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1.
Molecules ; 24(19)2019 Sep 30.
Artigo em Inglês | MEDLINE | ID: mdl-31575030

RESUMO

The Pd-catalyzed intramolecular carbene C-H insertion of α-diazo-α-(methoxycarbonyl)acetamides to prepare oxindoles as well as ß-lactams was studied. In order to identify what factors influence the selectivity of the processes, we explored how the reactions are affected by the catalyst type, using two oxidation states of Pd and a variety of ligands. It was found that, in the synthesis of oxindoles, ((IMes)Pd(NQ))2 can be used as an alternative to Pd2(dba)3 to catalyze the carbene CArsp2-H insertion, although it was less versatile. On the other hand, it was demonstrated that the Csp3-H insertion leading to ß-lactams can be effectively promoted by both Pd(0) and Pd(II) catalysts, the latter being most efficient. Insight into the reaction mechanisms involved in these transformations was provided by DFT calculations.


Assuntos
Acetamidas/química , Compostos de Diazônio/química , Paládio/química , Catálise , Modelos Moleculares , Estrutura Molecular , Oxindois/metabolismo , Paládio/metabolismo , beta-Lactamas/metabolismo
2.
Biosensors (Basel) ; 9(3)2019 Jul 17.
Artigo em Inglês | MEDLINE | ID: mdl-31319551

RESUMO

Altered growth hormone (GH) levels represent a major global health challenge that would benefit from advances in screening methods that are rapid and low cost. Here, we present a miniaturized immunosensor using disposable screen-printed carbon electrodes (SPCEs) for the detection of GH with high sensitivity. The diazonium-based linker layer was electrochemically deposited onto SPCE surfaces, and subsequently activated using covalent agents to immobilize monoclonal anti-GH antibodies as the sensing layer. The surface modifications were monitored using contact angle measurements and X-ray photoelectron spectroscopy (XPS). The dissociation constant, Kd, of the anti-GH antibodies was also determined as 1.44 (±0.15) using surface plasmon resonance (SPR). The immunosensor was able to detect GH in the picomolar range using a 20 µL sample volume in connection with electrochemical impedance spectroscopy (EIS). The selectivity of the SPCE-based immunosensors was also challenged with whole blood and serum samples collected at various development stages of rats, demonstrating the potential applicability for detection in biological samples. Our results demonstrated that SPCEs provided the development of low-cost and single-use electrochemical immunosensors in comparison with glassy carbon electrode (GCE)-based ones.


Assuntos
Técnicas Biossensoriais , Compostos de Diazônio/química , Eletrodos , Hormônio do Crescimento/sangue , Imunoensaio , Animais , Técnicas Eletroquímicas , Ensaio de Imunoadsorção Enzimática , Imunoensaio/métodos , Ratos , Sensibilidade e Especificidade , Análise Espectral , Ressonância de Plasmônio de Superfície
3.
Molecules ; 24(14)2019 Jul 19.
Artigo em Inglês | MEDLINE | ID: mdl-31330952

RESUMO

The intramolecular C-H insertions of carbenes derived from 2-diazo-2-sulfamoylacetamides were studied. 2-Diazo-2-sulfamoylacetamides were first prepared from chloroacetyl chloride and secondary amines through acylation followed by sequential treatments with sodium sulfite, phosphorus oxychloride, secondary amines, and 4-nitrobenzenesulfonyl azide. The results indicate that: (1) 2-diazo-N,N-dimethyl-2-(N,N-diphenylsulfamoyl)acetamide can take the formal aromatic 1,5-C-H insertion in its N-phenylsulfonamide moiety to afford the corresponding 1,3-dihydrobenzo[c]isothiazole-3-carboxamide 2,2-dioxide derivative; (2) no aliphatic C-H insertions occur for 2-diazo-2-(N,N-dialkylsulfamoyl)acetamides; and (3) for 2-diazo-N-phenyl-2-(N-phenylsulfamoyl)acetamides, the formal aromatic 1,5-C-H insertion in the N-phenylacetamide moiety is favorable to afford the corresponding 3-sulfamoylindolin-2-one derivatives as sole or major products. The intramolecular competitive aromatic 1,5-C-H insertion reactions of 2-diazo-2-sulfamoylacetamides with aryl groups on both amide and sulfonamide groups reveal that the N-aryl substituents on acetamide are more active than those on sulfonamide. The chemoselectivity is controlled by electronic effect of the aryl group.


Assuntos
Acetamidas/química , Compostos de Diazônio/química , Metano/análogos & derivados , Sulfonamidas/química , Carbono , Catálise , Hidrogênio , Metano/química
4.
Colloids Surf B Biointerfaces ; 181: 639-647, 2019 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-31212136

RESUMO

The grafting of 5-iodoisatin heterocycle on a cyclic olefin copolymer (COC) and a gold surface was performed using a heterogeneous phase Sonogashira reaction consisting of coupling 5-iodoisatin with an arylalkyne previously introduced onto the surfaces. This optimized strategy takes advantage of the well-established methodology to functionalize COC or gold surfaces using aryldiazonium surface chemistry. Herein, we reported the first example of an isatin decorated polymeric or metallic surface. The surfaces were analyzed with a combination of techniques such as IR (Infrared spectroscopy), XPS (X-Ray photoelectron spectroscopy) and SPR (surface plasmon resonance). Docking studies showed that isatin and two derivatives interact with AmiC, a dimeric protein produced by Pseudomonas aeruginosa. Bacterial adhesion on isatin-COC platform was also observed. This general strategy for robust surface functionalization represents an easy approach for patterning surfaces with compounds of biological interest, allowing access to a large panel of original biosensors.


Assuntos
Antibacterianos/química , Cicloparafinas/química , Isatina/análogos & derivados , Antibacterianos/farmacologia , Aderência Bacteriana/efeitos dos fármacos , Cicloparafinas/farmacologia , Compostos de Diazônio/química , Ouro/química , Isatina/química , Isatina/farmacologia , Testes de Sensibilidade Microbiana , Estrutura Molecular , Tamanho da Partícula , Pseudomonas aeruginosa/efeitos dos fármacos , Propriedades de Superfície
5.
Bioconjug Chem ; 30(4): 1244-1257, 2019 04 17.
Artigo em Inglês | MEDLINE | ID: mdl-30874432

RESUMO

Oncolytic viruses offer many advantages for cancer therapy when administered directly to confined solid tumors. However, the systemic delivery of these viruses is problematic because of the host immune response, undesired interactions with blood components, and inherent targeting to the liver. Efficacy of systemically administered viruses has been improved by masking viral surface proteins with polymeric materials resulting in modulation of viral pharmacokinetic profile and accumulation in tumors in vivo. Here we describe a new class of polyvalent reactive polymer based on poly( N-(2-hydroxypropyl)methacrylamide) (polyHPMA) with diazonium reactive groups and their application in the modification of the chimeric group B oncolytic virus enadenotucirev (EnAd). A series of six copolymers with different chain lengths and density of reactive groups was synthesized and used to coat EnAd. Polymer coating was found to be extremely efficient with concentrations as low as 1 mg/mL resulting in complete (>99%) ablation of neutralizing antibody binding. Coating efficiency was found to be dependent on both chain length and reactive group density. Coated viruses were found to have reduced transfection activity both in vitro and in vivo, with greater protection against neutralizing antibodies resulting in lower transgene production. However, in the presence of neutralizing antibodies, some in vivo transgene expression was maintained for coated virus compared to the uncoated control. The decrease in transgene expression was found not to be solely due to lower cellular uptake but due to reduced unpackaging of the virus within the cells and reduced replication, indicating that the polymer coating does not cause permanent inactivation of the virus. These data suggest that virus activity may be modulated by the appropriate design of coating polymers while retaining protection against neutralizing antibodies.


Assuntos
Adenoviridae/imunologia , Anticorpos Neutralizantes/imunologia , Compostos de Diazônio/farmacologia , Terapia Viral Oncolítica , Polímeros/farmacologia , Linhagem Celular Tumoral , Compostos de Diazônio/química , Vetores Genéticos , Humanos , Polímeros/química , Transfecção
6.
Molecules ; 24(2)2019 Jan 14.
Artigo em Inglês | MEDLINE | ID: mdl-30646524

RESUMO

7-Oxo-1,2,4-benzotriazines (benzo[1,2,4]triazin-7-ones) are reversible thioredoxin reductase inhibitors that exhibit very strong correlations to pleurotin. In this article, we provide the first synthesis of fluorinated derivatives. Fluorination using Selectfluor of benzo[1,2,4]triazin-7-ones occurs regioselectively and in high yield at the enamine-activated position. This electron N-lone pair activation overrides the activation/deactivation effects of some other substituents. The reaction time was significantly reduced with the use of microwave irradiation at 120 °C and 7 bar. The cytotoxicity and cyclic voltammetry measurements for 8-fluoro-1,3-diphenylbenzo[e][1,2,4]triazin-7(1H)-one (2) are presented and compared with its synthetic precursor, 1,3-diphenylbenzo[e][1,2,4]triazin-7(1H)-one (1a).


Assuntos
Compostos de Diazônio/química , Triazinas/química , Antineoplásicos/química , Antineoplásicos/farmacologia , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Halogenação , Humanos , Concentração Inibidora 50 , Espectroscopia de Ressonância Magnética , Estrutura Molecular , Relação Estrutura-Atividade , Triazinas/farmacologia
7.
Methods Mol Biol ; 1870: 81-87, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30539548

RESUMO

Introduction of chemical labels into biomolecules is of utmost importance in chemical biology research. However, methods for selective chemical labeling of in vitro transcribed RNA are scarce. Herein, we describe experimental details for direct labeling of the 5'-phosphate of RNA using a diazo biotin-reagent, as exemplified on a 110 nucleotide RNA obtained via in vitro transcription. The method exploits the fact that, under neutral buffer conditions (~pH 6.8), the 5'-phosphate carries the only mildly acidic proton in the RNA molecule, which allows for selective functionalization at that site using diazo reagents.


Assuntos
Biotina/química , Biotinilação , Compostos de Diazônio/química , RNA/química , Biotinilação/métodos , Cromatografia Líquida , Espectrometria de Massas , Estrutura Molecular , RNA/isolamento & purificação , Coloração e Rotulagem
8.
Org Biomol Chem ; 17(1): 88-102, 2018 12 19.
Artigo em Inglês | MEDLINE | ID: mdl-30520486

RESUMO

The marine natural products cyclomarins have remarkable anti-mycobacterial and antiplasmodial activities. The heptapeptic structure of this compound class comprisis four highly interesting non-canonical amino acids, including a rather unusual syn ß-methoxyphenylalanine. To get a deeper insight into the structure-activity realtionship of cyclomarines, a straightforward protocol for the stereoselective synthesis of this building block was developed, based on diazonium chemistry.


Assuntos
Aminoácidos/química , Compostos de Diazônio/química , Peptídeos Cíclicos/química , Fenilalanina/química , Antibacterianos/síntese química , Antiprotozoários/síntese química , Produtos Biológicos/química , Biologia Marinha , Estereoisomerismo , Relação Estrutura-Atividade
9.
ACS Nano ; 12(10): 9922-9930, 2018 10 23.
Artigo em Inglês | MEDLINE | ID: mdl-30260623

RESUMO

Single-point-functionalized carbon-nanotube field-effect transistors (CNTFETs) have been used to sense conformational changes and binding events in protein and nucleic acid structures from intrinsic molecular charge. The key to utilizing these devices as single-molecule sensors is the ability to attach a single probe molecule to an individual device. In contrast, with noncovalent attachment approaches such as those based on van der Waals interactions, covalent attachment approaches generally deliver higher stability but have traditionally been more difficult to control, resulting in low yield. Here, we present a single-point-functionalization method for CNTFET arrays based on electrochemical control of a diazonium reaction to create sp3 defects, combined with a scalable spin-casting method for fabricating large arrays of devices on arbitrary substrates.  Attachment of probe DNA to the functionalized device enables single-molecule detection of DNA hybridization with complementary target, verifying the single-point functionalization. Overall, this method enables single-point defect generation with 80% yield.


Assuntos
Técnicas Eletroquímicas , Nanotubos de Carbono/química , Transistores Eletrônicos , DNA/química , Sondas de DNA/química , Compostos de Diazônio/química , Estrutura Molecular , Hibridização de Ácido Nucleico
10.
Chembiochem ; 19(23): 2443-2447, 2018 12 04.
Artigo em Inglês | MEDLINE | ID: mdl-30212615

RESUMO

The tyrosine side chain is amphiphilic leading to significant variations in the surface exposure of tyrosine residues in the folded structure of a native sequence protein. This variability can be exploited to give residue-selective functionalization of a protein substrate by using a highly reactive diazonium group tethered to an agarose-based resin. This novel catch-and-release approach to protein modification has been demonstrated for proteins with accessible tyrosine residues, which are compared with a control group of proteins in which there are no accessible tyrosine residues. MS analysis of the modified proteins showed that functionalization was highly selective, but reactivity was further attenuated by the electrostatic environment of any individual residue. Automated screening of PDB structures allows identification of potential candidates for selective modification by comparison with the accessibility of the tyrosine residue in a benchmark peptide (GYG).


Assuntos
Proteínas/química , Tirosina/química , Sequência de Aminoácidos , Aminofenóis/síntese química , Aminofenóis/química , Compostos de Diazônio/química , Ferricianetos/química , Fluoresceínas/síntese química , Fluoresceínas/química , Oligopeptídeos/química
11.
ACS Appl Mater Interfaces ; 10(27): 23380-23391, 2018 Jul 11.
Artigo em Inglês | MEDLINE | ID: mdl-29943966

RESUMO

Surface-enhanced infrared absorption spectroscopy is used in situ to determine the electrochemical stability of organic interfaces deposited onto the surface of nanostructured, thin-film gold electrodes via the electrochemical reduction of diazonium salts. These interfaces are shown to exhibit a wide electrochemical stability window in both acetonitrile and phosphate buffer, far surpassing the stability window of thiol-derived self-assembled monolayers. Using the same in situ technique, the application of radical scavengers during the electrochemical reduction of diazonium salts is shown to moderate interface formation. Consequently, the heterogeneous charge-transfer resistance can be reduced sufficiently to enhance the direct electron transfer between an immobilized redox-active enzyme and the electrode. This was demonstrated for the oxygen-tolerant [NiFe] hydrogenase from the "Knallgas" bacterium Ralstonia eutropha by relating its electrochemical activity for hydrogen oxidation to the interface properties.


Assuntos
Técnicas Eletroquímicas/métodos , Enzimas Imobilizadas/química , Ouro/química , Hidrogenase/química , Análise Espectral/métodos , Proteínas de Bactérias/química , Proteínas de Bactérias/metabolismo , Cupriavidus necator/enzimologia , Compostos de Diazônio/química , Eletrodos , Enzimas Imobilizadas/metabolismo , Hidrogenase/metabolismo , Propriedades de Superfície
12.
Environ Sci Pollut Res Int ; 25(20): 20012-20022, 2018 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-29744780

RESUMO

Adhesively bonded polypyrrole thin films doped with benzene sulfonic acid (BSA) were electrodeposited on aminobenzenediazonium-modified flexible ITO electrodes and further employed for the detection of Pb2+, Cu2+, and Cd2+ metal ions in aqueous medium. The aminophenyl (AP) adhesive layer was grafted to ITO by electroreduction of the in situ generated parent diazonium compound. Polypyrrole (PPy) thin films exhibited remarkable adhesion to aminophenyl (ITO-AP). The strongly adherent polypyrrole films exhibited excellent electroactivity in the doped state with BSA which itself served to chelate the metal ions in aqueous medium. The surface of the resulting, modified flexible electrode was characterized by XPS, SEM, and electrochemical methods. The ITO-AP-PPy electrodes were then used for the simultaneous detection of Cu2+, Cd2+, and Pb2+ by differential pulse voltammetry (DPV). The detection limits were 11.1, 8.95, and 0.99 nM for Cu2+, Cd2+, and Pb2+, respectively. In addition, the modified electrodes displayed a good reproducibility, making them suitable for the determination of heavy metals in real wastewater samples.


Assuntos
Adesivos/química , Compostos de Diazônio/química , Metais Pesados/análise , Polímeros/química , Pirróis/química , Poluentes Químicos da Água/análise , Benzenossulfonatos/química , Técnicas Eletroquímicas , Eletrodos , Limite de Detecção , Metais Pesados/química , Reprodutibilidade dos Testes , Poluentes Químicos da Água/química
13.
Biosens Bioelectron ; 113: 32-38, 2018 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-29727749

RESUMO

We investigated an Electrolyte-Gated Organic Field-Effect transistor based on poly(N-alkyldiketopyrrolo-pyrrole dithienylthieno[3,2-b]thiophene) as organic semiconductor whose gate electrode was functionalized by electrografting a functional diazonium salt capable to bind an antibody specific to 2,4-dichlorophenoxyacetic acid (2,4-D), an herbicide well-known to be a soil and water pollutant. Molecular docking computations were performed to design the functional diazonium salt to rationalize the antibody capture on the gate surface. Sensing of 2,4-D was performed through a displacement immunoassay. The limit of detection was estimated at around 2.5 fM.


Assuntos
Ácido 2,4-Diclorofenoxiacético/análise , Técnicas Biossensoriais/instrumentação , Compostos de Diazônio/química , Herbicidas/análise , Transistores Eletrônicos , Poluentes Químicos da Água/análise , Anticorpos Imobilizados/química , Técnicas Biossensoriais/métodos , Eletrólitos/química , Desenho de Equipamento , Imunoensaio/instrumentação , Imunoensaio/métodos , Limite de Detecção , Modelos Moleculares , Água/análise
14.
Mol Imaging Biol ; 20(6): 1015-1024, 2018 12.
Artigo em Inglês | MEDLINE | ID: mdl-29736561

RESUMO

PURPOSE: There is a strong, unmet need for superior positron emission tomography (PET) imaging agents that are able to measure biochemical processes specific to prostate cancer. Pyruvate kinase M2 (PKM2) catalyzes the concluding step in glycolysis and is a key regulator of tumor growth and metabolism. Elevation of PKM2 expression was detected in Gleason 8-10 tumors compared to Gleason 6-7 carcinomas, indicating that PKM2 may potentially be a marker of aggressive prostate cancer. We have recently reported the development of a PKM2-specific radiopharmaceutical [18F]DASA-23 and herein describe its evaluation in cell culture and preclinical models of prostate cancer. PROCEDURE: The cellular uptake of [18F]DASA-23 was evaluated in a panel of prostate cancer cell lines and compared to that of [18F]FDG. The specificity of [18F]DASA-23 to measure PKM2 levels in cell culture was additionally confirmed through the use of PKM2-specific siRNA. PET imaging studies were then completed utilizing subcutaneous prostate cancer xenografts using either PC3 or DU145 cells in mice. RESULTS: [18F]DASA-23 uptake values over 60-min incubation period in PC3, LnCAP, and DU145 respectively were 23.4 ± 4.5, 18.0 ± 2.1, and 53.1 ± 4.6 % tracer/mg protein. Transient reduction in PKM2 protein expression with siRNA resulted in a 50.1 % reduction in radiotracer uptake in DU145 cells. Small animal PET imaging revealed 0.86 ± 0.13 and 1.6 ± 0.2 % ID/g at 30 min post injection of radioactivity in DU145 and PC3 subcutaneous tumor bearing mice respectively. CONCLUSION: Herein, we evaluated a F-18-labeled PKM2-specific radiotracer, [18F]DASA-23, for the molecular imaging of prostate cancer with PET. [18F]DASA-23 revealed rapid and extensive uptake levels in cellular uptake studies of prostate cancer cells; however, there was only modest tumor uptake when evaluated in mouse subcutaneous tumor models.


Assuntos
Compostos de Diazônio/química , Fluordesoxiglucose F18/química , Imagem Molecular/métodos , Tomografia por Emissão de Pósitrons/métodos , Neoplasias da Próstata/diagnóstico , Ácidos Sulfanílicos/química , Animais , Linhagem Celular Tumoral , Compostos de Diazônio/farmacocinética , Feminino , Fluordesoxiglucose F18/farmacocinética , Glicólise/fisiologia , Xenoenxertos , Humanos , Masculino , Camundongos , Camundongos Nus , Transplante de Neoplasias , Células PC-3 , Valor Preditivo dos Testes , Neoplasias da Próstata/metabolismo , Neoplasias da Próstata/patologia , Ácidos Sulfanílicos/farmacocinética
15.
Org Biomol Chem ; 16(18): 3353-3357, 2018 05 09.
Artigo em Inglês | MEDLINE | ID: mdl-29634058

RESUMO

A new bench-stable reagent with double diazonium sites was designed and synthesized for protein crosslinking. Based on the highly efficient diazonium-Tyr coupling reaction, a direct mixture of the reagent and tobacco mosaic virus led to the formation of a new hydrogel, which could be degraded by chemicals and could be used to encapsulate small molecules for sustained release. Because plant viruses exhibit many chemical characteristics like protein labelling and nucleic acid packaging, the virus-based hydrogel will have large chemical space for further functionalization. Besides, this dual-diazonium reagent should be a generally useful crosslinker for chemical biology and biomaterials.


Assuntos
Reagentes para Ligações Cruzadas/química , Preparações de Ação Retardada/química , Compostos de Diazônio/química , Hidrogéis/química , Proteínas/química , Vírus do Mosaico do Tabaco/química , Tirosina/química
16.
Talanta ; 179: 131-138, 2018 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-29310212

RESUMO

A sensitive amperometric immunosensor has been prepared by immobilization of capture antibodies onto gold nanoparticles (AuNPs) grafted on a screen-printed carbon electrode (SPCE) through aryl diazonium salt chemistry using 4-aminothiophenol (AuNPs-S-Phe-SPCE). The immunosensor was designed for the accurate determination of clinically relevant levels of B-type natriuretic peptide (BNP) in human serum samples. The nanostructured electrochemical platform resulted in an ordered layer of AuNPs onto SPCEs which combined the advantages of high conductivity and improved stability of immobilized biomolecules. The resulting disposable immunosensor used a sandwich type immunoassay involving a peroxidase-labeled detector antibody. The amperometric transduction was carried out at -0.20V (vs the Ag pseudo-reference electrode) upon the addition of hydroquinone (HQ) as electron transfer mediator and H2O2 as the enzyme substrate. The nanostructured immunosensors show a storage stability of at least 25 days, a linear range between 0.014 and 15ngmL-1, and a LOD of 4pgmL-1, which is 100 times lower than the established cut-off value for heart failure (HF) diagnosis. The performance of the immunosensor is advantageously compared with that provided with immunosensors prepared by grafting SPCE with p-phenylendiamine (H2N-Phe-SPCE) and attaching AuNPs by immersion into an AuNPs suspension or by electrochemical deposition, as well as with immunosensors constructed using commercial AuNPs-modified SPCEs. The developed immunosensor was applied to the successful analysis of human serum from heart failure (HF) patients upon just a 10-times dilution as sample treatment.


Assuntos
Técnicas Biossensoriais , Técnicas Eletroquímicas , Insuficiência Cardíaca/diagnóstico , Imunoensaio , Nanopartículas Metálicas/química , Peptídeo Natriurético Encefálico/sangue , Compostos de Anilina/química , Anticorpos/química , Biomarcadores/sangue , Carbono/química , Compostos de Diazônio/química , Eletrodos , Ouro/química , Insuficiência Cardíaca/sangue , Humanos , Peróxido de Hidrogênio/química , Hidroquinonas/química , Imunoconjugados/química , Nanopartículas Metálicas/ultraestrutura , Nanoestruturas/química , Nanoestruturas/ultraestrutura , Peroxidase/química , Compostos de Sulfidrila/química
17.
Artigo em Inglês | MEDLINE | ID: mdl-28982066

RESUMO

Ti6Al4V alloy is the most commonly used in orthopedic industry as an endoprosthesis. Ti6Al4V exhibits good mechanical properties, except the abrasion resistance. Surface modification of Ti6Al4V in order to obtain organic layer, and then the attachment of the polymer, can allow for overcoming this problem. The aim of the work was the modification of Ti6Al4V surface by diazonium compounds: salt or cation generated in situ and examine the influence of the reducing agent - ascorbic acid, and the temperature of reaction on modification process. Moreover, the simulated body fluid was used for the assessment of the organic layer stability on Ti6Al4V surface. The evaluation of the modification was carried out using the following methods: Raman microspectroscopy, scanning electron microscopy and energy-dispersive X-ray spectroscopy. Higher temperature of modification by 4-hydroxymethylbenzenediazonium cation, provides the largest amount of organic layer on the Ti6Al4V alloy. In the case of the Ti6Al4V modified by Variamine Blue B salt, the amount of organic layer is not dependent on the reaction condition. Moreover, the ascorbic acid and the presence of TiO2 does not effect on the modification. The modified surface is completely coated with the organic layer which is stable in simulated body fluid.


Assuntos
Compostos de Diazônio/química , Titânio/química , Líquidos Corporais/química , Processamento de Imagem Assistida por Computador , Óxidos/química , Espectrometria de Fluorescência , Análise Espectral Raman , Propriedades de Superfície , Temperatura Ambiente
18.
Anal Chem ; 90(3): 2201-2209, 2018 02 06.
Artigo em Inglês | MEDLINE | ID: mdl-29285924

RESUMO

We report the unique self-catalyzing chemiluminescence (CL) of luminol-diazonium ion (N2+-luminol) and its analytical potential. Visual CL emission was initially observed when N2+-luminol was subjected to alkaline aqueous H2O2 without the aid of any catalysts. Further experimental investigations found peroxidase-like activity of N2+-luminol on the cleavage of H2O2 into OH• radical. Together with other experimental evidence, the CL mechanism is suggested as the activation of N2+-luminol and its dediazotization product 3-hydroxyl luminol by OH• radical into corresponding intermediate radicals, and then further oxidation to excited-state 3-N2+-phthalic acid and 3-hydroxyphthalic acid, which finally produce 415 nm CL. The self-catalyzing CL of N2+-luminol provides us an opportunity to achieve the attractive catalyst-free CL detection of H2O2. Experiments demonstrated the 10-8 M level detection sensitivity to H2O2 as well as to glucose or uric acid if presubjected to glucose oxidase or uricase. With the exampled determination of serum glucose and uric acid, N2+-luminol shows its analytical potential for other analytes linking the production or consumption of H2O2. Under physiological condition, N2+-luminol exhibits highly selective and sensitive CL toward 1O2 among the common reactive oxygen species. This capacity supports the significant application of N2+-luminol for detecting 1O2 in live animals. By imaging the arthritis in LEW rats, N2+-luminol CL is demonstrated as a potential tool for mapping the inflammation-relevant biological events in a live body.


Assuntos
Artrite/diagnóstico , Compostos de Diazônio/química , Peróxido de Hidrogênio/análise , Substâncias Luminescentes/química , Luminol/análogos & derivados , Luminol/química , Animais , Catálise , Feminino , Glucose/análise , Limite de Detecção , Imagem Óptica/métodos , Ratos Endogâmicos Lew , Ácido Úrico/análise
19.
Dent Mater ; 33(11): e393-e404, 2017 11.
Artigo em Inglês | MEDLINE | ID: mdl-28797747

RESUMO

OBJECTIVE: Composite resins do not adhere well to dental alloys. This weak bond can result in failure at the composite-metal interface in fixed dental prostheses and orthodontic brackets. The aim of this study was to develop a new adhesive, based on diazonium chemistry, to facilitate chemical bonding between dental alloys and composite resin. METHODS: Samples of two types of dental alloys, stainless steel and cobalt chromium were primed with a diazonium layer in order to create a surface coating favorable for composite adhesion. Untreated metal samples served as controls. The surface chemical composition of the treated and untreated samples was analyzed by X-ray photoelectron spectroscopy (XPS) and the tensile strength of the bond with composite resin was measured. The diazonium adhesive was also tested for shear bond strength between stainless steel orthodontic brackets and teeth. RESULTS: XPS confirmed the presence of a diazonium coating on the treated metals. The coating significantly increased the tensile and shear bond strengths by three and four folds respectively between the treated alloys and composite resin. CONCLUSION: diazonium chemistry can be used to develop composite adhesives for dental alloys. SIGNIFICANCE: Diazonium adhesion can effectively achieve a strong chemical bond between dental alloys and composite resin. This technology can be used for composite repair of fractured crowns, for crown cementation with resin based cements, and for bracket bonding.


Assuntos
Resinas Compostas/química , Ligas Dentárias/química , Colagem Dentária , Compostos de Diazônio/química , Braquetes Ortodônticos , Adesividade , Bis-Fenol A-Glicidil Metacrilato , Materiais Dentários/química , Teste de Materiais , Espectroscopia Fotoeletrônica , Polietilenoglicóis , Ácidos Polimetacrílicos , Cimentos de Resina , Propriedades de Superfície
20.
Angew Chem Int Ed Engl ; 56(42): 12866-12872, 2017 10 09.
Artigo em Inglês | MEDLINE | ID: mdl-28815832

RESUMO

The exploitation of synthetic lethality by small-molecule targeting of pathways that maintain genomic stability is an attractive chemotherapeutic approach. The Ctf4/AND-1 protein hub, which links DNA replication, repair, and chromosome segregation, represents a novel target for the synthetic lethality approach. Herein, we report the design, optimization, and validation of double-click stapled peptides encoding the Ctf4-interacting peptide (CIP) of the replicative helicase subunit Sld5. By screening stapling positions in the Sld5 CIP, we identified an unorthodox i,i+6 stapled peptide with improved, submicromolar binding to Ctf4. The mode of interaction with Ctf4 was confirmed by a crystal structure of the stapled Sld5 peptide bound to Ctf4. The stapled Sld5 peptide was able to displace the Ctf4 partner DNA polymerase α from the replisome in yeast extracts. Our study provides proof-of-principle evidence for the development of small-molecule inhibitors of the human CTF4 orthologue AND-1.


Assuntos
Peptídeos/metabolismo , Motivos de Aminoácidos , Sítios de Ligação , Cristalografia por Raios X , DNA Polimerase I/química , DNA Polimerase I/metabolismo , Proteínas de Ligação a DNA/química , Proteínas de Ligação a DNA/metabolismo , Compostos de Diazônio/química , Polarização de Fluorescência , Instabilidade Genômica , Humanos , Simulação de Dinâmica Molecular , Peptídeos/síntese química , Peptídeos/química , Domínios e Motivos de Interação entre Proteínas , Estrutura Terciária de Proteína , Saccharomyces cerevisiae/metabolismo , Proteínas de Saccharomyces cerevisiae/metabolismo
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