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1.
J Hepatocell Carcinoma ; 10: 1257-1266, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37538403

RESUMO

Background: At present, it is not known whether targeting plus immunotherapy combined with transarterial chemoembolization (TACE) can improve the efficacy of hepatocellular carcinoma (HCC). The aim of this retrospective experiment was to explore the difference in clinical efficacy between antiangiogenic drugs plus PD-1 inhibitors combined with and without TACE. Methods: Clinical data of 145 patients with HCC who received anti-angiogenesis therapy plus PD-1 inhibitor combined with TACE (TACE-P-T) (n = 62) or anti-angiogenesis therapy combined with PD-1 inhibitor (P-T) (n = 83) in China from October 2018 to December 2022 were collected and reviewed. We used propensity matching (PSM) to create two groups with comparable baseline scores, compared their median survival time (mOS) and median progression-free survival time (mPFS), and performed subgroup analysis. Results: Before PSM, the mOS and mPFS of patients were 20.3 and 5.0 months in the triple therapy group and 13.6 and 7.4 months in the control group, respectively. After PSM, the mOS and mPFS of patients were 19.7 and 6.6 months in the triple treatment group and 10.5 and 3.7 months in the control group, respectively. Therefore, the TACE-P-T group showed better survival outcomes than P-T. In the subgroup analysis, compared with the control group, the mOS was 10.7 vs 20.3 months in the alpha fetoprotein (AFP) (≥ 400ng/mL/<400ng/mL) group, 29.3 vs 7.4 months in the alkaline phosphatase (ALP) (≥ 125u/L/< 125u/L) group and 10.5 vs 20.0 months in the Portal vein invasion (PVTT) group. Conclusion: Antiangiogenic therapy combined with PD-1 inhibitors combined with TACE has significant survival benefits for HCC patients.

2.
J Cancer Res Clin Oncol ; 149(15): 14271-14282, 2023 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-37561208

RESUMO

INTRODUCTION: The aim of this study was to investigate the role of thymidine kinase 1 (TK1) levels in hepatocellular carcinoma (HCC) prognosis and to develop a nomogram for predicting HCC prognosis. METHOD: In this study, 1066 HCC patients were enrolled between August 2018 and April 2022. TK1 levels were measured within one week before enrollment, and the relationship with HCC prognosis was evaluated. Next, all patients were randomly assigned to the training set (70%, n = 746) and the validation set (30%, n = 320). We used multivariate Cox analysis to find independent prognostic factors in the training set to construct a nomogram. The predictive power of the nomogram was assessed using receiver operating characteristic (ROC) curves, calibration curves, and decision curve analysis (DCA). The optimal critical value of TK1 was determined as 2.35 U/L using X-tile software. RESULT: Before and after propensity score matching (PSM), the median overall survival (mOS) of the low-TK1 group (< 2.35 U/L) remained significantly longer than that of the high-TK1 group (≥ 2.35 U/L) (48.1 vs 16.5 months, p < 0.001; 75.7 vs 19.8 months, p = 0.001). Moreover, multivariate Cox analysis showed that the low TK1 level was an independent positive prognostic indicator. Additionally, the area under the ROC curve for predicting the 1-year, 2-year, and 3-year survival rates was 0.770, 0.758, and 0.805, respectively. CONCLUSIONS: TK1 could serve as a prognostic marker for HCC. In addition, the nomogram showed good predictive capability for HCC prognosis.

3.
Histochem Cell Biol ; 160(1): 11-25, 2023 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-37014442

RESUMO

Experimental autoimmune encephalomyelitis (EAE) is a classical animal model of human multiple sclerosis (MS) that is most commonly used to study the neuropathology and therapeutic effects of the disease. Telocytes (TCs) are a specialized type of interstitial or mesenchymal cell first identified by Popescu in various tissues and organs. However, the existence, distribution and role of CD34+ stromal cells (SCs)/TCs in the EAE-induced mouse spleen remain to be elucidated. We conducted immunohistochemistry, immunofluorescence (double staining for CD34 and c-kit, vimentin, F4/80, CD163, Nanog, Sca-1, CD31 or tryptase) and transmission electron microscopy experiments to investigate the existence, distribution and role of CD34+ SCs/TCs in the EAE-induced mouse spleen. Interestingly, immunohistochemistry, double-immunofluorescence, and transmission electron microscopy results revealed that CD34+ SCs/TCs were significantly upregulated in the EAE mouse spleen. Immunohistochemical or double-immunofluorescence staining of CD34+ SCs/TCs showed positive expression for CD34, c-kit, vimentin, CD34/vimentin, c-kit/vimentin and CD34/c-kit, and negative expression for CD31 and tryptase. Transmission electron microscopy (TEM) results demonstrated that CD34+ SCs/TCs established close connections with lymphocytes, reticular cells, macrophages, endothelial cells and erythrocytes. Furthermore, we also found that M1 (F4/80) or M2 (CD163) macrophages, and haematopoietic, pluripotent stem cells were markedly increased in EAE mice. Our results suggest that CD34+ SCs/TCs are abundant and may play a contributing role in modulating the immune response, recruiting macrophages and proliferation of haematopoietic and pluripotent stem cells following injury to promote tissue repair and regeneration in EAE mouse spleens. This suggests that their transplantation combined with stem cells might represent a promising therapeutic target for the treatment and prevention of multiple autoimmune and chronic inflammatory disorders.


Assuntos
Encefalomielite Autoimune Experimental , Células-Tronco Pluripotentes , Telócitos , Animais , Camundongos , Antígenos CD34/metabolismo , Moléculas de Adesão Celular/metabolismo , Encefalomielite Autoimune Experimental/patologia , Células Endoteliais/metabolismo , Células-Tronco Pluripotentes/metabolismo , Baço , Células Estromais/metabolismo , Telócitos/metabolismo , Telócitos/patologia , Triptases/metabolismo , Vimentina/metabolismo
4.
Front Immunol ; 14: 1298683, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-38162672

RESUMO

Immunotherapy, notably chimeric antigen receptor (CAR) modified natural killer (NK) cell therapy, has shown exciting promise in the treatment of hematologic malignancies due to its unique advantages including fewer side effects, diverse activation mechanisms, and wide availability. However, CAR-NK cell therapies have demonstrated limited efficacy against solid tumors, primarily due to challenges posed by the solid tumor microenvironment. In contrast, radiotherapy, a well-established treatment modality, has been proven to modulate the tumor microenvironment and facilitate immune cell infiltration. With these observations, we hypothesize that a novel therapeutic strategy integrating CAR-NK cell therapy with radiotherapy could enhance the ability to treat solid tumors. This hypothesis aims to address the obstacles CAR-NK cell therapies face within the solid tumor microenvironment and explore the potential efficacy of their combination with radiotherapy. By capitalizing on the synergistic advantages of CAR-NK cell therapy and radiotherapy, we posit that this could lead to improved prognoses for patients with solid tumors.


Assuntos
Neoplasias , Receptores de Antígenos Quiméricos , Humanos , Células Matadoras Naturais , Imunoterapia Adotiva , Neoplasias/radioterapia , Imunoterapia , Microambiente Tumoral
5.
Nat Mater ; 21(7): 804-810, 2022 07.
Artigo em Inglês | MEDLINE | ID: mdl-35379980

RESUMO

The hydroxide exchange membrane fuel cell (HEMFC) is a promising energy conversion technology but is limited by the need for platinum group metal (PGM) electrocatalysts, especially for the hydrogen oxidation reaction (HOR). Here we report a Ni-based HOR catalyst that exhibits an electrochemical surface area-normalized exchange current density of 70 µA cm-2, the highest among PGM-free catalysts. The catalyst comprises Ni nanoparticles embedded in a nitrogen-doped carbon support. According to X-ray and ultraviolet photoelectron spectroscopy as well as H2 chemisorption data, the electronic interaction between the Ni nanoparticles and the support leads to balanced hydrogen and hydroxide binding energies, which are the likely origin of the catalyst's high activity. PGM-free HEMFCs employing this Ni-based HOR catalyst give a peak power density of 488 mW cm-2, up to 6.4 times higher than previous best-performing analogous HEMFCs. This work demonstrates the feasibility of efficient PGM-free HEMFCs.


Assuntos
Níquel , Platina , Hidrogênio/química , Hidróxidos , Níquel/química , Oxirredução , Platina/química
6.
Stem Cell Res Ther ; 13(1): 155, 2022 04 11.
Artigo em Inglês | MEDLINE | ID: mdl-35410627

RESUMO

BACKGROUND: Immunosuppressive properties grant mesenchymal stromal cells (MSCs) promising potential for treating autoimmune diseases. As autologous MSCs suffer from limited availability, the readily available allogeneic MSCs isolated from menstrual blood (MB-MSCs) donated by young, healthy individuals offer great potential. Here, we evaluate the therapeutic potential of MB-MSCs as ready-to-use allo-MSCs in multiple sclerosis, an autoimmune disease developed by the activation of myelin sheath-reactive Th1 and Th17 cells, by application in its animal model experimental autoimmune encephalomyelitis (EAE). METHODS: We assessed the therapeutic effect of MB-MSCs transplanted via either intravenous (i.v.) or intraperitoneal (i.p.) route in EAE in comparison with umbilical cord-derived MSCs (UC-MSCs). We used histology to assess myelin sheath integrity and infiltrated immune cells in CNS and flow cytometry to evaluate EAE-associated inflammatory T cells and antigen-presenting cells in lymphoid organs. RESULTS: We observed disease-ameliorating effects of MB-MSCs when transplanted at various stages of EAE (day - 1, 6, 10, and 19), via either i.v. or i.p. route, with a potency comparable to UC-MSCs. We observed reduced Th1 and Th17 cell responses in mice that had received MB-MSCs via either i.v. or i.p. injection. The repressed Th1 and Th17 cell responses were associated with a reduced frequency of plasmacytoid dendritic cells (pDCs) and a suppressed co-stimulatory capacity of pDCs, cDCs, and B cells. CONCLUSIONS: Our data demonstrate that the readily available MB-MSCs significantly reduced the disease severity of EAE upon transplantation. Thus, they have the potential to be developed as ready-to-use allo-MSCs in MS-related inflammation.


Assuntos
Encefalomielite Autoimune Experimental , Transplante de Células-Tronco Mesenquimais , Células-Tronco Mesenquimais , Animais , Diferenciação Celular , Ativação Linfocitária , Camundongos , Camundongos Endogâmicos C57BL , Células Th17
7.
J Cell Physiol ; 236(2): 1454-1468, 2021 02.
Artigo em Inglês | MEDLINE | ID: mdl-32691413

RESUMO

Diabetic nephropathy (DN) is acknowledged as a serious chronic complication of diabetes mellitus. Nevertheless, its pathogenesis is complicated and unclear. Thus, in this study, the role of miR-27a-3p-prohibitin/TMBIM6 signaling axis in the progression of DN was elucidated. Type 2 diabetic db/db mice and high glucose (HG)-challenged HK-2 cells were used as in vivo and in vitro models. Our results showed that miR-27a-3p was upregulated and prohibitin or transmembrane BAX inhibitor motif containing 6 (TMBIM6) was downregulated in the kidney tissues of db/db mice and HG-treated HK-2 cells. Silencing miR-27a-3p enhanced the expression of prohibitin and TMBIM6 in the kidney tissues and HK-2 cells. Inhibition of miR-27a-3p improved functional injury, as evidenced by decreased blood glucose, urinary albumin, serum creatinine, and blood urea nitrogen levels. MiR-27a-3p silencing ameliorated renal fibrosis, reflected by reduced profibrogenic genes (e.g., transforming growth factor ß1, fibronectin, collagen I and III, and α-smooth muscle actin). Furthermore, inhibition of miR-27a-3p relieved mitochondrial dysfunction in the kidney of db/db mice, including upregulation of mitochondrial membrane potential, complex I and III activities, adenosine triphosphate, and mitochondrial cytochrome C, as well as suppressing reactive oxygen species production. In addition, miR-27a-3p silencing attenuated endoplasmic reticulum (ER) stress, reflected by reduced expression of p-IRE1α, p-eIF2α, XBP1s, and CHOP. Mechanically, we identified prohibitin and TMBIM6 as direct targets of miR-27a-3p. Inhibition of miR-27a-3p protected HG-treated HK-2 cells from apoptosis, extracellular matrix accumulation, mitochondrial dysfunction, and ER stress by regulating prohibitin or TMBIM6. Taken together, we reveal that miR-27a-3p-prohibitin/TMBIM6 signaling axis regulates the progression of DN, which can be a potential therapeutic target.


Assuntos
Nefropatias Diabéticas/genética , Rim/metabolismo , Proteínas de Membrana/genética , MicroRNAs/genética , Animais , Apoptose/genética , Nefropatias Diabéticas/metabolismo , Nefropatias Diabéticas/patologia , Estresse do Retículo Endoplasmático/genética , Fibrose/genética , Fibrose/metabolismo , Fibrose/patologia , Glucose , Humanos , Rim/patologia , Camundongos , Camundongos Endogâmicos NOD , Mitocôndrias/genética , Podócitos/metabolismo , Podócitos/patologia
8.
Drug Des Devel Ther ; 14: 2381-2392, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32606605

RESUMO

PURPOSE: Patients with type 1 diabetes (T1D) are associated with a high risk of multiple complications, so the development of T1D treatment is urgently needed. This study was set out to explore the molecular mechanism of metformin in the treatment of T1D insulin resistance. PATIENTS AND METHODS: Subcutaneous adipose tissues were collected from 68 T1D patients and 51 healthy controls. Insulin resistance model rats and cells were constructed and treated with metformin respectively. Western blot was used to detect p53 and RAP2A protein levels, and qPCR was utilized to measure p53 and RAP2A mRNA levels. SiRNA and RAP2A siRNA vectors were constructed to observe their effects on insulin resistance model cells. RESULTS: In T1D, p53 was up-regulated, while RAP2A was down-regulated. Metformin could effectively improve insulin resistance and inflammatory response while down-regulating p53 and up-regulating RAP2A. P53 induced insulin resistance and inflammatory response by inhibiting RAP2A and promoted apoptosis. CONCLUSION: Metformin improves T1D insulin resistance and inflammatory response through p53/RAP2A pathway, and the regulation of p53/RAP2A pathway is conducive to improving the efficacy of metformin in the treatment of insulin resistance.


Assuntos
Diabetes Mellitus Tipo 1/tratamento farmacológico , Hipoglicemiantes/farmacologia , Resistência à Insulina , Metformina/farmacologia , Proteína Supressora de Tumor p53/biossíntese , Proteínas rap de Ligação ao GTP/metabolismo , Células 3T3-L1 , Animais , Diabetes Mellitus Tipo 1/metabolismo , Feminino , Humanos , Masculino , Camundongos , Pessoa de Meia-Idade , RNA Mensageiro/efeitos dos fármacos , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Proteína Supressora de Tumor p53/genética , Proteína Supressora de Tumor p53/metabolismo
9.
J Colloid Interface Sci ; 569: 298-306, 2020 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-32120137

RESUMO

Wire-shaped supercapacitors (WSC) have attracted tremendous attention for powering portable electronic devices. However, previously reported WSC suffered from a complicated fabrication process and high cost. The objective of this study is to develop a facile and scalable process for the fabrication of high energy density WSC. We coupled the wet-spinning assembly with an in situ electrodeposition technique to prepare carbon nanotube (CNT)-based composite fibers. The charge balance between the electrodes was realized by controlling the deposition time of the pseudocapacitive materials. A wire-shaped asymmetric supercapacitor (WASC) was fabricated by twisting MnO2/CNT fiber cathode and PPy/CNT fiber anode with LiCl/PVA electrolyte. The flexible MnO2/CNT//PPy/CNT WASC operated in a broadened voltage range of 0-1.8 V exhibited a high capacitance of 17.5F cm-3 (10.7F g-1). In addition, it delivered a maximum energy and power densities of 7.88 mWh cm-3 (4.82 Wh kg-1) and 2.26 W cm-3 (1382 W kg-1), respectively. The WASC device demonstrated satisfactory cycling stability with 86% capacitance retention, and its Coulombic efficiency remained at 96% after 5000 charge-discharge cycles. The contributions of the diffusion-controlled insertion and the surface capacitive effect were theoretically quantified to investigate the energy storage mechanism. The fabrication approaches hold potential for the construction of cost-effective and high-performance WSC.

10.
Metab Brain Dis ; 35(2): 373-383, 2020 02.
Artigo em Inglês | MEDLINE | ID: mdl-31916204

RESUMO

Postoperative cognitive dysfunction (POCD) is a common neurological disease affecting the elderly patients after surgery. Unfortunately, no effective treatment for this disease has been discovered. Edaravone, a clinical-used free radical scavenger, at 3 mg/kg has been reported to prevent neuroinflammation induced by the combination of surgery and lipopolysaccharide in adult rodents. However, we found that edaravone at such low concentration could not inhibit POCD in aged mice. Instead, edaravone at 33.2 mg/kg significantly prevented recognition and spatial cognitive dysfunctions in 14 month aged mice after abdominal surgery under general anesthesia with isoflurane. Furthermore, edaravone significantly prevented the increase of tumor necrosis factor-α (TNF-α), interleukin-1ß (IL-1ß) and interleukin-6 (IL-6) induced by abdominal surgery in aged mice. Edaravone could also decrease glial fibrillary acidic protein (GFAP) and ionized calcium binding adaptor molecule-1 (Iba-1) positive areas in the hippocampal regions of surgery mice, suggesting that edaravone might inhibit surgery-induced over-activation of microglia and astrocytes. Moreover, edaravone substantially increased the expression of PSD-95 and pSer9-glycogen synthase kinase-3ß (pSer9-GSK3ß) as demonstrated by Western blotting assay. Furthermore, the activity of acetylcholinesterase (AChE) is decreased in the mice in edaravone group. All these results suggested that edaravone at high concentrations could inhibit surgery-induced cognitive impairments in aged animals, possibly via the attenuation of neuroinflammation, the increase of synaptic proteins, and the elevation of cholinergic transmission, providing a further support that edaravone might be developed as a treatment of POCD.


Assuntos
Envelhecimento/efeitos dos fármacos , Anestesia Geral/efeitos adversos , Disfunção Cognitiva/prevenção & controle , Edaravone/administração & dosagem , Fármacos Neuroprotetores/administração & dosagem , Complicações Cognitivas Pós-Operatórias/prevenção & controle , Parede Abdominal/cirurgia , Envelhecimento/psicologia , Animais , Disfunção Cognitiva/etiologia , Disfunção Cognitiva/psicologia , Relação Dose-Resposta a Droga , Masculino , Camundongos , Camundongos Endogâmicos ICR , Complicações Cognitivas Pós-Operatórias/etiologia , Complicações Cognitivas Pós-Operatórias/psicologia
11.
Bioorg Med Chem Lett ; 29(13): 1593-1596, 2019 07 01.
Artigo em Inglês | MEDLINE | ID: mdl-31078410

RESUMO

Two new γ-lactones, aspergilactones A (1) and B (2), were discovered along with two known compounds, annularin A (3) and pericoterpenoid A (4), from a culture of the sponge-associated fungus Aspergillus sp. LS45. The planar structures of 1-4 were characterized using comprehensive spectroscopic methods and comparison with literature data. The absolute configurations of 1 and 2 were determined by comparison of electronic circular dichroism (ECD) spectroscopic and optical rotation data with those of known analogues as well as calculated ECD analysis. Compounds 1-4 were tested in a variety of bioassays, and both 1 and 4 exhibited significant inhibition against the lateral root growth of Arabidopsis thaliana Columbia-0 at a concentration of 100 µM. In addition, the in vitro cytotoxic activities of 1-4 against six human cancer cell lines CCRF-CEM, K562, BGC823, AGS, HCT-116 and MDA-MB-231 were evaluated. Compound 4 showed moderate inhibitory effects on CCRF-CEM and K562 cancer cell lines with IC50 values of 13.8 ±â€¯1.6 and 12.9 ±â€¯2.5 µM, respectively. However, compounds 1-4 did not show any notable AChE inhibitory activity in vitro.


Assuntos
Aspergillus/química , Fungos/química , Reguladores de Crescimento de Plantas/química
12.
IUBMB Life ; 71(1): 28-40, 2019 01.
Artigo em Inglês | MEDLINE | ID: mdl-30325582

RESUMO

Papillary thyroid carcinoma is one of the most fatal malignant endocrine tumors, and the prognosis remains poor because of the lack of effective therapeutic targets. In this study, we demonstrated that the level of miR-199b-5p was markedly downregulated in papillary thyroid carcinoma. The ectopic expression level of miR-199b-5p in papillary thyroid carcinoma cell B-CPAP could inhibit growth, migration, and invasion as well as epithelial-mesenchymal transition (EMT) and decreased cell metastasis in vivo, but silencing miR-199b-5p caused a contradictory outcome. Additionally, Stonin 2 (STON2) was identified as a direct target gene of miR-199b-5p. Consistent with the downregulation of miR-199b-5p, the overexpression of STON2 induced the growth, migration and invasion of B-CPAP cells. It was also demonstrated that miR-199b-5p suppressed papillary thyroid carcinoma cell aggressiveness by targeting STON2. Furthermore, the overexpression of miR-199b-5p inhibited cell proliferation, promoted apoptosis, and increased the chemo-sensitivity of thyroid carcinoma B-CPAP cells toward the chemotherapy drug paclitaxel. Finally, in vivo experiments further demonstrated that miR-199b-5p suppressed tumor growth in nude mice. Thus, this study revealed that miR-199b-5p functions as antioncogene miRNA in papillary thyroid carcinoma cells and that the miR-199b-5p/STON2 axis might be a potential treatment option for papillary thyroid carcinoma. © 2018 IUBMB Life, 71(1):28-40, 2019.


Assuntos
Proteínas Adaptadoras de Transporte Vesicular/genética , MicroRNAs/genética , Prognóstico , Câncer Papilífero da Tireoide/genética , Animais , Linhagem Celular Tumoral , Movimento Celular/genética , Proliferação de Células/genética , Transição Epitelial-Mesenquimal/genética , Regulação Neoplásica da Expressão Gênica , Xenoenxertos , Humanos , Camundongos , Paclitaxel/farmacologia , Câncer Papilífero da Tireoide/tratamento farmacológico , Câncer Papilífero da Tireoide/patologia
13.
Angew Chem Int Ed Engl ; 56(36): 10735-10739, 2017 08 28.
Artigo em Inglês | MEDLINE | ID: mdl-28675612

RESUMO

Gaseous HCl as a by-product is often produced from chlorination processes using Cl2 gas. Onsite Cl2 regeneration from HCl is highly desirable as it eliminates the need to buy new Cl2 and dispose HCl waste. A gaseous HCl electrolysis with Fe3+ /Fe2+ redox-mediated cathode is demonstrated for Cl2 regeneration. HCl is oxidized to generate Cl2 and protons in the anode while Fe3+ is reduced to Fe2+ in the cathode. Simultaneously Fe3+ is regenerated by chemical oxidation of Fe2+ by oxygen (air) that also produces water. A low operational voltage and high coulombic efficiency are achieved by using a novel composite porous membrane and hydrophobic anode. Specifically, a cell voltage of only 0.64 V is needed at the typical current density of 4 kA m-2 , leading to a low energy consumption of 483 kWh per ton of Cl2 (124 kJ molCl2 -1 ) which is about 50-55 % of state-of-the-art HCl electrolysis processes.

14.
Nat Commun ; 7: 10141, 2016 Jan 14.
Artigo em Inglês | MEDLINE | ID: mdl-26762466

RESUMO

The development of a low-cost, high-performance platinum-group-metal-free hydroxide exchange membrane fuel cell is hindered by the lack of a hydrogen oxidation reaction catalyst at the anode. Here we report that a composite catalyst, nickel nanoparticles supported on nitrogen-doped carbon nanotubes, has hydrogen oxidation activity similar to platinum-group metals in alkaline electrolyte. Although nitrogen-doped carbon nanotubes are a very poor hydrogen oxidation catalyst, as a support, it increases the catalytic performance of nickel nanoparticles by a factor of 33 (mass activity) or 21 (exchange current density) relative to unsupported nickel nanoparticles. Density functional theory calculations indicate that the nitrogen-doped support stabilizes the nanoparticle against reconstruction, while nitrogen located at the edge of the nanoparticle tunes local adsorption sites by affecting the d-orbitals of nickel. Owing to its high activity and low cost, our catalyst shows significant potential for use in low-cost, high-performance fuel cells.

15.
J Am Chem Soc ; 136(19): 7077-84, 2014 May 14.
Artigo em Inglês | MEDLINE | ID: mdl-24761994

RESUMO

Electrochemical water splitting is a clean technology that can store the intermittent renewable wind and solar energy in H2 fuels. However, large-scale H2 production is greatly hindered by the sluggish oxygen evolution reaction (OER) kinetics at the anode of a water electrolyzer. Although many OER electrocatalysts have been developed to negotiate this difficult reaction, substantial progresses in the design of cheap, robust, and efficient catalysts are still required and have been considered a huge challenge. Herein, we report the simple synthesis and use of α-Ni(OH)2 nanocrystals as a remarkably active and stable OER catalyst in alkaline media. We found the highly nanostructured α-Ni(OH)2 catalyst afforded a current density of 10 mA cm(-2) at a small overpotential of a mere 0.331 V and a small Tafel slope of ~42 mV/decade, comparing favorably with the state-of-the-art RuO2 catalyst. This α-Ni(OH)2 catalyst also presents outstanding durability under harsh OER cycling conditions, and its stability is much better than that of RuO2. Additionally, by comparing the performance of α-Ni(OH)2 with two kinds of ß-Ni(OH)2, all synthesized in the same system, we experimentally demonstrate that α-Ni(OH)2 effects more efficient OER catalysis. These results suggest the possibility for the development of effective and robust OER electrocatalysts by using cheap and easily prepared α-Ni(OH)2 to replace the expensive commercial catalysts such as RuO2 or IrO2.

16.
Langmuir ; 26(15): 12605-13, 2010 Aug 03.
Artigo em Inglês | MEDLINE | ID: mdl-20590135

RESUMO

The impact of surface roughness of bare and zeolite ZSM-5 coated stainless steel and aluminum alloy on colloid deposition has been investigated using a parallel plate flow chamber system in an aqueous environment. The metals were systematically polished to alter the surface roughness from nanoscale to microscale, with the subsequent surface roughness of both the bare and coated surfaces varying from 11.2 to 706 nm. The stainless steel and aluminum alloy surfaces are extensively characterized, both as bare and as coated surfaces. Experimental results suggest that ZSM-5 coating and surface roughness have a pronounced impact on the kinetics of the colloid deposition. The ZSM-5 coating reduced colloid adhesion compared to the corresponding bare metal surface. In general, the greater surface roughness of like samples resulted in higher colloid deposition. Primarily, this is due to greater surface roughness inducing less reduction in the attractive interactions occurring between colloids and collector surfaces. This effect was sensitive to ionic strength and was found to be more pronounced at lower ionic strength conditions. For the most electrostatically unfavorable scenario (ZSM-5 coatings in 1 mM KNO(3)), the enhanced deposition may also be attributed to inherent surface charge heterogeneity of ZSM-5 coatings due to aluminum in the crystalline structure. The two exceptions are ZSM-5 coated mirror-polished stainless steel and the unpolished aluminum surfaces, which are rougher than the other two samples of the same metal type but result in the least deposition. The reasons for these observations are discussed, as well as the effect of surface charge and hydrophobicity on the adhesion. The relative importance of surface roughness versus contributions of electrostatic interactions and hydrophobicity to the colloid deposition is also discussed.


Assuntos
Alumínio/química , Coloides/química , Aço Inoxidável/química , Zeolitas/química , Propriedades de Superfície
17.
Langmuir ; 25(3): 1620-6, 2009 Feb 03.
Artigo em Inglês | MEDLINE | ID: mdl-19123799

RESUMO

In this study, the impact of zeolite thin film coatings on bacterial deposition and "biofouling" of surfaces has been investigated in an aqueous environment. The synthesis of two types of zeolite coatings, ZSM-5 coated on aluminum alloy and zeolite A coated on stainless steel, and the characterization of the coated and bare metal surfaces are described. The extent of cell deposition onto the bare and zeolite-coated aluminum alloy and stainless steel surfaces is investigated in a parallel plate flow chamber system under a laminar flow conditions. The initial rates of bacterial transfer to the various surfaces are compared by utilizing a marine bacterium, Halomonas pacifica g, under a range of ionic strength conditions. H. pacifica g deposited onto bare metal surfaces to a greater extent as compared with cells deposited onto the zeolite coatings. The surface properties found to have the most notable effect on attachment are the electrokinetic and hydrophobicity properties of the metal and zeolite-coated surfaces. These results suggest that a combination of two chemical mechanisms-hydrophobic and electrostatic interactions-contribute to the antifouling nature of the zeolite surface. Additional observations on the relative role of the hydrodynamic and physical phenomena are also discussed.


Assuntos
Alumínio/química , Aderência Bacteriana , Halomonas/química , Aço Inoxidável/química , Zeolitas/química , Microscopia Eletrônica de Varredura , Propriedades de Superfície , Difração de Raios X
18.
J Am Chem Soc ; 128(3): 676-7, 2006 Jan 25.
Artigo em Inglês | MEDLINE | ID: mdl-16417330

RESUMO

A general method has been developed to immobilize antibodies onto an array surface by employing fusion proteins consisting of an elastin domain with tunable hydrophobic properties and an antibody-binding domain with high binding affinity and specificity for antibodies. Antibodies conjugated with the elastin fusion proteins can be directly printed on a self-assembled monolayer-modified glass slide in a functionally active orientation with a spatially defined pattern. An antibody array sensor for detection of tumor markers was fabricated to demonstrate the utility of the method. We expect that the method presented here could be a simple and universal platform to immobilize antibodies for the fabrication of a variety of antibody array sensors.


Assuntos
Anticorpos/química , Elastina/química , Análise Serial de Proteínas/métodos , Animais , Proteínas de Bactérias/química , Proteínas de Ligação a DNA/química , Interações Hidrofóbicas e Hidrofílicas , Proteínas do Tecido Nervoso/química , Proteínas Recombinantes de Fusão/química , Proteína Estafilocócica A/química
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