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1.
Nanotechnology ; 2021 Feb 04.
Artigo em Inglês | MEDLINE | ID: mdl-33540385

RESUMO

The design of high-efficient and stable electrocatalysts for oxygen reduction reaction (ORR) is still a great challenge. Herein, we prepared Co,N-codoped carbon nanocomposites (Co@NC-ZM) with entangled carbon nanotubes. The large BET surface area (604.7 m2 g-1), rich mesoporous feature, Co,N doping and synergetic effect between various species of Co@NC-ZM can expose more active sites and facilitate the conductivity and mass transport. Benefiting from above unique superiorities, Co@NC-ZM performs excellent ORR performance with the more positive onset potential (0.96 V) and half-wave potential (0.83 V) than those of the commercial Pt/C (0.96 and 0.81 V, correspondingly). This work provides a new strategy for further exploring efficient non-precious metal-based catalysts for ORR.

2.
Nanoscale ; 2021 Jan 25.
Artigo em Inglês | MEDLINE | ID: mdl-33491021

RESUMO

The development of bifunctional catalysts with a delicate structure, high efficiency, and good durability for the oxygen evolution reaction (ORR) and oxygen evolution reaction (OER) is crucial to renewable Zn-air batteries. In this work, Co0.7Fe0.3 alloy nanoparticles (NPs) confined in N-doped carbon with a yolk-shell structure in multi-beaded fibers were prepared as a bifunctional electrocatalyst. The confinement structure was composed of an N-doped graphitized carbon shell and a core formed by numerous Co0.7Fe0.3 NPs, and was evenly threaded into a one-dimensional fiber. Moreover, this distinctive hierarchical structure featured abundant mesopores, a high BET surface area of 743.8 m2 g-1, good electronic conductivity, and uniformly distributed Co0.7Fe0.3/Co(Fe)-Nx coupling active sites. Therefore, the experimentally optimized Co0.7Fe0.3@NC2:1-800 showed excellent OER performance (overpotential reached 314 mV at 10 mA cm-2) that far exceeded RuO2 (353 mV), and good ORR catalytic performance (half-wave potential of 0.827 V) comparable to Pt/C (0.818 V). Impressively, the Co0.7Fe0.3@NC2:1-800 Zn-air battery delivered a higher open circuit voltage of 1.449 V, large power density of 85.7 mW cm-2, and outstanding charge-discharge cycling stability compared with the commercial RuO2 + 20 wt% Pt/C catalyst. This work provides new ideas for the structural design of electrocatalysts and energy conversion systems.

4.
Front Chem ; 8: 718, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32974282

RESUMO

The research in endogenous biomolecules from a single cell has grown rapidly in recent years since it is critical for dissecting and scrutinizing the complexity of heterogeneous tissues, especially under pathological conditions, and it is also of key importance to understand the biological processes and cellular responses to various perturbations without the limitation of population averaging. Although conventional techniques, such as micromanipulation or cell sorting methods, are already used along with subsequent molecular examinations, it remains a big challenge to develop new approaches to manipulate and directly extract small quantities of cytosol from single living cells. In this sense, nanostructure or nanomaterial may play a critical role in overcoming these challenges in cellular manipulation and extraction of very small quantities of cells, and provide a powerful alternative to conventional techniques. Since the nanostructures or nanomaterial could build channels between intracellular and extracellular components across cell membrane, through which cytosol could be pumped out and transferred to downstream analyses. In this review, we will first brief the traditional methods for single cell analyses, and then shift our focus to some most promising methods for single-cell sampling with nanostructures, such as glass nanopipette, nanostraw, carbon nanotube probes and other nanomaterial. In this context, particular attentions will be paid to their principles, preparations, operations, superiorities and drawbacks, and meanwhile the great potential of nano-materials for single-cell sampling will also be highlighted and prospected.

7.
Chem Res Toxicol ; 33(5): 1055-1060, 2020 05 18.
Artigo em Inglês | MEDLINE | ID: mdl-32223181

RESUMO

Engineered nanoparticles (ENPs) may cause toxicity if they cross various biological barriers and are accumulated in vital organs. Which factors affect barrier crossing efficiency of ENPs are crucial to understand. Here, we present strong data showing that various nanoparticles crossed biological barriers to enter vital animal organs and cause toxicity. We also point out that physicochemical properties of ENPs, modifications of ENPs in biofluid, and physiological and pathological conditions of the body all affect barrier crossing efficiency. We also summarized our limited understanding of the related mechanisms. On the basis of this summary, major research gaps and direction of further efforts are then discussed.

8.
Front Chem ; 8: 123, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32181240

RESUMO

Low-cost and earth-abundant coal has been considered to have a unique structural superiority as carbon sources of carbon quantum dots (CQDs). However, it is still difficult to obtain CQDs from raw coal due to its compactibility and lower reactivity, and the majority of the current coal-based CQDs usually emit green or blue fluorescence. Herein, a facile two-step oxidation approach (K2FeO4 pre-oxidation and H2O2 oxidation) was proposed to fabricate bandgap tunable CQDs from anthracite. The K2FeO4 pre-oxidation can not only weaken the non-bonding forces among coal molecules which cause the expansion of coal particles, but also form a large number of active sites on the surface of coal particles. The above effects make the bandgap tunable CQDs (blue, green, or yellow fluorescence) can be quickly obtained from anthracite within 1 h in the following H2O2 oxidation by simply adjusting the concentration of H2O2. All the as-prepared CQDs contain more than 30 at% oxygen, and the average diameters of which are <10 nm. The results also indicate that the high oxygen content only can create new energy states inside the band gap of CQDs with average diameter more than 3.2 ± 0.9 nm, which make the as-prepared CQDs emit green or yellow fluorescence.

9.
ACS Appl Mater Interfaces ; 12(4): 4463-4472, 2020 Jan 29.
Artigo em Inglês | MEDLINE | ID: mdl-31913599

RESUMO

The oxygen reduction reaction (ORR) is an extremely important reaction in many renewable energy-related devices. The sluggish kinetics of the ORR limits the development of many fuel cells. Design and synthesis of highly efficient nonprecious electrocatalysts are of vital importance for electrochemical reduction of oxygen. Herein, we develop a graphitic carbon nitride (g-C3N4)-derived bamboo-like carbon nanotubes/carbon-wrapped Co nanoparticles (BCNT/Co) electrocatalyst by a simple high-temperature pyrolysis and acid-leaching method. The catalytic performance of the as-designed electrocatalyst toward ORR outperforms the commercial Pt/C catalyst in alkaline solution. The onset potential of nonprecious BCNT/Co-800 catalyst was 1.12 V. The half-wave potential was 0.881 V. The result was superior to that of commercial Pt/C (0.827 V vs RHE). The Co nanoparticles, bamboo-like carbon nanotubes, defects, and Co-Nx active sites all result in the remarkable ORR activity, stability, and great methanol tolerance.

10.
Nanotechnology ; 31(12): 125404, 2020 Mar 20.
Artigo em Inglês | MEDLINE | ID: mdl-31766041

RESUMO

Herein, we design a dual-template-assisted pyrolysis method to prepare ultra-small Fe3O4 nanoparticles anchored on Fe/N-doped hollow porous carbon spheres (0.010-Fe/NHPCS-800) for oxygen reduction reaction (ORR). The synthesized SiO2 nanospheres, which are selected as the hard template, contribute to forming macroporous structure. Pluronic ® F127 is employed to fabricate mesopores through high-temperature pyrolysis as a soft template. In this way, the 0.010-Fe/NHPCS-800 architecture represents an ordered hierarchically porous property with a large BET surface area (1812 m2 g-1), which can facilitate the mass transport of reactants and increase the electrochemically active area. The Fe3O4 nanoparticles wrapped by graphitic carbon layers provide more active sites, and the synergistic interaction between Fe3O4 nanoparticles and doping N has a positive effect on ORR performance. The 0.010-Fe/NHPCS-800 catalyst outperforms the most effective ORR activities among a series of Fe/NHPCS samples with onset potential of 0.95 V (versus reversible hydrogen potential) and half-wave potential of 0.81 V, which is almost the same as the commercial Pt/C (0.96 and 0.81 V, correspondingly) in 0.10 M KOH. However, both the stability and durability of 0.010-Fe/NHPCS-800 surpass those of commercial Pt/C. Given all these advantages, 0.010-Fe/NHPCS-800 is a promising candidate to take the place of Pt-based electrocatalysts for ORR in the future.

11.
Ecotoxicol Environ Saf ; 189: 109956, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31761550

RESUMO

Synergistic toxicity from multiple environmental pollutants poses greater threat to humans, especially to susceptible pregnant population. Here we evaluated combined toxicity from environment pollutants zinc oxide nanoparticles (ZnO NPs) and cadmium chloride (CdCl2) using two pregnant mice models established by oral administration during peri-implantation or organogenesis period. We found that exposures to combined pollutants only at organogenesis stage induced higher fetal deformity rate compared to co-exposures at peri-implantation stage. We further discovered that surface charge of ZnO NPs were modified after Cd2+ adsorption and the resulting nanoadducts caused more severe damages in placental barriers by causing shed endothelial cells and decreased expressions of tight junction proteins ZO1, occludin, claudin-4 and claudin-8. These cellular and molecular events enhanced maternal-fetal transfer of both pollutants and aggravated embryotoxicity. Our findings help elucidate synergistic embryotoxicity by nanoparticle/pollutant adducts and establish proper safety criteria for pregnant population in an era that nanotechnology-based products are widely used.


Assuntos
Cloreto de Cádmio/toxicidade , Poluentes Ambientais/toxicidade , Nanopartículas Metálicas/toxicidade , Óxido de Zinco/toxicidade , Administração Oral , Adsorção , Animais , Cloreto de Cádmio/administração & dosagem , Embrião de Mamíferos/efeitos dos fármacos , Células Endoteliais/efeitos dos fármacos , Poluentes Ambientais/administração & dosagem , Feminino , Troca Materno-Fetal , Nanopartículas Metálicas/administração & dosagem , Camundongos , Placenta/efeitos dos fármacos , Gravidez , Proteínas de Junções Íntimas/metabolismo , Óxido de Zinco/administração & dosagem
12.
Ying Yong Sheng Tai Xue Bao ; 31(12): 4017-4026, 2020 Dec.
Artigo em Chinês | MEDLINE | ID: mdl-33393237

RESUMO

A water-controlled experiment with four treatments (no rain, half raining, natural raining and double raining) was carried out in a Platycladus orientalis forest. The factors including soil water content (SWC), precipitation, sap flow density (Js), leaf area index (LAI), vapor pressure deficit (VPD) were monitored during August 2016 to August 2017. We further analyzed the response of canopy stomatal conductance (gs) to changes of SWC. The results showed that the SWC of plots (half, natural and double raining) showed a positive correlation with precipitation, and the range of SWC was 4.9%-16.0%, 7.2%-22.9%, 7.4%-29.6%, respectively. The SWC in the plot with no rain decreased by 50% from August to October. The daily gs reached a peak of 166.64 mmol·m-2·s-1 at 14:00 in July, which was significantly higher than other months. A bimodal phenomenon occurred. The daily gs reached a peak of 54.1 mmol·m-2·s-1 at 12:00 in January. Under the three rain plots, diurnal variation of gs and SWC showed a negative quadratic correlation. The SWC corresponding to the peak of gs was 8.5%, 12.5% and 18.5%, respectively, close to the annual average SWC. Sensitivity (δ) of gs to VPD /reference canopy stomatal conductance (gsref) was more than or equal to 0.6 in different water-controlled plots, indicating that soil water condition was more suitable for water demand of P. orientalis. When SWC was between 3.7% and 7.5%, the δ and gsref increased rapidly, indicating that stomata had better regulation ability, and that plant stomata was more sensitive to VPD. When SWC increased to 11%, SWC alteration did not affect the response sensitivity of gsrefand gs to VPD. There might be a SWC threshold value for the adaptation of P. orientalis. By closing or reducing stomatal aperture, leaf water potential decreased, P. orientalis could adapt to excessive VPD and avoid excessive transpiration, which was more effective in regulating transpiration.


Assuntos
Transpiração Vegetal , Água , Folhas de Planta , Estômatos de Plantas , Solo , Pressão de Vapor
13.
Phys Chem Chem Phys ; 21(29): 16282-16287, 2019 Aug 07.
Artigo em Inglês | MEDLINE | ID: mdl-31304504

RESUMO

Antibiotic contamination in water has become an increasingly serious problem that poses a potentially huge threat to human health. Ofloxacin (OFL) is a typical broad-spectrum quinolone antibiotic and is frequently detected in a wide variety of aquatic environments. Given its frequent contamination, the need for new electrochemical sensors to quickly and efficiently detect OFL in aquatic environments has attracted increasing attention. Solution pH is an important factor affecting the performance of electrochemical sensors. This work investigates OFL detection using graphene/glassy carbon electrodes (Gr/GCE) in phosphate-buffered saline across a range of pH (3-8). The molecular polarity analysis method was first used to reveal interactions between target contaminants and the electrode interface. The electrode properties and the polarity of OFL were studied using SEM, XPS, FT-IR spectrometry, zeta potentiometry and modelling calculation of molecular properties. Our results showed that OFL interacts with the surface of Gr/GCE via both hydrogen bonding and coulomb electrostatic forces. The electrical signal decreased more quickly in an alkaline than acidic environment, which was due to the differences between coulomb electrostatic and hydrogen bonding forces. These results also showed variations in the OFL peak current response under different pH conditions. Collectively, these findings provide a better foundation for the rapid identification of the optimal pH environment for the electrical analysis of contaminants like antibiotics in an aquatic environment.

14.
Ecotoxicol Environ Saf ; 182: 109439, 2019 Oct 30.
Artigo em Inglês | MEDLINE | ID: mdl-31306920

RESUMO

The widespread application of nanomaterial-based products has caused safety concerns worldwide, especially for susceptible pregnant population. Here, we revealed the effect of the size of ZnO nanoparticles (ZnO NPs) on placental and fetal developmental toxicities. We found that smaller ZnO NPs (13 nm) were able to cross both the intestinal barrier and the placental barrier to reach the fetus after oral exposure and caused fetal developmental toxicity. However, larger ZnO NPs (57 nm) and bulk ZnO particles were not able to cross these barriers and exert effects. We also discovered that the organogenesis period (GD7-GD16) was more vulnerable to such toxicity compared with the peri-implantation period (GD1-GD10) of pregnancy. This new understanding that smaller nanoparticles may pass through multiple biological barriers to induce toxicity in susceptible populations is crucial for the safeguarding of humans from the widespread application of nanoproducts. The discovery that the organogenesis stage in pregnancy is more vulnerable to nanotoxicity than the peri-implantation stage is provides valuable guidance for an improved protection strategy.


Assuntos
Desenvolvimento Fetal/efeitos dos fármacos , Nanopartículas/toxicidade , Óxido de Zinco/toxicidade , Animais , Feminino , Intestinos , Camundongos , Gravidez
15.
Environ Pollut ; 252(Pt A): 856-862, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31202138

RESUMO

Neonicotinoid insecticides have been widely used throughout the world over the last two decades. In the present study, we investigated the degradation of neonicotinoid insecticides nitenpyram (NIT) and dinotefuran (DIN) by the white-rot fungus Phanerochaete sordida YK-624. While NIT was completely degraded by P. sordida YK-624 under ligninolytic conditions, only a 20% decrease was observed under nonligninolytic conditions. On the other hand, P. sordida YK-624 degraded 31% of DIN under ligninolytic conditions after a 20-day incubation, while it did not degrade DIN under nonligninolytic conditions. We found that cytochromes P450 played a key role in the biotransformation of NIT and DIN by P. sordida YK-624. A novel NIT metabolite (E)-N-((6-chloropyridin-3-yl)methyl)-N-ethyl-N'-hydroxy acetimidamide (CPMHA) and a novel DIN metabolite N-((4aS,7aS,E)-1-methylhexahydrofuro[2,3-d]pyrimidin-2(1H)-ylidene)nitramide (PHPF) were identified in this study. In addition, to evaluate neurotoxicity, the effects of NIT, DIN and their metabolites on the viability of human neuroblastoma cells SH-SY5Y were determined. PHPF showed higher neurological toxicity than DIN, whereas the metabolite of NIT, CPMHA, showed no toxic effect. Our results indicated that the neurological toxicity of NIT could be effectively removed by P. sordida YK-624.


Assuntos
Biodegradação Ambiental , Guanidinas/metabolismo , Inativação Metabólica/fisiologia , Inseticidas/metabolismo , Neonicotinoides/metabolismo , Nitrocompostos/metabolismo , Phanerochaete/metabolismo , Linhagem Celular Tumoral , Sistema Enzimático do Citocromo P-450/metabolismo , Humanos , Neurotoxinas/metabolismo
16.
Chem Commun (Camb) ; 55(39): 5651-5654, 2019 May 09.
Artigo em Inglês | MEDLINE | ID: mdl-31025990

RESUMO

This report presents a simple method to produce an ultrasmall-Fe7C3/N-doped porous carbon hybrid (u-Fe7C3@NC) as an excellent oxygen reduction reaction (ORR) electrocatalyst. A zinc-air battery assembled with u-Fe7C3@NC performs at a higher open potential (1.486 V) and at a lower discharge overpotential compared with the commercial Pt/C catalyst.

17.
Ecotoxicol Environ Saf ; 172: 152-158, 2019 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-30708226

RESUMO

The composition of PM2.5 is extremely complicated, making the causes of PM2.5-induced toxicity hard to understand. To identify the major toxic components of PM2.5 particles, we used reductionism approach, synthesized and investigated a model PM2.5 library containing 24 carbon nanoparticles with adsorbed pollutants including Cr(VI), Pb2+, As(III) and BaP either individually or in combinations. Our data showed that major physicochemical characteristics of model PM2.5 library members were similar to PM2.5 particles from Guangzhou city (PM2.5-GZ). Cytotoxicity of lung cells (A549) was increasing as the member of adsorbed pollutants at environment relevant concentrations. Using these model particles, we identified that co-existence of Cr(VI) and Pb2+ components contributed to the PM2.5-induced cytotoxicity in A549 cells. Besides, pulmonary surfactant reduced the PM2.5-induced cytotoxicity in A549 cells probably via enhancing cell autophagy. The findings from this study suggest that systematic investigation using model PM2.5 particle library helps identify key toxic pollutants in otherwise very complex PM2.5 particles and facilitate our understanding of the underlying biological mechanisms.


Assuntos
Poluentes Atmosféricos/toxicidade , Cromo/toxicidade , Chumbo/toxicidade , Nanopartículas/toxicidade , Material Particulado/toxicidade , Substâncias Protetoras/farmacologia , Surfactantes Pulmonares/farmacologia , Células A549 , Poluentes Atmosféricos/análise , Autofagia , Cromo/química , Cidades , Exposição Ambiental , Humanos , Chumbo/química , Pulmão/química , Tamanho da Partícula , Material Particulado/química , Testes de Toxicidade/métodos
18.
Mikrochim Acta ; 186(2): 74, 2019 01 09.
Artigo em Inglês | MEDLINE | ID: mdl-30627840

RESUMO

The authors report that CuOx/NiOy hollow nanocomposites are an effective bifunctional catalyst capable of oxidizing glucose and reducing hydrogen peroxide. Synthesis is based on a solvothermal process and subsequent thermal treatment. The structure can be controlled by adjusting the amounts of added NiCl2 during the solvothermal etching process, and core-shell, yolk-shell or hollow structures can be obtained. The porous hollow structure composite of type CuO30/NiO90 was used to modify a glassy carbon electrode. It exhibits excellent electrocatalytic activity towards glucose oxidation in solution of pH 13, typically at a working potential of +0.60 V (vs. Ag/AgCl). This enables voltammetric sensing of glucose with (a) a low limit of detection (0.08 µM, at S/N = 3), (b) over a wide linear range (0.20 µM - 2.5 mM), and (c) high sensitivity (2043 µA·mM-1·cm-2). The sensor is reproducible, selective and stable. It can be used to detect glucose in spiked human serum. The CuO30/NiO90 composite also displays good electrocatalytic activity towards reduction of H2O2 in neutral aqueous medium, typically at an applied potential of -0.35 V. It has a detection limit of 90 nM, a sensitivity of 271.1 µA·mM-1·cm-2, and a linear detection range that extends from 0.30 µM to 9.0 mM. Graphical abstract CuOx/NiOy nanocomposites with three different structures were synthesized by coordinated etching precipitation method. The hollow structure CuO30/NiO90 was coated on the surface of glassy carbon electrode for the amperometric determination of glucose and hydrogen peroxide.

19.
ACS Appl Mater Interfaces ; 11(7): 6829-6839, 2019 Feb 20.
Artigo em Inglês | MEDLINE | ID: mdl-30694645

RESUMO

The ability of nanoparticles to induce adverse consequences in human cells relies on their physical shapes. In this aspect, how two-dimensional nanoparticles differ from three-dimensional nanoparticles is not well-known. To elucidate this difference, combined experimental and theoretical approaches are employed to compare MoS2 nanosheets with 5-layer and 40-layer thicknesses for their cellular effects and the associated molecular events. At a concentration as defined by the nanosheet surface areas (10 cm2/mL), 40-layer nanosheets are internalized by cells, whereas 5-layer nanosheets mostly bind to the cell surface without internalization. Although they alter different autophagy-related genes, a common mechanism is that they both perturb cell surface protein amyloid precursor proteins and activate the mTOR signaling pathway. Our findings prove that the perturbation of cellular function without nanoparticle internalization has significant nanomedicinal and nanotoxicological significances.


Assuntos
Autofagia/efeitos dos fármacos , Dissulfetos , Molibdênio , Nanopartículas , Proteínas de Neoplasias/metabolismo , Neoplasias , Transdução de Sinais/efeitos dos fármacos , Serina-Treonina Quinases TOR/metabolismo , Linhagem Celular Tumoral , Dissulfetos/química , Dissulfetos/farmacologia , Humanos , Molibdênio/química , Molibdênio/farmacologia , Nanopartículas/química , Nanopartículas/uso terapêutico , Neoplasias/tratamento farmacológico , Neoplasias/metabolismo , Neoplasias/patologia , Receptores de Superfície Celular/metabolismo
20.
Nanotechnology ; 30(7): 075402, 2019 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-30523950

RESUMO

The design of high-efficient and durable bi-functional oxygen electrocatalysts is still a great challenge. In this work, novel Co9S8 nanoparticles/N,S-codoped defect-rich carbon nanotubes (Co9S8/N,S-CNTs) were fabricated by an ingenious template method. CdS nanowires, as a sacrificial template, can be removed simultaneously during the carbonization process without additional post-treatments. The large BET surface area (661.2 m2 g-1) and pore volume (1.49 cm3 g-1) of Co9S8/N,S-CNTs could largely enhance the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) activities by facilitating the mass transportation and exposing more active sites. The abundant defects produced by the evaporation of Cd and S doping could provide more active sites for ORR and OER. Coupling with Co9S8, Co9S8/N,S-CNTs possesses more defects in the carbon skeleton, better electron conductivity, and larger effective electrochemical area. Co9S8/N,S-CNTs not only performs excellent ORR activity with a half-wave potential of 0.821 V but also owns RuO2-like OER activity in alkaline solution. The potential difference (ΔE) between ORR and OER is as low as 0.78 V in 0.10 M KOH. The excellent bi-functional performance enables the potential to be utilized in fuel cells and metal-air batteries.

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