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1.
Clin Exp Rheumatol ; 41(8): 1612-1617, 2023 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-37382464

RESUMEN

OBJECTIVES: Fibrosis is the dominant hallmark of systemic sclerosis (SSc). Several mechanisms have been proposed to drive the disease process, but how these relate to skin fibrosis is poorly understood. METHODS: We performed a cross-sectional study on archival skin biopsies from 18 SSc patients and four controls. Dermal fibrosis and inflammatory cell infiltration were scored in HE and Masson's Trichrome-stained sections. The presence of senescence was defined by P21 and/or P16 positivity in Ki-67 negative cells. Endothelial to mesenchymal transition (EndMT) was identified by co-localisation of CD31 and α-SMA in immunofluorescent double-stained sections, and by an enclosure of ERG positive endothelial cell nuclei by α-SMA stained cytoplasm in immunohistochemical double staining. RESULTS: The histological dermal fibrosis score of SSc skin biopsies was correlated with the modified Rodnan skin score (rho 0.55, p=0.042). Staining for markers of cellular senescence on fibroblasts was correlated with fibrosis score, inflammatory score, and CCN2 staining on fibroblasts. Moreover, EndMT was more abundant in skin from patients with SSc (p<0.01) but did not differ between groups with different fibrosis severity. The frequency of these EndMT features increased with the abundance of senescence markers and CCN2 on fibroblasts and dermal inflammation. CONCLUSIONS: EndMT and fibroblast senescence were more abundant in skin biopsies from SSc patients. This finding indicates that both senescence and EndMT are involved in the pathway leading to skin fibrosis and might be valuable biomarkers and/or possible targets for novel therapeutic interventions.


Asunto(s)
Esclerodermia Sistémica , Humanos , Estudios Transversales , Esclerodermia Sistémica/patología , Fibrosis , Piel/patología , Fibroblastos/metabolismo , Biopsia , Senescencia Celular
2.
J Formos Med Assoc ; 119(1 Pt 3): 480-487, 2020 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-31303456

RESUMEN

BACKGROUND: Patients who have symptoms of sicca, such as dry eyes and mouth, may have Sjögren's syndrome (SS). However, the conservative culture makes patients hesitate to undergo an invasive biopsy, which contributes to the difficulty of confirming a diagnosis. We aimed to identify the characteristics of patients with sicca symptoms to develop a better predictive value for each item included in the three different diagnostic criteria for SS and clarify the best diagnostic tools for the local population. METHODS: This is a single-center retrospective case-control study from January 2016 to December 2017. Patients who underwent sialoscintigraphy because of clinical symptoms of xerostomia and xerophthalmia at one medical center were reviewed via the patients' electronic medical records. RESULTS: Of 515 patients enrolled, the severity of results for sialoscintigraphy and Schirmer's test was correlated with a diagnosis of SS and generated receiver operator characteristic curve. The area under curve (AUC) was 0.603 for positive Schirmer's test, 0.687 for positive anti-Ro/La results, 0.893 for a positive salivary gland biopsy. The AUC was 0.626 and 0.602 for Schirmer's test which is redefined as <10 mm/5 minutes in either eye and according to 2016 the American College of Rheumatology/ European League Against Rheumatism criteria, respectively. CONCLUSION: Our results indicate the cut-off point for defining a positive test result in the Schirmer's test is worth modified to <10 mm/5 minutes in either eye.


Asunto(s)
Síndrome de Sjögren/diagnóstico , Xeroftalmia/diagnóstico , Xerostomía/diagnóstico , Adulto , Anciano , Técnicas y Procedimientos Diagnósticos , Femenino , Humanos , Masculino , Persona de Mediana Edad , Curva ROC , Estudios Retrospectivos , Glándulas Salivales/patología , Síndrome de Sjögren/complicaciones , Taiwán , Xeroftalmia/etiología , Xerostomía/etiología
3.
Nutrients ; 16(10)2024 May 09.
Artículo en Inglés | MEDLINE | ID: mdl-38794673

RESUMEN

Pulses-comprising the dry, edible seeds of leguminous plants-have long been lauded for their culinary flexibility and substantial nutritional advantages. This scoping review aimed to map the evidence on how pulses contribute to overall human health. Four electronic databases were searched for clinical and observational studies in English. We identified 30 articles (3 cross-sectional studies, 1 federated meta-analysis, 8 prospective cohort studies, 1 before-and-after study, and 17 randomized controlled trials) that met our inclusion criteria. Predominant among the pulses studied were lentils, chickpeas, common bean varieties (e.g., pinto, black, navy, red, kidney), black-eyed peas, cowpeas, and split peas. Consumption modalities varied; most studies examined mixed pulses, while five isolated individual types. In intervention studies, pulses were incorporated into diets by allotting a fixed pulse serving on top of a regular diet or by substituting red meat with pulses, offering a comparative analysis of dietary effects. The health outcomes evaluated were multifaceted, ranging from lipid profiles to blood pressure, cardiovascular disease risk and mortality, type 2 diabetes and glycemic control, metabolic syndrome indicators, inflammatory markers, oxidative stress biomarkers, and hormonal profiles. The most frequently assessed study outcomes included changes in low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, systolic blood pressure, diastolic blood pressure, fasting blood sugar, hemoglobin A1c, waist circumference, and C-reactive protein or high-sensitivity C-reactive protein. This review should serve as a call to action for the scientific community to build upon the existing evidence, enriching our understanding of the nutritional and health-promoting attributes of pulses.


Asunto(s)
Dieta , Humanos , Fabaceae , Enfermedades Cardiovasculares/prevención & control , Semillas , Presión Sanguínea
4.
Nutrients ; 16(11)2024 May 21.
Artículo en Inglés | MEDLINE | ID: mdl-38892483

RESUMEN

Understanding the relationship between the intake of sugars and diet quality can inform public health recommendations. This systematic review synthesized recent literature on associations between sugar intake and diet quality in generally healthy populations aged 2 years or older. We searched databases from 2010 to 2022 for studies of any design examining associations between quantified sugar intake in the daily diet and dietary indexes (DIs) or micronutrient intakes. Different sugar types and diet quality measures were analyzed separately. We converted DI results to Pearson's r correlations and grouped indexes with or without a free or added sugar component to facilitate cross-study comparisons. Meta-analysis was deemed inappropriate. From 13,869 screened records, we included 27 cross-sectional studies. NUQUEST risk of bias ratings were neutral (n = 18 studies) or poor (n = 9), and strength of evidence by the GRADE approach was very low due to study design. Most studies reported negative associations for added and free sugars with diet quality indexes (r ranging from -0.13 to -0.42) and nutrients of public health concern (fiber, vitamin D, calcium, potassium), while associations with total sugars were mixed. Due to cross-sectional study designs, the clinical relevance of these findings is unclear. Prospective studies are needed to minimize confounding and inform causal relationships.


Asunto(s)
Azúcares de la Dieta , Humanos , Azúcares de la Dieta/administración & dosificación , Dieta , Estudios Transversales , Femenino , Adulto , Masculino , Dieta Saludable/estadística & datos numéricos , Niño , Persona de Mediana Edad , Adolescente , Micronutrientes/administración & dosificación , Preescolar , Adulto Joven , Anciano
5.
J Scleroderma Relat Disord ; 8(3): 241-246, 2023 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-37744043

RESUMEN

Introduction: Autologous haematopoietic stem cell transplantation improves event-free survival and lung function and reduces skin thickening in patients with progressive diffuse cutaneous systemic sclerosis. Anti-thymocyte globulin is a key lymphoablative constituent of conditioning protocols and is administered in a weight-based dosage. However, whether anti-thymocyte globulin exposure contributes to response to autologous haematopoietic stem cell transplantation and lymphocyte reconstitution in diffuse cutaneous systemic sclerosis patients is unknown. We aimed to explore the relationship between anti-thymocyte globulin exposure, lymphocyte reconstitution and treatment response in diffuse cutaneous systemic sclerosis patients undergoing autologous haematopoietic stem cell transplantation. Methods: A retrospective cohort of 15 diffuse cutaneous systemic sclerosis patients undergoing autologous haematopoietic stem cell transplantation was performed. Clinical characteristics and routine laboratory results were retrieved from electronic medical records. Anti-thymocyte globulin concentrations were measured in cryopreserved plasma samples at four time points (day 1 and week 1, 2 and 4) after stem cell reinfusion. Anti-thymocyte globulin exposure was estimated using a validated population pharmacokinetic model. Results: During a median follow-up of 45 months (interquartile range 19-66), 11 (73%) patients had a treatment response, and 4 (27%) were non-responders. Although all patients received the same weight-based anti-thymocyte globulin dosage, 7.5 mg/kg divided over 3 days, anti-thymocyte globulin exposure varied. Anti-thymocyte globulin exposure was higher in responders than in non-responders (163 AU*day/mL (interquartile range 153-183) and 137 AU*day/mL (interquartile range 101-149), respectively, p = .026). Anti-thymocyte globulin exposure was not correlated with lymphocyte reconstitution or infection rate. Conclusion: Weight-based dosing of anti-thymocyte globulin results in variable anti-thymocyte globulin exposure and treatment response across individuals.

6.
Front Med (Lausanne) ; 10: 1106560, 2023.
Artículo en Inglés | MEDLINE | ID: mdl-36923009

RESUMEN

Background: Connective tissue diseases-associated interstitial lung disease (CTD-ILD) is a heterogeneous condition that impairs quality of life and is associated with premature death. Progressive pulmonary fibrosis (PPF) has been identified as an important risk factor for poor prognosis. However, different criteria for PPF are used in clinical studies, which may complicate comparison between trials and translation of study findings into clinical practice. Methods: This is a retrospective single center study in patients with CTD-ILD. The prognostic relevance of PPF definitions, including INBUILD, ATS/ERS/JRS/ALAT 2022, and simplified progressive fibrosing (simplified PF) criteria, were examined in this cohort and validated in the other reported Dutch CTD-ILD cohort. Results: A total of 230 patients with CTD-ILD were included and the median follow-up period was six (3-9) years. Mortality risk was independently associated with age (adjusted HR 1.07, p < 0.001), smoking history (adjusted HR 1.90, p = 0.045), extent of fibrosis on high-resolution computed tomography (HRCT) at baseline (adjusted HR 1.05, p = 0.018) and baseline DLCO (adjusted HR 0.97, p = 0.013). Patients with regular pulmonary function tests in the first 2 years (adjusted HR 0.42, p = 0.002) had a better survival. The prognostic relevance for survival was similar between the three PPF criteria in the two cohorts. Conclusion: Higher age, smoking, increased extent of fibrosis and low baseline DLCO were associated with poor prognosis, while regular pulmonary function evaluation was associated with better survival. The INBUILD, ATS/ERS/JRS/ALAT 2022, and simplified PF criteria revealed similar prognostication.

7.
Front Bioeng Biotechnol ; 10: 925197, 2022.
Artículo en Inglés | MEDLINE | ID: mdl-35928949

RESUMEN

Sericin, a waste product of the silk textile industry, has favorable physicochemical and biological properties. In this study, we extracted a low molecular weight (MW) sericin (LMW-sericin; below 10 kDa) by a performing high-temperature and high-pressure method and confirmed the MW using matrix-assisted laser desorption ionization-time of flight and liquid chromatography-mass spectrometry. Furthermore, we determined its biological effects on macrophages and human adipose stem cells (hASCs) as cell models to investigate the biocompatibility, immunomodulation behavior, and potential signaling pathway-related wound healing via analyses of gene expression of focal adhesion and human cytokines and chemokines using quantitative real-time polymerase chain reaction and cytokine assay. LMW-sericin showed good biocompatibility both in macrophages and hASCs. Macrophages cultured with 0.1 mg/ml LMW-sericin displayed an improved inflammatory response shown by the upregulation of CXCL9, IL12A, BMP7, and IL10, which developed Th1 and Th2 balance. LMW-sericin also improved the differentiation of macrophages toward the M2 phenotype by significantly enhancing the expression of Arg-1, which is conducive to the repair of the inflammatory environment. Moreover, the gene expression of hASCs showed that LMW-sericin promoted the secretion of beneficial adhesion molecules that potentially activate the gene transcription of differentiation and migration in hASCs, as well as significantly enhanced the levels of PKCß1, RhoA, and RasGFR1 as fruitful molecules in wound healing. These findings provide insights into LMW-sericin application as a potential biomaterial for wound management.

8.
J Inflamm Res ; 15: 2255-2262, 2022.
Artículo en Inglés | MEDLINE | ID: mdl-35422651

RESUMEN

Objective: Krebs von den Lungen-6 (KL-6) is expressed on regenerating type II pneumocytes and has been recognized as biomarkers in interstitial lung disease (ILD). We aim to identify the role of the serum KL-6 level in patients with newly diagnosed Sjögren syndrome (SS), as well as the correlation between the immunoassays. Methods: Patients with newly diagnosed SS and receiving HRCT for clinical reason during follow-up were included. Baseline KL-6 level was measured via enzyme-linked immunosorbent assay (ELISA) and latex particle-enhanced turbidimetric immunoassay (LETIA). Results: Of the 39 patients, 21 (53.85%) developed interstitial lung disease (ILD) by the conclusion of the follow-up period. The median time to diagnosis of ILD was 2.24 years (IQR 1.15-4.34) in the ILD group. The median serum KL-6 level, measured using ELISA, was 1232 U/mL (IQR 937-2242) and 764.5 U/mL (IQR 503.25-1035.75) in the ILD group and the non-ILD group, respectively (p = 0.001). The median LETIA for serum KL-6 was 329 U/mL (IQR 235-619) and 245 U/mL (IQR 215.25-291) in the ILD group and the non-ILD group, respectively (p = 0.074). Conclusion: Serum KL-6 levels were higher in newly diagnosed SS patients with ILD diagnosis during follow-up. Thus, the serum KL-6 level can serve as a valuable biomarker to identify hidden ILD in patients with newly diagnosed SS patients. However, the immunoassay procedure may influence the efficacy of the prediction and its clinical association.

9.
Respir Med ; 187: 106579, 2021 10.
Artículo en Inglés | MEDLINE | ID: mdl-34438351

RESUMEN

BACKGROUND: Connective tissue disease associated interstitial lung disease (CTD-ILD) is associated with decreased quality of life and high mortality risk. Outcome and treatment response is unpredictable. This study aimed to identify clinical predictors for CTD-ILD with poor outcome. METHODS: We performed a retrospective single centre cohort study in outpatients with CTD-ILD seen between 2004 and 2018. Clinical and biochemical data, pulmonary function tests (PFT) and high-resolution computed tomography (HRCT) results were analysed. Overall survival and progressive fibrosing ILD (PF-ILD, defined as a significant deterioration of PFT or HRCT) after two years of follow-up were assessed. RESULTS: In total, 150 patients with CTD-ILD were included. Thirty (20%) deaths occurred during a median follow-up of 40 months (IQR 27.3-60.8), which were attributed to pulmonary infection in six (4%), respiratory failure due to PF-ILD in ten (7%) and due to other causes in fourteen patients. PF-ILD occurred in 76 (50.7%) patients and was associated with poor overall survival (adjusted HR 5.73, 95%CI 1.17-28.11). Age, smoking, C-reactive protein, and steroid-use were independently associated with increased mortality risk as well. Furthermore, patients with diabetes mellitus (adjusted OR 4.52, 95%CI 1.10-18.51), steroid-use (adjusted OR 2.26, 95%CI 1.04-4.93), and a fibrotic HRCT pattern at baseline (adjusted OR 3.11, 95%CI 1.15-8.38) had a higher risk of PF-ILD. CONCLUSION: PF-ILD is associated with increased mortality in patients with CTD-ILD. Patients with a fibrotic HRCT pattern at baseline, diabetes mellitus and steroid-use have a higher risk of developing PF-ILD.


Asunto(s)
Enfermedades del Tejido Conjuntivo/etiología , Enfermedades del Tejido Conjuntivo/patología , Enfermedades Pulmonares Intersticiales/etiología , Enfermedades Pulmonares Intersticiales/patología , Factores de Edad , Anciano , Proteína C-Reactiva , Enfermedades del Tejido Conjuntivo/diagnóstico , Enfermedades del Tejido Conjuntivo/mortalidad , Diabetes Mellitus , Progresión de la Enfermedad , Femenino , Fibrosis , Estudios de Seguimiento , Predicción , Humanos , Enfermedades Pulmonares Intersticiales/diagnóstico , Enfermedades Pulmonares Intersticiales/mortalidad , Masculino , Persona de Mediana Edad , Calidad de Vida , Pruebas de Función Respiratoria , Estudios Retrospectivos , Riesgo , Fumar , Tomografía Computarizada por Rayos X
10.
Sci Rep ; 10(1): 6294, 2020 04 14.
Artículo en Inglés | MEDLINE | ID: mdl-32286343

RESUMEN

Dengue virus (DENV) infections may cause life-threatening dengue hemorrhagic fever (DHF). Suppressed protective immunity was shown in these patients. Although several hypotheses have been formulated, the mechanism of DENV-induced immunosuppression remains unclear. Previously, we found that cross-reactive antibodies against tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) receptor 1 (death receptor 4 [DR4]) were elicited in DHF patients, and that anti-DR4 autoantibody fractions were elicited by nonstructural protein 1 (NS1) immunizations in experimental mice. In this study, we found that anti-DR4 antibodies could suppress B lymphocyte function in vitro and in vivo. Treatment with the anti-DR4 immunoglobulin (Ig) induced caspase-dependent cell death in immortalized B lymphocyte Raji cells in vitro. Anti-DR4 Igs elicited by NS1 and DR4 immunizations markedly suppressed mouse spleen transitional T2 B (IgM+IgD+), bone marrow pre-pro-B (B220+CD43+), pre-B (B220+CD43-), and mature B cell (B220+IgD+) subsets in mice. Furthermore, functional analysis revealed that the pre-elicitation of anti-NS1 and anti-DR4 Ig titers suppressed subsequently neutralizing antibody production by immunization with DENV envelop protein. Our data suggest that the elicitation of anti-DR4 titers through DENV NS1 immunization plays a suppressive role in humoral immunity in mice.


Asunto(s)
Anticuerpos Antivirales/inmunología , Inmunidad Humoral , Receptores del Ligando Inductor de Apoptosis Relacionado con TNF/inmunología , Dengue Grave/inmunología , Proteínas no Estructurales Virales/inmunología , Animales , Autoanticuerpos/sangre , Células Cultivadas , Virus del Dengue/inmunología , Humanos , Inmunización , Ratones , Ratones Endogámicos C57BL
11.
Medicine (Baltimore) ; 97(20): e10798, 2018 May.
Artículo en Inglés | MEDLINE | ID: mdl-29768374

RESUMEN

RATIONALE: Thromboangiitis obliterans (TAOs, or Buerger's disease) present as a non-atherosclerotic segmental occlusive vasculitis within medium- and small-sized blood vessels. TAO frequently occurs in young adults and is associated with cigarette smoking. At present, there are no accurately defined treatments for TAO. PATIENT CONCERNS: A 34-year-old Asian woman with a 20-year history of heavy cigarette smoking and recurrent, small, and self-limited lower limb ulcerations since adolescence, presented with persisting unhealed ulcerations on both ankles for 6 months. Her wound healing response was poor following the 2-month administration of colchicine, prednisolone, hydroxychloroquine, and mycophenolic acid. DIAGNOSIS: The patient was diagnosed with TAO with hyperimmunoglobulin E and refractory ulcerations on her ankles. INTERVENTIONS: The patient received monthly omalizumab (300 mg) and previous medications for 2 months and shifted to omalizumab and colchicine without mycophenolic acid and hydroxychloroquine because of onychomadesis, which was considered to be a possible adverse drug reaction. OUTCOMES: The wounds healed almost completely. The administration of omalizumab and colchicine will be continued until they the wounds are fully healed. LESSONS: Mycophenolic acid has a limited function in TAO treatment, especially in cases of refractory skin ulcerations. Omalizumab can be a valuable treatment option for patients with TAO and hyperimmunoglobulin E.


Asunto(s)
Colchicina/uso terapéutico , Fármacos Dermatológicos/uso terapéutico , Omalizumab/uso terapéutico , Úlcera Cutánea/tratamiento farmacológico , Úlcera Cutánea/etiología , Tromboangitis Obliterante/complicaciones , Adulto , Tobillo , Femenino , Humanos , Inmunoglobulina E/sangre , Inmunoglobulina E/efectos de los fármacos , Úlcera Cutánea/inmunología , Fumar/efectos adversos , Tromboangitis Obliterante/inmunología , Tromboangitis Obliterante/fisiopatología , Cicatrización de Heridas
12.
Am J Med Sci ; 355(2): 153-161, 2018 02.
Artículo en Inglés | MEDLINE | ID: mdl-29406043

RESUMEN

BACKGROUND: Fibromyalgia is a syndrome of chronic pain and other symptoms and is associated with patient discomfort and other diseases. This nationwide matched-cohort population-based study aimed to investigate the association between fibromyalgia and the risk of developing dementia, and to clarify the association between fibromyalgia and dementia. MATERIALS AND METHODS: A total of 41,612 patients of age ≥50 years with newly diagnosed fibromyalgia between January 1, and December 31, 2000 were selected from the National Health Insurance Research Database of Taiwan, along with 124,836 controls matched for sex and age. After adjusting for any confounding factors, Fine and Gray competing risk analysis was used to compare the risk of developing dementia during the 10 years of follow-up. RESULTS: Of the study subjects, 1,704 from 41,612 fibromyalgia patients (21.23 per 1,000 person-years) developed dementia when compared to 4,419 from 124,836 controls (18.94 per 1,000 person-years). Fine and Gray competing risk analysis revealed that the study subjects were more likely to develop dementia (hazard ratio: 2.29, 95% CI: 2.16-2.42; P < 0.001). After adjusting for sex, age, monthly income, urbanization level, geographic region of residence and comorbidities the hazard ratio was 2.77 (95% CI: 2.61-2.95, P < 0.001). Fibromyalgia was associated with increased risk of all types of dementia in this study. CONCLUSIONS: The study subjects with fibromyalgia had a 2.77-fold risk of dementia in comparison to the control group. Therefore, further studies are needed to elucidate the underlying mechanisms of the association between fibromyalgia and the risk of dementia.


Asunto(s)
Bases de Datos Factuales , Demencia/epidemiología , Demencia/etiología , Fibromialgia/complicaciones , Fibromialgia/epidemiología , Factores de Edad , Anciano , Anciano de 80 o más Años , Demencia/fisiopatología , Femenino , Fibromialgia/fisiopatología , Estudios de Seguimiento , Humanos , Masculino , Persona de Mediana Edad , Factores de Riesgo , Factores Sexuales , Factores Socioeconómicos , Taiwán/epidemiología
13.
Oncotarget ; 8(30): 50098-50108, 2017 Jul 25.
Artículo en Inglés | MEDLINE | ID: mdl-28177920

RESUMEN

Sjögren syndrome (SS) is commonly known to be correlated with lymphoma. This study included 16,396 individuals in the SS cohort and 65,584 individuals in the non-SS cohort, all of whom were enrolled in the Taiwan National Health Insurance database between 2000 and 2010. We evaluated the risk factors of non-Hodgkin's lymphoma (NHL) in the primary SS cohort by applying a Cox multivariable proportional-hazards model. We increased the correlation of patients with SS and NHL, with an adjusted HR of 4.314 (95% CI 2.784 - 6.685). Of the 16,396 SS patients, 66 individuals had salivary gland slices without NHL development, while the other 16,330 individuals that did not have salivary gland slices revealed 30 individuals that developed NHL. Of the 16,396 SS patients, 128 individuals underwent immunomodulator agent therapy (including hydroxychloroquine, azathioprine, cyclosporine, methotrexate, and rituximab) without NHL development. None of the 30 individuals that developed NHL from SS received immunomodulator agents. We found that patients with SS were at an increased risk of developing NHL, with the most common NHL subgroup being diffused large B-cell lymphoma. SS patients who were candidates for salivary gland slices or immunomodulator agents were associated with a lower risk of developing lymphoma over time. We recommend that patients at a higher risk upon diagnosis of SS receive close follow-up and aggressive treatment.


Asunto(s)
Biomarcadores/metabolismo , Linfoma/etiología , Síndrome de Sjögren/complicaciones , Estudios de Cohortes , Femenino , Humanos , Linfoma/patología , Masculino , Persona de Mediana Edad , Estudios Retrospectivos , Factores de Riesgo , Síndrome de Sjögren/patología
14.
Sci Rep ; 6: 37174, 2016 11 17.
Artículo en Inglés | MEDLINE | ID: mdl-27853187

RESUMEN

A general solvent-dependent protocol directly influencing the oxygen reduction reaction (ORR) in metal oxide/graphene nanohybrids has been demonstrated. We conducted the two-step synthesis of cobalt oxide/N-doped graphene nanohybrids (CNG) with solvents of water, ethanol, and dimethylformamide (DMF), representing tree typical categories of aqueous, polar organic, and organic N-containing solvents commonly adopted for graphene nanocomposites preparation. The superior ORR performance of the DMF-hybrids can be attributed to the high nitrogen-doping, aggregation-free hybridization, and unique graphene porous structures. As DMF is the more effective N-source, the spectroscopic results support a catalytic nitrogenation potentially mediated by cobalt-DMF coordination complexes. The wide-distribution of porosity (covering micro-, meso-, to macro-pore) and micron-void assembly of graphene may further enhance the diffusion kinetics for ORR. As the results, CNG by DMF-synthesis exhibits the high ORR activities close to Pt/C (i.e. only 8 mV difference of half-wave potential with electron transfer number of 3.96) with the better durability in the alkaline condition. Additional graphene hybrids comprised of iron and manganese oxides also show the superior ORR activities by DMF-synthesis, confirming the general solvent-dependent protocol to achieve enhanced ORR activities.

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