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1.
Small ; : e2102256, 2021 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-34528381

RESUMO

Despite exhibiting high specific capacities, Si-based anode materials suffer from poor cycle life as their volume change leads to the collapse of conductive network within the electrode. For this reason, the challenge lies in retaining the conductive network during electrochemical processes. Herein, to address this prominent issue, a cross-linked conductive binder (CCB) is designed for commercially available silicon oxides (SiOx ) anode to construct a resilient hierarchical conductive network from two aspects: on the one hand, exhibiting high electronic conductivity, CCB serves as an adaptive secondary conductive network in addition to the stiff primary conductive network (e.g., conductive carbon), facilitating faster interfacial charge transfer processes for SiOx in molecular level; on the other hand, the cross-linked structure of CCB shows resilient mechanical properties, which maintains the integrity of the primary conductive network by preventing electrode deformation during prolonged cycling. With the aid of CCB, untreated micro-sized SiOx anode material delivers an areal capacity of 2.1 mAh cm-2 after 250 cycles at 0.8 A g-1 . The binder design strategy, as well as, the relevant concepts proposed herein, provide a new perspective toward promoting the cycling stability of high-capacity Si-based anodes.

2.
Mater Sci Eng C Mater Biol Appl ; 128: 112354, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-34474902

RESUMO

In this paper, silk fibroin (SF) porous microcarriers containing strontium were constructed as injectable bone tissue engineering vehicles. The effects of SF concentration and strontium content on micromorphology, element distribution, strontium ion release and cellular behavior of the constructed microcarriers were investigated. The microcarriers with an open interconnected pore can be fabricated by controlling the concentration of SF. The strontium functionalized SF microcarriers showed the sustained release of strontium ion and allowed bone mesenchymal stem cells (BMSCs) to attach, proliferate and secrete extracellular matrix. Furthermore, the strontium functionalized SF microcarriers improved the osteogenic capability of BMSCs in vitro compared with those microcarriers without sustained release of strontium ion. This study presents a valuable approach to fabricate polymeric microcarriers with the capability of sustained release of strontium ion that show potential in bone tissue engineering applications.


Assuntos
Fibroínas , Diferenciação Celular , Osteogênese , Porosidade , Estrôncio , Engenharia Tecidual , Tecidos Suporte
3.
Nanomicro Lett ; 13(1): 173, 2021 Aug 13.
Artigo em Inglês | MEDLINE | ID: mdl-34387758

RESUMO

Recent years have witnessed a booming interest in grid-scale electrochemical energy storage, where much attention has been paid to the aqueous zinc ion batteries (AZIBs). Among various cathode materials for AZIBs, manganese oxides have risen to prominence due to their high energy density and low cost. However, sluggish reaction kinetics and poor cycling stability dictate against their practical application. Herein, we demonstrate the combined use of defect engineering and interfacial optimization that can simultaneously promote rate capability and cycling stability of MnO2 cathodes. ß-MnO2 with abundant oxygen vacancies (VO) and graphene oxide (GO) wrapping is synthesized, in which VO in the bulk accelerate the charge/discharge kinetics while GO on the surfaces inhibits the Mn dissolution. This electrode shows a sustained reversible capacity of ~ 129.6 mAh g-1 even after 2000 cycles at a current rate of 4C, outperforming the state-of-the-art MnO2-based cathodes. The superior performance can be rationalized by the direct interaction between surface VO and the GO coating layer, as well as the regulation of structural evolution of ß-MnO2 during cycling. The combinatorial design scheme in this work offers a practical pathway for obtaining high-rate and long-life cathodes for AZIBs.

4.
Mar Pollut Bull ; 165: 112144, 2021 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-33611230

RESUMO

From the mid-June to mid-July 2020, there was a massive bloom of Creseise acicula nearby the waters of Daya Bay Nuclear Power Plant Base (DNPP base). In order to find out the spatiotemporal dynamic characteristics of C. acicula and the main factors related to its outbreak and extinction, acoustic surveys and in-situ observations were performed. The results showed that the average abundance of C. acicula at the in-situ observation site fluctuated with the tidal rhythm. Furthermore, a horizontal migration pattern during ebb tide and a vertical subsidence trend of C. acicula was found. The outbreak of C. acicula bloom nearby the waters of DNPP base was the result of the joint action of water temperature, salinity and food availability etc. The extinction of C. acicula was mainly related to the adhesion of Licmophora, predation pressure from phytoplanktivorous fishes (such as Sardinella lemuru and Dussumieria elopsoides) and human intervention.


Assuntos
Baías , Centrais Nucleares , Acústica , China , Surtos de Doenças , Monitoramento Ambiental , Humanos
5.
J Biomater Sci Polym Ed ; 28(4): 337-349, 2017 03.
Artigo em Inglês | MEDLINE | ID: mdl-27931160

RESUMO

A main challenge for anticancer drugs is that the drugs can not arrive the cancer tissue at right time. In this work, a magnetic targeting nanoparticle based on hollow Fe3O4/graphene oxide (Fe3O4/GO) was developed as a potential tumor targeting drug carriers. The morphology results showed the Fe3O4 nanoparticles were uniformly wrapped by graphene oxide. After coating with graphene oxide, the Fe3O4/GO showed a higher saturation magnetization of 71.47 emu g-1 as compared to neat Fe3O4 nanoparticles. The drug loading and releasing experiment indicated the obtained Fe3O4/GO has a good loading capacity of of 0.41 mg mg-1 for 5-fluorouracil (5-FU) and a positive sensitive of acidic atmosphere. The CCK-8 assays of CMEC viability demonstrated the hollow Fe3O4/GO nanocarriers do not statistically exhibit toxicity with the concentration increasing from 2.5 to 40 µg mL-1 in vitro. These results suggested the prepared Fe3O4/GO has a potential application in anticancer drugs nanocarriers.


Assuntos
Portadores de Fármacos/química , Grafite/química , Nanopartículas de Magnetita/química , Óxidos/química , Antineoplásicos/química , Linhagem Celular , Sobrevivência Celular/efeitos dos fármacos , Portadores de Fármacos/toxicidade , Liberação Controlada de Fármacos , Fluoruracila/química
6.
J Mater Chem B ; 4(5): 947-961, 2016 Feb 07.
Artigo em Inglês | MEDLINE | ID: mdl-32263168

RESUMO

Injectable, in situ forming hydrogels have exhibited many advantages in regenerative medicine. Herein, we present the novel design of poly(l-glutamic acid) injectable hydrogels via the self-crosslinking of adipic dihydrazide (ADH)-modified poly(l-glutamic acid) (PLGA-ADH) and aldehyde-modified poly(l-glutamic acid) (PLGA-CHO), and investigate their potential in cartilage tissue engineering. Both the hydrazide modification degree of PLGA-ADH and oxidation degree of PLGA-CHO can be adjusted by the amount of activators and sodium periodate, respectively. Experiments reveal that the solid content of the hydrogels, -NH2/-CHO molar ratio, and oxidation degree of PLGA-CHO have a great effect on the gelation time, equilibrium swelling, mechanical properties, microscopic morphology, and in vitro degradation of the hydrogels. Encapsulation of rabbit chondrocytes within the hydrogels showed viability of the entrapped cells and cytocompatibility of the injectable hydrogels. A preliminary study exhibits injectability and rapid in vivo gel formation, as well as mechanical stability, cell ingrowth, and ectopic cartilage formation. These results suggest that the PLGA hydrogel has potential as an injectable cell delivery carrier for cartilage regeneration and could serve as a new biomaterial for tissue engineering.

7.
PLoS One ; 10(8): e0135611, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-26274326

RESUMO

Porous microcarriers were fabricated from synthesized poly(γ-benzyl-L-glutamate) (PBLG) polymer to engineer adipose tissue with lobule-like structure via the injectable approach. The adipogenic differentiation of human adipose-derived stem cells (hASCs) seeded on porous PBLG microcarriers was determined by adipogenic gene expression and glycerol-3-phosphate dehydrogenase enzyme activity. In vitro adipogenic cultivation was performed for 7 days, and induced hASC/PBLG complex (Adi-ASC/PBLG group) was subcutaneously injected into nude mice. Injections of PBLG microcarriers alone (PBLG group) and non-induced hASC/PBLG complex (ASC/PBLG group) served as controls. Newly formed tissues were harvested after 4 and 8 weeks. Generation of subcutaneous adipose tissue with typical lobule-like structure separated by fibrous septa was observed upon injection of adipogenic-induced hASC/microsphere complex. Adipogenesis significantly increased in the Adi-ASC/PBLG group compared with the control groups. The angiogenesis in the engineered adipose tissue was comparable to that in normal tissue as determined by capillary density and luminal diameter. Cell tracking assay demonstrated that labeled hASCs remained detectable in the neo-generated tissues 8 weeks post-injection using green fluorescence protein-labeled hASCs. These results indicate that adipose tissue with typical lobule-like structure could be engineered using injectable porous PBLG microspheres loaded with adipogenic-induced hASCs.


Assuntos
Tecido Adiposo/citologia , Tecido Adiposo/fisiologia , Ácido Poliglutâmico/análogos & derivados , Células-Tronco/citologia , Engenharia Tecidual/métodos , Adipogenia/genética , Adipogenia/fisiologia , Tecido Adiposo/ultraestrutura , Adulto , Animais , Diferenciação Celular , Movimento Celular , Células Cultivadas , Feminino , Glicerolfosfato Desidrogenase/metabolismo , Humanos , Camundongos Nus , Microesferas , Ácido Poliglutâmico/química , Gordura Subcutânea/citologia , Gordura Subcutânea/fisiologia
8.
J Mater Chem B ; 3(6): 1020-1031, 2015 Feb 14.
Artigo em Inglês | MEDLINE | ID: mdl-32261981

RESUMO

In search of an injectable cellular delivery vehicle for tissue regeneration, porous microspheres fabricated from the synthetic polypeptide of poly(γ-benzyl-l-glutamate) (PBLG) were developed. The structural and morphological characteristics of the microspheres could be adjusted by changing the amounts of the gelatin porogen. PBLG microspheres fabricated from 6.5% gelatin content exhibited an average pore diameter of 50.9 ± 10.3 µm and a porosity of 86.58 ± 2.37%. Degradation in vitro of the microspheres could be well controlled by adjusting the molecular weight of PBLG, and the degradability in vivo showed a satisfactory degradation time range from 8 to 12 weeks. Articular chondrocytes, which were seeded within the PBLG porous microspheres, exhibited progressive proliferation and deposition of the cartilaginous extracellular matrix. After cultivation for 2 days in vitro, the PBLG porous microspheres loaded with chondrocytes were injected subcutaneously into nude mice. At 4, 8 and 12 weeks post-injection, neo-generated tissue was harvested for histological observations, which showed a typical cartilage structure and cartilaginous matrix accumulation. A gradual increase of GAG and COL II content in neo-generated tissue was detected by biochemical analysis. These results indicate that the fabricated porous microspheres showing controllable degradation properties, good biocompatibility and cytocompatibility are potentially useful as an injectable vehicle for cartilage tissue engineering.

9.
Acta Biomater ; 10(1): 276-88, 2014 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-24025620

RESUMO

In this study a novel kind of porous poly(l-glutamic acid) (PLGA)/chitosan polyelectrolyte complex (PEC) microsphere was developed through electrostatic interaction between PLGA and chitosan. By adjusting the formula parameters chitosan microspheres with an average pore size of 47.5 ± 5.4 µm were first developed at a concentration of 2 wt.% and freeze temperature of -20 °C. For self-assembly of the PEC microspheres porous chitosan microspheres were then incubated in PLGA solution at 37 °C. Due to electrostatic interaction a large amount of PLGA (110.3 µg mg(-1)) was homogeneously absorbed within the chitosan microspheres. The developed PEC microspheres retained their original size, pore diameters and interconnected porous structure. Fourier transform infrared spectroscopy, thermal gravimetric analysis and zeta potential analysis revealed that the PEC microspheres were successfully prepared through electrostatic interaction. Compared with microspheres fabricated from chitosan, the porous PEC microspheres were shown to efficiently promote chondrocyte attachment and proliferation. After injection subcutaneously for 8 weeks PEC microspheres loaded with chondrocytes were found to produce significant more cartilaginous matrix than chitosan microspheres. These results indicate that these novel fabricated porous PLGA/chitosan PEC microspheres could be used as injectable cell carriers for cartilage tissue engineering.


Assuntos
Cartilagem/fisiologia , Quitosana/farmacologia , Eletrólitos/farmacologia , Microesferas , Ácido Poliglutâmico/farmacologia , Regeneração/efeitos dos fármacos , Tecidos Suporte/química , Animais , Cartilagem/efeitos dos fármacos , Fluorescência , Ácido Láctico/química , Camundongos , Microscopia Eletrônica de Varredura , Ácido Poliglicólico/química , Copolímero de Ácido Poliláctico e Ácido Poliglicólico , Porosidade , Eletricidade Estática
10.
J Microbiol Biotechnol ; 21(5): 494-502, 2011 May.
Artigo em Inglês | MEDLINE | ID: mdl-21617346

RESUMO

Coenzyme Q10 (CoQ10) is a widely used supplement in heart diseases treatment or antioxidative dietary. The microbial production of CoQ10 was enhanced by addition of solanesol and novel precursors recovered from waste tobacco. The novel precursors were separated by silica gel and identified as alpha-linolenic acid (LNA) and butylated hydroxytoluene (BHT) based on the effect on CoQ10 production and GC-MS. The effects of novel precursors on CoQ10 production by Sphingomonas sp. ZUTE03 were further evaluated in a two-phase conversion system. The precursor's combination of solanesol (70 mg/l) with BHT (30 mg/l) showed the best effect on the improvement of CoQ10 yield. A maximal CoQ10 productivity (9.5 mg l-1 h-1) was achieved after 8 h conversion, with a molar conversion rate of 92.6% and 92.4% on BHT and solanesol, respectively. The novel precursors, BHT and LNA in crude extracts from waste tobacco leaves, might become potential candidates for application in the industrial production of CoQ10 by microbes.


Assuntos
Extratos Vegetais/metabolismo , Sphingomonas/metabolismo , Tabaco/química , Ubiquinona/análogos & derivados , Hidroxitolueno Butilado/análise , Hidroxitolueno Butilado/isolamento & purificação , Hidroxitolueno Butilado/metabolismo , Microbiologia Industrial , Extratos Vegetais/análise , Extratos Vegetais/isolamento & purificação , Eliminação de Resíduos , Terpenos/análise , Terpenos/isolamento & purificação , Terpenos/metabolismo , Ubiquinona/metabolismo , Ácido alfa-Linoleico/análise , Ácido alfa-Linoleico/isolamento & purificação , Ácido alfa-Linoleico/metabolismo
11.
Molecules ; 15(6): 4055-66, 2010 Jun 04.
Artigo em Inglês | MEDLINE | ID: mdl-20657426

RESUMO

With the help of chemometric resolution methods, a technique for qualitative and quantitative determination of the volatile chemical constituents in radix Flemingiae Philippinensis by chromatography-mass spectrometry was developed. After the overlapping chromatographic peaks were resolved into pure chromatograms and spectra using a heuristic evolving latent projections (HELP) method, qualitative analysis was performed by similarity search of the obtained pure mass spectrum of each component in the NIST library and the quantitative results were obtained by calculating the total two-way response volume. A total of 63 components were separated and 55 components were identified, accounting for 90.62% of the total content. The main components were farnesol isomer and beta-caryophyllene, accounting for 31.33% and 12.60% of the total content, respectively. The obtained results can provide useful information for further study and development of radix Flemingiae Philippinensis.


Assuntos
Fabaceae/química , Cromatografia Gasosa-Espectrometria de Massas/métodos , Compostos Orgânicos Voláteis/química
12.
J Ind Microbiol Biotechnol ; 36(5): 687-93, 2009 May.
Artigo em Inglês | MEDLINE | ID: mdl-19221819

RESUMO

The use of coenzyme Q(10) (CoQ(10)) as a complementary therapy in heart failure will increase in proportion to the growth of the ageing population and the expansion of statins consumption. Economical production of CoQ(10) by microbes will become more important due to the growing demands of the pharmaceutical industry. Process simplification and integration might be one desirable pathway for economic production of CoQ(10) by microbial fermentation. In this report, the effect of a coupled fermentation-extraction process on CoQ(10) production by newly isolated Sphingomonas sp. ZUTEO3 was evaluated. It was found that the CoQ(10) yield of the coupled process was significantly higher than that of the traditional process. As optimal conditions in our experiment, 2% soybean oil was added to the original culture to enhance cell membrane permeability, and 50 mL hexane was added to the 30 h culture as an extracting solvent for the subsequent coupled fermentation-extraction process. The maximal yield of CoQ(10) reached 43.2 mg/L and 32.5 mg/g dry cell weight after 38 h of total fermentation period. The coupled process represents one potential pathway for CoQ(10) production with even higher yield and lower cost. This is the first report of CoQ(10) production by Sphingomonas sp. using a coupled fermentation-extraction process.


Assuntos
Fermentação , Microbiologia Industrial/métodos , Microbiologia do Solo , Sphingomonas/isolamento & purificação , Sphingomonas/metabolismo , Ubiquinona/análogos & derivados , Reatores Biológicos/microbiologia , Permeabilidade da Membrana Celular , Meios de Cultura/química , Meios de Cultura/metabolismo , Sphingomonas/química , Ubiquinona/biossíntese , Ubiquinona/química
13.
Wei Sheng Wu Xue Bao ; 48(2): 157-63, 2008 Feb.
Artigo em Chinês | MEDLINE | ID: mdl-18437995

RESUMO

A bacterium capable of producing Coenzyme Q10 (CoQ10, was isolated from soil. Based on analysis of the 16S rDNA sequence, traditional physiological characteristics, and Biolog-GN, the strain was belonging to the genus Sphingomonas and named as Sphingomonas sp. ZUTEO3. The optimum fermentation condition of CoQ10 production was as following: glucose 15 g/L, (NH4)2SO4 10 g/L, original pH 8.0 and at 25 degrees C. The addition of solanesol could improve CoQ10 production. The optimal condition for the bioconservation from solanesol to CoQ10 was as following: adding 0.75 g/L of raw solanesol after the first 12 h fermentation and continued for another 12 h fermentation. The maximal yield of CoQ10 reached 96.88 mg/L.


Assuntos
Fermentação , Microbiologia do Solo , Sphingomonas/isolamento & purificação , Sphingomonas/metabolismo , Terpenos/metabolismo , Ubiquinona/análogos & derivados , Biomassa , Meios de Cultura/metabolismo , Técnicas de Cultura , DNA Bacteriano/genética , DNA Ribossômico/genética , Dados de Sequência Molecular , Filogenia , RNA Ribossômico 16S , Sphingomonas/classificação , Sphingomonas/genética , Ubiquinona/metabolismo
14.
Protein Expr Purif ; 35(1): 17-24, 2004 May.
Artigo em Inglês | MEDLINE | ID: mdl-15039061

RESUMO

10-Deacetylbaccatin III-10-O-acetyltransferase (10-DABT) catalyzes the formation of baccatin III, which is an immediate diterpenoid precursor of Taxol. A cDNA encoding 10-DABT was cloned from Taxus baccata by using RT-PCR and screening a cDNA library. A study of its heterologous overexpression in Escherichia coli was carried out. To get high-level expression of recombinant enzyme, three kinds of IPTG inducible fusion expression systems (with glutathione S-transferase (GST), hexahistidine (6x His), and biotinylated tag) were used, and results of expression were compared. Fusion 10-DABT with different tags was expressed with diverse expression levels and solubility in the three systems. Optimum IPTG concentration, temperature, and inducing time for producing recombinant enzymes were found. Under higher IPTG concentration (up to 1 mM), the highest level of expression for fusion protein was obtained in the 6x His fusion system with phage T5 promoter, but expressed products were only partially soluble. With lower IPTG concentration (less than 0.5 mM), the highest expression was detected in the GST fusion system with tac promoter, and the lowest level of expression appeared in the biotinylated fusion system. The expression level in the latter system did not differ dramatically with a range of different inducer concentrations. GST and 6x His fusion proteins were mainly soluble in aqueous solutions and Triton X-100 improved the solubility of biotinylated fusion proteins (inferring this protein is membrane-associated). Fusion proteins could only be partially purified by a single affinity chromatography step for all three systems. Glutathione-coupled matrix and streptavidin-conjugated resin have higher specificity than Ni-NTA resin, and elution conditions were shown to affect enzyme activity. Three kinds of recombinant 10-DABT with different tags showed enzyme activity, but total enzyme activity was lost as a result of the affinity chromatography step. Thrombin and Factor Xa could be used for site-specific cleavage of fusion proteins, but the incubation temperature affected enzyme activity of recombinant enzymes.


Assuntos
Acetiltransferases/metabolismo , DNA Complementar/metabolismo , Escherichia coli/metabolismo , Proteínas Recombinantes de Fusão/metabolismo , Taxoides/metabolismo , Acetiltransferases/genética , Acetiltransferases/isolamento & purificação , Sequência de Bases , Linhagem Celular , Cromatografia de Afinidade/métodos , Clonagem Molecular , Escherichia coli/genética , Vetores Genéticos/genética , Vetores Genéticos/metabolismo , Dados de Sequência Molecular , Regiões Promotoras Genéticas , Proteínas Recombinantes de Fusão/genética , Temperatura
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