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2.
Nat Commun ; 9(1): 4614, 2018 11 05.
Artigo em Inglês | MEDLINE | ID: mdl-30397203

RESUMO

The electrochemical reduction of carbon monoxide is a promising approach for the renewable production of carbon-based fuels and chemicals. Copper shows activity toward multi-carbon products from CO reduction, with reaction selectivity favoring two-carbon products; however, efficient conversion of CO to higher carbon products such as n-propanol, a liquid fuel, has yet to be achieved. We hypothesize that copper adparticles, possessing a high density of under-coordinated atoms, could serve as preferential sites for n-propanol formation. Density functional theory calculations suggest that copper adparticles increase CO binding energy and stabilize two-carbon intermediates, facilitating coupling between adsorbed *CO and two-carbon intermediates to form three-carbon products. We form adparticle-covered catalysts in-situ by mediating catalyst growth with strong CO chemisorption. The new catalysts exhibit an n-propanol Faradaic efficiency of 23% from CO reduction at an n-propanol partial current density of 11 mA cm-2.

3.
Biomaterials ; 31(21): 5575-87, 2010 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-20427083

RESUMO

The interaction of ultra-nanocrystalline diamond (UNCD) with neural stem cells (NSCs) has been studied in order to evaluate its potential as a biomaterial. Hydrogen-terminated UNCD (H-UNCD) films were compared with standard grade polystyrene in terms of their impact on the differentiation of NSCs. When NSCs were cultured on these substrates in medium supplemented with low concentration of serum and without any differentiating factors, H-UNCD films spontaneously induced neuronal differentiation on NSCs. By direct suppression of mitogen-activated protein kinase/extracellular signaling-regulated kinase1/2 (MAPK/Erk1/2) signaling pathway in NSCs using U0126, known to inhibit the activation of Erk1/2, we demonstrated that the enhancement of Erk1/2 pathway is one of the effects of H-UNCD-induced NSCs differentiation. Moreover, functional-blocking antibody directed against integrin beta1 subunit inhibited neuronal differentiation on H-UNCD films. This result demonstrated the involvement of integrin beta1 in H-UNCD-mediated neuronal differentiation. Mechanistic studies revealed the cell adhesion to H-UNCD films associated with focal adhesion kinase (Fak) and initiated MAPK/Erk1/2 signaling. Our study demonstrated that H-UNCD films-mediated NSCs differentiation involves fibronectin-integrin beta1 and Fak-MAPK/Erk signaling pathways in the absence of differentiation factors. These observations raise the potential for the use of UNCD as a biomaterial for central nervous system transplantation and tissue engineering.


Assuntos
Diferenciação Celular/fisiologia , Diamante/química , Nanopartículas/química , Neurônios/fisiologia , Células-Tronco/fisiologia , Animais , Biomarcadores/metabolismo , Butadienos/metabolismo , Adesão Celular , Células Cultivadas , Materiais Revestidos Biocompatíveis/química , Inibidores Enzimáticos/metabolismo , MAP Quinases Reguladas por Sinal Extracelular/metabolismo , Fibronectinas/metabolismo , Quinase 1 de Adesão Focal/metabolismo , Integrina beta1/metabolismo , Teste de Materiais , Camundongos , Neurônios/citologia , Nitrilas/metabolismo , Transdução de Sinais/fisiologia , Células-Tronco/citologia , Propriedades de Superfície
4.
Biomaterials ; 30(20): 3428-35, 2009 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-19406465

RESUMO

The interaction of ultra-nanocrystalline diamond (UNCD) with neural stem cells (NSCs) has been studied along with its surface modification in order to improve its function as a biomaterial. Hydrogen- and oxygen-terminated UNCD films were compared with standard grade polystyrene in terms of their impact on the growth, expansion and differentiation of NSCs. When NSCs were cultured on these substrates in low serum and without any differentiating factors, hydrogen-terminated UNCD films spontaneously induced cell proliferation and neuronal differentiation. Oxygen-terminated UNCD films were also shown to further improve neural differentiation, with a preference to differentiate into oligodendrocytes. Hence, controlling the surface properties of UNCD could manipulate the differentiation of NSCs for different biomedical applications. These observations raise the potential for the use of UNCD as a biomaterial for central nervous system transplantation and tissue engineering.


Assuntos
Técnicas de Cultura de Células/instrumentação , Diferenciação Celular/fisiologia , Proliferação de Células , Diamante/química , Neurônios/fisiologia , Células-Tronco/fisiologia , Animais , Materiais Biocompatíveis/química , Materiais Biocompatíveis/metabolismo , Forma Celular , Células Cultivadas , Humanos , Teste de Materiais , Camundongos , Neurônios/citologia , Poliestirenos/química , Células-Tronco/citologia , Propriedades de Superfície , Tubulina (Proteína)/metabolismo
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