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J Am Chem Soc ; 131(38): 13586-7, 2009 Sep 30.
Artigo em Inglês | MEDLINE | ID: mdl-19736938


We report the development of phototriggerable microcapsules and demonstrate the concept of protection and remote release of chemical species. Light-rupturable, liquid-filled microcapsules were prepared by coencapsulation of carbon nanotubes using a simple and robust interfacial polymerization technique. The incorporation of carbon nanotubes endows the microcapsules with the ability to respond to an external optical event. The triggered release of the liquid contents for the microcapsules may be achieved either in air or within a liquid medium via irradiation with a near-IR laser. Rupture of the impermeable shell-wall under irradiation is presumed to be due to an increase in internal pressure due to optothermal heating of the CNTs. The storage and triggered release of reactive small molecules and catalysts was demonstrated in the context of remotely initiated "click" reaction and ring-opening metathesis polymerization.

Cápsulas/química , Luz , Nanotubos de Carbono/química , Lasers , Microscopia Eletrônica de Varredura , Nylons/química , Processos Fotoquímicos , Tolueno/química
J Am Chem Soc ; 131(3): 890-1, 2009 Jan 28.
Artigo em Inglês | MEDLINE | ID: mdl-19119844


We report the discovery that boron nitride nanotubes (BNNTs), isosteres of CNTs with unique physical properties, are inherently noncytotoxic. Furthermore, we developed a biomemetic coating strategy to interface BNNTs with proteins and cells. Finally, we showed that BNNTs can deliver DNA oligomers to the interior of cells with no apparent toxicity. This work suggests that BNNTs may be superior to CNTs for use as biological probes and in biomaterials.

Compostos de Boro/química , Nanotubos/química , Proteínas/química , Compostos de Boro/toxicidade , Linhagem Celular , Proliferação de Células/efeitos dos fármacos , Humanos
J Am Chem Soc ; 131(15): 5396-8, 2009 Apr 22.
Artigo em Inglês | MEDLINE | ID: mdl-20560635


As energy demands increase, new, more direct, energy collection and utilization processes must be explored. We present a system that intrinsically combines the absorption of sunlight with the production of useful work in the form of locomotion of objects on liquids. Focused sunlight is locally absorbed by a nanostructured composite, creating a thermal surface tension gradient and, subsequently, motion. Controlled linear motion and rotational motion are demonstrated. The system is scale independent, with remotely powered and controlled motion shown for objects in the milligram to tens of grams range.

Fontes Geradoras de Energia , Movimento (Física) , Luz Solar , Tensão Superficial , Nanocompostos/efeitos da radiação , Fenômenos Físicos , Rotação , Energia Solar
J Am Chem Soc ; 130(13): 4238-9, 2008 Apr 02.
Artigo em Inglês | MEDLINE | ID: mdl-18331043


A facile patterning method for the functionalization of vertically aligned carbon nanotubes is described. Modification of the surface of nanotube forests with hydrophilic, hydrophobic, or polymerizable small molecules was achieved via UV-triggered attachment of perfluoroarylazides. Multiple functionalizations of the tube surface can be achieved. Macro- and micropatterning of forest substrates were demonstrated. Superhydrophobic surfaces containing superhydrophilic regions were prepared.

Azidas/química , Nanotubos de Carbono/química , Azidas/efeitos da radiação , Interações Hidrofóbicas e Hidrofílicas , Nanotubos de Carbono/efeitos da radiação , Tamanho da Partícula , Propriedades de Superfície , Raios Ultravioleta , Molhabilidade
ACS Chem Biol ; 1(8): 525-33, 2006 Sep 19.
Artigo em Inglês | MEDLINE | ID: mdl-17168540


Designed second mitochondrial activator of caspases (Smac) mimetics based on an accessible [7,5]-bicyclic scaffold bind to and antagonize protein interactions involving the inhibitor of apoptosis (IAP) proteins, X-chromosome-linked IAP (XIAP), melanoma IAP (ML-IAP), and c-IAPs 1 and 2 (cIAP1 and cIAP2). The design rationale is based on a combination of phage-panning data, peptide binding studies, and a survey of potential isosteres. The synthesis of two scaffolds is described. These compounds bind the XIAP-baculoviral IAP repeat 3 (BIR3), cIAP1-BIR3, cIAP2-BIR3, and ML-IAP-BIR domains with submicromolar affinities. The most potent Smac mimetic binds the cIAP1-BIR3 and ML-IAP-BIR domains with a K i of 50 nM. The X-ray crystal structure of this compound bound to an ML-IAP/XIAP chimeric BIR domain protein is compared with that of a complex with a phage-derived tetrapeptide, AVPW. The structures show that these compounds bind to the Smac-binding site on ML-IAP with identical hydrogen-bonding patterns and similar hydrophobic interactions. Consistent with the structural data, coimmunoprecipitation experiments demonstrate that the compounds can effectively block Smac interactions with ML-IAP. The compounds are further demonstrated to activate caspase-3 and -7, to reduce cell viability in assays using MDA-MB-231 breast cancer cells and A2058 melanoma cells, and to enhance doxorubicin-induced apoptosis in MDA-MB-231 cells.

Apoptose/efeitos dos fármacos , Materiais Biomiméticos/farmacologia , Desenho de Fármacos , Proteínas Inibidoras de Apoptose/antagonistas & inibidores , Peptídeos e Proteínas de Sinalização Intracelular/química , Neoplasias/metabolismo , Neoplasias/patologia , Sítios de Ligação , Materiais Biomiméticos/síntese química , Materiais Biomiméticos/química , Caspases/metabolismo , Linhagem Celular , Cristalografia por Raios X , Ativação Enzimática/efeitos dos fármacos , Humanos , Proteínas Inibidoras de Apoptose/metabolismo , Peptídeos e Proteínas de Sinalização Intracelular/metabolismo , Modelos Moleculares , Neoplasias/genética , Ligação Proteica , Estrutura Terciária de Proteína
Biochemistry ; 42(27): 8223-31, 2003 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-12846571


Melanoma inhibitor of apoptosis (ML-IAP) is a potent anti-apoptotic protein that is upregulated in a number of melanoma cell lines but not expressed in most normal adult tissues. Overexpression of IAP proteins, such as ML-IAP or the ubiquitously expressed X-chromosome-linked IAP (XIAP), in human cancers has been shown to suppress apoptosis induced by a variety of stimuli. Peptides based on the processed N-terminus of Smac/DIABLO can negate the ability of overexpressed ML-IAP or XIAP to suppress drug-induced apoptosis. Such peptides have been demonstrated to bind to the single baculovirus IAP repeat (BIR) of ML-IAP and the third BIR of XIAP with similar high affinities (approximately 0.5 microM). Herein, we use phage-display of naïve peptide libraries and synthetic peptides to investigate the peptide-binding properties of ML-IAP-BIR and XIAP-BIR3. X-ray crystal structures of ML-IAP-BIR in complex with Smac- and phage-derived peptides, together with peptide structure-activity-relationship data, indicate that the peptides can be modified to provide increased binding affinity and selectivity for ML-IAP-BIR relative to XIAP-BIR3. For instance, substitution of Pro3' in the Smac-based peptide (AVPIAQKSE) with (2S,3S)-3-methylpyrrolidine-2-carboxylic acid [(3S)-methyl-proline] results in a peptide with 7-fold greater affinity for ML-IAP-BIR and about 100-fold specificity for ML-IAP-BIR relative to XIAP-BIR3.

Proteínas Adaptadoras de Transdução de Sinal , Proteínas de Transporte/química , Proteínas de Transporte/fisiologia , Proteínas de Neoplasias/química , Proteínas de Neoplasias/fisiologia , Sequência de Aminoácidos , Proteínas de Transporte/genética , Cristalografia por Raios X , Ligação Genética , Proteínas Inibidoras de Apoptose , Modelos Moleculares , Dados de Sequência Molecular , Proteínas de Neoplasias/genética , Homologia de Sequência de Aminoácidos , Relação Estrutura-Atividade , Cromossomo X