Monthly Archives: October 2023

Study of the Antioxidant, Antimicrobial, and Wound Healing Properties of Raw Hydrolyzed Extract from Nile Tilapia Skin (Oreochromis niloticus)

Posted on by
Study of the Antioxidant, Antimicrobial, and Wound Healing Properties of Raw Hydrolyzed Extract from Nile Tilapia Skin (Oreochromis niloticus)


Abstract

Oreochromis niloticus (Nile tilapia) skin is a by-product of Brazilian fish farming, rich in collagen. The present study aims to evaluate the wound healing, antioxidant, and antimicrobial potential of the raw hydrolyzed extract of Nile tilapia skin, as well as the identification of the main compounds. The in vitro activity was performed using antioxidant, antimicrobial and scratch wound healing assays. An in vivo experiment was performed to evaluate the wound healing potential. On days 1, 7, 14 and 21, the lesions were photographed to assess wound retraction and on the 7th, 14th and 21st days the skins were removed for histological evaluation and the blood of the animals was collected for glutamic oxaloacetic transaminase and glutamic pyruvic transaminase determination. The chemical study was carried out through liquid chromatography-tandem mass spectrometry and de novo sequencing of peptides. The in vitro assays showed a reduction of the gap area in 24 h, dose-dependent antimicrobial activity for both bacteria, and antioxidant activity. The chemical analysis highlighted the presence of active biopeptides. The histological evaluation showed that the raw hydrolyzed extract of Nile tilapia skin has a healing potential, and does not present toxicological effects; therefore, is promising for the treatment of wounds.

Cellular Mechanistic Considerations on Cytotoxic Mode of Action of Phosphino Ru(II) and Ir(III) Complexes

Posted on by
Cellular Mechanistic Considerations on Cytotoxic Mode of Action of Phosphino Ru(II) and Ir(III) Complexes

Our study proved that in the case of Ru(II) complexes the intense ROS generation is mainly responsible for the resulting cytotoxicity. The corresponding Ir(III) complexes trigger simultaneously at least three different cytotoxic pathways i. e., depletion of mitochondrial potential, activation of caspases-dependent apoptosis, and ROS-associated oxidation.


Abstract

Two piano-stool ruthenium(II) complexes Ru(η6-p-cymene)Cl2PPh2CH2OH (RuPOH) and Ru(η6-p-cymene)Cl2P(p-OCH3Ph)2CH2OH (RuMPOH) and two half-sandwich iridium(III) complexes Ir(η 5-Cp*)Cl2PPh2CH2OH (IrPOH) and Ir(η 5-Cp*)Cl2P(p-OCH3Ph)2CH2OH (IrMPOH) have been studied in terms of potential anticancer activity on previously selected cell line (human lung adenocarcinoma). Based on experimental results obtained in monoculture in vitro model mechanistic considerations on the possible cellular modes of action have been carried out. ICP-MS analysis revealed the higher cellular uptake for less hydrophobic Ir(III) complexes in comparison to the corresponding Ru(II) compounds. Cytometric analysis showed a predominance of apoptosis over the other types of cell death for all complexes. The apoptotic pathway was confirmed by a decrease in mitochondrial membrane potential and the activation of caspases-3/9 for both Ru(II) and Ir(III) complexes. It was concluded that in the case of Ru(II) complexes the intense ROS generation is mainly responsible for the resulting cytotoxicity. The corresponding Ir(III) complexes trigger simultaneously at least three different cytotoxic pathways i. e., depletion of mitochondrial potential, activation of caspases-dependent apoptosis, and ROS-associated oxidation. Thus, it can be assumed that the final accumulation of toxic effects over time via parallel activation of different pathways results in the highest cytotoxicity in vitro exhibited by Ir(III) complexes when compared with Ru(II) complexes.

Reversible Binding of Hydrogen and Styrene Coordination on a Manganese Phosphenium Complex

Posted on by
Reversible Binding of Hydrogen and Styrene Coordination on a Manganese Phosphenium Complex

Co-photolysis of two simple N-heterocyclic phosphenium complexes with H2 proceeds in one case under cooperative addition of H2 across the P=Mn double bond and in the other case via decarbonylation without participation of H2. The origin of this divergence and preliminary results on the passing on of the H2 molecule to styrene are discussed.


Abstract

The reactions of two complexes [(RNHP)Mn(CO)4] (RNHP=N-arylated N-heterocyclic phosphenium) with H2 at elevated pressure (≈4 bar) were studied by NMR spectroscopy. Irradiation with UV light initialized in one case (5 a, R=Dipp) the unselective formation of (RNHP-H)MnH(CO)4] (6 a) via cooperative addition of H2 across the Mn=P double bond. In the other case (5 b, R=Mes), addition of H2 was unobservable and the reaction proceeded via decarbonylation to a dimeric species [(RNHP)2Mn2(CO)7] (7 b) that was isolated and identified spectroscopically. Taking into account the outcome of further reaction studies under various conditions in the absence and presence of H2, both transformations can be explained in the context of a common mechanism involving decarbonylation to 7 a,b as the first step, and the different outcome is attributable to the fact that 7 b is unreactive towards both H2 and CO while 7 a is not. DFT studies relate this divergence to deviations in the molecular constitution and stability arising from a different level of steric congestion. Preliminary studies suggest further that 5 a/H2 as well as 6 a enable the photo-induced hydrogenation of styrene to ethyl benzene, even if the mechanism and possibly catalytic nature of this process remain yet unknown.

Reduced Graphene Oxide Modulated FeSe/C Anode Materials for High‐Stable and Long‐Life Potassium‐Ion Batteries

Posted on by
Reduced Graphene Oxide Modulated FeSe/C Anode Materials for High-Stable and Long-Life Potassium-Ion Batteries

The rGO layer on electrode exhibits robust adsorption energies towards EC, DEC, and K+-ions, regulating the EDL around electrode. The special behavior changes the SEI and markedly improves the reaction kinetics. Meanwhile, rGO with robust mechanical properties remains the integrity of SEI and FeSe/C@rGO electrode. Under these synergies, the anode exhibits excellent potassium storage properties.


Abstract

Reduced graphene oxide (rGO) has been demonstrated to effectively enhance the potassium storage performance of transition metal selenides due to its robust mechanical properties and high conductivity. However, the impact of rGO on the electrode-electrolyte interface, a crucial factor in the electrochemical performance of potassium-ion batteries (PIBs), requires further exploration. In this study, we synthesized a seamless architecture of rGO on FeSe/C nanocrystals (FeSe/C@rGO). Comparative analysis between FeSe/C and FeSe/C@rGO reveals that the rGO layer exhibits robust adsorption energies towards EC and DEC, inducing the formation of organic-rich solid-electrolyte interphase (SEI) without damage to the structural integrity. Furthermore, incorporating rGO triggers K+-ions into the double electrode layer (EDL), markedly improving the transport of K+-ions. As a PIB anode, FeSe/C@rGO exhibits a reversible capacity of 332 mAh g−1 at 200 mA g−1 after 300 cycles, along with excellent long-term cycling stability, showcasing an ultralow decay rate of only 0.086 % per cycle after 1900 cycles at 1000 mA g−1.

Cooperative Dinitrogen Activation: Identifying the Push‐Pull Effects of Transition Metals and Lewis Acids in Molecular Orbital Diagrams

Posted on by
Cooperative Dinitrogen Activation: Identifying the Push-Pull Effects of Transition Metals and Lewis Acids in Molecular Orbital Diagrams

The cooperative “push-pull” effects of ReI, Mo0, W0 complexes and borane Lewis acids on the dinitrogen bond are evaluated in molecular orbital diagrams: we extract electronic design principles in terms of orthogonal σ and π “push-pull” paths that may guide the design of complexes towards the desired thermal, electrochemical or photochemical reactivity of N2.


Abstract

The sustainable fixation of atmospheric N2 and its conversion into industrially relevant molecules is one of the major current challenges in chemistry. Besides nitrogen activation with transition metal complexes, a “push-pull” approach that fine-tunes electron density along the N−N bond has shown success recently. The “pushing” is performed by an electron rich entity such as a transition metal complex, and the “pulling” is achieved with an electron acceptor such as a Lewis acid. In this contribution, we explore the electronic structure implications of this approach using the complex trans-[ReICl(N2)(PMe2Ph)4] as a starting point. We show that borane Lewis acids exert a pull-effect of increasing strength with increased Lewis acidity via a π-pathway. Furthermore, the ligand trans to dinitrogen can weaken the dinitrogen bond via a σ-pathway. Binding a strong Lewis acid is found to have electronic structure effects potentially relevant for electrochemistry: dinitrogen-dominated molecular orbitals are shifted into advantageous energetic positions for redox activation of the dinitrogen bond. We show how these electronic structure design principles are rooted in cooperative effects of a transition metal complex and a Lewis acid, and that they can be exploited to tailor a complex towards the desired thermal, electrochemical or photochemical reactivity.

Benzothiadiazolyl‐pyridine and ‐2,2′‐bipyridine Ligands for Luminescent and Magnetic Complexes

Posted on by
Benzothiadiazolyl-pyridine and -2,2′-bipyridine Ligands for Luminescent and Magnetic Complexes

Luminescent zinc(II) and paramagnetic copper(II) and manganese(II) complexes have been prepared with unprecedented benzothiadiazolyl−pyridine and −2,2′-bipyridine ligands.


Abstract

Two new luminescent ligands, 4-(2-pyridine)-7-methyl-2,1,3-benzothiadiazole (L1) and 4-(2,2-bipyridine)-7-methyl-2,1,3-benzothiadiazole (L2), based on 2,1,3-benzothiadiazole and pyridine or bipyridine were obtained by Suzuki coupling reactions. DFT and TD-DFT type calculations have been performed on L1 and L2 in order to assign their experimental UV-visible and emission bands. Reaction of L1 and L2 with metal(II) chlorides (M=Zn, Mn, Cu) provided the neutral complexes of formulas [ZnL1Cl2] (1), [Zn(L1)2Cl2] (2), [ZnL2Cl2] (3), [MnL2Cl2] ⋅ 0,5CH2Cl2 (4) and [CuL2Cl2] ⋅ H2O (5) which have been structurally characterized. The Zn(II) ions in 1 and 2 are four-coordinate in somewhat distorted tetrahedral N2Cl2 surroundings with L1 adopting bidentate (1) and monodentate (2) coordination modes. Complexes 3–5 are isostructural and their metal atoms are five-coordinate in distorted square pyramidal environments with three nitrogen atoms from the tridentate L2 ligand and a chlorine building the basal plane and another chlorine atom occupying the apical position. The three Zn(II) complexes are strongly luminescent in solution and the solid state, while the cryomagnetic study of the paramagnetic compounds 4 and 5 in the temperature range 2.9–300 K shows a Curie-Weiss behaviour typical of small antiferromagnetic interactions which are mediated by weak intermolecular contacts.

Electrochemical Synthesis of Phenothiazinone as Fluorophore and Its Application in Bioimaging

Posted on by
Electrochemical Synthesis of Phenothiazinone as Fluorophore and Its Application in Bioimaging

Electrochemical synthesis of phenothiazinone via oxidative cyclocondensation of quinone and 2-aminothiophenol under mild condition is presented, along with its bio-application as fluorophore for lipid droplets imaging in living cells.


Abstract

Phenothiazinone is a promising yet underutilized fluorophore, possibly due to the lack of a general accessibility. This study reports a robust and scalable TEMPO-mediated electrochemical method to access a variety of phenothiazinones from 2-aminothiophenols and quinones. The electrosynthesis proceeds in a simple cell architecture under mild condition, and notably carbon–halogen bond in quinones remains compared to conventional methods, enabling orthogonal downstream functionalization. Mechanistic studies corroborate that TEMPO exerts a protective effect in avoiding product decomposition at the cathode. In particular, benzophenothiazinones show intriguing luminescence in both solid and solution state, and thus their photophysical properties are scrutinized in detail. Further bio-imaging of the lipid droplets in living cells highlights the considerable promise of benzophenothiazinones as fluorescent dye in the biomedical fields.

Photo/electrocatalytic Reduction of CO2 to C2+ Products on MOF‐Based Catalysts

Posted on by
Photo/electrocatalytic Reduction of CO2 to C2+ Products on MOF-Based Catalysts

Photo/electrocatalytic reduction of CO2 to C2+ products is one of the most promising approaches for simultaneously mitigating the greenhouse gases CO2 emission and producing value-added fuels. In this review, we present an overview of the latest advances of photo/electrocatalytic CO2 reduction to C2+ products with focus on the catalytic performance depending on rational design of desired MOF-based catalysts.


Abstract

Efficient conversion of CO2 to valuable fuels is a desired approach to reduce global warming effect and remit sustained fossil fuel demand. Metal–organic frameworks (MOFs), a class of crystalline porous materials with unique features, have been widely studied for potential applications in varied fields. Recently, photo/electrocatalytic reduction of CO2 to two or more carbons (C2+) products has attracted extensive attention because of their higher market values than one carbon (C1). However, the major products of CO2 reduction currently are carbon monoxide, formate, or methane, which are all typical C1 products. Generally, for photocatalytic reduction of CO2 system, relatively low efficiency of electron transfer with inadequate capability results sluggish kinetics of C−C coupling. And for electrocatalysis, high current densities curtail the stability, which limits selectivity towards C2+ products. In this review, we provide very latest reports that have make some breakthroughs to overcome the above difficulties in photo/electrocatalytic reduction of CO2 to C2+ products using MOF-based materials. Special emphases are given on design strategies of synthetic MOF-based catalysts and the mechanisms of catalytic CO2 to C2+ products. The challenges and prospects of photo/electrocatalytic reduction of CO2 to C2+ products associated with MOF-based materials are also discussed.

Preparation of Palladium‐Doped Nickel Phosphide Nanoparticles as Efficient Electrocatalysts for Alkaline Hydrogen Evolution Reaction

Posted on by
Preparation of Palladium-Doped Nickel Phosphide Nanoparticles as Efficient Electrocatalysts for Alkaline Hydrogen Evolution Reaction

Colloidal, atomically dispersed Pd-doped Ni2P nanoparticles were prepared. The Pd dopant regulates the electronic structure of Ni2P NPs and provides an efficient active site for hydrogen production, which exhibits efficient water splitting.


Abstract

Hydrogen production through electrochemical water splitting has gained significant attention owing to its environmental benefits over traditional methods. However, designing an efficient electrocatalyst for the hydrogen evolution reaction (HER) in an alkaline electrolyte remains a significant challenge. In this study, colloidal Pd-doped Ni2P nanoparticles were prepared via a thermal decomposition-based strategy and used as electrocatalysts for the hydrogen evolution reaction. The Pd dopant is atomically dispersed within the Ni2P nanoparticles, regulating their electronic structure and providing an efficient active site for hydrogen production. The Pd-doped Ni2P nanoparticles exhibited excellent electrocatalytic performance with an overpotential of 77 mV at 10 mA cm−2 in an alkaline electrolyte and a small Tafel slope of 46 mV dec−1.

A Hydrophobic Deep Eutectic Solvent for Nuclear Fuel Cycle: Extraction of Actinides and Dissolution of Uranium Oxide

Posted on by
A Hydrophobic Deep Eutectic Solvent for Nuclear Fuel Cycle: Extraction of Actinides and Dissolution of Uranium Oxide

A hydrophobic DES having low density and viscosity based on Thenoyl trifluroacetone (HTTA) and Trioctyl phosphine oxide (TOPO) was shown to extract and partition actinides and lanthanides and used as a medium for dissolution of uranium oxide.


Abstract

Hydrophobic Deep Eutectic Solvents (DESs) have been attracting attention for metal ion extraction in solvent extraction process due to their favorable properties. A Trioctyl phosphine oxide (TOPO) and Thenoyl trifluoroacetone (HTTA) based hydrophobic DES was synthesized and characterized by FTIR and NMR spectroscopy. Actinide ions ( UO2 2+, Pu4+ and Am3+) and Eu3+ ion extraction was carried out using the DES which shows that it extracts these metal ions from aqueous nitric acid medium depending upon the molarity of nitric acid. At higher molarity of nitric acid (>5 M) the extraction becomes insignificant only for trivalent metal ions and open up the possibility to selectively strip trivalent metal ions from tetravalent and hexavalent ions. This DES was also used for dissolution of uranium oxide (UO3). The dissolution kinetics was studied and it was shown that oxide was dissolved within an hour at 80 °C. The maximum solubility of UO3 in DES was measured and found to be 130±5 mg/mL which is one of the highest reported solubility of UO3 in ILs and DES. The species of uranium which is formed in situ in DES was ascertained to be UO2(TTA)2.TOPO after dissolution of UO3 as supported by FTIR and NMR (1H and 31P) investigations.