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The bioinorganic chemistry of chromium
Chromium exists in nature as complexes of two stable oxidation states – trivalent chromium(III) and hexavalent chromium(VI). Although trivalent chromium is required in trace amounts for sugar and lipid metabolism in humans and its deficiency may cause a disease called chromium deficiency; hexavalent chromium is toxic and carcinogenic. As chromium compounds were used in dyes and paints and the tanning of leather, these compounds are often found in soil and groundwater at abandoned industrial sites, now needing environmental cleanup and remediation.
The Bioinorganic Chemistry of Chromium: From Biochemistry to Environmental Toxicology takes a critical look at what the biochemical data indicate about chromium's role in the body and the biological mechanisms of its toxicology. Topics covered include:
* What do we know about the biochemical roles and mechanisms of chromium?
* Is chromium an essential element in the mammalian diet?
* Is chromium(III) effective as a nutraceutical, a therapeutic agent, and as a supplement in animal feed?
* What is the biochemistry behind the toxicology of chromium(III) and chromium(VI):the mechanisms of metabolism, genetic and epigenetic effects, and disruption of cell signalling?
* What are the current chromium(VI) policies and positions from regulatory agencies?
The Bioinorganic Chemistry of Chromium: From Biochemistry to Environmental Toxicology is an important contribution to the bioinorganic and trace element biochemical fields which will find a place on the bookshelves of bioinorganic chemists, biochemists, inorganic chemists, toxicologists, nutritionists and regulatory affairs professionals.
eBook
Construction of SnO.sub.2@CrS.sub.2 Nanocuboids Via Solvothermal Synthesis for Photoelectrochemical OER/HER Performance in Alkaline and Acidic Media and Water Detoxification Behavior
The electrolytic division of water into hydrogen (H.sub.2) and oxygen (O.sub.2) presents a sustainable solution for meeting escalating demands in renewable energy sources. Yet, this process faces formidable challenges due to its energy-intensive nature. Our study introduces efficient electrocatalysts formed from chromium sulphide nanoparticles integrated with tin oxide via a straightforward solvothermal approach, enabling water splitting in both acidic and alkaline settings. The resulting SnO.sub.2@CrS.sub.2 heterostructure exhibits notable performance by requiring lower overpotentials 142 and 99 mV for achieving a current density of 10 mA cm.sup.-2 during the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) in 1 M KOH, and 157 and 165 mV for OER and HER in 0.1 M HClO.sub.4, respectively. Correspondingly, Tafel slopes of 30 and 45 mVdec.sup.-1 in 1.0 M KOH and 52 and 32 mVdec.sup.-1 in 0.1 M HClO.sub.4 were observed for OER and HER respectively. These catalysts display promising efficiency at reduced overpotentials, demonstrating exceptional performance for overall water splitting. This approach of integrating an active heterostructure through interfacial tuning offers a novel pathway for developing economically viable and efficient electrocatalyst systems crucial for water splitting and H.sub.2 production.
Journal Article
Genotoxicity of Tri- and Hexavalent Chromium Compounds In Vivo and Their Modes of Action on DNA Damage In Vitro
Chromium occurs mostly in tri- and hexavalent states in the environment. Hexavalent chromium [Cr(VI)] compounds are extensively used in diverse industries, and trivalent chromium [Cr(III)] salts are used as micronutrients and dietary supplements. In the present work, we report that they both induce genetic mutations in yeast cells. They both also cause DNA damage in both yeast and Jurkat cells and the effect of Cr(III) is greater than that of Cr(VI). We further show that Cr(III) and Cr(VI) cause DNA damage through different mechanisms. Cr(VI) intercalates DNA and Cr(III) interferes base pair stacking. Based on our results, we conclude that Cr(III) can directly cause genotoxicity in vivo.
Journal Article
Is the Pharmacological Mode of Action of Chromium(III) as a Second Messenger?
Although recent studies have shown that chromium (as the trivalent ion) is not an essential trace element, it has been demonstrated to generate beneficial effects at pharmacologically relevant doses on insulin sensitivity and cholesterol levels of rodent models of insulin insensitivity, including models of type 2 diabetes. The mode of action of Cr(III) at a molecular level is still an area of active debate; however, the movement of Cr(III) in the body, particularly in response to changes in insulin concentration, suggests that Cr(III) could act as a second messenger, amplifying insulin signaling. The evidence for the pharmacological mechanism of Cr(III)’s ability to increase insulin sensitivity by acting as a second messenger is reviewed, and proposals for testing this hypothesis are described.
Journal Article
Chromium toxicity, speciation, and remediation strategies in soil-plant interface: A critical review
In recent decades, environmental pollution with chromium (Cr) has gained significant attention. Although chromium (Cr) can exist in a variety of different oxidation states and is a polyvalent element, only trivalent chromium [Cr(III)] and hexavalent chromium [Cr(VI)] are found frequently in the natural environment. In the current review, we summarize the biogeochemical procedures that regulate Cr(VI) mobilization, accumulation, bioavailability, toxicity in soils, and probable risks to ecosystem are also highlighted. Plants growing in Cr(VI)-contaminated soils show reduced growth and development with lower agricultural production and quality. Furthermore, Cr(VI) exposure causes oxidative stress due to the production of free radicals which modifies plant morpho-physiological and biochemical processes at tissue and cellular levels. However, plants may develop extensive cellular and physiological defensive mechanisms in response to Cr(VI) toxicity to ensure their survival. To cope with Cr(VI) toxicity, plants either avoid absorbing Cr(VI) from the soil or turn on the detoxifying mechanism, which involves producing antioxidants (both enzymatic and non-enzymatic) for scavenging of reactive oxygen species (ROS). Moreover, this review also highlights recent knowledge of remediation approaches i.e., bioremediation/phytoremediation, or remediation by using microbes exogenous use of organic amendments (biochar, manure, and compost), and nano-remediation supplements, which significantly remediate Cr(VI)-contaminated soil/water and lessen possible health and environmental challenges. Future research needs and knowledge gaps are also covered. The review’s observations should aid in the development of creative and useful methods for limiting Cr(VI) bioavailability, toxicity and sustainably managing Cr(VI)-polluted soils/water, by clear understanding of mechanistic basis of Cr(VI) toxicity, signaling pathways, and tolerance mechanisms; hence reducing its hazards to the environment.
Journal Article
Chromium speciation in solid matrices and regulation: a review
In recent years, the extensive use of chromium in industrial processes has led to the promotion of several directives and recommendations by the European Union, that try to limit and regulate the presence of Cr(VI) in the environment and to protect industrial workers using chromium and end-users of manufactured products. As a consequence, new standard methods and analytical procedures have been published at the EU level for Cr(VI) determination in soil, sludge, sediment, and similar waste materials, workplace atmospheres, cement, packaging materials, industrially produced samples, and corrosion-protection layers on some components of vehicles and electrical and electronic equipment. The objective of this article is to summarize the different directives and recommendations and to critically review the currently existing standard methods and the methods published in the literature for chromium speciation in the above mentioned solid matrices, putting the emphasis on the different extraction procedures which have been developed for each matrix. Particular attention has been paid to Cr(III) and Cr(VI) inter-conversions that can occur during extraction and efforts to minimize these unwanted reactions. Although the use of NaOH-Na₂CO₃ solutions with hot plate extraction seems to be the more widespread procedure, species transformation can still occur and several studies suggest that speciated isotope-dilution mass spectrometry (SIDMS) could be a suitable tool for correction of these interconversions. Besides, recent studies have proved the role of Cr(III) in chromium toxicology. As a consequence, the authors suggest an update of standard methods in the near future.
Journal Article
Kinetics and Mechanism of Electrochemical Reactions Occurring during the Chromium Electrodeposition from Electrolytes Based on Cr(III) Compounds: A Literature Review
A literature review was conducted to examine the current understanding of the kinetics and mechanism of electrochemical reactions occurring during the electrodeposition of chromium coatings from electrolytes based on trivalent chromium compounds. The research in this scientific field is crucial, as it addresses the pressing need for an alternative to chromium plating processes that rely on solutions containing highly toxic and harmful hexavalent chromium compounds. Numerous literature data on the kinetics and mechanism of the stepwise reduction process of Cr(III) complex ions were analyzed. The influence of various additives and surfactants on the reaction kinetics of the stepwise reduction of trivalent chromium ions was considered. Special attention was given to the kinetics of the stepwise discharge of trivalent chromium ions in ionic liquids and deep eutectic solvents.
Journal Article
Evolution of interlayer and intralayer magnetism in three atomically thin chromium trihalides
We conduct a comprehensive study of three different magnetic semiconductors, CrI₃, CrBr₃, and CrCl₃, by incorporating both few-layer and bilayer samples in van der Waals tunnel junctions. We find that the interlayer magnetic ordering, exchange gap, magnetic anisotropy, and magnon excitations evolve systematically with changing halogen atom. By fitting to a spin wave theory that accounts for nearest-neighbor exchange interactions, we are able to further determine a simple spin Hamiltonian describing all three systems. These results extend the 2D magnetism platform to Ising, Heisenberg, and XY spin classes in a single material family. Using magneto-optical measurements, we additionally demonstrate that ferromagnetism can be stabilized down to monolayer in more isotropic CrBr₃, with transition temperature still close to that of the bulk.
Journal Article