Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 11 de 11
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
1.
Amino Acids ; 2020 Nov 27.
Artigo em Inglês | MEDLINE | ID: mdl-33245424

RESUMO

As a promising cell therapy, neural crest-derived ectoderm mesenchymal stem cells (EMSCs) secrete high amounts of extracellular matrix (ECM) and neurotrophic factors, promoting neural stem cell (NSC) differentiation into neuronal lineages and aiding tissue regeneration. Additionally, the forced overexpression of secreted proteins can increase the therapeutic efficacy of the secretome. Tissue transglutaminase (TG2) is a ubiquitously expressed member of the transglutaminase family of calcium-dependent crosslinking enzymes, which can stabilize the ECM, inducing smart or living biomaterial to stimulate differentiation and enhance the neurogenesis of NSCs. In this study, we examined the neuronal differentiation of NSCs induced by TG2 gene-modified EMSCs (TG2-EMSCs) in a co-culture model directly. Two weeks after initiating differentiation, levels of the neuronal markers, tubulin beta 3 class III and growth-associated protein 43, were higher in NSCs in the TG2-EMSC co-culture group and those of the astrocytic marker glial fibrillary acidic protein were lower, compared with the control group. These results were confirmed by immunofluorescence, and laminin, fibronectin and sonic hedgehog (Shh) contributed to this effect. The results of western blot analysis and the enzyme-linked immunoassay showed that after TG2-EMSCs were co-cultured for 2 weeks, they expressed much higher levels of Shh than the control group. Moreover, the sustained release of Shh was observed in the TG2-EMSC co-culture group. Overall, our findings indicate that EMSCs can induce the differentiation of NSCs, of which TG2-EMSCs can promote the differentiation of NSCs compared with EMSCs.

2.
ACS Appl Mater Interfaces ; 11(8): 8453-8460, 2019 Feb 27.
Artigo em Inglês | MEDLINE | ID: mdl-30742412

RESUMO

Vertically oriented multilayered MoS2 nanosheets were successfully grown on p-GaN nanorod substrate using chemical vapor deposition (CVD) method. The p-GaN nanorod substrate was fabricated by dry etching employing self-assembled nickel (Ni) nanopartical as mask. Photoluminescence (PL) and Raman characterizations demonstrate the multilayered structure of MoS2 nanosheet growth on p-GaN nanorods as compared with the referential monolayer MoS2 on GaN wafer substrate under the same growth procedure. The growth model of vertical MoS2 nanosheet formed on GaN nanorods is evidently proposed according to the first-principle calculations. More importantly, it is demonstrated here that the as-grown vertical MoS2 nanosheets/p-GaN nanorod heterostructure holds promising applications in photodetector device, where high optical gain and broad spectral response in the visible range have been obtained.

3.
Food Chem ; 197(Pt A): 891-9, 2016 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-26617031

RESUMO

This study investigated the effects of dephosphorylation extent on infant in vitro gastric clotting property and gastrointestinal digestibility of milk protein concentrate. Dephosphorylation was affected by phosphatase type and incubation pH. A series of milk protein concentrate with 0-69% dephosphorylation were obtained by incubation with calf intestinal alkaline phosphatase at pH 6.5 for 0-420 min. Both ß- and αs1-caseins in the modified milk protein concentrate showed multiply dephosphorylated isoforms with different numbers of phosphate groups depending on the extent of dephosphorylation. With increased dephosphorylation of milk protein concentrate, the gastric clotting extent decreased and the gastrointestinal digestibility increased under infant in vitro conditions. These results suggested the potential of developing a dephosphorylated milk protein concentrate, with improved gastric clotting property and gastrointestinal digestibility, to simulate the multiply phosphorylated patterns of human casein and hence to further the humanization of infant formula on a molecular level.


Assuntos
Fosfatase Alcalina/química , Fórmulas Infantis/química , Proteínas do Leite/química , Modelos Biológicos , Fosfatos/análise , Proteólise , Animais , Fenômenos Bioquímicos , Caseínas/química , Bovinos , Suco Gástrico/química , Humanos , Lactente
4.
Food Chem ; 172: 836-43, 2015 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-25442628

RESUMO

This study investigated the effects of alkaline pretreatments and acid extraction conditions on the production of acid-soluble collagen (ASC) from grass carp skin. For alkaline pretreatment, 0.05 and 0.1M NaOH removed non-collagenous proteins without significant loss of ASC at 4, 10, 15 and 20 °C; while 0.2 and 0.5M NaOH caused significant loss of ASC, and 0.5M NaOH caused structural modification of ASC at 15 and 20 °C. For acid extraction at 4, 10, 15 and 20 °C, ASC was partly extracted by 0.1 and 0.2M acetic acid, while 0.5 and 1.0M acetic acid resulted in almost complete extraction. The processing conditions involving 0.05-0.1M NaOH for pretreatment, 0.5M acetic acid for extraction and 4-20 °C for both pretreatment and extraction, produced ASC with the structural integrity being well maintained and hence were recommended to prepare ASC from grass carp skin in practical application.


Assuntos
Colágeno/isolamento & purificação , Proteínas de Peixes/isolamento & purificação , Pele/química , Ácidos/química , Álcalis/química , Animais , Carpas , Colágeno/química , Proteínas de Peixes/química , Solubilidade
5.
J Mater Chem B ; 2(24): 3791-3798, 2014 Jun 28.
Artigo em Inglês | MEDLINE | ID: mdl-32261725

RESUMO

A type of photo- and thermo-responsive composite microsphere composed of reduced graphene oxide nanoparticles and poly(N-isopropylacrylamide) (rGO@pNIPAM) is successfully fabricated by a facile solution mixing method. Due to the high optical absorbance and thermal conduction of rGO, the composite microspheres are endowed with the new property of photo-response, in addition to the intrinsic thermally sensitive property of pNIPAM. This new ability undoubtedly enlarges the scope of applications of the microgel spheres. Furthermore, through controlling the rGO content in the composite, the photo- and thermo-sensitivity of the composite can be effectively modulated. That is, with a lower rGO content (≤32% by weight), the composite microspheres perform only thermally induced changes, such as volume contraction (by ∼45% in diameter) and drug release, when crossing the lower critical solution temperature of pNIPAM. With a higher rGO content (∼47.5%), both temperature and light irradiation can trigger changes in the composite. However, when the rGO content is increased to around 64.5%, the thermo-responsivity of the composite disappears, and the spheres exhibit only photo-induced drug release. With a further increase in rGO content, the environmentally responsive ability of the microspheres vanishes.

6.
J Phys Chem B ; 117(33): 9677-82, 2013 Aug 22.
Artigo em Inglês | MEDLINE | ID: mdl-23931727

RESUMO

Environmentally responsive materials are attractive for advance biomedicine applications such as controlled drug delivery and gene therapies. Recently, we have introduced the fabrication of a novel type of stimuli-sensitive lipogel composite consisting of poly(N-isopropylacrylamide) (pNIPAM) microgel particles and lipids. In this study, we demonstrated the temperature-triggered drug release behavior and the tunable drug loading and release capacities of the lipogel. At room temperature (22 °C), no calcein was released from the lipogel over time. At body temperature (37 °C), the release process was significantly promoted; lipids in the lipogel acted as drug holders on the pNIPAM scaffold carrier and prolonged the calcein release process from 10 min to 2 h. Furthermore, the loading and release of calcein could be effectively controlled by modulating the relative amount of lipids incorporated in the lipogel, which can be realized by the salt-induced lipid release of the lipogel.


Assuntos
Resinas Acrílicas/química , Portadores de Fármacos/química , Lipídeos/química , Fluoresceínas/química , Géis/química , Cinética , Temperatura
7.
Phys Chem Chem Phys ; 15(29): 12227-34, 2013 Aug 07.
Artigo em Inglês | MEDLINE | ID: mdl-23770915

RESUMO

By considering the mechanism of preferential adsorption, we systemically investigated the charging behavior of spherical particles in nonpolar media by the regulation of charged inverse micelles. Using the nonlinear Poisson-Boltzmann equation, we simulated the effects of micelle concentrations, particle concentrations, and particle sizes on the surface potential of spheres at the thermodynamic equilibrium of the system. As a result, we found two different micelle concentration-dependent regions for the surface potential of spheres which can be explained in terms of the mechanism of preferential adsorption and the electrostatic properties of charged reverse micelles between the particle surface and the double layer. Additionally, similar results were observed in an experiment for studying zeta potential of colloidal particles dispersed in AOT (sodium di-2-ethylhexyl sulfosuccinate)-dodecane solution.

8.
Langmuir ; 29(25): 8039-45, 2013 Jun 25.
Artigo em Inglês | MEDLINE | ID: mdl-23738716

RESUMO

Cellular uptake of materials plays a key role in their biomedical applications. In this work, based on the cell-mimic giant unilamellar vesicles (GUVs) and a novel type of microscale materials consisting of stimuli-responsive poly(N-isopropylacrylamide) microgel particles and the incorporated lipids, the influence of particle surface chemistry, including hydrophobic/hydrophilic property and lipid decorations, on the adsorption and consequent internalization of particles into GUVs was investigated. It is found that the decoration of particle surface with lipids facilitates the adsorption of particles on GUV membrane. After that, the hydrophobic property of particle surface further triggers the internalization of particles into GUVs. These results demonstrate the importance of surface properties of particles on their interactions with lipid membranes and are helpful to the understanding of cellular uptake mechanism.


Assuntos
Lipossomas Unilamelares/química , Interações Hidrofóbicas e Hidrofílicas , Microscopia Confocal , Microscopia Eletroquímica de Varredura , Modelos Teóricos , Propriedades de Superfície
9.
Biochim Biophys Acta ; 1828(8): 1918-25, 2013 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-23608122

RESUMO

Quartz crystal microbalance with dissipation (QCM-D) technique is one of the most effective methods to monitor the dynamic behaviors of a layer on a solid surface. Moreover, it has been reported recently that it is able to provide a fingerprint for the peptide-membrane interactions. In this work, QCM-D technique combined with computer simulations was employed to investigate the deposition and transformation of vesicles, as well as the subsequent membrane-melittin interactions on different substrates. A range of substrate surfaces, i.e. naked SiO2 without or with Au/polyelectrolyte coating, were produced. The nature of the substrate determined whether the adsorbed vesicles were present as a high-quality supported bilayer or an assembled vesicle matrix, which consequently influenced the membrane-melittin interactions. It was indicated by the related computer simulations that the lipid packing state of the membrane was a key factor to determine the mechanism of membrane-peptide interactions. Furthermore, this work might be a good example of the application of QCM-D for the exploration of membrane-active peptides.


Assuntos
Membrana Celular/química , Bicamadas Lipídicas/química , Meliteno/química , Técnicas de Microbalança de Cristal de Quartzo , Dióxido de Silício/metabolismo , Lipossomas Unilamelares/química , Membrana Celular/metabolismo , Simulação por Computador , Bicamadas Lipídicas/metabolismo , Meliteno/metabolismo , Modelos Moleculares , Especificidade por Substrato , Propriedades de Superfície
10.
J Phys Chem B ; 116(31): 9432-8, 2012 Aug 09.
Artigo em Inglês | MEDLINE | ID: mdl-22794087

RESUMO

The molecular-level interactions of an antimicrobial peptide melittin with supported membrane were studied by the combination of dissipative quartz crystal microbalance (QCM-D) experiments and computer simulations. We found the response behavior of lipids upon peptide adsorption greatly influence their interactions. The perturbance and reorientation of the lipid in liquid phase facilitate the insertion of melittin in a trans-membrane way, but in solid phase, asymmetrical membrane disruption happens. Apart from the lipid state, the local peptide-to-lipid ratio also affects the insertion capacity of melittin. When the local peptide number density is high, adjacent peptides can cooperatively penetrate into the membrane. This observation explains the occurrence of the conventional "carpet" mechanism.


Assuntos
Bicamadas Lipídicas/química , Meliteno/química , Técnicas de Microbalança de Cristal de Quartzo , Adsorção , Simulação por Computador , Modelos Moleculares , Temperatura
11.
Nanotechnology ; 22(31): 315303, 2011 Aug 05.
Artigo em Inglês | MEDLINE | ID: mdl-21747161

RESUMO

A novel kind of biomolecule-based electrical bistable device composed of phospholipid-CdTe nanoparticle multilayered films was demonstrated. The composite film was fabricated by a facile solution-cast method. X-ray reflectivity and transmission electron microscopy measurements showed the homogeneous distribution of nanoparticles within the lamellar lipid matrix with long-range ordering. Current-voltage scans on the Al/(lipid-nanoparticle composite film)/ITO/glass structures at room temperature exhibited an obvious current bistable phenomenon. Further investigation of such bionanoparticle composite film promises to show its importance for applications in future memory nanodevices with tailored performance.


Assuntos
Compostos de Cádmio/química , Nanocompostos/química , Nanopartículas/química , Fosfolipídeos/química , Telúrio/química , Eletricidade , Nanocompostos/ultraestrutura , Nanopartículas/ultraestrutura
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA