Green synthesis of silver nanoparticles (AgNPs) from G. stearothermophilus GF16: stable and versatile nanomaterials with antioxidant, antimicrobial, and catalytic properties.

Background: Silver nanoparticles (AgNPs) have attracted considerable interest for their distinctive physicochemical properties and wide-ranging applications in nanomedicine, environmental catalysis, and antimicrobial applications. However, sustainable and robust biosynthesis methods remain a challenge.

Results: In this study, we report the biosynthesis of thermostable AgNPs using the secretome of Geobacillus stearothermophilus GF16, a thermophilic and metal-resistant bacterium isolated from the hydrothermal volcanic area of Pisciarelli, Italy.

Biotechnological Potential of a Novel Strain of Fusarium proliferatum, a Terrestrial Fungus Adapted to Marine Environment.

Marine habitats represent hostile environments for the majority of microorganisms. Nonetheless, in the last decades, the study of the microbial diversity of the halophylic environments has reported that fungi constitute a quantitatively relevant component. The research reports the isolation of a novel strain of Fusarium proliferatum from seawater, within a monitoring campaign conducted in the South Calabrian coasts (Regione Calabria, Italy): the microorganism presumably adapted from a terrestrial to a marine niche, potentially changing its metabolism in response to the environmental stress.

Masks and gloves: The silent impact of pandemic waste on marine life.

The SARS-CoV-2 pandemic has determined a global health crisis. To control its spread, countries implemented several measures including social distancing and mask-wearing. Single-use face masks, gloves, and face shields made from various synthetic materials can significantly accumulate in the marine environment, along with other substances such as plasticizers, lubricants, and stabilizers, many of which are classified as contaminants of emerging concern (CECs).

Hydrogen Atom Transfer-Based C(sp)-H Bond Oxygenation of Lactams and Cycloalkenes: The Influence of Ring Size on Reactivity and Site Selectivity.

Kinetic and product studies on the reactions of the cumyloxyl (CumO) and -butoxyl (BuO) radicals with secondary and tertiary -methyl and -benzyl lactams and with cycloalkenes, accompanied by BDE calculations of the substrate C-H bonds involved in these reactions, are reported. Within the lactams, the rate constants for HAT () from the C-H bonds to CumO decrease by a factor ∼4 going from the 5- and 6-membered derivatives to the 8-membered ones. Product distributions obtained through oxygenation initiated by BuO show that HAT preferentially occurs from the most electron-rich α-C-H bonds, with site selectivity that, within the -methyl and -benzyl series, progressively shifts from the endocyclic to the exocyclic α-C-H bonds with increasing ring size, indicative of deactivation of the former bonds that, for the 8-membered derivatives, translates into competitive oxygenation at different sites.

Microplastics, microfibers and associated microbiota biofilm analysis in seawater, a case study from the Vesuvian Coast, southern Italy.

The growing concerns regarding pollution from microplastics (MPs) and microfibers (MFs) have driven the scientific community to develop new solutions for monitoring ecosystems. However, many of the proposed technologies still include protocols for treating environmental samples that may alter plastic materials, leading to inaccurate results both in observation and in counting. For this reason, we are refining a protocol, based on optical microscopy without the use of pretreatments, applicable to different environmental matrices, which allows not only counting but also a complete morphological characterization of MPs and MFs.

Can biodegradable plastics mitigate plastamination? Feedbacks from marine organisms.

The EU plastic strategy aims to reduce the environmental impact of the increasing plastic production, by replacing petrochemical-based polymers with biodegradable ones. But this mitigation measure for the plastamination might, in turn, generate bio-based microplastics in environments that are not necessarily safe. Biodegradable and non-biodegradable plastics, polylactic acid (PLA) and polypropylene (PP) respectively, and their leachates were used for testing microplastic (MP) effects on seven marine species from different trophic levels, including bacteria, algae, rotifers, copepods, amphipods and branchiopods.

Low-intensity magnetization pretreatment to enhance biomethane generation and the abundance of key microorganisms for anaerobic digestion of sewage sludge.

This work explores the impact of static magnetic field (SMF) intensity on biomethane production from anaerobic digestion (AD) of sewage sludge. Two different SMF intensities (20 mT and 1.5 T) were applied to magnetize the sludge destined to the AD process.

Radical and Cationic Pathways in C()-H Bond Oxygenation by Dioxiranes of Bicyclic and Spirocyclic Hydrocarbons Bearing Cyclopropane Moieties.

A product and DFT computational study on the reactions of 3-ethyl-3-(trifluoromethyl)dioxirane (ETFDO) with bicyclic and spirocyclic hydrocarbons bearing cyclopropyl groups was carried out. With bicyclo[.1.

Antioxidant Activities of Hydroxylated Naphthalenes: The Role of Aryloxyl Radicals.

Herein is delineated a first systematic framework for the definition of structure-antioxidant property relationships in the dihydroxynaphthalene (DHN) series. The results obtained by a combined experimental and theoretical approach revealed that 1,8-DHN is the best performing antioxidant platform, with its unique hydrogen-bonded peri-hydroxylation pattern contributing to a fast H atom transfer process. Moreover, the comparative analysis of the antioxidant properties of DHNs carried out by performing DPPH and FRAP assays and laser flash photolysis experiments, revealed the higher antioxidant power associated with an α-substitution pattern (i.

Factors Governing Reactivity and Selectivity in Hydrogen Atom Transfer from C(sp)-H Bonds of Nitrogen-Containing Heterocycles to the Cumyloxyl Radical.

A kinetic study of the hydrogen atom transfer (HAT) reactions from nitrogen-containing heterocycles (secondary and tertiary lactams, 2-imidazolidinones, 2-oxazolidinones, and succinimides) to the cumyloxyl radical has been carried out employing laser flash photolysis with ns time resolution. HAT occurs from the C-H bonds that are α to nitrogen, activated by hyperconjugative overlap with the N-C═O π system. In the lactam series, the second-order HAT rate constant () was observed to decrease by a factor of ∼4 going from the five- and six-membered ring derivatives to the eight-membered ones, a behavior that was rationalized on the basis of a reduced extent of hyperconjugative activation associated to the greater flexibility of the larger rings compared to the smaller ones.

Resolving Oxygenation Pathways in Manganese-Catalyzed C(sp)-H Functionalization via Radical and Cationic Intermediates.

The C(sp)-H bond oxygenation of the cyclopropane-containing mechanistic probes 6--butylspiro[2.5]octane and spiro[2.5]octane with hydrogen peroxide catalyzed by manganese complexes bearing aminopyridine tetradentate ligands has been studied.

Exposure of Buffalo Milkers to Pathogenic Bacteria and Characterization of Isolated Methicillin-Resistant spp.

The research was focused on the surveillance of the exposure of buffalo milkers in contact with both animals and potentially contaminated equipment, pointing attention on the diffusion of antibiotic-resistant spp. The monitoring was performed for 12 months, allowing the collection of 600 raw milk and buffalo udder surface samples, 192 milking lanes, 400 milking clusters, 160 personal protective equipment (PPEs) and electronic devices surface samples in contact with the workers of four milking parlors located in Southern Italy. The analysis of the milk samples evidenced the highest exposure to the bacteria considered (and mainly to ) from late winter-spring seasons onward.

Electronic control over site-selectivity in hydrogen atom transfer (HAT) based C(sp)-H functionalization promoted by electrophilic reagents.

The direct functionalization of C(sp)-H bonds represents one of the most investigated approaches to develop new synthetic methodology. Among the available strategies for intermolecular C-H bond functionalization, increasing attention has been devoted to hydrogen atom transfer (HAT) based procedures promoted by radical or radical-like reagents, that offer the opportunity to introduce a large variety of atoms and groups in place of hydrogen under mild conditions. Because of the large number of aliphatic C-H bonds displayed by organic molecules, in these processes control over site-selectivity represents a crucial issue, and the associated factors have been discussed.

Bimodal Evans-Polanyi Relationships in Hydrogen Atom Transfer from C(sp)-H Bonds to the Cumyloxyl Radical. A Combined Time-Resolved Kinetic and Computational Study.

The applicability of the Evans-Polanyi (EP) relationship to HAT reactions from C(sp)-H bonds to the cumyloxyl radical (CumO) has been investigated. A consistent set of rate constants, , for HAT from the C-H bonds of 56 substrates to CumO, spanning a range of more than 4 orders of magnitude, has been measured under identical experimental conditions. A corresponding set of consistent gas-phase C-H bond dissociation enthalpies (BDEs) spanning 27 kcal mol has been calculated using the (RO)CBS-QB3 method.

Deciphering Reactivity and Selectivity Patterns in Aliphatic C-H Bond Oxygenation of Cyclopentane and Cyclohexane Derivatives.

A kinetic, product, and computational study on the reactions of the cumyloxyl radical with monosubstituted cyclopentanes and cyclohexanes has been carried out. HAT rates, site-selectivities for C-H bond oxidation, and DFT computations provide quantitative information and theoretical models to explain the observed patterns. Cyclopentanes functionalize predominantly at C-1, and tertiary C-H bond activation barriers decrease on going from methyl- and -butylcyclopentane to phenylcyclopentane, in line with the computed C-H BDEs.

Practical and Selective sp C-H Bond Chlorination via Aminium Radicals.

The introduction of chlorine atoms into organic molecules is fundamental to the manufacture of industrial chemicals, the elaboration of advanced synthetic intermediates and also the fine-tuning of physicochemical and biological properties of drugs, agrochemicals and polymers. We report here a general and practical photochemical strategy enabling the site-selective chlorination of sp C-H bonds. This process exploits the ability of protonated N-chloroamines to serve as aminium radical precursors and also radical chlorinating agents.

Hydrogen atom transfer from 1,2- and 1,3-diols to the cumyloxyl radical. The role of structural effects on metal-ion induced C-H bond deactivation.

Strong C-H bond deactivation toward HAT has been observed in the reactions of the cumyloxyl radical with 1,2- and 1,3-diols, following addition of Li and Ca. Weaker effects have been observed with Mg. The role of the substrate structure and of the metal ion in the formation of Lewis acid-base complexes is discussed.

Evaluation of Polar Effects in Hydrogen Atom Transfer Reactions from Activated Phenols.

Evaluation of polar effects in hydrogen atom transfer (HAT) processes is made difficult by the fact that in most cases substrates characterized by lower bond dissociation energies (BDEs), activated from an enthalpic point of view, are also more activated by polar effects. In search of an exception to this general rule, we found that the introduction of a methoxy substituent in the 3-position of 2,6-dimethylphenol results in a small increase in the O-H BDE and a decrease of the ionization potential of the phenol. These findings suggest that the enthalpic effect associated with the addition of the m-methoxy group to 2,6-dimethylphenol will decrease reaction rates, while the polar effects will increase reaction rates.

The Quest for Selectivity in Hydrogen Atom Transfer Based Aliphatic C-H Bond Oxygenation.

Aliphatic C-H bond functionalization is at the frontline of research because it can provide straightforward access to simplified and cost-effective synthetic procedures. A number of these methodologies are based on hydrogen atom transfer (HAT), which, as a consequence of the inert character of C-H bonds, often represents the most challenging step of the overall process. Because the majority of organic molecules contain multiple nonequivalent C-H bonds that display similar chemical properties, differentiating between these bonds with high levels of selectivity represents one of the most challenging issues.

Hydrogen Atom Transfer from Alkanols and Alkanediols to the Cumyloxyl Radical: Kinetic Evaluation of the Contribution of α-C-H Activation and β-C-H Deactivation.

A kinetic study on the reactions of the cumyloxyl radical (CumO) with a series of alkanols and alkanediols has been carried out. Predominant hydrogen atom transfer (HAT) from the α-C-H bonds of these substrates, activated by the presence of the OH group, is observed. The comparable k values measured for ethanol and 1-propanol and the increase in k measured upon going from 1,2-diols to structurally related 1,3- and 1,4-diols is indicative of β-C-H deactivation toward HAT to the electrophilic CumO, determined by the electron-withdrawing character of the OH group.

Characterization and Fate of Hydrogen-Bonded Free-Radical Intermediates and Their Coupling Products from the Hydrogen Atom Transfer Agent 1,8-Naphthalenediol.

1,8-Naphthalenediol (dihydroxynaphthalene, 1,8-DHN) has been shown to be a potent hydrogen atom transfer (HAT) antioxidant compound because of the strong stabilization of the resulting free radical by intramolecular hydrogen bonding. However, the properties, reactivity, and fate of the 1,8-DHN phenoxyl radical have remained so far uncharted. Herein, we report an integrated experimental and computational characterization of the early intermediates and dimer products that arise by the oxidation of 1,8-DHN.

Enhancing Reactivity and Site-Selectivity in Hydrogen Atom Transfer from Amino Acid C-H Bonds via Deprotonation.

A kinetic study on the reactions of the cumyloxyl radical (CumO) with N-Boc-protected amino acids in the presence of the strong organic base DBU has been carried out. COH deprotonation increases the electron density at the α-C-H bonds activating these bonds toward HAT to the electrophilic CumO strongly influencing the intramolecular selectivity. The implications of these results are discussed in the framework of HAT-based aliphatic C-H bond functionalization of amino acids and peptides.

Electronic and Torsional Effects on Hydrogen Atom Transfer from Aliphatic C-H Bonds: A Kinetic Evaluation via Reaction with the Cumyloxyl Radical.

A kinetic study on the hydrogen atom transfer (HAT) reactions from the aliphatic C-H bonds of a series of 1-Z-pentyl, 1-Z-propyl, and Z-cyclohexyl derivatives and of a series of N-alkylamides and N-alkylphthalimides to the electrophilic cumyloxyl radical (CumO) has been carried out. With 1-pentyl and 1-propyl derivatives, α-CH activation toward CumO is observed for Z = Ph, OH, NH, and NHAc, as evidenced by an increase in k as compared to the unsubstituted alkane substrate. A decrease in k has been instead measured for Z = OAc, NPhth, COMe, Cl, Br, and CN, indicative of α-CH deactivation with HAT that predominantly occurs from the most remote methylenic site.

Aerobic Oxidation of 4-Alkyl-N,N-dimethylbenzylamines Catalyzed by N-Hydroxyphthalimide: Protonation-Driven Control over Regioselectivity.

A change in regioselectivity has been observed in the hydrogen atom transfer (HAT) reactions from 4-alkyl-N,N-dimethylbenzylamines (alkyl = ethyl, isopropyl, and benzyl) to the phthalimide N-oxyl radical (PINO) by effect of protonation. This result can be rationalized on the basis of an acid-induced deactivation of the C-H bonds α to nitrogen toward HAT to PINO as evidenced by the 10-10-fold decrease in the HAT rate constants in acetonitrile following addition of 0.1 M HClO.