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1.
Inorg Chem ; 63(27): 12681-12689, 2024 Jul 08.
Artigo em Inglês | MEDLINE | ID: mdl-38922608

RESUMO

The oxygen reduction reaction (ORR) plays a vital role in many next-generation electrochemical energy conversion and storage devices, motivating the search for low-cost ORR electrocatalysts possessing high activity and excellent durability. In this work, we demonstrate that iron-cobalt phosphide (FeCoP) nanoparticles encapsulated in a N-doped carbon framework (FeCoP@NC) represent a very promising catalyst for the ORR in alkaline media. The core-shell structured FeCoP@NC catalyst offered outstanding ORR activity with a half-wave potential (E1/2) of 0.86 V vs reversible hydrogen electrode (RHE) and excellent stability in a 0.1 M KOH electrolyte, outperforming commercial Pt/C and many recently reported noble-metal-free ORR electrocatalysts. The superiority of FeCoP@NC as an ORR electrocatalyst relative to Pt/C was further verified in prototype zinc-air batteries (ZABs), with the aqueous and flexible ZABs prepared using FeCoP@NC offering excellent stability, impressive open circuit voltages (1.56 and 1.44 V, respectively), and high maximum power densities (183.5 and 69.7 mW cm-2, respectively). Density functional theory calculations revealed that encapsulating FeCoP nanoparticles in N-doped carbon shells resulted in favorable electron penetration effects, which synergistically regulated the adsorption/desorption of ORR intermediates for optimal ORR performance while also boosting the electronic conductivity. Our findings offer valuable new insights for rational design of transition metal phosphide-based catalysts for the ORR and other electrochemical applications.

2.
J Chromatogr A ; 1726: 464963, 2024 Jul 05.
Artigo em Inglês | MEDLINE | ID: mdl-38723493

RESUMO

The monitoring of organic compounds in aquatic matrices poses challenges due to its complexity and time-intensive nature. To address these challenges, we introduce a novel approach utilizing a dual-channel mono (1D) and comprehensive two-dimensional (2D) gas chromatography coupled with time-of-flight mass spectrometry (GC × GC-TOFMS) system, integrated with a robotic pretreatment platform, for online monitoring of both volatile organic compounds (VOCs) and semivolatile organic compounds (SVOCs) in water matrices. Employing the robotic platform, we establish a suite of online liquid-liquid extraction (LLE) pretreatment processes for water samples, marking the first instance of such procedures. Leveraging the automatic headspace (HS) module, dual robotic preparations of HS and LLE are sequentially executed to extract VOCs and SVOCs from water matrices. The GC × GC-TOFMS system is distinguished by its dual-channel analytical column configuration, facilitating sequential analysis of VOCs in GC-TOFMS mode and SVOCs in GC × GC-TOFMS mode. Quantitative detection of 55 target VOCs and 104 SVOCs is achieved in a water sample using the instrument system. Our method demonstrates excellent correlation coefficients ranging from 0.990 to 1.000, method detection limits ranging from 0.08 to 4.78 µg L-1, relative standard deviations below 19.3 %, and recovery rates ranging from 50.0 % to 124.0 %. To validate the online monitoring capabilities of our system, we assess target SVOCs at three different concentration levels over a 3-day period. Most compounds exhibit recovery rates ranging from 70.0 % to 130.0 %. Furthermore, we apply our method to analyze a real water sample, successfully identifying over 100 target and nontarget VOCs/SVOCs, including alcohols, aldehydes, ketones, acids, esters, and phenols. These results highlight the efficacy of the proposed analysis system, capable of conducting two distinct analyses in automatic sequence, thereby enhancing the efficiency and accuracy of organic compound analysis in water matrices.


Assuntos
Cromatografia Gasosa-Espectrometria de Massas , Extração Líquido-Líquido , Robótica , Compostos Orgânicos Voláteis , Compostos Orgânicos Voláteis/análise , Compostos Orgânicos Voláteis/isolamento & purificação , Cromatografia Gasosa-Espectrometria de Massas/métodos , Extração Líquido-Líquido/métodos , Poluentes Químicos da Água/análise , Poluentes Químicos da Água/isolamento & purificação , Limite de Detecção
3.
Food Chem ; 446: 138880, 2024 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-38432140

RESUMO

Biodegradable food packaging films with good antimicrobial properties are highly sought after for prolonging the shelf-life of fruits and vegetables whilst minimizing waste streams originating from the food sector. In this work, a series of PBAT/PLA food packaging films containing sodium dehydroacetate-loaded diatomite (SD/D) as an antimicrobial agent were fabricated. Structural analyses showed that the sodium dehydroacetate was incorporated into the pores of the diatomite. A uniform dispersion of SD/D in the composite films effectively enhanced water and gas permeability, whilst also giving the films good mechanical properties. The slow release of SD endowed the composite films with long-acting antibacterial ability (>90 % bacteriostasis rate for E. coli and >85 % bacteriostasis rate for S. aureus). The composite films were able to effectively maintain the quality of banana fruits during storage at room temperature, encouraging their use in food applications where non-biodegradable petrochemical-derived packaging films have traditionally been used.


Assuntos
Anti-Infecciosos , Terra de Diatomáceas , Embalagem de Alimentos , Pironas , Antibacterianos/farmacologia , Antibacterianos/química , Água , Escherichia coli , Staphylococcus aureus , Poliésteres/química , Anti-Infecciosos/farmacologia
4.
Nat Commun ; 15(1): 789, 2024 Jan 26.
Artigo em Inglês | MEDLINE | ID: mdl-38278813

RESUMO

The selective oxidative dehydrogenation of ethane (ODHE) is attracting increasing attention as a method for ethylene production. Typically, thermocatalysts operating at high temperatures are needed for C-H activation in ethane. In this study, we describe a low temperature ( < 140 °C) photocatalytic route for ODHE, using O2 as the oxidant. A photocatalyst containing PdZn intermetallic nanoparticles supported on ZnO is prepared, affording an ethylene production rate of 46.4 mmol g-1 h-1 with 92.6% ethylene selectivity under 365 nm irradiation. When we employ a simulated shale gas feed, the photocatalytic ODHE system achieves nearly 20% ethane conversion while maintaining an ethylene selectivity of about 87%. The robust interface between the PdZn intermetallic nanoparticles and ZnO support plays a crucial role in ethane activation through a photo-assisted Mars-van Krevelen mechanism, followed by a rapid lattice oxygen replenishment to complete the reaction cycle. Our findings demonstrate that photocatalytic ODHE is a promising method for alkane-to-alkene conversions under mild conditions.

5.
Mikrochim Acta ; 190(10): 383, 2023 09 12.
Artigo em Inglês | MEDLINE | ID: mdl-37697171

RESUMO

Covalent organic framework-coated magnetite particles (Fe3O4@COF) were synthesized and applied as the adsorbent to the selective capture of phthalate esters (PAEs) in liquid foods. Combined with the magnetic solid-phase extraction (MSPE) technology, a gas chromatography-tandem mass spectrometry (GC-MS/MS) method was employed for the separation and quantification of PAEs. Following optimization of the magnetic extraction and elution parameters, the developed analytical method offered a satisfactory linear range (0.1-5 µg L-1) with determination coefficients ranging from 0.9934 to 0.9975 for the five different PAEs studied. The limits of detection (LOD) were in the range 1.9-12.8 ng L-1. The recoveries ranged from 70.0 to 119.8% with a relative standard deviation (RSD) less than 9.7%. Density functional theory (DFT) calculations established that the dominant adsorption mechanism used by the COF to bind PAEs involved π-π stacking interactions. Results encourage the wider use of COF-based adsorbents and MSPE methods in the analytical determination of PAEs in foods.


Assuntos
Estruturas Metalorgânicas , Espectrometria de Massas em Tandem , Cromatografia Gasosa-Espectrometria de Massas , Extração em Fase Sólida , Fenômenos Magnéticos , Ésteres
6.
Food Chem ; 429: 136874, 2023 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-37454616

RESUMO

This study addresses the limitations of konjac glucomannan (KGM) films in mechanical properties, hydrophobicity and antibacterial activities. For the first time, a zein-pectin nanoparticle-stabilized corn germ oil-oregano essential oil Pickering emulsion (ZPCEO) was incorporated into KGM, with the resulting film being further ionically crosslinked with Ca2+, Cu2+ or Fe3+. FTIR, SEM and EDS results showed that the metal ions were crosslinked with the hydroxyl and carbonyl groups of polysaccharides and uniformly distributed throughout the films (degree of crosslinking: Fe3+ > Cu2+ > Ca2+). Compared with pure KGM films, the ionic crosslinked ZPCEO/KGM (IL-ZPCEO/KGM) films have superior water resistance mechanical properties, and exhibit unique UV-blocking properties, antioxidant and antibacterial activities. The ZPCEO/KGM-Fe3+ film offered the best all-round properties, including the highest tensile strength, water resistance, UV-blocking capacity, and antimicrobial activity. Thus, ionic crosslinking of ZPCEO/KGM films can be applied to the preparation of food packaging for use in high humidity environments.


Assuntos
Nanopartículas , Origanum , Zeína , Embalagem de Alimentos , Zea mays , Pectinas , Emulsões , Água , Mananas , Antibacterianos/farmacologia
7.
Adv Mater ; 35(42): e2303818, 2023 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-37433306

RESUMO

Electrochemical acetylene reduction (EAR) is a promising strategy for removing acetylene from ethylene-rich gas streams. However, suppressing the undesirable hydrogen evolution is vital for practical applications in acetylene-insufficient conditions. Herein, Cu single atoms are immobilized on anatase TiO2 nanoplates (Cu-SA/TiO2 ) for electrochemical acetylene reduction, achieving an ethylene selectivity of ≈97% with a 5 vol% acetylene gas feed (Ar balance). At the optimal Cu-single-atom loading, Cu-SA/TiO2 is able to effectively suppress HER and ethylene over-hydrogenation even when using dilute acetylene (0.5 vol%) or ethylene-rich gas feeds, delivering a 99.8% acetylene conversion, providing a turnover frequency of 8.9 × 10-2  s-1 , which is superior to other EAR catalysts reported to date. Theoretical calculations show that the Cu single atoms and the TiO2 support acted cooperatively to promote charge transfer to adsorbed acetylene molecules, whilst also inhibiting hydrogen generation in alkali environments, thus allowing selective ethylene production with negligible hydrogen evolution at low acetylene concentrations.

8.
ACS Appl Mater Interfaces ; 15(26): 31584-31594, 2023 Jul 05.
Artigo em Inglês | MEDLINE | ID: mdl-37339248

RESUMO

Metal-oxide interfaces on Cu-based catalysts play very important roles in the low-temperature water-gas shift reaction (LT-WGSR). However, developing catalysts with abundant, active, and robust Cu-metal oxide interfaces under LT-WGSR conditions remains challenging. Herein, we report the successful development of an inverse copper-ceria catalyst (Cu@CeO2), which exhibited very high efficiency for the LT-WGSR. At a reaction temperature of 250 °C, the LT-WGSR activity of the Cu@CeO2 catalyst was about three times higher than that of a pristine Cu catalyst without CeO2. Comprehensive quasi-in situ structural characterizations indicated that the Cu@CeO2 catalyst was rich in CeO2/Cu2O/Cu tandem interfaces. Reaction kinetics studies and density functional theory (DFT) calculations revealed that the Cu+/Cu0 interfaces were the active sites for the LT-WGSR, while adjacent CeO2 nanoparticles play a key role in activating H2O and stabilizing the Cu+/Cu0 interfaces. Our study highlights the role of the CeO2/Cu2O/Cu tandem interface in regulating catalyst activity and stability, thus contributing to the development of improved Cu-based catalysts for the LT-WGSR.

9.
Food Chem ; 423: 136319, 2023 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-37187007

RESUMO

Organophosphorus pesticide (OP) residues pose a serious threat to human health, motivating the search for novel adsorbents and detection methods. Herein, defective copper-based metal organic frameworks (Cu-MOFs) were synthesized by the reaction of Cu2+ ions and 1,3,5-benzenetricarboxylate linkers in the presence of acetic acid. As the amount of acetic acid increased, the crystallization kinetics and morphology of the Cu-MOFs changed, leading to mesoporous Cu-MOFs with many large surface pores (defects). Adsorption studies of OPs revealed the defective Cu-MOFs showed faster pesticide adsorption kinetics and higher pesticide adsorption capacities. Density functional theory calculations showed that pesticide adsorption in the Cu-MOFs was mainly electrostatic. A dispersive solid phase extraction method was developed based on a defective Cu-MOF-6 for rapidly extracting pesticides from food samples. The method allowed pesticide detection over a wide linear concentration range, low limits of detection (0.0067-0.0164 µg L-1) and good recoveries in pesticide-spiked samples (81.03-109.55%).


Assuntos
Estruturas Metalorgânicas , Resíduos de Praguicidas , Praguicidas , Humanos , Cobre/química , Praguicidas/análise , Compostos Organofosforados , Estruturas Metalorgânicas/química , Adsorção
10.
Small ; 19(24): e2300373, 2023 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-36919312

RESUMO

FeNC catalysts demonstrate remarkable activity and stability for the oxygen reduction reaction (ORR) in polymer electrolyte membrane fuel cells and Zn-air batteries (ZABs). The local coordination of Fe single atoms in FeNC catalysts strongly impacts ORR activity. Herein, FeNC catalysts containing Fe single atoms sites with FeN3 , FeN4 , and FeN5 coordinations are synthesized by carbonization of Fe-rich polypyrrole precursors. The FeN5 sites possess a higher Fe oxidation state (+2.62) than the FeN3 (+2.23) and FeN4 (+2.47) sites, and higher ORR activity. Density functional theory calculations verify that the FeN5 coordination optimizes the adsorption and desorption of ORR intermediates, dramatically lowering the energy barrier for OH- desorption in the rate-limiting ORR step. A primary ZAB constructed using the FeNC catalyst with FeN5 sites demonstrates state-of-the-art performance (an open circuit potential of 1.629 V, power density of 159 mW cm-2 ). Results confirm an intimate structure-activity relationship between Fe coordination, Fe oxidation state, and ORR activity in FeNC catalysts.

11.
Metabolites ; 13(2)2023 Feb 03.
Artigo em Inglês | MEDLINE | ID: mdl-36837850

RESUMO

Quercetin is a flavonol found in edible plants and possesses a significant anticancer activity. This study explored the mechanism by which quercetin prevented liver cancer via inducing apoptosis in HepG2 cells. Quercetin induced cell proliferation and apoptosis through inhibiting YY1 and facilitating p53 expression and subsequently increasing the Bax/Bcl-2 ratio. The results revealed that YY1 knockdown promoted apoptosis, whilst YY1 overexpression suppressed apoptosis via direct physical interaction between YY1 and p53 to regulate the p53 signaling pathway. Molecular docking using native and mutant YY1 proteins showed that quercetin could interact directly with YY1, and the binding of quercetin to YY1 significantly decreased the docking energy of YY1 with p53 protein. The interactions between quercetin and YY1 protein included direct binding and non-bonded indirect interactions, as confirmed by cellular thermal shift assay, UV-Vis absorption spectroscopy, fluorescence spectroscopy and circular dichroism spectroscopy. It was likely that quercetin directly bound to YY1 protein to compete with p53 for the binding sites of YY1 to disrupt the YY1-p53 interaction, thereby promoting p53 activation. This study provides insights into the mechanism underlying quercetin's anticancer action and supports the development of quercetin as an anticancer therapeutic agent.

12.
Angew Chem Int Ed Engl ; 62(13): e202219299, 2023 Mar 20.
Artigo em Inglês | MEDLINE | ID: mdl-36734471

RESUMO

The activation of water molecules in thermal catalysis typically requires high temperatures, representing an obstacle to catalyst development for the low-temperature water-gas shift reaction (WGSR). Plasmonic photocatalysis allows activation of water at low temperatures through the generation of light-induced hot electrons. Herein, we report a layered double hydroxide-derived copper catalyst (LD-Cu) with outstanding performance for the low-temperature photo-driven WGSR. LD-Cu offered a lower activation energy for WGSR to H2 under UV/Vis irradiation (1.4 W cm-2 ) compared to under dark conditions. Detailed experimental studies revealed that highly dispersed Cu nanoparticles created an abundance of hot electrons during light absorption, which promoted *H2 O dissociation and *H combination via a carboxyl pathway, leading to the efficient production of H2 . Results demonstrate the benefits of exploiting plasmonic phenomena in the development of photo-driven low-temperature WGSR catalysts.

13.
Food Chem ; 410: 135434, 2023 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-36641911

RESUMO

Chloramphenicol (CAP) is a widely used antibiotic for the treatment of sick animals owing to its potent action and low cost. However, the accumulation of CAP in the human body can cause irreversible aplastic anemia and hematopoietic toxicity. Accordingly, development of various analytical techniques for the rapid detection of CAP in animal products and the related processed foods is necessary. Among these analytical techniques, electrochemical and optical sensors offer many advantages for CAP detection, including high sensitivity, simple operation and fast analysis speed. In this review, we summarize recent application of carbon nanomaterials, metal nanoparticles, metal oxide nanoparticles and metal organic framework in the development of electrochemical and optical sensors for CAP detection (2010-2022). Based on the advantages and disadvantages of nanomaterials, electrochemical and optical sensors are summarized in this review. The preparation and synthesis of electrochemical and optical sensors and nanomaterials in the field of rapid detection are prospected.


Assuntos
Nanopartículas Metálicas , Nanoestruturas , Humanos , Animais , Cloranfenicol/análise , Antibacterianos/análise , Alimentos , Técnicas Eletroquímicas/métodos
14.
Crit Rev Food Sci Nutr ; 63(19): 3386-3419, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-34637646

RESUMO

The numerous health benefits of pectins justify their inclusion in human diets and biomedical products. This review provides an overview of pectin extraction and modification methods, their physico-chemical characteristics, health-promoting properties, and pharmaceutical/biomedical applications. Pectins, as readily available and versatile biomolecules, can be tailored to possess specific functionalities for food, pharmaceutical and biomedical applications, through judicious selection of appropriate extraction and modification technologies/processes based on green chemistry principles. Pectin's structural and physicochemical characteristics dictate their effects on digestion and bioavailability of nutrients, as well as health-promoting properties including anticancer, immunomodulatory, anti-inflammatory, intestinal microflora-regulating, immune barrier-strengthening, hypercholesterolemia-/arteriosclerosis-preventing, anti-diabetic, anti-obesity, antitussive, analgesic, anticoagulant, and wound healing effects. HG, RG-I, RG-II, molecular weight, side chain pattern, and degrees of methylation, acetylation, amidation and branching are critical structural elements responsible for optimizing these health benefits. The physicochemical characteristics, health functionalities, biocompatibility and biodegradability of pectins enable the construction of pectin-based composites with distinct properties for targeted applications in bioactive/drug delivery, edible films/coatings, nano-/micro-encapsulation, wound dressings and biological tissue engineering. Achieving beneficial synergies among the green extraction and modification processes during pectin production, and between pectin and other composite components in biomedical products, should be key foci for future research.


Assuntos
Alimentos , Pectinas , Humanos , Estrutura Molecular , Peso Molecular , Preparações Farmacêuticas
15.
J Pept Sci ; 28(10): e3413, 2022 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-35445486

RESUMO

Cheap artificial light harvesting systems, which competently harvest solar energy and promote efficient energy transfer, are highly sought after in the renewable sector. We report the synthesis of self-assembled peptide-porphyrin fibers (SJ 6) fabricated with iron(III) oxide (Fe3 O4 ) nanoparticles as feasible electron acceptors. Charge-complementarity between the negatively charged peptide (20E) and the protonated Zn-tetraphenyl porphyrin (ZnTPyP) led to an ordered assembly of the ZnTPyP molecules, enabling efficient light harvesting. X-ray diffraction data indicates a more ordered structure in SJ 6 compared to 20E and ZnTPyP. The incorporation of Fe3 O4 nanoparticles into SJ 6 showed significant fluorescence quenching, indicating efficient electron flow from the donor to the acceptor. The SJ 6-nFe3 O4 system performed the light reaction of photosynthesis as confirmed by the reduction of 1 mM NAD+ to 0.180 mM NADH upon exposure to visible light (Xe lamp λ > 420 nm) for 1 h. The photochemical regeneration of NADH using the SJ 6-nFe3 O4 system was coupled to glutamate dehydrogenase-catalyzed conversion of α-ketoglutarate to L-glutamate. These results confirm the successful synthesis of an artificial light harvesting peptide-porphyrin system with Fe3 O4 nanoparticles as promising low-cost electron separators.


Assuntos
Nanopartículas Metálicas , Nanofibras , Porfirinas , Compostos Férricos , Luz , NAD/química , Óxidos , Peptídeos , Porfirinas/química
16.
Food Chem ; 387: 132918, 2022 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-35417842

RESUMO

Novel γ-[Glu](n≥1)-Gln-Ca chelates were prepared by using γ-[Glu](n≥1)-Gln (mixture peptides containg γ-Glu-Gln, γ-Glu-Glu-Gln, γ-Glu-Glu-Glu-Gln, γ-Glu-Glu-Glu-Glu-Gln, γ-Glu-Glu-Glu-Glu-Glu-Gln) which were synthesized by glutaminase. Based on single factor and orthogonal array experiments, the optimal calcium-chelation conditions were as follows: 30 min chelation at 70 °C; peptide concentration, 0.15 g/mL; mixture peptides-to-calcium mass ratio, 25:1. The particle size of chelates was 743.6 ± 64.2 nm and the chelates appeared stable neutral molecular entities with 91.33% of chelation rate and 35.2 mg/g of calcium, also with higher thermostability. Chelated calcium ions might be surrounded by coordination bonds linking to two or more connecting points: oxygen atoms (carboxyl oxygen, hydroxyl oxygen and oxygen of peptide bonds) and nitrogen atoms (amino nitrogen). The chelates could be used for food/nutraceutical applications, as no toxicity at 0.125-10 mg/mL and enhanced efficiency in calcium release (releasing percentage over 85% at pH 8.0), transport and uptake compared with CaCl2 were detected in Caco-2 cells.


Assuntos
Cálcio , Peptídeos , Disponibilidade Biológica , Células CACO-2 , Cálcio da Dieta , Humanos , Oxigênio , Peptídeos/metabolismo
17.
Chemosphere ; 288(Pt 1): 132509, 2022 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-34627811

RESUMO

Herein, polypyrrole/titanium oxide/reduced graphene oxide (PTi/r-GO) electrodes were prepared and successfully applied for the photoelectrocatalytic (PEC) degradation of methyl orange (MO) under visible light. Polypyrrole-TiO2 composites rich in p-n heterojunctions were first prepared, then modified with r-GO to improve the electrical conductivity and facilitate charge separation under visible light irradiation. The obtained PTi/r-GO composites were then deposited onto a titanium mesh, which served as the working electrode in PEC experiments. A MO removal efficiency of 93% was achieved in 50 min using PTi/r-GO electrode under PEC conditions (Xe lamp, λ > 420 nm, bias of 0.6 V, 0.1 M Na2SO4 electrolyte), which was far higher than MO removal efficiencies under electrocatalytic oxidation (22%) or photocatalytic oxidation (47%) conditions. This confirmed that excellent activity of the PTi/r-GO electrode under PEC conditions was due to a combination of electrochemical and photocatalytic oxidation processes (involving •OH and •O2- generation). Further, PTi/r-GO was very stable under the applied PEC conditions, with the MO removal efficiency remaining >90% after five cycles. PEC degradation pathways for MO on PTi/r-GO were explored, with a number of key intermediates in the MO mineralization process identified. Results demonstrate that PEC electrodes combining p-type polypyrrole, n-type TiO2 and rGO are very effective in the treatment of hazardous organic compounds in wastewater.


Assuntos
Polímeros , Titânio , Catálise , Corantes , Eletrodos , Grafite , Luz , Pirróis
18.
ACS Appl Mater Interfaces ; 13(50): 59649-59661, 2021 Dec 22.
Artigo em Inglês | MEDLINE | ID: mdl-34894645

RESUMO

Recent advances in the synthesis of multifunctional nanomaterials create new opportunities for the rational design of multimodal chemodynamic therapy (CDT) agents. Precisely tailoring the nanostructure and composition of CDT nanoagents for maximum efficacy remains a challenge. Herein, we report the successful synthesis of nanocarbon framework-supported ultrafine Mo2C@MoOx nanoclusters (C/Mo2C@MoOx) via a pyrolysis of a Mo/ZIF-8 MOF precursor at 900 °C followed by mild surface oxidation. The developed C/Mo2C@MoOx composite demonstrated outstanding performance in photothermal-enhanced tumor-specific tandem catalysis therapy. Specifically, C/Mo2C@MoOx efficiently catalyzed the conversion of endogenous H2O2 to cytotoxic 1O2 via a Russell mechanism, while also converting the O2 byproduct to cytotoxic ·O2- via an oxidase-like mechanism. A high dispersion of active Mo5+ sites in the exposed MoOx shell enhanced the reactive oxygen species (ROS)-generating efficiency of C/Mo2C@MoOx. Moreover, the Mo2C core in the ultrafine Mo2C@MoOx nanoclusters allowed NIR-II (1064 nm)-driven photothermal heating, which significantly boosted the CDT process through photothermal effects. Additionally, the CDT process relied on a redox cycle involving Mo5+/Mo6+ species, which could be sustained by glutathione (GSH) consumption. Given these advantages, C/Mo2C@MoOx demonstrated remarkable synergistic therapeutic efficacy for cancer treatment (both in vitro and in vivo) through tumor microenvironment-stimulated generation of multiple ROS and NIR-II photothermal activity.


Assuntos
Materiais Biocompatíveis/farmacologia , Peróxido de Hidrogênio/farmacologia , Terapia Fototérmica , Materiais Biocompatíveis/química , Carbono/química , Catálise , Sobrevivência Celular/efeitos dos fármacos , Ensaios de Seleção de Medicamentos Antitumorais , Células HeLa , Humanos , Peróxido de Hidrogênio/química , Teste de Materiais , Molibdênio/química , Nanoestruturas/química , Óxidos/química , Tamanho da Partícula
19.
Adv Mater ; 33(51): e2106621, 2021 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-34599784

RESUMO

Uranium extraction from seawater provides an opportunity for sustainable fuel supply to nuclear power plants. Herein, an adsorption-electrocatalysis strategy is demonstrated for efficient uranium extraction from seawater using a functionalized iron-nitrogen-carbon (Fe-Nx -C-R) catalyst, comprising N-doped carbon capsules supporting FeNx single-atom sites and surface chelating amidoxime groups (R). The amidoxime groups bring hydrophilicity to the adsorbent and offer surface-specific binding sites for UO2 2+ capture. The site-isolated FeNx centres reduce adsorbed UO2 2+ to UO2 + . Subsequently, through electrochemical reduction of the FeNx sites, unstable U(V) ions are reoxidized to U(VI) in the presence of Na+ resulting in the generation of solid Na2 O(UO3 ·H2 O)x , which can easily be collected. Fe-Nx -C-R reduced the uranium concentration in seawater from ≈3.5 ppb to below 0.5 ppb with a calculated capacity of ≈1.2 mg g-1 within 24 h. To the best of the knowledge, the developed system is the first to use the adsorption of uranyl ions and electrodeposition of solid Na2 O(UO3 .H2 O)x for the extraction of uranium from seawater. The important discoveries guide technology development for the efficient extraction of uranium from seawater.

20.
Front Nutr ; 8: 748031, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34631774

RESUMO

Origanum majorana L. is an aromatic herb that has been grown in several Mediterranean countries since ancient times, but became popular during the Middle Ages as a medicinal plant and seasoning ingredient. O. majorana has many pharmacological effects, but its immunoreactive components and mechanisms are still unclear. In this study, four compounds were isolated and identified from O. majorana by a spectral analysis, including 1H and 13C-NMR. They were 1H-indole-2-carboxylic acid (1), (+)-laricresol (2), (+)-isolaricresol (3), and procumboside B (4, pB), which were isolated for the first time in O. majorana. The immunomodulatory effects of the four compounds were screened, and pB had good immunomodulatory activity on RAW 264.7 cells. The immunomodulatory mechanism of pB was proved, in which pB could increase the secretion of nitric oxide (NO), interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), and reactive oxygen species (ROS) and simultaneously upregulate the expression of CD80 and CD86 on the cell surface. These results suggested that the mechanism of pB may be related to the activation of nuclear factor-kappaB (NF-κB) and mitogen-activated protein kinases (MAPKs)-signaling pathways. O. majorana is rich in nutrients and is commonly used in diets, so it can be used as a nutritional supplement with immunomodulatory effects.

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