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1.
Chem Commun (Camb) ; 55(65): 9653-9656, 2019 Aug 21.
Artigo em Inglês | MEDLINE | ID: mdl-31342021

RESUMO

The fast and accurate real-time monitoring of hydrogen peroxide (H2O2) secreted from living cells plays a critical role in clinical diagnosis and management. Herein, we report low-cost and self-supported MoS2 nanosheet arrays for non-enzymatic eletrochemical H2O2 detection. Under the optimal test conditions, such MoS2 electrodes exhibit extremely promising electrocatalytic performance with a low detection limit of 1.0 µM (S/N = 3) and an excellent sensitivity of 5.3 mA mM-1 cm-2. Furthermore, the detection of the trace amount of H2O2 secreted from live A549 cancer cells was successfully performed with this biosensor.


Assuntos
Dissulfetos/química , Peróxido de Hidrogênio/análise , Molibdênio/química , Nanoestruturas/química , Células A549 , Técnicas Biossensoriais/métodos , Carbono/química , Dissulfetos/síntese química , Técnicas Eletroquímicas/métodos , Humanos , Limite de Detecção
2.
Food Chem ; 299: 125116, 2019 Nov 30.
Artigo em Inglês | MEDLINE | ID: mdl-31295637

RESUMO

The effects of exogenous melatonin treatment on the enzymatic browning and nutritional quality of fresh-cut pear fruit were investigated. Fresh-cut fruit soaked with 0, 0.05, 0.1 and 0.5 mM melatonin were stored at 4 °C. Our results showed that 0.1 mM melatonin treatment was optimal for reducing the surface browning and maintaining the titratable acidity of the fresh-cut fruit, which significantly decreased MDA and H2O2 contents and the growth of microorganism, enhanced total phenolic content and antioxidant capacity, and delayed the reduction of ascorbic acid. Furthermore, melatonin treatment at 0.1 mM decreased the expression of genes involving in enzymatic browning pathway including POD, PPO1, PPO5 and LOX1, and reduced PPO activity. Moreover, this treatment increased the expression of PAL and CHS, and enhanced PAL and CHS activities. These results showed that melatonin treatment might be a promising strategy to alleviate browning and improve the nutritional quality of fresh-cut pear fruit.


Assuntos
Frutas/efeitos dos fármacos , Melatonina/farmacologia , Valor Nutritivo , Pyrus/efeitos dos fármacos , Antioxidantes/análise , Antioxidantes/metabolismo , Ácido Ascórbico/análise , Ácido Ascórbico/metabolismo , Armazenamento de Alimentos , Frutas/química , Frutas/metabolismo , Frutas/microbiologia , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Peróxido de Hidrogênio/análise , Peróxido de Hidrogênio/metabolismo , Malondialdeído/análise , Malondialdeído/metabolismo , Fenóis/análise , Pyrus/química , Pyrus/genética , Pyrus/metabolismo
3.
Food Chem ; 296: 56-62, 2019 Oct 30.
Artigo em Inglês | MEDLINE | ID: mdl-31202306

RESUMO

Autophagy, a mechanism of recycling intracellular constituents, favors plant growth, especially under nutrient starvation. However, autophagy's role in regulating postharvest fruit senescence is unclear. Here, effects of the autophagy inhibitor hydroxychloroquine (HCQ) and activator LiCl on postharvest jujube fruit senescence were investigated. HCQ significantly reduced weight loss and decay incidence, and enhanced firmness compared with those of the control. LiCl had the opposite effects. Protein oxidation and H2O2 increased significantly in LiCl-treated compared with HCQ-treated fruit. The contents of vitamin C, total thiol, and phenolics, and total antioxidant capacity and DPPH-radical scavenging capacity, followed the order: HCQ > control > LiCl. The HCQ-mediated reduction in fruit respiration was significantly enhanced by ATP and partly reversed by 2,4-dinitrophenol, a mitochondrial uncoupler. Thus, jujube fruit senescence may be regulated by autophagy and the antioxidant capacity. A mechanism of autophagy-mediated postharvest fruit senescence involving mitochondrial biogenesis and respiration was proposed.


Assuntos
Autofagia/efeitos dos fármacos , Hidroxicloroquina/farmacologia , Nutrientes/metabolismo , Ziziphus/metabolismo , Antioxidantes/química , Ácido Ascórbico/química , Frutas/efeitos dos fármacos , Frutas/metabolismo , Peróxido de Hidrogênio/análise , Hidroxicloroquina/química , Cloreto de Lítio/farmacologia , Nutrientes/química , Fenóis/química , Temperatura Ambiente , Ziziphus/efeitos dos fármacos
4.
Bioelectrochemistry ; 129: 235-241, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31226524

RESUMO

During tribocorrosion of biomedical alloys, potentials may shift cathodically across the metal-oxide-electrolyte interface resulting in the increased reduction of local oxygen and water molecules. The products of reduction are thought to include reactive oxygen species (ROS) as well as hydroxide ions. Using fluorescent probes, developed for labeling intracellular ROS-based hydroxyl radicals (OH·) and hydrogen peroxide (H2O2), ROS generation due to reduction reactions at cathodically biased CoCrMo alloy surfaces was measured directly. Using terephthalic acid (TA) and pentafluorosulfonylbenzene-fluorescein (PFF) as fluorescent dosimeters, it was found that OH· and H2O2 concentrations increased up to 16 h and 2 h, respectively. Decreases in fluorescence past these time points were attributed to the continuous onset of reduction reactions consuming both the ROS and/or dosimeter. It was also found that voltages below and including -600 mV (vs. Ag/AgCl) produced measurable quantities of H2O2 after two hours of polarization, with concentrations increasing with decreasing potentials up to -1000 mV. The detection and quantification of ROS in a clinical setting could help us better understand the role of ROS in the inflammatory response as well as their impact on corrosion behavior of biomedical alloys.


Assuntos
Cromo/química , Cobalto/química , Corantes Fluorescentes/química , Peróxido de Hidrogênio/análise , Radical Hidroxila/análise , Molibdênio/química , Espécies Reativas de Oxigênio/análise , Ligas/química , Eletrodos , Fluoresceína/química , Oxirredução , Ácidos Ftálicos/química , Espectrometria de Fluorescência/métodos
5.
Anal Bioanal Chem ; 411(17): 3801-3810, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31172237

RESUMO

The convenience of colorimetric sensors is useful for practical applications. In this work, we constructed a novel colorimetric sensor with magnetic separation ability that can be operated in nearly neutral conditions and achieve one-step detection of metabolites. Magnetic Cu doped Fe3O4@FeOOH magnetic nanocomposite (Cu/Fe3O4@FeOOH) with an oxygen vacancy was prepared by a one-step self-assembly hydrothermal method, and fully characterized by different methods. The oxygen vacancy generated by the incorporation of Cu2+ cations into the Fe3O4@FeOOH structure was confirmed to be a vital reactive site for enhancing the catalytic activity, which opens up a new way of designing highly efficient enzyme mimics. Benefiting from its inherent horseradish-peroxidase-like activity, a simple and selective enzyme-based colorimetric sensor was developed for one-step detection of H2O2 and cholesterol, and 3,3',5,5'-tetramethylbenzidine was catalyzed by H2O2 to generate a colored product of oxidized 3,3',5,5'-tetramethylbenzidine for signaling. H2O2 and cholesterol can be linearly detected in the same range from 0.01 to 0.4 mmol L-1 with detection limits of 0.0075 mmol L-1 and 0.0082 mmol L-1, respectively. The proposed colorimetric sensor has satisfactory reusability, accuracy, and practicability in human serum samples, indicating its potential application for the detection of different metabolites in the fields of life science and analytical science. Graphical abstract.


Assuntos
Técnicas Biossensoriais/métodos , Colorimetria/métodos , Cobre/química , Óxido Ferroso-Férrico/química , Peroxidase do Rábano Silvestre/química , Concentração de Íons de Hidrogênio , Magnetismo , Nanopartículas Metálicas/química , Benzidinas/química , Colesterol/sangue , Espectroscopia de Ressonância de Spin Eletrônica , Peróxido de Hidrogênio/análise , Microscopia Eletrônica de Transmissão , Oxirredução , Espectroscopia Fotoeletrônica , Reprodutibilidade dos Testes , Análise Espectral Raman , Difração de Raios X
6.
Anal Bioanal Chem ; 411(21): 5481-5488, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31236648

RESUMO

The mechanism behind the variation in the photoluminescence (PL) of a MoS2 nanohybrid material with pH was investigated. Highly fluorescent MoS2 quantum dots dispersed across MoS2 nanosheets (MoS2 QDNS) were synthesized by a hydrothermal route in the presence of NaOH. Upon reducing the pH from 13 to 6.5, the PL intensity was markedly quenched. The removal of dangling sulfur atoms by adding mineral acids could be a plausible mechanism for this PL quenching, together with the inner filter effect and Förster resonance energy transfer due to the resulting species. A label-free turn-on fluorescence sensor for H2O2 was developed using this hybrid material. The PL of the acidified MoS2 QDNS at pH 6.5 increased (i.e., recovered) linearly with the concentration of H2O2. The dynamic range of the sensor was found to be 2-94 µM with a limit of detection (LOD) of 2 µM. This sensing strategy was also extended for the detection of glucose by appending glucose oxidase (GOx) as a catalyst. In the presence of GOx, glucose oxidizes to gluconic acid and H2O2, so the original level of glucose can be estimated by determining the H2O2 present. The absence of a complicated enzyme immobilization step is the prime advantage of the present glucose sensor. The current work exemplifies the utility of MoS2-based nanoparticle systems in the biological sensor domain. Graphical abstract.


Assuntos
Dissulfetos/química , Peróxido de Hidrogênio/análise , Concentração de Íons de Hidrogênio , Molibdênio/química , Transferência Ressonante de Energia de Fluorescência , Glucose Oxidase/análise , Limite de Detecção , Medições Luminescentes
7.
Anal Chim Acta ; 1075: 91-97, 2019 Oct 10.
Artigo em Inglês | MEDLINE | ID: mdl-31196427

RESUMO

Antioxidants are important to protect and maintain biological barriers, such as the skin. Antioxidant effects are often assessed using clinical trials, however these tests are costly and time consuming. In this work we introduce a skin membrane-covered oxygen electrode (SCOE) as an in vitro tool for monitoring H2O2 and antioxidant reactions in skin. The SCOE gives amperometric response to H2O2 concentrations down to 0.05 mM. More importantly, the electrode allows measurements of polyphenol penetration and reaction with H2O2 in skin. Measurements with SCOE show that lipophilic polyphenols such as quercetin, piceatannol, resveratrol, and plant extract from Plantago major impose their antioxidant effect in skin within 2-20 min. Rutin is however too hydrophilic to penetrate into stratum corneum and therefore cannot deliver its antioxidant effect during similar time interval. The measurements are interpreted considering polyphenol partition-penetration through stratum corneum and the reaction with the H2O2-catalase system in the skin. The contribution of other enzymes will be addressed in the future.


Assuntos
Antioxidantes/metabolismo , Peróxido de Hidrogênio/análise , Inflamação/metabolismo , Polifenóis/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Pele/metabolismo , Animais , Técnicas Biossensoriais/instrumentação , Técnicas Biossensoriais/métodos , Catalase/metabolismo , Técnicas Eletroquímicas/instrumentação , Técnicas Eletroquímicas/métodos , Eletrodos , Peróxido de Hidrogênio/metabolismo , Hidroquinonas/metabolismo , Limite de Detecção , Oxigênio/química , Extratos Vegetais/química , Plantago/química , Pele/enzimologia , Suínos
8.
Int J Nanomedicine ; 14: 2451-2464, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31040668

RESUMO

Background: Acute myocardial infarction (AMI), usually caused by atherosclerosis of coronary artery, is the most severe manifestation of coronary artery disease which results in a large amount of death annually. A new diagnosis approach with high accuracy, reliability and low measuring-time-consuming is essential for AMI quick diagnosis. Purpose: The objective of this study was to develop a new point-of-care testing system with high accuracy and reliability for AMI quick diagnosis. Patients and methods: 50 plasma samples of acute myocardial infarction patients were analyzed by developed Smartphone-Assisted Pressure-Measuring-Based Diagnosis System (SPDS). The concentration of substrate was firstly optimized. The effect of antibody labeling and matrix solution on measuring result were then evaluated. And standard curves for cTnI, CK-MB and Myo were built for clinical sample analysis. The measuring results of 50 clinical samples were finally evaluated by comparing with the measuring result obtained by CLIA. Results: The concentration of substrate H2O2 was firstly optimized as 30% to increase measuring signal. A commercial serum matrix was chosen as the matrix solution to dilute biomarkers for standard curve building to minimize matrix effect on the accuracy of clinical plasma sample measuring. The standard curves for cTnI, CK-MB and Myo were built, with measuring dynamic range of 0-25 ng/mL, 0-33 ng/mL and 0-250 ng/mL, and limit of detection of 0.014 ng/mL, 0.16 ng/mL and 0.85 ng/mL respectively. The measuring results obtained by the developed system of 50 clinical plasma samples for three biomarkers matched well with the results obtained by chemiluminescent immunoassay. Conclusion: Due to its small device size, high sensitivity and accuracy, SPDS showed a bright potential for point-of-care testing (POCT) applications.


Assuntos
Pressão Sanguínea , Infarto do Miocárdio/diagnóstico , Infarto do Miocárdio/fisiopatologia , Smartphone , Anticorpos/metabolismo , Biomarcadores/sangue , Catálise , Feminino , Humanos , Peróxido de Hidrogênio/análise , Masculino , Pessoa de Meia-Idade , Infarto do Miocárdio/sangue , Nanopartículas/química , Platina/química , Padrões de Referência , Reprodutibilidade dos Testes , Sensibilidade e Especificidade , Eletricidade Estática
9.
Talanta ; 200: 450-457, 2019 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-31036208

RESUMO

Non enzymatic detection of NADH and H2O2 is of practical significance for both environmental and biological prospective. However, there is no simple, straight forward electrochemical sensor available for sensing of them in real samples. Addressing this challenge, we report a simple stimuli responsive aminophenol, pre-anodized screen printed carbon electrode (SPCE*/AP) based electrochemical probes for dual detection of NADH and H2O2. Aminophenol prepared and adsorbed on the electrode from aminophenylboronic acid via boronic acid deprotection with H2O2. The SPCE*/AP fabricated with this process was characterized by cyclic voltammetry (CV), scanning electron microscope (SEM), Raman spectroscopy, UV-visible spectroscopy, and X-ray photoelectron spectroscopy (XPS). Amperometric detection results showed that SPCE*/AP electrodes exhibited linearity from 50 µM to 500 µM and from 200 µM to 2 mM with a detection limit (S/N = 3) of 4.2 µM and 28.9 µM for NADH and H2O2, respectively. Excellent reproducibility and selectivity for NADH and H2O2 were observed for this electrochemical platform. In addition, the matrix effect was investigated further using the same technique to analyze NADH and H2O2 in human urine samples, human serum samples, cell culture medium (containing 10% fetal bovine serum, FBS), and environmental water samples (tap water and rain water). Also, the present sensor demonstrated promising outcomes with living cells (normal cells and cancer cells).


Assuntos
Aminofenóis/química , Técnicas Eletroquímicas , Corantes Fluorescentes/química , Peróxido de Hidrogênio/análise , NAD/análise , Células 3T3 , Animais , Carbono/química , Linhagem Celular Tumoral , Eletrodos , Humanos , Camundongos
10.
Talanta ; 200: 511-517, 2019 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-31036217

RESUMO

Microfluidic paper-based analytical devices (µPADs) for detection of hydrogen peroxide and glucose have been developed. The analytical performance of colorimetric detection using the conventional starch-iodine color reaction has been significantly improved by using gelatin as the surface modifier which retains the enzyme activity in the dry filter paper strip, improves antioxidability, as well as decreases the strong background signal. Under optimal conditions, the color intensities show a good linear relationship with glucose concentration ranging from 0.5 to 5 mM and hydrogen peroxide concentration from 0.5 to 6 mM, with the detection limit of 0.05 mM and 0.1 mM, respectively. In addition, the accuracy of colorimetric sensor has been successfully assessed in detecting glucose from real human serum samples and recovery value ranges from 95.7% to 97%, which are approaching to the glucose oxidase endpoint. The new colorimetric assay exhibits high sensitivity, good selectivity, acceptable stability and reproducibility. The present approach is promising for monitoring glucose for point of care diagnostic applications, especially in regions with resource-limited settings.


Assuntos
Colorimetria , Gelatina/química , Glucose/análise , Peróxido de Hidrogênio/análise , Iodetos/química , Técnicas Analíticas Microfluídicas , Papel , Amido/química , Humanos
11.
Analyst ; 144(11): 3643-3648, 2019 Jun 07.
Artigo em Inglês | MEDLINE | ID: mdl-31073567

RESUMO

Using fluorescent probes to detect endogenous hydrogen peroxide, which is associated with many diseases in the human body, remains an essential technique. Cyanine fluorochromes are a class of dyes that have attracted much attention and are widely used in the synthesis of fluorescent probes. In this article, a novel near-infrared (NIR) fluorescence probe for the detection of hydrogen peroxide was constructed and successfully applied to imaging endogenous hydrogen peroxide in vivo. Notably, probe 1 was designed by connecting 4-(bromomethyl)benzeneboronic acid pinacol ester as the sensing unit to the IR-780 hemicyanine skeleton, which exhibits excellent properties like NIR fluorescence emission over 700 nm. Probe 1 has satisfactory sensitivity to hydrogen peroxide with a low detection limit of 0.14 µM (S/N = 3), attributed to a responding mechanism that leads to the oxidation of phenylboronic acid pinacol ester and thereby releases fluorophore 2. Moreover, probe 1 displays excellent selectivity towards hydrogen peroxide over other substances. Taking advantage of these properties, the probe proved to be cell-permeable. Based on the results of N-acetylcysteine and rotenone together, probe 1 is capable of clearly visualizing endogenously produced hydrogen peroxide in living HepG2 cells and mice. The superior performance of the probe, as a reliable chemical tool, makes it of great potential application for exploring the role played by hydrogen peroxide in biological systems.


Assuntos
Ácidos Borônicos/química , Corantes Fluorescentes/química , Peróxido de Hidrogênio/análise , Indóis/química , Acetilcisteína/farmacologia , Animais , Antioxidantes/farmacologia , Ácidos Borônicos/síntese química , Ácidos Borônicos/toxicidade , Fluorescência , Corantes Fluorescentes/síntese química , Corantes Fluorescentes/toxicidade , Células Hep G2 , Humanos , Peróxido de Hidrogênio/química , Peróxido de Hidrogênio/metabolismo , Concentração de Íons de Hidrogênio , Indóis/síntese química , Indóis/toxicidade , Limite de Detecção , Camundongos Endogâmicos BALB C , Microscopia Confocal/métodos , Microscopia de Fluorescência/métodos , Oxirredução , Rotenona/farmacologia , Temperatura Ambiente
12.
BMC Vet Res ; 15(1): 144, 2019 May 14.
Artigo em Inglês | MEDLINE | ID: mdl-31088564

RESUMO

BACKGROUND: Biomarkers of oxidative stress in pigs have been measured in serum/plasma samples. However, blood collection in pigs can be highly stressful to the animals. Saliva is a biological fluid with several advantages in pigs over blood, since it can be easily collected without stress to the animals, being therefore an ideal sample in this species. The objective of this study was the validation of assays for the evaluation of oxidative stress status in saliva of pigs. For this purpose, three assays commonly used to evaluate the total antioxidant capacity (TAC): trolox equivalent antioxidant capacity (TEAC), cupric reducing antioxidant capacity (CUPRAC), and ferric reducing ability of plasma (FRAP)), one individual antioxidant (uric acid) and two assays to evaluate oxidant concentrations (advanced oxidation protein products (AOPP) and hydrogen peroxide (H2O2)) were measured and validated in porcine saliva. In addition, the possible changes of these assays in sows' saliva during lactation were be studied. RESULTS: The methods had intra- and inter-assays coefficient of variation lower than 15%. They also showed an adequate linearity and recovery, and their detection limits were low enough to detect the analytes in saliva of pigs. Overall the analytical validation tests showed that the assays used in our study are valid and reliable for the evaluation of oxidative stress in porcine saliva. In addition, it was observed that these salivary biomarkers can change in a situation of oxidative stress such as lactation in sows. CONCLUSIONS: All assays for salivary biomarkers of oxidative stress evaluated in this study have demonstrated a high analytical accuracy and low imprecision. In addition, it has been observed that these biomarkers showed significant changes in a situation of oxidative stress such as lactation in sows. Therefore, this study opens a new possibility of using saliva as a non-invasive sample to evaluate oxidative stress in pigs.


Assuntos
Biomarcadores/análise , Lactação/fisiologia , Estresse Oxidativo , Saliva/química , Sus scrofa/fisiologia , Produtos da Oxidação Avançada de Proteínas/análise , Animais , Antioxidantes/análise , Feminino , Peróxido de Hidrogênio/análise , Ácido Úrico/análise
13.
Ultrason Sonochem ; 56: 254-263, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31101261

RESUMO

A novel and cost-effective synthesis of biopolymer-based organic and inorganic composite materials have received substantial attention in a broad range application including electroanalysis of small molecules. In this perspective, we report the synthesis of gum guar (guar) biopolymer stabilized cupric oxide decorated on exfoliated graphite (GR-guar/CuO) composite. Different physicochemical characterization methods were used to confirm the successful exfoliation of graphite and formation of the GR-guar/CuO composite. A simple sonochemical method has been used for the preparation of guar stabilized exfoliated graphite (GR-guar). The flower-like CuO on GR-guar and guar stabilized CuO (CuO-guar) composites were synthesized using a hydrothermal method. Cyclic voltammetric studies revealed that the GR-guar/CuO composite modified screen-printed carbon electrode (SPCE) had enhanced electro-reduction ability towards H2O2 than GR-guar and pristine graphite/CuO-guar modified SPCEs. Under optimized experimental conditions, the GR-guar/CuO composite modified electrode detects H2O2 in the response ranges from 0.02 to 1296.6 µM. The sensor shows a lower detection limit of 5.8 nM with high sensitivity. The as-prepared GR-guar/CuO composite sensor is highly reproducible and had excellent selectivity and practicality towards the detection of H2O2. Consequently, the fabricated sensor can be used for the accurate detection of H2O2 in real samples.


Assuntos
Soluções para Lentes de Contato/química , Cobre/química , Galactanos/síntese química , Grafite/química , Peróxido de Hidrogênio/análise , Mananas/síntese química , Leite/química , Gomas Vegetais/síntese química , Ondas Ultrassônicas , Animais , Catálise , Técnicas de Química Sintética , Eletroquímica , Modelos Moleculares , Conformação Molecular
14.
Food Chem ; 292: 114-120, 2019 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-31054654

RESUMO

The determination of ethanol is one of the most important parameters in the fermentation industry, influencing not only the production yield and the quality of the product, but also its commercial value. In addition to the traditional approach based on distillation/density, procedure that is considered laborious and time-consuming, methods based on chromatography are widely used. Alternatives using electrochemical, spectroscopic and colorimetric techniques have been also proposed for alcohol analysis. In general, these methods not only offer limited throughput, but also require harsh reaction conditions and/or complex instrumentation. Aiming to address these shortcomings, we propose a fast, simple and clean analytical approach for the determination of primary alcohols based on the photochemical oxidation under UV-LED irradiation in the presence of H2O2. The proposed method was successfully applied to the analysis of 12 different types of alcoholic beverages with an alcohol content ranging from 5% v/v (beer) to 53% v/v (whiskey).


Assuntos
Eletroforese Capilar/métodos , Etanol/análise , Bebidas Alcoólicas/análise , Ácido Benzoico/análise , Etanol/química , Histidina/análise , Peróxido de Hidrogênio/análise , Oxirredução , Raios Ultravioleta
15.
Talanta ; 199: 628-633, 2019 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-30952307

RESUMO

Parkinson's disease (PD) severely affects life quality of patients and has brought huge economic burden to health system worldwide. Previous studies have shown that the abnormal expression of hydrogen peroxide (H2O2) in the brain is closely related to the development of neurodegenerative diseases such as PD. Herein, we designed a novel deep-red H2O2 fluorogenic probe PB1 to detect the level of H2O2in vivo. PB1 showed a highly selectivity response to H2O2 over other reactants such as reactive oxygen/nitrogen species, biothiols and various ions in aqueous solution at physiological pH. We have demonstrated that PB1 possesses an excellent response to H2O2 in the cells and in the brain tissue of drosophila from confocal fluorescence imaging. These results suggested that PB1 holds great potential in the study of the relationship between H2O2 overexpression and PD.


Assuntos
Corantes Fluorescentes/química , Peróxido de Hidrogênio/análise , Imagem Óptica , Doença de Parkinson/diagnóstico , Doença de Parkinson/metabolismo , Pirimidinas/química , Corantes Fluorescentes/síntese química , Células Hep G2 , Humanos , Concentração de Íons de Hidrogênio , Microscopia Confocal , Microscopia de Fluorescência , Estrutura Molecular , Pirimidinas/síntese química
16.
Analyst ; 144(10): 3347-3356, 2019 May 21.
Artigo em Inglês | MEDLINE | ID: mdl-30976770

RESUMO

A new fluconazole-functionalized polyoxometalate-based metal-organic framework (POMOF) [Ag3(FKZ)2(H2O)2][H3SiW12O40] (AgFKZSiW12) was successfully constructed, and its polypyrrole (PPy) coated composite AgFKZSiW12@PPy was also obtained via a facile 'in situ' oxidation polymerization process. The peroxidase-like activity evaluation indicates that the maximized synergistic effect from the integration of PPy, SiW12 clusters, HFKZ drug molecules, and Ag ions deeply enhanced the overall performance. More importantly, AgFKZSiW12@PPy exhibits the fastest response time (30 s) among all the reported peroxidase mimics to date, including the pristine AgFKZSiW12 (2 min). Moreover, the AgFKZSiW12@PPy-based colorimetric biosensing platform towards H2O2 and ascorbic acid (AA) exhibits limits of detection (LOD) as low as 0.12 µM and 2.7 µM, respectively. This work reveals a promising prospect in medical diagnosis and biotechnology for colorimetric biosensor fabrication with high performance through the introduction of PPy.


Assuntos
Ácido Ascórbico/sangue , Fluconazol/química , Peróxido de Hidrogênio/análise , Estruturas Metalorgânicas/química , Polímeros/química , Pirróis/química , Materiais Biomiméticos/química , Técnicas Biossensoriais/métodos , Catálise , Colorimetria/métodos , Humanos , Cinética , Limite de Detecção , Modelos Químicos , Peroxidase/química
17.
Anal Chim Acta ; 1065: 12-20, 2019 Aug 13.
Artigo em Inglês | MEDLINE | ID: mdl-31005144

RESUMO

We are reporting an innovative building-block for the development of biosensors based on the non-covalent functionalization of multi-walled carbon nanotubes (MWCNTs) with avidin (MWCNTs-avidin). In this work, at variance with previous reports, avidin has the double role of simultaneously being the exfoliating agent of MWCNTs and the platform for anchoring different biotinylated biomolecules. The optimum dispersion was obtained by sonicating for 5.0 min 0.50 mgmL-1 MWCNTs with 1.00 mgmL-1 avidin solution prepared in 50:50 v/v ethanol/water. As proof-of-concept, we immobilized biotinylated horseradish peroxidase (b-HRP) at glassy carbon electrodes (GCE) modified with MWCNTs-avidin to develop a hydrogen peroxide biosensor using hydroquinone as redox mediator. Surface plasmon resonance, electrochemical impedance spectroscopy, cyclic voltammetry and amperometry demonstrated that, even after the partial denaturation of avidin due to the drastic conditions used to functionalize the MWCNTs, it preserves the biorecognition properties and efficiently interacts with biotinylated horseradish peroxidase (b-HRP). The analytical characteristics of the resulting hydrogen peroxide biosensor are the following: linear range between 1.0 × 10-6 M and 1.4 × 10-5 M, sensitivity of (1.37 ±â€¯0.04) x 105 µAM-1, detection limit of 24 nM and reproducibility of 2.9%. The sensor was challenged with different samples, a mouthwash solution, human blood serum and milk, with very good performance.


Assuntos
Avidina/química , Técnicas Biossensoriais , Técnicas Eletroquímicas , Peroxidase do Rábano Silvestre/metabolismo , Peróxido de Hidrogênio/análise , Nanotubos de Carbono/química , Animais , Espectroscopia Dielétrica , Eletrodos , Peroxidase do Rábano Silvestre/química , Humanos , Leite/química , Ressonância de Plasmônio de Superfície
18.
Cell Biochem Funct ; 37(4): 245-255, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-31017709

RESUMO

Damage to podocytes is a key event in glomerulopathies. While energy dense food can contribute to kidney damage, the role of the orixegenic hormone "ghrelin" in podocyte biology is still unknown. In the present study, we investigated the effect of ghrelin on podocyte survival as well as the signalling pathways mediating ghrelin effect in immortalized cultured rat podocytes. RT-PCR analysis revealed that GHS-R1 is expressed in rat podocytes. Western blot analysis showed that ghrelin upregulated COX-2 protein expression in a time and dose-dependent manner. Additionally, ghrelin activated P38 MAPK, AKT, and ERK1/2 pathways and also induced P38 MAPK phosphorylation in high glucose conditions. Ghrelin induced ROS release and dose dependently reduced podocyte survival. Ghrelin mediated podocyte cell death was partially reversed by pharmacologically inhibiting P38 MAPK or phospholipase C (PLC). Furthermore, PLC inhibitor (U73122) inhibited ghrelin induced P38 MAPK activation. While PI3K inhibitor (LY294002) was without effect on cell survival or P38 MAPK activation, it inhibited ghrelin induced ERK1/2 phosphorylation. Finally, ghrelin induced TAU phosphorylation was reversed by pharmacologic inhibitors of either P38 MAPK or PKA. In conclusion, ghrelin activated harmful molecular pathways in podocytes that can be damaging to the glomerular filtration barrier SIGNIFICANCE OF THE STUDY: Endocrine derangements secondary to obesity are major players in the aetiology of renal injuries. Furthermore, energy dense diet is thought to be the major element in developing obesity. Appetite and increase in energy intake are regulated by complex hormonal pathways which mainly include the orexigenic hormone "ghrelin" in addition to leptin. To date no study have highlighted a significant role for ghrelin in kidney biology, and therefore, it is thought that its endocrine effect is mostly limited to adipose tissue metabolism and appetite regulation. In this study, we first showed that ghrelin receptor is expressed on glomerular podocytes. Also, ghrelin showed negative impact on podocyte survival through modulating signalling pathways such as P38 MAPK and AKT known to play a key role in podocyte health. Moreover, the negative effects of ghrelin on podocytes were further exacerbated in hyperglycemic conditions. Of note, podocytes contribute to the formation and the maintenance of the glomerular filtration barrier and thus are important for normal renal function. Therefore, ghrelin secretion in the context of obesity could be involved in the aetiology of kidney injury, a well-known hallmark found in obese patients.


Assuntos
Grelina/farmacologia , Podócitos/citologia , Podócitos/efeitos dos fármacos , Transdução de Sinais/efeitos dos fármacos , Animais , Cálcio/análise , Cálcio/metabolismo , Sobrevivência Celular/efeitos dos fármacos , Células Cultivadas , Peróxido de Hidrogênio/análise , Peróxido de Hidrogênio/metabolismo , Camundongos , Podócitos/metabolismo
19.
Food Chem ; 286: 329-337, 2019 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-30827615

RESUMO

The effects of exogenous progesterone (PROG) on chilling injury (CI) in postharvest banana fruit were investigated. Concentration screening tests showed that 10-5 mol/l PROG was most effective in reducing CI in banana fruit stored for 25 d at 5 ±â€¯1 °C, but did not markly increase PROG content of pulps. This PROG treatment significantly reduced the electrolyte leakage, levels of malondialdehyde, O2- production rate and H2O2 contents in banana compared with control fruit. The PROG treatment caused an early induction of alternative oxidase (AOX) at the transcript and protein level to reduce the generation of O2- and H2O2. PROG treatment also enhanced the transcript levels and activities of antioxidant enzymes and maintained higher levels of reduced glutathione and ascorbic acid than the control fruit. These results suggested that PROG attenuating CI in banana fruit may be attributed to the induction of AOX and the improvement of enzyme and non-enzymatic antioxidant defenses.


Assuntos
Antioxidantes/metabolismo , Proteínas Mitocondriais/metabolismo , Musa/efeitos dos fármacos , Oxirredutases/metabolismo , Proteínas de Plantas/metabolismo , Progesterona/farmacologia , Antioxidantes/química , Temperatura Baixa , Eletrólitos/metabolismo , Frutas/efeitos dos fármacos , Frutas/metabolismo , Glutationa/metabolismo , Peróxido de Hidrogênio/análise , Malondialdeído/metabolismo , Proteínas Mitocondriais/genética , Musa/metabolismo , Oxirredutases/genética , Proteínas de Plantas/genética , Espécies Reativas de Oxigênio/metabolismo
20.
J Immunol Res ; 2019: 1529189, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30882002

RESUMO

Paracoccidioidomycosis (PCM), a systemic mycosis endemic in Latin America, occurs after inhalation of mycelial components of Paracoccidioides spp. When the fungus reaches the lungs and interacts with the alveolar macrophages and other cells, phagocytic cells such as neutrophils and monocytes are immediately recruited to the injured site. The interaction between surface molecules of pathogens and homologous receptors, present on the surface membrane of phagocytes, modulates the innate immune cell activation. Studies have shown the importance of fungal recognition by the Dectin-1 receptor, which can induce a series of cellular protective responses against fungi. The objective of the present study was to evaluate Dectin-1 receptor expression and the effector mechanisms of human monocytes and neutrophils activated or not with different cytokines, such as IFN-γ, TNF-α, and GM-CSF, followed by the challenge with Paracoccidioides brasiliensis (P. brasiliensis or Pb265). Therefore, analysis of Dectin-1 receptor expression was done by flow cytometry whereas the effector mechanisms were evaluated by fungal recovery by colony-forming unit (CFU) counting and hydrogen peroxide (H2O2) production. Our results showed that, after treatment with IFN-γ, TNF-α, and GM-CSF and challenge with Pb265, cells, especially monocytes, demonstrated an increase in Dectin-1 expression. Both types of cells treated with the cytokines exhibited a decreased fungal recovery and, conversely, an increased production of H2O2. However, when cultures were treated with an anti-Dectin-1 monoclonal antibody, to block the P. brasiliensis binding, a decrease in H2O2 production and an increase in fungal recovery were detected. This effect was observed in all cultures treated with the specific monoclonal antibody. These results show the involvement of the Dectin-1 receptor in fungal recognition and its consequent participation in the induction of the killing mechanisms against P. brasiliensis.


Assuntos
Citocinas/farmacologia , Lectinas Tipo C/metabolismo , Paracoccidioidomicose/imunologia , Fagócitos/imunologia , Contagem de Colônia Microbiana , Feminino , Fator Estimulador de Colônias de Granulócitos e Macrófagos/farmacologia , Humanos , Peróxido de Hidrogênio/análise , Interferon gama/farmacologia , Lectinas Tipo C/genética , Masculino , Monócitos/efeitos dos fármacos , Monócitos/imunologia , Neutrófilos/efeitos dos fármacos , Neutrófilos/imunologia , Paracoccidioides , Fagócitos/efeitos dos fármacos
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