO+ and the double-demethylated TBO+ were found to fit pseudo-first-order kinetics. DFT calculations have been used to examine the demethylation of TBO+ and included N,N-dimethylaniline as a model compound for TBO+. The results show an oxygen-dependent demethylation process. The mechanism for the sequential methyl loss is proposed to be due to H• or e-/H+ transfer to 3TBO+∗ followed by a reaction of TBO+• with O2, yielding a C-peroxyTBO+• intermediate. Instead of aminyl radical peroxyl formation, i.e., N-peroxyTBO+•, the C-centered peroxyTBO+• is favored, that upon dimerization (Russell mechanism) leads to dissociation of formaldehyde from the methylamine site

Supramolecular reversible On-Off switch for singlet oxygen using cucurbit[n]uril inclusion complexes

A novel strategy to control the generation of singlet oxygen by a photosensitizer using cucurbit[n]urils inclusion complexes is shown herein, and the strategy has great potential for therapeutic applications. We show the basic requirements of the photosensitizer complexes in order to develop an on off switch for singlet oxygen that is reversible using competitive binding. The supramolecular strategy proposed in this paper avoids complex synthetic schemes in order to activate or deactivate the photosensitizer as previous work has shown and supports the use of biocompatible materials. Mechanistic insights into the control over the generation of singlet oxygen are provided, which strongly emphasize the key role of the cucurbit[n]uril macrocycles in the stabilization or deactivation of the triplet excited state.CONICYT through FONDECYT research program 1160443 CONICYT PCHA/Doctorado Nacional/2015-21150894 ICM Grant 120082 supercomputing infrastructure of the NLHPC ECM-0

The issue of micro and nanoplastics on the American coasts of the Pacific Ocean

Este trabajo aborda la problemática representada por los micro y nanoplásticos (MP y NP, respectivamente) en las costas americanas del Océano Pacífico, desde la perspectiva de la Red Micro y Nano Allpa Pacha. Esta red está conformada por científicos de Chile, Perú, Costa Rica, Colombia, Ecuador, Panamá y México, quienes, preocupados por el impacto en el ambiente y su repercusión en la salud, decidieron establecer colaboraciones científicas internacionales para la geolocalización, monitoreo y caracterización de MP y NP presentes en las costas del Océano Pacífico en el continente americano. Se espera aportar datos basados en evidencias científicas y armonizados, que impacten en la enseñanza y en la planificación de medidas de control y regulación de estos contaminantes en nuestros países. En este trabajo se incluyen algunos aspectos de polímeros y plásticos, definiciones de MP’s y NP’s, y sus diversos impactos, la problemática de la toma de muestras, caracterización adecuada, entre otros. Unas de las conclusiones permitieron determinar que hay muchas características de los NP’s y MP’s sin investigar como la interacción con otros productos químicos, el impacto de la morfología en la biodisponibilidad, la formación de adherencias y liberación de las mismas durante su contacto con los compartimentos ambien- tales, la dependencia de su composición con su comportamiento y destino, entre otras. Asimismo, se determinó que todo aporte a la mitigación del problema de estos materiales debe incluir la concientización, la prevención y la reducción, mediante un enfoque integral de educación y capacitación, y considerando todos los actores de la sociedad, responsables de la problemática generada, bajo un enfoque de evidencia científica. Finalmente, se determinó que el tema aún está en su fase inicial, y la información es reiterativa y auto referenciadaThis work addresses the micro and nanoplastics (MP and NP, respectively) on the American coasts of the Pacific Ocean from the perspective of the Micro & Nano Allpa Pacha Network. This network is made up of scientists from Chile, Perú, Costa Rica, Colombia, Ecuador, Panama, and Mexico, who, concerned about the impact on the environment and its repercussions on health, decided to establish international scientific collaborations for the geolocation, monitoring, and characterization of MP and NP present on the coasts of the Pacific Ocean in the American continent. It is expected to provide data based on harmonized scientific evidence, which will impact the teaching and planning of control and regulation measures for these pollutants in our countries. This work includes some aspects of polymers and plastics, definitions of MP’s and NP’s and their various impacts, the problem of taking samples, adequate characterization, among others. One of the conclusions determined that are many characteristics of NP’s and MP’s without investigating, such as interaction with other chemical products, the impact of morphology on bioavailability, formation of adhesions and their release during their contact with environmental compartments, the dependence of its composition with its behavior and destiny, among others. Likewise, it was determined that any contribution to mitigating the problem of these materials must include awareness, prevention, and reduction through a comprehensive approach to education and training and considering all actors in society responsible for the problem generated under a scientific evidence approach. Finally, it was determined that the issue is still in its initial phase, and the information is repetitive and self-reference