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1.
J Autoimmun ; : 102463, 2020 Apr 13.
Artigo em Inglês | MEDLINE | ID: mdl-32303424

RESUMO

It has been reported that SARS-CoV-2 may use ACE2 as a receptor to gain entry into human cells, in a way similar to that of SARS-CoV. Analyzing the distribution and expression level of ACE2 may therefore help reveal underlying mechanisms of viral susceptibility and post-infection modulation. In this study, we utilized previously uploaded information on ACE2 expression in various conditions including SARS-CoA to evaluate the role of ACE2 in SARS-CoV and extrapolate that to COVID-19. We found that the expression of ACE2 in healthy populations and patients with underlying diseases was not significantly different. However, based on the elevated expression of ACE2 in cigarette smokers, we speculate that long-term smoking may be a risk factor for COVID-19. Analysis of ACE2 in SARS-CoV infected cells suggests that ACE2 is not only a receptor but is also involved in post-infection regulation, including immune response, cytokine secretion, and viral genome replication. Moreover, we constructed Protein-protein interaction (PPI) networks and identified hub genes in viral activity and cytokine secretion. Our findings may help clinicians and researchers gain more insight into the pathogenesis of SARS-CoV-2 and design therapeutic strategies for COVID-19.

2.
J Biochem Mol Toxicol ; 34(2): e22429, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31860774

RESUMO

Alzheimer's disease (AD) is an age-associated neurodegenerative disease, which is developed by oxidative stress and acetylcholine contraction in the synaptic cleft of the neurons. This leads to dementia, memory loss, and decrease in learning ability and orientation. In this research work, we aimed to explore the neuroprotective effect of neferine on AlCl3 -induced AD in rats. The results of our study revealed that the increased reactive oxygen species (ROS) and nitric oxide in the hippocampus leads to the development of AD in the rats. The oral treatment of neferine done the following occurrences such as; it potentially inhibited the ROS formation and acts as a scavenging molecule by preventing the neurodegeneration. It also improved the memory and learning ability to complete the maze activity in the AD rats and significantly increased the antioxidants superoxide dismutase, catalase, and reduced glutathione in neferine treated AD rats. It aggressively declined the activity of acetylcholine esterase and Na+ K+ ATPase in the neurodegenerative rat models. The gene expression pattern of neuroinflammatory cytokines such as tumor necrosis factor α (TNF-α), interleukin-6 (IL-6), and interleukin-1ß (IL-1ß) were decreased in the neferine-treated rats. The neuroinflammatory proteins such as inducible nitric oxide (iNOS), cyclooxygenase-2 (COX-2), and nuclear factor kappa ß (Nf-κß) were decreased and Nf-κß inhibitor IKBα was increased in the neferine-treated AD rats. Finally, the histology study proved that the neferine treatment possibly prevents neurodegeneration in the hippocampus tissue of the AD models. Hence, these all findings concluded that the neferine could be a potential neuropreventive as well as neurodegenerative therapeutic compound in neurological and cognitive dysfunction.


Assuntos
Cloreto de Alumínio/farmacologia , Doença de Alzheimer/induzido quimicamente , Doença de Alzheimer/tratamento farmacológico , Benzilisoquinolinas/farmacologia , Medicamentos de Ervas Chinesas/farmacologia , Fármacos Neuroprotetores/farmacologia , Nootrópicos/farmacologia , Administração Oral , Cloreto de Alumínio/efeitos adversos , Animais , Comportamento Animal/efeitos dos fármacos , Benzilisoquinolinas/administração & dosagem , Ciclo-Oxigenase 2/metabolismo , Citocinas/genética , Modelos Animais de Doenças , Medicamentos de Ervas Chinesas/administração & dosagem , Feminino , Expressão Gênica/efeitos dos fármacos , Hipocampo/metabolismo , Hipocampo/patologia , Peroxidação de Lipídeos/efeitos dos fármacos , Masculino , Aprendizagem em Labirinto/efeitos dos fármacos , NF-kappa B/metabolismo , Fármacos Neuroprotetores/administração & dosagem , Óxido Nítrico Sintase Tipo II/metabolismo , Nootrópicos/administração & dosagem , Estresse Oxidativo/efeitos dos fármacos , Ratos , Ratos Wistar
3.
EBioMedicine ; 33: 242-252, 2018 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-29997053

RESUMO

Mucus secretion accumulation in the airways may act as a contributing factor for the development of airflow limitation in severe fetal asthma patients. Accumulated evidences showed that transforming growth factor beta (TGF-ß) plays a regulatory role in airway remodeling including mucus hyper-secretion in asthma. However, the detailed molecular mechanisms of TGF-ß3 induced MUC5AC hyper-expression in airway epithelium remains unclear. Here, we demonstrated the pivotal roles of autophagy in regulation of MUC5AC hyper-production induced by TGF-ß3 in airway epithelium. Our experimental data showed that inhibiting autophagy pathway in repeated ovalbumin (OVA) exposed mice exhibited decreased airway hyper-response and airway inflammation, diminishing the expression of Muc5ac and TGF-ß3. Furthermore, our studies demonstrated that autophagy was induced upon exposure to TGF-ß3 and then mediated MUC5AC hyper-expression by activating the activator protein-1 (AP-1) in human bronchial epithelial cells. Finally, Smad2/3 pathway was involved in TGF-ß3-induced MUC5AC hyper-expressions by promoting autophagy. These data indicated that autophagy was required for TGF-ß3 induced airway mucous hyper-production, and that inhibition of autophagy exerted therapeutic benefits for TGF-ß3 induced airway mucus secretion.


Assuntos
Asma/metabolismo , Brônquios/citologia , Mucina-5AC/metabolismo , Ovalbumina/efeitos adversos , Fator de Crescimento Transformador beta3/metabolismo , Regulação para Cima , Animais , Asma/induzido quimicamente , Autofagia , Brônquios/metabolismo , Modelos Animais de Doenças , Células Epiteliais/citologia , Feminino , Humanos , Camundongos , Transdução de Sinais , Fator de Transcrição AP-1/metabolismo
4.
Technol Cancer Res Treat ; 17: 1533034618756783, 2018 01 01.
Artigo em Inglês | MEDLINE | ID: mdl-29444619

RESUMO

HOX transcript antisense intergenic RNA has been reported to serve as an important prognostic biomarker in several types of cancers. However, the clinical value of HOX transcript antisense intergenic RNA in digestive cancers remains unclear. Therefore, we tried to investigate the clinical role of expression of HOX transcript antisense intergenic RNA as a prognostic indicator in digestive cancers by a meta-analysis. Literature collection was performed by searching the PubMed, Embase, Web of Science, and Cochrane Library databases (up to October 7, 2017). A quantitative meta-analysis was conducted to assess the eligible articles on the prognostic value of HOX transcript antisense intergenic RNA in digestive cancers. The pooled hazard ratios or odds ratios with 95% confidence intervals were used to evaluate the association between expression of HOX transcript antisense intergenic RNA and clinical outcomes. A total of 1844 patients from 22 studies were included in this meta-analysis. The results found a significant association between expression of HOX transcript antisense intergenic RNA and poor overall survival in digestive cancers (pooled hazard ratio = 2.19, 95% confidence interval, 1.86-2.57, P < .001). Furthermore, subgroup analysis showed that tumor type, region, Newcastle-Ottawa scale, and sample size did not alter the predictive value of HOX transcript antisense intergenic RNA as an independent factor for patients' survival. In addition, we also revealed that the clinicopathological characteristics such as differentiation, lymph node metastasis, tumor node metastasis (TNM) stage, and distant metastasis were positively related to expression of HOX transcript antisense intergenic RNA digestive cancers. In conclusion, our results suggested high expression of HOX transcript antisense intergenic RNA was correlated with poor clinical outcomes and may serve as a novel prognostic biomarker for patients with digestive cancers.


Assuntos
Biomarcadores Tumorais , Neoplasias do Sistema Digestório/genética , RNA Longo não Codificante/genética , Neoplasias do Sistema Digestório/diagnóstico , Neoplasias do Sistema Digestório/mortalidade , Regulação Neoplásica da Expressão Gênica , Estudos de Associação Genética , Predisposição Genética para Doença , Humanos , Gradação de Tumores , Estadiamento de Neoplasias , Razão de Chances , Prognóstico , Modelos de Riscos Proporcionais , Viés de Publicação , Curva ROC , Análise de Sobrevida
5.
Artigo em Inglês | MEDLINE | ID: mdl-29335367

RESUMO

Mammalian species differ dramatically in telomere biology. Species larger than 5-10 kg repress somatic telomerase activity and have shorter telomeres, leading to replicative senescence. It has been proposed that evolution of replicative senescence in large-bodied species is an anti-tumour mechanism counteracting increased risk of cancer due to increased cell numbers. By contrast, small-bodied species express high telomerase activity and have longer telomeres. To counteract cancer risk due to longer lifespan, long-lived small-bodied species evolved additional telomere-independent tumour suppressor mechanisms. Here, we tested the connection between telomere biology and tumorigenesis by analysing the propensity of fibroblasts from 18 rodent species to form tumours. We found a negative correlation between species lifespan and anchorage-independent growth. Small-bodied species required inactivation of Rb and/or p53 and expression of oncogenic H-Ras to form tumours. Large-bodied species displayed a continuum of phenotypes requiring additional genetic 'hits' for malignant transformation. Based on these data we refine the model of the evolution of tumour suppressor mechanisms and telomeres. We propose that two different strategies evolved in small and large species because small-bodied species cannot tolerate small tumours that form prior to activation of the telomere barrier, and must instead use telomere-independent strategies that act earlier, at the hyperplasia stage.This article is part of the theme issue 'Understanding diversity in telomere dynamics'.


Assuntos
Carcinogênese/genética , Evolução Molecular , Roedores/genética , Homeostase do Telômero , Telômero/metabolismo , Animais , Senescência Celular/genética , Fibroblastos/citologia , Genes do Retinoblastoma/genética , Genes p53/genética , Genes ras/genética , Humanos , Camundongos Nus , Cultura Primária de Células , Pele/citologia , Telomerase/metabolismo , Ensaios Antitumorais Modelo de Xenoenxerto
6.
Xi Bao Yu Fen Zi Mian Yi Xue Za Zhi ; 33(4): 488-491, 2017 Apr.
Artigo em Chinês | MEDLINE | ID: mdl-28395719

RESUMO

Objective To study the effect of alphacalcidol and dexamethasone on pulmonary fibrosis and its mechanism. Methods Forty C57BL/6 mice were randomly divided into five groups: normal control group, pulmonary fibrosis group, alphacalcidol group, dexamethasone group, dexamethasone combined with alphacalcidol group. The normal control group was given 0.5 µL/g normal saline by one-time intratracheal injection as well as 0.2 mL normal saline by daily intragastric infusion. The other groups received 0.5 µL/g bleomycin solution by one-time intratracheal injection; besides, the pulmonary fibrosis group were subjected to 0.2 mL normal saline gavage; the dexamethasone group were treated with dexamethasone [0.5 mg/ (kg.d)] orally; the alphacalcidol group received intragastric infusion of alphacalcidol [0.5 µg/ (kg.d)]; and the dexamethasone plus alphacalcidol group was given dexamethasone [0.5 mg/ (kg.d)] mixed with alphacalcidol [0.5 µg/ (kg.d)] orally. Then they were killed after 21 days. The pathological changes of lung tissues was observed using HE and Masson staining. The serum was collected to detect hydroxyproline (Hyp) values. Bronchoalveolar lavage fluid (BALF) was collected for cell counting. ELISA was performed to examine interleukin 1 beta (IL-1ß), IL-6, tumor necrosis factor alpha (TNF-α) and transforming growth factor beta 1 (TGF-ß1) in supernatants. Results In the alphacalcidol combined with dexamethasone group, IL-1ß, IL-6, TNF-α and TGF-ß1, cell count, Sazpiel score, Hyp values were lower than those in the other groups except for the control group, and the alveolar inflammation and fibrin deposition were also lower than those in the other groups except for the control group. Conclusion The curative effect of alphacalcidol combined with dexamethasone on pulmonary fibrosis is better than either dexamethasone or alphacalcidol alone, and the mechanism may be related to the inhibition of TGF-ß1 and inflammatory factors.


Assuntos
Dexametasona/administração & dosagem , Hidroxicolecalciferóis/administração & dosagem , Fibrose Pulmonar/tratamento farmacológico , Animais , Modelos Animais de Doenças , Quimioterapia Combinada , Humanos , Interleucina-6/genética , Interleucina-6/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Fibrose Pulmonar/genética , Fibrose Pulmonar/metabolismo , Fator de Crescimento Transformador beta1/genética , Fator de Crescimento Transformador beta1/metabolismo , Fator de Necrose Tumoral alfa/genética , Fator de Necrose Tumoral alfa/metabolismo
7.
Oncotarget ; 8(68): 113174-113184, 2017 Dec 22.
Artigo em Inglês | MEDLINE | ID: mdl-29348896

RESUMO

Background: Plasmacytoma variant translocation 1 (PVT1) has recently been reported to be aberrantly expressed and serves as a prognostic biomarker in many types of cancers. However, its prognostic significance remains controversial. Here, we conducted a meta-analysis to investigate the prognostic value of PVT1 expression in cancers. Results: A total of 2109 patients from 20 studies were included. The results showed that elevated PVT1 expression predicted a poor outcome for overall survival (OS) in nine types of cancers (HR = 1.40, 95% CI: 1.21-1.59). Subgroup analysis indicated that there was a significant association between PVT1 overexpression and poor OS of patients with gastric cancer, gynecology cancer and lung cancer. Furthermore, we also found a negative significant relationship between PVT1 expression and disease-free survival (HR = 1.83, 95% CI: 1.39-2.27), progression-free survival (HR = 1.63, 95% CI: 1.34-1.93) and recurrence-free survival (HR = 1.74, 95% CI: 1.01-2.47). In addition, the level of PVT1 expression was positively related to tumor size, TNM stage, lymph node metastasis and distant metastases. Materials and Methods: A systematic search was performed through the PubMed, EMBASE, Web of Science, Ovid and Cochrane library databases for eligible studies on prognostic value of PVT1 in cancers from inception up to June, 2017. The pooled hazard ratios (HRs) or odds ratios (ORs) with 95% confidence intervals (CIs) were used to evaluate the association between PVT1 expression and clinical outcomes. Conclusions: PVT1 expression positively related to tumor size, TNM stages, lymph node metastasis and distant metastases, and served as a prognostic biomarker in different types of cancers.

8.
Sci Rep ; 6: 29751, 2016 07 19.
Artigo em Inglês | MEDLINE | ID: mdl-27432148

RESUMO

Prevalence of atopic dermatitis (AD) is increasing worldwide. Up to date, there has been no face-to-face nation-wide study in China. We aim to explore the prevalence of clinical diagnosed AD in children aged 1-7 ys in China. Twelve metropolises were chosen from different areas of China. In each region, we selected 4-10 kindergartens and 2-5 vaccination clinics randomly. A complete history-taking and skin examination were performed by dermatologists. The definite diagnosis of AD and the severity were determined by two or three dermatologists. All criteria concerned in UK diagnosis criteria, characteristic presentation of AD and atypical manifestations were recorded in detail. A total of 13998 children from 84 kindergartens and 40 vaccination clinics were included. The prevalence of AD was 12.94% by clinical diagnosis of dermatologists overall, with 74.6% of mild AD. Comparatively, prevalence of AD based on UK diagnostic criteria was 4.76%. This is the first face-to-face nation-wide study in Chinese children aged 1-7 ys, revealing that the prevalence of AD in children is closer to that of wealthier nations.


Assuntos
Dermatite Atópica/diagnóstico , Dermatite Atópica/epidemiologia , Pele/patologia , Grupo com Ancestrais do Continente Asiático , Criança , Pré-Escolar , China/epidemiologia , Dermatite Atópica/etnologia , Feminino , Geografia , Humanos , Lactente , Masculino , Prevalência , Fatores de Risco , Inquéritos e Questionários
9.
Appl Biochem Biotechnol ; 175(2): 1221-33, 2015 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-25377248

RESUMO

Eucommia leaf contains large amounts of natural active products. In extracting the substances, the most important is the removal of the cuticle layer on the leaves and the cell wall in the leaves of Eucommia ulmoides. But the removal of the cuticle layer is a technical difficulty now. Cutinase (EC3.1.1.74) is a multifunctional enzyme with a common alpha/beta fold structure belonging to hydroplane that can make a substantial degradation of horny fatty acids. So this study isolated bacteria capable of producing cutinase from the lesion of Eucommia leaves and identified the bacteria. The identification using PCR-RFLP method confirmed that the strain belongs to Rhodotorula mucilaginosa. The fermentation conditions of the strain-producing cutinase were optimized in this study. The finding of cutinase-producing R. mucilaginosa is significant because the yeast is more secure than plant pathogens, being suitable for mass production.


Assuntos
Hidrolases de Éster Carboxílico/biossíntese , Hidrolases de Éster Carboxílico/metabolismo , Rhodotorula/crescimento & desenvolvimento , Rhodotorula/isolamento & purificação , Carbono/metabolismo , Técnicas de Cultura , Eucommiaceae/microbiologia , Fermentação , Concentração de Íons de Hidrogênio , Nitrogênio/metabolismo , Folhas de Planta/microbiologia , Rhodotorula/metabolismo , Temperatura , Fatores de Tempo
10.
Bioanalysis ; 3(17): 1923-33, 2011 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-21899502

RESUMO

BACKGROUND: In early drug-discovery research, understanding the tissue distribution of drug at the site of action can help to predict the toxicity, efficacy and exposure level of the drug. The bottleneck of tissue analysis by LC-MS/MS is the time-consuming homogenization step. RESULTS: Both mechanical and enzymatic techniques for mouse tissue homogenization were evaluated, which included bead beater, polytron and enzymatic digestion. Brain, bone marrow, kidney, spleen and liver tissues can be homogenized effectively using the bead beater alone. Lung and heart tissues were best treated with collagenase first and then homogenized by the bead beater. CONCLUSION: Homogenization conditions for seven mouse tissues have been evaluated and optimized. These findings will expedite the preparation of tissue samples for analysis.


Assuntos
Cromatografia Líquida/instrumentação , Cromatografia Líquida/métodos , Descoberta de Drogas , Espectrometria de Massas em Tandem/instrumentação , Espectrometria de Massas em Tandem/métodos , Extratos de Tecidos/análise , Animais , Feminino , Camundongos , Estrutura Molecular , Tamanho da Partícula , Pirazóis/química , Pirazóis/farmacocinética , Piridazinas/química , Piridazinas/farmacocinética , Distribuição Tecidual
11.
Anal Chim Acta ; 697(1-2): 27-31, 2011 Jul 04.
Artigo em Inglês | MEDLINE | ID: mdl-21641415

RESUMO

In this paper, a simple two-step approach for redox protein immobilization was introduced. Firstly, alkynyl-terminated film was formed on electrode surface by electrochemical reduction of 4-ethylnylphenyl (4-EP) diazonium compound. Then, horseradish peroxidase (HRP) modified with azido group was covalently immobilized onto the electrografted film via click reaction. Reflection absorption infrared (RAIR) spectroscopy and electrochemical methods were used to characterize the modification process. The results indicate that HRP retains its native structure and shows fast direct electron transfer. Moreover, the immobilized HRP shows excellent electrocatalytic reduction activity toward H(2)O(2) with a linear range of 5.0×10(-6) to 9.3×10(-4) mol L(-1).


Assuntos
Química Click , Compostos de Diazônio/química , Eletroquímica/métodos , Enzimas Imobilizadas/química , Peroxidase do Rábano Silvestre/química , Adsorção , Biocatálise , Eletrodos , Transporte de Elétrons , Enzimas Imobilizadas/metabolismo , Ouro/química , Peroxidase do Rábano Silvestre/metabolismo , Peróxido de Hidrogênio/análise , Peróxido de Hidrogênio/metabolismo , Modelos Moleculares , Conformação Proteica
12.
Langmuir ; 27(6): 2910-6, 2011 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-21299195

RESUMO

A simple and versatile method for the introduction of redox unites onto the surface of magnetic nanoparticles has been developed based on "click" chemistry. Azide-functionalized Fe2O3 magnetic nanoparticles were synthesized and further reacted with ethynylferrocene via Cu(I)-catalyzed azide alkyne 1,3-dipolar cycloaddition (CuAAC) reaction. The functionalized magnetic nanoparticles were characterized using a powder X-ray diffractometer (XRD), transmission electron microscope (TEM), Fourier transform infrared spectroscope (FTIR), and vibrating sample magnetometer (VSM). The resulting materials have properties of both magnetism and electrochemistry, and the electrochemical properties of the nanoparticles are dependent on the features of ethynylferrocene, while the magnetic properties remain independent of ethynylferrocene. Because of the magnetism of Fe2O3 nanoparticles and the electrocatalytic activity of ferrocene unites, a recyclable, magneto-switchable bioelectrocatalytic system for glucose oxidation in the presence of glucose oxidase is developed by alternate positioning of an external magnet, and the system has a linear response for glucose biosensing over the range of 1.0-10.0 mM.


Assuntos
Técnicas Biossensoriais , Compostos Férricos/metabolismo , Compostos Ferrosos/metabolismo , Glucose Oxidase/metabolismo , Glucose/análise , Nanopartículas de Magnetita/química , Biocatálise , Química Click , Compostos Férricos/síntese química , Compostos Férricos/química , Compostos Ferrosos/química , Glucose/metabolismo , Glucose Oxidase/química , Fenômenos Magnéticos , Metalocenos , Oxirredução , Propriedades de Superfície
13.
Talanta ; 83(5): 1381-5, 2011 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-21238725

RESUMO

A simple and versatile approach for covalent immobilization of redox protein on solid surface via self-assembled technique and click chemistry is reported. The alkynyl-terminated monolayers are obtained by self-assembled technique, then, azido-horseradish peroxidase (azido-HRP) was covalent immobilized onto the formed monolayers by click reaction. The modified process is characterized by reflection absorption infrared spectroscopy (RAIR), surface-enhanced Raman scattering spectroscopy (SERS) and electrochemical methods. All the experimental results suggest that HRP is immobilized onto the electrode surface successfully without denaturation. Furthermore, the immobilized HRP shows electrocatalytic reduction for H(2)O(2), and the linear range is from 5.0 to 700 µM. The heterogeneous electron transfer rate constant k(s) is 1.11 s(-1) and the apparent Michaelis-Menten constant is calculated to be 0.196 mM.


Assuntos
Enzimas Imobilizadas/química , Peroxidase do Rábano Silvestre/química , Técnicas Biossensoriais/tendências , Eletroquímica , Espectroscopia de Luz Próxima ao Infravermelho
14.
Phys Chem Chem Phys ; 12(40): 13287-95, 2010 Oct 28.
Artigo em Inglês | MEDLINE | ID: mdl-20830428

RESUMO

In this paper, catechol, 1,4-dihydroxybenzene and dopamine are investigated as precursors of electrophiles for Michael addition reaction with the self-assembled monolayer (SAM) of 4-thiouracil (4-TU) via electrochemical triggering. All compounds can undergo Michael addition reaction with 4-TU; however, only catechol can react with 4-TU with high efficiency. The catechol-terminated SAMs, via electrochemically triggered Michael addition reaction, exhibit reversible redox response. In addition, we find that catechol-terminated SAMs can complex with Ni(2+) and Cu(2+) with different electrochemical behaviors. Moreover, the mechanism of complexation of Ni(2+)and Cu(2+) with catechol-terminated SAMs is also demonstrated with electrochemical and spectrometric methods. Based on the different electrochemical behaviors of Cu(2+) and Ni(2+) complex, the catechol-terminated SAMs provide a potential platform for metal ions recognition.

15.
J Colloid Interface Sci ; 350(2): 544-50, 2010 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-20678775

RESUMO

In this paper, a simple, facile and general strategy was proposed for the covalent biofunctionalization of Au surface with hemoglobin (Hb). Structurally well-defined azide-terminated organic self-assembled monolayers (SAMs) were formed on Au surface from a mixture solution of azidoundecanethiol and dilute thiol. 4-Pentynoic acid was used as a bifunctional linker to immobilized Hb via a selective, reliable, robust click reaction and a widely used carbodiimide reaction. The surface modification was characterized by reflectance absorption infrared (RAIR) spectroscopy, electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). The experimental data indicate that the proposed methodology is a highly versatile strategy for quantitative, stable and covalent attachment of biomacromolecules onto solid interface. The Hb functionalized Au electrode shows a pair of well-defined and quasi-reversible peaks at about -0.210 V (vs. SCE) in 0.1 mol/L pH 5.0 buffers, which stands for the reduction and oxidation of Hb Fe(III)/Fe(II) redox couple. The electron transfer rate constant (k(s)) was estimated to be 0.78 s(-1). The maximal surface coverage (Gamma) of the immobilized Hb was 8.3 x 10(-12) mol cm(-2), indicating the formation of a monolayer. Moreover, the biocatalytic activity of the Hb biofunctonalized electrode was investigated and an excellent electrocatalytic reduction toward O(2) and H(2)O(2) was observed.


Assuntos
Carbodi-Imidas/química , Ouro/química , Hemoglobinas/química , Biocatálise , Transporte de Elétrons , Microscopia de Força Atômica , Modelos Biológicos , Estrutura Molecular , Oxirredução , Propriedades de Superfície
16.
Talanta ; 82(4): 1511-5, 2010 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-20801365

RESUMO

A highly soluble poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonic acid)/Au (PEDOT-PSS/Au) nanocomposite was prepared via one-step chemical synthesis and the matrix was characterized by UV-vis spectroscopy (UV-vis), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscope (SEM) and transmission electron microscope (TEM). Due to the excellent aqueous compatibility and biocompatibility, the PEDOT/PSS-Au nanocomposite can be used as biomaterial for enzymes immobilization. In this system, redox enzyme, horseradish peroxidase (HRP) was integrated with PEDOT/PSS-Au nanocomposite and the direct electron transfer of HRP was observed. Moreover, we find that the HRP/PEDOT-PSS/Au modified electrode shows excellent electrocatalytic ability for H(2)O(2) and the formal Michaelis-Menten constant (K(m)(app)) was 0.78 mmol/L. The response currents have good linear relation with the concentrations of H(2)O(2) with a linear range from 2.0 x 10(-7) to 3.8 x 10(-4)mol/L.


Assuntos
Técnicas Biossensoriais , Enzimas Imobilizadas/metabolismo , Ouro , Peroxidase do Rábano Silvestre/metabolismo , Nanocompostos , Poliestirenos/química , Tiofenos/química , Microscopia Eletrônica de Varredura , Microscopia Eletrônica de Transmissão , Solubilidade , Espectrofotometria Ultravioleta
17.
Chemphyschem ; 10(17): 3105-11, 2009 Dec 07.
Artigo em Inglês | MEDLINE | ID: mdl-19834930

RESUMO

Herein, we report a versatile surface chemistry methodology to covalently immobilize ligands and proteins to self-assembled monolayers (SAMs) on gold electrode. The strategy is based on two steps: 1) the coupling of soluble azido-PEG-amimo ligand with an alkynyl-terminated monolayer via click reaction and 2) covalent immobilization hemoglobin (Hb) to the amine-terminated ligand via carbodiimide reaction. Surface-enhanced Raman scattering spectroscopy (SERS), atomic force microscopy (AFM), reflection absorption infrared spectroscopy (RAIR) and cyclic voltammetry are used to characterize the model interfacial reactions. We also demonstrate the excellent biocompatibility of the interface for Hb immobilization and reliable application of the proposed method for H(2)O(2) biosensing. Moreover, the redox thermodynamics of the Fe(3+)/Fe(2+) couple in Hb is also investigated.


Assuntos
Eletrodos , Ouro , Hemoglobinas/química , Técnicas Biossensoriais/métodos , Catálise , Técnicas Eletroquímicas , Peróxido de Hidrogênio/análise , Ferro/química , Oxirredução , Termodinâmica
18.
Rev Sci Instrum ; 78(10): 104104, 2007 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-17979439

RESUMO

We describe an advanced and highly sensitive instrument for quantum state-resolved molecule-surface energy transfer studies under ultrahigh vacuum (UHV) conditions. The apparatus includes a beam source chamber, two differential pumping chambers, and a UHV chamber for surface preparation, surface characterization, and molecular beam scattering. Pulsed and collimated supersonic molecular beams are generated by expanding target molecule mixtures through a home-built pulsed nozzle, and excited quantum state-selected molecules were prepared via tunable, narrow-band laser overtone pumping. Detection systems have been designed to measure specific vibrational-rotational state, time-of-flight, angular and velocity distributions of molecular beams coming to and scattered off the surface. Facilities are provided to clean and characterize the surface under UHV conditions. Initial experiments on the scattering of HCl(v = 0) from Au(111) show many advantages of this new instrument for fundamental studies of the energy transfer at the gas-surface interface.


Assuntos
Transferência de Energia , Gases/química , Técnicas de Sonda Molecular/instrumentação , Fotometria/instrumentação , Radiometria/instrumentação , Análise Espectral/instrumentação , Desenho de Equipamento , Análise de Falha de Equipamento , Fotometria/métodos , Doses de Radiação , Radiometria/métodos , Reprodutibilidade dos Testes , Espalhamento de Radiação , Sensibilidade e Especificidade , Análise Espectral/métodos
19.
J Chem Phys ; 122(4): 44307, 2005 Jan 22.
Artigo em Inglês | MEDLINE | ID: mdl-15740248

RESUMO

The dynamics of the F atom reaction with propyne (CH(3)CCH) has been investigated using a universal crossed molecular beam apparatus. Two reaction channels have been clearly observed: H+C(3)H(3)F and HF+C(3)H(3). The substitution of F for H occurs mainly via a complex formation mechanism, producing reaction products with some contribution from a direct reaction mechanism. The HF product, however, appears to be dominantly forward scattered relative to the F atom beam direction, suggesting that the HF formation occurs via a direct abstraction mechanism. Branching ratios for the two observed reaction channels are also determined. The H formation channel is found to be the major reaction pathway, while the HF formation channel is also significant. From the measurements of DF versus HF products from the F atom reaction with deuterated propyne, the H atom picked up by the F atom in the reaction with normal propyne seems to come mostly from the CH(3) group. In addition, the H atom produced in the H atom formation channel appears to be mostly from the CH(3) group with some contribution from the CCH group.

20.
J Chem Phys ; 121(13): 6302-8, 2004 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-15446925

RESUMO

The F+C2H3CH3 reaction has been investigated using the crossed molecular beam technique. Three reaction channels have been observed in this reaction: H+C3H5F, CH3+C2H3F, and HF+C3H5. Time-of-flight spectra as well as product laboratory angular distributions have been measured for the HF, C2H3F, and C3H5F products from these three channels. Relative branching ratios of the three observed reaction channels have also been estimated. Experimental results indicate that these different channels exhibit significantly different reaction dynamics.

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